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Antibiotics are often used in neonates despite the absence of relevant dosing information in drug labels. For neonatal dosing, clinicians must extrapolate data from studies for adults and older children, who have strikingly different physiologies. As a result, dosing extrapolation can lead to increased toxicity or efficacy failures in neonates. Driven by these differences and recent legislation mandating the study of drugs in children and neonates, an increasing number of pharmacokinetic studies of antibiotics are being performed in neonates. These studies have led to new dosing recommendations with particular consideration for neonate body size and maturation. Herein, we highlight the available pharmacokinetic data for commonly used systemic antibiotics in neonates.

This retrospective cohort study included 53 patients admitted to the intensive care unit (ICU), with an average age of 69 years, without neurologic disorder before initiation of a continuous piperacillin infusion at the standard dose and who underwent piperacillin serum concentration monitoring. Among them, 23 developed a neurologic disorder for which the piperacillin causality was chronologically and semiologically suggestive. A concentration threshold of 157.2 mg/liter independently predicted neurotoxicity with 96.7% specificity and 52.2% sensitivity and may constitute a limitation when targeting less susceptible pathogens., (Copyright © 2017 American Society for Microbiology.)

Background: Extended piperacillin-tazobactam (TZP) infusions have been associated with favourable outcomes. There are currently no pediatric dosing recommendations., Objectives: To determine appropriate TZP dosing strategies in children 2 months - 6 years according to age and different minimal inhibitory concentrations (MICs)., Methods: Age and weight were simulated for 1000 children. Post-hoc pharmacokinetic parameter estimates were generated using published clearance and volume of distribution data. For different dosing regimens, we estimated the probability of target attainment (PTA) over a range of MICs from 4 to 128 mg/L. The pharmacodynamic (PD) target was defined as free piperacillin concentrations above the MIC for ≥ 50% of the dosing interval. A PTA ≥ 90% was defined as optimal., Results: PTA decreased as MIC and age increased. In all age groups, standard dosing regimens (240-300 mg/kg/day, 0.5h infusions) failed to reach PTAs ≥ 90% at MICs ≥ 16 mg/L. Standard 0.5h infusions reached PTAs ≥ 90% at MICs up to 8 mg/L in infants > 2 to 6m. No 0.5h infusion reached PTAs ≥ 90% for MICs ≥ 4 mg/L in children > 6m. While none of the tested regimens were optimal at MICs > 16 mg/L in children > 6m, 100 mg/kg/dose every 6h as a 3h infusion reached PD target at MICs of 32 mg/L in infants > 2 to 6m., Conclusions: Up to MICs of 16 mg/L, 90 mg/kg/dose every 8h as a 2h infusion in infants > 2 to 6m and 100 mg/kg/dose every 8h as a 4h infusion in children > 6m-6y achieved PTAs ≥ 90%., (© 2017 Journal of Population Therapeutics and Clinical Pharmacology. All rights reserved.)

Objective: To evaluate the reliability of using imipenem, meropenem, cefoperazone-sulbactam, piperacillin-tazobactam in the treatment of hospital-acquired Gram-negative bacterial infections with Monte Carlo simulation(MCS). Methods: The MIC of the four agents collected from hospital-acquired infections were detected in accordance with broth dilution method of Clinical and Laboratory Standard Institute (CLSI). MCS were conducted with MICs and the pharmacokinetics parameters of the four agents based on conventional dose regimens.The cumulative fraction of response (CFR) of time over MIC target attainment in different dosing regimen were generated. Results: A total of 2 541 strains, including 2 093 strains of Enterobacteriaceae and 448 strains of glucose non - fermentative bacilli were collected.The MIC(90) of imipenem and meropenem against Enterobacteriaceae were less than 1 mg/L in general, whereas MIC(90) of two agents with β-lactamase inhibitors was around 64 mg/L.As to glucose non - fermenting bacteria, MICs of all the four agents were very high, especially to Acinetobacter baumannii, which indicated MIC(50) more than 32 mg/L.MCS revealed that carbapenems had significantly higher CFR than those with β-lactamase inhibitors.Imipenem and meropenem (1 g, q8 h) obtained CFRs of 74.69% and 81.42%, respectively.The CFR of cefoperazone-sulbactam (2 g, q8 h) and piperacillin-tazobactam (4 g, q6 h) (both excluding β-lactamase inhibitors) were just 49.59% and 27.66% respectively, which increased after excluding A . baumannii in piperacillin-tazobactam. Conclusions: The conventional dose regimens of imipenem and meropenem are reliable for the empiric therapy of Gram-negative hospital-acquired bacterial infections.Piperacillin-tazobactam is suggested to use with higher doses or prolonged infusion time to satisfy the time of drug concentration exceeded the MIC(T>MIC)requirement.More clinical studies of cefoperazone-sulbactam should be conducted to optimize its regimen and guarantee its efficacy.

This prospective pharmacokinetic study aimed to compare the clearance of piperacillin-tazobactam administered as a 24-h continuous infusion between continuous venovenous haemodiafiltration (CVVHDF) and continuous venovenous haemofiltration (CVVH) applied at equal dose in critically ill patients. A loading dose of 4.5 g of piperacillin-tazobactam followed by a continuous infusion (500 mg/h) was administered to patients randomized to receive CVVHDF or CVVH. Serial pre- and postfilter blood samples were drawn during an 8-h sampling interval. Piperacillin plasma concentrations were measured using a validated chromatography method. Piperacillin pharmacokinetics were calculated using a non-compartmental approach. In total, 212 piperacillin plasma concentrations were determined. Median [interquartile range (IQR)] total piperacillin clearance was 7.5 (5.9-11.2) L/h in the CVVHDF group and 4.7 (4.5-9.6) L/h in the CVVH group (P = 0.21). Median (IQR) piperacillin clearance related to continuous renal replacement therapy (CRRT) was 3.0 (2.7-3.2) L/h in the CVVHDF group and 2.6 (1.9-3.0) L/h in the CVVH group (P = 0.29). Mean (standard deviation) steady state concentrations were 68.4 (25.8) mg/L in the CVVHDF group and 89.1 (35.6) mg/L in the CVVH group (P = 0.16). The estimated unbound concentrations resulting from piperacillin continuous infusion were above the target susceptibility breakpoint (16 mg/L) for the entire dosing interval (100% fT >MIC ) in all study patients. In the present study, higher (but not significantly) piperacillin clearance and lower piperacillin exposure were observed in patients receiving CVVHDF compared with CVVH. In patients receiving CRRT, the use of piperacillin continuous infusion should be considered to ensure optimal exposure for less susceptible pathogens., (Copyright © 2017. Published by Elsevier B.V.)

A 31-year-old woman with systemic lupus erythematosus presented to the emergency department with cough for 1 week. Chest radiograph demonstrated cavitating lesion in the right upper zone with surrounding ground-glass change. Blood culture results from the day of hospital presentation grew Pseudomonas aeruginosa Sputum sample and pleural fluid grew P. aeruginosa and were negative for acid-fast bacilli. P. aeruginosa is a rare cause of cavitating lung lesion and has been associated with immunocompromised hosts. Most reports of cavitating P. aeruginosa lesions have been identified in patients who are immunocompromised secondary to HIV.The current case highlights the potential for infection in patients who are immunosuppressed therapeutically and appropriate investigations are necessary to rule out common causes of cavitating lung lesions., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Optimal dosing of β-lactam antibiotics in critically ill patients is a challenge given the unpredictable pharmacokinetic profile of this patient population. Several studies have shown intermittent dosing to often yield inadequate drug concentrations. Continuous dosing is an attractive alternative from a pharmacodynamic point of view. This study evaluated whether, during continuous dosing, piperacillin concentrations reached and maintained a pre-defined target in critically ill patients. Adult patients treated with piperacillin by continuous dosing in the intensive care unit of a university medical centre in The Netherlands were prospectively studied. Total and unbound piperacillin concentrations drawn at fixed time points throughout the entire treatment course were determined by liquid chromatography-tandem mass spectrometry. A pharmacokinetic combined target of a piperacillin concentration ≥80 mg/L, reached within 1 h of starting study treatment and maintained throughout the treatment course, was set. Eighteen patients were analysed. The median duration of monitored piperacillin treatment was 60 h (interquartile range, 33-96 h). Of the 18 patients, 5 (27.8%) reached the combined target; 15 (83.3%) reached and maintained a less strict target of >16 mg/L. In this patient cohort, this dosing schedule was insufficient to reach the pre-defined target. Depending on which target is to be met, a larger initial cumulative dose is desirable, combined with therapeutic drug monitoring., (Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Objectives: To characterize the population pharmacokinetics of piperacillin and tazobactam in critically ill infants and children, in order to develop an evidence-based dosing regimen., Patients and Methods: This pharmacokinetic study enrolled patients admitted to the paediatric ICU for whom intravenous piperacillin/tazobactam (8:1 ratio) was indicated (75 mg/kg every 6 h based on piperacillin). Piperacillin/tazobactam concentrations were measured by an LC-MS/MS method. Pharmacokinetic data were analysed using non-linear mixed effects modelling., Results: Piperacillin and tazobactam blood samples were collected from 47 patients (median age 2.83 years; range 2 months to 15 years). Piperacillin and tazobactam disposition was best described by a two-compartment model that included allometric scaling and a maturation function to account for the effect of growth and age. Mean clearance estimates for piperacillin and tazobactam were 4.00 and 3.01 L/h for a child of 14 kg. Monte Carlo simulations showed that an intermittent infusion of 75 mg/kg (based on piperacillin) every 4 h over 2 h, 100 mg/kg every 4 h given over 1 h or a loading dose of 75 mg/kg followed by a continuous infusion of 300 mg/kg/24 h were the minimal requirements to achieve the therapeutic targets for piperacillin (60% f T >MIC >16 mg/L)., Conclusions: Standard intermittent dosing regimens do not ensure optimal piperacillin/tazobactam exposure in critically ill patients, thereby risking treatment failure. The use of a loading dose followed by a continuous infusion is recommended for treatment of severe infections in children >2 months of age., (© The Author 2017. 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.)

