Emergence of carbapenem-resistant Acinetobacter nosocomialis strain ST410 harbouring plasmid-borne blaOXA-72 gene in Taiwan

Abstract

Letter to the Editor Emergence of carbapenem-resistant Acinetobacter nosocomialis strain ST410 harbouring plasmid-borne bla OXA-72 gene in Taiwan Acinetobacter nosocomialis is increasingly identified as a causative agent of nosocomial infections in recent years [1]. Carbapenems, especially imipenem, is often used as the drug of choice for treating multidrug-resistant Gram-negative bacterial infection, but the carbapenem-nonsusceptible rate of the Acinetobacter species is increasing worldwide. The Ambler class B-metallo-b-lactamases and carbapenem-hydrolyzing class D b-lactamases (CHDLs) are two common mechanisms for the imipenem nonsusceptibility of Acinetobacter species [2]. CHDLs are most strongly associated with imipenem nonsusceptibility of Acinetobacter species. Acinetobacter baumannii and A. nosocomialis, the two most common species, together account for >80% of all Acinetobacter infections in Taiwan. The imipenem-nonsusceptible rate of A. nosocomialis in bloodstream infections increased in recent years. However, the mechanism of imipenem-nonsusceptible A. nosocomialis is rarely reported [1]. The aim of this study was to investigate the mechanism and molecular epidemiology of imipenem-nonsusceptible A. nosocomialis isolated from bloodstream infections in Taiwan. In this retrospectively study, we analysed a total collection of 111 nonduplicate A. nosocomialis of bloodstream infections in Tri-Service General Hospital, National Defense Medical Center, Taiwan, from 2012 April to 2016 June. All isolates were identified using the VITEK 2 system (bioM erieux, Marcy l' Etoile, France) and were confirmed by sequencing of the 16Se23S rRNA intergenic transcribed spacer region and rpoB gene. Antimicrobial susceptibility tests were performed by the VITEK 2 system. The MIC values (mg/L) of imipenem were determined by both the agar dilution method and the Etest (AB Biodisk, Solna, Sweden). All isolates were nonsusceptible to ampicillin, cefazolin and ceftriaxone. Their nonsusceptible rates of piperacillin/tazobactam, imipenem, ciprofloxacin, cefepime, gentamicin and tigecycline ranged 27% to 40.5%. In contrast, more than 92.8% of the isolates were susceptible to amikacin. Comparison of the susceptibility patterns between isolates from the intensive care unit (ICU) and the non-ICU, A. nosocomialis strains isolated from ICU showed significantly higher resistance rates to piperacillin/tazobactam, imipenem, ciprofloxacin, cefepime, gentamicin and tigecycline than those isolated from general wards (Fisher's exact test, p <0.05). Using the Clinical and Laboratory Standards Institute breakpoints for Acinetobacter species (susceptible, 2 mg/L; intermediate, 4 mg/L; resistant, 8 mg/L), 41 isolates were nonsusceptible to imipenem, including 37 isolates with MIC >16 mg/L, three isolates with MIC of 8 mg/L and one isolate with MIC of 4 mg/L. The remaining 70 (63.1%) of 111 isolates were imipenem susceptible. Contents lists available at ScienceDirect Clinical Microbiology and Infection j o u r n a l h o m e p a g e : w w w. c l i n i ...

AdeABC Efflux Pump Controlled by AdeRS Two Component System Conferring Resistance to Tigecycline, Omadacycline and Eravacycline in Clinical Carbapenem Resistant Acinetobacter nosocomialis

“…Further studies confirmed that AdeRS TCS played a role in the resistance to the three antibiotics in A. nosocomialis. ST410 was found to be the most dominant type in clinical Tn-CRAn isolates in Taiwan, which is consistent with our previous studies (Chen et al, 2018;Yang et al, 2019). This may indicate that there is an unknown mechanism in ST410 that provides fitness advantage in a hospital setting, which could easily transform to carbapenem and/or tigecycline resistance.…”

“…Acinetobacter nosocomialis is an emerging opportunistic pathogen that is usually grouped into the Acinetobacter calcoaceticus-baumannii complex (Acb complex) (Vijayakumar et al, 2019). In Asia, the carbapenem resistant rate among infections caused by A. nosocomialis is as high as 30% (Chen et al, 2018;Singkham-In and Chatsuwan, 2018;Chen et al, 2019). Tigecycline has been regarded as one of the final armamentaria against carbapenem resistant A. nosocomialis (CRAn).…”

Molecular Epidemiology of Emerging Carbapenem Resistance in Acinetobacter nosocomialis and Acinetobacter pittii in Taiwan, 2010 to 2014

“…Plasmid pAB-NCGM253, which carries bla OXA-72 , was recently identified in carbapenem-resistant A. nosocomialis isolates in Taiwan (20). PCR mapping showed that all seven A.…”

Rapid typing of carbapenem-resistant Acinetobacter baumannii and Acinetobacter nosocomialis by multiplex Pan- and OXA-PCR assays

“…ST410 was first registered in the MLST database as CRAN in 2012. In our previous research [22], Pasteur ST410 was demonstrated to carry plasmid-borne bla OXA-72 ( bla OXA-24 subgroup). In this study, we found that these CRAN ST410 isolates carrying the bla OXA-24 subgroup gene were mainly Oxford ST1997.…”