Molecular detection of genes related to biofilm formation in multidrug-resistant Acinetobacter baumannii isolated from clinical settings

Acinetobacter baumannii is a Gram-negative bacteria associated with hospital-acquired infections. Definitely, antimicrobial resistance and biofilm formation capabilities of clinical isolates have threading potential to persistence in the hospital environment and colonization on medical equipment. Twenty-seven multidrug-resistant clinical isolates were selected from a collection of A. baumannii samples isolated from clinical settings. PCR assays showed the frequencies of genes related to biofilm formation: ompA (100%), bap (30%) and blaPER-1 (44%). Polyclonal antibodies against recombinant AbOmpA8-346 and Bap1-487 proteins were obtained by the mouse immunization method. Western blotting revealed all isolates expressed AbOmpA and only eight isolates were positive for Bap factor. Two strains that had their bap gene disrupted with ISAba125 did not express Bap protein. Our findings showed that all double-negative bap/blaPER-1 isolates were recovered from the bloodstream and had low biofilm formation capabilities, and mostly belonged to type D wrinkled colony morphology. However, clinical isolates extracted from the throats of patients were blaPER-1-positive and had a great capacity to form biofilm, and also mostly belonged to type C wrinkled colony morphology.