title: Inflammatory cell infiltration as an indicator of Staphylococcus aureus infection and therapeutic efficacy in experimental mouse mastitis.
abstract: Staphylococcus aureus intramammary colonization of the mouse mammary gland induces migration of polymorphonuclear neutrophils (PMNs) similar to that observed during bovine mastitis. In the present study, a method combining acridine orange staining, fluorescence microscopy and computer-assisted image analysis has been developed to quantitate PMN infiltration in a mouse model of mastitis. This was carried out using paraffin embedded sections, and using this method, we showed that the presence of PMNs increased with the number of bacteria present in tissues. Nearly 400 and 1100 times more PMNs were counted in the mammary gland tissue after 12 and 24 h of infection, respectively, compared to mice infected for 6 h. Treatment with the antibiotic cephapirin at 10 or 25 mg/kg reduced PMN infiltration by 71 and 85%, respectively. In conclusion, this method can be used to quantitate PMN infiltration as a marker of inflammation and bacterial burden in infected tissue sections.
authors.affiliation: Centre d'Etude et de Valorisation de la Diversité Microbienne (CEVDM), Département de Biologie, Faculté des Sciences, Université de Sherbrooke, 2500 Boul, Université, Sherbrooke, Que., Canada, J1K 2R1.
authors.forename: Eric
authors.initials: E
authors.lastname: Brouillette
authors.forename: Gilles
authors.initials: G
authors.lastname: Grondin
authors.forename: Brian G
authors.initials: BG
authors.lastname: Talbot
authors.forename: François
authors.initials: F
authors.lastname: Malouin
mesh_terms: D000165:Acridine Orange / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D002417:Cattle; D002514:Cephapirin / Q000627:therapeutic use; D015169:Colony Count, Microbial / Q000662:veterinary; D004195:Disease Models, Animal; D005260:Female; D005456:Fluorescent Dyes / Q000378:metabolism; D007091:Image Processing, Computer-Assisted; D008321:Mammary Glands, Animal / Q000276:immunology / Q000382:microbiology / Q000473:pathology; D008414:Mastitis, Bovine / Q000276:immunology* / Q000382:microbiology; D051379:Mice; D008856:Microscopy, Fluorescence / Q000662:veterinary; D009504:Neutrophils / Q000276:immunology* / Q000382:microbiology; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000276:immunology* / Q000382:microbiology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000276:immunology; D018709:Statistics, Nonparametric
chemical_list: D000900:Anti-Bacterial Agents; D005456:Fluorescent Dyes; D002514:Cephapirin; D000165:Acridine Orange