Evaluation of Ertapenem use with impact assessment on extended-spectrum beta-lactamases (ESBL) production and gram-negative resistance in Singapore General Hospital (SGH)

[Antimicrobial stewardship program in urinary tract infections due to multiresistant strains in the emergency department]

OBJECTIVE

Urinary tract infections (UTI) are a frequent reason for attendance at emergency department (ED). The present study evaluates the impact of a multidisciplinary program for the optimization of antibiotic therapy in patients with UTI caused by multi-drug resistant bacteria treated from the hospital ED.

METHODS

Descriptive study of the implementation of a program in which emergency, microbiology and pharmacy departments participated. Antibiotic treatment of the patients who consulted the ED with positive urine cultures caused by multidrug-resistant bacteria was reviewed upon discharge. In those patients with inappropriate treatment, doctors and/or pharmacists of the next level of healthcare or patients in the case of home discharge were contacted. The impact of the program was evaluated based on new visits to the ED at 30 days after discharge, compared with the results obtained from the usual practice three months prior the intervention.

RESULTS

During the first year, 2,474 urine cultures of patients with UTI were reviewed, 533 (21.7%) were caused by multidrug-resistant bacteria. Empirical treatment was inappropriate in 287 (53.4%), making treatment modifications in 243 of them. 73 (19.3%) patients returned to the ED 30 days after discharge, being lower than the results obtained in the three months prior intervention (27.9%; p=0.031), without significant differences in new visits associated with UTI.

CONCLUSIONS

The implementation of a multidisciplinary program focused on multidrug resistant UTI at discharge form ED correct antibiotic therapy in a large number of patients, being a potentially tool to reduce the number of new ED visits.

Cefazolin plus ertapenem and heart transplantation as salvage therapy for refractory LVAD infection due to methicillin-susceptible Staphylococcus aureus: A case series

The use of left ventricular assist devices (LVADs) is increasingly more common as the availability of donor organs in relation to failing hearts is outstandingly limited. Infections are the most common complications in LVAD recipients, particularly those caused by Staphylococcus spp. Refractory LVAD-related infections are not uncommon as achieving adequate source control is often not feasible before heart transplantation. Evidence suggest that cefazolin plus ertapenem is effective in refractory methicillin-susceptible Staphylococcus aureus (MSSA) bacteremia, but this approach has not been described in LVAD recipients. In this article, we report two cases of refractory MSSA bacteremia in LVAD recipients that were successfully treated with salvage therapy with cefazolin plus ertapenem and subsequent heart transplantation. This treatment strategy should be considered in patients with refractory LVAD-associated infection due to MSSA that are not responding to standard treatment.

Retrospective assessment of antimicrobial stewardship initiative in outpatient use of ertapenem for uncomplicated extended spectrum beta lactamase Enterobacteriaceae urinary tract infections

BACKGROUND

Urinary tract infections (UTI) are often over-diagnosed and over-treated, which can induce and select for resistant pathogens. After observing wide-spread outpatient use of ertapenem, a broad-spectrum antibiotic, a structured antimicrobial stewardship initiative (ASI) to improve appropriate antimicrobial prescribing was undertaken. ASI objectives were to achieve a goal of reducing ertapenem utilization for extended spectrum beta lactamase Enterobacteriaceae (ESBL-EB) UTI by 10% and evaluate the clinical outcomes associated with the ASI.

METHODS

A pre-to-post cohort study was conducted at a single-center integrated healthcare system between November 1, 2014 and February 26, 2017. An intensive, 90-day, pharmacist-driven, structured ASI was implemented between November 1, 2015 and January 29, 2016. Female patients aged ≥18 years who were treated for an uncomplicated, ESBL-EB urinary tract infection (UTI) were included. Primary outcome was clinical resolution defined as cure, persistence, relapse and recurrence. Secondary outcome measured was monthly ertapenem use expressed as number of days of therapy (DOT)/1000 adjusted patient days (APD). Segmented regression analysis for interrupted time series was performed to estimate ASI intervention effect.

RESULTS

A total of 184 patients were included in the study. Ertapenem utilization decreased from 0.0145 DOT/1000 APD in Nov. 2014 to 0.0078 DOT/1000 APD Feb. 2017(p < 0.01). The mean ertapenem DOT declined 19% overall from the pre vs. post intervention periods (32 vs 26, p < 0.01). Frequency of recurrent UTIs between treatments did not significantly differ and no adverse effects were reported in patients treated with aminoglycosides.

