Emergence of metallo-b-lactamase producing gram-negative bacteria in a hospital with no history of Carbapenem usage in northwest Nigeria

Abstract

Carbapenems are among the antibiotics of last resort against infections caused by antibiotic resistant bacteria. However, resistance to this important class of antibiotic is on the increase due to expression of metallo-betalactamases (MBLs). This study investigated the occurrence of MBL-producing bacteria in a healthcare facility in Sokoto, Nigeria. Swabs were collected from the rectum (n = 29) and bed linens (n = 27) of patients within the surgical wards of the hospital between March and August, 2018 and processed using Centers for Disease Control and Prevention (CDC) broth enrichment method for isolation of carbapenem resistant Gram-negative bacteria (CR-GNB). In addition, 110 bacteria isolated from clinical specimens submitted to microbiology laboratory of the hospital were collected and tested for susceptibility to antibiotics using the disc diffusion method. The carbapenem resistant isolates were further evaluated for MBL-production using the combined disc method. Overall, 31(28.2%) of the Gram-negative bacterial isolates were carbapenem resistant. The most predominant isolated bacterium in this study was E. coli (18; 36%). The isolates were highly resistant to cephalosporins (74%) and fluoroquinolones (52.7%) while remaining moderately susceptible to gentamicin (38.8%) and amoxicillin-clavulanate (45.7 %). Majority of the CR-GNB were extensively drug resistant (19; 38%) and pan drug resistant (10; 20%). The MBL-production test revealed that 19 (38.0%) of the CR-GNB were MBL-positive. The study revealed a high prevalence of MBL-producing CR-GNB in a hospital with no history of its use. This report documents for the first time the independent emergence of such resistance in our hospital. Implementation of adequate antibiotic stewardship program is therefore imperative so as to contain this emerging threat.

Keywords: Carbapenem Resistant Bacteria, Metallo-β-lactamase, Carbapenemase, MDR.