A Cross-Sectional Study of Bovine Mastitis in and Around Bahir Dar and Antibiotic Resistance Patterns of Major Pathogens
No Thumbnail Available
Date
2004-06
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa Universty
Abstract
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 evalua te somatic cell
countin identifying
intramammary infections. Clinical prevalence was detemined
through examination of
abnomlalities of milk, udder or cow. California mastitis test (CMT)
and culture were used for
subclinical mastitis determination. Agar dise diffusion was used
for antibiotic susceptibility
test. Somatic cell count was conducted following standard
procedures described in
International Dairy Federdtion for enumeration of cells with direct Mi
croscopic 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% )
incrossbreds 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. Amon
g
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 negalive
staphylococci (CNS),
S.
aureus. Str. agalaciae. Sir dysgalactiae. Str. uberis. Micrococcus
species, C. bovls. A. pyogens B. cereus, and S. intermedius. Amon
g
these, the most frequent
isolates were CNS (49 .6% of the total isolates). S. aureuS (17.9% ),
Str. agalacliae (8.2%) and
Str dysgalacliae (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 isolate
s
were most sensitive to
sulfisoxazole. Staphylococcus; aureus was susceptible to all drugs
except streptomycin.
Staphylococcus aureus was 91.7% susceptible to oxacillin, howev
er, CNS were less
susceptible (68.2%) in vilro.
To evaluate somatic cell count (SCC) in identifying imramamary infect
ion fo r crossbreds. 10
cutoff poims between 100000 cells /ml and 300000 cell/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 loca l zebu breeds
. The sensitivity for
crossbreds range from 79.16 % (al 300000 cell/ml cutoff point)
to
95.80 % (al 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 usc SCC as a
diagnostic tool on a national seale further study need to be conducted with improved cultural
technique and automatic cell counters. Cross breed cows had high
SCC
compared to local
zebu cow. The SCC was
significantly (p<O.05) affected by infection status. breed and late
lactation stage.
Description
Keywords
clinical /subclinical mastitis/ prevalence /susceptibility /Somaric Cell Count /threshold /crossbred /zebu