CONCLUSIONS

A structured ASI for uncomplicated ESBL-EB UTI was associated with a clinically meaningful decrease in ertapenem utilization and once-daily, 5-day aminoglycoside treatment was well-tolerated.

Discovery of beta-lactamase CMY-10 inhibitors for combination therapy against multi-drug resistant Enterobacteriaceae

β-lactam antibiotics are the most widely used antimicrobial agents since the discovery of benzylpenicillin in the 1920s. Unfortunately, these life-saving antibiotics are vulnerable to inactivation by continuously evolving β-lactamase enzymes that are primary resistance determinants in multi-drug resistant pathogens. The current study exploits the strategy of combination therapeutics and aims at identifying novel β-lactamase inhibitors that can inactivate the β-lactamase enzyme of the pathogen while allowing the β-lactam antibiotic to act against its penicillin-binding protein target. Inhibitor discovery applied the Site-Identification by Ligand Competitive Saturation (SILCS) technology to map the functional group requirements of the β-lactamase CMY-10 and generate pharmacophore models of active site. SILCS-MC, Ligand-grid Free Energy (LGFE) analysis and Machine-learning based random-forest (RF) scoring methods were then used to screen and filter a library of 700,000 compounds. From the computational screens 74 compounds were subjected to experimental validation in which β-lactamase activity assay, in vitro susceptibility testing, and Scanning Electron Microscope (SEM) analysis were conducted to explore their antibacterial potential. Eleven compounds were identified as enhancers while 7 compounds were recognized as inhibitors of CMY-10. Of these, compound 11 showed promising activity in β-lactamase activity assay, in vitro susceptibility testing against ATCC strains (E. coli, E. cloacae, E. agglomerans, E. alvei) and MDR clinical isolates (E. cloacae, E. alvei and E. agglomerans), with synergistic assay indicating its potential as a β-lactam enhancer and β-lactamase inhibitor. Structural similarity search against the active compound 11 yielded 28 more compounds. The majority of these compounds also exhibited β-lactamase inhibition potential and antibacterial activity. The non-β-lactam-based β-lactamase inhibitors identified in the current study have the potential to be used in combination therapy with lactam-based antibiotics against MDR clinical isolates that have been found resistant against last-line antibiotics.

Carbapenem stewardship with ertapenem and antimicrobial resistance-a scoping review

Consumption of carbapenem has increased due to extended-spectrum beta-lactamase-producing bacteria spreading. Ertapenem has been suggested as a not carbapenem-resistance inducer. We performed a scoping review of carbapenem-sparing stewardship with ertapenem and its impact on the antibiotic resistance of Gram-negative bacilli. We searched PubMed for studies that used ertapenem as a strategy to reduce resistance to carbapenems and included epidemiologic studies with this strategy to evaluate susceptibility patterns to cephalosporins, quinolones, and carbapenems in Gram-negative-bacilli. The search period included only studies in English, up to February 2018. From 1294 articles, 12 studies were included, mostly from the Americas. Enterobacteriaceae resistance to quinolones and cephalosporins was evaluated in 6 studies and carbapenem resistance in 4 studies. Group 2 carbapenem (imipenem/meropenem/doripenem) resistance on A. baumannii was evaluated in 6 studies. All studies evaluated P. aeruginosa resistance to Group 2 carbapenem. Resistance profiles of Enterobacteriaceae and P. aeruginosa to Group 2 carbapenems were not associated with ertapenem consumption. The resistance rate of A. baumannii to Group 2 carbapenems after ertapenem introduction was not clear due to a lack of studies without bias. In summary, ertapenem as a strategy to spare use of Group 2 carbapenems may be an option to stewardship programs without increasing resistance of Enterobacteriaceae and P. aeruginosa. More studies are needed to evaluate the influence of ertapenem on A. baumannii.

Trends in and Predictors of Carbapenem Consumption across North American Hospitals: Results from a Multicenter Survey by the MAD-ID Research Network

