Ertapenem: a review of its use in the treatment of bacterial infections

Progress in the Stereoselective Synthesis Methods of Pyrrolidine-Containing Drugs and Their Precursors

The presented review systematizes and summarizes the data on the synthesis of pyrrolidine derivatives, which are precursors for obtaining drugs. Based on the analysis of published data, the most promising directions in the synthesis of biologically active compounds containing a pyrrolidine ring are identified. Stereoselective synthesis methods are classified based on the source of the pyrrolidine ring. The first group includes methods that use a pyrrolidine ring as the starting compound. The second group combines stereoselective methods of cyclization of acyclic starting compounds, which lead to optically pure pyrrolidine derivatives.

A Comprehensive Overview of the Antibiotics Approved in the Last Two Decades: Retrospects and Prospects

Due to the overuse of antibiotics, bacterial resistance has markedly increased to become a global problem and a major threat to human health. Fortunately, in recent years, various new antibiotics have been developed through both improvements to traditional antibiotics and the discovery of antibiotics with novel mechanisms with the aim of addressing the decrease in the efficacy of traditional antibiotics. This manuscript reviews the antibiotics that have been approved for marketing in the last 20 years with an emphasis on the antibacterial properties, mechanisms, structure-activity relationships (SARs), and clinical safety of these antibiotics. Furthermore, the current deficiencies, opportunities for improvement, and prospects of antibiotics are thoroughly discussed to provide new insights for the design and development of safer and more potent antibiotics.

Drug-induced tooth discoloration: An analysis of the US food and drug administration adverse event reporting system

Background: Certain drugs can cause intrinsic or extrinsic tooth discoloration, which is not only a clinical issue but also an esthetic problem. However, limited investigations have focused on drug-induced tooth discoloration. The present work aimed to determine the drugs causing tooth discoloration and to estimate their risks of causing tooth discoloration. Methods: An observational, retrospective, and pharmacovigilance analysis was conducted, in which we extracted adverse event (AE) reports involving tooth discoloration by using the data of the US Food and Drug Administration's Adverse Event Reporting System (FAERS) from the first quarter (Q1) of 2004 to the third quarter (Q3) of 2021. Disproportionality analyses were performed to examine risk signals for tooth discoloration and determine the drugs inducing tooth discoloration. Results: Based on predefined inclusion criteria, 1188 AE reports involving 302 suspected drugs were identified. After data mining, 25 drugs generated positive risk signals for tooth discoloration, of which 10 were anti-infectives for systemic use. The top reported drug was tetracycline (n = 106), followed by salmeterol and fluticasone (n = 68), amoxicillin (n = 60), chlorhexidine (n = 54), and nicotine (n = 52). Cetylpyridinium (PRR = 472.2, ROR = 502.5), tetracycline (PRR = 220.4, ROR = 277), stannous fluoride (PRR = 254.3, ROR = 262.8), hydrogen peroxide (PRR = 240.0, ROR = 247.6), and chlorhexidine (PRR = 107.0, ROR = 108.4) showed stronger associations with tooth discoloration than the remaining drugs. Of 625 AE reports involving 25 drugs with positive risk signals, tooth discoloration was mostly reported in patients aged 45-64 (n = 110) and ≤18 (n = 95), and 29.4% (192/652) of the reports recorded serious outcomes. Conclusion: This study revealed that certain drugs are significantly associated with tooth discoloration. Caution should be exercised when using these drugs, especially during pregnancy and early childhood.

Effectiveness of ertapenem for treatment of infections in children: An evidence mapping and meta-analysis

OBJECTIVES

To assess and summarize current evidence on the effectiveness and safety of ertapenem for treatment of childhood infections, in consideration of high infection prevalence in children and wide use of ertapenem.

METHODS

The following 8 databases were searched on 13th May 2021: Web of Science, Embase via Ovid SP, PubMed, The Cochrane Library (CENTRAL), Chinese BioMedical Literature Database (CBM), China National Knowledge Infrastructure (CNKI), VIP and Wanfang. The primary outcome was treatment success rate. Risk ratios (RRs) and 95% confidence interval (CI) were estimated using random-effect models. Subgroup analysis was conducted where heterogeneity was found.

RESULTS

Fifteen studies (8 randomized controlled trials, 1 observational comparative study, and 6 before and after studies) involving 2,528 patients were included in the final review. Ertapenem had similar treatment success rates with β-lactam antibiotics [relative risk (RR) = 1.08, 95% CI: 0.99-1.19]. In a subgroup analysis, similar efficacy (RR = 1.08, 95% CI: 0.97-1.20) between ertapenem and other carbapenems. Compared with β-lactam antibiotics, ertapenem did not increase the risk of any adverse events (RR = 1.02, 95%CI: 0.71-1.48), drug-related diarrhea (all non-Asian children, RR = 0.62, 95%CI: 0.31-1.25), or injection site pain (all non-Asian children, RR = 1.66, 95%CI: 0.59-4.68). Subgroup analysis showed no obvious difference between ertapenem group and carbapenems or non-carbapenems group on risk of adverse events.

CONCLUSION

Our findings suggest that ertapenem is effective and safe in treatment for children with infection. Further comparative real-world data is needed to supplement clinical evidence on the overall benefits of ertapenem in this population.

Safety of Intravenous Push Ertapenem Compared to Intravenous Piggyback at a Tertiary Academic Medical Center

Background: Recent shortages of intravenous (IV) fluids have resulted in healthcare systems converting administration of many medications from IV piggyback (IVPB) to IV push (IVP). Administering medications via IVP presents numerous advantages; however, IV site reactions such as phlebitis and infiltration may occur. Objective: The objective of this analysis is to evaluate the infusion site safety of ertapenem given as peripheral IVP compared to IVPB in adult patients. Methods: This was an institutional review board-approved, single-center, retrospective study. Patients, ages 18 or older, receiving IV ertapenem were identified. The major endpoints analyzed were IV site reactions including phlebitis and infiltration. The Naranjo Nomogram was utilized to assess the causality of the reactions to determine the likelihood of whether the event was caused by the medication itself or other factors. Results: To date, 283 administrations (92 patients) in the IVP group and 319 administrations (82 patients) in the IVPB group were analyzed. There were 13 IV site reactions compared to 8 in the IVP vs IVPB group, respectively (P-value = 0.16). Ten of the events in the IVP group were deemed "possible" and 2 deemed "doubtful," while the remaining event was considered "probable" per the Naranjo Nomogram. Of the events in the IVPB group, all 8 were found to be "possible." Conclusion: The administration of IVP ertapenem showed comparable rates of infusion site reactions compared to IVPB. Implementation of IVP ertapenem appears to be associated with infusion site safety similar to IVPB and should be considered safe to administer.

