Ertapenem: a Group 1 carbapenem with distinct antibacterial and pharmacological properties

A Rare Case of Late-Onset Ertapenem-Induced Encephalopathy

Encephalopathy is a rare side effect associated with carbapenem antibiotics, typically presenting within one week of initiating treatment. It is almost exclusively seen in patients with poor renal function. We present a case of a middle-aged male with a history of cerebral vascular accident and normal renal function admitted for agitation, delirium, and insomnia more than two weeks after starting ertapenem to treat osteomyelitis. He was empirically treated for meningitis on admission, and ertapenem was discontinued. After an extensive negative workup for infectious and neurological etiologies of encephalopathy, a presumptive diagnosis of ertapenem-induced encephalopathy was made. The patient returned to his baseline mental status five days after discontinuing ertapenem. The nature of his neurological symptoms and timely resolution after stopping ertapenem is consistent with ertapenem-induced encephalopathy and represents a notably delayed symptom onset compared to previously described cases.

Ertapenem-Induced Neurotoxicity: A Literature Review of Clinical Characteristics and Treatment Outcomes

Background

Neurotoxicity is a rare adverse event for ertapenem. Given the limited evidence, large patient data are needed to aid in the identification and management of this fatal complication. Aim of the review, we summarize the characteristics, risk factors, and treatment of ertapenem-induced neurotoxicity.

Methods

Pubmed, Web of Science, Embase, Cochrane library, Wanfang, CNKI, China VIP database were searched up from 31 October 2001 to 31 December 2022. All articles concerning neurotoxicity induced by ertapenem were included. The retrieved articles were screened by two experienced clinicians by reading the titles, abstracts, and full texts.

Results

A total of 66 patients were included, with a median age of 71.5 years (range 40-92), of whom 45 (68.2%) were male. Twelve patients (18.2%) received irrational doses (exceeding the recommended dose), and 30 patients (45.5%) had chronic renal insufficiency. The median time to symptom onset was 5 (range 1-14). Epileptiform seizures (42.4%), visual hallucinations (36.4%), altered mental status (25.8%), and confusion (22.7%) were the most common symptoms of ertapenem-induced neurotoxicity. Of the 29 patients with reported albumin levels, 25 had serum albumin <3.5 g/dl. Ertapenem was discontinued in 95.5% of patients, and 90.9% recovered completely. Median time to symptom recovery was 7 days (range 1-42) after intervention including antiepileptic administration, or hemodialysis.

Conclusion

Neurotoxicity is a rare adverse event for ertapenem, especially in patients with advanced age, renal insufficiency, pre-existing neurological disease, and hypoalbuminemia. This adverse reaction usually resolves with medication interruption, or antiepileptic administration and hemodialysis.

A Proposal for a Classification Guiding the Selection of Appropriate Antibiotic Therapy for Intra-Abdominal Infections

Adequately controlling the source of infection and prescribing appropriately antibiotic therapy are the cornerstones of the management of patients with intra-abdominal infections (IAIs). Correctly classifying patients with IAIs is crucial to assessing the severity of their clinical condition and deciding the strategy of the treatment, including a correct empiric antibiotic therapy. Best practices in prescribing antibiotics may impact patient outcomes and the cost of treatment, as well as the risk of “opportunistic” infections such as Clostridioides difficile infection and the development and spread of antimicrobial resistance. This review aims to identify a correct classification of IAIs, guiding clinicians in the selection of the best antibiotic therapy in patients with IAIs.

β-Lactam antibiotic targets and resistance mechanisms: from covalent inhibitors to substrates

The β-lactams are the most widely used antibacterial agents worldwide. These antibiotics, a group that includes the penicillins and cephalosporins, are covalent inhibitors that target bacterial penicillin-binding proteins and disrupt peptidoglycan synthesis. Bacteria can achieve resistance to β-lactams in several ways, including the production of serine β-lactamase enzymes. While β-lactams also covalently interact with serine β-lactamases, these enzymes are capable of deacylating this complex, treating the antibiotic as a substrate. In this tutorial-style review, we provide an overview of the β-lactam antibiotics, focusing on their covalent interactions with their target proteins and resistance mechanisms. We begin by describing the structurally diverse range of β-lactam antibiotics and β-lactamase inhibitors that are currently used as therapeutics. Then, we introduce the penicillin-binding proteins, describing their functions and structures, and highlighting their interactions with β-lactam antibiotics. We next describe the classes of serine β-lactamases, exploring some of the mechanisms by which they achieve the ability to degrade β-lactams. Finally, we introduce the l,d-transpeptidases, a group of bacterial enzymes involved in peptidoglycan synthesis which are also targeted by β-lactam antibiotics. Although resistance mechanisms are now prevalent for all antibiotics in this class, past successes in antibiotic development have at least delayed this onset of resistance. The β-lactams continue to be an essential tool for the treatment of infectious disease, and recent advances (e.g., β-lactamase inhibitor development) will continue to support their future use.

