Analysis of IV Drugs in the Hospital Workflow by Raman Spectroscopy: The Case of Piperacillin and Tazobactam.

Medical errors associated with IV preparation and administration procedures in a hospital workflow can even cost human lives due to the direct effect they have on patients. A large number of such incidents, which have been reported in bibliography up to date, indicate the urgent need for their prevention. This study aims at proposing an analytical methodology for identifying and quantifying IV drugs before their administration, which has the potential to be fully harmonized with clinical practices. More specifically, it reports on the analysis of a piperacillin (PIP) and tazobactam (TAZ) IV formulation, using Raman spectroscopy. The simultaneous analysis of the two APIs in the same formulation was performed in three stages: before reconstitution in the form of powder without removing the substance out of the commercial glass bottle (non-invasively), directly after reconstitution in the same way, and just before administration, either the liquid drug is placed in the infusion set (on-line analysis) or a minimal amount of it is transferred from the IV bag to a Raman optic cell (at-line analysis). Except for the successful identification of the APIs in all cases, their quantification was also achieved through calibration curves with correlation coefficients ranging from 0.953 to 0.999 for PIP and from 0.965 to 0.997 for TAZ. In any case, the whole procedure does not need more than 10 min to be completed. The current methodology, based on Raman spectroscopy, outweighs other spectroscopic (UV/Vis, FT-IR/ATR) or chromatographic (HPLC, UHPLC) protocols, already applied, which are invasive, costly, time-consuming, not environmentally friendly, and require specialized staff and more complex sample preparation procedures, thus exposing the staff to hazardous materials, especially in cases of cytotoxic drugs. Such an approach has the potential to bridge the gap between experimental setup and clinical implementation through exploitation of already developed handheld devices, along with the presence of digital spectral libraries.

Detection of meningoencephalitis caused by Listeria monocytogenes with ischemic stroke-like onset using metagenomics next-generation sequencing: A case report.

RATIONALE: Listeria monocytogenes (L. monocytogenes) is a compatible intracellular bacterial pathogen that can invade different mammalian cells and reach the central nervous system (CNS), leading to meningoencephalitis and brain abscesses. In the diagnosis of L. monocytogenes meningoencephalitis (LMM), conventional tests are often reported as negative due to antibiotic therapy or low bacterial content in cerebrospinal fluid. To date, prompt diagnosis and accurate treatment remain a challenge for patients with Listeria infections. PATIENT CONCERNS: Here, we report a case of a 64-year-old male diagnosed with LMM by using metagenomics next-generation sequencing (mNGS). DIAGNOSIS: LMM was confirmed by mNGS analysis of cerebrospinal fluid. INTERVENTIONS: The patient was treated with piperacillin and sensitive antibiotics. OUTCOMES: The patient could walk independently about 1 month after admission and was discharged from the hospital. LESSONS: This case highlights the value of mNGS in the diagnosis of LMM and emphasizes the inadequate sensitivity of conventional diagnostic methods for Listeria infection.

Estimation of Ontogeny Functions for Renal Transporters Using a Combined Population Pharmacokinetic and Physiology-Based Pharmacokinetic Approach: Application to OAT1,3.

To date, information on the ontogeny of renal transporters is limited. Here, we propose to estimate the in vivo functional ontogeny of transporters using a combined population pharmacokinetic (popPK) and physiology-based pharmacokinetic (PBPK) modeling approach called popPBPK. Clavulanic acid and amoxicillin were used as probes for glomerular filtration, combined glomerular filtration, and active secretion through OAT1,3, respectively. The predictive value of the estimated OAT1,3 ontogeny function was assessed by PBPK predictions of renal clearance (CLR) of other OAT1,3 substrates: cefazolin and piperacillin. Individual CLR post-hoc values, obtained from a published popPK model on the concomitant use of clavulanic acid and amoxicillin in critically ill children between 1 month and 15 years, were used as dependent variables in the popPBPK analysis. CLR was re-parameterized according to PBPK principles, resulting in the estimation of OAT1,3-mediated intrinsic clearance (CLint,OAT1,3,invivo) and its ontogeny. CLint,OAT1,3,invivo ontogeny was described by a sigmoidal function, reaching half of adult level around 7 months of age, comparable to findings based on renal transporter-specific protein expression data. PBPK-based CLR predictions including this ontogeny function were reasonably accurate for piperacillin in a similar age range (2.5 months-15 years) as well as for cefazolin in neonates as compared to published data (%RMSPE of 21.2 and 22.8%, respectively and %PE within ±50%). Using this novel approach, we estimated an in vivo functional ontogeny profile for CLint,OAT1,3,invivo that yields accurate CLR predictions for different OAT1,3 substrates across different ages. This approach deserves further study on functional ontogeny of other transporters.

