Carbapenem Stewardship Research Articles

Carbapenem use in extended-spectrum cephalosporin-resistant Enterobacterales infections in US hospitals and influence of IDSA guidance: a retrospective cohort study

Disparate and rapidly changing practice recommendations from major professional infectious diseases societies for managing non-severe infections caused by extended-spectrum β-lactamase-producing Enterobacterales might hamper carbapenem stewardship. We aimed to understand the real-world management of extended-spectrum cephalosporin-resistant (ECR) Enterobacterales infections in US hospitals and factors influencing preference for carbapenems over alternative treatments. This retrospective cohort study included adults (aged ≥18 years) admitted to hospital with ECR Enterobacterales infections in the PINC AI database. Antibiotic regimens were assessed during empirical and targeted treatment periods and by infection severity and site. Likelihood of receiving targeted carbapenems over time and before or after initial release of the Infectious Diseases Society of America (IDSA) guidance on Sept 8, 2020, was established with generalised estimating equations controlling for patient, hospital, and temporal confounders. Between Jan 1, 2018, and Dec 31, 2021, 30 041 inpatient encounters with ECR Enterobacterales infections were identified at 168 US hospitals, of which 16 006 (53·3%) encounters were in women and 14 035 (46·7%) were in men, with a mean age of 67·3 years (SD 15·1). Although few patients received carbapenems empirically (5324 [17·7%] of 30 041), many did so as targeted treatment (17 518 [58·3%] of 30 041), including subgroups of patients without septic shock (3031 [45·6%] of 6651) and patients with urinary tract infections without septic shock (1845 [46·8%] of 3943) in whom specific narrower-spectrum alternatives were active. Transitions from non-carbapenem to carbapenem antibiotics occurred most often on the day that the ECR phenotype was reported, regardless of illness severity. Carbapenems were the predominant choice to treat ECR Enterobacterales infections over time (adjusted odds ratio 1·00 [95% CI 1·00-1·00]), with no additional immediate change (1·07 [0·95-1·20]) or sustained change (0·99 [0·98-1·00]) after IDSA guidance release. High carbapenem use in targeting non-severe ECR Enterobacterales infections in US hospitals predates 2020 IDSA guidance and has persisted thereafter. Efforts to increase awareness and implementation of recommendations among clinicians to use carbapenem-sparing alternatives in ECR Enterobacterales infections might decrease global carbapenem selective pressure. US National Institutes of Health Intramural Research Program, National Institute of Allergy and Infectious Diseases, and US Food and Drug Administration.

Clinical impact of multidisciplinary carbapenem stewardship interventions: a retrospective cohort study.

Antimicrobial stewardship (AMS) program aims to optimise antimicrobial utilisation and curb antimicrobial resistance. We investigated the clinical impact of AMS among patients with carbapenem in medical wards of a tertiary hospital. A retrospective cohort study was conducted on hospitalised adult patients treated with carbapenem and reviewed by a multidisciplinary AMS team. We compared the clinical outcomes of accepted (n = 103) and not-accepted AMS intervention cases (n = 37). The outcomes evaluated include trends of total white blood cells (TWBC), C-reactive protein (CRP), body temperature at day-7, and clinical status at day-30 post-AMS intervention. The interventions included discontinuation (50%), de-escalation (47.9%) and escalation (2.1%) of antibiotics, where the acceptance rate was 67.1%, 80.6% and 66.7%, respectively. Overall, we found no significant difference in clinical outcomes between accepted and not-accepted AMS interventions at day-7 and day-30 post-interventions. On day-7, 62.0% of patients in the accepted group showed decreased or normalised TWBC and CRP levels compared to 47.4% of the not-accepted group (p = 0.271). The mortality at day-30 (32% versus 35%, p = 0.73), discharge rate (53.4% versus 45.9%, p = 0.437), and median length of hospital stay (36.0 versus 30.0days, p = 0.526) between the groups were comparable. The predictors of 30-day mortality in the study subjects were Charlson Comorbidity Index > 3 (OR: 2.84, 95% CI 1.28-6.29, p = 0.010) and being febrile at day-7 (OR: 4.58, 95% CI 1.83-11.5, p = 0.001). AMS interventions do not result in significant adverse clinical impact and mortality risk.