We sought to define trends in and predictors of carbapenem consumption across community, teaching, and university-affiliated hospitals in the United States and Canada. We conducted a retrospective multicenter survey of carbapenem and broad-spectrum noncarbapenem beta-lactam consumption between January 2011 and December 2013. Consumption was tabulated as defined daily doses (DDD) or as days of therapy (DOT) per 1,000 patient days (PD). Multivariate mixed-effects models were explored, and final model goodness of fit was assessed by regressions of observed versus predicted values and residual distributions. A total of 20 acute-care hospitals responded. The centers treated adult patients (n = 19/20) and pediatric/neonatal patients (n = 17/20). The majority of the centers were nonprofit (n = 17/20) and not affiliated with medical/teaching institutions (n = 11/20). The median (interquartile range [IQR]) carbapenem consumption rates were 38.8 (17.4 to 95.7) DDD/1,000 PD and 29.7 (19.2 to 40.1) DOT/1,000 PD overall. Carbapenem consumption was well described by a multivariate linear mixed-effects model (fixed effects, R ² = 0.792; fixed plus random effects, R ² = 0.974). Carbapenem consumption increased by 1.91-fold/quarter from 48.6 DDD/1,000 PD (P = 0.004) and by 0.056-fold/quarter from 45.7 DOT/1,000 PD (P = 0.93) over the study period. Noncarbapenem consumption was independently related to increasing carbapenem consumption (beta = 0.31 for increasing noncarbapenem beta-lactam consumption; P < 0.001). Regular antibiogram publication and promotion of conversion from intravenous (i.v.) to oral (p.o.) administration independently affected carbapenem consumption rates. In the final model, 58.5% of the observed variance in consumption was attributable to between-hospital differences. Rates of carbapenem consumption across 20 North American hospitals differed greatly, and the observed differences were correlated with hospital-specific demographics. Additional studies focusing on the drivers of hospital-specific carbapenem consumption are needed to determine whether these rates are justifiable.

Non-intravenous carbapenem-sparing antibiotics for definitive treatment of bacteraemia due to Enterobacteriaceae producing extended-spectrum β-lactamase (ESBL) or AmpC β-lactamase: A propensity score study

Carbapenems are considered the treatment of choice for extended-spectrum β-lactamase (ESBL)- or AmpC β-lactamase-producing Enterobacteriaceae bacteraemia. Data on the effectiveness of non-intravenous carbapenem-sparing antibiotic options are limited. This study compared the 30-day mortality and clinical failure associated with the use of carbapenems versus alternative non-intravenous antibiotics for the definitive treatment of ESBL/AmpC-positive Enterobacteriaceae bacteraemia. This 12-year retrospective study (2004-2015) included all patients with bacteraemia due to ESBL/AmpC-producing Enterobacteriaceae at a Spanish hospital. Given the lack of randomisation of initial therapies, a propensity score for receiving carbapenems was calculated. There were 1115 patients with a first episode of bacteraemia due to Escherichia coli or Klebsiella pneumoniae, of which 123 (11.0%) were ESBL/AmpC-positive. There were 101 eligible patients: 59 in the carbapenem group and 42 in the alternative treatment group (trimethoprim/sulfamethoxazole 59.5%, quinolones 21.4%). The most frequent sources of infection were urinary (63%) and biliary (15%). Compared with the carbapenem group, patients treated with an alternative regimen had a shorter hospital stay [median (IQR) 7 (5-10) days vs. 12 (9-18) days; P < 0.001]. Use of an alternative non-intravenous therapy did not increase mortality (OR = 0.27, 95% CI 0.05-1.61; P = 0.15). After controlling for confounding factors with the propensity score, the adjusted OR of carbapenem treatment was 4.95 (95% CI 0.94-26.01; P = 0.059). Alternative non-intravenous carbapenem-sparing antibiotics could have a role in the definitive treatment of ESBL/AmpC-positive Enterobacteriaceae bacteraemia, allowing a reduction in carbapenem use. Use of trimethoprim/sulfamethoxazole in this series showed favourable results.

Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party

The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.

Correlation between antimicrobial consumption and the prevalence of carbapenem-resistant Escherichia coli and carbapenem-resistant Klebsiella pneumoniae at a university hospital in Thailand

WHAT IS KNOWN AND OBJECTIVE

Carbapenem-resistant Enterobacteriaceae (CRE) are virulent gram-negative bacilli and cause urgent healthcare problems worldwide. One of the main factors leading to the emergence of CRE is antimicrobial consumption. The objective of this study was to assess how closely the rate of antimicrobial consumption and the prevalences of carbapenem-resistant Escherichia coli (CR-EC) and carbapenem-resistant Klebsiella pneumoniae (CR-KP) are correlated.

METHODS

A retrospective study was performed at a university hospital in Thailand from January 2013 to September 2016. The prevalence of E coli and K pneumoniae was represented as percentages per species per quarter. The antimicrobial consumption rate per quarter was expressed as the defined daily dose (DDD)/1000 patient-days. Evaluation of the relationships between the rate of antimicrobial consumption and the prevalences of CR-EC and CR-KP was conducted via Pearson's or Spearman's correlation analyses.