Significant interaction between high-dose methotrexate and high-dose piperacillin-tazobactam causing reversible neurotoxicity and renal failure in an osteosarcoma patient.

INTRODUCTION: Pharmacokinetic interaction of high-dose methotrexate (MTX) and other concomitantly administered renally secreted medicinal products may lead to insufficient methotrexate serum level decrease and significant MTX toxicity. CASE REPORT: We report the case of an 18-year-old male patient treated with high-dose MTX for an osteosarcoma and with high-dose piperacillin-tazobactam at the same time. MTX serum levels were severely elevated 24 hours after the MTX infusion and did not decrease in accordance with the specific calcium folinate rescue protocol. The patient experienced renal failure accompanied by neurological symptoms, most consistent with MTX-related renal and CNS toxicity.Management and outcome: After discontinuation of piperacillin-tazobactam, intensified calcium folinate rescue therapy, and IV hydration, the MTX serum levels decreased appropriately, and toxicity symptoms resolved. DISCUSSION: Severe MTX-related toxicity, caused by drug-drug interaction, suggests that the concomitant use of high-dose MTX and high-dose piperacillin-tazobactam should be avoided generally.

The ONTAI study - a survey on antimicrobial dosing and the practice of therapeutic drug monitoring in German intensive care units.

PURPOSE: Optimization of antibiotic therapy is still urgently needed in critically ill patients. The aim of the ONTAI survey (online survey on the use of Therapeutic Drug Monitoring of antibiotics in intensive care units) was to evaluate which strategies intensive care physicians in Germany use to improve the quality of antibiotic therapy and what role a Therapeutic Drug Monitoring (TDM) plays. METHODS: Among the members of the German Society for Anaesthesiology and the German Society for Medical Intensive Care Medicine and Emergency Medicine, a national cross-sectional survey was conducted using an online questionnaire. RESULTS: The questionnaire was completely answered by 398 respondents. Without TDM, prolonged infusion was judged to be the most appropriate dosing regimen for beta lactams. A TDM for piperacillin, meropenem and vancomycin was performed in 17, 22 and 75% of respondents, respectively. For all beta lactams, a TDM was requested more often than it was available. There was great uncertainty as to the optimal pharmacokinetic/pharmacodynamic index for beta-lactams. 86% of the respondents who received minimal inhibitory concentrations adapted the therapy accordingly. CONCLUSION: German intensive care physicians are convinced of TDM for dose optimization. However, practical implementation, the determination of MICs and defined target values are still lacking.

Molecular Adsorbent Recirculating System Therapy with Continuous Renal Replacement Therapy Enhanced Clearance of Piperacillin in a Pediatric Patient and Led to Failure to Attain Pharmacodynamic Targets.

