PREVALENCE AND ROLE OF ISABA1 ASSOCIATED WITH BLAOXA-51 AND BLAOXA-23 GENES IN CARBAPENEM-RESISTANT ACINETOBACTER BAUMANNII

Kais Kassim Ghaima*

ABSTRACT

The global spread carbapenem-resistant Acinetobacter baumannii has become a serious problem especially in burn units. The purpose of this study was to detect the association of blaOXA-51 and blaOXA-23 carbapenmase genes with ISAba1 and their effect on carbapenem resistance. To detect insertion sequences ISAba1/blaOXA-23 and ISAba1/blaOXA-51, mapping by PCR using combinations of forward primers ISAba1 and reverse primers of blaOXA-23 and blaOXA-51 were used. A total of 96 isolates of A. baumannii were obtained from burns and wounds infections from Baghdad hospitals, Iraq. Antibiotic sensitivity patterns showed that 70.8% (n=68) of the isolates were resistant to Imipenem and Meropenem, while 13 isolates were susceptible to both antibiotics (13.5%). Of 68 isolates resistant to Imipenem and Meropenem, ISAba1 was detected in 61 isolates (89.7%). 50 isolates carried blaOXA-23 gene, all contained ISAba1 upstream of blaOXA-23 gene, and 41 contained ISAba1 upstream of blaOXA-51 gene. ISAba1 was found upstream of blaOXA-23 only in isolates resistant to carbapenems. Both susceptible and resistant isolates had ISAba1 upstream of blaOXA-51. The ISAba1-activated blaOXA-23 genes were prevalent among the carbapenem-resistant A. baumannii isolates in our hospitals and carbapenems resistance may be due mainly to ISAba1 upstream of blaOXA-23 gene. The present study revealed that the presence of ISAba1/blaOXA-51 in A.baumannii isolates was not contributing in the carbapenems resistance.

Keywords: Acinetobacter baumannii, ISAba1, carbapenems resistance.