Appropriate antibiotic dosing is critical to improve outcomes in critically ill patients with sepsis. The addition of continuous renal replacement therapy makes achieving appropriate antibiotic dosing more difficult. The lack of continuous renal replacement therapy standardization results in treatment variability between patients and may influence whether appropriate antibiotic exposure is achieved. The aim of this study was to determine if continuous renal replacement therapy effluent flow rate impacts attaining appropriate antibiotic concentrations when conventional continuous renal replacement therapy antibiotic doses were used. This study used Monte Carlo simulations to evaluate the effect of effluent flow rate variance on pharmacodynamic target attainment for cefepime, ceftazidime, levofloxacin, meropenem, piperacillin, and tazobactam. Published demographic and pharmacokinetic parameters for each antibiotic were used to develop a pharmacokinetic model. Monte Carlo simulations of 5000 patients were evaluated for each antibiotic dosing regimen at the extremes of Kidney Disease: Improving Global Outcomes guidelines recommended effluent flow rates (20 and 35 mL/kg/h). The probability of target attainment was calculated using antibiotic-specific pharmacodynamic targets assessed over the first 72 hours of therapy. Most conventional published antibiotic dosing recommendations, except for levofloxacin, reach acceptable probability of target attainment rates when effluent rates of 20 or 35 mL/kg/h are used., (Copyright © 2017 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.)

An appropriate antibiotherapy is crucial for the safety and recovery of patients. Depending on the clinical conditions of patients, the required dose to effectively eradicate an infection may vary. An inadequate dosing not only reduces the efficacy of the antibiotic, but also promotes the emergence of antimicrobial resistances. Therefore, a personalized therapy is of great interest for improved patients' outcome and will reduce in long-term the prevalence of multidrug-resistances. In this context, on-site monitoring of the antibiotic blood concentration is fundamental to facilitate an individual adjustment of the antibiotherapy. Herein, we present a bioinspired approach for the bedside monitoring of free accessible ß-lactam antibiotics, including penicillins (piperacillin) and cephalosporins (cefuroxime and cefazolin) in untreated plasma samples. The introduced system combines a disposable microfluidic chip with a naturally occurring penicillin-binding protein, resulting in a high-performance platform, capable of gauging very low antibiotic concentrations (less than 6 ng ml -1 ) from only 1 µl of serum. The system's applicability to a personalized antibiotherapy was successfully demonstrated by monitoring the pharmacokinetics of patients, treated with ß-lactam antibiotics, undergoing surgery.

To determine the pharmacokinetics of piperacillin/tazobactam in Hispaniolan Amazon parrots ( Amazona ventralis ), 8 healthy adult parrots of both sexes were used in a 2-part study. In a pilot study, piperacillin (87 mg/kg) in combination with tazobactam (11 mg/kg) was administered intramuscularly (IM) to 2 birds, and blood samples were obtained at 0, 0.5, 1, 1.5, 2, 3, 4, 6, 8, and 10 hours after administration. Based on the results obtained, a main study was done in which piperacillin/tazobactam was administered at 2 different doses. In 3 birds, the initial dose of piperacillin (87 mg/kg)/tazobactam (11 mg/kg) IM was administered, and in 3 birds, the dose was doubled to piperacillin (174 mg/kg)/tazobactam (22 mg/kg) IM. In all 6 birds, blood samples were obtained at 0, 5, 15, and 30 minutes and at 1, 1.5, 2, 2.5, 3, and 4 hours after administration. Quantification of plasma piperacillin and tazobactam concentrations was determined by validated liquid chromatography-mass spectrometry assay. Pharmacokinetic parameters were determined by noncompartmental analysis. After intramuscular administration, the mean ± standard error values of T 1/2 (h) was 0.52 ± 0.05 and 0.32 ± 0.07, T max (h) was 0.28 ± 0.09 and 0.25 ± 0.10, C max (μg/mL) was 86.34 ± 20.62 and 9.03 ± 2.88, and C max /dose was 0.99 ± 0.24 and 0.83 ± 0.26 for piperacillin (87 mg/kg) and tazobactam (11 mg/kg), respectively. When the doses were doubled, the T 1/2 (h) was 0.65 ± 0.08 and 0.34 ± 0.02, T max (h) was 0.28 ± 0.12 and 0.14 ± 0.06, C max (μg/mL) was 233.0 ± 6.08 and 22.13 ± 2.35, and C max /dose was 1.34 ± 0.03 and 1.02 ± 0.11 for piperacillin and tazobactam, respectively. Results indicate that piperacillin is rapidly absorbed and reaches high initial concentrations; however, it is also rapidly eliminated in the Hispaniolan Amazon parrot, and tazobactam has similar pharmacokinetics as piperacillin. Administration of piperacillin at 87 mg/kg IM q3-4h is recommended for this species to control infections attributed to susceptible bacteria with a minimum inhibitory concentration of ≤4 μg/mL.

Covalent modification of protein by drugs may disrupt self-tolerance, leading to lymphocyte activation. Until now, determination of the threshold required for this process has not been possible. Therefore, we performed quantitative mass spectrometric analyses to define the epitopes formed in tolerant and hypersensitive patients taking the β-lactam antibiotic piperacillin and the threshold required for T cell activation. A hydrolyzed piperacillin hapten was detected on four lysine residues of human serum albumin (HSA) isolated from tolerant patients. The level of modified Lys 541 ranged from 2.6 to 4.8%. Analysis of plasma from hypersensitive patients revealed the same pattern and levels of modification 1-10 d after the commencement of therapy. Piperacillin-responsive skin-homing CD4 + clones expressing an array of Vβ receptors were activated in a dose-, time-, and processing-dependent manner; analysis of incubation medium revealed that 2.6% of Lys 541 in HSA was modified when T cells were activated. Piperacillin-HSA conjugates that had levels and epitopes identical to those detected in patients were shown to selectively stimulate additional CD4 + clones, which expressed a more restricted Vβ repertoire. To conclude, the levels of piperacillin-HSA modification that activated T cells are equivalent to the ones formed in hypersensitive and tolerant patients, which indicates that threshold levels of drug Ag are formed in all patients. Thus, the propensity to develop hypersensitivity is dependent on other factors, such as the presence of T cells within an individual's repertoire that can be activated with the β-lactam hapten and/or an imbalance in immune regulation., (Copyright © 2017 by The American Association of Immunologists, Inc.)

