Prevalence of Subclinical Mastitis in Small Ruminants and Role of Staphylococcus Species in Such Infection

Abstract

The current study was carried out on a number of sheep and goats farms during the period extended from January 2016 till the end of December 2017 in order to estimate the prevalence of subclinical mastitis in small ruminants and highlight the role of Staphylococcus species in inducing such infection. For this aim, about 940 milk samples collected from sheep and goats farms (455 samples/ sheep and 485 samples/ goats) were subjected to California Mastitis test (CMT) to detect the prevalence of subclinical mastitis, then positive CMT samples in addition to; 100 bedding samples (50 samples / each species) collected from different sites of animal s yards particularly from wetted areas with high moisture and organic matter load and 100 water samples collected from different sites of animal s yards (50 samples / each species) were subjected to the ordinary bacterial culturing steps for isolation and identification of Staphylococcus species. The results revealed prevalence of subclinical mastitis estimated by 32.96% and 30.92% in sheep and Goat farms, respectively. The total prevalence of Staphylococci in Sheep farms was 27.2% where S. aureus accounted for 12.4% and Coagulase Negative Staphylococci (CNS) represented the highest percentage (14.8%). The highest isolation rate recorded in bedding samples (34.0%) followed by milk samples (26.0%) and water samples (24.0%), while in goats farms the prevalence of Staphylococci species was 32.0% (16.8% S. aureus and 15.2% CNS) with highest rate of isolation from bedding samples (36.0%) followed by milk samples (34.0%) then water samples (22.0%). In addition, the isolated Staphylococcus strains where tested for their sensitivity to certain commercial antibiotics using disc diffusion method. The results revealed complete resistant of isolated S. aureus to Enrofloxacin (5 µg) and Oxytetracycline (30 µg) and moderate sensitivity to Amoxicillin (10 µg) and Erythromycin (15 µg). While CNS showed complete resistant to Flumequine (30 µg), Doxycycline (30 µg) and Sulpha.-Trimethoprim (25 µg), in contrary, they were highly sensitive to Amoxicillin (10 µg) and Erythromycin (15 µg) antibiotics. At last, molecular detection of clfA gene specific for coagulase positive Staphylococci were performed.