Decreasing Antibiotic Resistance Trends Nationally in Gram-Negative Bacteria Across United States Veterans Affairs Medical Centers, 2011–2020

Abstract

Introduction Gram-negative resistance is a well-acknowledged public health threat. Surveillance data can be used to monitor resistance trends and identify strategies to mitigate their threat. The objective of this study was to assess antibiotic resistance trends in Gram-negative bacteria. Methods The first cultures of Pseudomonas aeruginosa , Citrobacter , Escherichia coli , Enterobacter , Klebsiella , Morganella morganii , Proteus mirabilis , and Serratia marcescens per hospitalized patient per month collected from 125 Veterans Affairs Medical Centers (VAMCs) between 2011 to 2020 were included. Time trends of resistance phenotypes (carbapenem, fluoroquinolone, extended-spectrum cephalosporin, multi-drug, and difficult-to-treat) were analyzed with Joinpoint regression to estimate average annual percent changes (AAPC) with 95% confidence intervals and p values. A 2020 antibiogram of reported antibiotic percent susceptibilities was also created to evaluate resistance rates at the beginning of the COVID-19 pandemic. Results Among 40 antimicrobial resistance phenotype trends assessed in 494,593 Gram-negative isolates, there were no noted increases; significant decreases were observed in 87.5% ( n = 35), including in all P. aeruginosa , Citrobacter , Klebsiella , M. morganii , and S. marcescens phenotypes ( p < 0.05). The largest decreases were seen in carbapenem-resistant phenotypes of P. mirabilis , Klebsiella , and M. morganii (AAPCs: − 22.9%, − 20.7%, and − 20.6%, respectively). In 2020, percent susceptibility was over 80% for all organisms tested against aminoglycosides, cefepime, ertapenem, meropenem, ceftazidime-avibactam, ceftolozane-tazobactam, and meropenem-vaborbactam. Conclusion We observed significant decreases in antibiotic resistance for P. aeruginosa and Enterobacterales over the past decade. According to the 2020 antibiogram, in vitro antimicrobial activity was observed for most treatment options. These results may be related to the robust infection control and antimicrobial stewardship programs instituted nationally among VAMCs.

Trends in Empiric Broad-Spectrum Antibiotic Use for Suspected Community-Onset Sepsis in US Hospitals

“…The decrease in culture-positive cases may reflect an increasing tendency to suspect and treat patients for sepsis who turn out not to have sepsis in retrospect. Alternatively, it is possible that community-onset sepsis cases caused by resistant pathogens have truly decreased; indeed, other studies have reported recent declines in community-onset MRSA, Pseudomonas , and Acinetobacter infections . This may reflect the fitness cost of resistance, antibiotic stewardship efforts in both inpatient and outpatient settings, greater attention to hospital infection prevention programs, and changing antibiotic use practices in the environment and in animals .…”

“…Alternatively, it is possible that community-onset sepsis cases caused by resistant pathogens have truly decreased; indeed, other studies have reported recent declines in community-onset MRSA, Pseudomonas , and Acinetobacter infections. 35 , 36 , 37 This may reflect the fitness cost of resistance, antibiotic stewardship efforts in both inpatient and outpatient settings, greater attention to hospital infection prevention programs, and changing antibiotic use practices in the environment and in animals. 38 Notably, increases in multidrug-resistant organisms were observed in US hospitals during the early COVID-19 pandemic era; however, these were primarily driven by hospital-onset rather than community-onset infections.…”

Citrobacter Causing Septic Arthritis: A Case Report

“…[5] There is evidence that Citrobacter possesses intrinsic resistance to carboxypenicillins and aminopenicillins; however, multiple strains have shown at least some degree of susceptibility to piperacillin-tazobactam 92%, cefepime 97.7%, and ceftriaxone 81.6%. [5,7] Additionally, as C. koseri does not harbor the chromosomal AmpC beta-lactamase gene, which decreases the efficacy of the beta-lactam class of antibiotics, it is reasonable to begin empiric ceftriaxone while awaiting formal susceptibility results. [8] While Citrobacter is rarely found to cause septic arthritis, the potential consequences of untreated bacteremia underscore the importance of maintaining a broad differential diagnosis.…”

Structure-based identification of novel inhibitors targeting the enoyl-ACP reductase enzyme of Acinetobacter baumannii

“…The high prevalence of both extreme drug resistant (XDR) and pan drug resistant (PDR) 5 A. baumannii strains poses a challenge for clinical therapeutics. Furthermore, MDR A. baumannii is often associated with inappropriate empiric therapies which contribute to high case fatality rates 6 . Acinetobacter baumannii isolates manifesting XDR are defined as being highly resistant to three or more classes of antibiotics, including fluoroquinolones, penicillins, cephalosporins with inhibitor combinations and aminoglycosides.…”