Molecular adsorbent recirculating system (MARS), an extracorporeal support device used in patients with liver failure, specifically removes albumin-bound molecules, including antibiotics. Case reports in adult patients showed that MARS enhances the clearance of piperacillin. However, for those patients, pharmacodynamic targets were achieved when piperacillin/tazobactam was administered as extended infusions over 3-4 hours. In contrast, piperacillin/tazobactam is typically given as short intermittent infusions in children. No reports describe the effect of MARS on piperacillin pharmacokinetics or pharmacodynamic target attainment in pediatric patients with liver failure. This case report describes the effects of MARS on piperacillin clearance and target attainment in a child with liver failure. It was noted that MARS, in conjunction with continuous renal replacement therapy (CRRT), enhanced the clearance of piperacillin when compared with CRRT alone (6.4-7.4 L/hr vs 3.0 L/hr). Pharmacodynamic targets were not attained during MARS-CRRT cycles with free piperacillin concentrations being above 64 µg/ml for < 50% of dosing intervals, the goal target. We performed simulation analysis to identify a dosing regimen to optimize target attainment. For this patient, doses 3 times what she received over 3-hour extended infusions and an additional dose within 5 hours of cycle initiation would have led to target attainment throughout the MARS-CRRT cycles.

Linguistic and cultural adaptation to the Portuguese language of antimicrobial dose adjustment software.

OBJECTIVE: To adapt an antibiotic dose adjustment software initially developed in English, to Portuguese and to the Brazilian context. METHODS: This was an observational, descriptive study in which the Delphi method was used to establish consensus among specialists from different health areas, with questions addressing the visual and operational aspects of the software. In a second stage, a pilot experimental study was performed with the random comparison of patients for evaluation and adaptation of the software in the real environment of an intensive care unit, where it was compared between patients who used the standardized dose of piperacillin/tazobactam, and those who used an individualized dose adjusted through the software Individually Designed and Optimized Dosing Strategies. RESULTS: Twelve professionals participated in the first round, whose suggestions were forwarded to the software developer for adjustments, and subsequently submitted to the second round. Eight specialists participated in the second round. Indexes of 80% and 90% of concordance were obtained between the judges, characterizing uniformity in the suggestions. Thus, there was modification in the layout of the software for linguistic and cultural adequacy, minimizing errors of understanding and contradictions. In the second stage, 21 patients were included, and there were no differences between doses of piperacillin in the standard dose and adjusted dose Groups. CONCLUSION: The adapted version of the software is safe and reliable for its use in Brazil.

Linguistic and cultural adaptation to the Portuguese language of antimicrobial dose adjustment software / Adaptação linguística e cultural para a língua portuguesa de um software para ajuste de dose de antimicrobianos

ABSTRACT Objective To adapt an antibiotic dose adjustment software initially developed in English, to Portuguese and to the Brazilian context. Methods This was an observational, descriptive study in which the Delphi method was used to establish consensus among specialists from different health areas, with questions addressing the visual and operational aspects of the software. In a second stage, a pilot experimental study was performed with the random comparison of patients for evaluation and adaptation of the software in the real environment of an intensive care unit, where it was compared between patients who used the standardized dose of piperacillin/tazobactam, and those who used an individualized dose adjusted through the software Individually Designed and Optimized Dosing Strategies. Results Twelve professionals participated in the first round, whose suggestions were forwarded to the software developer for adjustments, and subsequently submitted to the second round. Eight specialists participated in the second round. Indexes of 80% and 90% of concordance were obtained between the judges, characterizing uniformity in the suggestions. Thus, there was modification in the layout of the software for linguistic and cultural adequacy, minimizing errors of understanding and contradictions. In the second stage, 21 patients were included, and there were no differences between doses of piperacillin in the standard dose and adjusted dose Groups. Conclusion The adapted version of the software is safe and reliable for its use in Brazil.

RESUMO Objetivo Adaptar um software de ajuste de dose de antibióticos inicialmente elaborado em língua inglesa para o português e a conjuntura brasileira. Métodos Trata-se de estudo observacional, descritivo, em que foi utilizado o método Delphi para estabelecer consenso entre especialistas de diferentes áreas da saúde, com perguntas que abordaram os aspectos visuais e operacionais do software. Em uma segunda etapa, foi realizado um estudo piloto, experimental, com alocação aleatória dos pacientes, para avaliação e adaptação do software em ambiente real de uma unidade de tratamento intensivo, onde foram comparadas diferenças entre pacientes que utilizaram dose padronizada usual de piperacilina/tazobactam, e os que utilizaram a dose individualizada ajustada por meio do software Individually Designed Optimum Dosing Strategies. Resultados Participaram da primeira rodada 12 profissionais cujas sugestões foram encaminhadas ao desenvolvedor do software para adequação e ajustes, e posteriormente submetidas à segunda rodada. Oito especialistas participaram da segunda rodada. Foram obtidos índices de 80% e 90% de concordância entre os juízes, caracterizando uniformidade nas sugestões. Dessa forma, houve modificação no layout do software para adequação linguística e cultural, minimizando erros de entendimento e contradições. Na segunda etapa, foram incluídos 21 pacientes, e não houve diferenças entre doses de piperacilina nos grupos dose padronizada e dose ajustada. Conclusão A versão adaptada do software é segura e confiável para seu uso no Brasil.