Background: This randomized prospective study was designed to assess whether piperacillin/tazobactam (PIPC/TAZ) is as effective as meropenem (MEPM) as a first-line antibiotic treatment for febrile neutropenia (FN)., Procedure: FN episodes were randomly assigned to receive either PIPC/TAZ (337.5 mg/kg per day in three doses, 1-hr DIV, maximum 13.5 g per day) or MEPM (120 mg/kg per day in three doses, 1-hr DIV, maximum 3 g per day). Clinical responses were evaluated 120 hr after the DIV., Results: A total of 434 febrile episodes in 105 patients (42 females and 63 males) with a median age of 8 years (range 0-25) were included in this trial. Blood cultures were positive in 47 out of the 434 episodes (10.8%). Regarding responses to the treatment, success rates between the PIPC/TAZ and MEPM groups were similar (62.4 vs. 65.9%, P = 0.484), even if patients were restricted to those with bacteremia (26.1 vs 37.5%, P = 0.534). Mortality rates did not significantly differ between the two groups (0.8 vs. 0%, P = 0.500)., Conclusion: Both PIPC/TAZ and MEPM appeared to be equally efficacious and safe. Carbapenems are now broadly used to treat FN; however, this may increase the prevalence of drug-resistant bacteria. In this regard, the treatment using PIPC/TAZ for FN is more beneficial., (© 2016 Wiley Periodicals, Inc.)

Aim: Implementing a mouse model of Acinetobacter baumannii (AB) digestive colonization and studying the propensity of an intestinal reservoir of AB to be at the origin of pneumonia., Materials & Methods: After a disruption of the digestive flora by piperacillin-tazobactam, two multidrug-resistant AB strains were intranasally inoculated to two cohorts of ten mice daily. For each strain, five mice were rendered transiently neutropenic., Results & Conclusion: One strain persisted several weeks in the digestive tract, even after stopping piperacillin-tazobactam injections, leading to the hypothesis that some AB strains can authentically colonize the gut. Most of the immunocompromised mice experienced clinical signs and positive lung cultures, which were associated with positive spleen cultures, an argument in favor of bacterial translocation.

Study Objective: Increased acute kidney injury (AKI) incidence has been reported in patients receiving piperacillin-tazobactam (PTZ) therapy compared with other β-lactams. The authors sought to determine if the addition of β-lactamase inhibitors impacts AKI incidence by comparing patients treated with PTZ or ampicillin-sulbactam (SAM)., Design: Retrospective cohort study., Setting: Large academic tertiary care hospital., Patients: Overall, 2448 patients received PTZ (n=1836) or SAM (n=612) for at least 48 hours between September 1, 2007, and September 30, 2015. Patients were excluded for pregnancy, cystic fibrosis, chronic kidney disease, and initial creatinine clearance < 30 ml/min. Patients were matched on Charlson Comorbidity Index, initial creatinine clearance, hypotension exposure, various nephrotoxic drug exposures, history of diabetes, heart failure, and hypertension., Measurements and Main Results: AKI occurred in 265 patients at similar rates for both groups (PTZ 11.4% vs SAM 9.2%; p=0.14). After stratifying by vancomycin exposure and controlling for confounders, there was no difference in the risk of AKI for SAM or PTZ (adjusted odds ratio [aOR] 0.87, 95% confidence interval [CI] 0.59-1.25). The addition of vancomycin (VAN) to PTZ increased the likelihood of AKI compared with PTZ alone (aOR 1.77, 95% CI 1.26-2.46). Concomitant SAM and VAN therapy was not associated with a significant increase in AKI compared with SAM monotherapy (aOR 1.01, 95% CI 0.48-1.97)., Conclusion: Rates of AKI were similar for PTZ and SAM in a matched cohort. The addition of a β-lactamase inhibitor is not likely the mechanism in the observed increased rates of AKI in patients treated with vancomycin and PTZ., (© 2017 Pharmacotherapy Publications, Inc.)

Objective: Obesity and critical illness modify pharmacokinetics of antibiotics, but piperacillin-tazobactam continuous IV infusion pharmacokinetics has been poorly studied in obese critically ill patients. We aimed to compare pharmacokinetics of piperacillin in severely obese and nonobese patients with severe sepsis or septic shock. We hypothesized that plasma concentration variability would expose the critically ill to both piperacillin under and overdosing., Methods: Prospective comparative study. Consecutive critically ill severely obese (body mass index, > 35 kg/m) and nonobese patients (body mass index, < 30 kg/m) were treated with 16 g/2 g/24 hr continuous piperacillin-tazobactam infusion. Piperacillin plasma concentration was measured every 12 hours over a 7-day period by high-pressure liquid chromatography. Unbound piperacillin plasma concentration and fractional time of plasma concentration spent over 64 mg/L (4-fold the minimal inhibitory concentration for Pseudomonas aeruginosa) were compared between the two groups. We performed 5,000 Monte Carlo simulations for various dosing regimens and minimal inhibitory concentration and calculated the probability to spend 100% of the time over 64 mg/L., Results: We enrolled 11 severely obese and 12 nonobese patients and obtained 294 blood samples. We did not observe a statistically significant difference in piperacillin plasma concentrations over time between groups. The fractional time over 64 mg/L was 64% (43-82%) and 93% (85-100%) in obese and nonobese patients, respectively, p = 0.027 with intra- and intergroup variability. Five nonobese and two obese patients experienced potentially toxic piperacillin plasma concentrations. When 64 mg/L was targeted, Monte Carlo simulations showed that 12 g/1.5 g/24 hr was inadequate in both groups and 16 g/2 g/24 hr was adequate only in nonobese patients., Conclusion: Using a conventional dosing of 16 g/2 g/24 hr continuous infusion, obese patients were more likely than nonobese patients to experience piperacillin underdosing when facing high minimal inhibitory concentration pathogens. The present study suggests that piperacillin drug monitoring might be necessary in the sickest patients who are at the highest risk of unpredictable plasma concentration exposing them to overdose, toxicity, underdosing, and treatment failure.

We implemented an antimicrobial stewardship (AS) program whereby pharmacists sought appropriate use of antimicrobial agents in January 2012. At that time, we targeted anti-methicillin-resistant Staphylococcus aureus (MRSA) agents and carbapenems; however, in January 2014, we added tazobactam/piperacillin (TAZ/PIPC). We evaluated outcomes using multilateral analyses. The average one-day dosage of carbapenems increased; however, the duration of administration and number of recipient patients decreased significantly (P < 0.01). Moreover, the percentage of patients receiving meropenem (MEPM), for whom the time above minimal inhibitory concentration (MIC) was 40% or higher increased (P < 0.01). In contrast, patient utilization of TAZ/PIPC increased significantly after targeting of carbapenems as specific antibacterial agents. However, after TAZ/PIPC was targeted as a specific antibacterial agent, the number of TAZ/PIPC administrations decreased significantly (P < 0.01). The duration of hospitalization and mortality rate in patients receiving specific antibacterial agents significantly decreased after implementation of the AS program (P < 0.01). In conclusion, pharmacist's interventions to provide AS and patient follow-up reduced improper use and promoted proper administration of antibacterial agents. Furthermore, AS was effective in improving patient prognoses and suppressing drug-resistant strains, as well as promoting effective treatment.

Purpose: To prospectively evaluate the observed incidence of acute kidney injury (AKI) in adult patients receiving the combination of piperacillin-tazobactam and vancomycin versus the combination of cefepime or meropenem and vancomycin for greater than 72 hours., Methods: This was a prospective, open-label cohort study at a community academic medical center involving adult patients over a 3-month time period who received either the combination of piperacillin-tazobactam and vancomycin or the combination of cefepime or meropenem and vancomycin for greater than 72 hours. The patients were evaluated for AKI, defined using specific criteria introduced by Kidney Disease: Improving global outcomes (KDIGO) acute kidney injury work group in 2012., Results: A total of 85 patients receiving either antimicrobial combination were evaluated for AKI. The incidence of AKI was significantly higher in the piperacillin-tazobactam and vancomycin group (37.3%) compared with the cefepime or meropenem and vancomycin group (7.7%; χ 2 = 7.80, P = .005)., Conclusion: The result of this study suggests that the risk of developing AKI is increased in patients receiving the combination of piperacillin-tazobactam and vancomycin versus those receiving the combination of cefepime or meropenem and vancomycin.