Transcriptome-based design of antisense inhibitors potentiates carbapenem efficacy in CRE Escherichia coli

In recent years, the prevalence of carbapenem-resistant Enterobacteriaceae (CRE) has risen substantially, and the study of CRE resistance mechanisms has become increasingly important for antibiotic development. Although much research has focused on genomic resistance factors, relatively few studies have examined CRE pathogens through changes in gene expression. In this study, we examined the gene expression profile of a CRE Escherichia coli clinical isolate that is sensitive to meropenem but resistant to ertapenem to explore transcriptomic contributions to resistance and to identify gene knockdown targets for carbapenem potentiation. We sequenced total and short RNA to analyze the gene expression response to ertapenem or meropenem treatment and found significant expression changes in genes related to motility, maltodextrin metabolism, the formate hydrogenlyase complex, and the general stress response. To validate these findings, we used our laboratory's Facile Accelerated Specific Therapeutic (FAST) platform to create antisense peptide nucleic acids (PNAs), gene-specific molecules designed to inhibit protein translation. PNAs were designed to inhibit the pathways identified in our transcriptomic analysis, and each PNA was then tested in combination with each carbapenem to assess its effect on the antibiotics' minimum inhibitory concentrations. We observed significant PNA-antibiotic interaction with five different PNAs across six combinations. Inhibition of the genes hycA, dsrB, and bolA potentiated carbapenem efficacy in CRE E. coli, whereas inhibition of the genes flhC and ygaC conferred added resistance. Our results identify resistance factors and demonstrate that transcriptomic analysis is a potent tool for designing antibiotic PNA.

Successful Use of Ertapenem for the Treatment of Enterobacter cloacae Complex Infection of the Central Nervous System (CNS)

A 55-year-old female with a past medical history of cocaine use and hypertension was admitted for intracranial hemorrhage requiring right decompressive craniotomy with duraplasty. Due to persistent fevers, a head CT scan obtained on day 28 of hospitalization identified a low-density subgaleal fluid collection overlying the duraplasty. Aspiration of this collection was sent for culture which grew 2+ Enterobacter cloacae complex susceptible to sulfamethoxazole-trimethoprim (SMX-TMP), gentamicin, ciprofloxacin, and ertapenem. Based on these results, the patient was transitioned from empiric vancomycin and ceftazidime to SMX-TMP and metronidazole. Despite treatment with SMX-TMP and metronidazole, aspirated subgaleal collection cultures remained positive for E. cloacae. Intrathecal gentamicin was therefore added; however, repeat subgaleal culture collections remained persistently positive. Given the persistently positive subgaleal culture collections, the patient was transitioned from SMX-TMP and metronidazole to ertapenem. After transition to ertapenem, subgaleal cultures were sterilized and the patient's infection was resolved. This report suggests ertapenem may be a viable option for central nervous system infections; however, further study is needed.

Ertapenem-associated neurotoxicity in the spinal cord injury (SCI) population: A case series

Context Ertapenem, a broad spectrum carbapenem antibiotic, is used often in Spinal Cord Injury (SCI) patients due to increased risk factors for multi-drug resistant (MDR) infections in this population. Neurotoxicity, specifically seizures, due to ertapenem is a known adverse effect and has been described previously. Other manifestations such as delirium and visual hallucinations have rarely been reported, and no literature, to the best of our knowledge, specifically describes these effects solely in the SCI population. Findings Four cases of mental status changes and hallucinations in SCI patients attributed to ertapenem therapy are described. Onset of symptoms began between one and six days following initiation of ertapenem and resolved between two to 42 days following discontinuation. Based on the Naranjo probability scale, a probable relationship exists between the adverse events and ertapenem for three out of the four cases. Possible overestimation of renal function and hypoalbuminemia may be contributing factors to the noted adverse reactions. Conclusion/Clinical Relevance The cases described highlight the importance of recognizing ertapenem-associated hallucinations in SCI patients. The population is particularly vulnerable due to risk factors for MDR infections necessitating ertapenem use, possible overestimation of renal function, and a high prevalence of hypoalbuminemia.

