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Abstract
Mastitis is still implicated as one of the major disease problems in dairy animals. from the economical point of view, mastitis results in marked reduction in amount of milk yield or even complete destruction of mammary gland and significant alteration in composition of milk. Also mastitis is sometimes associated with many zonootic diseases in which milk acts as a vehicle of infection.
California Mastitis Test was applied to determine the prevalence rate of subclinical mastitis. Examination of 55 apparently healthy cows and 71 apparently healthy buffaloes by CMT revealed that, subclinical mastitis was found in 34 of cows and 59 of buffaloes with an incidence of 61.8% and 83.1% respectively.
A total number of 388 individual quarter milk samples were collected from 97 clinically mastitic cows and 136 quarter milk samples collected from 34 subclinically mastitic cows the results revealed that, clinical mastitis constituted 232 quarter milk samples with an incidence of 44.3% and subclinical mastitis was detected in 76 quarter milk samples with an incidence of 14.5%.
Clinical mastitis was detected in 141 quarter milk samples, out of 192 quarter milk samples collected from 48 clinically mastitic buffaloes with an incidence of 32.9%. Meanwhile subclinical mastitis was detected in 138 quarter milk samples, out of 236 quarter milk samples collected from 59 subclinically mastitic buffaloes with an incidence of 32.2%
The affection in two quarters was higher than the other quarter’s affection in clinically and subclinically mastitic cows with an incidence of 34.0% and 38.2% respectively. In clinically mastitic cows three quarters affection are 27.8% followed by one quarter affection was 21.6% then four quarters affection were 16.5%. Meanwhile in subclinically mastitic cows one quarter affection was 26.5% followed by three quarters affection were 20.6% then four quarters affection were 14.7%.
It is clear that affection in three quarters in clinically mastitic buffaloes were 37.5% followed by four quarters affection were 33.3% then in two quarters were 18.8% and in one quarter was 10.4%. On other hand affection two quarters in subclinically mastitic buffaloes were 37.3% followed by three quarters affection were 25.4% then one quarter affection was 22.0% and four quarters affection were 15.3%.
The isolates of staphylococci were Gram positive cocci, catalase positive and growth occurred on Baird Parker medium, nutrient agar, blood agar and mannitol salt agar. All isolates fermented glucose anerobically.
All S. aureus isolates were Gram positive cocci arranged in clusters, they were catalase and coagulase producer. Particularly anaerobic utilization of mannitol distinguished S. aureus from S. intermedius or S. hyicus.
Staphylococcus species were isolated from 93 samples with the percentage of 30.2 out of 308 examined milk samples in mastitic cows. In clinical mastitis the incidence of S. aureus isolates were 17.7% as major pathogen followed by S. epidermidis (6.9%), S. intermedius(4.3%) and the lowest incidence was S. hyicus as 1.7% . While in subclinical mastitis the incidence of S. aureus were 15.8%, S. epidermidis was 9.2% , S. intermedius was 2.6% and S. hyicus was 1.3% .
The distribution of staphylococcus species among the examined quarters in mastitic buffaloes were 30.8%. It is clear that, the majority of isolates recovered from clinical and subclinical cases (25.5% and 10.9%) were S. aureus followed by S. epidermidis (6.4 % and 7.9%), S. intermedius (3.5% and 3.6%) and S. hyicus ( 1.4% and 2.2%) respectively.
Seventy out of 104 S. aureus examined had lipase activity (67.3%) and the highest lipase activity was recorded among S. aureus isolated from subclinically mastitic buffaloes (73.3%), followed by clinically mastitic cows (70.7%) then clinically mastitic buffaloes (63.9%)and subclinically mastitic cows (58.3%).
Fibrinolysin activity of S. aureus isolated from clinically and subclinically mastitic cows were 80.5% and 75.0% respectively. Meanwhile Fibrinolysin activity of S. aureus isolated from clinically and subclinically mastitic buffaloes were 69.4% and 66.7% respectively.
Eighty nine out of 104 S. aureus isolates had DNase activity (85.6%). All isolates of clinically mastitic cows had DNase activity (100%) and lower percentage was recorded among isolates detected from subclinical mastitic buffaloes (60.0%). Meanwhile DNase activity was 86.1% and 66.7% among S. aureus isolated from clinically mastitic buffaloes and subclinically mastitic cows respectively.
Out of 104 S. aureus isolates, 88 (84.6%) showed SpA by agglutination test positive. A higher percentage was recorded among S. aureus isolates from clinically mastitic cows (90.2%) and lowest percentage was 80.0% among S. aureus isolates from subclinical mastitic buffaloes. Meanwhile 83.3% and 80.6% of S. aureus isolates from subclinically mastitic cows and clinically mastitic buffaloes were SpA positive respectively.
The majority of S. aureus isolates recovered from mastitic cows were susceptible to methicillin (96.2%), gentamycin (90.6%), amoxicillin + clavulinic acid, enrofloxacin (84.9% each), ciprofloxacin (83.0%) and rifampicin (79.2%). Meanwhile high resistance was recorded to streptomycin (71.7%), penicillin (64.2%), oxytetracycline (54.7%) and sulphamethoxazole-trimethoprim(39.6%) .
In mastitic buffaloes, high resistance was recorded to penicillin (78.4%) among the examined S. aureus isolates followed by streptomycin (68.6%), oxytetracycline (64.7%) and sulphamethoxazole-trimethoprim (58.9%). Meanwhile the majority of S. aureus isolates were susceptible to methicillin (98.0%), enrofloxacin (86.3%), amoxicillin + clavulinic acid (84.3%), rifampicin (82.4%), neomycin (78.4%), gentamycin (76.5%), ciprofloxacin (74.5%) and clindamycin (66.7%).
RPLA test was used in this study as a recent technique for detection of staphylococcal enterotoxins. The obtained results showed high incidence of type C enterotoxin followed by type A then type B and type D with an incidence of 38 (36.5%), 15( 14.4%) 11(10.6%) and 3 (2.9%) respectively.
A total number of 12 isolates previously tested by using RPLA and the results of RPLA were confirmed by using multiplex PCR as recent technique confirmatory test. Results obtained showed that 100% agreement between RPLA and multiplex PCR in the presence of A, B, C and D enterotoxins. Seven isolates produced enterotoxin C, four isolates produced enterotoxin E, one isolate for each A, B and D respectively and four isolates produced no enterotoxins.
Five S. aureus isolates were tested with MR1-MR2 primers which amplify the 1339 bp fragment of mecA gene. Results revealed positive amplification of the 1339 bp fragment of mecA gene from the extracted DNA of three of S. aureus isolates out of five examined isolates.