The Prevalence of Carbapenem and Colistin-Resistant Gram-Negative Bacteria Isolated from Hospital-Admitted Patients with Bacteremia

Carbapenem-resistance, a global health concern augmented with resistance against last-resort antibiotic colistin has become a great challenge. Bacteremia caused by Carbapenem-resistant (CR) Gram-negative bacteria (GNB) has been linked to prolonged hospitalization and high mortality. Colistin-resistant Acinetobacter baumannii (CoRAB) represent a serious threat to patients admitted to Intensive Care Unit (ICU) with mortality estimates up to 100%. This study aimed to estimate the current burden of CR and CoR GNB in admitted patients. In this prospective study, a total of 21,600 blood cultures were processed in automated BACTEC system. Conventional methods and Automated Profile Index (API) 20E and 20NE were used for GNB identification. Carbapenem and colistin Antimicrobial Susceptibility Testing (AST) was determined using disc-diffusion and broth microdilution (BMD) methods respectively. The pooled CR was 25.59%. CR was highest in Klebsiella spp. (44.2%) and Acinetobacter baumannii (34.66%). The overall CoR among 2903 GNB was 0.96% while among 743 CR-GNB was 3.76%. CoR rates are lower in Sindh compared to Punjab. CoR has reached up to 5.20% in Klebsiella spp. and up to 3.8% in A. baumannii. All Pseudomonas aeruginosa isolates were sensitive to colistin. Significant proportion of CoRKP and CoRAB in ICU alarms the situation and calls for to seek ways to minimize the emergence of CoR. Klebsiella spp. and A. baumannii remain the predominant CR and CoR GNB in Bloodstream infections (BSI). Presence of CoR-E. coli in pediatric wards highlight the poor hygienic practices and fecal transmission.