Whole Genome Sequencing of a Citrobacter freundii Strain Isolated from the Hospital Environment: An Extremely Multiresistant NDM-1 and VIM-48 Coproducing Isolate

Citrobacter freundii has acquired resistance to several antimicrobial drugs, including last-resort antibiotics affecting, therefore, clinical efficacy and causing high rates of mortality. In this study, we investigate the whole genome sequence of a carbapenem-resistant C. freundii strain isolated from the hospital environment in Tunisia. A total of 210 samples were taken using sterile swabs, from inanimate surfaces, medical devices, and care staff, during the period extended between March and April 2019. After the microbiological analysis of samples and antimicrobial susceptibility testing, only one strain identified as C. freundii showing resistance to carbapenems was selected for the whole genome sequencing. The genome analysis revealed a high-level resistance to most antibiotics. Interestingly, we have noted the coexistence of bla_NDM-1 and bla_VIM-48 metallo-β-lactamase (MBL) encoding genes conferring resistance to carbapenems. Other β-lactamases encoding genes have also been detected, including bla_TEM-1, bla_CMY-48, and bla_OXA-1. Moreover, genes conferring resistance to aminoglycoside [aac(3)-IId, ant(3″)-Ia, aadA, aac(6')-Ib], macrolide [mph(A)], sulfonamide (sul1), trimethoprim (dfrA1), tetracycline [tet(D)], chloramphenicol [cat(B3)], rifamycin (arr-3), and quinolone (qnrB) have been revealed. The multi-locus sequence typing analysis showed that this isolate could not be assigned to an existing sequence type (ST), but it is almost identical to ST22. The plasmid investigation revealed the presence of five plasmids belonging to diverse incompatibility groups (IncFII, IncHI1A, IncHI1B, IncN, and IncX3). To the best of our knowledge, our findings report the first detection of NDM-1 and VIM-48 coproducing C. freundii in Tunisia and the second detection in the world of the bla_VIM-48.

Chemical Classes Presenting Novel Antituberculosis Agents Currently in Different Phases of Drug Development: A 2010-2020 Review

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is a curable airborne disease currently treated using a drug regimen consisting of four drugs. Global TB control has been a persistent challenge for many decades due to the emergence of drug-resistant Mtb strains. The duration and complexity of TB treatment are the main issues leading to treatment failures. Other challenges faced by currently deployed TB regimens include drug-drug interactions, miss-matched pharmacokinetics parameters of drugs in a regimen, and lack of activity against slow replicating sub-population. These challenges underpin the continuous search for novel TB drugs and treatment regimens. This review summarizes new TB drugs/drug candidates under development with emphasis on their chemical classes, biological targets, mode of resistance generation, and pharmacokinetic properties. As effective TB treatment requires a combination of drugs, the issue of drug-drug interaction is, therefore, of great concern; herein, we have compiled drug-drug interaction reports, as well as efficacy reports for drug combinations studies involving antitubercular agents in clinical development.

Treatment Strategies Against Diabetic Foot Ulcer: Success so Far and the Road Ahead

BACKGROUND

Diabetic foot ulcer (DFU) is one of the leading complications of type-2 diabetes mellitus. It is associated with neuropathy and peripheral arterial disease of the lower limb in patients with diabetes. There are four stages of wound healing, namely hemostasis phase, inflammatory phase, proliferative phase and maturation phase. In the case of DFU, all these stages are disturbed which lead to delay in healing and consequently to lower limb amputation. Conventional dosage forms like tablets, creams, ointments, gels and capsules have been used for the treatment of diabetic foot ulcer for many years.

INTRODUCTION

In this review, the global prevalence as well as etiopathogenesis related to diabetic foot ulcer have been discussed. The potential role of various synthetic and herbal drugs, as well as their conventional dosage forms in the effective management of DFU have been discussed in detail.

METHODS

Structured search of bibliographic databases from previously published peer-reviewed research papers was explored and data has been represented in terms of various approaches that are used for the treatment of DFU.

RESULTS

About 148 papers, including both research and review articles, were included in this review to produce a comprehensive as well as a readily understandable article. A series of herbal and synthetic drugs have been discussed along with their current status of treatment in terms of dose and mechanism of action.

CONCLUSION

DFU has become one of the most common complications in patients having diabetes for more than ten years. Hence, understanding the root cause and its successful treatment is a big challenge because it depends upon multiple factors such as the judicious selection of drugs as well as proper control of blood sugar level. Most of the drugs that have been used so far either belong to the category of antibiotics, antihyperglycaemic or they have been repositioned. In clinical practice, much focus has been given to dressings that have been used to cover the ulcer. The complete treatment of DFU is still a farfetched dream to be achieved and it is expected that combination therapy of herbal and synthetic drugs with multiple treatment pathways could be able to offer better management of DFU.

A case series of confusional states and other neurotoxic effects caused by ertapenem

Ten cases of ertapenem neurotoxicity, mainly confusional states, are described, some of them with fatal outcomes. The majority of patients (90%) had a creatinine clearance (CrCl) < 50 mL/min/1.73m² at some point during treatment and hypoalbuminaemia was always present when ertapenem treatment was started. The pharmacokinetic and pharmacodynamic properties of this carbapenem could favour a different profile, and approved doses can be excessive in some patients with moderate renal failure (CrCl 31-59 mL/min/1.73 m² ). It may be necessary to re-evaluate renal function during treatment and adjust doses or reconsider the adequacy of treatment based on clinical judgement, especially if relevant changes in the CrCl occur (i.e. a reduction to ≤30 mL/min/1.73 m² ) or unexplained behavioural disorders are detected. The onset of the symptoms of ertapenem neurotoxicity can be insidious and go unnoticed, and so a knowledge and early suspicion of confusional states are important to improve the patient prognosis.