Effect of a national antibiotic stewardship intervention in China targeting carbapenem overuse: An interrupted time-series analysis

To assess trends and patterns of carbapenem use and to evaluate the effects of a nationwide antibiotic stewardship policy to reduce carbapenem overuse. In this quasi-experimental study, using longitudinal data from the national drug procurement database and interrupted time-series analyses with carbapenems as the intervention group and possible carbapenem substitutes as the comparison group, we evaluated the effects of a national stewardship policy on carbapenem consumption and expenditures, by region and types of healthcare institutions. The carbapenem procurement volume declined by -28.8% (95% CI -35.0 to -22.6) (-334.4 thousand defined daily doses [DDDs] per month), and carbapenem expenditures showed a relative reduction of -38.1% (-43.9 to -32.2). The gap between the use of carbapenems and each drug in the comparison group narrowed after the policy intervention, with an increase in tigecycline use (14.9 thousand DDDs [10.8-18.9]) and a slower decrease in use of certain third-generation cephalosporin combinations (-85.7 [-143.0 to -28.4]), penicillin combinations (-200.9 [-421.4-19.6]), and fourth-generation cephalosporins (-116.9 [-219.8 to -14.0]). Consumption was highest during the pre-policy period, and declines were largest following the intervention in the eastern region (-32.1%, -39.8 to -24.4) and among tertiary hospitals (-266.2 [-339.5 to -192.9] thousand DDDs per month). This population-level drug utilization research represents the first comprehensive evaluation of the effectiveness of China's nationwide carbapenem stewardship. The national policy targeting carbapenem prescribing has led to a sustained reduction in carbapenem use with limited substitution. Effects varied geographically and were concentrated in tertiary and secondary hospitals.

Carbapenem stewardship program in a French university children's hospital

IntroductionCarbapenems, last-resort antibiotics, are widely used as first-line treatment in patients carrying extended-spectrum beta-lactamases (ESBL) Enterobacteriaceae, including in a pediatric setting. We aimed to implement an antibiotic stewardship program (ASP) to improve the use of carbapenems. MethodsWe implemented an ASP at the Bordeaux Children's University Hospital with 6-month audits on prescribing practice before and after an intervention (revision of antibiotic treatment protocols, a half-day educational session with feedback of the first study period). The number of carbapenem prescriptions was analyzed and two criteria were used to assess conformity of the indication for carbapenem prescription and conformity of the reassessment. A logistic regression was used to assess the overall compliance of carbapenem prescriptions over the two periods adjusted for ESBL carriage. ResultsA total of 57 patients were included with 37 carbapenem prescriptions before the intervention and 23 after. Overall carbapenem consumption decreased from 0.54 prescriptions per 100 admissions to 0.32 (p = 0.06). Conformity increased during the study for indication (46–87%, p = 0.004) and for reassessment (48–78%, p = 0.04) and was significantly associated with the second study period, after adjustment for ESBL carriage. ConclusionOur intervention contributed to a significant improvement in the compliance to indications for carbapenem indication and in the reassessment of the prescription.

157. A Multidisciplinary Approach to Carbapenem Stewardship at a Large Community Hospital in Brooklyn, New York

BackgroundCarbapenem-resistant gram-negative organisms are a continuously mounting threat, underscoring the need for effective antimicrobial stewardship interventions to improve the use of carbapenems. We sought to implement several multidisciplinary antimicrobial stewardship interventions beginning in January 2019 in an effort to reduce unnecessary meropenem use and the incidence of carbapenem-resistant gram-negatives.MethodsProspective audit and feedback was utilized daily in combination with weekly stewardship rounds between an Infectious Diseases pharmacist and physician in the Intensive Care Units. A second Infectious Diseases physician attended weekly interdisciplinary rounds on meropenem high-use units. Meropenem Days of Therapy (DOT) per 1,000 patient days and the incidence of meropenem resistant Pseudomonas aeruginosa and Klebsiella pneumoniae were compared by the chi-square test of proportions.ResultsBetween 2018 and 2019 the institution’s meropenem DOT per 1,000 patient days decreased 33%, from 57 to 38 days per 1,000 patient days (difference, 19 days per 1,000 patient days; p< 0.001). In the hospital antibiogram, the meropenem susceptibility of Pseudomonas aeruginosa over the same time period increased from 71% to 77% of isolates (difference, 6%; p = 0.009). A non-significant decrease in the susceptibility of meropenem to Klebsiella pneumoniae was also observed from 92 to 90% (difference, 2%: p = 0.1658).ConclusionThese data support the need for antimicrobial stewardship efforts targeting broad-spectrum antimicrobials such as meropenem. In the setting of a sustained decrease in meropenem use over 12 months, we observed a significant improvement in the percent susceptibility rate of Pseudomonas aeruginosa to meropenem for the first time in five years.Disclosures All Authors: No reported disclosures

