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Background: Staphylococcus aureus bloodstream infection (bacteremia) is traditionally treated with at least 2 weeks of intravenous (IV) antibiotics in adults, 3-7 days in children, and often longer for those with complicated disease. The current practice of treating S. aureus bacteremia (SAB) with prolonged IV antibiotics (rather than oral antibiotics) is based on historical observational research and expert opinion. Prolonged IV antibiotic therapy has significant disadvantages for patients and healthcare systems, and there is growing interest in whether a switch to oral antibiotics following an initial period of IV therapy is a safe alternative for clinically stable patients., Protocol: The early oral switch (EOS) domain of the S. aureus Network Adaptive Platform (SNAP) trial will assess early switch to oral antibiotics compared with continued IV treatment in clinically stable patients with SAB. The primary endpoint is 90-day all-cause mortality. Hospitalised SAB patients are assessed at platform day 7 ±2 (uncomplicated SAB) and day 14 ±2 (complicated SAB) to determine their eligibility for randomization to EOS (intervention) or continued IV treatment (current standard of care)., Discussion: Recruitment is occurring in the EOS domain of the SNAP trial. As of August 2023, 21% of all SNAP participants had been randomized to the EOS domain, a total of 264 participants across 77 centers, with an aim to recruit at least 1000 participants. We describe challenges and facilitators to enrolment in this domain to aid those planning similar trials., Competing Interests: Potential conflicts of interest. A. McGlothlin is an employee of Berry Consultants, LLC, a statistical consulting firm that specializes in the design of adaptive and platform clinical trials. Berry Consultants received compensation for work included in the content of the submission. A. C. Bowen reports participation as a member of the CAMERA-2 data and safety monitoring board (DSMB) and as chair of the Skin Trial DSMB; she also reports participation on Phage Trial DSMB and participation as Chair of FOSUTI DSMB; a role as Vice President of the World Society of Paediatric Infectious Diseases and as Co-Chair, Australian and New Zealand Pediatric Infectious Diseases group of the Australasian Society of Infectious Diseases (ASID). D. L. Paterson reports grants or contracts made to institution and unrelated to this work from Shionogi, Merck, and Pfizer; consulting fees to author from Antimicrobial Resistance Action Fund and Spero Therapeutics; payment or honoraria for lectures, presentations, speaker's bureaus, manuscript writing, or educational events to author from Pfizer and Merck; support for attending meetings and/or travel to author from Pfizer; and an unpaid leadership or fiduciary role with ASID. J. A. Roberts reports contracts or grants paid to institution and unrelated to this work from Pfizer and QPEX and investigator grant (APP2009736) and Advancing Queensland Clinical Fellowship; consulting fees paid to author from QPEX, Advanz Pharma, Gilead, Pfizer, Sandoz, Summit Pharma, and MSD; payment to author for lectures, presentations, speaker's bureaus, manuscript writing, or educational events from MSD, Gilead, Pfizer, and Cipla. J. Ten Oever reports grants or contracts unrelated to this work from Pfizer and MSD; support for attending meetings and/or travel to author from Pfizer; M. P. Cheng reports research support from the Canadian Institutes of Health Research and is supported by the Fonds de Recherche du Québec—Santé; research contracts from Cidara Therapeutics, Scynexis, and Amplyx Pharmaceuticals; consulting fees as a scientific consultant for AstraZeneca, Takeda, Merck, and Pfizer; 3 pending patents (Methods for detecting tissue damage, graft-versus-host disease, and infections using cell-free DNA profiling; Methods for assessing the severity and progression of SARS-CoV-2 infections using cell-free DNA; and rapid identification of antimicrobial resistance and other microbial phenotypes using highly multiplexed fluorescence in situ hybridization); stock options as a member of the scientific advisory board for GEn1E Lifesciences and Nomic Bio; and equity as co-founder of Kanvas Biosciences. R. J. Lewis is an employee of Berry Consultants, LLC, a statistical consulting firm that specializes in the design of adaptive and platform clinical trials. Berry Consultants received compensation for work included in the content of the submission. S. A. W. reports personal consulting fees from ClinicIQ pharma and Roche; an unpaid role as chair of Australian Clinical Trials Alliance; and stock and options with ClinicIQ. S. C. Morpeth reports grants or contracts unrelated to this work from the HRC, and a nonremunerated role as the Chair of the New Zealand Microbiology Network. S. Kalimuddin reports consulting fees from Gilead, Janssen, and Takeda (payments made to Singapore General Hospital) and grants or contracts unrelated to this work from National Medical Research Council, Singapore. S. Y. C. Tong reports a contract as a paid consultant for advice on clinical trial design, and consulting fees from Roivant Sciences as a paid consultant for advice on clinical trial design; and reports grants or contracts unrelated to this work from Australian National Health and Medical Research Council. T. C. Lee reports research salary support from Fonds de Recherche Quebec–Sante, operating funds for other studies including CATCO from the CIHR; and operating funds for other studies from the McGill Interdisciplinary Institute Infection and Immunity. Conflicts that the editors consider relevant to the content of the article have been disclosed. Collaborating authors have not been asked for their potential conflicts. A. Campbell reports National Health and Medical Research Council (grant 2014900) for SNAPPY and Perth Children's Hospital Foundation for site funding for SNAPPY and Raine Clinician Fellowship; participation on Data safety monitoring board for the B part of the NT Meningococcal B study; a role as Co-chair Australian and New Zealand Pediatric Infectious Diseases Special Interest Group Committee. A. Legg reports payment to author for Australian Pharmacy Council—EVUSHELD module and webinar and SHPA webinar; support for attending meetings and/or travel from Therapeutic Guidelines group meeting. L. Whiteway reports being remunerated for time attending meetings, and review of patient facing materials as consumer/PPI representative on the SNAP global trial steering committee. M. Bonten reports grants or contracts (all payments to UMCU) from Janssen Vaccines, Merck, LimmaTech, CureVac, Spherecydes; consulting fees (all payments to UMCU) from Janssen Vaccines, AstraZeneca, Pfizer, Sperecydes, Shionogi, GSK; participation on Data Safety Monitoring Board or Advisory Board for Sanofi (payments to UMCU). S. A. Webb reports grant from National Health and Medical Research Council of Australia that supports SNAP; personal consultings fees from ClinicIQ pharma and Roche; no patents or participation on Data Safety Monitoring Boards or Advisory Boards relevant to this work; unpaid roles as Chair and Director of Australian Clinical Trials Alliance; stock or stock options with Reliis. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America.)

Older adults hospitalized in internal medicine wards or long-term care facilities (LTCF) are progressively increasing. Older adults with multimorbidity are more susceptible to infections, as well as to more vulnerable to adverse effects (and interactions) of antibiotics, resulting in a need for effective and safer strategies for antimicrobial stewardship (ASM), both in hospitalization wards and long-term care facilities. Studies on antimicrobial stewardship in older patients are scarce and guidelines are required. Given the peculiarities of the optimization of antimicrobial prescription in individual older adults for common infections, tactics to overcome barriers need an update. The use of rapid diagnosis tests, biomarkers, de-escalation and switching from intravenous to oral/subcutaneous therapy strategies are examples of successful AMS interventions. AMS interventions are associated with reduced side effects, lower mortality, shorter hospital stays, and reduced costs. The proposed AMS framework in LTCF should focus on five domains: strategic vision, team, interventions, patient-centred care and awareness. Internists can partner with geriatrists, pharmacists and infectious disease specialists to address barriers and to improve patient care., Competing Interests: Declaration of competing interest Authors disclose no conflicts of interest regarding this manuscript., (Copyright © 2024. Published by Elsevier B.V.)

Introduction: Reports regarding the external validity of randomized controlled trials (RCTs) are scarce. We aimed to assess the population external validity of an investigator-initiated RCT on the duration of antibiotics for the treatment of Gram-negative bacteremia by comparing patients included in the RCT to patients that were not included in the trial., Methods: Hospitalized patients with Gram-negative bacteremia were recruited into an RCT and randomized to receive 7 or 14 days of covering antibiotic therapy in Israel and Italy from 2013 to 2017. In a concomitant observational study, RCT participants were compared with patients who fulfilled the inclusion criteria but were not included in the trial due to participation in other trials, discharge before approached by researchers, refusal to participate, or unwillingness of the treating physician to allow participants' recruitment., Results: Six hundred and four RCT patients were compared with 613 nonincluded patients. Almost 50% of nonincluded patients (288/613) were dependent on others for activities of daily living at baseline compared to 37.7% of RCT participants (228/604). Dementia was nearly 2-fold more frequent in nonincluded patients than those included (5.9% [36/613] versus 3.6% [22/604], p = 0.07). Patients who were not included in the RCT were more likely to acquire their infection in the hospital (53.3% [327/613] versus 29.1% [176/604], p < 0.001). The primary composite outcome of mortality, clinical failure, readmissions, or extended hospitalization at 90 days occurred in 353 of 613 nonincluded patients (57.6%) compared to 299 of 604 RCT participants (49.6%), p = 0.005. However, on multivariate analysis noninclusion in the RCT was not an independent risk factor for clinical failure and mortality., Conclusions: RCTs, even with broad eligibility criteria, do not represent the whole spectrum of patients and leave out a population with more severe illness for whom the evidence is lacking., (© 2022 S. Karger AG, Basel.)