A Physiologically Based Pharmacokinetic Model of Ertapenem in Pediatric Patients With Renal Impairment

Ertapenem is a widely used antibiotic; however, its pharmacokinetics has not been fully evaluated in children with renal impairment. A physiologically based pharmacokinetic (PBPK) model of ertapenem was established and validated to simulate its disposition in the healthy population and adults with renal impairment, as well as to predict the exposure in pediatric patients with renal impairment. The simulated PBPK modeling results and the observed data of ertapenem after intravenous administration of various regimens were consistent according to the fold error values of less than 2. Furthermore, %T > MIC of ertapenem was evaluated using the PBPK model. The C_max was not significantly changed in pediatric patients with renal impairment compared to healthy children. However, the AUC was 1.42-fold, 1.84-fold, 2.37-fold, and 3.52-fold higher in mild, moderate, severe renal impairment, and end-stage renal disease, respectively, than that in healthy children and the doses of ertapenem were reduced to 13 mg/kg b.i.d, 9 mg/kg b.i.d, 6 mg/kg b.i.d, and 5 mg/kg b.i.d, respectively. The probability of achieving 40%T > MIC (MIC ≤ 4 μg/mL) was nearly 100% throughout the recommended dosing interval. In conclusion, our model can be used as a tool to generate better predictions for the most effective ertapenem dosing in pediatric patients.

Microbial Natural Products in Drug Discovery

Over a long period of time, humans have explored many natural resources looking for remedies of various ailments. Traditional medicines have played an intrinsic role in human life for thousands of years, with people depending on medicinal plants and their products as dietary supplements as well as using them therapeutically for treatment of chronic disorders, such as cancer, malaria, diabetes, arthritis, inflammation, and liver and cardiac disorders. However, plant resources are not sufficient for treatment of recently emerging diseases. In addition, the seasonal availability and other political factors put constrains on some rare plant species. The actual breakthrough in drug discovery came concurrently with the discovery of penicillin from Penicillium notatum in 1929. This discovery dramatically changed the research of natural products and positioned microbial natural products as one of the most important clues in drug discovery due to availability, variability, great biodiversity, unique structures, and the bioactivities produced. The number of commercially available therapeutically active compounds from microbial sources to date exceeds those discovered from other sources. In this review, we introduce a short history of microbial drug discovery as well as certain features and recent research approaches, specifying the microbial origin, their featured molecules, and the diversity of the producing species. Moreover, we discuss some bioactivities as well as new approaches and trends in research in this field.

Moxifloxacin in Pediatric Patients With Complicated Intra-abdominal Infections: Results of the MOXIPEDIA Randomized Controlled Study

BACKGROUND

This study was designed to evaluate primarily the safety and also the efficacy of moxifloxacin (MXF) in children with complicated intra-abdominal infections (cIAIs).

METHODS

In this multicenter, randomized, double-blind, controlled study, 451 pediatric patients aged 3 months to 17 years with cIAIs were treated with intravenous/oral MXF (N = 301) or comparator (COMP, intravenous ertapenem followed by oral amoxicillin/clavulanate; N = 150) for 5 to 14 days. Doses of MXF were selected based on the results of a Phase 1 study in pediatric patients (NCT01049022). The primary endpoint was safety, with particular focus on cardiac and musculoskeletal safety; clinical and bacteriologic efficacy at test of cure was also investigated.

RESULTS

The proportion of patients with adverse events (AEs) was comparable between the 2 treatment arms (MXF: 58.1% and COMP: 54.7%). The incidence of drug-related AEs was higher in the MXF arm than in the COMP arm (14.3% and 6.7%, respectively). No cases of QTc interval prolongation-related morbidity or mortality were observed. The proportion of patients with musculoskeletal AEs was comparable between treatment arms; no drug-related events were reported. Clinical cure rates were 84.6% and 95.5% in the MXF and COMP arms, respectively, in patients with confirmed pathogen(s) at baseline.

CONCLUSIONS

MXF treatment was well tolerated in children with cIAIs. However, a lower clinical cure rate was observed with MXF treatment compared with COMP. This study does not support a recommendation of MXF for children with cIAIs when alternative more efficacious antibiotics with better safety profile are available.

Risk factors associated with the development of seizures among adult patients treated with ertapenem: A matched case-control study

Objective

The purpose of this study is to compare the characteristics of those ertapenem-treated adult patients with and without development of seizures, and identify the associated factors for the development of seizures.

Methods

This retrospective study was conducted at Chia-Yi Christian Hospital from January 2012 to December 2014. Patients developing seizures during their ertapenem treatment course were identified as case patients. Those without seizures who had received ertapenem for at least five days were considered as the pool of control patients. For each case patient, four matched patients from the control pool were randomly selected as the final control group, based on age, gender, and the date of ertapenem prescription.

Results

A total of 1706 ertapenem-treated patients were identified, 33 (1.9%) individuals developed seizures with the enrollment of 132 matched control patients. Among these 33 patients, the average age was 79.3 ± 7.5 years, and 20 (60.6%) were male. The mean Charlson co-morbidity score was 4.5 ± 2.4, and the first episode of seizure happened 3.3 ± 2.6 days after receiving ertapenem. In multivariate logistic regression analysis, the independent predictors associated with the development of ertapenem-associated seizures were old stroke (OR, 14.36; 95% CI, 4.38–47.02; p < 0.0001), undergoing brain images within one year prior to the admission (OR, 5.73; 95% CI, 1.78–18.43; p = 0.0034), low hemoglobin level (OR, 3.88; 95% CI, 1.28–12.75; p = 0.0165) and low platelet count (OR, 4,94; 95% CI, 1.56–15.68; p = 0.0067) at presentations, and protective factors against the development of seizures were heart failure (OR, 0.04; 95% CI, 0.00–0.63; p = 0.0222), concomitant use of steroids (OR, 0.19; 95% CI, 0.05–0.77; p = 0.0201), or antiplatelet agents (OR, 0.12; 95% CI, 0.02–0.63, p = 0.0123) with ertapenem.

Conclusions

The development of ertapenem-associated seizures may occur more frequently and much earlier due to its widespread use in treating drug-resistant pathogens, especially when these pathogens emerged worldwide.Our study would help physician to estimate the risk of developing seizure among patients receiving ertapenem.

An update on emerging therapies for urinary tract infections

INTRODUCTION

Urinary tract infections (UTIs) are the most common healthcare-acquired infections, and are associated with high morbidity and mortality. Worldwide use of antibiotics has led to a significant rise in resistant uropathogens emanating from both hospitals and communities. The huge concern of multidrug resistance (MDR) has led the Food and Drug Administration (FDA) to encourage drug companies to invest in the development of new antibiotics. Area covered: In this review we summarized data on already approved antibiotics, and selected emerging therapies that are currently in phase II and III trials with emphasis on complicated urinary tract infections (cUTIs). We performed our search using PubMed, ClinicalTrials.gov, Google Scholar and Pharmaprojects. Expert opinion: Efficacious antimicrobials are needed to overcome MDR organisms. There are several dugs in initial and later stages of development, but most of them lack full spectrum of activity against some Gram-negative organisms, particularly against MDR Pseudomonas aeruginosa. Better understanding of the pathogenesis of UTI and genetic engineering of pathogens can provide new drugs to combat resistance in the future.