Outcomes of Extended-Spectrum Beta-Lactamase Gram-Negative Bacteremia Cases Treated With Carbapenem Versus Noncarbapenem Antibiotics

Background: The rising prevalence of infections caused by extended-spectrum β-lactamase (ESBL)–producing bacteria increases reliance on carbapenems, which intensifies selection pressure for the emergence of carbapenem-resistant Enterobacteriaceae (CRE). Whether noncarbapenem (nC) antibiotics can be safely used in this setting remains incompletely understood. Objective: To examine the safety of carbapenem stewardship in this population, we compared outcomes of uncomplicated ESBL bacteremia treated with a carbapenem to those treated with a noncarbapenem regimen. Methods: A retrospective chart review of patients with ESBL bacteremia from 2014 to 2018 in a 5-hospital regional health system was conducted. Patients aged &lt;18 years, with polymicrobial bacteremia, whose infections required a prolonged length of antibiotic therapy (LOT), or who died on antibiotic treatment or transitioned to hospice, were excluded. Groups were stratified based on the antibiotic regimen with the highest number of treatment days during the treatment course. Outcome measures included empiric and definitive length of therapy (LOT), 30-day all-cause mortality, 90-day readmission, recurrence of ESBL bacteremia, hospital length of stay (LOS), incidence of Clostridioides difficile infection (CDI) and adverse drug events, obtained by Wilcoxon rank-sum testing, χ2 test, and Fisher exact test, as applicable. Results: In total, 112 unique patients had ESBL bacteremia; 42 were excluded, leaving 70 for analysis. Of these, 57 were treated with a carbapenem regimen and 13 patients were treated with a noncarbapenem regimen: 9 ciprofloxacin, 3 gentamicin, 1 TMP-SMX. Patient baseline and antibiotic regimen characteristics were similar (Table 1). The most common organism was E. coli, and the most common source was urinary. A similar proportion of each group received ESBL-active empiric antibiotics. There were no significant differences in total effective antibiotic LOT, 30-day all-cause mortality, 90-day readmission, or recurrence of ESBL bacteremia (Table 2). A nonsignificant trend in hospital LOS was observed in the noncarbapenem group (11 vs 6 days; P = .055). Conclusions: Although the sample size was small, these multicenter data suggest that noncarbapenem treatment of ESBL bacteremia may be safe and effective. Pending confirmatory studies, ESBL bacteremia may be an important target for carbapenem stewardship.Funding: NoneDisclosures: None

Opportunities for antimicrobial stewardship among carbapenem-treated patients in 18 North American hospitals

Here we describe the characteristics of carbapenem use at 18 hospitals across North America. Adult inpatients treated with a carbapenem for ≥24 h were included in this multicentre, retrospective, cross-sectional study. Outcomes evaluated included classification of therapy as empirical or definitive, discharge disposition and 30-day re-admission. A total of 621 patients were included in this study. Of these, 467 patients (75.2%) received a carbapenem empirically, among whom negative cultures occurred in 313 (67.0%) and 93% were eligible for de-escalation of therapy. In-hospital mortality occurred in 72 patients (11.6%) and 549 patients (88.4%) were discharged. Of the 549 patients who were discharged, 349 patients (63.6%) went home and 30-day infection-related re-admission occurred in 95 patients (17.3%). This population represents a significant need for carbapenem stewardship. Institutional guidelines should focus on four common disease states (respiratory, genitourinary, intra-abdominal and bloodstream), and diagnostic stewardship should be employed to aid in rapid de-escalation of carbapenem therapy. Additional studies aiming to identify antimicrobial stewardship techniques that may help to optimise carbapenem therapy and increase education about the importance of utilising carbapenem-sparing regimens are required.

Carbapenem stewardship in a large teaching English hospital - are we improving?

