Phenotypic characterization of Staphylococci causing mastitis in goats and microarray-based genotyping of Staphylococcus aureus isolates

Abstract

To understand the prevalence and characteristics of Staphylococci causing goat mastitis in Algeria, mastitis milk samples were collected and cultured on both blood agar and mannitol salt agar medium. Staphylococci isolates were identified by API-Staph gallery and tested for antibiotic susceptibility by disk diffusion method. DNA microarrays analysis was performed on S. aureus strains in order to detect virulence factors, including toxins, and to assign the isolates to theirs MLST clonal complexes. Overall, 86/266 (32.3%) goats suffered from mastitis, whose 32.5% (28/86) infected with Staphylococci. Most of strains were susceptible to many antibiotics, except for penicillin, tetracycline and fusidic acid, and the resistance incidence of which were 21.4%, 25%, and 10.7% respectively. Only twelve (42.8%) isolates were resistant to utmost two antibiotics and bi-drug resistance was associated to four Coagulase negative Staphylococci (CNS) strains. Nine different species were identified in CNS isolates while S. aureus strains were clustered within CC130-agr3-[lukF-P83, lukM+] (four isolates; 50%), CC6-agr1 (three isolates; 37.5%) and one agr4 non-typables cluster. Enterotoxins genes were found in 62.5% of the S. aureus strains. Of which sec, sel were the most prevalent (62.5%: n = 5) followed by sea (12.5%: n = 1). CC130 showed edinB, tst and tetK (2/4) genes and CC6 were positive to cna and fosB genes. The current investigation provide the data for prevalence of Staphylococci in goats in Tizi-Ouzou region and S. aureus characterization which will help in tracking evolution of epidemic strains and their control methods.