Objectives: Mortality among patients with carbapenem-resistant Acinetobacter baumannii (CRAB) infections varies between studies. We examined whether in vivo fitness of CRAB strains is associated with clinical outcomes in patients with CRAB infections., Methods: Isolates were collected from patients enrolled in the AIDA trial with hospital-acquired pneumonia, bloodstream infections and/or urinary tract infections caused by CRAB. The primary outcome was 14-day clinical failure, defined as failure to meet all criteria: alive; haemodynamically stable; improved or stable Sequential Organ Failure Assessment (SOFA) score; improved or stable oxygenation; and microbiological cure of bacteraemia. The secondary outcome was 14-day mortality. We tested in vivo growth using a neutropenic murine thigh infection model. Fitness was defined based on the CFU count 24 hours after injection of an inoculum of 10 5  CFU. We used mixed-effects logistic regression to test the association between fitness and the two outcomes., Results: The sample included 266 patients; 215 (80.8%) experienced clinical failure. CRAB fitness ranged from 5.23 to 10.08 log CFU/g. The odds of clinical failure increased by 62% for every 1-log CFU/g increase in fitness (OR 1.62, 95% CI 1.04-2.52). After adjusting for age, Charlson score, SOFA score and acquisition in the intensive care unit, fitness remained significant (adjusted OR 1.63, 95% CI 1.03-2.59). CRAB fitness had a similar effect on 14-day mortailty, although the association was not statistically significant (OR 1.56, 95% CI 0.95-2.57). It became significant after adjusting for age, Charlson score, SOFA score and recent surgery (adjusted OR 1.88, 95% CI 1.09-3.25)., Conclusions: In vivo CRAB fitness was associated with clinical failure in patients with CRAB infection., (Copyright © 2021 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Background: Nocardiosis is a rare infection that is often difficult to treat and may be life-threatening. There is no consensus on its management., Objectives: Our aim was to provide the current evidence for the diagnosis and management of individuals with nocardiosis, and to propose a management approach for this uncommon infection., Sources: We systematically searched the medical literature on nocardiosis for studies published between 2010 and 2020 and describing ten or more individuals., Content: Nocardiosis, a primarily opportunistic infection which may occur in immunocompetent persons, most commonly involves the lungs and frequently disseminates to other sites including the central nervous system. The reference standard for Nocardia species identification is molecular biology, and the preferred method for antibiotic susceptibility testing (AST) is broth microdilution. Monotherapy seems appropriate for patients with primary skin nocardiosis or non-severe pulmonary disease; we reserve a multidrug regimen for more severe infections. Species identification and AST results are often missing at initiation of antibiotics. Trimethoprim-sulfamethoxazole is the preferred agent for initial therapy, because Nocardia is very often susceptible to this agent, and because it has been the keystone of nocardiosis treatment for years. Linezolid, to which Nocardia is almost always susceptible, may be an alternative. When combination therapy is required, the repertoire of companion drugs includes third-generation cephalosporins, amikacin and imipenem. Therapeutic modifications should take into account clinical response to initial therapy and AST results. Treatment duration of 6 months is appropriate for most situations, but longer durations are preferred for disseminated nocardiosis and shorter durations are reasonable in low-risk situations. Secondary prophylaxis may be considered in selected individuals with permanent immunosuppression., Implications: We hereby provide the clinician with an easy-to-use algorithm for the management of individuals with nocardiosis. We also illuminate gaps in evidence and suggest future research directions., (Copyright © 2021 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.)

Background: Population external validity is the extent to which an experimental study results can be generalized from a specific sample to a defined population. In order to apply the results of a study, we should be able to assess its population external validity. We performed an investigator-initiated randomized controlled trial (RCT) (AIDA study), which compared colistin-meropenem combination therapy to colistin monotherapy in the treatment of patients infected with carbapenem-resistant Gram-negative bacteria. In order to examine the study's population external validity and to substantiate the use of AIDA study results in clinical practice, we performed a concomitant observational trial., Methods: The study was conducted between October 1st, 2013 and January 31st, 2017 (during the RCTs recruitment period) in Greece, Israel and Italy. Patients included in the observational arm of the study have fulfilled clinical and microbiological inclusion criteria but were excluded from the RCT due to receipt of colistin for > 96 h, refusal to participate, or prior inclusion in the RCT. Non-randomized cases were compared to randomized patients. The primary outcome was clinical failure at 14 days of infection onset., Results: Analysis included 701 patients. Patients were infected mainly with Acinetobacter baumannii [78.2% (548/701)]. The most common reason for exclusion was refusal to participate [62% (183/295)]. Non-randomized and randomized patients were similar in most of the demographic and background parameters, though randomized patients showed minor differences towards a more severe infection. Combination therapy was less common in non-randomized patients [31.9% (53/166) vs. 51.2% (208/406), p = 0.000]. Randomized patients received longer treatment of colistin [13 days (IQR 10-16) vs. 8.5 days (IQR 0-15), p = 0.000]. Univariate analysis showed that non-randomized patients were more inclined to clinical failure on day 14 from infection onset [82% (242/295) vs. 75.5% (307/406), p = 0.042]. After adjusting for other variables, non-inclusion was not an independent risk factor for clinical failure at day 14., Conclusion: The similarity between the observational arm and RCT patients has strengthened our confidence in the population external validity of the AIDA trial. Adding an observational arm to intervention studies can help increase the population external validity and improve implementation of study results in clinical practice., Trial Registration: The trial was registered with ClinicalTrials.gov, number NCT01732250 on November 22, 2012.

Objective: Carbapenems are considered treatment of choice for bacteremia caused by potential AmpC-producing bacteria, including Enterobacter spp. We aimed to compare mortality following carbapenem vs. alternative antibiotics for the treatment of Enterobacter spp. bacteremia. Patients and Methods: We conducted a retrospective study in two centers in Israel. We included hospitalized patients with Enterobacter bacteremia treated with third-generation cephalosporins (3GC), piperacillin/tazobactam, quinolones, or carbapenem monotherapy as the main antibiotic in the first week of treatment, between 2010 and 2017. Cefepime was excluded due to nonavailability during study years. The primary outcome was 30-day all-cause mortality. Univariate and multivariate analyses were conducted, introducing the main antibiotic as an independent variable. Results: Two hundred seventy-seven consecutive patients were included in the analyses. Of these, 73 were treated with 3GC, 39 with piperacillin/tazobactam, 104 with quinolones, and 61 with carbapenems. All-cause 30-day mortality was 16% (45 patients). The type of antibiotics was not significantly associated with mortality on univariate or multivariate analyses. With carbapenems as reference, adjusted odds ratios (ORs) for mortality were 0.708, 95% confidence interval (CI) 0.231-2.176 with 3GC; OR 1.172, 95% CI 0.388-3.537 with piperacillin/tazobactam; and OR 0.586, 95% CI 0.229-1.4 with quinolones. The main antibiotic was not associated with repeated growth of Entrobacter spp. in blood cultures or other clinical specimens. Resistance development was observed with 3GC and piperacillin/tazobactam. Conclusions: Carbapenem treatment was not advantageous to alternative antibiotics, including 3GC, among patients with Enterobacter spp. bacteremia in an observational study.

Objectives: To maximise efficacy and minimise toxicity, special considerations are required for antibiotic prescription in elderly patients. This review aims to provide practical suggestions for the optimal management of antibiotic therapy in elderly patients., Methods: This was a narrative review. A literature search of published articles in the last 15 years on antibiotics and elderly patients was performed using the Cochrane Library and PubMed electronic databases. The three priority areas were identified: (i) pharmacokinetics/pharmacodynamics (PK/PD) for optimising dosage regimens and route of administration; (ii) antibiotic dosages in some special subpopulations; and (iii) treatment considerations relating to different antibiotic classes and their adverse events., Results: Clinicians should understand the altered PK/PD of drugs in this population owing to co-morbid conditions and normal physiological changes associated with ageing. The body of evidence justifies the need for individualised dose selection, especially in patients with impaired renal and liver function. Clinicians should be aware of the major drug-drug interactions commonly observed in the elderly as well as potential side effects., Conclusion: Antibiotic therapy in the elderly requires a comprehensive approach, including strategies to improve appropriate antibiotic prescribing, limit their use for uncomplicated infections and ensure the attainment of an optimal PK/PD target. To this purpose, further studies involving the elderly are needed to better understand the PK of antibiotics. Moreover, it is necessary to assess the role therapeutic drug monitoring in guiding antibiotic therapy in elderly patients in order to evaluate its impact on clinical outcome., (Copyright © 2020. Published by Elsevier Ltd.)