Objectives: To determine if time to initial antimicrobial is associated with progression of severe sepsis to septic shock., Design: Retrospective cohort., Setting: Six hundred fifty-six bed urban academic medical center., Patients: Emergency department patients greater than or equal to 18 years old with severe sepsis and/or septic shock and antimicrobial administration within 24 hours. Patients with shock on presentation were excluded., Interventions: Not available., Measurements and Main Results: We identified 3,929 severe sepsis patients, with overall mortality 12.8%. Nine hundred eighty-four patients (25.0%) progressed to septic shock. The median time to antimicrobial was 3.77 hours (interquartile range = 1.96-6.42) in those who progressed versus 2.76 hours (interquartile range = 1.60-4.82) in those who did not (p < 0.001). Multivariate logistic regression demonstrated that male sex (odds ratio = 1.18; 95% CI, 1.01-1.36), Charlson Comorbidity Index (odds ratio = 1.18; 95% CI, 1.11-1.27), number of infections (odds ratio = 1.05; 95% CI, 1.02-1.08), and time to first antimicrobial (odds ratio = 1.08; 95% CI, 1.06-1.10) were associated with progression. Each hour until initial antimicrobial administration was associated with a 8.0% increase in progression to septic shock. Additionally, time to broad-spectrum antimicrobial was associated with progression (odds ratio = 1.06; 95% CI, 1.05-1.08). Time to initial antimicrobial was also associated with in-hospital mortality (odds ratio = 1.05; 95% CI, 1.03-1.07)., Conclusions: This study emphasizes the importance of early, broad-spectrum antimicrobial administration in severe sepsis patients admitted through the emergency department, as longer time to initial antimicrobial administration is associated with increased progression of severe sepsis to septic shock and increased mortality.

The Clinical and Laboratory Standards Institute (CLSI) recently re-examined Pseudomonas aeruginosa minimum inhibitory concentration (MIC) susceptibility breakpoints for piperacillin/tazobactam (TZP). The objectives of this study were to analyse the impact of elevated TZP MICs (32-64 mg/L) versus lower respective MICs on P. aeruginosa bacteraemia patient outcomes. Data were gathered from a Veterans Health Administration national clinical database on P. aeruginosa bacteraemia episodes from 2007 to 2013. Patients treated with TZP were identified, comprising 53 elevated MIC episodes and 301 low MIC episodes. Propensity score matching (1:2 ratio) utilising independent variables associated with 30-day all-cause mortality was conducted to compare the outcomes of 53 elevated MIC episodes with 106 matched low MIC episodes. Independent baseline variables associated with 30-day all-cause mortality for all 354 episodes were hyperkalaemia, elevated blood urea nitrogen, elevated temperature, hypoglycaemia, lack of urinary source and thrombocytopenia. Similar 30-day all-cause mortality was found between the two propensity-matched TZP groups (elevated MIC 24.5% vs. low MIC 22.6%; P = 0.79)., (Published by Elsevier B.V.)

The purpose of this study was to assess the pharmacokinetic (PK) characteristics, clinical efficiency, and pharmacoeconomic parameters of piperacillin/tazobactam administered by extended infusion (EI) or intermittent infusion (II) in the treatment of hospital-acquired pneumonia (HAP) in critically ill patients with low illness severity in China. Fifty patients completed the study, with 25 patients receiving 4/0.5 g piperacillin/tazobactam over 30 min as the II group and 25 patients receiving 4/0.5 g piperacillin/tazobactam over 3 h every 6 h as the EI group. Drug assay was performed using high-performance liquid chromatography (HPLC). The percentage of the dosing interval for which the free piperacillin concentration (%fT) exceeds the minimum inhibitory concentration (MIC) was calculated. The patients' therapy cost, clinical efficiency, and adverse effects were also recorded. %fT>MIC was about 100, 98.73, and 93.04 % in the EI arm versus 81.48, 53.29, and 42.15 % in the II arm, respectively, when the microorganism responsible for HAP had an MIC of 4, 8, and 16 mg/L. The therapy cost in the EI group was lower than that of the II group ($1351.72 ± 120.39 vs. $1782.04 ± 164.51, p = 0.001). However, the clinical success rate, clinical failure rate, and drug-related adverse events did not significantly differ between groups. EI treatment with piperacillin/tazobactam was a cost-effective approach to the management of HAP, being equally clinically effective to conventional II., Competing Interests: Compliance with ethical standards All procedures performed in this study involving human participants were in accordance with the ethical standards of Tianjin Medical University Cancer Institute and Hospital. The study was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all individual participants included in the study. This article does not contain any studies with animals performed by any of the authors. Conflict of interest All of the authors declare that they have no conflict of interest.

Study Objective: Despite recent reports of relatively high rates (16-37%) of acute kidney injury (AKI) in patients receiving the combination of intravenous piperacillin-tazobactam (PTZ) and vancomycin, data are limited evaluating the impact of PTZ infusion strategy on the occurrence of nephrotoxicity. The objective of this study was to compare the rates of nephrotoxicity in patients receiving vancomycin in combination with PTZ administered as an extended infusion (EI) versus a standard infusion (SI)., Design: Single-center, retrospective, matched-cohort study., Setting: Large academic tertiary care hospital., Patients: Two hundred eighty adults with a creatinine clearance (CrCl) of 40 ml/minute or higher who received at least 96 hours of vancomycin plus PTZ EI (140 patients) or vancomycin plus PTZ SI (140 patients) between January 1, 2009, and December 31, 2011, and between January 1, 2013, and December 31, 2014 (year 2012 was skipped due the closure of inpatient units following Superstorm Sandy); 48 patients in each group were admitted to the intensive care unit., Measurements and Main Results: The median age of all patients was 67 (interquartile range [IQR] 54-77) years, and CrCl was 75 (IQR 55-107) ml/minute. Nephrotoxicity was assessed by the risk, injury, failure, loss, and end-stage kidney disease (RIFLE) and Acute Kidney Injury Network (AKIN) criteria. Rates of AKI, according to these criteria, were similar between groups: 17.9% versus 17.1% (p=1) and 32.9% versus 29.3% (p=0.596) for the PTZ EI and PTZ SI groups, respectively. When controlling for residual differences between groups in a conditional logistic regression analysis, no association was observed between receipt of PTZ EI and RIFLE-defined AKI (odds ratio 0.522, 95% confidence interval 0.043-6.295, p=0.609). Time to onset of nephrotoxicity was 4 (IQR 3-6) days, with no significant difference noted between groups (p=0.887)., Conclusion: Our findings suggest a similar rate of nephrotoxicity between patients who received vancomycin in combination with PTZ EI versus PTZ SI. These results need to be further validated in a prospective randomized controlled study., (© 2017 Pharmacotherapy Publications, Inc.)

Background: This study was conducted to observe the clinical efficacy of long-term piperacillin-tazobactam (TZP) infusion and identify the factors affecting its curative effect against pneumonia in patients who had undergone surgery for abdominal tumor., Methods: The 100 patients were divided into four clinical groups according to the severity of their infection: Simple pneumonia, pneumonia with pleural effusion, pneumonia and atelectasis, and severe pneumonia. Each group of patients was then divided into control and treatment groups using a completely random design. The control group received TZP as a regular infusion, and the treatment group received TZP as a long-term infusion. The cure time in the different groups was compared according to the administration regimen, and stratified analysis was carried out to identify the efficacy factors of long-term TZP infusion for patients with each kind of pneumonia., Results: The average cure time for TZP differed significantly among the groups. In particular, the average cure times in the simple pneumonia, pneumonia with pleural effusion, pneumonia and atelectasis, and severe pneumonia groups were 6.800 ± 0.342, 7.320 ± 0.304, 10.840 ± 0.571, and 15.942 ± 0.973 d (p < 0.001). In each group, the usage time of antibiotics in the treatment groups was significantly shorter than in the control group (8.87 ± 0.64 vs. 15.95 ± 2.02 d; p < 0.001). The cure times (d) for simple pneumonia and pneumonia and atelectasis were conspicuously lower in the treatment groups than in the control group (5.667 ± 0.256 vs. 7.846 ± 0.451; p < 0.001; 9.667 ± 1.432 vs. 11.923 ± 0.947; p = 0.024). The factors associated with continuous treatment effectiveness were being male, age <70 years, Acute Physiology and Chronic Health Evaluation score ≥17 points, minimum inhibitory concentration of the pathogen 8 mcg/mL, oxygenation index >200 mm Hg, serum procalcitonin concentration >4 ng/mL, and serum albumin <25 g/L., Conclusion: Long-term TZP infusion exhibited better clinical efficacy than did traditional treatment in patients with pneumonia after abdominal tumor surgery.

