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Background To understand the clinical, bacterial, and host characteristics associated with recurrent Staphylococcus aureus bacteremia (R-SAB), patients with R-SAB were compared to contemporaneous patients with a single episode of SAB (S-SAB). Methods All SAB isolates underwent spa genotyping. All isolates from R-SAB patients underwent pulsed-field gel electrophoresis (PFGE). PFGE-indistinguishable pairs from 40 patients underwent whole genome sequencing (WGS). Acute phase plasma from R-SAB and S-SAB patients was matched 1:1 for age, race, sex, and bacterial genotype, and underwent cytokine quantification using 25-analyte multiplex bead array. Results R-SAB occurred in 69 (9.1%) of the 756 study patients. Of the 69 patients, 30 experienced relapse (43.5%) and 39 reinfection (56.5%). Age, race, hemodialysis dependence, presence of foreign body, methicillin-resistant Staphyloccus aureus, and persistent bacteremia were individually associated with likelihood of recurrence. Multivariate risk modeling revealed that black hemodialysis patients were nearly 2 times more likely (odds ratio [OR] = 9.652 [95% confidence interval [CI], 5.402–17.418]) than white hemodialysis patients (OR = 4.53 [95% CI, 1.696–10.879]) to experience R-SAB. WGS confirmed PFGE interpretations in all cases. Median RANTES (regulated on activation, normal T cell expressed and secreted) levels in acute phase plasma from the initial episode of SAB were higher in R-SAB than in matched S-SAB controls (P = .0053, false discovery rate Conclusion This study identified several risk factors for R-SAB. The largest risk for R-SAB is among black hemodialysis patients. Higher RANTES levels in R-SAB compared to matched controls warrants further study.

Background We conducted a longitudinal study to evaluate changes in the clinical presentation and epidemiology of Staphylococcus aureus bacteremia (SAB) in an academic, US medical center. Methods Consecutive patients with monomicrobial SAB were enrolled from January 1995 to December 2015. Each person’s initial bloodstream S. aureus isolate was genotyped using spa typing. Clonal complexes (CCs) were assigned using Ridom StaphType software. Changes over time in both the patient and bacterial characteristics were estimated with linear regression. Associations between genotypes or clinical characteristics and complications were estimated using multivariable regression models. Results Among the 2348 eligible participants, 54.2% had an implantable, foreign body of some type. This proportion increased significantly during the 21-year study period, by 0.96% annually (P = .002), as did comorbid conditions and acquisition outside of the hospital. Rates of any metastatic complication also significantly increased, by 0.94% annually (P = .019). Among the corresponding bloodstream S. aureus isolates, spa-CC012 (multi-locus sequence type [MLST] CC30), -CC004 (MLST CC45), -CC189 (MLST CC1), and -CC084 (MLST CC15) all significantly declined during the study period, while spa-CC008 (MLST CC8) significantly increased. Patients with SAB due to spa-CC008 were significantly more likely to develop metastatic complications in general, and abscesses, septic emboli, and persistent bacteremia in particular. After adjusting for demographic, racial, and clinical variables, the USA300 variant of spa-CC008 was independently associated with metastatic complications (odds ratio 1.42; 95% confidence interval 1.02–1.99). Conclusions Systematic approaches for monitoring complications of SAB and genotyping the corresponding bloodstream isolates will help identify the emergence of hypervirulent clones and likely improve clinical management of this syndrome.

Introduction: The burden of antimicrobial resistance among Gram-negative bacteria is increasing and growing into a major threat of public health. Treatment options for carbapenem-resistant Enterobacteriaceae are limited and resistance rates to existing compounds are mounting. The pipeline includes only a small number of novel anti-infective agents in development or in the market with promising results against multidrug-resistant (MDR) Gram-negative. Areas covered: Herein the authors present the modern available knowledge regarding novel β-lactam-β-lactamase inhibitors, i.e. mechanisms of action, in vitro activity, current PK/PDs, clinical trials and clinical efficacy against MDR and XDR Gram-negatives, as well as toxicity issues. Expert opinion: Ceftazidime-avibactam and meropenem-vaborbactam are promising therapeutic options as both are active against Enterobacteriaceae producing ESBL, AmpC, and KPC, whereas only avibactam inhibits certain class D β-lactamases, mainly OXA-48. New drugs active against Gram-negative MDR isolates including imipenem/cilastatin with relebactam and avibactam combined with aztreonam or ceftaroline are in different stages of development. However, the disadvantage to be seriously considered by the clinician is that β-lactam/β-lactamase inhibitors are ineffective against metallo-β-lactamases (with the exception of aztreonam-avibactam) as well as Acinetobacter baumannii.

Objectives Colistin is often the last option to treat infections caused by multidrug-resistant micro-organisms such as carbapenem-resistant Klebsiella pneumoniae. Antimicrobial susceptibility testing of colistin has been fraught with difficulties, which resulted in the need for updated recommendations from the CLSI and EUCAST. Both committees proposed that the ISO 20776-1-2016 standard broth microdilution (BMD) method must be the preferred method for colistin minimum inhibitory concentration (MIC) testing. The objective of this study was to evaluate the commercial ComASP™ Colistin (Liofilchem® srl), a compact panel containing the antibiotic in seven two-fold dilutions (0.25–16 mg/L), using frozen BMD plates (according to CLSI) as reference. Methods Colistin susceptibility testing was performed on a nationwide collection of 392 carbapenem-resistant K. pneumoniae isolates using BMD according to the CLSI and by ComASP™ Colistin according to the manufacturer’s recommendations. Susceptibility test results were interpreted according to EUCAST v.7.1 breakpoints (2017). Colistin was active in vitro against 251 K. pneumoniae isolates (64.0%) with an MIC range of 0.5 mg/L to >64 mg/L and MIC50/90 values of 1/64 mg/L. Essential and categorical agreements were calculated according to ISO20776-2. Results ComASP™ Colistin showed high levels of overall/evaluable essential agreement (94.9%/93.6%) and categorical agreement (97.2%), with very major errors in 0.7% (1/141 colistin-resistant), and met the current acceptance criteria proposed by the CLSI. Ten major errors were observed [4.0% (10/251) colistin-susceptible], three of which were within essential agreement. Conclusions ComASP™ Colistin is a commercial BMD method that reliably determined colistin MICs in a large collection of carbapenem-resistant K. pneumoniae isolates.

In December 2019, the Antibacterial Resistance Leadership Group (ARLG) was awarded funding for another 7-year cycle to support a clinical research network on antibacterial resistance. ARLG 2.0 has 3 overarching research priorities: infections caused by antibiotic-resistant (AR) gram-negative bacteria, infections caused by AR gram-positive bacteria, and diagnostic tests to optimize use of antibiotics. To support the next generation of AR researchers, the ARLG offers 3 mentoring opportunities: the ARLG Fellowship, Early Stage Investigator seed grants, and the Trialists in Training Program. The purpose of this article is to update the scientific community on the progress made in the original funding period and to encourage submission of clinical research that addresses 1 or more of the research priority areas of ARLG 2.0.

