Antibiotic resistance patterns and SDS-PAGE protein profiles of Burkholderia cepacia complex isolates from nosocomial and environmental sources in Venezuela

Abstract

Background: Antibiotic resistance and SDS-PAGE protein patterns were determined in nosocomial and environmental isolates of the Burkholderia cepacia complex to assess similarities between them and to identify common protein bands that could be associated with resistance to certain antimicrobial agents.

Material/methods: Antibiotic resistance patterns were determined by the disk diffusion method on Mueller-Hinton medium and minimum inhibitory concentrations were obtained by the dilution method on agar. Electrophoresis of whole-cell protein extracts and purified external membrane proteins were performed by SDS-PAGE. Based on resistance to nine antibiotics and the presence or absence of specific protein bands, dendrograms were constructed by the unweighted pair-group using the average linkage clustering method.

Results: Both environmental and nosocomial Bcc isolates showed resistance to multiple antibiotics; however, clinical isolates demonstrated two times higher resistance levels than environmental isolates. The Dice index similarity coefficients between environmental and nosocomial strains ranged from 72% to 91.4%. Comparative analysis between common protein bands and antibiotic resistance patterns revealed close association of Mr 135, 76, 72, 53, and 50 kDa with imipenem and aztreonam, Mr 53 and 31 kDa with trimethoprim/sulfamethoxazole, and Mr 50 kDa with ceftazidime resistance.

Conclusions: 1. The environmental and nosocomial Bcc isolates showed a high degree of similarity in their protein profiles. 2. Three common protein bands, i.e. Mr of 31, 50, and 53 kDa, detected in the Bcc isolates from both clinical and natural sources could be associated with resistance to the antimicrobial agents trimethoprim/sulfamethoxazole, ceftazidime, and aztreonam, respectively.