Pharmacokinetics of 2,000 Milligram Ertapenem in Tuberculosis Patients

Ertapenem is a carbapenem antibiotic with activity against Mycobacterium tuberculosis Dose simulations in a hollow-fiber infection model showed that 2,000 mg once daily is an appropriate dose to be tested in clinical studies. Before using this dose in a phase II study, the aim of this prospective pharmacokinetic study was to confirm the pharmacokinetics of 2,000 mg once daily in tuberculosis (TB) patients. Twelve TB patients received a single intravenous dose of 2,000 mg ertapenem as a 30-min infusion. Blood samples were collected at 0, 0.5, 1, 2, 3, 4, 8, 12, and 24 h postadministration. Drug concentrations were measured using a validated liquid chromatography-tandem mass spectrometry assay. A large interindividual variation in the pharmacokinetics of ertapenem was observed. The median (interquartile range) area under the plasma concentration-time curve to infinity (AUC_0-∞) was 2,032 (1,751 to 2,346) mg · h/liter, the intercompartmental clearance (CL₁₂) was 1.941 (0.979 to 2.817) liters/h, and the volume of distribution in the central compartment (V₁) was 1.514 (1.064 to 2.210) liters. A more than dose-proportional increase in AUC was observed compared to results reported for 1,000 mg ertapenem in multidrug-resistant TB patients. Based on a MIC of 1.0 mg/liter, 11 out of 12 patients would have reached the target value of unbound drug exceeding the MIC over 40% of the time (f40% T>MIC). In conclusion, this study shows that 2,000 mg ertapenem once daily in TB patients reached the expected f40% T>MIC for most of the patients, and exploration in a phase 2 study can be advocated.

Molecular Characterization of Carbapenemase-Nonproducing Clinical Isolates of Escherichia coli (from a Thai University Hospital) with Reduced Carbapenem Susceptibility

Twelve nonreplicate carbapenemase-negative ertapenem (ETP)-nonsusceptible (CNENS) Escherichia coli isolates obtained at a Thai university hospital between 2010 and 2014 were characterized and compared with 2 carbapenemase-producing E. coli isolates from the same hospital. Eight unique pulsed-field gel electrophoresis patterns were obtained. All the isolates produced CTX-M-15 β-lactamase and 2 either coexpressed CMY-2 cephalosporinase or showed increased efflux pump activity. Amino acid sequence analysis revealed that an OmpF defect (in 7 isolates) due to mutations generating truncated proteins or an IS1 insertion was more prevalent than a defect in OmpC was (no truncated proteins detected). Seven out of 10 isolates possessing OmpC variants with any OmpF defect were weakly ETP-resistant (minimum inhibitory concentrations [MICs] of 1-4 μg/mL) and imipenem (IPM)- and meropenem (MEM)-susceptible (MICs 0.125-0.5 μg/mL). Two isolates with ompC PCR-negative results and an OmpF defect showed higher carbapenem MICs (8-32, 1-8, and 1-4 μg/mL for ETP, IPM, and MEM, respectively) with the highest MICs associated with the additional efflux pump activity. Both carbapenemase producers possessing CTX-M-15 and a porin background identical to that in the CNENS isolates showed ETP, IPM, and MEM MICs of 128-256, 8, and 2-32 μg/mL, respectively. These findings suggest that a porin defect combined with CTX-M-15 production is the major mechanism of low carbapenem susceptibility among our CNENS isolates, which have potential to become strongly carbapenem-resistant because of additional carbapenemase or efflux pump activities.

Ertapenem-Induced Thrombocytosis

Ertapenem is a β-lactam antibiotic that has a broad spectrum of anti-microbial coverage. Hematological adverse events like thrombocytosis, neutropenia, and neutropenia are infrequent. Here we report a rare case of drug-induced thrombocytosis in a 68-year-old female, who was treated with ertapenem for the diagnosis of complicated abdominal infection. This case emphasizes that any patient with thrombocytosis should be assessed with a careful and detailed history with consideration for possible drug side effects.

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.