Rationale & Objective Staphylococcus aureus (S aureus) bacteremia (SAB) is associated with morbidity and mortality in patients receiving maintenance hemodialysis (HD). We evaluated changes in clinical and bacterial characteristics, and their associations with clinical outcomes with SAB in this population over a 21-year period. Study Design Prospective cohort study. Setting & Participants 453 hospitalized, non-neutropenic adults receiving maintenance HD who developed monomicrobial SAB between 1995 and 2015. Exposure Clinical characteristics and bacterial genotype. Outcome All-cause and SAB-attributable mortality, persistent bacteremia, and metastatic complications. Analytical Approach Proportions of participants experiencing each outcome were calculated overall and by calendar year. Secular trends were estimated using binomial risk regression, a generalized linear model with the log link function for a binomial outcome. Associations with outcomes were estimated using logistic regression. Results Over the 21-year study period, patients receiving maintenance HD experienced significant increases in age- and diabetes-adjusted SAB-attributable mortality (0.45% [95% CI, 0.36%-0.46%] per year), persistent bacteremia (0.86% [95% CI, 0.14%-1.55%] per year), metastatic complications (0.84% [95% CI, 0.11%-1.56%] per year), and infection with the virulent S aureus clone USA300 (1.47% [95% CI, 0.33%-2.52%] per year). Over time, the suspected source of SAB was less likely to be a central venous catheter (−1.32% [95% CI, −2.05 to −0.56%] per year) or arteriovenous graft (−1.08% [95% CI, −1.54 to −0.56] per year), and more likely to be a nonvascular access source (1.89% [95% CI, 1.29%-2.43%] per year). Patients with a nonvascular access suspected source of infection were more likely to die as a result of their S aureus infection (OR, 3.20 [95% CI, 1.36-7.55]). The increase in USA300 infections may have contributed to the observed increase in persistent bacteremia (OR, 2.96 [95% CI, 1.12-7.83]) but did not explain the observed increases in SAB-attributable mortality (OR, 0.83 [95% CI, 0.19-3.61]) or metastatic complications (OR, 1.34 [95% CI, 0.53-3.41]). Limitations Single-center, inpatient cohort. Conclusions The clinical and molecular epidemiology of SAB in patients receiving maintenance HD has changed over time, with an increase in SAB-attributable mortality and morbidity despite a decline in catheter-related infections.

From September to October 2019, seven patients colonised or infected with a ceftazidime-avibactam (CZA)-resistant Klebsiella pneumoniae carbapenemase (KPC)-2-producing K. pneumoniae were detected in two intensive care units of a Greek general hospital. The outbreak strain was sequence type (ST)147 and co-produced KPC-2 and the novel plasmid-borne Vietnamese extended-spectrum β-lactamase (VEB)-25 harbouring a K234R substitution associated with CZA resistance. Epidemiological investigations revealed that the resistance was probably acquired by horizontal transmission independently from previous CZA exposure.

Purpose. The aim of this study was to evaluate the in vitro activity of double-carbapenem combinations against OXA-48-producing Klebsiella pneumoniae clinical isolates. Methodology. Double combinations of ertapenem, meropenem and imipenem were evaluated for synergy and bactericidal activity using the time–kill methodology. All antibiotics were tested at 10 mg l−1 and at a sub-inhibitory concentration of 0.5× minimum inhibitory concentration (MIC) for isolates with a carbapenem MIC≤8 mg l−1. Synergy was defined as a ≥2log10 colony-forming units (c.f.u.) ml−1 decrease of viable colonies at 24 h compared to the most active carbapenem alone. Results. Ten distinct K. pneumoniae clinical isolates were tested. All carried bla OXA-48 and bla CTX-M-15, and exhibited an MIC range of 64–128, 4–32 and 1–32 mg l−1 for ertapenem, meropenem and imipenem, respectively. Out of 48 isolate-combinations, synergy was observed in 9 (18.8 %) and cidal activity was observed in 13 (27.1 %). In vitro synergistic activity was noted for 5 out of 29 (17.2 %) ertapenem-, 6 out of 29 (20.7 %) meropenem- and 7 out of 38 (18.4 %) imipenem-containing combinations. No combination exhibited antagonism. Bactericidal activity was observed in 7 (24.1 %) ertapenem-, 8 (27.6 %) meropenem- and 11 (28.9 %) imipenem-containing combinations. Among the sub-inhibitory concentration combinations, three (15 %) ertapenem-, four (20 %) meropenem- and three (15 %) imipenem-containing ones showed synergistic interaction. Conclusion. Dual combinations of carbapenems, including those containing sub-inhibitory concentrations of antibiotics, were synergistic against multidrug-resistant (MDR) and extensively drug-resistant (XDR) K. pneumoniae isolates harbouring bla OXA-48.

Simple Summary Recent advances in nanotechnology gave rise to trials with various types of metallic nanoparticles (NPs) to enhance the radiosensitization of cancer cells while reducing or maintaining the normal tissue complication probability during radiation therapy. This work reviews the physical and chemical mechanisms leading to the enhancement of ionizing radiation’s detrimental effects on cells and tissues, as well as the plethora of experimental procedures to study these effects of the so-called “NPs’ radiosensitization”. The paper presents the need to a better understanding of all the phases of actions before applying metallic-based NPs in clinical practice to improve the effect of IR therapy. More physical and biological experiments especially in vivo must be performed and simulation Monte Carlo or mathematical codes based on more accurate models for all phases must be developed. Abstract Many different tumor-targeted strategies are under development worldwide to limit the side effects and improve the effectiveness of cancer therapies. One promising method is to enhance the radiosensitization of the cancer cells while reducing or maintaining the normal tissue complication probability during radiation therapy using metallic nanoparticles (NPs). Radiotherapy with MV photons is more commonly available and applied in cancer clinics than high LET particle radiotherapy, so the addition of high-Z NPs has the potential to further increase the efficacy of photon radiotherapy in terms of NP radiosensitization. Generally, when using X-rays, mainly the inner electron shells are ionized, which creates cascades of both low and high energy Auger electrons. When using high LET particles, mainly the outer shells are ionized, which give electrons with lower energies than when using X-rays. The amount of the produced low energy electrons is higher when exposing NPs to heavy charged particles than when exposing them to X-rays. Since ions traverse the material along tracks, and therefore give rise to a much more inhomogeneous dose distributions than X-rays, there might be a need to introduce a higher number of NPs when using ions compared to when using X-rays to create enough primary and secondary electrons to get the desired dose escalations. This raises the questions of toxicity. This paper provides a review of the fundamental processes controlling the outcome of metallic NP-boosted photon beam and ion beam radiation therapy and presents some experimental procedures to study the biological effects of NPs’ radiosensitization. The overview shows the need for more systematic studies of the behavior of NPs when exposed to different kinds of ionizing radiation before applying metallic-based NPs in clinical practice to improve the effect of IR therapy.