Population Pharmacokinetics and Target Attainment of Ertapenem in Plasma and Tissue Assessed via Microdialysis in Morbidly Obese Patients after Laparoscopic Visceral Surgery

Ertapenem provides broad-spectrum activity against many pathogens, and its use is relevant for the prophylaxis and treatment of infections in morbidly obese patients undergoing surgery. However, its pharmacokinetics and tissue penetration in these patients are not well defined. We assessed the population pharmacokinetics and target attainment for ertapenem in the plasma, subcutaneous tissue, and peritoneal fluid of morbidly obese patients. Six female patients (body mass index, 43.7 to 55.9 kg/m²) received 1,000 mg ertapenem as 15-min infusions at 0 and 26 h. On day 2, the unbound ertapenem concentrations in plasma, subcutaneous tissue, and peritoneal fluid were measured by microdialysis; total plasma concentrations were additionally quantified. The probability of attaining a target of an unbound ertapenem concentration above the MIC for at least 40% of the dosing interval was predicted via Monte Carlo simulations. The population pharmacokinetic model contained two disposition compartments and simultaneously described all concentrations. For unbound ertapenem, total clearance was 12.3 liters/h (coefficient of variation, 21.6% for between-patient variability) and the volume of distribution at steady state was 57.8 liters in patients with a 53-kg fat-free mass. The area under the concentration-time curve (AUC) for ertapenem was 49% lower in subcutaneous tissue and 25% lower in peritoneal fluid than the unbound AUC in plasma. Tissue penetration was rapid (equilibration half-life, <15 min) and was variable in subcutaneous tissue. Short-term ertapenem infusions (1,000 mg every 24 h) achieved robust (>90%) target attainment probabilities for MICs of up to 1 mg/liter in plasma, 0.25 to 0.5 mg/liter in subcutaneous tissue, and 0.5 mg/liter in peritoneal fluid. Ertapenem presents an attractive choice for many pathogens relevant to morbidly obese patients undergoing surgery. (This study has been registered at ClinicalTrials.gov under identifier NCT01407965.).

Treatment efficacy and superinfection rates in complicated urinarytract infections treated with ertapenem or piperacillin tazobactam

BACKGROUND/AIM

In this retrospective study, the efficacy of ertapenem and piperacillin tazobactam was compared in the treatment of complicated urinary tract infections (cUTIs). Treatment responses were also evaluated for both antibiotics.

MATERIALS AND METHODS

A total of 230 patients were enrolled in the study. Of these, 170 received ertapenem and 60 received piperacillin-tazobactam.

RESULTS

In both groups, urine cultures after 48 h were negative for the initial uropathogen. The frequency of superinfection was 29.4% in the ertapenem group and 8.3% in the piperacillin-tazobactam group over the duration of treatment (P < 0.05). Urinary catheterization increased the superinfection risk 2.88-fold in the ertapenem group and diabetes mellitus increased the risk 8.50-fold in the piperacillin-tazobactam group (CI: 1.44-5.76 and 1.16-62.09, respectively, P < 0.05). The main pathogen isolated from superinfection in the ertapenem group after 48 h was Enterococcus spp. (71.4%).

CONCLUSION

Both ertapenem and piperacillin-tazobactam were effective in the treatment of cUTIs caused by ESBL-producing microorganisms. A high frequency of superinfection in the ertapenem group was the result of Enterococcus and Pseudomonas spp., against which ertapenem is not active. In the presence of urinary catheterization, diabetes mellitus, and urological intervention, patients should be closely monitored for the development of a superinfection, especially patients receiving ertapenem.

Huang J, Cooper MA, Li J, Velkov T. The Plasma Protein Binding Proteome of Ertapenem: A Novel Compound-Centric Proteomic Approach for Elucidating Drug-Plasma Protein Binding Interactions

Ertapenem is an important first-line carbapenem antibiotic used for the treatment of aerobic Gram-negative bacterial infections. It is the only marketed carbapenem that is highly bound to plasma proteins and displays a concentration-dependent and saturable plasma protein binding profile. To date, the plasma components responsible for sequestering ertapenems antibacterial activity remain uncharacterized. In the present study, we have employed an orthogonal, multiplatform approach, including novel compound-centric displacement proteomics and surface plasmon resonance to characterize the plasma protein binding proteome of ertapenem. In proof-of-concept, the capacity of physiological cocktails of the identified plasma proteins to inhibit the antibacterial activity of ertapenem was assessed with in vitro microbiological assays. We show that fibrinogen, complement C4, haptoglobulin, α-1-antitrypsin, fibronectin, transferrin, immunoglobulin G, hemopexin, and humans serum albumin are responsible for the majority of the sequestering activity in plasma. No binding was observed to α-1-acid-glycoprotein. The findings of this study have broad reaching implications for antibiotic drug design and for dose tailoring to suit the plasma protein levels of individual patients in order to maximize the clinical efficacy of important first-line antibiotics such as ertapenem.

The Clinical Efficacy and Safety of Ertapenem for the Treatment of Complicated Urinary Tract Infections Caused by ESBL-Producing Bacteria in Children

Background. Urinary tract infections (UTIs) are common and important clinical problem in childhood, and extended-spectrum-beta-lactamase- (ESBL-) producing organisms are the leading cause of healthcare-related UTIs. In this study, we aimed to evaluate the clinical efficacy and safety of ertapenem therapy in children with complicated UTIs caused by ESBL-producing organisms. Methods. Seventy-seven children with complicated UTIs caused by ESBL-producing organisms were included in this retrospective study, and all had been treated with ertapenem between January 2013 and June 2014. Results. Sixty-one (79%) females and sixteen (21%) males with a mean ± standard deviation (SD) age of 76.6 ± 52 months (range 3–204, median 72 months) were enrolled in this study. Escherichia coli (E. coli) (n = 67; 87%) was the most common bacterial cause of the UTIs followed by Klebsiella pneumoniae (K. pneumoniae) (n = 9; 11.7%) and Enterobacter cloacae (E. cloacae) (n = 1; 1.3%). The mean duration of the ertapenem therapy was 8.9 ± 1.6 days (range 4–11). No serious drug-related clinical or laboratory adverse effects were observed, and the ertapenem therapy was found to be safe and well tolerated in the children in our study. Conclusion. Ertapenem is a newer carbapenem with the advantage of once-daily dosing and is highly effective for treating UTIs caused by ESBL-producing microorganisms.

