Early detection of a possible multidrug-resistant Acinetobacter baumannii outbreak in the local hospital setting by...

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.

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.

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.

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.