Comparative analysis of Acinetobacter baumannii isolated from hospital wastewater & community tap water: investigating antibiotic resistance and AMR genes

Abstract

Antibiotic resistant Acinetobacter baumannii (A. baumannii) has emerged as important nosocomial pathogen associated with various infections in clinical settings. It has the ability to persist in the environment for prolonged periods of time due to the wide range of antibiotic resistance factors it possesses. A. baumannii represents a global threat owing to its ability to resist most of the currently available antimicrobial agents. Hospital wastewater is considered to be one of the main reservoirs for antibiotic resistance because they create a system where antibiotic resistance (AMR) genes can be shared. Our study was performed to assess and analyse A. baumannii isolated from the wastewater of 3 selected hospitals and tapwater of houses surrounding the hospitals in order to create a profile of the antibiogram and antibiotic resistance genes of A. baumannii found from these environmental niches. 37 samples were collected from the sampling sites from March 2023 to June 2023 analysed presumptively by culture-dependent methods. A total of 100 isolates were confirmed to be A. baumannii by detection of the blaOXA-51-like gene. 52 representative isolates were undergone Antibiotic Susceptibility Testing and the highest antibiotic resistance profile was seen against Cefixime (100%), Ceftazidime (96.1%) and Aztreonam (84.6%). 100% of the isolates were seen to be multi-drug resistant (resistant to at least 3 antibiotics). Molecular screening of 6 beta-lactamase encoding genes was performed. Among the investigated genes, only the prevalence of blaNDM-1 was found in 5 isolates- 4 from hospital wastewater source and 1 from community tap water source. blaCTX-M, blaSHV, blaTEM, blaOXA-48, blaIMP were not detected in any of the studied isolates. 37.6% of imipenem resistant isolates showed the presence of blaNDM-1. The findings of our study revealed the availability of NDM-1 producing Acinetobacter baumannii strains in the environment setting. It can be expected that these antibiotic resistant genes would spread from hospitals via the untreated sewage effluents and disseminate to our supply water which is a threat for public health.