Correlation between Identification of b-Lactamase Resistance Genes and Antimicrobial Susceptibility Profiles in Gram-Negative Bacteria: a Laboratory Data Analysis

Ammara Mushtaq, Rachel Chasan, Michael D. Nowak, Meenakshi Rana, Sahrish Ilyas, Alberto E. Paniz-Mondolfi, Emilia M. Sordillo, Gopi Patel, Melissa R. Gitman

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

We reported the frequency of resistance gene detection in Gram-negative blood culture isolates and correlated these findings with corresponding antibiograms. Data were obtained from 1045 isolates tested on the GenMark Dx ePlex Blood Culture Identification Gram-Negative Panels at the Mount Sinai Hospital Clinical Microbiology Laboratory in New York from March 2019 to February 2021. Susceptibilities were performed using Vitek 2 (bioMérieux Clinical Diagnostics) or Microscan (Beckman Coulter Inc.). blaCTX-M was detected in 26.4% Klebsiella pneumoniae, 23.5% Escherichia coli, and 16.4% Proteus mirabilis isolates. As would be expected, both blaCTX-M and blaCTX-M negative isolates were likely to be susceptible to newer agents while blaCTX-M positive isolates were more likely to be resistant to earlier generations of beta-lactam antibiotics. 3/204 blaCTX-M-positive isolates were found to be ceftriaxone-susceptible. Conversely, 2.8% ceftriaxone nonsusceptible strains were negative for all b-lactamase genes on the ePlex BCID-GN panel, including blaCTX-M. The prevalence of CTX-M-producing Enterobacterales remains high in the United States. A small number of blaCTX-M-positive isolates were susceptible to ceftriaxone, and a small number of ceftriaxone nonsusceptible isolates were negative for blaCTX-M. Further studies are needed to determine the optimal management when an isolate is phenotypically susceptible to ceftriaxone, but blaCTX-M is detected. IMPORTANCE There is limited literature on corresponding results obtained from rapid molecular diagnostics with the antibiotic susceptibility profile. We reported a correlation between the results obtained from ePlex and the antibiograms against a large collection of Gram-negative bacteria. We reported that there can be a discrepancy in a small number of cases, but the clinical significance of that is unknown.

Original languageEnglish
JournalMicrobiology spectrum
Volume10
Issue number2
DOIs
StatePublished - Apr 2022

Keywords

  • CTX-M
  • Enterobacterales
  • Gram-negative bacteria
  • antimicrobial resistance
  • ceftriaxone
  • rapid molecular diagnostics

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