Status Epilepticus and Delirium Associated with Ertapenem in a Very Elderly Patient with Chronic Kidney Disease and Silent Ischaemic Cerebrovascular Disease

An 85-year-old female with chronic kidney disease and newly acquired seizures on oral phenytoin received intravenous ertapenem 500 mg once daily for a urinary tract infection and bacteraemia involving extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli. After three ertapenem doses, she developed seizures which self-aborted. Corrected phenytoin level was sub-therapeutic initially, but became therapeutic following a phenytoin dose increase. On Day 14 of ertapenem, the patient suffered another episode of seizure. Ertapenem was stopped. On Day 15, she developed status epilepticus lasting 2 days, requiring intravenous lorazepam, sodium valproate and phenytoin. The last episode of seizure occurred 3 days after discontinuation of ertapenem, with a dramatic recovery of her Glasgow Coma Scale and resolution of delirium. At the time of writing, she has remained seizure free for over 2 years. A retrospective audit of the emergency department notes revealed that she had a course of ertapenem in another institution prior, which also led to two seizure episodes—once 8 days after starting ertapenem, another 3 days after stopping ertapenem. Despite using a renal-adjusted ertapenem dose, each dip in her creatinine clearance level was associated with seizures, preceded by delirium each time. Naranjo assessment score was 6, suggesting a probable relationship between the seizures and ertapenem.

Mechanisms of β-lactam killing and resistance in the context of Mycobacterium tuberculosis

β-Lactams are one of the most useful classes of antibiotics against many common bacterial pathogens. One exception is Mycobacterium tuberculosis. However, with increasing incidence of multidrug-resistant tuberculosis and a need for new agents to treat it, the use of β-lactams, specifically the combination of carbapenem and clavulanate, is now being revisited. With this attention, comes the need to better understand both the mechanisms of action of β-lactams against M. tuberculosis as well as possible mechanisms of resistance, within the context of what is known about the β-lactam action in other bacteria. M. tuberculosis has two major mechanisms of intrinsic resistance: a highly active β-lactamase and a poorly permeable outer membrane. Within the cell wall, β-lactams bind several enzymes with differing peptidoglycan-synthetic and -lytic functions. The inhibition of these enzymes may lead to cell death through several mechanisms, involving disruption of the balance of synthetic and lethal activities. Currently, all known means of resistance to the β-lactams rely on diminishing the proportion of peptidoglycan-synthetic proteins bound and inhibited by β-lactams, through either exclusion or destruction of the antibiotic, or through replacement or supplementation of target enzymes. In this review, we discuss possible mechanisms for β-lactam activity in M. tuberculosis and the means by which it may acquire resistance, within the context of what is known in other bacterial species.

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.

Delayed recovery from ertapenem induced encephalopathy: case-report and a possible mechanism

CASE

The objective of this case report is to report a patient with moderate renal impairment who developed ertapenem-induced encephalopathy with delayed recovery of up to 2 weeks despite receiving and appropriately adjusted dosage of ertapenem. The patient was managed conservatively with full recovery. Carbapenem related neurotoxicity most commonly manifests as seizure with an estimated incidence of 3 %. There are increasing reports of encephalopathy being related to ertapenem and most commonly subsides within days and extended recovery of up to 2 weeks have only been reported in patients with end-stage renal failure.

CONCLUSIONS

Prolonged ertapenem induced encephalopathy can occur in patients with moderate renal impairment. These patients can be managed conservatively and they should make a complete recovery.

2013 WSES guidelines for management of intra-abdominal infections

Despite advances in diagnosis, surgery, and antimicrobial therapy, mortality rates associated with complicated intra-abdominal infections remain exceedingly high.The 2013 update of the World Society of Emergency Surgery (WSES) guidelines for the management of intra-abdominal infections contains evidence-based recommendations for management of patients with intra-abdominal infections.

Antimicrobials in urogenital infections

Urinary tract infections (UTIs) and male genital infections are amongst the most prevalent infections. A prudent antibiotic policy therefore has a large impact on society. The clinical classification in uncomplicated cystitis, uncomplicated pyelonephritis, complicated UTI and genital infections is useful, also for the right choice of antibiotic treatment. In this regard pharmacokinetic and pharmacodynamic aspects have to be considered. Nowadays in uncomplicated cystitis antibiotics exclusively reserved for this indication are preferred, such as fosfomycin trometamol, nitrofurantoin and pivmecillinam, in order to reduce antibiotic pressure in this extremely frequent entity. In complicated UTI a broad bacterial spectrum has to be considered. Different antibiotic substances should be used for treatment, such as penicillins, with β-lactamase inhibitors, cephalosporins or carbapenems, fluoroquinolones, aminoglycosides or cotrimoxazole, if tested susceptible. For genital infections the pharmacokinetic properties of the antibiotics should especially be considered, such as in prostatitis, where mainly fluoroquinolones and macrolides show sufficient pharmacokinetic parameters for treatment of bacterial infections. Furthermore in genital infections fastidious organisms, such as Chlamydia or Mycoplasma spp. have to be considered with respect to their antimicrobial susceptibility.