Background. There is little information about the efficacy of active alternative drugs to carbapenems except beta-lactam/beta-lactamase inhibitors for the treatment of bloodstream infections (BSIs) due to extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E). The objective of this study was to assess the outcomes of patients with BSI due to ESBL-E who received empiric therapy with such drugs (other active drugs [OADs]) or carbapenems. Methods. A multinational retrospective cohort study of patients with BSI due to ESBL-E who received empiric treatment with OADs or carbapenems was performed. Cox regression including a propensity score for receiving OADs was performed to analyze 30-day all-cause mortality as main outcome. Clinical failure and length of stay were also analyzed. Results. Overall, 335 patients were included; 249 received empiric carbapenems and 86 OADs. The most frequent OADs were aminoglycosides (43 patients) and fluoroquinolones (20 patients). Empiric therapy with OADs was not associated with mortality (hazard ratio [HR], 0.75; 95% confidence interval [CI],.38-1.48) in the Cox regression analysis. Propensity score-matched pairs, subgroups, and sensitivity analyses did not show different trends; specifically, the adjusted HR for aminoglycosides was 1.05 (95% CI,.51-2.16). OADs were neither associated with 14-day clinical failure (adjusted odds ratio, 0.62; 95% CI,.29-1.36) nor length of hospital stay. Conclusions. We were unable to show that empiric treatment with OAD was associated with a worse outcome compared with carbapenems. This information allows more options to be considered for empiric therapy, at least for some patients, depending on local susceptibility patterns of ESBL-E.

Background The best available treatment against carbapenemase-producing Enterobacteriaceae (CPE) is unknown. The objective of this study was to investigate the effect of appropriate therapy and of appropriate combination therapy on mortality of patients with bloodstream infections (BSIs) due to CPE. Methods In this retrospective cohort study, we included patients with clinically significant monomicrobial BSIs due to CPE from the INCREMENT cohort, recruited from 26 tertiary hospitals in ten countries. Exclusion criteria were missing key data, death sooner than 24 h after the index date, therapy with an active antibiotic for at least 2 days when blood cultures were taken, and subsequent episodes in the same patient. We compared 30 day all-cause mortality between patients receiving appropriate (including an active drug against the blood isolate and started in the first 5 days after infection) or inappropriate therapy, and for patients receiving appropriate therapy, between those receiving active monotherapy (only one active drug) or combination therapy (more than one). We used a propensity score for receiving combination therapy and a validated mortality score (INCREMENT-CPE mortality score) to control for confounders in Cox regression analyses. We stratified analyses of combination therapy according to INCREMENT-CPE mortality score (0–7 [low mortality score] vs 8–15 [high mortality score]). INCREMENT is registered with ClinicalTrials.gov, number NCT01764490. Findings Between Jan 1, 2004, and Dec 31, 2013, 480 patients with BSIs due to CPE were enrolled in the INCREMENT cohort, of whom we included 437 (91%) in this study. 343 (78%) patients received appropriate therapy compared with 94 (22%) who received inappropriate therapy. The most frequent organism was Klebsiella pneumoniae (375 [86%] of 437; 291 [85%] of 343 patients receiving appropriate therapy vs 84 [89%] of 94 receiving inappropriate therapy) and the most frequent carbapenemase was K pneumoniae carbapenemase (329 [75%]; 253 [74%] vs 76 [81%]). Appropriate therapy was associated with lower mortality than was inappropriate therapy (132 [38·5%] of 343 patients died vs 57 [60·6%] of 94; absolute difference 22·1% [95% CI 11·0–33·3]; adjusted hazard ratio [HR] 0·45 [95% CI 0·33–0·62]; p

The incidence of Staphylococcus aureus bacteremia (SAB) is significantly higher in African American (AA) than in European-descended populations. We used admixture mapping (AM) to test the hypothesis that genomic variations with different frequencies in European and African ancestral genomes influence susceptibility to SAB in AAs. A total of 565 adult AAs (390 cases with SAB; 175 age-matched controls) were genotyped for AM analysis. A case-only admixture score and a mixed χ2(1df) score (MIX) to jointly evaluate both single-nucleotide polymorphism (SNP) and admixture association (P

ObjectivesWe evaluated the in vitro activity of ceftolozane/tazobactam and comparator agents against MDR non-MBL Pseudomonas aeruginosa isolates collected from nine Greek hospitals and we assessed the potential synergistic interaction between ceftolozane/tazobactam and amikacin.MethodsA total of 160 non-MBL P. aeruginosa isolates collected in 2016 were tested for susceptibility to ceftolozane/tazobactam and seven comparator agents including ceftazidime/avibactam. Time–kill assays were performed for synergy testing using ceftolozane/tazobactam 60 or 7.5 mg/L, corresponding to the peak and trough concentrations of a 1.5 g q8h dose, respectively, in combination with 69 mg/L amikacin, corresponding to the free peak plasma concentration. Synergy was defined as a ≥2 log10 cfu/mL reduction compared with the most active agent.ResultsOverall, ceftolozane/tazobactam inhibited 64.4% of the P. aeruginosa strains at ≤4 mg/L. Colistin was the most active agent (MIC50/90, 0.5/2 mg/L; 96.3% susceptible) followed by ceftazidime/avibactam (MIC50/90, 4/16 mg/L; 80.6% susceptible). GES-type enzymes were predominantly responsible for ceftolozane/tazobactam resistance; 81.6% of the non-producers were susceptible. MICs for the P. aeruginosa isolates selected for synergy testing were 2–32 mg/L ceftolozane/tazobactam and 2–128 mg/L amikacin. The combination of ceftolozane/tazobactam with amikacin was synergistic against 85.0% of all the isolates tested and against 75.0% of the GES producers. No antagonistic interactions were observed.ConclusionsCeftolozane/tazobactam demonstrated good in vitro activity against MDR/XDR P. aeruginosa clinical isolates, including strains with co-resistance to other antipseudomonal drugs. In combination with amikacin, a synergistic interaction at 24 h was observed against 85.0% of P. aeruginosa strains tested, including isolates with ceftolozane/tazobactam MICs of 32 mg/L or GES producers.

The publisher regrets that the article has been published online on 01 March 2019 with errors in Table 1. In the originally published Table 1, the percentage of Imipenem-relebactam susceptibility was incorrectly written as 8 0, while correct data is 98.0. Also, in Meropenem row, column MIC

Until recently, chemotherapy for metastatic melanoma had disappointing results. The identification of immune checkpoints such as CTLA-4 and PD-1/PD-L1 has led to the development of an array of monoclonal antibodies (Mabs). These immunologic approaches against tumoral cells come with a novel kind of side effects that the clinician needs to be familiarized with. Herein, we report for the first time a case of organizing pneumonia, based on imaging and cytological analyses of bronchoalveolar lavage, possibly associated with the use of pembrolizumab, an anti-PD-1 Mab recently approved for the treatment of metastatic melanoma.