Background:Overuse of antibiotics has been linked to the global growth of antimicrobial resistance (AMR). In 2018, increase in meropenem usage in our hospital revealed that we achieved the “Start Smart” but not “Then Focus” element. Following revised carbapenem stewardship, we aimed to evaluate the adherence to guidelines, by monitoring patients initiated on meropenem. Methods:As part of the antimicrobial stewardship (AMS) at our 1800-bed teaching hospital, carbanepem stewardship was revised in September 2018 and required consultant approval for all carbapenem initiation or continuation following specialist advice. Meropenem prescriptions in adult and paediatric patients were generated from the electronic prescription system and reviewed daily for one week in August 2019 to ascertain if prescribed in line with guideline recommendations or on the advice of microbiology or infectious diseases. Results:Sixty patients were reviewed. Microbiology or Infectious Diseases recommendation was obtained in 37% of patients. 95% had samples taken where blood cultures accounted for 85% but over a third of these had no growth reported. Meropenem was initiated empirically in 50% of patients mainly for neutropenic sepsis while 28% were culture directed. 35% of patients were escalated from piperacillin-tazobactam of which 57% had neutropenia while de-escalation occurred in 10%. Conclusion:AMR is related directly to antibiotic use at a patient level. Our revised strategy resulted in a reduction of total carbapenem DDD/1000 Admission from 128 (June 2018) to 87 (June 2019) through improved adherence to guideline and infection specialists recommendations however more work is required to promote switch to narrower-spectrum choice.

1102. Ertapenem vs. Nonertapenem Antibiotics in Colorectal Surgery: A Stewardship Opportunity

BackgroundThe optimal regimen for antibiotic prophylaxis in colorectal surgery is not well defined. The aim of this study was to determine whether nonertapenem antibiotic prophylaxis in colorectal surgery is associated with increased rates of surgical site infections (SSI), defined by both deep and incisional infections, compared with ertapenem prophylaxis. Secondary aims were to identify differences in C. difficile infection rates at 60 days between the two groups.MethodsThis was a single-center retrospective study from November 2016 to December 2018 at a 600-bed teaching hospital equipped with a Level I Trauma Center in Central Texas. National Healthcare Safety Network (NHSN) criteria for colorectal surgical site infection (SSI) were used to identify eligible patients. Patients under 18 years or lacking pre-operative antibiotic documentation were excluded. SSI and C. difficile rates between the two prophylactic strategies were compared using Chi-squared and Fisher’s exact tests as appropriate.ResultsA total of 761 patients were included in the analysis. There were 87 patients in the ertapenem group and 674 patients in the nonertapenem group. Antibiotics included in the nonertapenem group were cefazolin (32%), ceftriaxone (22%), or ciprofloxacin (15%) plus metronidazole, and other antibiotics (31%). Baseline characteristics including age, American Society of Anesthesiologists (ASA) score, body mass index (BMI), and number of surgical procedures were similar for both groups. The overall SSI rate was 4.7% and the 60-day C. difficile rate was 3.9%. No significant differences were found between ertapenem and nonertapenem groups in SSI rates (5.8% vs. 4.6%, P = 0.6) or 60-day incidence of C. difficile (6.9% vs. 3.6%, P = 0.1).ConclusionOur study, with a large sample size and a low overall incidence of SSI, did not find a significant difference in either SSI rates or 60-day C. difficile rates between ertapenem and nonertapenem prophylaxis in colorectal surgery. Given the rise of Gram-negative resistance, this study highlights an important opportunity for carbapenem stewardship.Disclosures All authors: No reported disclosures.

Pseudomonas Endocarditis with an unstable phenotype: the challenges of isolate characterization and Carbapenem stewardship with a partial review of the literature