Importance: Methicillin-resistant Staphylococcus aureus (MRSA) bacteremia is associated with mortality of more than 20%. Combining standard therapy with a β-lactam antibiotic has been associated with reduced mortality, although adequately powered randomized clinical trials of this intervention have not been conducted., Objective: To determine whether combining an antistaphylococcal β-lactam with standard therapy is more effective than standard therapy alone in patients with MRSA bacteremia., Design, Setting, and Participants: Open-label, randomized clinical trial conducted at 27 hospital sites in 4 countries from August 2015 to July 2018 among 352 hospitalized adults with MRSA bacteremia. Follow-up was complete on October 23, 2018., Interventions: Participants were randomized to standard therapy (intravenous vancomycin or daptomycin) plus an antistaphylococcal β-lactam (intravenous flucloxacillin, cloxacillin, or cefazolin) (n = 174) or standard therapy alone (n = 178). Total duration of therapy was determined by treating clinicians and the β-lactam was administered for 7 days., Main Outcomes and Measures: The primary end point was a 90-day composite of mortality, persistent bacteremia at day 5, microbiological relapse, and microbiological treatment failure. Secondary outcomes included mortality at days 14, 42, and 90; persistent bacteremia at days 2 and 5; acute kidney injury (AKI); microbiological relapse; microbiological treatment failure; and duration of intravenous antibiotics., Results: The data and safety monitoring board recommended early termination of the study prior to enrollment of 440 patients because of safety. Among 352 patients randomized (mean age, 62.2 [SD, 17.7] years; 121 women [34.4%]), 345 (98%) completed the trial. The primary end point was met by 59 (35%) with combination therapy and 68 (39%) with standard therapy (absolute difference, -4.2%; 95% CI, -14.3% to 6.0%). Seven of 9 prespecified secondary end points showed no significant difference. For the combination therapy vs standard therapy groups, all-cause 90-day mortality occurred in 35 (21%) vs 28 (16%) (difference, 4.5%; 95% CI, -3.7% to 12.7%); persistent bacteremia at day 5 was observed in 19 of 166 (11%) vs 35 of 172 (20%) (difference, -8.9%; 95% CI, -16.6% to -1.2%); and, excluding patients receiving dialysis at baseline, AKI occurred in 34 of 145 (23%) vs 9 of 145 (6%) (difference, 17.2%; 95% CI, 9.3%-25.2%)., Conclusions and Relevance: Among patients with MRSA bacteremia, addition of an antistaphylococcal β-lactam to standard antibiotic therapy with vancomycin or daptomycin did not result in significant improvement in the primary composite end point of mortality, persistent bacteremia, relapse, or treatment failure. Early trial termination for safety concerns and the possibility that the study was underpowered to detect clinically important differences in favor of the intervention should be considered when interpreting the findings., Trial Registration: ClinicalTrials.gov Identifier: NCT02365493.

Objectives: Intranasal septal splints are often used in nasal septal surgeries. Routine use of postoperative antibiotics is an accepted practice, although data regarding its efficacy in preventing postsurgical complications are limited. This study aimed to examine bacterial colonization on septal splints following prophylactic antibiotic therapy and the association with postoperative infections., Methods: Fifty-five patients underwent septoplasty by a single surgeon between March 2015 and April 2016. All had intranasal septal splints and were given antibiotic prophylaxis for 7 days until removal of splints. Nasal cultures were taken before surgery, and septal splints were examined for bacterial colonization following their removal., Results: Thirty-six patients (65%) had positive nasal culture prior to surgery. The most common isolates were Staphylococcus aureus (30%) and Enterobacteriaceae species (66%). All these patients had postoperative bacterial colonization on septal splints. In 15 patients with negative preoperative cultures, bacteria were isolated postoperatively. An increased resistance profile was documented postoperatively in 9 patients (16%), including two with multidrug resistance. In two of these patients preoperative wild-type strains acquired antibiotic resistance postoperatively. No adverse drug reactions to antibiotics were reported., Conclusions: Increased bacterial growth and emergence of resistant strains were observed on intranasal septal splints despite prophylactic antibiotic treatment. Nonetheless, this did not translate into clinical infection. Thus, considering antibiotics overuse and increasing bacterial resistance, further research is needed to determine the role of antibiotic prophylaxis in the setting of intranasal splints.

Little evidence exists addressing the clinical value of adding gentamicin to ampicillin for invasive listeriosis. A multicenter retrospective observational study of nonpregnant adult patients with invasive listeriosis (primary bacteremia, central nervous system (CNS) disease, and others) in 11 hospitals in Israel between the years 2008 and 2014 was conducted. We evaluated the effect of penicillin-based monotherapy compared with early combination therapy with gentamicin, defined as treatment started within 48 h of culture results and continued for a minimum of 7 days. Patients who died within 48 h of the index culture were excluded. The primary outcome was 30-day all-cause mortality. A total of 190 patients with invasive listeriosis were included. Fifty-nine (30.6%) patients were treated with early combination therapy, 90 (46.6%) received monotherapy, and 44 (22.8%) received other treatments. Overall 30-day mortality was 20.5% (39/190). Factors associated with mortality included lower baseline functional status, congestive heart failure, and higher sequential organ failure assessment score. Source of infection, treatment type, and time from culture taken date to initiation of effective therapy were not associated with mortality. In multivariable analysis, monotherapy was not significantly associated with increased 30-day mortality compared with early combination therapy (OR 1.947, 95% CI 0.691-5.487). Results were similar in patients with CNS disease (OR 3.037, 95% CI 0.574-16.057) and primary bacteremia (OR 2.983, 95% CI 0.575-15.492). In our retrospective cohort, there was no statistically significant association between early combination therapy and 30-day mortality. A randomized controlled trial may be necessary to assess optimal treatment.

Background: little is known on the clinical implications of vancomycin trough levels among older patients., Objective: to evaluate the association between vancomycin levels and outcomes among older versus younger patients., Design: retrospective study., Subjects: patients aged 18-64 and ≥65 years treated with vancomycin for documented methicillin resistant Staphylococcus aureus (MRSA) infections., Methods: we compared the effectiveness and toxicity of vancomycin according to trough levels in older versus younger patients. Subgroup analysis of patients with glomerular filtration rate (GFR) > 60 ml/min/1.73 m2 was performed., Results: we included 181 patients aged ≥65 years and 104 younger patients. Mean age in the older group was 76.9 ± 8 years versus 50.9 ± 12.4 in the younger group. Vancomycin trough levels and 24-hours area under the curve to minimal inhibitory concentrations (AUC/MIC) were significantly higher in older patients who were also significantly more likely to achieve trough levels of ≥15 mg/l within 4 days, (98/181 (54.1%) vs. 38/104 (36.5%) in younger patients, P = 0.004). Results were similar among patients with GFR > 60. Thirty-day mortality was significantly higher in older (74/181, 40.9% vs. 13/104, 12.5%, respectively, P < 0.001). There was no association between vancomycin trough levels and mortality among older patients. No significant differences were demonstrated in clinical or microbiological success or nephrotoxicity., Conclusions: applying uniform dosing recommendations across age groups among adults with MRSA infections results in higher vancomycin levels and AUC/MIC in older versus younger patients. Yet, mortality rates remain higher among older adults. Prospective studies are needed to define the optimal approach for using this drug in older patients., (© The Author(s) 2019. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Gram-negative bacteremia is a major cause of morbidity and mortality in hospitalized patients. Data to guide the duration of antibiotic therapy are limited., Methods: This was a randomized, multicenter, open-label, noninferiority trial. Inpatients with gram-negative bacteremia, who were afebrile and hemodynamically stable for at least 48 hours, were randomized to receive 7 days (intervention) or 14 days (control) of covering antibiotic therapy. Patients with uncontrolled focus of infection were excluded. The primary outcome at 90 days was a composite of all-cause mortality; relapse, suppurative, or distant complications; and readmission or extended hospitalization (>14 days). The noninferiority margin was set at 10%., Results: We included 604 patients (306 intervention, 298 control) between January 2013 and August 2017 in 3 centers in Israel and Italy. The source of the infection was urinary in 411 of 604 patients (68%); causative pathogens were mainly Enterobacteriaceae (543/604 [90%]). A 7-day difference in the median duration of covering antibiotics was achieved. The primary outcome occurred in 140 of 306 patients (45.8%) in the 7-day group vs 144 of 298 (48.3%) in the 14-day group (risk difference, -2.6% [95% confidence interval, -10.5% to 5.3%]). No significant differences were observed in all other outcomes and adverse events, except for a shorter time to return to baseline functional status in the short-course therapy arm., Conclusions: In patients hospitalized with gram-negative bacteremia achieving clinical stability before day 7, an antibiotic course of 7 days was noninferior to 14 days. Reducing antibiotic treatment for uncomplicated gram-negative bacteremia to 7 days is an important antibiotic stewardship intervention., Clinical Trials Registration: NCT01737320., (© The Author(s) 2018. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: Early infections are common during the first month after liver transplantation (LT), whereas no consensus exists on the optimal prophylactic antimicrobial therapy. We aimed to evaluate the effectiveness of cefazolin perioperative prophylaxis in LT., Patients and Methods: We documented our experience with single-dose cefazolin as prophylaxis for LT. Infections occurring within 30 days following LT during 2006-2015 were documented retrospectively. Univariate and multivariate analyses of risk factors for infection were carried out., Results: Among 113 LT recipients receiving cefazolin as prophylaxis, infections occurred in 50 (44%) patients, including surgical site infections (n=24, 21%) and bacteremia (n=14, 12%). Bacteria resistant to cefazolin were documented in 59/72 (82%) isolates. Enterococcal infections were documented in 6% (7/113). Almost half of the infections (44%) occurred in the first week following LT and the vast majority within 2 weeks. The 30-day mortality rate (7%, 8/113) was significantly higher among infected patients (7/50, 14% vs. 1/63, 1.6%, P=0.011). Model for End-stage Liver Disease score, age, and requirement for at least 5 U of packed red cells during transplantation were predictive for postoperative infections., Conclusion: In our center, cefazolin was insufficient as perioperative prophylaxis in LT. We suggest that all LT recipients should receive antibiotic prophylaxis targeting microorganisms on the basis of local bacterial ecology and patterns of resistance irrespective of preoperative or intraoperative risk assessment.

