title: Comparative in vitro efficacy of antimicrobial shampoos: a pilot study.
abstract: This study compared the antimicrobial efficacy of shampoos against meticillin-sensitive Staphylococcus pseudintermedius (MSSP), meticillin-resistant S. pseudintermedius (MRSP), antibiotic-sensitive Pseudomonas aeruginosa (PA), multidrug-resistant P. aeruginosa (MDR-PA) and Malassezia pachydermatis. Three isolates were incubated for 10, 30 and 60 min with each shampoo diluted in phosphate-buffered saline. Aliquots were then incubated for 16-18 h on sheep blood agar (bacteria) or for 3 days on Sabouraud's dextrose agar (Malassezia). The minimal bactericidal concentrations (MBCs) for chlorhexidine products (Malaseb(®), Pyoderm(®)/Microbex(®) and Hibiscrub(®)) were 1:1,024-1:2,048 for MSSP and MRSP, 1:512-1:1,024 for PA and MDR-PA, and 1:2,048-1:5,096 for Malassezia at all time points. The MBCs for benzoyl peroxide (Paxcutol(®)) for MSSP and MRSP were 1:2-1:8 at 10 min, and 1:256 after 30 and 60 min. A 1:2 dilution was effective against Pseudomonas, and 1:512-1:1,024 dilutions were effective against Malassezia at all time points. The MBCs for ethyl lactate (Etiderm(®)) for MSSP and MRSP were 1:2 at 10 min, and 1:2-1:16 after 30 and 60 min. A 1:2 dilution was effective against Pseudomonas, and a 1:512 dilution was effective against Malassezia at all time points. Chloroxylenol (Coatex(®)) and acetic acid-boric acid (Malacetic(®)) were not effective against MSSP, MRSP or Pseudomonas. Both were effective against Malassezia at 1:8-1:16 dilution at 10 min, and at 1:8-1:32 dilution after 30 and 60 min. In conclusion, chlorhexidine appeared to be the most effective topical biocide, and MRSP and MDR-PA were no less susceptible than antibiotic-sensitive organisms. These results should, however, be confirmed with larger numbers of isolates.
authors.affiliation: Department of Infection Biology, School of Veterinary Science, The University of Liverpool, Leahurst Campus, Neston, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Young
authors.forename: Laura
authors.initials: L
authors.lastname: Buckley
authors.forename: Neil
authors.initials: N
authors.lastname: McEwan
authors.forename: Tim
authors.initials: T
authors.lastname: Nuttall
mesh_terms: D000818:Animals; D004202:Disinfectants / Q000494:pharmacology*; D004285:Dogs; D024901:Drug Resistance, Multiple, Bacterial; D006203:Hair Preparations / Q000494:pharmacology*; D008290:Malassezia / Q000187:drug effects*; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D010865:Pilot Projects; D011550:Pseudomonas aeruginosa / Q000187:drug effects*; D013210:Staphylococcus / Q000187:drug effects*
chemical_list: D004202:Disinfectants; D006203:Hair Preparations