BackgroundPseudomonas endocarditis is exceedingly rare, especially in patients without predisposing risks. We present such a case that included unexpected switches in antibacterial resistance profiles in two Pseudomonas aeruginosa (PA) strains with the same whole-genome sequence. The case also involved diagnostic and treatment challenges, such as issues with automated testing platforms, choosing the optimal aminoglycoside, minimizing unnecessary carbapenem exposure, and the need for faster, more informative laboratory tests.Case presentationOn hospital day one (HD-1) a cefepime and piperacillin-tazobactam (FEP-TZP)-susceptible P. aeruginosa was isolated from the bloodstream of a 62-year-old man admitted for evaluation of possible endocarditis and treated with gentamicin and cefepime. On HD-2, his antibiotic regimen was changed to tobramycin and cefepime. On HD-11, he underwent aortic valve replacement, and P. aeruginosa was isolated from the explanted valve. Unexpectedly, it was FEP-TZP-resistant, so cefepime was switched to meropenem. On HD-14, in preparation for whole-genome sequencing (WGS), valve and blood isolates were removed from cryo-storage, re-cultured, and simultaneously tested with the same platforms, reagents, and inoculations previously used. Curiously, the valve isolate was now FEP-TZP-susceptible. WGS revealed that both isolates were phylogenetically identical, differing by a single nucleotide in a chemotaxis-encoding gene. They also contained the same resistance genes (blaADC35, aph(3′)-II, blaOXA-50, catB7, fosA).ConclusionRepeated testing on alternate platforms and WGS did not definitively determine the resistance mechanism(s), which in this case, is most likely unstable de-repression of a chromosomal AmpC β-lactamase, porin alterations, or efflux upregulation, with reversion to baseline (non-efflux) transcription. Although sub-culture on specialized media to select for less fit (more resistant) colonies, followed by transcriptome analysis, and multiple sequence alignment, might have revealed the mechanism and better informed the optimal choice of β-lactam, such approaches are neither rapid, nor feasible for hospital laboratories. In this era of escalating drug resistance and dwindling antibiotics, use of the most potent anti-pseudomonals must be balanced with stewardship. Clinicians need access to validated genomic correlates of resistance, and faster, more informative diagnostics. Therefore, we placed these isolates and their sequences in the public domain for inclusion in the Pseudomonas pan-genome and database projects for further countermeasure development.

Compliance with carbapenem guidelines in a university hospital

ObjectiveWe aimed to evaluate carbapenem prescription compliance with guidelines for nosocomial and community-acquired infections. Patients and methodsWe conducted a prospective study over a four-month period at our university hospital. We included all adult and pediatric hospitalized patients who had received at least one dose of carbapenem. Data was collected from patients’ medical records (hard copy and computerized data; CristalLink software). Compliance with guidelines was assessed by two infectious disease specialists. Assessment criteria included indication, antibiotic choice, dosage, and treatment duration. ResultsWe included 152 patients in the study (65.4% of men). Carbapenem prescription was appropriate for 76.3% of prescriptions. The use of carbapenems was considered appropriate for 73.9% of empirical prescriptions and for 77.8% of documented prescriptions. Non-compliance with guidelines was mainly due to prescriptions for community-acquired infections. Antibiotic de-escalation could not be initiated in 40.3% of patients and was only initiated in 51.7% of patients for whom it could be considered. Although the average treatment duration was 7.5 days, 23.7% of patients received carbapenems for more than 10 days. ConclusionThese results highlight the need for a strong carbapenem stewardship program in our hospital.

Carbepenem Stewardship and the Impact on Appropriate Use and Clinical Outcomes

Uncontrolled and excessive use of carbapenem is associated with a higher prevalence of carbapenem resistant Pseudomonas and Acinetobacter isolates. This contributes to poor clinical outcome, a higher rate of mortality and longer hospital stay compared with infections by susceptible isolates. To address the issue of carbapenem resistance, antibiotic monitoring is implemented to reduce consumption and improve appropriate prescribing of carbapenems. The aim of this study is to evaluate whether antibiotic stewardship will be able to improve appropriate carbapenem use and improve clinical outcomes in the local setting. This is a cross-sectional observational study that compares the use of carbapenem during pre-and intervention period. Interventions were carried out by a multidisciplinary antibiotic management team. A total of 143 patients treated with carbapenem were included in this study. A significantly higher rate of overall appropriate carbapenem treatment (pre n=26/79, 40.6% vs. intervention n=48/64, 60.8%, p=0.017) and clinical cure (pre n=34/79, 43% vs. intervention n=46/64, 72%, p=0.001] was identified during the intervention period. There were no significant difference in terms of mortality rate and length of hospitalization. This study suggests that carbapenem stewardship approach is effective in ensuring appropriateness of carbapenem treatment in a tertiary hospital.

