High-level resistance to fluoroquinolones and cephalosporins in Burkholderia pseudomallei and closely related species

Abstract

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.

Within-Host Evolution of Burkholderia pseudomallei during Chronic Infection of Seven Australasian Cystic Fibrosis Patients

“…Our genomic analysis revealed that a Y77S amino acid change in DNA gyrase subunit A (GyrA) is a putative mechanism for this ciprofloxacin resistance. Using stepwise fluoroquinolone selection of B. pseudomallei laboratory mutants, Viktorov and colleagues observed GyrA mutations T83I, G81C, and D87Y in resistant strains (48). Thus, ciprofloxacin resistance in B. pseudomallei is likely encoded by multiple missense gyrA mutations, and here we show that the Y77S mutation may also confer ciprofloxacin resistance, although functional confirmation of its role was not part of the present study.…”

Antibiotic resistance in Burkholderia species

“…In E. coli roughly 50% of mutations affect Ser83 (Yoshida et al, 1990). In B. pseudomallei , all in vitro selected fluoroquinolone resistant mutants contained a Thr83Ile mutation (Viktorov et al, 2008). This is consistent with the finding that most Burkholderia species contain a GyrA Thr83 instead of the Ser83 found in other bacteria (Winsor et al, 2008).…”

Antimicrobial and antibiofilm activity of LL-37 and its truncated variants against Burkholderia pseudomallei

“…Further investigation of a library of LL-37 fragments with overlapping sequences using Burkholderia thailandensis E264 as a model demonstrated that LL-31, a truncated variant of LL-37 missing the six residues at the C-terminus, displayed the strongest killing effect against B. thailandensis E264 by disrupting the bacterial membrane and subsequent leakage of intracellular components leading to death of the bacterium [13]. Although B. thailandensis is closely related to B. pseudomallei [14], susceptibility to antimicrobial agents differs [15]. Therefore, in the present study, a library of LL-37 fragments was further investigated with B. pseudomallei both in planktonic and biofilm form in comparison with the conventional antibiotic CAZ.…”