Background: We evaluated the association between mortality and colistin resistance in Acinetobacter baumannii infections and the interaction with antibiotic therapy., Methods: This is a secondary analysis of a randomized controlled trial of patients with carbapenem-resistant gram-negative bacterial infections treated with colistin or colistin-meropenem combination. We evaluated patients with infection caused by carbapenem-resistant A. baumannii (CRAB) identified as colistin susceptible (CoS) at the time of treatment and compared patients in which the isolate was confirmed as CoS with those whose isolates were retrospectively identified as colistin resistant (CoR) when tested by broth microdilution (BMD). The primary outcome was 28-day mortality., Results: Data were available for 266 patients (214 CoS and 52 CoR isolates). Patients with CoR isolates had higher baseline functional capacity and lower rates of mechanical ventilation than patients with CoS isolates. All-cause 28-day mortality was 42.3% (22/52) among patients with CoR strains and 52.8% (113/214) among patients with CoS isolates (P = .174). After adjusting for variables associated with mortality, the mortality rate was lower among patients with CoR isolates (odds ratio [OR], 0.285 [95% confidence interval {CI}, .118-.686]). This difference was associated with treatment arm: Mortality rates among patients with CoR isolates were higher in those randomized to colistin-meropenem combination therapy compared to colistin monotherapy (OR, 3.065 [95% CI, 1.021-9.202])., Conclusions: Colistin resistance determined by BMD was associated with lower mortality among patients with severe CRAB infections. Among patients with CoR isolates, colistin monotherapy was associated with a better outcome compared to colistin-meropenem combination therapy., Clinical Trials Registration: NCT01732250., (© The Author(s) 2018. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Background: People with cancer with febrile neutropenia are at risk of severe infections and mortality and are thus treated empirically with broad-spectrum antibiotic therapy. However, the recommended duration of antibiotic therapy differs across guidelines., Objectives: To assess the safety of protocol-guided discontinuation of antibiotics regardless of neutrophil count, compared to continuation of antibiotics until neutropenia resolution in people with cancer with fever and neutropenia, in terms of mortality and morbidity. To assess the emergence of resistant bacteria in people with cancer treated with short courses of antibiotic therapy compared with people with cancer treated until resolution of neutropenia., Search Methods: We searched the Cochrane Central Register of Controlled Trials (CENTRAL; 2018, Issue 10) in the Cochrane Library, MEDLINE, Embase, and LILACS up to 1 October 2018. We searched the metaRegister of Controlled Trials and the US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov for ongoing and unpublished trials. We reviewed the references of all identified studies for additional trials and handsearched conference proceedings of international infectious diseases and oncology and haematology conferences., Selection Criteria: We included randomised controlled trials (RCTs) that compared a short antibiotic therapy course in which discontinuation of antibiotics was guided by protocols regardless of the neutrophil count to a long course in which antibiotics were continued until neutropenia resolution in people with cancer with febrile neutropenia. The primary outcome was 30-day or end of follow-up all-cause mortality., Data Collection and Analysis: Two review authors independently reviewed all studies for eligibility, extracted data, and assessed risk of bias for all included trials. We calculated risk ratios (RRs) with 95% confidence intervals (CIs) whenever possible. For dichotomous outcomes with zero events in both arms of the trials, we conducted meta-analysis of risk differences (RDs) as well. For continuous outcomes, we extracted means with standard deviations (SD) from the studies and computed mean difference (MD) and 95% CI. If no substantial clinical heterogeneity was found, trials were pooled using the Mantel-Haenszel fixed-effect model., Main Results: We included eight RCTs comprising a total of 662 distinct febrile neutropenia episodes. The studies included adults and children, and had variable design and criteria for discontinuation of antibiotics in both study arms. All included studies but two were performed before the year 2000. All studies included people with cancer with fever of unknown origin and excluded people with microbiological documented infections.We found no significant difference between the short-antibiotic therapy arm and the long-antibiotic therapy arm for all-cause mortality (RR 1.38, 95% CI 0.73 to 2.62; RD 0.02, 95% CI -0.02 to 0.05; low-certainty evidence). We downgraded the certainty of the evidence to low due to imprecision and high risk of selection bias. The number of fever days was significantly lower for people in the short-antibiotic treatment arm compared to the long-antibiotic treatment arm (mean difference -0.64, 95% CI -0.96 to -0.32; I² = 30%). In all studies, total antibiotic days were fewer in the intervention arm by three to seven days compared to the long antibiotic therapy. We found no significant differences in the rates of clinical failure (RR 1.23, 95% CI 0.85 to 1.77; very low-certainty evidence). We downgraded the certainty of the evidence for clinical failure due to variable and inconsistent definitions of clinical failure across studies, possible selection bias, and wide confidence intervals. There was no significant difference in the incidence of bacteraemia occurring after randomisation (RR 1.56, 95% CI 0.91 to 2.66; very low-certainty evidence), while the incidence of any documented infections was significantly higher in the short-antibiotic therapy arm (RR 1.67, 95% CI 1.08 to 2.57). There was no significant difference in the incidence of invasive fungal infections (RR 0.86, 95% CI 0.32 to 2.31) and development of antibiotic resistance (RR 1.49, 95% CI 0.62 to 3.61). The data on hospital stay were too sparse to permit any meaningful conclusions., Authors' Conclusions: We could make no strong conclusions on the safety of antibiotic discontinuation before neutropenia resolution among people with cancer with febrile neutropenia based on the existing evidence and its low certainty. Results of microbiological outcomes favouring long antibiotic therapy may be misleading due to lower culture positivity rates under antibiotic therapy and not true differences in infection rates. Well-designed, adequately powered RCTs are required that address this issue in the era of rising antibiotic resistance.

Background: Empirical colistin should be avoided. We aimed to evaluate the association between covering empirical antibiotics (EAT) and mortality for infections caused by carbapenem-resistant gram-negative bacteria (CRGNB)., Methods: This was a secondary analysis of a randomized controlled trial, including adults with bloodstream infections, pneumonia, or urosepsis caused by CRGNB. All patients received EAT followed by covering targeted therapy. The exposure variable was covering EAT in the first 48 hours. The outcome was 28-day mortality. We adjusted the analyses by multivariable regression analysis and propensity score matching., Results: The study included 406 inpatients with severe CRGNB infections, mostly Acinetobacter baumannii (312/406 [77%]). Covering EAT was given to 209 (51.5%) patients, mostly colistin (n = 200). Patients receiving noncovering EAT were older, more frequently unconscious and dependent, carrying catheters, and mechanically ventilated with pneumonia. Mortality was 84 of 197 (42.6%) with noncovering vs 96 of 209 (45.9%) with covering EAT (P = .504). Covering EAT was not associated with survival in the adjusted analysis; rather, there was a weak association with mortality (odds ratio [OR], 1.37; 95% confidence interval [CI], 1.02-1.84). Results were similar for colistin monotherapy and colistin-carbapenem combination EAT. In the propensity score-matched cohort (n = 338) covering antibiotics were not significantly associated with mortality (OR, 1.42; 95% CI, .91-2.22). Similar results were obtained in an analysis of 14-day mortality., Conclusions: Empirical use of colistin before pathogen identification, with or without a carbapenem, was not associated with survival following severe infections caused by CRGNBs, mainly A. baumannii.

