AUTHOR=Li Puyuan , Niu Wen kai , Li Huan , Lei Hong , Liu Wei , Zhao Xiangna , Guo Leijing , Zou Dayang , Yuan Xin , Liu Huiying , Yuan Jing , Bai Changqing 

TITLE=Rapid detection of Acinetobacter baumannii and molecular epidemiology of carbapenem-resistant A. baumannii in two comprehensive hospitals of Beijing, China

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00997

DOI=10.3389/fmicb.2015.00997

ISSN=1664-302X

ABSTRACT=<p><italic>Acinetobacter baumannii</italic> is an important opportunistic pathogen associated with a variety of nosocomial infections. A rapid and sensitive molecular detection in clinical isolates is quite needed for the appropriate therapy and outbreak control of <italic>A. baumannii</italic>. Group 2 carbapenems have been considered the agents of choice for the treatment of multiple drug-resistant <italic>A. baumannii</italic>. But the prevalence of carbapenem-resistant <italic>A. baumannii</italic> (CRAB) has been steadily increasing in recent years. Here, we developed a loop-mediated isothermal amplification (LAMP) assay for the rapid detection of <italic>A. baumannii</italic> in clinical samples by using high-specificity primers of the <italic>bla</italic><sub>OXA-51</sub> gene. Then we investigated the OXA-carbapenemases molecular epidemiology of <italic>A. baumannii</italic> isolates in two comprehensive hospitals in Beijing. The results showed that the LAMP assay could detect target DNA within 60 min at 65°C. The detection limit was 50 pg/μl, which was about 10-fold greater than that of PCR. Furthermore, this method could distinguish <italic>A. baumannii</italic> from the homologous <italic>A. nosocomialis</italic> and <italic>A. pittii</italic>. A total of 228 positive isolates were identified by this LAMP-based method for <italic>A. baumannii</italic> from 335 intensive care unit patients with clinically suspected multi-resistant infections in two hospitals in Beijing. The rates of CRAB are on the rise and are slowly becoming a routine phenotype for <italic>A. baumannii.</italic> Among the CRABs, 92.3% harbored both the <italic>bla</italic><sub>OXA-23</sub> and <italic>bla</italic><sub>OXA-51</sub> genes. Thirty-three pulsotypes were identified by pulsed-field gel electrophoresis, and the majority belonged to clone C. In conclusion, the LAMP method developed for detecting <italic>A. baumannii</italic> was faster and simpler than conventional PCR and has great potential for both point-of-care testing and basic research. We further demonstrated a high distribution of class D carbapenemase-encoding genes, mainly OXA-23, which presents an emerging threat in hospitals in China.</p>