Epidemiology and Management of Complicated Urinary Tract Infections (cUTI) in Hospitalized Adults: Opportunities for Carbapenem Stewardship

Epidemiology and Management of Complicated Urinary Tract Infections (cUTI) in Hospitalized Adults: Opportunities for Carbapenem Stewardship

Audit of carbapenem prescriptions comparing 2 assessment periods

ObjectiveThe emergence of extended-spectrum beta-lactamase (ESBL) producing Enterobacteriaceae has resulted in the increase of carbapenem prescriptions. The objective of our study was to determine the appropriateness of carbapenem prescriptions from initiation to reassessment of treatment, between 2009 and 2011. Patients and methodA questionnaire drafted by infectious diseases specialists (IDS) and microbiologists was used to collect clinical and microbiological data concerning carbapenem prescriptions in 2009 and 2011. An IDS then compared the results to assess carbapenem prescription compliance with our hospital's local recommendations. ResultsSeventy-one prescriptions were included in 2009 and 32 in 2011. The carbapenem treatment had been most frequently probabilistic to treat nosocomial infections. The microbiological data revealed that the number of multidrug-resistant (MDR) infections had increased between 2009 and 2011, especially infections involving ESBL-producing Enterobacteriaceae. At treatment reassessment, in 2009 and 2011, 15 (21%) and 12 (38%) carbapenem prescriptions were appropriate and continued. Overall, when comparing the 2 periods, prescriptions complied with local guidelines from initiation to reassessment of treatment without any statistically significant difference (68% in 2009 and 75% in 2011). ConclusionOur study results showed that MDR infections had increased and especially infections due to ESBL-producing Enterobacteriaceae; this was consistent with epidemiological data. We also proved that most carbapenem prescriptions were compliant with recommendations. The increased mobile IDS interventions in medical and surgical departments helped reach this rate of compliance. Carbapenem stewardship may be promoted even in a difficult epidemiological context, especially with IDS interventions for the duration of treatment or at treatment reassessment.

Carbapenem stewardship: does ertapenem affect Pseudomonas susceptibility to other carbapenems? A review of the evidence

The group 2 carbapenems (imipenem, meropenem and, more recently, doripenem) have been a mainstay of treatment for patients with serious hospital infections caused by Pseudomonas aeruginosa, Enterobacteriaceae and other difficult-to-treat Gram-negative pathogens as well as mixed aerobic/anaerobic infections. When ertapenem, a group 1 carbapenem, was introduced, questions were raised about the potential for ertapenem to select for imipenem- and meropenem-resistant Pseudomonas. Results from ten clinical studies evaluating the effect of ertapenem use on the susceptibility of Pseudomonas to carbapenems have uniformly shown that ertapenem use does not result in decreased Pseudomonas susceptibility to these antipseudomonal carbapenems. Here we review these studies evaluating the evidence of how ertapenem use affects P. aeruginosa as well as provide considerations for ertapenem use in the context of institutional stewardship initiatives.

Carbapenem stewardship: positive impact on hospital ecology

Carbapenem stewardship: positive impact on hospital ecology

Carbapenem stewardship – positive impact on hospital ecology

IntroductionExcessive group 2 carbapenem use may result in decreased bacterial susceptibility. ObjectiveWe evaluated the impact of a carbapenem stewardship program, restricting imipenem and meropenem use. MethodsErtapenem was mandated for ESBL-producing Enterobacteriaceae infections in the absence of non-fermenting Gram-negative bacilli (GNB) from April 2006 to March 2008. Group 2 carbapenems were restricted for use against GNB infections susceptible only to carbapenems and suspected GNB infections in unstable patients. Cumulative susceptibility tests were done for nosocomial pathogens before and after restriction using Clinical and Laboratory Standards Institute (CLSI) guidelines. Vitek System or conventional identification methods were performed and susceptibility testing done by disk diffusion according to CLSI. Antibiotic consumption (t-test) and susceptibilities (McNemar's test) were determined. ResultsThe defined daily doses (DDD) of group 2 carbapenems declined from 61.1 to 48.7 DDD/1,000 patient-days two years after ertapenem introduction (p = 0.027). Mean ertapenem consumption after restriction was 31.5 DDD/1,000 patient-days. Following ertapenem introduction no significant susceptibility changes were noticed among Gram-positive cocci. The most prevalent GNB were P. aeruginosa, Klebsiella pneumoniae, and Acinetobacter spp. There was no change in P. aeruginosa susceptibility to carbapenems. Significantly improved P. aeruginosa and K. pneumoniae ciprofloxacin susceptibilities were observed, perhaps due to decreased group 2 carbapenem use. K. pneumoniae susceptibility to trimethoprim-sulfamethoxazole improved. ConclusionPreferential use of ertapenem resulted in reduced group 2 carbapenem use, with a positive impact on P. aeruginosa and K. pneumoniae susceptibility.