Recent studies have shown that the pharmacodynamic (PD) index driving the efficacy of β-lactam/β-lactamase inhibitor combinations such as ceftazidime/avibactam and ceftolozane/tazobactam is the percentage of time the free inhibitor concentration is above a threshold (fT >threshold ). However, data with piperacillin/tazobactam (TZP) are scarce. Here we aimed to assess the relationship between fT >threshold and TZP antibacterial efficacy by a population pharmacokinetic study in mice and dose-effect experiments in a neutropenic murine thigh infection model with two isogenic strains of Escherichia coli differentially expressing TEM-1 β-lactamase. We also explored the dynamics of resistance selection with the innovator and a non-equivalent generic, extrapolated the results to the clinic by Monte Carlo simulation of standard TZP doses, and estimated the economic impact of generic-selected resistance. The fT >threshold index described well the efficacy of TZP versus E. coli, with threshold values from 0.5 mg/L to 2 mg/L and mean exposures of 42% for stasis and 56% for 1 log 10 kill. The non-equivalent generic required a longer exposure (fT >threshold 33%) to suppress resistance compared with the innovator (fT >threshold 22%), leading to a higher frequency of resistance selection in the clinical simulation (16% of patients with the generic vs. 1% with the innovator). Finally, we estimated that use of TZP generics in a scenario of 25% therapeutic non-equivalence would result in extra expenses approaching US$1 billion per year in the USA owing to selection of resistant micro-organisms, greatly offsetting the savings gained from generic substitution and further emphasising the need for demonstrated and not assumed therapeutic equivalence., (Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Background: Observational studies have suggested an increased risk of nephrotoxicity when piperacillin-tazobactam is added to vancomycin, although the data are confliciting., Objective: To perform a meta-analysis of identified studies to assess if adding piperacillin-tazobactam to vancomycin increases the incidence of nephrotoxicity., Method: A systematic review of PubMed, EMBASE, Cochrane Central, and Google Scholar was conducted to identify studies. Studies selected for meta-analysis were full length reports, retrospective or prospective, and designed specifically to assess if the combining piperacillin-tazobactam with vancomycin increases nephrotoxicity., Results: Six observational trials involving 963 patients were identified and analyzed. Five trials were retrospective and one was prospective. Vancomycin/piperacillin-tazobactam was compared to vancomycin alone in 2 trials, to vancomycin/cefepime in 3 trials, and vancomycin/cefepime or meropenem in one. Meta-analysis showed a statistical increase in the incidence of nephrotoxicity when piperacillin-tazobactam/vancomycin is compared to the control group (2.26 95% CI 1.41-3.63, p= 0.0007). No differences were noted between groups in patients requiring renal replacement., Conclusion: Adding piperacillin-tazobactam to vancomycin increases the risk of nephrotoxicity when compared to vancomycin alone or vancomycin with either cefepime or meropenem., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.)

Study Objective: To determine whether critically ill patients receiving extended-infusion (EI) piperacillin/tazobactam would have improved clinical outcomes compared with patients receiving intermittent infusions., Design: Single-center, open-label, prospective study., Setting: Twenty-two-bed intensive care unit (ICU) in a regional hospital in Hong Kong., Patients: A total of 367 adults who had a diagnosis of either bacterial infection or neutropenic fever and had received treatment with piperacillin/tazobactam for at least 48 hours between December 1, 2013, and August 31, 2015., Intervention: Patients were assigned to receive piperacillin/tazobactam as either a 4-hour EI (182 patients [EI group]) or a 30-minute intermittent infusion (185 patients [non-extended infusion (NEI) group])., Measurements and Main Results: All patients were followed for at least 14 days after treatment assignment. The primary outcome was the 14-day mortality rate after initiation of piperacillin/tazobactam. Secondary outcomes included in-hospital mortality rate, time to defervescence, duration of mechanical ventilatory support, length of ICU stay, and duration of hospital stay. Both groups demonstrated similar 14-day mortality (11.5% in the EI group vs 15.7% in the NEI group, p=0.29). The mean time to defervescence was significantly reduced in the EI group (4 days in the EI group vs 6 days in the NEI group, p=0.01); no significant differences between groups were noted in the other secondary outcomes. An Acute Physiology and Chronic Health Evaluation II score of 29.5 or higher was found to strongly predict 14-day mortality (p=0.03) by Classification and Regression Tree analysis. In the post hoc analyses, a 14-day mortality benefit was demonstrated in patients in the EI group in whom infectious organisms were identified (mortality rate 9.3% in the EI group vs 22.4% in the NEI group, p=0.01) and in whom respiratory tract infection was diagnosed (mortality rate 8.9% in the EI group vs 18.7% in the NEI group, p=0.02)., Conclusion: Both the EI and NEI groups demonstrated similar 14-day mortality. Post hoc subgroup analysis revealed a mortality benefit in patients in the EI group who had infectious organisms identified or were diagnosed with respiratory tract infections., (© 2016 Pharmacotherapy Publications, Inc.)

We report a significantly higher occurrence of adverse events associated with prolonged courses of piperacillin-tazobactam compared with other antibacterial agents used for pediatric outpatient parenteral antimicrobial therapy. These adverse events were characterized by a constellation of clinical findings including fever, hematologic abnormalities and transaminitis. Adverse events related to piperacillin-tazobactam should be considered in patients who develop a febrile illness associated with a prolonged course of therapy.

Piperacillin/tazobactam (TZP) as an alternative treatment to carbapenems for infections involving extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-PE) remains debated. In this study, the probabilities of pharmacodynamic (PD) target attainment with different TZP regimens in ESBL-producing Escherichia coli (ESBL-Ec) and Klebsiella pneumoniae (ESBL-Kp) were evaluated in the context of pyelonephritis. Minimum inhibitory concentrations (MICs) of 144 ESBL-Ec and 111 ESBL-Kp from pyelonephritis were measured, and two previously published population pharmacokinetic models were used to determine by Monte Carlo simulation the probabilities of reaching two PD targets (50%fT >MIC and 100%fT >MIC ) with TZP doses of 4 g three times daily and 4.5 g four times daily given as short (1 h) or prolonged (4 h) infusions or as 12-18 g/day continuous infusions. Only MICs of the 133 ESBL-Ec and 74 ESBL-Kp strains susceptible to TZP according to inhibition zone diameter were considered for the simulations. Results were similar with the two models, and only prolonged and continuous infusions allowed to reach 50%fT >MIC with a probability of >90% irrespective of bacterial species. Continuous infusion and prolonged infusion combined with the maximum dosage were the only condition allowing to achieve 100%fT >MIC with a probability of >70% with this population of ESBL-Ec. A probability of >90% to reach 100%fT >MIC with ESBL-Kp could be obtained only with the 18 g/day continuous-infusion regimen. TZP may be used for treatment for mild pyelonephritis involving susceptible ESBL-Ec provided that administration modalities are optimised. Conversely, for ESBL-Kp the risk of treatment failure may be higher, supporting the use of continuous infusion., (Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Tazobactam/piperacillin (TAZ/PIPC) is widely used in the treatment of infectious disease. In this study, three hundred and sixty-three patients who were treated with the recommended dose of TAZ/PIPC were investigated for the proportion of time above the minimum inhibitory concentration (%TAM) and the frequency of renal and liver dysfunction. Of the whole patient population, 5.23%, exhibited increased creatinine levels, 9.37% and 8.82% exhibited increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, respectively. The patients who exhibited high serum creatinine (SCr) levels before administration, exhibited significant increases of AST (p=0.0121). The patients who exhibited low albumin levels before administration, exhibited significant decreases in renal function (p=0.0041). In the case of a breakpoint (BP) of 64 μg/mL, the arrival probabilities of %TAM of 30% and 50% were 99.4% and 76.9%, respectively. We suggested that the dose of TAZ/PIPC should be adjusted according to the interview form finding and a %TAM>50% (maximal bactericidal action).

Tazobactam/piperacillin (TAZ/PIPC) is a combination antibiotic frequently used to treat pneumonia. It has recently been reported that TAZ/PIPC worsens renal function in patients with existing renal impairment. Creatinine clearance is generally between 10 and 40 mL/min in Japanese patients, so TAZ/PIPC is given at a dose of 2.25 g three times daily or 4.5 g twice daily. If pneumonia is severe or intractable, the dose frequency may be increased to 2.25 g four times daily and 4.5 g three times daily. We examined the effect of these different dosing regimens on renal function. We studied a cohort of 57 patients with impaired renal function hospitalized with pneumonia and treated with TAZ/PIPC between January 2015 and November 2016. Patients were classified into four groups according to TAZ/PIPC dose: 2.25 g three times daily (Group A); 2.25 g four times daily (B); 4.5 g twice daily (C) and 4.5 g three times daily (D). We examined the frequency of acute kidney injury (AKI) and treatment effectiveness. In Groups A, B, C and D, AKI occurred in 5.6%, 0.0%, 25.0% and 38.5% of patient. In groups C and D, hydration and dose reduction were required to address early signs of impending AKI. Our findings suggest that the higher TAZ/PIPC dose of 4.5 g was responsible for the decline in renal function, even if the dose frequency was reduced.