Antianaerobic antimicrobials: spectrum and susceptibility testing

Susceptibility testing of anaerobic bacteria recovered from selected cases can influence the choice of antimicrobial therapy. The Clinical and Laboratory Standards Institute (CLSI) has standardized many laboratory procedures, including anaerobic susceptibility testing (AST), and has published documents for AST. The standardization of testing methods by the CLSI allows comparisons of resistance trends among various laboratories. Susceptibility testing should be performed on organisms recovered from sterile body sites, those that are isolated in pure culture, or those that are clinically important and have variable or unique susceptibility patterns. Organisms that should be considered for individual isolate testing include highly virulent pathogens for which susceptibility cannot be predicted, such as Bacteroides, Prevotella, Fusobacterium, and Clostridium spp.; Bilophila wadsworthia; and Sutterella wadsworthensis. This review describes the current methods for AST in research and reference laboratories. These methods include the use of agar dilution, broth microdilution, Etest, and the spiral gradient endpoint system. The antimicrobials potentially effective against anaerobic bacteria include beta-lactams, combinations of beta-lactams and beta-lactamase inhibitors, metronidazole, chloramphenicol, clindamycin, macrolides, tetracyclines, and fluoroquinolones. The spectrum of efficacy, antimicrobial resistance mechanisms, and resistance patterns against these agents are described.

Carbapenems in the USA: focus on doripenem

The threat of antibacterial resistance continues to increase globally, and therapeutic options for the treatment of some serious infectious diseases are diminishing. The carbapenems are a potent class of broad-spectrum drugs, and their stability against hydrolysis by many important beta-lactamases make them an important weapon in the treatment of beta-lactamase-producing bacterial pathogens. This review focuses on four carbapenems of clinical importance in the USA: imipenem, meropenem, ertapenem and doripenem. After a historical review of carbapenem development, these four carbapenems are evaluated based on their mechanism of action, spectrum of activity, potency, pharmacodynamics, clinical pharmacokinetics, clinical profiles and toxicity issues.

Management of urinary tract infections from multidrug-resistant organisms

Antibiotic resistance worsens clinical outcomes and, in some cases, significantly impacts the clinical management of urinary tract infections in the outpatient setting. This article presents the prevalence and mechanism of relevant antimicrobial resistance patterns encountered among uropathogens, and discusses the efficacy of antibiotic regimens and novel therapies in treating commonly encountered multidrug-resistant organisms.

Clinical outcomes with ertapenem as a first-line treatment option of infections caused by extended-spectrum β-lactamase producing gram-negative bacteria

BACKGROUND

Infections caused by extended-spectrum β-lactamase (ESBL)-producing gram-negative organisms are a growing concern in hospitalized patients. Traditionally, these infections can be effectively treated by the carbapenem class of drugs. In 2005, our institution initiated a protocol for use of ertapenem, a carbapenem, as the first-line treatment option for these infections. It is unknown whether ertapenem is associated with similar clinical response and microbiologic cure rates as those achieved with group 2 carbapenems (imipenem, meropenem, doripenem).

OBJECTIVE

To describe clinical response and microbiologic cure rates associated with ertapenem as first-line treatment of infections caused by ESBL-producing organisms.

METHODS

This case series included patients who received ertapenem for more than 48 hours to treat a documented infection with a positive culture for an ESBL-producing organism. Efficacy was determined by the clinical response and microbiologic cure rates achieved with ertapenem.

RESULTS

Seventy-three patients received ertapenem for a mean (SD) of 10.7 (5.9) days. The most common (59%) infection site was urine. The most common causative organisms were ESBL-producing Klebsiella pneumoniae (47%) and Escherichia coli (48%). Clinical response was observed in 78% of patients. Microbiologic cure was achieved in 92% of the evaluable population (n = 50). There were no significant differences in clinical or microbiologic cure rates across important subgroups.

CONCLUSIONS

Patients treated with ertapenem achieved favorable clinical response and microbiologic cure rates. Our data suggest that ertapenem can be used as an alternative to group 2 carbapenems for the treatment of infections caused by ESBL-producing gram-negative organisms.

Bacterial skin and soft tissue infections: review of the epidemiology, microbiology, aetiopathogenesis and treatment: a collaboration between dermatologists and infectivologists

Bacterial skin and soft tissues infections (SSTI) often determine acute disease and frequent emergency recovering, and they are one of the most common causes of infection among groups of different ages. Given the variable presentation of SSTI, a thorough assessment of their incidence and prevalence is difficult. The presence of patient-related (local or systemic) or environmental risk factors, along with the emergence of multi-drug resistant pathogens, can promote SSTI. These infections may present with a wide spectrum of clinical features and different severity, and can be classified according to various criteria. Many bacterial species can cause SSTI, but Gram-positive bacteria are the most frequently isolated, with a predominance of Staphylococcus aureus and Streptococcus pyogenes. The diagnosis of SSTI requires an extended clinical history, a thorough physical examination and a high index of suspicion. Early diagnosis is particularly important in complicated infections, which often require laboratory studies, diagnostic imaging and surgical exploration. SSTI management should conform to the epidemiology, the aetiology, the severity and the depth of the infection. Topical, oral or systemic antimicrobial therapy and drainage or debridement could be necessary, along with treatment of a significant underlying disease. This review discusses the epidemiology, the pathogenesis and the classification of bacterial SSTI, describes their associated risk factors and their clinical presentations. The authors provide a rational diagnostic and therapeutic approach to SSTI in respect of antibiotic resistance and currently available antimicrobial agents.

Antimicrobial de-escalation strategies in hospitalized patients with pneumonia, intra-abdominal infections, and bacteremia

Increasing numbers of serious hospital/healthcare- or community-acquired infections are caused by resistant (often multi-drug resistant) bacterial pathogens. Because delayed or ineffective initial therapy can have severe negative consequences, patients at risk for these types of infections typically receive initial empiric antibiotic therapy with a broad-spectrum regimen covering the most likely pathogens, based on local surveillance data and risk factors for infection with a resistant microorganism. While improving the likelihood of a successful outcome, use of broad-spectrum, often high-dose, empiric antimicrobial therapy also creates pressure for the selection or development of resistant microorganisms, as well as increasing costs and possibly exposing patients to adverse events or collateral damage such as Clostridium difficile-associated disease. De-escalation is a strategy that attempts to balance the competing aims of providing initial empiric therapy that is appropriate and covers the likely pathogens, and limiting antimicrobial exposure and increased risk for emergence of resistant pathogens. More specifically, the de-escalation strategy involves collection of cultures for later microbiological assessment before initiating broad-spectrum empiric therapy covering the most likely pathogens, with the intention of streamlining or de-escalating to a more narrow-spectrum antimicrobial regimen 2-3 days later if warranted by clinical status and culture results. In some cases, negative culture results and subsequent clinical review may allow for termination of initial empiric therapy. In this manner, de-escalation enables more effective targeting of the causative pathogen(s), elimination of redundant therapy, a decrease in antimicrobial pressure for emergence of resistance, and cost savings. This article examines application of the de-escalation strategy to 3 case patients, one with healthcare-associated pneumonia, another with complicated intra-abdominal infection, and a third with central line-associated bacteremia.

