Across- Sectional Study of Bovine Mastitis in and around Bahirdar and Antibiotic Resistance Patterns of Major Pathogens

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Addis Ababa University Faculty Of Veterinary Medicine


Three hun dred fi ft y o ne (J 95 loca l zebu and 156 Ho lste in x Loca l Zebu) la ctating cows o f sma ll holde r p ri va te fa rm s in Ba hir Dar milk shed were examined fro m Septe mber, 2003 to Ma rch, 2004 ( 0 de te rm ine mastiti s prevale nce, isolate pa thogens in vo lved, eva lua te the ant ibiotic susceptib ili ty pro fi les a nd [ 0 eval ua te soma ti c cell count in identify in g intrama mmary in fec ti o ns. Clinical preva lence was deteml in ed th rough examinati o n of abno mla lities of m ilk , udde r or cow. Cal ifornia mastitis tes t (C MT) and c ulture were used for subclinical mastiti s de te rm ination. Aga r disc di ffusion was used fo r antibiotic suscept ibi lity test. Somati c cell count was condu cted foll owing standard procedures desc ri bed In Inte rn ati o nal Dairy Federdt io n for e num eratio n of ce ll s wi th direc t Mi croscopic me thod. Clinical prevalence at cow level was 3.9% in crossbreds and no nc in local zebu breeds. Subclinical mastit is a t cow level based o n C MT was high (34.4%) in crossbreds compared to indigenous zebu (17.9%) (p < 0.05). Quarter subclinical prevale nce based on eMT was 17 .90% and 4.95% for c rossbreds and local zebu. respectively. Amo ng potential risk fac tors considered, stage of lactation, parity and breed were found 10 afTecI the occurrence of mastitis significantly (p < 0.05). The pathogens isola ted from ma stitic milk were coagulase negalive staphylococci (eNS), s. aureus. Srr. agalacliae. Sir dysgalactiae. Sr r. uberis. Micrococcus species, C. bovls. A. pyogefls, B. cereus, and S. illtermedius. Among these, the most frequent isolates we re eNS (49 .6% of the 10la l isolates). S. alirellS (17.9%), Srr. agalacliae (8.2%) and SIr dysgalacliae (6:7%). Seven antibiotics including sul fi soxazole. tetracycline, erythromycin. oxacil lin, chloramphenicol, cJindamycin, and streptomycin were tested o n 81 isola tes. Except fo r streptomycin, all isolates \\ere sensitive to all antibiotics. All isolates were most se nsi tive 10 sulfisoxazo le. Staphylococcw; allreus was susceptible to all drugs except streptomycin. SllIphylococcus Ollreus was 91.7% susceptib le to oxacillin, however, CNS were less susceptible (68.2%) ill vilro. To evaluate somatic cell count (SeC) in ide nt ify ing imramamary infect ion fo r crossbreds. 10 cutoff poims between 100000 cellsl ml and 300000 celJSJml were evaluated for the ir sensllivity and speci-ficity in comparison with cu ltural results. Sim ilarly, cutoff points between 80000 cell ml and "250000 cell ml were take n fo r loca l zebu breeds. The sensitivity for VI\ crossbreds range from 79.16 % (al 300000 ce ll slml cutoff point) 10 95.80 % (al 100000 cells! ml) and similarly specificity from 80.28% to 45.52%. Fo r 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 anempl in Ethiopia and to usc SCC as a diagnostic tool on a national sqle further study need to be conducted with improved cultural technique and automatic cell counters. Cross breed cows had high see compa red to local zebu cows. The sec was significantly (p<O.05) affected by infection status. breed and late lactation stage.



clinical subclinical masti tis! prevalence bacterial isolate antibiotic susceptibility Somaric Cell Count threshold crossbred zebu