Background: Tungiasis is one of the neglected tropical diseases; it affects up to 40% of individuals living in societies with poor housing and sanitation standards. In endemic areas, Tunga infestation, which predominantly affects the periungual areas of the lower limbs in humans, is associated with considerable morbidity and poor quality of life., Case Presentation: A 78-year-old woman of African descent presented with pain, inflammation, suppuration, ulceration, and deformation of digits of all four limbs. She had a total of 1146 embedded sand fleas: 812 in lower limbs and 334 in her hands. She was febrile; her full blood count revealed pancytopenia and blood cultures were positive for Staphylococcus aureus and Streptococcus pyogenes isolates. Furthermore, she had severe hyponatremia. We applied 20% salicylated petroleum jelly followed by the manual removal of embedded sand fleas with a sterile needle. Intravenously administered piperacillin-tazobactam, topical ivermectin, ferrous sulfate, folic acid, tolvaptan, albendazole, multivitamins, and tetanus prophylaxis were instituted. She was discharged home after 16 days of hospitalization., Conclusions: Tungiasis is a neglected disease of concern in underprivileged societies that is preventable and curable. Early recognition and prompt treatment is crucial to prevent complications in this disease which may potentially mimic other conditions resulting in erroneous management.

Objectives: Population pharmacokinetic (popPK) analyses for piperacillin/tazobactam in neonates and infants of less than 2 months of age have been performed by our group previously. The results indicate that a dose of 44.44/5.56 mg/kg piperacillin/tazobactam every 8 or 12 h may not be enough for controlling infection in this population. In order to determine the appropriate dosing regimen and to provide a rationale for the development of dosing guidelines suitable for this population, further popPK studies of piperacillin/tazobactam would need to be conducted. The aim of the present study was to determine the appropriate dosing regimen and optimal sampling schedules in neonates and infants of less than 2 months of age., Methods: Pharmacodynamic profiling of piperacillin using Monte Carlo simulation was performed to explore the target attainment probability of different dosing regimens for infections caused by different isolated pathogens. D-optimal designs for piperacillin and tazobactam were conducted separately, and the times that overlapped were chosen as the final sampling scheme for future popPK studies in neonates and young infants of less than 2 months of age., Results: Our findings revealed that compared to the current empirical piperacillin/tazobactam dose regimen (50 mg/kg every 12 h by 5-min infusion in our hospital), the clinical outcome could be improved by increasing doses, increasing administration frequency, and prolonging intravenous infusion in neonates and infants of less than 2 months of age. The following optimal sampling windows were chosen as the final sampling scheme: 0.1-0.11, 0.26-0.29, 0.97-2.62, and 7.95-11.9 h administered every 12 h with 5-min infusion; 0.1-0.12, 0.39-0.56, 2.86-4.95, and 8.91-11.8 h administered every 12 h with 3-h infusion; 0.1-0.11, 0.22-0.29, 0.91-1.96, and 5.56-7.93 h administered every 8 h with 5-min infusion; 0.1-0.11, 0.38-0.48, 2.54-3.82, and 6.86-7.93 h administered every 8 h with 3-h infusion; 0.1-0.11, 0.25-0.28, 0.84-1.69, and 4.55-5.94 h administered every 6 h with 5-min infusion; and 0.1-0.11, 0.37-0.54, 3.13-3.72, and 5.57-5.99 h administered every 6 h with 3-h infusion., Conclusions: The dosing regimen and sampling schedules proposed in this study should be evaluated in future popPK studies of piperacillin/tazobactam in neonates and infants. To the best of our knowledge, this is the first study that combined optimal sampling design with Monte Carlo simulation for designing popPK studies of piperacillin/tazobactam.

Study Objective: To evaluate the association of the development of acute kidney injury (AKI) when piperacillin-tazobactam is used in combination with vancomycin compared with vancomycin with or without a β-lactam., Design: Meta-analysis of 15 observational cohort studies., Patients: A total of 3258 adult inpatients who received vancomycin + piperacillin-tazobactam versus vancomycin alone (10 studies); vancomycin + piperacillin-tazobactam versus vancomycin + β-lactam (four studies); or vancomycin + piperacillin-tazobactam versus vancomycin alone or vancomycin + other antibiotics (one study)., Measurements and Main Results: The PubMed, Embase, Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases, as well as meeting proceedings, were searched (1966-June 1, 2016). Quality of studies was assessed by using the Newcastle-Ottawa Quality Assessment Scale (NOQAS). The primary outcome of this meta-analysis was to evaluate the association of development of AKI with the combined use of piperacillin-tazobactam and vancomycin. A subgroup analysis was also performed that examined the outcome by comparison groups (vancomycin alone or vancomycin + β-lactam). Sensitivity analysis was performed to explore if the results differed based on removal of abstracts and removal of low-quality studies (NOQAS scores of 6 or lower). All analyses were performed using the random effects model. NOQAS scores for the 15 studies ranged from 3-7 points (of a total of 9). Overall, there was an association with the development of AKI with vancomycin + piperacillin-tazobactam compared with vancomycin ± β-lactam (odds ratio [OR] 3.649, 95% confidence interval [CI] 2.157-6.174; I 2 = 83.5%, p<0.001). The association remained significant when abstracts were removed (OR 3.498, 95% CI 1.747-7.003, I 2 = 82.3%, p<0.001) and when low-quality studies were removed (OR 4.596, 95% CI 2.929-7.212, I 2 = 0%, p<0.001). The association for the development of AKI with vancomycin + piperacillin-tazobactam compared with vancomycin alone was significant (OR 3.980, 95% CI 2.749-5.763, I 2 = 31.4%, p<0.001), although the association did not remain significant for the vancomycin + β-lactam subgroup (OR 3.029, 95% CI 0.942-9.738, I 2 = 82.3%, p=0.063)., Conclusion: Vancomycin + piperacillin-tazobactam was associated with an increased risk of AKI compared with vancomycin ± β-lactam. Practitioners need to be vigilant about this association when prescribing this combination of antibiotics., (© 2016 Pharmacotherapy Publications, Inc.)

Background: We report a case of a rare complication of acute appendicitis with perforation through the abdominal wall. The case points out that an intraabdominal origin should be considered in patients presenting with rapidly spreading soft tissue infections of the trunk., Case Presentation: A 58-year-old European woman presented to our hospital with a 1-week history of severe abdominal pain accompanied by rapidly spreading erythema and emphysema of the lower abdomen. On admission, the patient was in septic shock with leukocytosis and elevation of C-reactive protein. Among other diagnoses, necrotizing fasciitis was suspected. Computed tomography showed a large soft tissue infection with air-fluid levels spreading through the lower abdominal wall. During the operation, we found a perforated appendicitis breaking through the fascia and causing a rapidly progressive soft tissue infection of the abdominal wall. Appendicitis was the origin of the soft tissue infection. The abdominal wall was only secondarily involved., Conclusions: Even though perforated appendicitis as an etiology of a rapidly progressive soft tissue infection of the abdominal wall is very rare, it should be considered in the differential diagnosis of abdominal wall cellulitis. The distinction between rapidly spreading subcutaneous infection with abscess formation and early onset of necrotizing fasciitis is often difficult and can be confirmed only by surgical intervention.

Study Objective: It is unknown if β-lactam monotherapy is sufficient for complicated intra-abdominal infections or if broader coverage is required, such as with vancomycin. This study sought to determine the clinical outcomes of piperacillin/tazobactam (PIP/TAZ) monotherapy compared to combination therapy with vancomycin and PIP/TAZ for complicated intra-abdominal infections among patients within a surgical intensive care unit (ICU)., Design: Retrospective cohort study., Setting: Three surgical ICUs at a tertiary academic medical center., Patients: Four hundred seventeen patients with a secondary peritonitis identified by International Classification of Diseases, Ninth Revision codes who received either PIP/TAZ monotherapy (228 patients) or PIP/TAZ and vancomycin combination therapy (189 patients)., Measurements and Main Results: The primary outcome was day 28 clinical cure; secondary outcomes included day 7 clinical cure, length of stay (LOS), and mortality. There were no statistically significant differences between the monotherapy and combination therapy groups with respect to day 28 clinical cure (33.9% vs 25.5%, p=0.064), day 7 clinical cure (23.6% vs 17.6%, p=0.14), or 28-day mortality (7% vs 7.9%, p=0.72). LOS in the ICU was significantly shorter in the monotherapy group (6 days) compared with the combination therapy group (7 days; p=0.04); however, hospital LOS was not significantly different., Conclusions: No difference was observed in clinical cure rates at day 28 or day 7 between those who received PIP/TAZ monotherapy compared to PIP/TAZ and vancomycin combination therapy., (© 2016 Pharmacotherapy Publications, Inc.)

