Genomic analysis of Enterobacter cloacae complex from Southern Thailand reveals insights into multidrug resistance genotypes and genetic diversity.

In this study, we conducted a comprehensive investigation into the Enterobacter cloacae complex (ECC), a group of notorious pathogens responsible for various hospital-acquired infections. We aimed to gain critical insights into antimicrobial resistance profiles and genomic diversity among 17 ECC isolates, which were previously collected as part of a short-term surveillance effort for 6 months in 2019. We identified two novel sequence types (ST-1936 in E. bugandensis PSU30 and ST-1937 in E. roggenkampii PSU45) among the 14 distinct STs identified in our ECC isolates. Furthermore, our expanded investigation revealed 296 novel STs within the NCBI Reference Sequence database. We identified six isolates carrying the mcr-9 gene, highlighting a significant concern in antimicrobial resistance (AMR). These genes confer a reduced susceptibility to colistin, a critical last-resort drug for the treatment of multidrug-resistant (MDR) infection. In addition to the AMR complexity, we found that three isolates carried the bla gene on IncN2 plasmids, further emphasizing the urgency of monitoring and managing ECC-related infections. Our study provided evidence of intra-hospital transmission involving E. asburiae isolates PSU37, PSU39, and PSU40, all collected from the nasopharynx of three individuals in the intensive care unit (ICU) of the same hospital. These findings highlight the need for stringent infection control measures to prevent similar outbreaks and emphasize the importance of effective surveillance and management strategies to address ECC-related challenges.