[Scope] The aim of these guidelines is to provide recommendations for decolonizing regimens targeting multidrug-resistant Gram-negative bacteria (MDR-GNB) carriers in all settings., [Methods] These evidence-based guidelines were produced after a systematic review of published studies on decolonization interventions targeting the following MDR-GNB: third-generation cephalosporin-resistant Enterobacteriaceae (3GCephRE), carbapenem-resistant Enterobacteriaceae (CRE), aminoglycoside-resistant Enterobacteriaceae (AGRE), fluoroquinolone-resistant Enterobacteriaceae (FQRE), extremely drug-resistant Pseudomonas aeruginosa (XDRPA), carbapenem-resistant Acinetobacter baumannii (CRAB), cotrimoxazole-resistant Stenotrophomonas maltophilia (CRSM), colistin-resistant Gram-negative organisms (CoRGNB), and pan-drug-resistant Gram-negative organisms (PDRGNB). The recommendations are grouped by MDR-GNB species. Faecal microbiota transplantation has been discussed separately. Four types of outcomes were evaluated for each target MDR-GNB:(a) microbiological outcomes (carriage and eradication rates) at treatment end and at specific post-treatment time-points; (b) clinical outcomes (attributable and all-cause mortality and infection incidence) at the same time-points and length of hospital stay; (c) epidemiological outcomes (acquisition incidence, transmission and outbreaks); and (d) adverse events of decolonization (including resistance development). The level of evidence for and strength of each recommendation were defined according to the GRADE approach. Consensus of a multidisciplinary expert panel was reached through a nominal-group technique for the final list of recommendations., [Recommendations] The panel does not recommend routine decolonization of 3GCephRE and CRE carriers. Evidence is currently insufficient to provide recommendations for or against any intervention in patients colonized with AGRE, CoRGNB, CRAB, CRSM, FQRE, PDRGNB and XDRPA. On the basis of the limited evidence of increased risk of CRE infections in immunocompromised carriers, the panel suggests designing high-quality prospective clinical studies to assess the risk of CRE infections in immunocompromised patients. These trials should include monitoring of development of resistance to decolonizing agents during treatment using stool cultures and antimicrobial susceptibility results according to the EUCAST clinical breakpoints., JTC and JRB are supported by ‘Plan Nacional de I+D+i 2013-2016’ and ‘Instituto de Salud Carlos III, Subdirección General de Redes y Centros de Investigación Cooperativa, Ministerio de Economía, Industria y Competitividad, Spanish Network for Research in Infectious Diseases (REIPI RD16/0016/0001; RD16/0016/0008)’, co-financed by the European Development Regional Fund ‘A way to achieve Europe’, Operative Programme Intelligent Growth 2014-2020.

Purpose There are few data in the literature regarding sepsis or septic shock due to extended-spectrum β-lactamases (ESBL)-producing Enterobacteriaceae (E). The aim of this study was to assess predictors of outcome in septic patients with bloodstream infection (BSI) caused by ESBL-E. Methods Patients with severe sepsis or septic shock and BSI due to ESBL-E were selected from the INCREMENT database. The primary endpoint of the study was the evaluation of predictors of outcome after 30 days from development of severe sepsis or septic shock due to ESBL-E infection. Three cohorts were created for analysis: global, empirical-therapy and targeted-therapy cohorts. Results 367 septic patients were analysed. Overall mortality was 43.9% at 30 days. Escherichia coli (62.4%) and Klebsiella pneumoniae (27.2%) were the most frequent isolates. β-lactam/β-lactamase inhibitor (BLBLI) combinations were the most empirically used drug (43.6%), followed by carbapenems (29.4%). Empirical therapy was active in vitro in 249 (67.8%) patients, and escalation of antibiotic therapy was reported in 287 (78.2%) patients. Cox regression analysis showed that age, Charlson Comorbidity Index, McCabe classification, Pitt bacteremia score, abdominal source of infection and escalation of antibiotic therapy were independently associated with 30-day mortality. No differences in survival were reported in patients treated with BLBLI combinations or carbapenems in empirical or definitive therapy. Conclusions BSI due to ESBL-E in patients who developed severe sepsis or septic shock was associated with high 30-day mortality. Comorbidities, severity scores, source of infection and antibiotic therapy escalation were important determinants of unfavorable outcome.

Background and aim A multicentre nationwide surveillance study was conducted in Greek hospitals to evaluate epidemiology of carbapenemase-producing Klebsiella pneumoniae clinical isolates, and their susceptibilities to last-line antibiotics. Methods: Minimum inhibitory concentrations (MICs) were evaluated by Etest, colistin MICs were also evaluated by broth microdilution SensiTest (now known as ComASP) Colistin. Carbapenemase genes were detected by PCR. Clonal relatedness was assessed by PFGE. Isolates were prospectively collected between November 2014 and April 2016, from 15 hospitals. Results: Among 394 isolates, K. pneumoniae carbepenemase (KPC) remained the most prevalent carbapenemase (66.5%). NDM was the second most prevalent (13.7%), identified in 12 hospitals, followed by VIM (8.6%). OXA-48- and double carbapenemase-producers remained rare (3.6%, 6.3%, respectively). Carbapenemase-producing K. pneumoniae isolates showed high resistance to last-line antibiotics. Gentamicin and colistin were the most active in vitro with 61.9% and 59.6% of the isolates to be inhibited at ≤ 2mg/L, followed by fosfomycin (susceptibility (S): 58.4%) and tigecycline (S: 51.5%). Ceftazidime/avibactam inhibited 99.6% of KPC and 100% of OXA-48-like-producing isolates, while temocillin was active against 58% of KPC isolates at urinary breakpoint of ≤ 32mg/L* and only 2.7% at systemic breakpoint of ≤ 8mg/L. NDM-producing isolates belonged mainly to one clone, whereas KPC, VIM, OXA-48 and double carbapenemase-producers were mainly polyclonal. Conclusions: KPC remains the predominant carbapenemase among K. pneumoniae in Greece, followed by NDM, whereas changing trends of resistance rates to last-line antimicrobials against carbapenemase-producing K. pneumoniae with the exception of ceftazidime/avibactam mandates continuing surveillance to support clinical practice.

The spread of extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) is leading to increased carbapenem consumption. Alternatives to carbapenems need to be investigated. We investigated whether β-lactam/β-lactamase inhibitor (BLBLI) combinations are as effective as carbapenems in the treatment of bloodstream infections (BSI) due to ESBL-E. A multinational, retrospective cohort study was performed. Patients with monomicrobial BSI due to ESBL-E were studied; specific criteria were applied for inclusion of patients in the empirical-therapy (ET) cohort (ETC; 365 patients), targeted-therapy (TT) cohort (TTC; 601 patients), and global cohort (GC; 627 patients). The main outcome variables were cure/improvement rate at day 14 and all-cause 30-day mortality. Multivariate analysis, propensity scores (PS), and sensitivity analyses were used to control for confounding. The cure/improvement rates with BLBLIs and carbapenems were 80.0% and 78.9% in the ETC and 90.2% and 85.5% in the TTC, respectively. The 30-day mortality rates were 17.6% and 20% in the ETC and 9.8% and 13.9% in the TTC, respectively. The adjusted odds ratio (OR) (95% confidence interval [CI]) values for cure/improvement rate with ET with BLBLIs were 1.37 (0.69 to 2.76); for TT, they were 1.61 (0.58 to 4.86). Regarding 30-day mortality, the adjusted OR (95% CI) values were 0.55 (0.25 to 1.18) for ET and 0.59 (0.19 to 1.71) for TT. The results were consistent in all subgroups studied, in a stratified analysis according to quartiles of PS, in PS-matched cases, and in the GC. BLBLIs, if active in vitro, appear to be as effective as carbapenems for ET and TT of BSI due to ESLB-E regardless of the source and specific species. These data may help to avoid the overuse of carbapenems. (This study has been registered at ClinicalTrials.gov under registration no. NCT01764490.), The work was funded by the Ministerio de Economía y Competitividad, Instituto de Salud Carlos III, cofinanced by European Development Regional Fund titled A Way To Achieve Europe ERDF, the Spanish Network for Research in Infectious Diseases (REIPI RD12/0015), and FIS (PI10/02021). Participants in the study received support for research from the Innovative Medicines Initiative Joint Undertaking under the Combatting Bacterial Resistance in Europe—Molecule against Gram Negative Infections (COMBACTE-MAGNET) agreement 115737 resources, which are composed of financial contributions from the European Union's Seventh Framework Programme (FP7/2007-2013) and the European Federation of Pharmaceutical Industries and Associations (EFPIA) companies' in kind contributions (A. Pascua and J. Rodríguez-Baño), the Cleveland Department of Veterans Affairs, the Veterans Affairs Merit Review Program, the Geriatric Research Education and Clinical Center VISN 10 (VISN 10 GRECC), and NIAID, NIH, under award numbers R01AI072219 and R01AI063517 (R. A. Bonomo).

