title: Key role for efflux in the preservative susceptibility and adaptive resistance of Burkholderia cepacia complex bacteria.
abstract: Bacteria from the Burkholderia cepacia complex (Bcc) are encountered as industrial contaminants, and little is known about the species involved or their mechanisms of preservative resistance. Multilocus sequence typing (MLST) revealed that multiple Bcc species may cause contamination, with B. lata (n = 17) and B. cenocepacia (n = 11) dominant within the collection examined. At the strain level, 11 of the 31 industrial sequence types identified had also been recovered from either natural environments or clinical infections. Minimal inhibitory (MIC) and minimum bactericidal (MBC) preservative concentrations varied across 83 selected Bcc strains, with industrial strains demonstrating increased tolerance for dimethylol dimethyl hydantoin (DMDMH). Benzisothiazolinone (BIT), DMDMH, methylisothiazolinone (MIT), a blend of 3:1 methylisothiazolinone-chloromethylisothiazolinone (M-CMIT), methyl paraben (MP), and phenoxyethanol (PH), were all effective anti-Bcc preservatives; benzethonium chloride (BC) and sodium benzoate (SB) were least effective. Since B. lata was the dominant industrial Bcc species, the type strain, 383(T) (LMG 22485(T)), was used to study preservative tolerance. Strain 383 developed stable preservative tolerance for M-CMIT, MIT, BIT, and BC, which resulted in preservative cross-resistance and altered antibiotic susceptibility, motility, and biofilm formation. Transcriptomic analysis of the B. lata 383 M-CMIT-adapted strain demonstrated that efflux played a key role in its M-CMIT tolerance and elevated fluoroquinolone resistance. The role of efflux was corroborated using the inhibitor l-Phe-Arg-β-napthylamide, which reduced the MICs of M-CMIT and ciprofloxacin. In summary, intrinsic preservative tolerance and stable adaptive changes, such as enhanced efflux, play a role in the ability of Bcc bacteria to cause industrial contamination.
authors.affiliation: Cardiff School of Biosciences, Cardiff University, Cardiff, United Kingdom.
authors.forename: Laura
authors.initials: L
authors.lastname: Rushton
authors.forename: Andrea
authors.initials: A
authors.lastname: Sass
authors.forename: Adam
authors.initials: A
authors.lastname: Baldwin
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Dowson
authors.forename: Denise
authors.initials: D
authors.lastname: Donoghue
authors.forename: Eshwar
authors.initials: E
authors.lastname: Mahenthiralingam
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D015373:Bacterial Typing Techniques; D001483:Base Sequence; D001558:Benzethonium / Q000494:pharmacology; D018441:Biofilms / Q000254:growth & development; D019121:Burkholderia Infections / Q000382:microbiology; D042602:Burkholderia cepacia complex / Q000187:drug effects* / Q000235:genetics*; D026942:DNA Topoisomerases / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D005026:Ethylene Glycols / Q000494:pharmacology; D024841:Fluoroquinolones / Q000494:pharmacology; D006801:Humans; D006827:Hydantoins / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D058885:Multilocus Sequence Typing; D016272:Occupational Health; D010226:Parabens / Q000494:pharmacology; D011310:Preservatives, Pharmaceutical / Q000494:pharmacology*; D017422:Sequence Analysis, DNA; D020160:Sodium Benzoate / Q000494:pharmacology; D013844:Thiazoles / Q000494:pharmacology
chemical_list: D001426:Bacterial Proteins; D005026:Ethylene Glycols; D024841:Fluoroquinolones; D006827:Hydantoins; D010226:Parabens; D011310:Preservatives, Pharmaceutical; D013844:Thiazoles; D001558:Benzethonium; C015358:methylparaben; D026942:DNA Topoisomerases; C005398:phenoxyethanol; C015699:1,2-benzisothiazoline-3-one; D020160:Sodium Benzoate