Carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii clinical isolates from tertiary care in Nepal

Background: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) and Acinetobacter baumannii (CRAB) were listed on the WHO bacterial priority pathogens list in 2017. These gram-negative bacteria often cause healthcare-associated infections (HAIs), which pose an increasing threat to public health. This study aimed to isolate and identify CRPAs and CRABs from a tertiary care hospital in central Nepal and characterize carbapenem resistance genes at the molecular level. Materials and method s: A total of 59 Pseudomonas aeruginosa ( n =27) and Acinetobacter baumannii ( n =32) isolates were collected from different clinical samples from April 2021 to December 2022. Antibiotic susceptibility was determined via the Kirby disc diffusion method, and the carbapenem inactivation (CIM) method was used for phenotypic confirmation of carbapenem resistance. Conventional polymerase chain reaction (PCR) was used to detect carbapenem resistance genes. Results: Among the 59 isolates, 76.3% were multidrug resistant (MDR), 63.0% were extended-spectrum beta-lactamase (ESBL), and 62.7% were carbapenem resistant. Among the carbapenem-resistant isolates ( n = 37), 75.7% of metallo-beta-lactamase (MBL) producers and 70.3% carried at least one carbapenem resistance gene. The bla _CTX-M gene was predominant among the ESBL-positive isolates, present in 58.8% of the P. aeruginosa isolates and 87.5% of the A. baumannii isolates, whereas 29% of both isolates harbored the bla _TEM gene. Among the CR-PA isolates, 58.3% carried bla _VIM-2 , 16.7% carried bla _NDM-1 , and 8.33% carried bla _OXA-23 . Among the CR-AB isolates, 56% harbored bla _OXA-23 , 32% carried bla _NDM-1 , 16% had both bla _NDM-1 and bla _OXA-23 , and 8% contained both bla _OXA-58 and bla _OXA-23 . Conclusion: This study highlights a significant burden of MDR and carbapenem-resistant P. aeruginosa and A. baumannii , with the co-occurrence of carbapenem resistance genes, in a clinical setting in Nepal. Our findings suggest that active surveillance of antibiotic resistance in pathogens could inform clinicians and healthcare providers about the treatment of infections.