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

Abstract

Acinetobacter baumannii 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 A. baumannii. Group 2 carbapenems have been considered the agents of choice for the treatment of multiple drug-resistant A. baumannii. But the prevalence of carbapenem-resistant A. baumannii (CRAB) has been steadily increasing in recent years. Here, we developed a loop-mediated isothermal amplification (LAMP) assay for the rapid detection of A. baumannii in clinical samples by using high-specificity primers of the blaOXA-51 gene. Then we investigated the OXA-carbapenemases molecular epidemiology of A. baumannii 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 A. baumannii from the homologous A. nosocomialis and A. pittii. A total of 228 positive isolates were identified by this LAMP-based method for A. baumannii 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 A. baumannii. Among the CRABs, 92.3% harbored both the blaOXA-23 and blaOXA-51 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 A. baumannii 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.

Molecular epidemiology and antimicrobial resistance features of Acinetobacter baumannii clinical isolates from Pakistan

“…Overall, our results were in line with previous studies nominating OXA-23 as the most commonly detected group of acquired Class D β-lactamases in A. baumannii both in the region and throughout the world [49][50][51]. The occurrence of ISAba1 upstream of bla OXA-23 , bla OXA-66 , ampC-2, ampC -3, ampC-8, ampC-19, ampC-20, ampC-78, or ampC-79 has the potential to overexpress these genes, which might subsequently confer resistance to carbapenems (bla OXA ) or ceftazidime (ampC) as previously proposed [48,52,53].…”

Surveillance of Dihydropteroate Synthase Genes in Stenotrophomonas maltophilia by LAMP: Implications for Infection Control and Initial Therapy

“…The LAMP detection method has several advantages over traditional PCR as a tool for use in epidemiological surveys. First, LAMP is generally less time- and labor-intensive, and it proceeds under an isothermal condition within 60 min (Notomi et al, 2000; Dong et al, 2015a; Li et al, 2015). Second, LAMP is more cost-efficient than conventional PCR, since it only requires access to a constant-temperature apparatus, such as a common laboratory water bath.…”

High distribution of 16S rRNA methylase genes rmtB and armA among Enterobacter cloacae strains isolated from an Ahvaz teaching hospital, Iran

“…The whole genome was extracted using boiling method as described previously [16]. In addition, the extraction of plasmid DNA was performed using a Plasmid Purification Kit (CinnaGene, Iran) according to manufacturer's procedure.…”