Phenotypic, Antimicrobial and Genetic Diversity of Staphylococcus aureus from Camel (Camelus dromedarius) Skin Lesions

Abstract

Skin wounds and abscesses are important health and welfare concerns in dromedary camels, and Staphylococcus aureus is frequently associated with suppurative lesions. This study characterised camel-derived S. aureus using phenotypic testing, antimicrobial susceptibility profiling and random amplified polymorphic DNA (RAPD) fingerprinting to assess strain diversity. Seventy samples from naturally occurring lesions and selected normal skin-associated sites were examined bacteriologically, of which 46 (65.7%) were positive for S. aureus. Isolates were evaluated for free coagulase, haemolysis, haemolysin production, biochemical variation and susceptibility to 33 antimicrobial agents. Thirty representative isolates were examined for haemolysin production, and 21 isolates were selected for RAPD analysis using ten arbitrary primers. Coagulase-positive isolates predominated, haemolytic and haemolysin profiles varied, and biochemical testing identified 18 biotypes. Antimicrobial responses were heterogeneous, with several fluoroquinolones and aminoglycosides showing comparatively high in vitro activity in the historical dataset, whereas several older agents showed poor activity. RAPD analysis generated 118 scorable bands, of which 117 (99.2%) were polymorphic, and separated the typed isolates into two broad genetic groups. These findings indicate substantial phenotypic and genetic heterogeneity among camel-associated S. aureus. Culture-based susceptibility testing and molecular typing provide complementary epidemiological information; however, the historical antimicrobial data should not be interpreted as current treatment guidance, and contemporary surveillance should use current susceptibility standards and higher-resolution genomic methods where available.