Background: Bloodstream infections (BSIs) are an important cause of hospitalizations and mortality among hemodialysis (HD) patients. Epidemiology of these infections is changing, with increasing rates of Gram-negative pathogens, including resistant ones. Few studies have focused on the characteristics and outcomes of these infections., Objective: We aimed to document the causative pathogens of BSIs in HD patients and their clinical outcomes during 2008 - 2015, and to compare risk factors, clinical features, appropriateness of therapy, and outcomes between patients with Gram-negative vs. Gram-positive BSIs., Materials and Methods: A single-center retrospective cohort study. Charts of 120 HD patients hospitalized with first BSI were reviewed., Results: A total of 120 patients were included, 61 episodes of Gram-negative (51.8%) and 59 episodes of Gram-positive bacteria (49.2%). Source of infection was significantly more likely to be urinary or abdominal among patients with Gram-negative infection. Otherwise, no statistically significant differences were documented between groups in terms of baseline characteristics, presentation of infection and outcomes. Most Gram-negative BSIs were caused by enterobacteriaceae, followed by Pseudomonas spp. Previous clinical or surveillance cultures added little to accurate prediction of the causative organism., Conclusion: In a cohort of HD patients with BSI, no significant differences were found between Gram-negative and Gram-positive BSIs, besides source of infection. A urinary or abdominal source strongly suggests a Gram-negative pathogen. Otherwise, patient's characteristics, clinical presentation, and previous cultures, all cannot accurately predict the causative pathogen of BSI, and broad-spectrum antibiotics should be used empirically.
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Background: Ceftazidime/avibactam is approved for complicated intra-abdominal and urinary tract infections (UTIs) based on results from randomized controlled trials (RCTs). Data regarding its effectiveness in treating hospital-acquired infections or resistant pathogens have not been systematically compiled., Methods: A systematic review and meta-analysis including RCTs evaluating ceftazidime/avibactam versus comparator for the treatment of any infection. Primary outcome was 30 day all-cause mortality. Subgroups of hospital-acquired infections and specific resistance phenotypes were planned., Results: Seven publications (eight trials, 4093 patients) were included, reporting a baseline ∼25% of ESBL-carrying Enterobacteriaceae. No significant difference between ceftazidime/avibactam and comparator (mostly carbapenem) was demonstrated for 30 day all-cause mortality, late follow-up mortality and clinical response [relative risk (RR) 1.10, 95% CI 0.70-1.72, P = 0.69; RR 1.23, 95% CI 0.87-1.76, P = 0.25; RR 0.98, 95% CI 0.96-1.01, P = 0.21, respectively, without significant heterogeneity]. Higher microbiological response rate was demonstrated with ceftazidime/avibactam in patients with UTI (RR 1.14, 1.0-1.29, P = 0.05, I2 = 51%). No significant difference in clinical response was demonstrated for patients with ceftazidime-resistant pathogens (RR 1.02, 95% CI 0.94-1.10, P = 0.66, I2 = 0%). Results for other subgroups of resistant pathogens or hospital-acquired infection were not available. Serious adverse events (SAEs) were significantly more common with ceftazidime/avibactam (RR 1.24, 95% CI 1.00-1.54, P = 0.05, I2 = 0%)., Conclusions: Ceftazidime/avibactam is clinically and microbiologically as effective as carbapenems for treatment of infections in a setting of ∼25% ESBL-carrying Enterobacteriaceae. Safety of the drug should be further evaluated owing to a higher rate of SAEs compared with carbapenems. Further studies should assess the drug's effectiveness in the treatment of carbapenemase-producing Enterobacteriaceae.

Background: Colistin-carbapenem combinations are synergistic in vitro against carbapenem-resistant Gram-negative bacteria. We aimed to test whether combination therapy improves clinical outcomes for adults with infections caused by carbapenem-resistant or carbapenemase-producing Gram-negative bacteria., Methods: A randomised controlled superiority trial was done in six hospitals in Israel, Greece, and Italy. We included adults with bacteraemia, ventilator-associated pneumonia, hospital-acquired pneumonia, or urosepsis caused by carbapenem-non-susceptible Gram-negative bacteria. Patients were randomly assigned (1:1) centrally, by computer-generated permuted blocks stratified by centre, to intravenous colistin (9-million unit loading dose, followed by 4·5 million units twice per day) or colistin with meropenem (2-g prolonged infusion three times per day). The trial was open-label, with blinded outcome assessment. Treatment success was defined as survival, haemodynamic stability, improved or stable Sequential Organ Failure Assessment score, stable or improved ratio of partial pressure of arterial oxygen to fraction of expired oxygen for patients with pneumonia, and microbiological cure for patients with bacteraemia. The primary outcome was clinical failure, defined as not meeting all success criteria by intention-to-treat analysis, at 14 days after randomisation. This trial is registered at ClinicalTrials.gov, number NCT01732250, and is closed to accrual., Findings: Between Oct 1, 2013, and Dec 31, 2016, we randomly assigned 406 patients to the two treatment groups. Most patients had pneumonia or bacteraemia (355/406, 87%), and most infections were caused by Acinetobacter baumannii (312/406, 77%). No significant difference between colistin monotherapy (156/198, 79%) and combination therapy (152/208, 73%) was observed for clinical failure at 14 days after randomisation (risk difference -5·7%, 95% CI -13·9 to 2·4; risk ratio [RR] 0·93, 95% CI 0·83-1·03). Results were similar among patients with A baumannii infections (RR 0·97, 95% CI 0·87-1·09). Combination therapy increased the incidence of diarrhoea (56 [27%] vs 32 [16%] patients) and decreased the incidence of mild renal failure (37 [30%] of 124 vs 25 [20%] of 125 patients at risk of or with kidney injury)., Interpretation: Combination therapy was not superior to monotherapy. The addition of meropenem to colistin did not improve clinical failure in severe A baumannii infections. The trial was unpowered to specifically address other bacteria., Funding: EU AIDA grant Health-F3-2011-278348., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The objective of this study was to explore whether the percentage of inappropriate empirical antibiotic treatment in patients with bacteremia changed over time and to understand the factors that brought on the change. Three prospective cohorts of patients with bacteremia in three different periods (January 1st, 1988 to December 31st, 1989; May 1st, 2004 to November 30, 2004; May 1st, 2010 to April 30, 2011) were compared. Analysis was performed on a total of 811 patients. In 2010-2011, 55.9% (76/136) of patients with bacteremia received inappropriate empirical treatment, compared with 34.5% (170/493) and 33.5% (55/164) in the first and second periods, respectively, in a significant upward trend (p = 0.001). Resistance to antibiotics increased significantly during the study period. The following variables were included in the multivariate analysis assessing risk factors for inappropriate empirical treatment: study period (third period) [odds ratio, OR = 2.766 (95% confidence interval, CI, 1.655-4.625)], gender (male) [OR = 1.511 (1.014-2.253)], pathogen carrying extended-spectrum beta-lactamases [OR = 10.426 (4.688-23.187)], multidrug-resistant Acinetobacter baumannii [OR = 5.428 (2.181-13.513)], and skin/soft infections [OR = 3.23 (1.148-9.084)]. A model excluding microbiological data included: gender (male) [OR = 1.648 (1.216-2.234)], study period (third period) [OR = 2.446 (1.653-3.620)], hospital-acquired infection [OR = 1.551 (1.060-2.270)], previous use of antibiotics [OR = 1.815 (1.247-2.642)], bedridden patient [OR = 2.019 (1.114-3.658)], and diabetes mellitus [OR = 1.620 (1.154-2.274)]. We have observed a worrisome increase in the rate of inappropriate empirical treatment of bacteremia. We need tools that will allow us better prediction of the pathogen and its susceptibilities during the first hours of managing a patient suspected of a severe bacterial infection.