A Randomized, Open-Labeled, Prospective Controlled Study to Assess the Efficacy of Frontline Empirical Intravenous Piperacillin/Tazobactam Monotherapy in Comparison with Ceftazidime Plus Amikacin for Febrile Neutropenia in Pediatric Oncology Patients.

Background: Febrile neutropenia (FN) is the most common complication in pediatric oncology patients. Appropriate empirical antibiotics treatment is essential for treatment outcome. Methods: This study was a randomized prospective controlled study to demonstrate the efficacy of piperacillin/tazobactam (PIP/TZO) monotherapy compared with ceftazidime/amikacin in children with FN. Pediatric oncology patients at Chiang Mai University Hospital, diagnosed with FN, were randomized to receive either PIP/TZO 320 mg/kg/day divided every 8 hours or ceftazidime 100 mg/kg/ day divided every 8 hours plus amikacin 15 mg/kg/day once daily. Treatment responses were compared between the two groups. Results: One-hundred and eighteen febrile neutropenic episodes in 70 patients (42 males and 28 females) were enrolled. The median age was 7 (3-10) years. The early response and complete response to initial treatment were achieved in 48/59 (81.4%) episodes and 41/59 (69.5%) episodes in PIP/TZO group compared with 40/59 (67.8%) episodes and 33/59 (55.9%) episodes in ceftazidime/amikacin group (p-value 0.091 and 0.128, respectively). Treatment modification in PIP/TZO group was required in 18/59 (30.5%) compared with 26/59 (44.1%) patients in ceftazidime/amikacin group (p-value 0.128). Similarly, the duration of fever, duration of neutropenia and duration of antibiotics treatment were not significantly different between two groups. No serious adverse events were observed. Conclusion: The treatment responses of PIP/TZO monotherapy and ceftazidime/amikacin therapy were not significantly different. Both therapies were effective for FN in pediatric oncology patients.

Saturable elimination of piperacillin in critically ill patients: implications for continuous infusion.

The study aimed to evaluate saturation of piperacillin elimination in critically ill adult patients. Seventeen critically ill adult patients received continuous and intermittent infusion of piperacillin/tazobactam. Piperacillin plasma concentrations (n = 217) were analysed using population pharmacokinetic (PopPK) modelling. Post-hoc simulations were performed to evaluate the type I error rate associated with the study. Unseen data were used to validate the final model. The mean error (ME) and root mean square error (RMSE) were calculated as a measure of bias and imprecision, respectively. A PopPK model with parallel linear and non-linear elimination best fitted the data. The median and 95% confidence interval (CI) for the model parameters drug clearance (CL), volume of central compartment (V), volume of peripheral compartment (Vp) and intercompartmental clearance (Q) were 9 (7.69-11) L/h, 6.18 (4.93-11.2) L, 11.17 (7.26-12) L and 15.61 (12.66-23.8) L/h, respectively. The Michaelis-Menten constant (Km) and the maximum elimination rate for Michaelis-Menten elimination (Vmax) were estimated without population variability in the model to avoid overfitting and inflation of the type I error rate. The population estimates for Km and Vmax were 37.09 mg/L and 353.57 mg/h, respectively. The bias (ME) was -20.8 (95% CI -26.2 to -15.4) mg/L, whilst imprecision (RMSE) was 49.2 (95% CI 41.2-56) mg/L. In conclusion, piperacillin elimination is (partially) saturable. Moreover, the population estimate for Km lies within the therapeutic window and therefore saturation of elimination should be accounted for when defining optimum dosing regimens for piperacillin in critically ill patients.

