Abstract

Objectives: Both Enterobacter cloacae and Klebsiella pneumoniae have been regarded as important opportunistic pathogens for humans. Recent data have described the spread of multi-resistant strains of these organisms. Development of novel resistance phenotypes may result in a reduction in anti-infective efficacy, therefore making patient treatment decisions challenging. The Surveillance of Wisconsin Organisms for Trends in Antimicrobial Resistance and Epidemiology (SWOTARE) program aims to combat this issue and improve antibiotic stewardship by monitoring antimicrobial resistance at a local level.

Design: Multi-center laboratory surveillance, with testing at a single location utilizing standardized media and susceptibility testing protocols

Methods: In the years 2018 and 2019, a total of 591 clinically-significant E. cloacae and 668 clinically-significant K. pneumoniae isolates were collected through this initiative; limited demographic data were also supplied. Isolates were tested by broth microdilution procedures advocated by Clinical and Laboratory Standards Institute.

Results: On a statewide level, both E. cloacae and K. pneumoniae demonstrated in vitro potency to carbapenem and aminoglycoside agents at rates exceeding 96%. K. pneumoniae isolates were generally more susceptible to cephem and monobactam agents than E. cloacae isolates; the converse was true for fluoroquinolone agents. Patterns of local antimicrobial resistance were revealed that were not apparent at the state level. E. cloacae isolates submitted from the Northcentral and Southeast regions demonstrated decreased susceptibility to five antimicrobial agents (notably third- and fourth-generation cephems) when compared to the state average. Isolates derived from males, older individuals, and urogenital sources exhibited decreased susceptibility to third- and fourth-generation cephem agents (P ≤ 0.047). With respect to K. pneumoniae, antimicrobial resistance phenotype was not a function of geography or gender. However, isolates emanating from older patients and the respiratory tract showed decreased susceptibility to ampicillin/sulbactam and cefazolin, respectively (P ≤ 0.019).

Conclusions: Antimicrobial resistance surveillance at a local level provides utility to community/rural hospital clinicians, pharmacists, and infection control practitioners. With respect to E. cloacae, further surveillance efforts may be necessary in the Northcentral and Southeast regions of Wisconsin. Subanalysis of demographic data indicated cephem-resistance correlates that are not apparent at the statewide level.