WSES consensus conference: Guidelines for first-line management of intra-abdominal infections

Intra-abdominal infections are still associated with high rate of morbidity and mortality.A multidisciplinary approach to the management of patients with intra-abdominal infections may be an important factor in the quality of care. The presence of a team of health professionals from various disciplines, working in concert, may improve efficiency, outcome, and the cost of care.A World Society of Emergency Surgery (WSES) Consensus Conference was held in Bologna on July 2010, during the 1st congress of the WSES, involving surgeons, infectious disease specialists, pharmacologists, radiologists and intensivists with the goal of defining recommendations for the early management of intra-abdominal infections.This document represents the executive summary of the final guidelines approved by the consensus conference.

Pharmacokinetics and tolerability of single-dose intravenous ertapenem in infants, children, and adolescents

BACKGROUND

Ertapenem is a carbapenem antibiotic with broad spectrum activity and a pharmacokinetic profile that favors once-daily administration in adults.

OBJECTIVES

This investigation was designed to evaluate the dose-exposure profile of ertapenem in children from infancy through adolescence.

METHODS

Eighty-four children (3 months-16 years) requiring antibiotic therapy were enrolled in this multicenter trial. Children received a single intravenous dose of ertapenem at 15, 20, or 40 mg/kg followed by repeated blood sampling for 24 hours. Free and total plasma ertapenem concentrations were quantitated by high-performance liquid chromatography, and the pharmacokinetics were determined using a model-independent approach.

RESULTS

Ertapenem exposure increased proportionally with increasing dose; however, achievable concentrations were influenced by age. Children older than 12 years attained higher dose-normalized concentrations at the end of the infusion (concentration at the end of the infusion [Ceoi]: 8.7 ± 1.9 mg/L per mg/kg dose) and total body exposure (area under the curve area under the plasma concentration-time curve [AUC]0-∞: 34.7 ± 14.7 mg hr/L per mg/kg dose) as compared with children 2 to 12 years (Ceoi: 6.9 ± 2.4 mg/L per mg/kg dose, AUC0-∞: 18.4 ± 8.0 mg hr/L per mg/kg dose) and children younger than 2 years (Ceoi: 6.1 ± 2.2 mg/L per mg/kg dose, AUC0-∞: 17.0 ± 5.4 mg hr/L per mg/kg dose). These findings were accounted for by age-dependent changes in ertapenem clearance and distribution volume. In 3 children adverse events (nausea, n = 2; injection site reaction, n = 1) were considered related to study drug administration.

CONCLUSIONS

Children younger than 12 years require dosing more frequently than once daily to achieve optimal efficacy when treating organisms with a minimum inhibitory concentration near the susceptibility breakpoint.

A focus on intra-abdominal infections

Complicated intra-abdominal infections are an important cause of morbidity and are frequently associated with poor prognosis, particularly in higher risk patients.

Well defined evidence-based recommendations for intra-abdominal infections treatment are partially lacking because of the limited number of randomized-controlled trials.

Factors consistently associated with poor outcomes in patients with intra-abdominal infections include increased illness severity, failed source control, inadequate empiric antimicrobial therapy and healthcare-acquired infection.

Early prognostic evaluation of complicated intra-abdominal infections is important to select high-risk patients for more aggressive therapeutic procedures.

The cornerstones in the management of complicated intra-abdominal infections are both source control and antibiotic therapy.

The timing and the adequacy of source control are the most important issues in the management of intra-abdominal infections, because inadequate and late control of septic source may have a negative effect on the outcomes.

Recent advances in interventional and more aggressive techniques could significantly decrease the morbidity and mortality of physiologically severe complicated intra-abdominal infections, even if these are still being debated and are yet not validated by limited prospective trials.

Empiric antimicrobial therapy is nevertheless important in the overall management of intra-abdominal infections. Inappropriate antibiotic therapy may result in poor patient outcomes and in the appearance of bacterial resistance.