RESULTS AND DISCUSSION

During the study period, the prevalence of CR-EC and CR-KP was less than 6%; however, significantly increasing prevalences were reported for both CR-EC (r = 0.55, P = 0.03) and CR-KP (r = 0.87, P < 0.01). There was a significant increasing trend in the consumption of meropenem (r = 0.65, P = 0.01), levofloxacin (r = 0.63, P = 0.01), ceftriaxone (r = 0.55, P = 0.03), ertapenem (r = 0.52, P = 0.05) and the carbapenem group (r = 0.64, P = 0.01). A significant correlation was observed between CR-KP prevalence and total carbapenem consumption (r = 0.55, P = 0.04). Moreover, levofloxacin consumption had a significant positive relationship with the prevalence of CR-KP (r = 0.65, P = 0.01). No positive correlation was found with the prevalence of CR-EC.

WHAT IS NEW AND CONCLUSION

The rate of consumption of levofloxacin and carbapenems was the important key factor correlated with the rate of emergence of CR-KP. This is the first report demonstrating the correlation between levofloxacin consumption and CR-KP prevalence.

Treatment of Infections Caused by Extended-Spectrum-Beta-Lactamase-, AmpC-, and Carbapenemase-Producing Enterobacteriaceae

Therapy of invasive infections due to multidrug-resistant Enterobacteriaceae (MDR-E) is challenging, and some of the few active drugs are not available in many countries. For extended-spectrum β-lactamase and AmpC producers, carbapenems are the drugs of choice, but alternatives are needed because the rate of carbapenem resistance is rising. Potential active drugs include classic and newer β-lactam-β-lactamase inhibitor combinations, cephamycins, temocillin, aminoglycosides, tigecycline, fosfomycin, and, rarely, fluoroquinolones or trimethoprim-sulfamethoxazole. These drugs might be considered in some specific situations. AmpC producers are resistant to cephamycins, but cefepime is an option. In the case of carbapenemase-producing Enterobacteriaceae (CPE), only some "second-line" drugs, such as polymyxins, tigecycline, aminoglycosides, and fosfomycin, may be active; double carbapenems can also be considered in specific situations. Combination therapy is associated with better outcomes for high-risk patients, such as those in septic shock or with pneumonia. Ceftazidime-avibactam was recently approved and is active against KPC and OXA-48 producers; the available experience is scarce but promising, although development of resistance is a concern. New drugs active against some CPE isolates are in different stages of development, including meropenem-vaborbactam, imipenem-relebactam, plazomicin, cefiderocol, eravacycline, and aztreonam-avibactam. Overall, therapy of MDR-E infection must be individualized according to the susceptibility profile, type, and severity of infection and the features of the patient.

Cefmetazole for bacteremia caused by ESBL-producing enterobacteriaceae comparing with carbapenems

Background

ESBL (Extended spectrum beta-lactamase) producing enterobacteriaceae are challenging organisms with little treatment options. Carbapenems are frequently used, but the emergence of carbapenem resistant enterobacteriaceae is a concerning issue, which may hinder the use of carbapenems. Although cephamycins such as cefoxitin, cefmetazole or cefotetan are effective against ESBL-producers in vitro, there are few clinical data demonstrating effects against bacteremia caused by these organisms.

Methods

We performed a retrospective observational study on cases of bacteremia caused by ESBL-producers to investigate the efficacy of cefmetazole compared with carbapenems. We also evaluated whether the trend of antibiotic choice changed over years.

Results

Sixty-nine patients (male 34, age 69.2 ± 14.4), including two relapse cases, were reviewed for this analysis. The most common causative organisms were Escherichia coli (64, 93 %), followed by Klebsiella pneumoniae and K. oxytoca (2 each, 4 %). The group that received carbapenem therapy (43, 62 %) had increased severity in the Pittsburgh Bacteremic score than the group that received cefmetazole therapy, (1.5 ± 1.5 vs 2.5 ± 2.1, p = 0.048), while analysis of other factors didn’t reveal any statistical differences. Five patients in the carbapenem group and one patient in the cefmetazole group died during the observation period (p = 0.24). CTX-M-9 were predominant in this series (59 %). Infectious disease physicians initially recommended carbapenems at the beginning of the current research period, which gradually changed over time favoring the use of cefmetazole instead (p = 0.002).

Conclusion

Cefmetazole may be safely given to patients with bacteremia caused by ESBL-producers as a definitive therapy, if one can select out relatively stable patients.