Tropical Veterinary Medicine

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Browsing Tropical Veterinary Medicine by Subject "bacterial isolate"

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    A cross-Sectional Study of Bovine Mastitis In and Around Bahir Dar and Antibiotic Resistance Patterns of Major Pathogens
    (Addis Ababauniversity, 2004-06) Almaw, Gizat; Gebreab, Feseha (Prof)
    Three hundred fifty one (195 local zebu and 156 Holstein x Local Zebu) lactating cows of smallholder private farms in Bahir Dar milk shed were examined from September, 2003 to March, 2004 to determine mastitis prevalence, isolate pathogens involved, evaluate the antibiotic susceptibility profiles and to evaluate somatic cell count in identifying intramammary infections. Clinical prevalence was determined through examination of abnormalities of milk, udder or cow. California mastitis test (CMT) and culture were used for subclinical mastitis determination. Agar disc diffusion was used for antibiotic susceptibility test. Somatic cell count was conducted following standard procedures described in International Dairy Federation for enumeration of cells with direct Microscopic method. Clinical prevalence at cow level was 3.9% in crossbreds and none in local zebu breeds. Subclinical mastitis at cow level based on CMT was high (34.4%) in crossbreds compared to indigenous zebu (17.9%) (p < 0.05). Quarter subclinical prevalence based on CMT was 17.90% and 4.95% for crossbreds and local zebu, respectively. Among potential risk factors considered, stage of lactation, parity and breed were found to affect the occurrence of mastitis significantly (p < 0.05). The pathogens isolated from mastitic milk were coagulase negative staphylococci (CNS), S. aureus, Str. agalactiae, Str. dysgalactiae, Str. uberis, Micrococcus species, C. bovis, A. pyogens, B. cereus, and S. intermedius. Among these, the most frequent isolates were CNS (49.6% of the total isolates), S. aureus (17.9%), Str. agalactiae (8.2%) and Str. dysgalactiae (6.7%). Seven antibiotics including sulfisoxazole, tetracycline, erythromycin, oxacillin, chloramphenicol, clindamycin, and streptomycin were tested on 81 isolates. Except for streptomycin, all isolates were sensitive to all antibiotics. All isolates were most sensitive to sulfisoxazole. Staphylococcus aureus was susceptible to all drugs except streptomycin. Staphylococcus aureus was 91.7% susceptible to oxacillin, however, CNS were less susceptible (68.2%) in vitro. To evaluate somatic cell count (SCC) in identifying intramamary infection for crossbreds, 10 cutoff points between 100000 cells/ ml and 300000 cells/ml were evaluated for their sensitivity and specificity in comparison with cultural results. Similarly, cutoff points between 80000 cell/ml and 250000 cell/ml were taken for local zebu breeds. The sensitivity for viii crossbreds range from 79.16 % (at 300000 cells/ml cutoff point) to 95.80 % (at 100000 cells/ ml) and similarly specificity from 80.28% to 45.52%. For local zebu breeds in the same order, sensitivity range from 58.82% to 88.23% and specificity from 45.82% to 85.15%. To establish threshold level this study was a first attempt in Ethiopia and to use SCC as a diagnostic tool on a national scale further study need to be conducted with improved cultural technique and automatic cell counters. Cross breed cows had high SCC compared to local zebu cows. The SCC was significantly (p<0.05) affected by infection status, breed and late lactation stage. Keywords: clinical / subclinical mastitis/ prevalence/ bacterial isolate/ antibiotic susceptibility / Somatic Cell Count / threshold / crossbred / zebu
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    Prevalence of bovine mastitis in lactating cows among small holder dairy herds and antimicrobial sensitivity test on major isolated pathogens in and around Gondar
    (2007-06) NIBRET, MOGES; Dr.Yilkal Asfaw, Dr. Kelay Belihu
    A cross _ sectional study was conducted on 322 local and crossbred lactating hand milked small holder cows in and around Gondar from September 2006 to March 2007 to determine prevalence, the causal agents of infection, associated risk factors and tests susceptibility to drugs using California Mastitis Test, clinical inspection of udder, and bacterial culture. Of the total cows examined, 32.6% (322) had mastitis, 0.93 % (3) was clinical and 31.67% (102) sub clinical mastitis. Out of 1249 quarters examined 164 (13.13%) were found to be infected, 7(4.27%) clinically and 157 (95.73%) sub clinically from 1288 quarters examined 39 (3.02%) were blind. Clinical prevalence at cow level was 0.93% in crossbreds and none in local zebu breeds. Sub clinical mastitis at cow level based on CMT was 28.57% in crossbreds compared to indigenous zebu 3.10% (P<0.05). Quarter sub clinical prevalence based on CMT was 16.05% and 5.12% for crossbreds and local zebu, respectively. Among potential risk factors considered breed, age, parity and stage of lactation were found to affect the occurrence of mastitis significantly (p< 0.05). The prevalence of mastitis was significantly higher in Holstein _Friesian crossbreds than indigenous zebu, in the early lactation stage than in the mid lactation stage. Of 176 CMT and clinically positive udder quarter samples analyzed microbiologically 164 were culturally positive for known mastitis pathogens and 1085 were negative. Of the 164 positive samples isolation rate of Staphylococcus aureus 16.5%, Coagulase negative Staphylococci 31.1%, Streptococcus agalactiae 15.9%, Streptococcus dysgalactiae 14.0%, Streptococcus uberis 6.7%, Micrococcus spp 7.3%, Corynebacterium bovis 2.4%, Actinomyces pyogens 1.2%, Bacillus cereus 0.6% and Escherichia coli 4.3%. Staphylococcus aureus, Coagulase negative Staphylococcus, Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis, Micrococcus species, Corynebacterium bovis, Actinomyces pyogenes, Bacillus cereus and Escherichia coli were isolated from cases of sub clinical mastitis. Generally, it was found that Sulfisoxazole was the most effective antibiotic VII where 91.07% of the total isolates were found susceptible, followed by clindamycin and kanamycin (89.3%), (88.4%) The least effective antibiotics were streptomycin (45.5%) and ampicillin (49.1%). Tetracycline, erythromycin, chloramphenicol, oxacillin, 65.2%, 59.8%, 64.3%, 58.04% respectively, were categorized as drugs of weak efficacy. Inadequate sanitation of dairy environment, poor animal health services and lack of proper attention to health of the mammary glands were important factors contributing to high prevalence of mastitis. Some recommendations were forwarded to reduce the tend of mastitis in the study area.