Objectives: Therapeutic options available to treat MRSA pneumonia are limited. Trimethoprim/sulfamethoxazole is an attractive treatment because of its bactericidal anti-MRSA activity, oral and parenteral formulations and good penetration to the lung tissue. We aimed to compare the efficacy and safety of trimethoprim/sulfamethoxazole with vancomycin in the treatment of healthcare/ventilator-associated MRSA pneumonia., Methods: We carried out a retrospective case-control study of all consecutive hospitalized adult patients diagnosed with MRSA pneumonia at Beilinson Hospital during 2010-15 and treated with either vancomycin or trimethoprim/sulfamethoxazole. The primary outcomes were all-cause mortality at 30 days and clinical failure at the end of treatment. In order to reduce bias affecting the decision to use a specific antibiotic and as a sensitivity analysis, a propensity-score model for choosing between vancomycin and trimethoprim/sulfamethoxazole was used., Results: We identified 42 patients with MRSA pneumonia treated with trimethoprim/sulfamethoxazole and 39 treated with vancomycin. There were no significant differences in the baseline characteristics between the groups. Vancomycin-treated patients showed significantly higher 30 day mortality on both multivariate analysis (HR = 5.28; 95% CI = 1.50-18.60; P  < 0.05) and sensitivity analysis with propensity score [vancomycin 13/24 (54.1%) versus trimethoprim/sulfamethoxazole 4/24 (16.7%); P  < 0.05], and higher clinical failure rates [vancomycin 23/39 (59%) versus trimethoprim/sulfamethoxazole 15/42 (35.7%); P  < 0.05], also in the sensitivity analysis with propensity score [vancomycin 14/24 (58.3%) versus trimethoprim/sulfamethoxazole 6/24 (25%); P  < 0.05]. The rates of side effects in both arms were comparable., Conclusions: Trimethoprim/sulfamethoxazole appears to be superior to vancomycin in the treatment of MRSA pneumonia. A large-scale randomized controlled trial is needed to evaluate these findings., (© The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background:  Optimizing colistin dosing should translate to improved patient outcomes., Methods:  We used data from 2 prospective cohort studies performed between 2006 and 2009 and between 2012 and 2015. In the latter period, a new policy of high-dose colistin (9 million international units [MIU] loading dose followed by 9 MIU daily for normal renal function) was introduced in 2 participating hospitals. We included adult inpatients with invasive infections caused by carbapenem-resistant gram-negative bacteria treated with colistin. Our primary exposure variable was colistin dose, dichotomized to high-dose vs other regimens. The primary outcome was 28-day mortality. We generated a propensity score for high-dose colistin and conducted propensity-adjusted multivariable and matched-cohort analyses for mortality., Results:  Of 529 consecutive patients fulfilling inclusion criteria, 144 were treated with high-dose colistin and 385 with lower-dose colistin regimens. The median daily dose in the high-dose group was 9 MIU (interquartile range [IQR], 9-9) vs 4 MIU (IQR, 3-6) with other regimens. There were 50 of 144 (34.7%) deaths with high-dose colistin vs 165 of 385 (42.9%) with low-dose colistin (P = .1). The propensity-adjusted odds ratio (OR) for mortality was 1.07 (95% confidence interval [CI], .63-1.83) for high-dose colistin. Similar results were obtained when using the study period as the exposure variable, in the subgroup of bacteremic patients (n = 207) and in the propensity-matched cohort (OR, 1.11 [95% CI, .67-1.82]). Nephrotoxicity (RIFLE injury or higher; OR, 2.12 [95% CI, 1.29-3.48]; n = 396) and seizures were significantly more common with high-dose colistin., Conclusions:  In a large cohort, we found no association between high colistin dosing and all-cause mortality. High dosing was associated with more nephrotoxicity., (© The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.)

Antibiotics are among the most important interventions in healthcare. Resistance of bacteria to antibiotics threatens the effectiveness of treatment. Systematic reviews of antibiotic treatments often do not address resistance to antibiotics even when data are available in the original studies. This omission creates a skewed view, which emphasizes short-term efficacy and ignores the long-term consequences to the patient and other people. We offer a framework for addressing antibiotic resistance in systematic reviews. We suggest that the data on background resistance in the original trials should be reported and taken into account when interpreting results. Data on emergence of resistance (whether in the body reservoirs or in the bacteria causing infection) are important outcomes. Emergence of resistance should be taken into account when interpreting the evidence on antibiotic treatment in randomized controlled trials or systematic reviews., (© The Author 2016. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

Introduction: The emergence of antibiotic-resistant bacteria has driven renewed interest in older antibacterials, including colistin. Previous studies have shown that colistin is less effective and more toxic than modern antibiotics. In vitro synergy studies and clinical observational studies suggest a benefit of combining colistin with a carbapenem. A randomised controlled study is necessary for clarification., Methods and Analysis: This is a multicentre, investigator-initiated, open-label, randomised controlled superiority 1:1 study comparing colistin monotherapy with colistin-meropenem combination therapy for infections caused by carbapenem-resistant Gram-negative bacteria. The study is being conducted in 6 centres in 3 countries (Italy, Greece and Israel). We include patients with hospital-associated and ventilator-associated pneumonia, bloodstream infections and urosepsis. The primary outcome is treatment success at day 14, defined as survival, haemodynamic stability, stable or improved respiratory status for patients with pneumonia, microbiological cure for patients with bacteraemia and stability or improvement of the Sequential Organ Failure Assessment (SOFA) score. Secondary outcomes include 14-day and 28-day mortality as well as other clinical end points and safety outcomes. A sample size of 360 patients was calculated on the basis of an absolute improvement in clinical success of 15% with combination therapy. Outcomes will be assessed by intention to treat. Serum colistin samples are obtained from all patients to obtain population pharmacokinetic models. Microbiological sampling includes weekly surveillance samples with analysis of resistance mechanisms and synergy. An observational trial is evaluating patients who met eligibility requirements but were not randomised in order to assess generalisability of findings., Ethics and Dissemination: The study was approved by ethics committees at each centre and informed consent will be obtained for all patients. The trial is being performed under the auspices of an independent data and safety monitoring committee and is included in a broad dissemination strategy regarding revival of old antibiotics., Trial Registration Number: NCT01732250 and 2012-004819-31; Pre-results., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Background: Methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia is a serious infection resulting in 20-50 % 90-day mortality. The limitations of vancomycin, the current standard therapy for MRSA, make treatment difficult. The only other approved drug for treatment of MRSA bacteraemia, daptomycin, has not been shown to be superior to vancomycin. Surprisingly, there has been consistent in-vitro and in-vivo laboratory data demonstrating synergy between vancomycin or daptomycin and an anti-staphylococcal β-lactam antibiotic. There is also growing clinical data to support such combinations, including a recent pilot randomised controlled trial (RCT) that demonstrated a trend towards a reduction in the duration of bacteraemia in patients treated with vancomycin plus flucloxacillin compared to vancomycin alone. Our aim is to determine whether the addition of an anti-staphylococcal penicillin to standard therapy results in improved clinical outcomes in MRSA bacteraemia., Methods/design: We will perform an open-label, parallel-group, randomised (1:1) controlled trial at 29 sites in Australia, New Zealand, Singapore, and Israel. Adults (aged 18 years or older) with MRSA grown from at least one blood culture and able to be randomised within 72 hours of the index blood culture collection will be eligible for inclusion. Participants will be randomised to vancomycin or daptomycin (standard therapy) given intravenously or to standard therapy plus 7 days of an anti-staphylococcal β-lactam (flucloxacillin, cloxacillin, or cefazolin). The primary endpoint will be a composite outcome at 90 days of (1) all-cause mortality, (2) persistent bacteraemia at day 5 or beyond, (3) microbiological relapse, or (4) microbiological treatment failure. The recruitment target of 440 patients is based on an expected failure rate for the primary outcome of 30 % in the control arm and the ability to detect a clinically meaningful absolute decrease of 12.5 %, with a two-sided alpha of 0.05, a power of 80 %, and assuming 10 % of patients will not be evaluable for the primary endpoint., Discussion: Key potential advantages of adding anti-staphylococcal β-lactams to standard therapy for MRSA bacteraemia include their safety profile, low cost, and wide availability., Trial Registration: ClinicalTrials.gov Identifier: NCT02365493 . Registered 24 February 2015.

