First identification of multidrug-resistant isolates harboring from hospitals in South China.

This study is a first report on the identification of multidrug-resistant (MDR) among non- acinetobacters that had previously escaped automated laboratory detection, and characterize their clinical courses of infection at two tertiary-care hospitals in Shenzhen city, China (2015-2017). Herein, definitive identification by PCR was performed with universal and species-specific primers targeting 16S rDNA and genes, respectively, followed by Sanger sequencing and blast analysis. Antimicrobial susceptibility of isolates was assessed accordingly. Three of the five identified isolates exhibited carbapenem-resistance and were subjected to a multiplex PCR assay to detect drug-resistance genes. Sequences of the amplicon were aligned with curated sequences from global databases for phylogenetic analysis on evolutionary relations. Five clinical isolates of were thereby re-identified, whose infections were primarily nosocomial. Automated identification and susceptibility testing systems (Phoenix-100 and VITEK 2) proved insufficient for discriminating from other acinetobacters such as and . Among these isolates, three exhibited carbapenem-resistant phenotypes indistinguishable from that of carbapenem-resistant . The carbapenem-resistant isolates were subsequently confirmed to carry a (New Delhi metallo--lactamase-1) gene downstream of IS. Phylogenetic analysis revealed that isolates evolved slowly but independently in local habitats. isolates are difficult to distinguish by traditional automated detection systems. PCR-based identification via amplification and sequencing of selected house-keeping genes provides sufficient resolution for discriminating the isolates.