Affiliation:
1. Department of Medical Microbiology, Başkent University Faculty of Medicine, Ankara, Turkey
Abstract
Introduction. Extended-spectrum β-lactamase (ESBL)-producing
Enterobacteriaceae
and carbapenem-resistant
Enterobacteriaceae
are characterized by the World Health Organization as pathogens for which new antibiotics are urgently needed. Omadacycline and eravacycline are two novel antibacterials within the tetracycline class.
Gap Statement. There are limited data regarding the comparison of the activities of omadacycline, eravacycline and tigecycline against K. pneumoniae isolates with different antimicrobial susceptibility profiles.
Aim. Our objective was to compare the in vitro activities of omadacycline, eravacycline and tigecycline against a collection of K. pneumoniae isolates, including non-ESBL-producing, ESBL-producing and carbapenem-resistant strains.
Methodology. Ninety-four K. pneumoniae isolates, including 30 non-ESBL-producing, 30 ESBL-producing and 34 carbapenem-resistant (22 carrying bla
OXA-48, 12 carrying bla
NDM) strains were included in the study. ESBL and carbapenemase genes were detected by conventional PCR. Omadacycline, eravacycline and tigecycline MICs were determined by the gradient diffusion method and interpreted using US Food and Drug Administration (FDA)-defined breakpoints.
Results. Overall, the percentage of tigecycline-susceptible strains (97.9 %) was higher than the percentage of omadacyline-susceptible (75.5 %) and eravacycline-susceptible (72.3 %) strains. The omadacycline and eravacycline susceptibility rates were 83.3 % among non-ESBL-producing isolates and 66.7 % among ESBL-producing isolates. The most common ESBL gene detected was blaCTX
-M (90 %), followed by bla
TEM (50 %) and bla
SHV (50 %). The omadacycline and eravacycline susceptibility rate among isolates carrying bla
TEM was 33.3 %, whereas it was 100 % among isolates that do not carry bla
TEM. The omadacycline and eravacycline susceptibility rates among carbapenem-resistant isolates were 76.5 and 67.6 %, respectively. The omadacycline susceptibility rates among bla
OXA-48-positive and bla
NDM-positive isolates were 77.3 and 75.0 %, respectively. The eravacycline susceptibility rates among bla
OXA-48-positive and bla
NDM-positive isolates were 68.2 and 66.7 %, respectively. One carbapenem-resistant isolate was intermediate and one ESBL-producing isolate was resistant to tigecycline.
Conclusion. Overall, tigecycline was the most active tetracycline against isolates. Omadacycline and eravacycline showed excellent activity against ESBL-producing K. pneumoniae isolates that do not carry bla
TEM. Omadacycline showed reasonable activity against carbapenem-resistant K. pneumoniae isolates carrying bla
OXA-48 or bla
NDM.
Subject
Microbiology (medical),General Medicine,Microbiology