[Empirical antibiotic therapy of complicated skin and soft tissue infections in dermatological practice]

Erysipelas is an acute bacterial infection of the skin predominantly caused by Streptococcus pyogenes. According to the international classification complicated erysipelas belongs to the complicated skin and soft tissue infections. Complicated infections are defined as severe skin involvement or when the infection occurs in compromised hosts. These infections frequently involve Gram-negative bacilli and anaerobic bacteria.

AIMS

The aim of this study was to compare the efficacy of the empirical antibiotic therapy for the patients who were admitted to the Department of Dermatology and Allergology, University of Szeged.

METHODS

The empirical therapy was started according to a previously determined protocol. The data of 158 patients with complicated skin and soft tissue infections were analyzed and the microbiology culture specimens and the isolates were also examined.

RESULTS AND CONCLUSIONS

The results show that penicillin is the first choice for the treatment of erysipelas. However, the complicated skin and soft tissue infections require broad-spectrum antibiotics.

Antimicrobial stewardship: bridging the gap between quality care and cost

PURPOSE OF REVIEW

Antibiotic resistance continues to rise, whereas development of new agents to counter it has slowed. A heightened need exists to maintain the effectiveness of currently available agents. This review focuses on the need for better antimicrobial stewardship, expected benefits of well designed antimicrobial stewardship programs (ASPs), and provides suggestions for development of an effective ASP.

RECENT FINDINGS

Healthcare-associated infections (HAIs) are a significant cause of poor treatment outcomes and elevated healthcare and societal costs worldwide. HAIs are often caused by antibiotic-resistant pathogens; overuse of antibiotics has been linked with antibiotic resistance. Benefits of improved antimicrobial stewardship include reduced emergence of antibiotic resistance, limitation of drug-related adverse events, minimization of other consequences of antibiotic use (e.g., superinfection), and reduction of societal and healthcare-related costs. In 2007, the Infectious Diseases Society of America (IDSA) and the Society for Healthcare Epidemiology of America (SHEA) provided guidelines for the development of institutional programs to enhance antimicrobial stewardship. Experiences at The Ohio State University Medical Center (OSUMC) reinforce this message, while providing specific examples of ways to optimize ASP development and implementation. The focus of an ASP should be on improving quality of care, reducing drug resistance, and cost savings. When implementing an ASP, it is important to identify those most likely to resist the ASP, understand their concerns, and develop easy-to-understand messages that address these concerns and highlight the benefits of the proposed changes. Antibiograms play a key role in identifying local and interdepartmental trends in antibiotic susceptibility or resistance. These data are important not only in devising best-treatment practices for the institution, but also in evaluating the impact of a recently implemented ASP. Other measures of the impact of an ASP should include patient outcomes and overall costs or savings.

SUMMARY

Better antimicrobial stewardship is needed to limit the emergence of antibiotic resistance, prolong the effectiveness of currently available agents, improve patient outcomes, and reduce healthcare and societal costs associated with HAIs. Guidelines from the IDSA/SHEA and experiences at OSUMC provide examples of how best to develop an institutional ASP to accomplish these goals.

Ertapenem for the treatment of urinary tract infections caused by extended-spectrum β-lactamase-producing bacteria in children

BACKGROUND

Urinary tract infections (UTIs) are a problem frequently encountered by paediatric healthcare providers. Recent data suggest that extended-spectrum β-lactamase (ESBL)-producing bacteria are an emerging cause of UTIs in non-hospitalized patients. We report our experience of ertapenem use in 50 patients with complicated UTIs, mainly pyelonephritis, caused by ESBL-producing organisms.

METHODS

Fifty patients aged <16 y who had a complicated UTI caused by ESBL-producing organisms and who were treated with ertapenem at our hospital from 1 January 2009 to 31 December 2009, were included in the study.

RESULTS

There were 20 (40%) males and 30 (60%) females with a mean ± standard deviation age of 38.6 ± 36.9 months (range 6-156 months). Twenty-eight patients had no urological abnormality. In 40 patients ertapenem was initiated after results of microbiological cultures became available. Ertapenem was initiated empirically for 10 patients known to be colonized with ESBL-producing bacteria. Urine cultures were negative at 3.3 ± 0.7 days (range 2-5 days) after starting ertapenem treatment. The mean duration of ertapenem treatment was 7.8 ± 1.2 days (range 7-14 days). No laboratory or clinical side effects were observed.

CONCLUSIONS

Ertapenem is promising for the culture-guided treatment of ESBL-producing Gram-negative complicated UTIs. Well-designed prospective studies are needed to define the role of ertapenem in treating complicated paediatric UTIs, especially upper UTIs.

Osteomyelitis after bilateral sagittal split osteotomy: case report and a review of the management

OBJECTIVES

The purpose of this paper is to report a case of osteomyelitis following a bilateral sagittal split osteotomy in a patient who underwent 2-jaw surgery. A review of the management of osteomyelitis is included, with a discussion of implications for the reconstruction of the mandible after treatment for osteomyelitis.

STUDY DESIGN

A case of a rapidly progressing osteomyelitis is presented with a detailed review of the management of osteomyelitis, using this case to illustrate key points of management.

RESULTS

In a very short period of time the patient lost a significant portion of the left side of her mandible. The actual management that she underwent, as well as some of the controversies that are present with the treatment of osteomyelitis, is discussed.

CONCLUSION

Although osteomyelitis of the mandible usually is seen after odontogenic infections and trauma, it can occur in patients undergoing elective osteotomies. When recognized, it should be aggressively treated.

Prolonged Use of Ertapenem to Treat Infected Diabetic Foot Ulcers

We present the case of a diabetic man who was successfully treated with ertapenem for over 4 months for severe infection of his foot ulcers. After initial unsuccessful treatment with empirical intravenous antibiotics, ertapenem was started on microbiology advice and led to a marked improvement in the soft-tissue infection. Ertapenem was continued for a total of 137 days under close clinical and biochemical monitoring and produced a complete resolution of the foot infection. This is the first documented case that we know of in which ertapenem has been safely used for this duration of time.

