Carbapenem-Resistant Gram-Negative Bacilli Characterization in a Tertiary Care Center from El Bajio, Mexico

Carbapenem-resistant Gram-negative bacilli (CR-GNB) are a major public health concern. We aimed to evaluate the prevalence of CR-GNB and the frequency of carbapenemase-encoding genes in a tertiary referral center from El Bajio, Mexico. A cross-sectional study was conducted between January and October 2022; Gram-negative bacilli (GNB) were screened for in vitro resistance to at least one carbapenem. CR-GNB were further analyzed for carbapenemase-production through phenotypical methods and by real-time PCR for the following genes: , , , , , and . In total, 37 out of 508 GNB were carbapenem-resistant (7.3%, 95% CI 5.2-9.9). Non-fermenters had higher rates of carbapenem resistance than (32.5% vs. 2.6%; OR 18.3, 95% CI 8.5-39, < 0.0001), and showed higher carbapenem resistance than other (27% vs. 1.4%; OR 25.9, 95% CI 6.9-95, < 0.0001). Only 15 (40.5%) CR-GNB had a carbapenemase-encoding gene; were more likely to have a carbapenemase-encoding gene than non-fermenters (63.6% vs. 30.8%, = 0.08); and were the main genes found in ; and was the most common for . The gene was harbored in one polymyxin-resistant . In our setting, NDM was the most common carbapenemase; however, less than half of the CR-GNB showed a carbapenemase-encoding gene.