Epidemiological and comparative genomic analyses of Multidrug-Resistant Acinetobacter baumannii collected between 2020 and 2022 in Liaocheng City, Shandong Province, China

Abstract

The emergence and prevalence of multidrug-resistant Acinetobacter baumannii (MRAB) poses a huge challenge to clinical treatment. To investigate the genetic and epidemiologic characteristics of MRAB in Liaocheng, China, and to explore potential resistance mechanisms, 56 MRAB strains were collected from the clinical departments of seven hospitals in Liaocheng between 2020 and 2022. Molecular typing, antimicrobial resistance patterns, and epidemiological characteristics were determined by genome sequencing and comparative genome analysis. Sequence type (ST) 540 was the most prevalent ST of the 56 MRAB in Liaocheng, and most strains (92.86%) were grouped into CC92. Core genome multilocus sequence typing subdivided the strains according to the number of allelic differences and could distinguish different outbreaks caused by ST540 isolates in the hospitals. All the isolates harbored bla_OXA-23 and bla_ADC-25, and at least 92.86% of the isolates were resistant to 10 antibiotics. The major MRAB epidemic clone detected in Liaocheng was ST540, which was different from the results reported in other regions in China. Furthermore, several inter-hospital transmissions of ST540 isolates were observed. The findings highlight the urgent need for effective nosocomial infection control measures and the continuous surveillance of ST540 MRAB in Liaocheng.