Hepatotoxicidad grave por amiodarona intravenosa / Severe liver toxicity by intravenous amiodarone

No disponible

Population pharmacokinetics of piperacillin in febrile children receiving cancer chemotherapy: the impact of body weight and target on an optimal dosing regimen.

BACKGROUND: The ß-lactam antibiotic piperacillin (in combination with tazobactam) is commonly chosen for empirical treatment of suspected bacterial infections. However, pharmacokinetic variability among patient populations and across ages leads to uncertainty when selecting a dosing regimen to achieve an appropriate pharmacodynamic target. OBJECTIVES: To guide dosing by establishing a population pharmacokinetic model for unbound piperacillin in febrile children receiving cancer chemotherapy, and to assess pharmacokinetic/pharmacodynamic target attainment (100% fT > 1×MIC and 50% fT > 4×MIC) and resultant exposure, across body weights. METHODS: Forty-three children admitted for 89 febrile episodes contributed 482 samples to the pharmacokinetic analysis. The typical doses required for target attainment were compared for various dosing regimens, in particular prolonged infusions, across MICs and body weights. RESULTS: A two-compartment model with inter-fever-episode variability in CL, and body weight included through allometry, described the data. A high CL of 15.4 L/h (70 kg) combined with high glomerular filtration rate (GFR) values indicated rapid elimination and hyperfiltration. The target of 50% fT > 4×MIC was achieved for an MIC of 4.0 mg/L in a typical patient with extended infusions of 2-3 (q6h) or 3-4 (q8h) h, at or below the standard adult dose (75 and 100 mg/kg/dose for q6h and q8h, respectively). Higher doses or continuous infusion were needed to achieve 100% fT > 1×MIC due to the rapid piperacillin elimination. CONCLUSIONS: The licensed dose for children with febrile neutropenia (80 mg/kg q6h as a 30 min infusion) performs poorly for attainment of fT>MIC pharmacokinetic/pharmacodynamic targets. Given the population pharmacokinetic profile, feasible dosing regimens with reasonable exposure are continuous infusion (100% fT > 1×MIC) or prolonged infusions (50% fT > 4×MIC).

Gram-negative Bacteremia in Children With Hematologic Malignancies and Following Hematopoietic Stem Cell Transplantation: Epidemiology, Resistance, and Outcome.

Gram-negative rod (GNR) infections adversely affect the outcome of patients with malignancies and following hematopoietic stem cell transplantation (HSCT). This retrospective observational study aimed to describe the epidemiology, outcome, and resistance patterns of GNR bacteremia in children with hematologic malignancies (HM) and after HSCT during the period spanning from 2010 to 2014 in a tertiary children's hospital. A total of 270 children were included in the analysis; 65 (24%) developed 85 episodes of GNR bacteremia; the rate was 36/122 (29.5%) in post-HSCT and 29/178 (16.3%) in HM patients (P<0.05). Overall, 10% of the GNRs were carbapenem resistant. In multivariate analysis, prolonged neutropenia (≥7 d; odds ratio: 19.5, 95% confidence interval: 2.6-148.4) and total hospitalization for a duration of >30 days in the last 3 months (odds ratio: 17.5, 95% confidence interval: 1.4-224.4) were associated with carbapenem-resistant GNR bacteremia. Thirty-day mortality following GNR bacteremia was 0% in HM and 7/52 episodes (13.5%) in HSCT patients (P<0.05). Carbapenem-resistant versus carbapenem-sensitive bacteremia was associated with longer duration of bacteremia (mean: 3.8 vs. 1.7 d), higher risk for intensive care unit hospitalization (44.4% vs. 10.1%), and higher mortality rate (33% vs. 5.8%) (P<0.05). To summarize, GNR bacteremia was frequent, especially in post-HSCT children. Carbapenem resistance adversely affects patients' outcome, increasing morbidity and mortality. Empirical antibiotic therapy must be adjusted to the local resistance patterns.