Objectives: To assess the external validity of a pragmatic, investigator-initiated RCT on treatment of severe infections caused by methicillin-resistant Staphylococcus aureus (MRSA), we compared patient characteristics and treatment effect estimates for patients included in the RCT versus those excluded., Participants and Outcomes: The RCT included hospitalised patients with documented or highly-probable invasive MRSA infections who were randomised to vancomycin versus trimethoprim-sulfamethoxazole (TMP-SMX) treatment, between 2007 and 2014. A concomitant observational study prospectively included all consecutive patients, between 2008 and 2011, who were excluded from the RCT due to no consent, meningitis, left-sided endocarditis, severe neutropaenia, chronic renal dialysis or treatment with study medications for longer than 48 h. The primary outcomes were clinical failure at day 7 and 30-day mortality for both studies. We compared baseline and infection characteristics, outcome rates and treatment effect estimates for included versus excluded patients., Results: The RCT included 252 patients who were compared with 220 excluded patients who were observed. Inability to provide informed consent was the main reason for patient exclusion. Excluded patients' functional and cognitive performance was significantly poorer than that of included patients. Sepsis was more severe among excluded patients (higher rates of mechanical ventilation, indwelling catheters, septic shock and organ failure). Clinical failure occurred in 83/252 (32.9%) versus 175/220 (79.5%) and deaths in 32 (12.7%) versus 64 (29.1%) for included versus excluded patients, p<0.001 for both comparisons. Comparing vancomycin to TMP-SMX, in the RCT mortality, was non-significantly lower with vancomycin (OR 0.76, 95% CIs 0.36 to 1.62), while in the observational analysis of excluded patients, mortality was significantly higher with vancomycin (OR 2.63, 1.04 to 6.65), p=0.04 for the difference., Conclusions: Patient characteristics, outcome event rates and treatment effects differed significantly in the setting of a RCT, despite its pragmatic design, compared to patients treated outside the trial settings., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)

Objective: To show non-inferiority of trimethoprim-sulfamethoxazole compared with vancomycin for the treatment of severe infections due to meticillin resistant Staphylococcus aureus (MRSA)., Design: Parallel, open label, randomised controlled trial., Setting: Four acute care hospitals in Israel., Participants: Adults with severe infections caused by MRSA susceptible to trimethoprim-sulfamethoxazole and vancomycin. Patients with left sided endocarditis, meningitis, chronic haemodialysis, and prolonged neutropenia were excluded., Interventions: Trimethoprim-sulfamethoxazole 320 mg/1600 mg twice daily versus vancomycin 1 g twice daily for a minimum of seven days and then by indication., Main Outcome Measures: The primary efficacy outcome was treatment failure assessed at day 7, consisting of death, persistence of haemodynamic instability or fever, stable or worsening Sequential Organ Failure Assessment score, and persistence of bacteraemia. The primary safety outcome was all cause mortality at day 30. Non-inferiority was defined by a difference of less than 15% for treatment failure., Results: 252 patients were included in the trial, of whom 91 (36%) had bacteraemia. No significant difference in treatment failure was seen for trimethoprim-sulfamethoxazole (51/135, 38%) versus vancomycin (32/117, 27%)-risk ratio 1.38 (95% confidence interval 0.96 to 1.99). However, trimethoprim-sulfamethoxazole did not meet the non-inferiority criterion-absolute difference 10.4% (95% confidence interval -1.2% to 21.5%). For patients with bacteraemia, the risk ratio was 1.40 (0.91 to 2.16). In a multivariable logistic regression analysis, trimethoprim-sulfamethoxazole was significantly associated with treatment failure (adjusted odds ratio 2.00, 1.09 to 3.65). The 30 day mortality rate was 32/252 (13%), with no significant difference between arms. Among patients with bacteraemia, 14/41 (34%) treated with trimethoprim-sulfamethoxazole and 9/50 (18%) with vancomycin died (risk ratio 1.90, 0.92 to 3.93)., Conclusions: High dose trimethoprim-sulfamethoxazole did not achieve non-inferiority to vancomycin in the treatment of severe MRSA infections. The difference was particularly marked for patients with bacteraemia. Trial registration Clinical trials NCT00427076., (© Paul et al 2015.)

Background: Acute pyelonephritis is a frequent cause of morbidity, with a wide variation in duration of therapy. We performed a systematic review of all randomized controlled trials (RCTs) comparing ≤7 days treatment with a longer course., Methods: Electronic databases were searched to identify RCTs that assessed adults treated for pyelonephritis, comparing a 7 day or shorter versus longer therapy. Primary outcome was clinical failure at the end of the long treatment arm (EOT). Secondary outcomes included clinical failure at the end of follow-up (EOF), microbiological failure, all-cause mortality, the development of resistance and adverse events., Results: Clinical failure at EOT did not significantly differ between the two treatment arms [relative risk (RR) 0.63, 95% CI 0.33-1.18, I(2) = 41%]. Results did not differ when including studies comparing only fluoroquinolones, reducing the heterogeneity (RR 0.76, 95% CI 0.49-1.17, I(2) = 0%). We found no difference between the short and long treatment arms regarding clinical failure at EOF, even in a small subgroup of bacteraemic patients. No difference was found between the arms regarding microbiological failure at EOF, except in a subgroup of studies with a high percentage of patients with urogenital abnormalities, where microbiological failure at EOF was significantly higher in the short treatment arm (RR 1.78, 95% CI 1.02-3.10, I(2) = 21%). Adverse events were similar between the arms., Conclusions: Seven days of treatment for acute pyelonephritis is equivalent to longer treatment in terms of clinical failure and microbiological failure, including in bacteraemic patients. In patients with urogenital abnormalities, the evidence, although weak, suggests that longer treatment is required.

Time to first antibiotic dose (TFAD) of 4h or 8h has been suggested as a quality measure for adult patients hospitalised with community-acquired pneumonia (CAP). Clinical evidence leading to implementation of this quality measure came from two large, retrospective studies. Following these studies, several prospective studies were conducted, with variable results. In a compilation of all observational studies to date, no significant benefit for short TFAD in terms of all-cause mortality was observed [unadjusted odds ratio (OR) = 1.01, 95% confidence interval (CI) 0.79-1.29, 13 studies; adjusted OR = 0.95, 95% CI 0.73-1.23, 14 studies]. Implementation of a requirement for short TFAD for CAP in the emergency department or other acute medical care setting may lead to unnecessary antibiotic treatment. We believe that attention should be shifted to early appropriate empirical antibiotic treatment for severe sepsis in hospital regardless of the source of infection, rather than focusing on CAP., (Copyright © 2013 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.)

Background: Tigecycline is a novel glycylcycline that exhibits broad-spectrum antibacterial activity. Recently, the US FDA issued a warning concerning increased mortality with tigecycline in randomized controlled trials (RCTs)., Methods: We conducted a systematic review and meta-analysis of RCTs that compared tigecycline with any other antibiotic regimen for the treatment of any infection. A comprehensive search, without publication status or other restrictions, was conducted. The primary outcome was overall 30 day mortality. The secondary outcome included clinical and microbiological failure, superinfections and adverse events (AEs). The trials' risks of bias and their effects on results were assessed. Two reviewers independently extracted the data. Individual trials' relative risks (RRs) were pooled using a fixed effect meta-analysis., Results: Fifteen trials (7654 patients) were included. Overall mortality was higher with tigecycline compared with other regimens [RR 1.29, 95% confidence interval (CI) 1.02-1.64, without heterogeneity]. The type of infection assessed and the trials' reported risks of bias did not affect this result. Clinical failure was significantly higher with tigecycline (RR 1.16, 95% CI 1.06-1.27) and non-statistically significant higher rates of microbiological failure were demonstrated (RR 1.13, 95% CI 0.99-1.30). Development of septic shock was significantly more frequent with tigecycline (RR 7.01, 95% CI 1.27-38.66). Superinfections were significantly more common with tigecycline and so were AEs, including all AEs and AEs requiring discontinuation., Conclusions: In the light of the increased mortality, probably explained by decreased clinical and microbiological efficacy, clinicians should avoid tigecycline monotherapy in the treatment of severe infections and reserve it as a last-resort drug.

Background: Several beta-lactams are recommended as single agents for the treatment of febrile neutropenia., Objectives: To compare the effectiveness of different anti-pseudomonal beta-lactams as single agents in the treatment of febrile neutropenia. To compare the development of bacterial resistance, bacterial and fungal superinfections during or following treatment with the different beta-lactams., Search Strategy: We searched the Cochane Register of Controlled Trials (CENTRAL), Issue 3, 2010. MEDLINE, EMBASE, LILACS, FDA drug applications, conference proceedings and ongoing clinical trial databases up to August 2010. References of included studies were scanned., Selection Criteria: Randomised controlled trials (RCTs) comparing an antipseudomonal beta-lactam to another antipseudomonal beta-lactam antibiotic, both given alone or with the addition of the same glycopeptide to both study arms, for the initial treatment of fever and neutropenia among cancer patients., Data Collection and Analysis: Two review authors applied inclusion criteria and extracted the data independently. Missing data were sought. Risk ratios (RR) were calculated with 95% confidence intervals (CI), and pooled using the fixed effect model. The primary outcome was all-cause mortality. Risk of bias was assessed using a domain-based evaluation and its effect of results was assessed through sensitivity analyses., Main Results: Forty-four trials were included. The antibiotics assessed were cefepime, ceftazidime, piperacillin-tazobactam, imipenem and meropenem. Adequate allocation concealment and generation were reported in about half of the trials and only two trials were double-blinded. The risk for all-cause mortality was significantly higher with cefepime compared to other beta-lactams (RR 1.39, 95% CI 1.04 to 1.86, 21 trials, 3471 participants), without heterogeneity and with higher RRs in trials at low risk for bias. There were no differences in secondary outcomes but for a non-significantly higher rate of bacterial superinfections with cefepime. Mortality was significantly lower with piperacillin-tazobactam compared to other antibiotics (RR 0.56, 95% CI 0.34 to 0.92, 8 trials, 1314 participants), without heterogeneity. Carbapenems resulted in similar all-cause mortality and a lower rate of clinical failure and antibiotic modifications as compared to other antibiotics, but a higher rate of diarrhea caused by Clostridium difficile., Authors' Conclusions: Current evidence supports the use of piperacillin-tazobactam in locations where antibiotic resistance profiles do not mandate empirical use of carbapenems. Carbapenems result in a higher rate of antibiotic-associated and Clostridium difficile-associated diarrhea. There is a high level of evidence that all-cause mortality is higher with cefepime compared to other beta-lactams and it should not be used as monotherapy for patients with febrile neutropenia.