Background The species-specific risk of cardiac device-related infection (CDRI) among bacteremic patients is incompletely understood. Methods We conducted a prospective cohort study of hospitalized patients from October 2002 to December 2014 with a cardiac device (CD) and either Staphylococcus aureus bacteremia (SAB) or Gram-negative bacteremia (GNB). Cardiac devices were defined as either prosthetic heart valves (PHVs), including valvular support rings, permanent pacemakers (PPMs)/automatic implantable cardioverter defibrillators (AICDs), or left ventricular assist devices (LVADs). Results During the study period, a total of 284 patients with ≥1 CD developed either SAB (n = 152 patients) or GNB (n = 132 patients). Among the 284 patients, 150 (52.8%) had PPMs/AICDs, 72 (25.4%) had PHVs, 4 (1.4%) had LVADs, and 58 (20.4%) had >1 device present. Overall, 54.6% of patients with SAB and 16.7% of patients with GNB met criteria for definite CDRI (P < .0001). Multivariable logistic regression analysis revealed that 3 bacterial species were associated with an increased risk for CDRI: Staphylococcus aureus (odds ratio [OR] = 5.57; 95% confidence interval [CI], 2.16–14.36), Pseudomonas aeruginosa (OR = 50.28; 95% CI, 4.16–606.93), and Serratia marcescens (OR = 7.75; 95% CI, 1.48–40.48). Conclusions Risk of CDRI among patients with bacteremia varies by species. Cardiac device-related infection risk is highest in patients with bacteremia due to S aureus, P aeruginosa, or S marcescens. By contrast, it is lower in patients with bacteremia due to other species of Gram-negative bacilli. Patients with a CD who develop bacteremia due to either P aeruginosa or S marcescens should be considered for diagnostic imaging to evaluate for the presence of CDRI.

Carbapenemase-producing Enterobacteriaceae (CPE) have spread worldwide, causing serious infections with increasing frequency. CPE are resistant to almost all available antibiotics, complicating therapy and limiting treatment options. Mortality rates associated with CPE infections are unacceptably high, indicating that the current therapeutic approaches are inadequate and must be revised. Here, we review 20 clinical studies (including those describing the largest cohorts of CPE-infected patients) that provided the necessary information regarding isolate and patient characteristics and treatment schemes, as well as a clear assessment of outcome. The data summarized here indicate that treatment with a single in vitro active agent resulted in mortality rates not significantly different from that observed in patients treated with no active therapy, whereas combination therapy with two or more in vitro active agents was superior to monotherapy, providing a clear survival benefit (mortality rate, 27.4% vs. 38.7%; p

Purpose. The aim of the study was to investigate the prevalence of plasmid-mediated quinolone resistance (PMQR) genes in an unselected collection of bloodstream isolates recovered over an 18-month period in a laboratory affiliated to a university hospital in Athens, Greece, and to assess their impact on the in vitro activity of ciprofloxacin and levofloxacin. Methods. Eight PMQR genes were screened by PCR and sequencing. All PMQR-positive isolates were submitted to isoelectric focusing for β-lactamase detection, conjugation or transformation, time-kill assays, mutant prevention concentrationand inoculum effect evaluation. PCR and sequencing of gyrA and parC were performed for detection of chromosomal mutations. Results. Among 96 Gram-negative isolates, 7 (7.3 %) carried one or more PMQR genes. qnrS1 was the most prevalent (5.2 %), followed by aac(6′ )-Ib-cr (4.2 %) and their combination (2 %). Cloning was successful for three isolates. The presence of a single PMQR determinant without any target modification was not associated with quinolone resistance with one exception, S tenotrophomonas maltophilia carrying qnrS1, which was resistant to norfloxacin and ciprofloxacin, but in this isolate, additional mechanisms of quinolone resistance cannot be excluded. All PMQR-positive isolates showed a significant inoculum effect. The mutant prevention concentrations of ciprofloxacin against the quinolone-susceptible clinical isolates ranged from 0.38 to 32 mg l−1 and those of levofloxacin from 1 to 32 mg l−1. Conclusions. PMQRs compromised the bactericidal activity of ciprofloxacin and levofloxacin when expressed in Enterobacter cloacae, S. maltophilia or Klebsiella pneumoniae and when more than one co-existed. PMQR determinants represent an unrecognized threat, capable to compromise the in vitro activity of quinolones if expressed in a favourable genetic environment and to favour selection of resistant mutants by widening the mutant selection window of these agents.

Objectives We characterized the first ceftazidime-avibactam-resistant KPC-producing-Klebsiella pneumoniae clinical isolate detected in Greece, before the introduction of ceftazidime-avibactam in clinical practice. Methods K. pneumoniae KP-90 was isolated from a hospitalized patient in Thessaloniki during a nationwide surveillance study conducted between 2014 and 2016. Antimicrobial susceptibility was tested against a panel of agents. Whole-genome sequencing (Ion Torrent TM platform) of the isolate was carried out to identify the acquired resistance genes and mutations that were associated with ceftazidime-avibactam resistance. Results The K. pneumoniae isolate belonged to multilocus sequence type ST258 and harboured blaKPC-23 as the only carbapenemase gene. The isolate had a minimum inhibitory concentration (MIC) of 16 mg/L to ceftazidime-avibactam and was highly resistant to imipenem, meropenem (MICs, 512 mg/L) and ceftazidime (MIC, >1024 mg/L). blaKPC-23 was detected on a Tn4401a transposon, located on a pKPQIL-type plasmid. A non-functional outer membrane protein OmpK35 and an OmpK36 variant that had been previously associated with K. pneumoniae isolates of ST258 were detected. Transformation studies with Escherichia coli TOP10 showed that KPC-23 offered similar carbapenem MICs as KPC-2 and KPC-3. However, KPC-23 conferred a four-fold higher ceftazidime MIC (>1024 mg/L), which in the presence of avibactam was reduced (>7-fold) to 8 mg/L, which is just within the limit of the susceptibility breakpoint. Conclusions Ceftazidime-avibactam resistance in a KPC-23- producing K. pneumoniae clinical isolate was due to increased ceftazidime hydrolysis and was likely enhanced by OmpK35 porin deficiency.

