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

• Published in: Microbiology spectrum Vol. 10; no. 2; p. e0148521
• Main Authors: Mushtaq, Ammara, Chasan, Rachel, Nowak, Michael D., Rana, Meenakshi, Ilyas, Sahrish, Paniz-Mondolfi, Alberto E., Sordillo, Emilia M., Patel, Gopi, Gitman, Melissa R.
• Format: Journal Article
• Language: English
• Published: United States American Society for Microbiology 27.04.2022
• Subjects: Anti-Bacterial Agents - pharmacology; Anti-Infective Agents; antimicrobial resistance; Bacteriology; beta-Lactam Resistance; beta-Lactamases - genetics; Ceftriaxone; CTX-M; Data Analysis; Enterobacterales; Escherichia coli; Gram-negative bacteria; Gram-Negative Bacteria - genetics; Microbial Sensitivity Tests; rapid molecular diagnostics; Research Article; CTX-M; ceftriaxone; Enterobacterales; Gram-negative bacteria; rapid molecular diagnostics; antimicrobial resistance
• ISSN: 2165-0497; 2165-0497
• DOI: 10.1128/spectrum.01485-21

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. 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.). bla CTX-M was detected in 26.4% Klebsiella pneumoniae , 23.5% Escherichia coli , and 16.4% Proteus mirabilis isolates. As would be expected, both bla CTX-M and bla CTX-M negative isolates were likely to be susceptible to newer agents while bla CTX-M positive isolates were more likely to be resistant to earlier generations of beta-lactam antibiotics. 3/204 bla CTX-M -positive isolates were found to be ceftriaxone-susceptible. Conversely, 2.8% ceftriaxone nonsusceptible strains were negative for all β-lactamase genes on the ePlex BCID-GN panel, including bla CTX-M . The prevalence of CTX-M-producing Enterobacterales remains high in the United States. A small number of bla CTX-M -positive isolates were susceptible to ceftriaxone, and a small number of ceftriaxone nonsusceptible isolates were negative for bla CTX-M . Further studies are needed to determine the optimal management when an isolate is phenotypically susceptible to ceftriaxone, but bla CTX-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.