Antimicrobial management is generally standardised and many regimens, either with monotherapy or combination therapy, have proven their efficacy. Routine coverage especially against Enterococci and candida spp is not always recommended, but can be useful in particular clinical conditions. A de escalation approach may be recommended in patients with specific risk factors for multidrug resistant infections such as immunodeficiency and prolonged antibacterial exposure.

Therapy should focus on the obtainment of adequate source control and adequate use of antimicrobial therapy dictated by individual patient risk factors. Other critical issues remain debated and more controversies are still open mainly because of the limited number of randomized controlled trials.

How beta-lactam antibiotics enter bacteria: a dialogue with the porins

Background

Multi-drug resistant (MDR) infections have become a major concern in hospitals worldwide. This study investigates membrane translocation, which is the first step required for drug action on internal bacterial targets. β-lactams, a major antibiotic class, use porins to pass through the outer membrane barrier of Gram-negative bacteria. Clinical reports have linked the MDR phenotype to altered membrane permeability including porin modification and efflux pump expression.

Methodology/Principal Findings

Here influx of β-lactams through the major Enterobacter aerogenes porin Omp36 is characterized. Conductance measurements through a single Omp36 trimer reconstituted into a planar lipid bilayer allowed us to count the passage of single β-lactam molecules. Statistical analysis of each transport event yielded the kinetic parameters of antibiotic travel through Omp36 and distinguishable translocation properties of β-lactams were quantified for ertapenem and cefepime. Expression of Omp36 in an otherwise porin-null bacterial strain is shown to confer increases in the killing rate of these antibiotics and in the corresponding bacterial susceptibility.

Conclusions/Significance

We propose the idea of a molecular “passport” that allows rapid transport of substrates through porins. Deciphering antibiotic translocation provides new insights for the design of novel drugs that may be highly effective at passing through the porin constriction zone. Such data may hold the key for the next generation of antibiotics capable of rapid intracellular accumulation to circumvent the further development MDR infections.

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.

A comparison of the stability of ertapenem and meropenem in pharmaceutical preparations in solid state

The following first-order rate constants of the degradation of ertapenem in INVANZ and meropenem in MERONEM were determined: (a) in dry air at 363, 373, 378, 383, 388, 393 K; (b) at increased relative air humidity (76.4% RH) at 313, 323, 333 and 343 K; (c) at increased relative air humidity (50.9, 60.5, 66.5, 76.4% RH-ertapenem and 50.9, 66.5, 76.4 and 90.0% RH-meropenem) at 333 K. The dependence ln k(i) = f(RH%) was described by the equations: ln k(i) = (6.63+/-1.22) x 10(-2) x (RH%)-13.36 +/- 1.68 (ertapenem) and ln k(i) = (4.22 +/- 2.98) x 10(-2) x (RH%)-12.14 +/- 2.16 (meropenem). The dependence lnk(i)=f(1/T) was described by equations: ln k(i) =19.4 +/- 2.6-(9230 +/- 800)(1/T) for ertapenem, at 76.4% RH; ln k(i) = 11.5 +/- 4.9-(9880 +/- 1800)(1/T) for ertapenem in dry air; ln k(i) = 14.8 +/- 11.9-(7785 +/- 3905)(1/T) for meropenem, at 76.4% RH; ln k(i) = 37.6 +/- 7.73-(18385 +/- 2930)(1/T) for meropenem in dry air. The thermodynamic parameters E(a), DeltaH( not equal) and DeltaS( not equal) of the degradation of ertapenem and meropenem were calculated. The difference between the influence of temperature on the stability of ertapenem and meropenem was not significant at 76.4% RH. In dry air (363-393 K) this influence was greater in the case of meropenem. The degradation of ertapenem was slower in this temperature range. Humidity was a significant factor affecting the degradation of these antibiotics and it influenced their stability is similar ways.