The antimicrobial activity of copper surfaces against a variety of contemporary carbapenemase-producing Gram-negative bacteria representative of the most problematic nosocomial pathogens worldwide was evaluated.Twenty-four clinical isolates, comprising four of Escherichia coli, two of Enterobacter spp., eight of Klebsiella pneumoniae and five each of Pseudomonas aeruginosa and Acinetobacter baumannii producing either VIM-1 and/or KPC-2 or VIM-2 or OXA-type carbapenemases, were studied. The antimicrobial activity of 99% copper (Cu99%) and a 63% alloy (Cu63%) was evaluated in comparison with that of stainless steel (SS) and polyvinylchloride (PVC) by incubating ∼10(6) cfu/cm(2) of the tested strains on each surface at room temperature.Copper demonstrated antimicrobial activity against all studied isolates. This effect was observed earlier and was more pronounced for Cu99% than for Cu63%. Cu99% showed a bactericidal effect after2 h for A. baumannii, 3 h for Enterobacter spp., 5 h for K. pneumoniae and 6 h for P. aeruginosa and E. coli. No viable colonies were recovered from five (20.8%) isolates after 3 h and from nine (37.5%) isolates after 5 h of incubation on Cu99%.Copper has significant antimicrobial activity against multidrug-resistant nosocomial Gram-negative pathogens. This supports the hypothesis that replacement of high-contact materials with copper could reduce the high burden of environmental contamination around high-risk patients. However, this strategy should be seen as an adjunctive measure to established cleaning protocols and to good hygiene practices for prevention of hospital-acquired infections.

The in vitro activity of plazomicin was evaluated against 300 multidrug resistant (MDR) (carbapenemase and/or ESBL-producing) isolates from four hospitals in Athens, an area where carbapenemase-producing organisms are endemic. Most of the isolates were also resistant to the legacy aminoglycosides with the MIC50/MIC90 to tobramycin, amikacin and gentamicin being 32/>32, 32/>32 and 4/>8 μg/ml, respectively. ACHN-490 retained activity (MICs⩽4 μg/ml) against all isolates of Klebsiella pneumoniae, Escherichia coli, and Enterobacter spp. tested with MIC50 and MIC90 of 1 and 2 μg/ml, respectively, irrespective of their MDR phenotype and it represents a promising alternative for the treatment of the most problematic Gram-negative pathogens.

BACKGROUND Although metallo-β-lactamases (MBLs) hydrolyse most β-lactams, including carbapenems, MBL-producing Enterobacteriaceae very often remain susceptible to carbapenems in vitro. We studied the in vivo efficacy of imipenem, meropenem, ertapenem and aztreonam against a carbapenem-susceptible MBL-producing clinical Escherichia coli strain in a rabbit intra-abdominal abscess model. METHODS Rabbits were inoculated intraperitoneally with 10(8) cfu/mL of VIM-1-positive E. coli and were assigned to receive no treatment (controls) or intravenous imipenem/cilastatin (imipenem) 70 mg/kg/12 h or meropenem 125 mg/kg/12 h or ertapenem 60 mg/kg/12 h or aztreonam 70 mg/kg/12 h. Dosing regimens were chosen on the basis of preliminary pharmacokinetic studies so that T(>MIC) was achieved for ≥50% of the dosing interval for all tested antibiotics. A total of eight doses were administered before sacrifice and the abscesses were harvested and quantitatively cultured. RESULTS MICs of imipenem, meropenem, ertapenem and aztreonam for the infecting isolate were 1, ≤0.25, 1.5 and ≤0.25 mg/L, respectively. The log(10) cfu/g (mean ± SD) viable counts in pus were as follows: controls (n = 16), 8.71 ± 1.34 (P

Background Recurrent Staphylococcus aureus bacteremia (Re-SAB) occurs in 2–17% of patients with SAB within 3–12 months after resolution of the first episode. The risk factors for Re-SAB are incompletely understood. Methods Re-SAB was defined as a second episode of SAB after the resolution of the first episode occurring at least 14 days from the date of the last positive blood culture of the first episode. Using the SAB Group Prospective Cohort Study (SABG-PCS) data between January 2008 and May 2015, patients with Re-SAB were selected and compared with those without it. Pulsed-field gel electrophoresis (PFGE) was done for the clinical isolates from the Re-SAB group, and spa typing was for those from both groups. Baseline sera from patients with Re-SAB and age/race/gender matched (1:1) control subjects with SAB but without Recurrence underwent Luminex multiplex cytokine array. Results Seventy patients experienced Re-SAB (9.3%) and 686 SAB patients did not. In the Re-SAB group, 156 episodes of SAB were observed. Median time to Re-SAB was 147.5d (IQR, 76–358). Among 65 PFGE-analyzed pairs of isolates from the first and the subsequent episodes, the time to Re-SAB of Conclusion Re-SAB involves a combination of multiple factors of host, microbe, and treatment. Further laboratory investigation for any determinants in host and microbe is required. Disclosures V. G. Fowler Jr., Merck, Cerexa/Actavis, Pfizer, Advanced Liquid Logis, NIH, MedImmune, Basilea, Karius, Contrafect, Regneron, Genentech, Affinergy, Locus, Medical Surface, Inc., Achaogen, Astellas, Arsanis, Bayer, Cubist, Debiopharm, Durata, Grifols, Medicines Co, Novartis: Collaborator, Consultant and Scientific Advisor, Consulting fee, Research grant and Research support.

The susceptibility of 25 Stenotrophomonas maltophilia (S. maltophilia) clinical isolates to four different antimicrobials (trimethoprim/sulfomethoxazole, piperacillin/tazobactam, ceftazidime, ciprofloxacin) were investigated by disk diffusion, E-test and commercial Sensititre and PASCO broth microdilution techniques. Discrepancies between the results of broth microdilution and the other methods studied were characterized as very major, major and minor errors. Using the broth microdilution as the reference method, 24% of the isolates were found susceptible to trimethoprim/ sulfamethoxazole, 24% to ceftazidime, 0% to piperacillin/tazobactam and 12% to ciprofloxacin. Good correlation was observed between the two broth microdilution Sensititre and PASCO for all antibiotics tested. Disc diffusion and E-test generated inconsistent results for all agents except trimethoprim/sulfamethoxazole. A great genomic diversity was demonstrated within the S. maltophilia strains tested. Although our results confirm that trimethoprim-sulfamethoxazole had some in vitro activity against S. maltophilia, further clinical studies are necessary to evaluate the clinical efficacy of these compounds for the treatment of S. maltophilia infections, since no randomized controlled trials have been carried out and no correlation between the clinical response and susceptibility testing results has been reported. Furthermore, the high genomic diversity observed in the S. maltophilia strains indicates the need for careful epidemiological evaluation especially in nosocomial outbreaks.

Linezolid (trade names Zyvox™ , Zyvoxid™ and Zyvoxam™) is a synthetic antimicrobial agent of the family of oxazolidinones, which has been approved for the treatment of vancomycin-resistant Enterococcus faecium infections, lower respiratory tract infections, skin and skin-structure infections and diabetic foot infections caused by susceptible bacteria. Its antimicrobial spectrum, which includes Gram-positive cocci and bacteria resistant to other antimicrobials, its favorable pharmacokinetic properties and its safety profile make it an important addition to our therapeutic armamentarium. In this review, we summarize the literature describing linezolid’s in vitro characteristics, the clinical experience regarding its approved and off-label clinical uses and its safety and tolerability.

