Across- Sectional Study of Bovine Mastitis in and around Bahirdar and Antibiotic Resistance Patterns of Major Pathogens
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Date
2004-06
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Addis Ababa University Faculty Of Veterinary Medicine
Abstract
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
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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.
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Keywords
clinical subclinical masti tis! prevalence bacterial isolate antibiotic susceptibility Somaric Cell Count threshold crossbred zebu