title: A 3-year long study of Staphylococcus aureus isolates from subclinical mastitis in three Azawak zebu herds at the Sahelian experimental farm of Toukounous, Niger.
abstract: Staphylococcus (S.) aureus is one of the most important pathogens causing bovine mastitis. The aim of the present work was to follow in three herds and during the 3 years the clonality of S. aureus isolated from California Mastitis Test (CMT)-positive cows at the experimental station of Toukounous (Niger) by (i) comparing their pulsed field gel electrophoresis (PFGE) fingerprints, (ii) identifying their virulotypes by PCR amplification and (iii) assessing the production of capsule and the formation of biofilm. The 88 S. aureus isolates belonged to 14 different pulsotypes, 3 of them being predominant: A (30 %), D (27 %), B (15 %). A and B pulsotypes had the highest profile similarity coefficient (94 %), while others had similarity coefficients under 60 %. Seventy-five S. aureus isolates were further studied for their virulotypes, capsular antigens and biofilm production. Most surface factor-, leukocidin- and haemolysin-, but not the enterotoxin-encoding genes were detected in the majority (>75 %) of the isolates and were evenly distributed between the A, B and D pulsotype isolates. The majority of the 72 S. aureus positive with the cap5H or cap8H PCR produced the CP5 (82 %) or the CP8 (88 %) capsular antigen, respectively. Biofilm production by the 57 icaA-positive isolates was strong for 8 isolates, moderate for 31 isolates but weak for 18 isolates, implying that the icaA gene may not be expressed in vitro by one third of the positive isolates. Similar to other studies, those results confirm that a restricted number of S. aureus clones circulate within the three herds at Toukounous and that their specific virulence-associated properties must still be further studied.
authors.affiliation: Department of Infectious Diseases (Bacteriology), Faculty of Veterinary Medicine and Institute for Fundamental and Applied Research in Animal Health (FARAH), University of Liège, Campus du Sart Tilman (B43a), Quartier Vallée II, Avenue de Cureghem 6, 4000, Liège, Belgium.|Department of Diagnosis, Epidemiological Investigations and Applied Research, Laboratoire Central d'Elevage (LABOCEL), BP 485, Niamey, Niger.
authors.forename: Abdoulkarim Ibrahim
authors.initials: AI
authors.lastname: Issa
authors.affiliation: Department of Infectious Diseases (Bacteriology), Faculty of Veterinary Medicine and Institute for Fundamental and Applied Research in Animal Health (FARAH), University of Liège, Campus du Sart Tilman (B43a), Quartier Vallée II, Avenue de Cureghem 6, 4000, Liège, Belgium.
authors.forename: Jean-Noël
authors.initials: JN
authors.lastname: Duprez
authors.affiliation: Department of Immunology and Infectious Pathology (Microbiology), Interstate School of Veterinary Science and Medicine, BP 5077, Dakar, Senegal.
authors.forename: Rianatou
authors.initials: R
authors.lastname: Bada-Alambedji
authors.affiliation: National School of Public Health, BP 290, Niamey, Niger.
authors.forename: Mamane
authors.initials: M
authors.lastname: Djika
authors.affiliation: Department of Infectious Diseases (Bacteriology), Faculty of Veterinary Medicine and Institute for Fundamental and Applied Research in Animal Health (FARAH), University of Liège, Campus du Sart Tilman (B43a), Quartier Vallée II, Avenue de Cureghem 6, 4000, Liège, Belgium. jg.mainil@ulg.ac.be.
authors.forename: Jacques Georges
authors.initials: JG
authors.lastname: Mainil
authors.affiliation: Department of Infectious Diseases (Bacteriology), Faculty of Veterinary Medicine and Institute for Fundamental and Applied Research in Animal Health (FARAH), University of Liège, Campus du Sart Tilman (B43a), Quartier Vallée II, Avenue de Cureghem 6, 4000, Liège, Belgium.|Present address: Environment & Public Health Research Group, School of Environment & Technology, University of Brighton, Cockcroft Building, Lewes Road, Brighton, BN2 4GJ, UK.
authors.forename: Marjorie
authors.initials: M
authors.lastname: Bardiau
mesh_terms: D000383:Agriculture; D000818:Animals; D015373:Bacterial Typing Techniques / Q000662:veterinary; D002417:Cattle; D002460:Cell Line; D016521:Electrophoresis, Gel, Pulsed-Field / Q000662:veterinary; D005260:Female; D008414:Mastitis, Bovine / Q000453:epidemiology* / Q000382:microbiology; D008892:Milk / Q000382:microbiology; D009548:Niger / Q000453:epidemiology; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000472:pathogenicity*; D014774:Virulence
keywords: Azawak zebu; Mastitis; PCR; Pulsed field gel electrophoresis; Staphylococcus aureus; Virulotyping