Profilaxia antimicrobiana na cirurgia bariátrica

OBJETIVO: Analisar os resultados da incidência de infecção do sítio cirúrgico com três diferentes esquemas antimicrobianos. MÉTODO: No período de Janeiro de 1999 a Dezembro de 2004 foram realizadas 716 cirurgias para o tratamento da Obesidade mórbida, seguindo a técnica proposta por Fobi/Capella. Foram estudados comparativamente três grupos de pacientes: Grupo I - (185) em que foi realizada a profilaxia antimicrobiana com ampicilina/sulbactam, na dose de 3g em duas doses; Grupo II (280) em que a profilaxia foi com ceftriaxona na dose de 1g (dose única); e Grupo III (251) em que a profilaxia foi com ertapenem, na dose de 1 g (dose única). RESULTADOS: O resultado do presente estudo demonstra taxas de infecção do sítio cirúrgico de 3,78% no grupo de profilaxia com ampicilina-sulbactam, 6,81% no grupo de profilaxia com ceftriaxona e de 1,99% no grupo de ertapenem. Não houve diferença estatisticamente significativa entre o uso da associação ampicilina/sulbactam ou ceftriaxona com relação à incidência de infecção do sítio cirúrgico. No entanto, quando comparados os resultados do Grupo II (Ceftriaxona) com o Grupo III (Ertapenem), houve uma diferença estatisticamente sisgnificante. CONCLUSÃO: A utilização do ertapenem, de maneira profilática, no tratamento cirúrgico da obesidade mórbida, determinou taxas de infecção do sítio cirúrgico estatisticamente inferiores ao grupo de ceftriaxona e similar ao de ampicilina-sulbactam.

Ertapenem: the new carbapenem 5 years after first FDA licensing for clinical practice

Ertapenem, a parenteral broad-spectrum 1-beta-methyl-carbapenem, was licensed 5 years ago for clinical practice in the US and Europe. The substance has a good in vitro activity against many common aerobic and anaerobic Gram-positive and -negative bacteria. Its in vitro activity against Enterobacteriaceae carrying plasmid- or chromosomal-mediated beta-lactamases, including AmpC- and extended-spectrum beta-lactamases, is especially clinically significant. Advantages concerning in vitro activity and low potential for so-called 'collateral damage', and development of own resistance during therapy, as shown in several randomized, controlled clinical trials, make ertapenem an excellent treatment choice for complicated aerobic and anaerobic mix infections caused by ertapenem-sensitive bacteria. On the other hand, due to its limited activity against Acinetobacter spp., enterococci and Pseudomonas aeruginosa, it is less suitable for late-onset nosocomial infections. International guidelines recommend the initial empirical use of ertapenem for intra-abdominal infections, skin and skin-structure infections, acute pelvic infections, complicated urinary tract infections and pneumonia (both community-acquired and 'early-onset' nosocomial) in a dose of 1.0 g administered once daily. However, recent results from pharmacokinetic/pharmacodynamic modelling studies in critically ill patients with ventilator-associated pneumonia and adipose volunteers with a body mass index of > or = 20 kg/m(2) showed that the standard dose of 1.0 g/day may not provide adequate free, protein-unbound drug concentrations in plasma and organ tissues. Therefore, a shortening of the dosage interval or continuous infusion of ertapenem should be considered to ensure optimal free concentrations in these particular populations.

In vitro activities of ertapenem against drug-resistant Streptococcus pneumoniae and other respiratory pathogens from 12 Asian countries

In vitro activities of ertapenem and 11 other comparator agents were tested against 1025 isolates of respiratory pathogens collected from 12 Asian countries. Resistance rate to ertapenem was 1.2% in 602 isolates of Streptococcus pneumoniae (MIC(50), 0.06/MIC(90), 1 microg/mL). Ertapenem was also very active against penicillin-, ciprofloxacin-, erythromycin-, and multidrug-resistant pneumococcal isolates (resistance rate: 3.5%, 2.7%, 1.9%, and 2.7%, respectively). Ertapenem-resistant pneumococcal isolates were found only in Vietnam and Korea. Ertapenem resistance was not found in methicillin-susceptible Staphylococcus aureus, Haemophilus influenzae, Moraxella catarrhalis, and Klebsiella pneumoniae, including extended-spectrum beta-lactamase producers. In vitro data suggest that ertapenem could be a useful treatment option for community-acquired pneumonia.

Unexpected Four-Membered over Six-Membered Ring Formation during the Synthesis of Azaheterocyclic Phosphonates: Experimental and Theoretical Evaluation

The cyclization of functionalized aminophosphonates is studied on both experimental and theoretical grounds. In a recently described route to phosphono-beta-lactams [Stevens C. V.; Vekemans, W.; Moonen, K.; Rammeloo, T. Tetrahedron Lett. 2003, 44, 1619], it was found that starting from an ambident allylic anion only four-membered rings were formed without any trace of six-membered lactams. New anion trapping experiments revealed that the gamma-anion is highly reactive in intermolecular reactions. Ab initio calculations predict higher reaction barriers for the gamma-anion due to restricted rotation about the C-N bond and due to highly strained transition states during ring closure. The sodium or lithium counterion, explicit dimethyl ether solvent molecules, and bulk solvent effects were properly taken into account at various levels of theory.

