The emergence of Acinetobacter baumannii ST-6 multidrug resistant: A resilient biofilm producer, Malaysia

ABSTRACT

Aims: The aim of this research is to explore the presence of multidrug-resistance (MDR) Acinetobacter baumannii strains isolated from hospitalized patients in a tertiary-care center, Subang Jaya, Selangor, Malaysia and to compare their genotypic and phenotypic characteristics. Methodology and results: Clonal relationships were determined by multilocus sequence typing (MLST) and biofilm forming ability was evaluated by using 2, 3 - bis (2 - methoxy - 4 - nitro - 5-sulfophenyl) - 5 - [(phenylamino) carbonyl] - 2H-tetrazolium hydroxide (XTT) reduction assay in microplates and Congo red agar method (CRA). Four virulence genes coding for A. baumannii pilus usher-chaperone assembly protein, csuE gene; outer membrane protein, ompA gene; biofilm poly-β-1, 6-Nacetylglucosamine (PNAG) synthesis protein, pgaA gene; and acinetobactin-mediated iron acquisition protein, bauA gene were searched for in a collection of strains. Antimicrobial resistance against 11 antibiotics were studied by broth microdilution method. Seventeen A. baumannii clinical strains were isolated and MLST showed that the strains belonged to 5 distinct sequence types (STs), namely, ST-6, ST-265, ST-324, ST-325 and ST-432. Fiftythree percent of the strains were resistant to 4 or more antibiotics. Twelve strains produced biofilm and out of them, 4 were strong biofilm producer, besides, these strong biofilm producers were MDR strains and belongs to ST-6. In addition, all strains were ompA positive, biofilm producing strains were csuE and pgaA positive and only strong biofilm producing strains were bauA positive. Conclusion, significance and impact study Our study demonstrates that the ST-6 strains in Malaysia could represent MDR, capable of forming strong biofilm and possess csuE, ompA, pgaA and bauA genes, virulence characteristics that probably help the bacteria to persist and cause infection.