Received 17 November 2007; returned 28 November 2007; revised 5 December 2007; accepted 11 December 2007 Objectives: Clinical isolates of Klebsiella pneumoniae (91), Escherichia coli (49), Enterobacter spp. (27), Proteus mirabilis (17), Citrobacter freundii (2), Providencia stuartii (3) and Serratia spp. (5), with various MICs of imipenem, were examined for production of metallo-b-lactamases (MBLs) with different phenotypic laboratory tests that have been previously published to detect MBLs in Pseudomonas aeruginosa and Acinetobacter spp. Methods: A total of 194 (95 MBL-positive and 99 MBL-negative) clinical isolates with imipenem MICs � 0.25 to >256 mg/L were examined. All isolates were evaluated by the double-disc synergy test (DDST), the combination disc test (CDT), the MBL Etest and the modified Hodge test. The presence of blaVIM and blaIMP genes was evaluated by in situ hybridization with specific probes and was certified by PCR. Results :I n 30blaVIM-positive isolates that exhibited MICs of imipenem � 4 mg/L, MBL Etest could not be evaluated. CDT with ceftazidime and 1900 or 750 mg of EDTA, and DDST after applying an imipenem disc 10 mm apart from a disc containing 1900 mg of EDTA, showed the highest sensitivity (97.9% to 100%) and specificity (87.9% to 96%) rates among the analysed procedures. CDT with imipenem and 1900 mg of EDTA exhibited a sensitivity of 94.7% and showed very good specificity (98%). Conclusions: The CDT with imipenem/imipenem10.5 M EDTA or ceftazidime/ceftazidime10.2 M EDTA and the DDST with imipenem 10 mm apart from EDTA are the most effective methods for the detection of MBLs in Enterobacteriaceae.

Vancomycin-resistant enterococci (VRE) have emerged as significant nosocomial pathogens. A hospital-wide prevalence study was performed to identify cases with VRE faecal colonisation. A case-control study using two randomly selected VRE-negative controls for each positive case was performed to assess risk-factors for VRE colonisation by univariate and multivariate analysis. VRE faecal colonisation was documented in 53 (14.3%) of 370 patients screened. Previous exposure to anti-anaerobic agents, as well as quinolones, was associated with VRE colonisation (p

Objectives: Infections due to multidrug-resistant (MDR) Gram-negative pathogens in the ICU have prompted the use of colistin, an antibiotic forgotten for decades. The aim of this retrospective observational study was to record and present the emergence of colistin-resistant Klebsiella pneumoniae (CRKB) in a Greek ICU. Methods: In a new university tertiary hospital, the first patients admitted in the ICU were already colonized or infected with MDR pathogens, and this led to frequent colistin use as part of empirical or microbiologically documented therapy. Colistin resistance was defined as MIC >4 mg/L by the Etest method. All CRKB isolated in surveillance cultures or clinical specimens in the ICU during the period 2004-5 were recorded along with patients' characteristics. Results: Eighteen CRKB were isolated from 13 patients over a 16 month period, representing either colonizing or infective isolates. Patients' mean age was 70 years, with a mean APACHE II score at admission of 22. They all had a long hospitalization (median 69 days) and a long administration of colistin (median 27 days). Colistin-resistant isolates were implicated as pathogens in two bacteraemias, a ventilator-associated pneumonia and two soft tissue infections. Repetitive extragenic palindromic PCR identified six distinct clones, and horizontal transmission was also documented. Conclusions: Selective pressure due to extensive or inadequate colistin use may lead to the emergence of colistin resistance among K. pneumoniae isolates, jeopardizing treatment options in the ICU, potentially increasing morbidity and mortality of critically ill patients and necessitating prudent use of colistin.

Nasopharyngeal Streptococcus pneumoniae isolates colonising young children are representative of isolates causing clinical disease. This study determined the frequency of macrolide-non-susceptible pneumococci, as well as their phenotypic and genotypic characteristics, among pneumococci collected during two cross-sectional surveillance studies of the nasopharynx of 2847 children attending day-care centres in the Athens metropolitan area during 2000 and 2003. In total, 227 macrolide-non-susceptible pneumococcal isolates were studied. Increases in macrolide non-susceptibility, from 23% to 30.3% (p

A clinical isolate of Enterobacter cloacae exhibiting reduced susceptibility to imipenem and a positive EDTA-disc synergy test was studied for carbapenemase production.MICs were determined with standard procedures as well as using a higher inoculum. Isoelectric focusing of cell extracts was used for detection of beta-lactamases. PCR assays with primers specific for the bla(VIM) gene and the conserved segments of class 1 integrons and sequence analyses were carried out to identify the gene and to map the metallo-beta-lactamase encoding integron. Transferability of the gene was assessed with conjugation experiments using the filter mating technique. To identify the location of the bla(VIM-1) gene, Southern hybridization was carried out in genomic DNA using an internal fragment of the bla(VIM-1) gene as a probe, amplified by PCR.The isolate was resistant to extended-spectrum beta-lactams. The MICs of carbapenems were below the resistance breakpoints but rose above resistance breakpoints when an inoculum of 10(8) cfu/mL was used. Isoelectric focusing detected a beta-lactamase with a pI of 6.1, which exhibited imipenem-hydrolysing activity in a microbiological assay. Ceftazidime and imipenem resistance were not transferable by conjugation. PCR assays identified the bla(VIM-1) gene in the variable region of a class 1 integron which also carried the aac(6')-IIc gene. The bla(VIM-1) probe hybridized with an approximately 130 kb fragment of genomic DNA, suggesting a chromosomal location of the gene.We describe a novel class 1 integron containing bla(VIM-1) and aac(6')-IIc genes in an E. cloacae clinical isolate.

Using time-kill methodology, we investigated the interactions of fosfomycin with meropenem or colistin or gentamicin against 17 genetically distinct Klebsiella pneumoniae clinical isolates carrying bla KPC-2 . Synergy was observed with meropenem or colistin against 64.7 and 11.8% of tested isolates, while the combination with gentamicin resulted in indifference. All studied combinations showed improved bactericidal activity, compared to fosfomycin alone and prevented the development of fosfomycin resistance in 69.2, 53.8, and 81.8% of susceptible isolates, respectively.

Background Antibiotic resistance, a major public health problem, has been linked to antibiotic consumption. In Greece both consumption and resistance rates are among the highest in Europe. A multifaceted campaign targeting both physicians and parents of school children was implemented for the first time in order to educate the public and update doctors, aiming to promote judicious use of antibiotics and hopefully decrease its consumption. Methods The programme consisted of a public education campaign and academic detailing of primary care physicians in the district of Corinth in Peloponnese. The experience and perceptions of parents were recorded in the meetings in the form of course evaluation and assessment, anonymous questionnaires. The use of Rapid Antigen Detection Test (RADT) for streptococcal pharyngitis by primary care physicians was also assessed by use of anonymous questionnaires. Antibiotic consumption was compared before and after the programme between the district of Corinth and the other districts of Peloponnese, as well as at a national level. Results Antibiotic consumption remained unaltered at 26 Defined daily doses per 1000 Inhabitants per Day (DID) in accordance with the trend in other regions and at a national level. However, the utilization of Amoxycillin and Penicillin was increased by 34.3%, while the use of other antimicrobial classes including macrolides, cephalosporins and fluoroquinolones decreased by 6.4-21.9%. The use of RADT did not lead to a significantly decreased antimicrobial consumption. Conclusions A multifaceted educational programme targeting both the general public and primary care physicians was associated with rationalization in the choice of antimicrobial. A reduction in the total antimicrobial consumption was not achieved. Electronic supplementary material The online version of this article (doi:10.1186/1471-2458-14-866) contains supplementary material, which is available to authorized users.

