Molecular epidemiology of bla OXA-23 -producing carbapenem-resistant Acinetobacter baumannii in a single institution over a 65-month period in north China

Abstract

BackgroundCarbapenem-resistant Acinetobacter baumannii poses a significant threat to hospitalized patients, as few therapeutic options remain. Thus, we investigated the molecular epidemiology and mechanism of resistance of carbapenem-resistant A.baumannii isolates in Beijing, China.MethodsCarbapenem-resistant A.baumannii isolates (n = 101) obtained between June 2009 and November 2014 were used. Multilocus sequence typing (MLST) and PCR assays for class C and D β-lactamase were performed on all isolates. S1 nuclease pulsed-field gel electrophoresis (PFGE) and Southern blot hybridization were performed to identify the resistance gene location.ResultsAll 101 A.baumannii isolates were highly resistant to frequently used antimicrobials, and were considered multidrug resistant. A total of 12 sequence types (STs) were identified, including 10 reported STs and 2 novel STs. Eighty-seven isolates were classified to clonal complex 92 (CC92), among which ST191 and ST195 were the most common STs. The bla OXA-23 gene was positive in most (n = 95) of the A.baumannii isolates. Using S1-nuclease digestion PFGE and Southern blot hybridization, 3 patterns of plasmids carrying bla OXA-23 were confirmed. ST191 and ST195 (both harboring bla OXA-23) caused outbreaks during the study period, and this is the first report of outbreaks caused by ST191 and ST195 in north China.Conclusion bla OXA-23-producing A.baumannii ST191 and ST 195 isolates can disseminate in a hospital and are potential nosocomial outbreak strains. Surveillance of imipenem-resistant A.baumannii and antimicrobial stewardship should be strengthened.

<p>Capsule Thickness, Not Biofilm Formation, Gives Rise to Mucoid <em>Acinetobacter baumannii</em> Phenotypes That are More Prevalent in Long-Term Infections: A Study of Clinical Isolates from a Hospital in China</p>

“…The major sequence types (ST) in this study were ST191 and ST195, which were previously reported as the major STs carrying carbapenem-resistance gene bla OXA-23 in the carbapenem-resistance A. baumannii in China. 22 Consistently, all ST191 and ST195 isolates in our study carrying a single copy of bla OXA-23 were shown to be resistant to carbapenem antibiotics. Interestingly, the survival rate of two ST191 isolates (402 and N10) was similar to AB5057, a model highly virulent A. baumannii strain, 23 but the survival rate of six ST195 isolates (401, 405-408, N29) was significantly higher than AB5075 (p < 0.05).…”

Emergence of different Acinetobacter baumannii clones in a Croatian hospital and correlation with antibiotic susceptibility

“…Population structure of the isolates was quite variable with five different STs reported. ST 195 was previously reported in China and associated with OXA-23 β-lactamase in contrast with our study in which this ST was found in OXA-40 positive isolates [46][47] . In both studies ST195 isolates belonged to IC II.…”

Clonal relatedness and resistance characteristics of OXA‐24 and ‐58 producing carbapenem‐resistantAcinetobacter baumanniiisolates in Tehran, Iran

“…While carbapenems have the most extended spectrum of antibacterial activity of all the beta‐lactams, the carbapenem resistance rate in A. baumannii has reached more than 50% worldwide in the past decade as reported in previous studies (Chagas et al ; Wang et al ; Ning et al ; Pfeifer et al ; Rieber et al ). Overall, CRAB isolates are resistant to multiple drugs which forcefully contribute to further outbreaks due to the limited treatment alternatives (Migliavacca et al ; Ning et al ; Rieber et al ). Meanwhile, 100% of our CRAB isolates were MDR and 50% were XDR, which makes the treatment of these isolates difficult; therefore, prescribing carbapenem in combination with other antibiotics, especially aminoglycosides, cephalosporins, colistin, and TG, is recommended for the effective treatment of resistant isolates (Farsiani et al ).…”

“…Of these, OXA‐51 is intrinsic and the acquisition of other CHDL genes occurs through plasmids, integrons, or transposons. In addition to β‐lactamases, increased activity of multidrug efflux pumps, decreased permeability of cell membranes, or modified penicillin‐binding proteins can give rise to the emergence of CRAB strains (Franolić‐Kukina et al ; Amiri et al ; Ning et al ). Meanwhile, insertion sequences (ISs) are mobile genetic elements that can serve as a strong promoter for resistance genes.…”