Background: Controversies remain regarding optimal dosing and the need for plasma concentration measurements when treating intensive care patients with beta-lactam antibiotics., Methods: We studied ICU patients treated with either antibiotic, excluding patients on renal replacement therapy. Antibiotic concentrations were measured at the mid and end of the dosing interval, and repeated after 2-3 days when feasible. Glomerular filtration rate (GFR) was estimated from plasma creatinine and cystatin C, GFR calculated from cystatin C (eGFR) and measured creatinine clearance (CrCl). Measured concentrations were compared to the clinical susceptible breakpoints for Pseudomonas aeruginosa, 16 and 2 mg/l for piperacillin and meropenem respectively., Results: We analysed 33 and 31 paired samples from 20 and 19 patients treated with piperacillin-tazobactam and meropenem respectively. Antibiotic concentrations at the mid and end of the dosing interval were for piperacillin, 27.0 (14.7-52.9) and 8.6 (2.7-30.3); and for meropenem, 7.5 (4.7-10.2) and 2.4 (1.0-3.5). All values median (interquartile range) and concentrations in mg/l. The percentage of measured concentrations below the breakpoint at the mid and end of the dosing interval were for piperacillin, 27% and 61%; and for meropenem, 6% and 48%. Lower estimates of GFR were associated with higher concentrations but concentrations varied greatly between patients with similar GFR. The correlation with terminal concentration half-life was similar for eGFR and CrCl., Conclusions: With standard doses of meropenem and piperacillin-tazobactam, plasma concentrations in ICU patients vary > 10-fold and are suboptimal in a significant percentage of patients. The variation is large also between patients with similar renal function., (© 2016 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Background: Gram-negative microorganisms are uncommon pathogens responsible for infective endocarditis. Pseudomonas mendocina, a Gram-negative water-borne and soil-borne bacterium, was first reported to cause human infection in 1992. Since then, it has rarely been reported as a human pathogen in the literature. We describe the first case of native valve infective endocarditis due to P. mendocina in the USA., Case Presentation: A 57-year-old white man presented with bilateral large leg ulcers, fever, and marked leukocytosis. His past medical history included gout and chronic alcohol use. P. mendocina was isolated from his blood cultures. A comprehensive review of P. mendocina infection in the literature was performed. A total of eight cases of P. mendocina infection were reported in the literature. More than two-thirds of the cases of P. mendocina septicemia were associated with native valve infective endocarditis. Thus, an echocardiogram was performed and demonstrated mitral valve endocarditis with mild mitral insufficiency. His leg wounds were debrided and were probably the source of P. mendocina bacteremia. Unlike Pseudomonas aeruginosa, P. mendocina is susceptible to third-generation cephalosporins. Our patient received a 6-week course of antimicrobial therapy with a favorable clinical outcome., Conclusions: Our reported case and literature review illuminates a rare bacterial cause of infective endocarditis secondary to P. mendocina pathogen. Native cardiac valves were affected in all reported cases of infective endocarditis, and a majority of affected heart valves were left-sided. The antibiotics active against P. mendocina are different from those that are active against P. aeruginosa, and they notably include third-generation cephalosporins. The outcome of all reported cases of P. mendocina was favorable and no mortality was described.

Introduction To enhance the probability of pharmacodynamic target attainment, piperacillin-tazobactam can be administered as either a continuous or extended-infusion dosage regimen for the treatment of gram-negative infections. Four hour extended-infusions of piperacillin-tazobactam 3.375 g administered intravenously (IV) every 8 h have been widely studied as an alternative to conventional, intermittent dosage regimens with largely favorable outcomes. Objective To assess the clinical and economic impact of a novel 3-h extended-infusion piperacillin-tazobactam dosing strategy for the treatment of gram-negative infections. Setting 433-bed community hospital in Lexington, KY. Methods Retrospective cohort study before and after the implementation of an alternative dosing protocol using a 3-h infusion of piperacillin-tazobactam 3.375 g IV every 6 h. Main outcome measures The primary outcome was in-hospital mortality. Secondary outcomes include length of stay, ICU length of stay, 30-day all-cause hospital readmissions, total cost per admission, complications, and a composite of in-hospital mortality and readmission within 30 days of discharge. Results Readmission within 30 days of hospital discharge was significantly reduced in the extended-infusion arm (1.2 vs. 13.7 %, P = 0.002). A composite endpoint of death or readmission was lower among patients who received the extended-infusion dosing regimen [ORadj 0.20; 95 % CI (0.07-0.57)]. However this was likely driven by reductions in readmission. Conclusion An alternative regimen of extended-infusion piperacillin-tazobactam resulted in a significant reduction in 30-day all-cause hospital readmission. These results indicate that 3-h infusions of piperacillin-tazobactam 3.375 g IV every 6 h may represent a clinically effective alternative to other commonly used regimens and results in fewer readmissions within 30 days.

Given the inconsistent clinical findings, our goal was to characterize the pharmacodynamics (PDs) of prolonged-infusion piperacillin-tazobactam (TZP) in an in vitro pharmacodynamic model of Pseudomonas aeruginosa. Specifically, the study was designed to investigate the influence of MIC on the activity of prolonged-infusion TZP using pharmacokinetics (PKs) consistent with a non-critically ill patient population. There was no benefit with prolonged- compared with standard-infusion TZP against isolates with susceptible MICs of 8 or 16 mg/L. However, prolonged-infusion TZP produced more than two times the final bacterial kill against less susceptible isolates with an intermediate MIC of 32 mg/L. The PDs of TZP were well described by a sigmoid Emax model (r(2) = 0.84) where %ƒT>MIC thresholds of 27 and 75% were associated with bacteriostatic and bactericidal effects, respectively. However, the well-established PD relationship with %ƒT>MIC was not observed with prolonged-infusion TZP. In conclusion, this study characterizes the targeted benefits of prolong-infusion TZP based on pathogen MIC, and supports the assertion that the benefits are selective and most likely observed in patients with less susceptible pathogens or altered PKs.

Therapeutic drug monitoring for critically ill patients receiving piperacillin/tazobactam is described as a useful tool. However, the minimum inhibitory concentration of piperacillin depends on a sufficiently high concentration of tazobactam in case of β-lactamase-producing strains. Therefore, the relationship between piperacillin and tazobactam concentrations was assessed in a heterogeneous group of critically ill patients. Sixty patients with severe infections receiving 4.5 g of piperacillin/tazobactam 2-3 times daily by intermittent infusion were included in this prospective observational study (NCT01793012). Over 4 days, multiple serum samples were obtained to determine the total piperacillin and tazobactam concentrations. The target ranges were defined as trough levels >16 mg/L (>22.5 mg/L) and >4 mg/L (>5.7 mg/L) for the calculated unbound concentrations (measured total concentrations) of piperacillin and tazobactam, respectively. Despite a high correlation coefficient (r = 0.93) comparing piperacillin and tazobactam trough levels, the piperacillin/tazobactam quotients varied between ca. 1 and 10. From linear regression analysis of piperacillin versus tazobactam values, it follows that a piperacillin trough level of 22.5 mg/L might be associated with tazobactam trough levels ranging from 1.5 mg/L to 10.1 mg/L. A 70 mg/L threshold for total piperacillin trough levels would be necessary to ensure that tazobactam concentrations are >5.7 mg/L. Because of the observed variability of piperacillin/tazobactam quotients, defining the total piperacillin target range ≥70 mg/L might be useful to ensure that tazobactam concentrations do not fall below 5.7 mg/L. Further studies are necessary to confirm that the used therapeutic ranges are associated with optimal outcomes in critically ill patients., (Copyright © 2016 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.)