We describe three cases of community-acquired necrotizing pneumonia which were caused by Panton-Valentine leucocidin-producing strains of Staphylococcus aureus (one of them methicillin sensitive). All cases were successfully treated without any sequelae for the patients due to the prompt initiation of adequate antimicrobial therapy. High suspicion toward this fatal pathogen was the key to the successful outcome of the patients.

Η εξωκυττάρια βλεννοπολυσακχαριδική ουσία (slime), που παράγεται από πολλά στελέχη κοαγκουλάοη-αρνητικών σταφυλόκοκκων, έχει αναγνωρισθεί τα τελευταία χρόνια ως σημαντικός λοιμογόνος παράγοντας, υπεύθυνος για την πρόκληση δυσίατων λοιμώξεων από τα μικρόβια αυτά σε ασθενείς που φέρουν ξένα σώματα. Η ουσία αυτή ενοχοποιείται για την συχνή αποτυχία της συντηρητικής αγωγής στη θεραπεία αυτού του είδους των λοιμώξεων. Στην παρούσα διδακτορική διατριβή μελετήθηκε η μεταβολή της δραστικότητας όλων των αντιβιοτικών με αντισταφυλοκοκκικό φάσμα από την παρουσία της βλεννοπολυσακχαρίδης. Για το σκοπό αυτό εφαρμόσθηκαν δύο διαφορετικές in vitro ημιποσοτικές μέθοδοι. Στην πρώτη χρησιμοποιήθηκαν 26 κλινικά και 2 πρότυπα στελέχη κοαγκουλάοη-αρνητικών σταφυλόκοκκων που παρήγαγαν βλεννοπολυσακχαρίδη (σύμφωνα με τη μέθοδο του Christensen) και 14 κλινικά και 2 πρότυπα στελέχη που δεν παρήγαγαν την ουσία αυτή. Σαράντα μΙ καλλιεργήματος σε Tryptic Soy Broth από κάθε μικρόβιο ενοφθαλμίσθηκαν στην επιφάνεια στείρων φίλτρων κυτταρίνης που είχαν τοποθετηθεί σε τρυβλία με Staphylococcus άγαρ No 110. Μετά από 24ωρη επώαση τα φίλτρα ξεπλύθηκαν σε 3 διαδοχικά δοχεία με Tryptic Soy Broth και τοποθετήθηκαν σε τρυβλία με Mueller Hinton άγαρ που είχε αναμειχθεί με σπόρους Bacillus subtilis. Στην επιφάνεια κάθε φίλτρου τοποθετήθηκε διάλυμα του υπό εξέταση αντιβιοτικού (40μΙ) και μετά από 24ωρη επώαση μετρήθηκαν οι ζώνες αναστολής στο άγαρ και συγκρίθηκαν με τον αντίστοιχο μάρτυρα, δηλαδή τη ζώνη αναστολής που δημιουργήθηκε από τη διέλευση ίσης ποσότητας αντιβιοτικού μέσω στείρου φίλτρου. Διαπιστώθηκε ότι η τεϊκοπλανίνη και η βανκομυκίνη, όταν διηθούνται μέσω φίλτρου που έχει προεπωασθεί με στέλεχος σταφυλόκοκκου που παράγει βλεννοπολυσακχαρίδη, παρουσιάζουν μείωση δραστικότητας κατά 29,6 και 73,5%, αντίστοιχα ενώ όλα τα υπόλοιπα αντιβιοτικά παρουσιάζουν μείωση δραστικότητας από 2,5 ως 11,8%. Όταν τα αντιβιοτικά διηθούνται μέσω φίλτρου που έχει προεπωασθεί με στέλεχος που δεν παράγει βλεννοπολυσακχαρίδη διαπιστώνεται ότι μείωση δραστικότητας παρουσιάζουν μόνο η ριφαμπικίνη, η κοτριμοξαζόλη, η σιπροφλοξασίνη, η πεφλοξασίνη, η γενταμικίνη, η ερυθρομυκίνη, η τομπραμυκίνη, η αμικασίνη, και η τεϊκοπλανίνη από 0,3 ως 3,6%. Στη δεύτερη μέθοδο, που περιγράφεται για πρώτη φορά στη βιβλιογραφία, χρησιμοποιήθηκαν τα 26 κλινικά και τα 2 πρότυπα στελέχη κοαγκουλάοη-αρνητικών σταφυλόκοκκων που παρήγαγαν βλεννοπολυσακχαρίδη. Στείρα φίλτρα κυτταρίνης, που είχαν τοποθετηθεί σε τρυβλία με Staphylococcus άγαρ No 110, ενοφθαλμίσθηκαν με 40 μΙ καλλιεργήματος κάθε στελέχους και επωάσθηκαν αεροβίως για 24 ώρες. Μετά από ξέπλυμα σε 3 διαδοχικά δοχεία με Tryptic Soy Broth, από την επιφάνεια κάθε φίλτρου συλλέχθηκε η βλεννοπολυσακχαρίδη και αναμείχθηκε με 40 μΙ διαλύματος του υπό εξέταση αντιβιοτικού. Το μείγμα αυτό τοποθετήθηκε σε οπές που είχαν διανοιχθεί σε τρυβλία με Mueller Hinton άγαρ, στο οποίο είχε ενσωματωθεί εναιώρημα Bacillus subtilis. Μετά από 24ωρη επώαση μετρήθηκαν οι ζώνες αναστολής και συγκρίθηκαν με τον μάρτυρα, δηλαδή τη ζώνη αναστολής που δημιουργήθηκε από ίση ποσότητα αντιβιοτικού χωρίς βλεννοπολυσακχαρίδη. Από τη σύγκριση προκύπτει ότι η πεφλοξασίνη, η τεϊκοπλανίνη και η βανκομυκίνη παρουσιάζουν αξιοσημείωτη μεταβολή της δραστικότητας τους από την παρουσία της εξωκυττάριας βλεννοπολυσακχαρίδης κατά 30, 51,7 και 66,8%, αντίστοιχα. Αντίθετα, η ριφαμπικίνη, η κλινδαμυκίνη και οι μακρολίδες παρουσιάζουν τη μικρότερη μείωση στη δραστικότητα τους (0,8-2,3%). Η παρουσία της βλεννοπολυσακχαρίδης μειώνει τη δραστικότητα των υπολοίπων αντιβιοτικών από 4 ως 16,1%. Τα αποτελέσματα της παρούσας μελέτης θα βοηθήσουν τον κλινικό ιατρό στην ορθολογική επιλογή των δραστικότερων αντιβιοτικών για τη θεραπεία των λοιμώξεων των ξένων σωμάτων από στελέχη κοαγκουλάση-αρνητικών σταφυλόκοκκων, που παράγουν εξωκυττάρια βλεννοπολυσακχαρίδη.