Background: Colistin has re-entered clinical use by necessity. We aimed to assess its effectiveness and safety compared with newer antibiotics., Methods: This was a single-centre, prospective cohort study. Inclusion criteria were microbiologically documented pneumonia, urinary tract infection, surgical site infection, meningitis or bacteraemia treated appropriately with colistin versus imipenem, meropenem or ampicillin/sulbactam (comparators). All consecutive patients were included, only once, between May 2006 and July 2009. The primary outcome was 30 day mortality. Multivariable and Cox regression survival analyses were used to adjust comparisons between groups. Odds ratios (ORs) or hazard ratios (HRs) with 95% confidence intervals are reported., Results: Two hundred patients treated with colistin and 295 patients treated with comparators were included. Treatment with colistin was associated with older age, admission from healthcare facilities, mechanical ventilation and lower rate of early appropriate antibiotic treatment. The 30 day mortality was 39% (78/200) for colistin versus 28.8% (85/295) for comparators; unadjusted OR 1.58 (1.08-2.31). In the adjusted analysis the OR was 1.44 (0.91-2.26) overall and 1.99 (1.06-3.77) for bacteraemic patients (n = 220). At the end of follow-up, treatment with colistin was significantly associated with cumulative mortality; adjusted HR 1.27 (1.01-1.60) overall and 1.65 (1.18-2.31) among patients with bacteraemia. Nephrotoxicity at the end of treatment was more frequent with colistin; OR adjusted for other risk factors for nephrotoxicity 3.31 (1.54-7.08). Treatment with colistin was followed by increased incidence of Proteus spp. infections during a 3 month follow-up., Conclusions: The need for colistin treatment is associated with poorer survival. Adjusted analyses suggest that colistin is less effective and more toxic than beta-lactam antibiotics.

Objectives: To determine and quantify differences in efficacy between treatment regimens for brucellosis., Design: Systematic review and meta-analysis of randomised controlled trials assessing different antibiotic regimens and durations of treatment for human brucellosis., Data Sources: PubMed, CENTRAL, Lilacs, conference proceedings, and bibliographies with no restrictions on language, study year, or publication status. Review methods Search, application of inclusion and exclusion criteria, data extraction, and assessment of methodological quality independently performed in duplicate. Primary outcomes were relapse and overall failure resulting from primary failure or relapse. Relative risks with 95% confidence intervals were calculated and pooled with a fixed effect model., Results: 30 trials and 77 treatment arms were included. Overall failure was significantly higher with doxycycline-rifampicin compared to doxycycline-streptomycin, mainly due to a higher rate of relapse (relative risk 2.80, 95% confidence interval 1.81 to 4.36; 13 trials, without heterogeneity). Results were consistent among patients with bacteraemia and complicated brucellosis. Doxycycline-streptomycin resulted in a significantly higher rate of failure than doxycycline-rifampicin-aminoglycoside (triple drug regimen) (2.50, 1.26 to 5.00; two trials). Gentamicin was not inferior to streptomycin (1.45, 0.52 to 4.00 for failure; two trials). Quinolones combined with rifampicin were significantly less effective than doxycycline combined with rifampicin or streptomycin (1.83, 1.11 to 3.02, for failure; five trials). Monotherapy was associated with a higher risk of failure than combined treatment when administered for a similar duration (2.56, 1.55 to 4.23; five trials). Treatment for six weeks or more offered an advantage over shorter treatment durations., Conclusions: There are significant differences in effectiveness between currently recommended treatment regimens for brucellosis. The preferred treatment should be with dual or triple regimens including an aminoglycoside.

Cefepime is a broad-spectrum cephalosporin with enhanced coverage against Gram-positive and Gram-negative bacteria. We did a systematic review of randomised trials that compared cefepime with another beta-lactam antibiotic, alone or with the addition of a non-beta-lactam antibiotic to both study groups. We searched Central, PubMed, Embase, Lilacs, new US Food and Drug Administration drug applications, conference proceedings, and references of the included studies. Two reviewers independently did the search and data extraction. 57 trials were included. All-cause mortality-the primary outcome-was higher with cefepime than other beta-lactams (risk ratio [RR] 1.26 [95% CI 1.08-1.49]). Sensitivity analyses by the trials' methodological quality revealed higher RRs for trials reporting adequate allocation-sequence generation (1.52 [1.20-1.92]) and allocation concealment (1.36 [1.09-1.70]). Baseline risk factors for mortality were similar. No significant differences between groups in treatment failure, superinfection, or adverse events were found. This Review provides evidence and offers possible explanations for increased mortality among patients treated with cefepime in randomised trials.

Objectives: Early, empirical broad-spectrum antibiotic treatment is the established practice for febrile neutropenia. Several beta-lactams are accepted for monotherapy. We asked whether patients' outcomes are influenced by the chosen beta-lactam., Methods: Systematic review and meta-analysis of randomized controlled trials comparing anti-pseudomonal beta-lactams administered as empirical monotherapy for febrile neutropenia, with or without vancomycin. The search included The Cochrane Library, PubMed, Embase, Lilacs databases, bibliography, conference proceedings, trial registries and FDA new drug approvals. Two reviewers independently applied selection criteria, performed quality assessment and extracted the data. Trials assessing the same beta-lactam were pooled using the fixed effect model. Relative risks (RRs) with 95% confidence intervals (CIs) were calculated. The primary outcome assessed was all-cause mortality., Results: Thirty-three trials fulfilled inclusion criteria. Cefepime was associated with higher all-cause mortality at 30 days than other beta-lactams (RR 1.44, 95% CI 1.06-1.94, 3123 participants). Carbapenems were associated with fewer treatment modifications, including addition of glycopeptides, than ceftazidime or other comparators. Adverse events were significantly more frequent with carbapenems, specifically pseudomembranous colitis (RR 1.94, 95% CI 1.24-3.04, 2025 participants). All-cause mortality was unaltered. Piperacillin/tazobactam was compared only with cefepime and carbapenems, in six trials. No significant differences were demonstrated with paucity of data for all-cause mortality., Conclusions: The use of cefepime for febrile neutropenia is associated with increased mortality and should be carefully considered pending further analysis. Empirical use of carbapenems entails fewer treatment modifications, but an increased rate of pseudomembranous colitis. Ceftazidime, piperacillin/tazobactam, imipenem/cilastatin and meropenem appear to be suitable agents for monotherapy.

Staphylococcus aureus bloodstream (SAB) infection is a common and severe infectious disease, with a 90-day mortality of 15%-30%. Despite this,

BackgroundDesirability of outcome ranking (DOOR) is an innovative approach in clinical trials to evaluate the global benefits and risks of an intervention. We developed and validated a DOOR endpoint for Staphylococcus aureus bloodstream infection (BSI) through a survey to infectious diseases clinicians and secondary analysis of trial data.MethodsWe administered a survey of 20 cases of S. aureus BSI, asking respondents to rank outcomes by global desirability. Correlations and percentage of pairwise agreement among rankings were estimated to inform development of a DOOR endpoint, which was applied to 2 prior S. aureus BSI trials. The probability that a patient randomly assigned to experimental treatment would have a better DOOR ranking than if assigned to control was estimated. Results were also analyzed using partial credit, which is analogous to scoring an academic test, assigning 100% to the most desirable outcome, 0% to the least, and "partial credit" to intermediate ranks.ResultsForty-two recipients (97%) completed the survey. The DOOR endpoint fitting these rankings (r = 0.89; 95% confidence interval, 0.67 to 0.94) incorporated survival plus cumulative occurrence of adverse events, cure, infectious complications, and ongoing symptoms. Tailored versions of this endpoint were applied to 2 S. aureus BSI trials, and both demonstrated no benefit of the experimental treatment using DOOR and partial credit analysis.ConclusionsUsing S. aureus BSI as an exemplar, we developed a DOOR endpoint that can be used as a template for development of DOOR endpoints for other diseases. Future trials can incorporate DOOR to allow for global assessment of patient experience.