title: Development of a protocol for predicting bacterial resistance to microbicides.
abstract: Regulations dealing with microbicides in Europe and the United States are evolving and now require data on the risk of the development of resistance in organisms targeted by microbicidal products. There is no standard protocol to assess the risk of the development of resistance to microbicidal formulations. This study aimed to validate the use of changes in microbicide and antibiotic susceptibility as initial markers for predicting microbicide resistance and cross-resistance to antibiotics. Three industrial isolates (Pseudomonas aeruginosa, Burkholderia cepacia, and Klebsiella pneumoniae) and two Salmonella enterica serovar Typhimurium strains (SL1344 and 14028S) were exposed to a shampoo, a mouthwash, eye makeup remover, and the microbicides contained within these formulations (chlorhexidine digluconate [CHG] and benzalkonium chloride [BZC]) under realistic, in-use conditions. Baseline and postexposure data were compared. No significant increases in the MIC or the minimum bactericidal concentration (MBC) were observed for any strain after exposure to the three formulations. Increases as high as 100-fold in the MICs and MBCs of CHG and BZC for SL1344 and 14028S were observed but were unstable. Changes in antibiotic susceptibility were not clinically significant. The use of MICs and MBCs combined with antibiotic susceptibility profiling and stability testing generated reproducible data that allowed for an initial prediction of the development of resistance to microbicides. These approaches measure characteristics that are directly relevant to the concern over resistance and cross-resistance development following the use of microbicides. These are low-cost, high-throughput techniques, allowing manufacturers to provide to regulatory bodies, promptly and efficiently, data supporting an early assessment of the risk of resistance development.
authors: Cardiff School of Pharmacy and Pharmaceutical Science, Cardiff, Wales, United Kingdom.
authors: Laura
authors: L
authors: Knapp
authors: Unilever Safety and Environmental Assurance Centre, Colworth Science Park, Bedford, United Kingdom.
authors: Alejandro
authors: A
authors: Amézquita
authors: Unilever Safety and Environmental Assurance Centre, Colworth Science Park, Bedford, United Kingdom.
authors: Peter
authors: P
authors: McClure
authors: Unilever Safety and Environmental Assurance Centre, Colworth Science Park, Bedford, United Kingdom.
authors: Sara
authors: S
authors: Stewart
authors: Cardiff School of Pharmacy and Pharmaceutical Science, Cardiff, Wales, United Kingdom maillardj@cardiff.ac.uk.
authors: Jean-Yves
authors: JY
authors: Maillard
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects*; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D016956:Burkholderia cepacia / Q000187:drug effects; D002710:Chlorhexidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003358:Cosmetics / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial; D004755:Enterobacteriaceae / Q000187:drug effects; D008826:Microbial Sensitivity Tests / Q000379:methods*; D011550:Pseudomonas aeruginosa / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D001548:Benzalkonium Compounds; D003358:Cosmetics; C010882:chlorhexidine gluconate; D002710:Chlorhexidine
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