Incidence of acute kidney injury among pediatric hematology/oncology patients receiving vancomycin in combination with piperacillin/tazobactam or cefepime.

There is mounting evidence that combination of antibiotic therapy with vancomycin and piperacillin/tazobactam (pip/tazo) is associated with acute kidney injury (AKI). To determine whether vancomycin plus pip/tazo is associated with higher rates of AKI compared to vancomycin plus cefepime among pediatric hematology/oncology (heme/onc) patients, we examined 121 heme/onc patients receiving at least two consecutive days of therapy with vancomycin and either pip/tazo or cefepime. Rate of AKI was higher in the pip/tazo than the cefepime group (4/27 [14.8%] vs 2/94 [2.1%], P = 0.022).

Piperacillin pharmacokinetics and target attainment in children with cancer and fever: Can we optimize our dosing strategy?

BACKGROUND: Data on piperacillin-tazobactam pharmacokinetics and optimal dosing in children with cancer and fever are limited. Our objective was to investigate piperacillin pharmacokinetics and the probability of target attainment (PTA) with standard intermittent administration (IA), and to simulate PTA in other dosing regimens. PROCEDURE: This prospective pharmacokinetic study was conducted from April 2016 to January 2018. Children with cancer receiving empiric piperacillin-tazobactam to treat infections were included. Piperacillin-tazobactam 100 mg/kg was infused over 5 min every 8 hours (IA). An optimized sample schedule provided six blood samples per subject for piperacillin concentration determination. The evaluated targets included: (1) 100% time of free piperacillin concentration above the minimum inhibitory concentration (fT > MIC) and (2) 50% fT > 4× MIC. MIC50 and MIC90 were defined based on an intrainstitutional MIC range. RESULTS: A total of 482 piperacillin concentrations were obtained from 43 children (aged 1-18 years) during 89 fever episodes. Standard IA resulted in insufficient target attainment, with significant differences in piperacillin pharmacokinetics for different body weights. Median fT > MIC was 61.2%, 53.5%, and 36.3% for MIC50 (2.0 mg/L), MIC90 (4.0 mg/L), and breakpoint for Pseudomonas aeruginosa (16.0 mg/L), respectively. Correspondingly, the median fT > 4× MIC was 43%, 36.3%, and 20.1%. Simulations showed that only continuous infusion reached a PTA of 95% for MIC = 16.0 mg/L, while extended infusion lasting half of the dosing interval reached a PTA of 95% for MIC ≤ 8 mg/L. CONCLUSIONS: Our data revealed insufficient PTA with standard IA of piperacillin-tazobactam in children with cancer and fever. Alternative dosing strategies, preferably continuous infusion, are required to ensure adequate PTA.

Extended Infusion of ß-Lactams for Bloodstream Infection in Patients With Liver Cirrhosis: An Observational Multicenter Study.

BACKGROUND: We analyzed the impact of continuous/extended infusion (C/EI) vs intermittent infusion of piperacillin-tazobactam (TZP) and carbapenems on 30-day mortality of patients with liver cirrhosis and bloodstream infection (BSI). METHODS: The BICRHOME study was a prospective, multicenter study that enrolled 312 cirrhotic patients with BSI. In this secondary analysis, we selected patients receiving TZP or carbapenems as adequate empirical treatment. The 30-day mortality of patients receiving C/EI or intermittent infusion of TZP or carbapenems was assessed with Kaplan-Meier curves, Cox-regression model, and estimation of the average treatment effect (ATE) using propensity score matching. RESULTS: Overall, 119 patients received TZP or carbapenems as empirical treatment. Patients who received C/EI had a significantly lower mortality rate (16% vs 36%, P = .047). In a Cox-regression model, the administration of C/EI was associated with a significantly lower mortality (hazard ratio [HR], 0.41; 95% confidence interval [CI], 0.11-0.936; P = .04) when adjusted for severity of illness and an ATE of 25.6% reduction in 30-day mortality risk (95% CI, 18.9-32.3; P < .0001) estimated with propensity score matching. A significant reduction in 30-day mortality was also observed in the subgroups of patients with sepsis (HR, 0.21; 95% CI, 0.06-0.74), acute-on-chronic liver failure (HR, 0.29; 95% CI, 0.03-0.99), and a model for end-stage liver disease score ≥25 (HR, 0.26; 95% CI, 0.08-0.92). At competing risk analysis, C/EI of beta-lactams was associated with significantly higher rates of hospital discharge (subdistribution hazard [95% CI], 1.62 [1.06-2.47]). CONCLUSIONS: C/EI of beta-lactams in cirrhotic patients with BSI may improve outcomes and facilitate earlier discharge.