Quantification of the carbapenem antibiotic ertapenem in human plasma by a validated liquid chromatography–mass spectrometry method

BACKGROUND

Ertapenem (Invanz) is a newly developed carbapenem beta-lactam antibiotic. LC-MS is the method of choice for therapeutic drug monitoring (TDM) of a variety of drugs including antibiotics. No validated LC-MS method for ertapenem quantification is described in the literature so far.

METHODS

A rapid and robust LC-MS quantification method for ertapenem was developed and validated for clinical routine application in plasma samples. After immediate stabilisation with MES buffer (pH 6.5), samples were prepared for LC-MS analysis using simple protein precipitation. LC-MS coupling was realised by the use of a Phenomenex Synergi 4micro Polar-RP A80 Mercury LC column (10 x 2.0 mm) in combination with a Single-MS (Agilent 1100 LC-MSD SL) operating in negative selected ion monitoring (SIM) detection mode with ceftazidime as internal standard for adequate selective and sensitive analysis.

RESULTS

LC-MS method validation by means of determination of limit of detection (LOD 0.1 microg mL-1), lower limit of quantification (LLOQ 1 microg mL-1), linearity (0.1-50 microg mL-1), recovery (> 90%), intra- and inter-day precision (RSD < 10%), accuracy (> 90%), inter-subject variability (< 10% at LLOQ), drug stability in plasma (> 3 months) and in post-extracted samples (> 99% for 24 h), and matrix effects (process efficiency > 90%) showed excellent performance parameters considering Guidance for Industry - Bioanalytical Method Validation.

CONCLUSION

This method is perfectly appropriate for routine quantification of ertapenem and possibly other polar carbapenem beta-lactam antibiotics.

Determination of free ertapenem in plasma and bronchoalveolar lavage by high-performance liquid chromatography with ultraviolet detection

A sensitive assay for the determination of unbound ertapenem in human plasma and bronchoalveolar lavage (BAL) was developed using ultrafiltration of plasma and BAL samples. A rapid HPLC method was used with ultraviolet detection set at a wavelength of 305 nm and a separation on a Prontosil AQ C18 column, with imipenem used as internal standard. This assay was linear over the concentration range of 0.5-100 microg/mL and 0.25-50 microg/mL in plasma and BAL, respectively. Limits of detection and quantitation were respectively 0.05 and 0.25 microg/mL. Validation data for accuracy and precision were CV<2.48 and 8.25%, accuracy in the range 98.1-104.2% and 102.2-108.4%, respectively, for intra and inter-day.

Ertapenem: review of a new carbapenem

The carbapenems are beta-lactam-type antibiotics with an exceptionally broad spectrum of activity. Ertapenem is a new carbapenem developed to address the pharmacokinetic shortcomings (short half-life) of imipenem and meropenem. Ertapenem shares similar structural features with meropenem, including its stability to dehydropeptidase-1, allowing it to be administered without a dehydropeptidase-1 inhibitor. Ertapenem, like imipenem and meropenem, demonstrates broad-spectrum antimicrobial activity against many Gram-positive and -negative aerobes and anaerobes and is resistant to nearly all beta-lactamases, including extended-spectrum beta-lactamases and AmpCs. However, it differs from both imipenem and meropenem in demonstrating limited activity against Enterococcusspp., Pseudomonasaeruginosa and other nonfermentative Gram-negative bacteria commonly associated with nosocomial infections. The extensive protein binding of ertapenem extends the half-life and allows for once-daily dosing. Prospective, multicenter, randomized, double-blind, comparative clinical studies demonstrate similar clinical efficacy of ertapenem compared with other agents. Clinical trials of complicated intra-abdominal infection, acute pelvic infection, complicated skin and soft-structure infection, community-acquired pneumonia and complicated urinary tract infections demonstrated that ertapenem has equivalent efficacy and safety compared with ceftriaxone and piperacillin/tazobactam. Ertapenem is a promising new carbapenem with excellent efficacy and safety for the treatment of a variety of community-acquired infections. It also appears to be of great value as an outpatient parenteral antimicrobial therapy.