[Update on antimicrobial chemotherapy]

There is a constant need for new antibacterial agents because of the unavoidable development of bacterial resistance that follows the introduction of antibiotics in clinical practice. As observed in many fields, innovation generally comes by series. For instance, a wide variety of broad-spectrum antibacterial agents became available between the 1970s and the 1990s, such as cephalosporins, penicillin/beta-lactamase inhibitor combinations, carbapenems, and fluoroquinolones. Over the last 2 decades, the arrival of new antibacterial drugs on the market has dramatically slowed, leaving a frequent gap between isolation of resistant pathogens and effective treatment options. In fact, many pharmaceutical companies focused on the development of narrow-spectrum antibiotics targeted at multidrug-resistant Gram-positive bacteria (e.g. methicillin-resistant Staphylococcus aureus, penicillin resistant Streptococcus pneumoniae, and vancomycin-resistant Enterococcus faecium). Therefore, multidrug-resistant Gram-negative bacteria (e.g. extended-spectrum beta-lactamase-producing Enterobacteriaceae, carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii) recently emerged and rapidly spread worldwide. Even if some molecules were developed, new molecules for infections caused by these multidrug-resistant Gram-negative bacteria remain remarkably scarce compared to those for Gram-positive infections. This review summarises the major microbiological, pharmacological, and clinical properties of systemic antibiotics recently marketed in France (i.e. linezolid, daptomycin, tigecycline, ertapenem, and doripenem) as well as those of antibacterial drugs currently in development (i.e. ceftobiprole, ceftaroline, dalbavancin, telavancin, oritavancin, iclaprim, and ramoplanin) or available in other countries (i.e. garenoxacin, sitafloxacin, and temocillin).

Ertapenem clearance during modeled continuous renal replacement therapy

PURPOSE

To determine ertapenem transmembrane clearance (CLtm) during continuous renal replacement therapy (CRRT) using a validated in vitro model.

METHODS

Ertapenem clearance during continuous hemofiltration and hemodialysis was assessed with AN69 and polysulfone hemodiafilters at 4 dialysate (Qd) and ultrafiltration rates (Quf): 1, 2, 3, and 6 l/hour. Blood and dialysate samples were collected at each flow rate and assayed for urea (control solute) and ertapenem concentrations. The experiment was repeated 5 times for each hemodiafilter type. Ertapenem and urea sieving coefficient (SC) and saturation coefficient (SA) were assessed, and CLtm calculated.

RESULTS

In continuous hemofiltration mode, urea and ertapenem SC ranged from 1.00 to 1.19 at all Quf and did not differ between hemodiafilter types. Consequently, convective CLtm also did not differ between hemodiafilters. In continuous dialysis mode, urea Cltm did not differ between hemodiafilter types at any Qd. However, ertapenem SA and CLtm were significantly different between hemodiafilter types at Qd 6l/hour (p<0.001). As Qd increased, mean +/- SD AN69 SA declined significantly from 0.87 +/- 0.12 at Qd 1 l/hour to 0.45 +/- 0.02 at Qd 6 l/hour (p<0.001). Ertapenem SA did not differ at any Qd with the polysulfone hemodiafilter (range 0.71-0.80).

CONCLUSION

Ertapenem was cleared substantially in these in vitro CRRT models. However, our findings illustrate discordance between our observed SC and SA and the published unbound fraction of ertapenem. This finding has been reported with many other drugs, including carbapenem antibiotics. If in vivo studies corroborate our SA and SC findings, dosage adjustment for patients receiving CRRT will be required.

The use of ertapenem for the treatment of lower extremity infections

Lower extremity infections are a growing challenge. Moderate to severe infections are frequently polymicrobial in nature and require appropriate parenteral antibiotic therapy. Ideally, empiric treatment should be broad spectrum in coverage, simplistic in use, and economically reasonable for the patient and the health care system. This article retrospectively reviewed the outcomes of 230 patients, 159 (69.13%) of whom were diabetic, who were admitted with lower extremity infections and who were empirically treated with ertapenem. Ertapenem was well tolerated with a low adverse effect profile. We found a 79.13% rate (182 of 230 patients) of favorable outcome with this regimen, which is comparable to other published studies that have looked at the use of this agent. Ertapenem is a once-daily, broad-spectrum carbapenem antibiotic indicated for the treatment of complicated skin and skin-structure infections (cSSSI). Ertapenem is an appropriate choice for empiric antibiotic therapy of lower extremity infections.

LEVEL OF CLINICAL EVIDENCE

2.

New developments in carbapenems

Antibiotic resistance among Gram-negative pathogens in hospitals is a growing threat to patients and is driving the increased use of carbapenems. Carbapenems are potent members of the beta-lactam family of antibiotics, with a history of safety and efficacy for serious infections that exceeds 20 years. Original and review articles were identified from a Medline search (1979-2008). Reference citations from identified publications, abstracts from the Interscience Conferences on Antimicrobial Agents and Chemotherapy and package inserts were also used. Carbapenems are effective in treating severe infections at diverse sites, with relatively low resistance rates and a favourable safety profile. Carbapenems are the beta-lactams of choice for the treatment of infections caused by multidrug-resistant organisms. Optimized dosing of carbapenems should limit the emergence of resistance and prolong the utility of these agents. The newly approved doripenem should prove to be a valuable addition to the currently available carbapenems: imipenem, meropenem and ertapenem.

Carbapenems versus other beta-lactams in the treatment of hospitalised patients with infection: a mixed treatment comparison

OBJECTIVE

To compare the effectiveness of meropenem with cefepime and piperacillin/tazobactam in the absence of direct comparisons in randomised controlled trials.

DATA SOURCES

Two previously conducted systematic reviews, one comparing the carbapenems (ertapenem and imipenem/cilastatin) versus 4th-generation cephalosporins (cefepime) or antipseudomonal penicillins (piperacillin/tazobactam), and the other comparing the carbapenems (imipenem/cilastatin versus meropenem), were updated to provide the basis for this mixed treatment comparison. Searching was completed in April 2007. No restriction was placed on language of publication.

STUDY SELECTION AND DATA EXTRACTION

Randomised controlled trials of adult patients hospitalised with infection and treated with a carbapenem or cefepime or piperacillin/tazobactam. Two reviewers independently assessed the papers against the inclusion/exclusion criteria and for methodological quality with any differences in opinion adjudicated by a third party. Two reviewers independently extracted data on clinical response, bacteriological response, mortality, and adverse events.