Intramedullary Antibiotic Delivery for Emphysematous Osteomyelitis of the Femur.

The authors present a case of bilateral femoral emphysematous osteomyelitis caused by Escherichia coli in a 60-year-old woman with rheumatoid arthritis who was receiving long-term prednisone therapy. The infection in both femoral shafts was eradicated with surgical debridement, followed by insertion of intramedullary rods composed of culture-specific antibiotic cement into the femoral canals in conjunction with 6 weeks of intravenous antibiotics. The rods were subsequently removed, and no signs of further osteomyelitis were recognized at follow-up. To the authors' knowledge, this is the first case of its kind reported in the orthopedic literature. Emphysematous osteomyelitis, a rare and dangerous entity, can be successfully managed by intramedullary antibiotic delivery in the subacute setting. [Orthopedics. 2019; 42(1):e128-e130.].

Optimal Piperacillin-Tazobactam Dosing Strategies against Extended-Spectrum-ß-Lactamase-Producing Enterobacteriaceae.

Piperacillin-tazobactam has been proposed as an alternative to carbapenems for the treatment of infections caused by extended-spectrum-ß-lactamase (ESBL)-producing Enterobacteriaceae However, limited understanding of optimal dosing strategies for this combination may curtail its utility. In this study, we correlated various exposures of piperacillin-tazobactam to efficacy, using a modified pharmacokinetic/pharmacodynamic index. Using a clinical Klebsiella pneumoniae isolate expressing CTX-M-15, piperacillin MIC values were determined with increasing tazobactam concentrations and fitted to a sigmoid inhibitory maximum effect (Emax) model. A hollow-fiber infection model (HFIM) was used to evaluate the efficacy of escalating tazobactam dosing with a fixed piperacillin exposure. Simulated drug concentrations from the HFIM were incorporated in the Emax model to determine the percentage of free time above instantaneous MIC (%fT>MICi) associated with each experimental exposure. The target %fT>MICi associated with growth suppression was prospectively validated using an SHV-12-producing isolate of Escherichia coli and 2 other CTX-M-15-producing K. pneumoniae isolates. Based on our reference isolate, piperacillin-tazobactam exposures of %fT>MICi of ≥55.1% were associated with growth suppression. Despite underlying differences, these findings were consistent with prospective observations in 3 other clinical isolates. Our modeling approach can be applied relatively easily in the clinical setting, and it appeared to be robust in predicting the effectiveness of various piperacillin-tazobactam exposures. This modified pharmacokinetic/pharmacodynamic index could be used to characterize response to other ß-lactam/ß-lactamase inhibitor combinations.

The addition of avibactam renders piperacillin an effective treatment for Mycobacterium abscessus infection in an in vivo model.

Treating M. abscessus infection is challenging due to the potent ß-lactamase BlaMab (Beta-lactamase of M. abscessus). Avibactam is a non-ß-lactam, ß-lactamase inhibitor shown to inhibit BlaMab. We tested whether avibactem can render piperacillin effective against M. Abscessus. In-vitro, avibactam enhanced the activity of piperacillin by 16-32 fold, with no significant effect on meropenem. In an in-vivo Galleria mellonella model, meropenem and piperacillin/avibactam significantly decreased infection burden compared to untreated controls. Neither piperacillin nor avibactam alone had a significant effect.