Background & Objectives: Fluoroquinolone resistance in both Gram-positive and Gram-negative bacteria has increased with the widespread use of fluoroquinolones. Fluoroquinolone resistance in Gram-negative bacilli has been widely studied, though staphylococci and enterococci are also notably resistant. Enterococci being the second most common cause of healthcare-associated urinary tract infections (UTIs) fluoroquinolones are often the drug of choice. This study was undertaken to assess the risk factors associated with fluoroquinolone-resistant enterococcal UTI in a tertiary level health facility in north India., Methods: A total of 365 patients with UTI caused by enterococci were studied over a period of two years. Patients with ciprofloxacin-resistant and susceptible UTI were considered as cases and controls, respectively. Resistance profile of the isolates against common antibiotics was studied by minimum inhibitory concentration (MIC) determination. Mechanisms for fluoroquinolone resistance was studied by efflux pump inhibitor activity and multiplex PCR targeting the qnr genes., Results: A total of 204 (55.89%) cases and 161 (44.1%) controls were identified. The fluoroquinolone-resistant isolates were significantly resistant to ampicillin, high strength aminoglycosides and vancomycin. The majority (78%) of the resistant isolates showed efflux pump activity. Treatment in indoor locations, presence of urinary catheters and pregnancy along with recent exposure to antibiotics especially fluoroquinolones, third generation cephalosporins and piperacillin-tazobactam were identified as independent risk factors., Interpretation & Conclusions: Our results showed that fluoroquinolone resistance in enterococcal UTI was largely associated with indoor usage of antibiotics and use of indwelling devices. Knowledge of risk factors is important to curb this emergence of resistance.

Background: Pathophysiological changes in critically ill patients can cause severely altered pharmacokinetics and widely varying antibiotic exposures. The impact of altered pharmacokinetics on bacterial killing and resistance has not been characterized in the dynamic hollow-fibre in vitro infection model (HFIM)., Methods: A clinical Pseudomonas aeruginosa isolate (piperacillin MIC 4 mg/L) was studied in the HFIM (inoculum ∼10(7) cfu/mL). Pharmacokinetic profiles of three piperacillin dosing regimens (4 g 8-, 6- and 4-hourly, 30 min intravenous infusion) as observed in critically ill patients with augmented renal clearance (ARC), normal renal function or impaired renal function (creatinine clearances of 250, 110 or 30 mL/min, respectively) were simulated over 7 days. The time courses of total and less-susceptible populations and MICs were determined. Mechanism-based modelling was performed in S-ADAPT., Results: For all regimens with ARC and regimens with 8- or 6-hourly dosing with normal renal function, initial killing of ≤∼2 log10 was followed by regrowth to 10(8)-10(9) cfu/mL at 48 h. For 8- and 6-hourly dosing at normal renal function, the proportion of less-susceptible colonies increased ∼10-100-fold above those in ARC and control arms. Regimens achieving an fCmin of ≥5× MIC resulted in bacterial killing of 3-4 log10 without regrowth and suppressed less-susceptible populations to ≤∼2 log10. The mechanism-based model successfully quantified the time course of bacterial growth, killing and regrowth., Conclusions: Only high piperacillin concentrations prevented regrowth of P. aeruginosa. Individualized dosing regimens that account for altered pharmacokinetics and aim for higher-than-standard antibiotic exposures to achieve an fCmin of ≥5× MIC were required to maximize bacterial killing and suppress emergence of resistance., (© 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.)

Background: β-lactam antibiotics may necessitate higher than licensed drug doses to achieve therapeutic exposures in critically ill patients. Therapeutic drug monitoring can be used to guide dosing so as to maximise therapeutic effect whilst reducing the likelihood of exposure-related toxicity., Methods: A retrospective review of critically ill patients identified those that received higher than licensed doses of either meropenem (3-6 g/day) or piperacillin-tazobactam (16 g-2 g/day) (i.e. high-dose group) guided by therapeutic drug monitoring. β-lactam-associated toxicities were compared with a patient group of similar age, sex, body mass index and admission diagnosis that received licensed doses of either antibiotic., Results: Mean daily doses were more than 40% higher in the high-dose groups for each antibiotic. There were no significant differences between the high-dose and licensed-dose groups in terms of hepatocellular derangement (17.9% vs. 31.8%, P=0.25 for meropenem and 17.4% vs. 16.0%, P=0.90 for piperacillin-tazobactam), cholestasis (28.0% vs. 13.6%, P=0.32 for meropenem and 13.0% vs. 4.0%, P=0.26 for piperacillin-tazobactam), need for continuous renal replacement therapy (0% vs. 9.1%, P=0.10 for meropenem and 0% vs. 8.0%, P=0.16 for piperacillin-tazobactam), seizure incidence (7.1% vs. 4.5%, P=0.70 for meropenem and nil for either piperacillin-tazobactam group), thrombocytopenia (9.1% vs. 10.7%, P=0.85 for meropenem and 4.0% vs. 4.3% for piperacillin-tazobactam), or neutropenia (4.5% vs. 3.6%, P=0.95 for meropenem and 0.0% vs. 4.3% for piperacillin-tazobactam)., Conclusions: Higher than licensed doses of meropenem and piperacillin-tazobactam guided by therapeutic drug monitoring were not associated with additional toxicities. Larger prospective studies are required to confirm the clinical utility of higher than licensed dosing.

Background and Objectives: Infection is the most common cause of death in severe AKI, but many patients receiving continuous RRT do not reach target antibiotic concentrations in plasma. Extended infusion of β-lactams is associated with improved target attainment in critically ill patients; thus, we hypothesized that extended infusion piperacillin-tazobactam would improve piperacillin target attainment compared with short infusion in patients receiving continuous RRT., Design, Setting, Participants, & Measurements: We conducted an institutional review board-approved observational cohort study of piperacillin-tazobactam pharmacokinetics and pharmacodynamics in critically ill patients receiving continuous venovenous hemodialysis and hemodiafiltration at three tertiary care hospitals between 2007 and 2015. Antibiotic concentrations in blood and/or dialysate samples were measured by liquid chromatography, and one- and two-compartment pharmacokinetic models were fitted to the data using nonlinear mixed effects regression. Target attainment for piperacillin was defined as achieving four times the minimum inhibitory concentration of 16 μg/ml for >50% of the dosing cycle. The probabilities of target attainment for a range of doses, frequencies, and infusion durations were estimated using a Monte Carlo simulation method. Target attainment was also examined as a function of patient weight and continuous RRT effluent rate., Results: Sixty-eight participants had data for analysis. Regardless of infusion duration, 6 g/d piperacillin was associated with ≤45% target attainment, whereas 12 g/d was associated with ≥95% target attainment. For 8 and 9 g/d, target attainment ranged between 68% and 85%. The probability of target attainment was lower at higher effluent rates and patient weights. For all doses, frequencies, patient weights, and continuous RRT effluent rates, extended infusion was associated with higher probability of target attainment compared with short infusion., Conclusions: Extended infusions of piperacillin-tazobactam are associated with greater probability of target attainment in patients receiving continuous RRT., (Copyright © 2016 by the American Society of Nephrology.)

Objective: The study was to establish a population pharmacokinetic (PPK) model of piperacillin (PIP) and tazobactam (TAZ) that explain pharmacokinetic variability and to propose optimized dosage regimens in patients with nosocomial infections., Methods: In total, 310 PIP and 280 TAZ concentration-time points were collected at steady state over multiple dosing intervals from 50 patients who received PIP/TAZ infused within 30 min or over 3 h. Drug analysis was performed by high-performance liquid chromatography (HPLC). Nonlinear mixed effects modeling was employed to develop PPK model and 1000 Monte Carlo simulation was used to predict the probability of target attainment (PTA) with a target time of non-protein-bound concentration above MIC > 50 % of the dosing interval., Results: A model with one-compartment model had the best predictive performance for the PPK model. The population estimates of PIP were 13.8 L/h (31.1 %) for clearance (CL) and 21.7 L (38 %) for volume of distribution (V). The population estimates of TAZ were 9.3 L/h (29.1 %) for CL and 16 L (35.3 %) for V. Influence of creatinine clearance (CLcr) and body weight were identified as important covariates for PIP/TAZ CL and V, respectively. A 30-min infusion of 4 g every 6 h achieved robust (≥90 %) PTAs for MIC ≤ 16 mg/L. As an alternative mode of administration, a 3-h infusion of 4 g every 6 h achieved robust PTAs for Pseudomonas aeruginosa and Klebsiella pneumoniae., Conclusions: Prolonged infusions achieved better PTAs compared with shorter infusions at similar daily doses. This benefit was most pronounced for MICs between 16 and 40 mg/L.