DATA SYNTHESIS

A mixed treatment comparison meta-analysis using Bayesian Markov Chain Monte Carlo simulation was used to perform the indirect comparison. The dataset comprised 34 trials: four comparing ertapenem versus piperacillin/tazobactam, one imipenem/cilastatin versus cefepime, 26 imipenem/cilastatin versus meropenem, three imipenem/cilastatin versus piperacillin/tazobactam. We calculated odds ratios (OR) using imipenem/cilastatin as the common comparator. Meropenem was associated with the highest probability of being the most effective treatment for clinical response (OR 1.52, 95% credible interval [CrI] 1.23-1.87) and bacteriological response (OR 1.45, 95% CrI 1.15-1.80) with a reduced risk of serious adverse events (overall: OR 0.88, 95% CrI 0.76-1.02; serious adverse events leading to withdrawal: OR 0.73, 95% CrI 0.42-1.20; and GI-related: OR 0.76, 95% CrI 0.55-1.02). There was little difference between the three carbapenems and cefepime on all-cause mortality.

CONCLUSIONS

This mixed treatment comparison suggests meropenem has substantial advantages over cefepime, ertapenem, imipenem/cilastatin and piperacillin/tazobactam in the treatment of hospitalised patients with infection.

Meropenem: a review of its use in the treatment of serious bacterial infections

Meropenem (Merrem, Meronem) is a broad-spectrum antibacterial agent of the carbapenem family, indicated as empirical therapy prior to the identification of causative organisms, or for disease caused by single or multiple susceptible bacteria in both adults and children with a broad range of serious infections. Meropenem is approved for use in complicated intra-abdominal infection (cIAI), complicated skin and skin structure infection (cSSSI) and bacterial meningitis (in paediatric patients aged > or = 3 months) in the US, and in most other countries for nosocomial pneumonia, cIAI, septicaemia, febrile neutropenia, cSSSI, bacterial meningitis, complicated urinary tract infection (UTI), obstetric and gynaecological infections, in cystic fibrosis patients with pulmonary exacerbations, and for the treatment of severe community-acquired pneumonia (CAP). Meropenem has a broad spectrum of in vitro activity against Gram-positive and Gram-negative pathogens, including extended-spectrum beta-lactamase (ESBL)- and AmpC-producing Enterobacteriaceae. It has similar efficacy to comparator antibacterial agents, including: imipenem/cilastatin in cIAI, cSSSI, febrile neutropenia, complicated UTI, obstetric or gynaecological infections and severe CAP; clindamycin plus tobramycin or gentamicin in cIAI or obstetric/gynaecological infections; cefotaxime plus metronidazole in cIAI; cefepime and ceftazidime plus amikacin in septicaemia or febrile neutropenia; and ceftazidime, clarithromycin plus ceftriaxone or amikacin in severe CAP. Meropenem has also shown similar efficacy to cefotaxime in paediatric and adult patients with bacterial meningitis, and to ceftazidime when both agents were administered with or without tobramycin in patients with cystic fibrosis experiencing acute pulmonary exacerbations. Meropenem showed greater efficacy than ceftazidime or piperacillin/tazobactam in febrile neutropenia, and greater efficacy than ceftazidime plus amikacin or tobramycin in patients with nosocomial pneumonia. Meropenem is well tolerated and has the advantage of being suitable for administration as an intravenous bolus or infusion. Its low propensity for inducing seizures means that it is suitable for treating bacterial meningitis and is the only carbapenem approved in this indication. Thus, meropenem continues to be an important option for the empirical treatment of serious bacterial infections in hospitalized patients.

Crystal structures of biapenem and tebipenem complexed with penicillin-binding proteins 2X and 1A from Streptococcus pneumoniae

Biapenem is a parenteral carbapenem antibiotic that exhibits wide-ranging antibacterial activity, remarkable chemical stability, and extensive stability against human renal dehydropeptidase-I. Tebipenem is the active form of tebipenem pivoxil, a novel oral carbapenem antibiotic that has a high level of bioavailability in humans, in addition to the above-mentioned features. beta-lactam antibiotics, including carbapenems, target penicillin-binding proteins (PBPs), which are membrane-associated enzymes that play essential roles in peptidoglycan biosynthesis. To envisage the binding of carbapenems to PBPs, we determined the crystal structures of the trypsin-digested forms of both PBP 2X and PBP 1A from Streptococcus pneumoniae strain R6, each complexed with biapenem or tebipenem. The structures of the complexes revealed that the carbapenem C-2 side chains form hydrophobic interactions with Trp374 and Thr526 of PBP 2X and with Trp411 and Thr543 of PBP 1A. The Trp and Thr residues are conserved in PBP 2B. These results suggest that interactions between the C-2 side chains of carbapenems and the conserved Trp and Thr residues in PBPs play important roles in the binding of carbapenems to PBPs.

Carbapenems versus other beta-lactams in treating severe infections in intensive care: a systematic review of randomised controlled trials

Carbapenems have not been comprehensively compared in clinical trials with fourth-generation cephalosporins (4GC) and antipseudomonal penicillins (APP) in the treatment of severe infections (SI) and febrile neutropenia (FN). A systematic review of CENTRAL, EMBASE, MEDLINE and JICST-EPlus for randomised controlled trials was conducted to establish the currently available evidence. Database searching was supplemented by hand searching and contacting conference organisers. Searching was completed in November 2006 and no restriction was placed on the language of publication. Data were extracted on clinical response, bacteriologic response, all-cause mortality and adverse events. Of the 265 papers identified, 12 were appropriate for meta-analysis (four 4GC and eight APP). The results showed that carbapenems are associated with a significant reduction in all-cause mortality (relative risk 0.62, 95% confidence interval: 0.41 to 0.95; p=0.03) compared to APP in the treatment of SI, and withdrawals due to adverse events (RR 0.65, 95% CI: 0.45 to 0.96; p=0.03) are also less common. When compared in the treatment of FN, carbapenems are associated with a significant increase in clinical response during the initial 72 h of treatment (RR 1.37, 95% CI: 1.09 to 1.74; p=0.008) and bacteriologic response (RR 1.73, 95% CI: 1.03 to 2.89; p=0.04). For all other outcomes, including all comparisons with 4GC, there were no significant differences between treatments. The use of carbapenems rather than APP could reduce mortality and, by simplifying treatment decisions, reduce the time before patients receive appropriate antibiotic treatment. The currently available evidence is insufficient for distinguishing between carbapenems and 4GC.