RESUMO
The molecular mechanisms involved in the development of a high level of resistance to a wide range of antimicrobials in Burkholderia pseudomallei and closely related species have not been sufficiently investigated. In the present study, the properties of B. pseudomallei, B. mallei and B. thailandensis mutants with increased resistance to fluoroquinolones and cephalosporins were analysed. Resistance to pefloxacin, ofloxacin and ceftazidime in B. pseudomallei and B. thailandensis was accompanied by an increased resistance to aminoglycosides, beta-lactams, macrolides and chloramphenicol, whereas mutants of B. mallei were characterized by a narrower spectrum of resistance. With the use of the differential display technique, we demonstrated that multiple resistant variants of B. pseudomallei, B. mallei and B. thailandensis had an increased expression of putative efflux transporters belonging to the resistance-nodulation division superfamily and the major facilitator superfamily. With the application of PCR-single-stranded conformational polymorphism (PCR-SSCP) and sequencing, point mutations in gyrA quinolone-resistance determining region were detected in the part of multiple resistant B. pseudomallei and B. mallei mutants. These results indicate that various molecular mechanisms are involved in the development of multiple drug resistance in pathogenic Burkholderia and may be useful for further studying the adaptability of this microorganism and optimization of treatment.
Assuntos
Burkholderia/genética , Resistência Microbiana a Medicamentos/genética , Animais , Antibacterianos/uso terapêutico , Burkholderia/efeitos dos fármacos , Burkholderia/isolamento & purificação , Infecções por Burkholderia/tratamento farmacológico , Burkholderia pseudomallei/efeitos dos fármacos , Burkholderia pseudomallei/genética , Burkholderia pseudomallei/isolamento & purificação , Cefalosporinas/uso terapêutico , Cricetinae , DNA Bacteriano/genética , Fluoroquinolonas/uso terapêutico , Humanos , Dados de Sequência Molecular , Mutação Puntual/genética , Reação em Cadeia da Polimerase , Polimorfismo Conformacional de Fita Simples/genética , Especificidade da EspécieRESUMO
Burkholderia mallei and B. pseudomallei are highly pathogenic microorganisms for both humans and animals. Moreover, they are regarded as potential agents of bioterrorism. Thus, rapid and unequivocal detection and identification of these dangerous pathogens is critical. In the present study, we describe the use of an optimized protocol for the early diagnosis of experimental glanders and melioidosis and for the rapid differentiation and typing of Burkholderia strains. This experience with PCR-based identification methods indicates that single PCR targets (23S and 16S rRNA genes, 16S-23S intergenic region, fliC and type III secretion gene cluster) should be used with caution for identification of B. mallei and B. pseudomallei, and need to be used alongside molecular methods such as gene sequencing. Several molecular typing procedures have been used to identify genetically related B. pseudomallei and B. mallei isolates, including ribotyping, pulsed-field gel electrophoresis and multilocus sequence typing. However, these methods are time consuming and technically challenging for many laboratories. RAPD, variable amplicon typing scheme, Rep-PCR, BOX-PCR and multiple-locus variable-number tandem repeat analysis have been recommended by us for the rapid differentiation of B. mallei and B. pseudomallei strains.
