In the present study, a total of 150 mastitis milk samples were collected from sheep and
goat (75 for each one) and were analyzed for the presence of S.aureus.. The obtained
results indicate that this bacterium observed in 20% of these samples (21.33% from sheep
and 18.66% from goat) .The study of antibiotic susceptibility test to 9 different antibiotics
showed that S. aureus was 100% resistant to penicillin and 100% sensitive to
vancomycin, gentamycin , clarithromycin and chloramphenicol . whereas for cefoxitin
(alternative to methicillin) resistance was 47%.There were a variable sensitivity
percentage for the rest of antibiotics: Tetracycline (70%), Ciprofloxacin (80%) ,
Clindamycin (83%). The biofilm-forming ability of S. aureus was evaluated via
microtiter plates and the result revealed that, all the studied isolates were either moderate
biofilm producer or weak biofilm producer while the non-biofilm producer and strong
biofilm producer were not detected among the tested isolate.The relationship between
biofilm formation and resistance to methicillin showed there as no significant differences
(P>0.05) in the percentage of weak and moderate biofilm producers between MRSA and
MSSA isolates. PCR analysis was applied to DNA extracted from S.aureus isolates from
milk samples .The results of PCR assay revealed that all S.aureus isolates gave positive
results for both icaA and icaD genes (100%) with Product size 151 and 211 bp,
respectively.
Results of this study indicate that biofilm producing S.aureus have a major role player on
the occurrence of mastitis .In addition, there was high prevalence of MRSA isolates
(47%) in mastitic milk at the study area