Early detection of a possible multidrug-resistant Acinetobacter baumannii outbreak in the local hospital setting by using random amplified polymorphism DNA-polymerase chain reaction (RAPD-PCR), oxacillinase gene profiles, and antibiograms.

Abstract

Background and objectives: Detecting the source of a potential outbreak of multidrug resistant (MDR) Acinetobacter baumannii is necessary to be investigated. This study aimed to detect the possibility of A. baumannii outbreak in a hospital setting using a combination of random amplified polymorphism DNA-polymerase chain reaction (RAPD-PCR), antibiograms, and the presence of oxacillinase genes.

Materials and methods: The antibiogram of 31 clinical isolates and six environmental isolates of A. baumannii were determined by Vitek® 2 Compact. Oxacillinase genes (OXA-23, -24, -51, and -58) were detected by PCR, and RAPD-PCR was conducted using DAF-4 and ERIC-2 primers. The Similarity Index and dendrogram were generated using GelJ v2.3 software.

Results: The antibiograms showed that all MDR A. baumannii isolates has very limited susceptibility to cephalosporins, but mostly susceptible to tigecycline. All isolates were positive for bla _OXA-51-like gene, thirty-two of 37 total isolates (86.5%) were positive for bla _OXA-23-like gene, and none were positive for bla _OXA-24-like and bla _OXA-58-like genes. RAPD-PCR showed that the DAF-4 primer on average had more band visualization and lower Similarity Index's variation compared to the ERIC-2. The discriminatory power of DAF-4 was 0.906. There was a significant correlation between the DAF-4 dendrogram pattern with the antibiogram (r=0.494, p<0.001) and the presence of bla _OXA-23-like gene (r=0.634, p<0.001) from all ICU A isolates. Six out of fourteen ICU A isolates belonged to the same cluster with >95% Similarity Index, while one clinical isolate having an identical dendrogram and antibiogram pattern with an environmental isolate within this cluster.

Conclusion: There is a high probability of MDR A. baumannii outbreak within ICU A detected by multiple analysis of RAPD-PCR, antibiogram and the bla _OXA-23-like gene profiles. This combinatorial approach is conceivable to mitigate possible outbreak situations of A. baumannii in the local hospital without sophisticated microbiology laboratory.