Carbapenem resistance in Pseudomonas aeruginosa and Acinetobacter baumannii in Tanzania

Pseudomonas aeruginosa and Acinetobacter baumannii are notorious hospital-acquired pathogens known for their ability to develop resistance to various antibiotics, including carbapenems, considered a last-line defense. This study investigated the proportion and characteristics of carbapenem resistance in these bacteria among patients at Muhimbili National Hospital, Tanzania. A cross-sectional study was conducted from April to June 2023 at the Muhimbili National Hospital Central Pathology Laboratory: microbiology unit. The study included 950 hospitalized patients whose samples had been sent to the microbiology unit for processing. We used conventional biochemical tests such as oxidase test, triple iron agar, citrate utilization, and urease production for bacterial identification. Antimicrobial susceptibility testing was done using the Kirby-Bauer disk diffusion method. Carbapenemase production in Pseudomonas aeruginosa was detected using the modified carbapenemase inactivation method (mCIM). Of the 950 hospitalized patients, 276 samples had P. aeruginosa (n=179; 64.9%) and A. baumannii (n=97; 35.1%) as bacterial etiologies. Pus swabs (n=90; 32.6%) were the most frequent samples. 140 (50.7%) of the samples were from female patients. Most of the samples, 94 (34.1%), were from patients aged 18-44. Carbapenem resistance was found in 61 (62.9%) of the A. baumannii isolates and 60 (33.5%) of the P. aeruginosa isolates. Of the 60 carbapenem-resistant P. aeruginosa isolates, 35 (58.3%) were carbapenemase producers. The rise of carbapenem resistance poses a danger to treatment options and highlights the need for continuous antimicrobial susceptibility investigations in the future. Given the limited treatment options available, ongoing surveillance is required to establish optimal infection control strategies and select suitable antibiotic medication to minimize the rapid spread of these clinical isolates.