title: Persistence of a Staphylococcus aureus small-colony variant under antibiotic pressure in vivo.
abstract: Staphylococcus aureus small-colony variants (SCVs) have been implicated in chronic and persistent infections. Bovine mastitis induced by S. aureus is an example of an infection difficult to eradicate by conventional antimicrobial therapies. In this study, the ability to colonize mouse mammary glands and persist under antibiotic treatment was assessed for S. aureus Newbould and an isogenic hemB mutant, which exhibited the classical SCV phenotype. The hemB mutant showed a markedly reduced capacity to colonize tissues. However, although the hemB mutant was as susceptible as S. aureus Newbould to cephapirin in vitro, it was over a 100 times more persistent than the parental strain in the mammary glands when 1 or 2 mg kg(-1) doses were administrated. These results suggest that, although the hemB mutant has a reduced ability to colonize mammary glands, the SCV phenotype may account for the persistence of S. aureus under antibiotic pressure in vivo.
authors.affiliation: Centre d'Etude et de Valorisation de la Diversité Microbienne (CEVDM), Département de biologie, Université de Sherbrooke, Sherbrooke, Que., Canada J1K 2R1.
authors.forename: Eric
authors.initials: E
authors.lastname: Brouillette
authors.forename: Alejandro
authors.initials: A
authors.lastname: Martinez
authors.forename: Bobbi J
authors.initials: BJ
authors.lastname: Boyll
authors.forename: Norris E
authors.initials: NE
authors.lastname: Allen
authors.forename: François
authors.initials: F
authors.lastname: Malouin
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology* / Q000627:therapeutic use; D002417:Cattle; D002478:Cells, Cultured; D002514:Cephapirin / Q000494:pharmacology / Q000627:therapeutic use; D003001:Cloning, Molecular; D015169:Colony Count, Microbial; D004195:Disease Models, Animal; D024881:Drug Resistance, Bacterial; D005260:Female; D005839:Gentamicins / Q000494:pharmacology; D006427:Hemin / Q000378:metabolism; D008321:Mammary Glands, Animal / Q000382:microbiology*; D008413:Mastitis / Q000382:microbiology / Q000662:veterinary*; D008414:Mastitis, Bovine / Q000382:microbiology; D051379:Mice; D010957:Plasmids; D013203:Staphylococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D014774:Virulence
chemical_list: D000900:Anti-Bacterial Agents; D005839:Gentamicins; D006427:Hemin; D002514:Cephapirin