drug. The aim of this study to identify the most common causes of bacterial mastitis in cows in Omdurman locality
and to measure the effectiveness of Tylosin and Enrofloxacin in the treatment of bacterial mastitis in vitro.
MATERIALS AND METHODS
Study area is Omdurman city which located at the intersection of latitude 15 degrees 41 minutes north,
longitude 32 degrees 37 minutes east, on the west bank of the Nile opposite the coupler with a tributary of the
White Nile, and off both Khartoum and Khartoum North, which are linked by the bridge of the White Nile and
Shambat bridge. The numbers of dairy cows were more in this locality than the other sites of Khartoum province.
A total of 30 suspected cows were examined clinically: took the body temperature, pulse, heart rate,
respiration, auscultation and palpation the last examination especially for mammary gland and supra mammary
lymph nodes for presence of mastitis. Sixty milk samples from mastitic cows were collected. Mastitis was
diagnosed when there were visible or palpable singes of udder, inflammatory changes in milk secretion, or through
bacteriological examination of milk. During the study 60 milk sample were encountered from 30 cows suffering
from clinical and subclinical mastitis. Milk sample were taken under from infected quarters only under aseptic
condition for bacteriological studies. The fore milk was stripped off and about 5 ml of milk were drawn in sterile
disposable bottle. All samples collected were immediately placed on ice in a thermo flask after collection.
Isolation and identification of bacteria
Culture. Milk samples were collected from mastitic cows were cultured in two media: Blood agar and
MacConkeys agar. After culturing the plates were incubated for 24 hours at 37ºC. Purification was achieved by
further subculturing on nutrient agar and incubated at 37ºC for 24 hours. After purification, a full loop from purified
culture was taken and a smear was made and stained with Gram´s stain to differentiate between Grams positive
and Grams negative bacteria and to see the shape of bacteria. Plates were examined for cultural characteristics
particular for haemolysis and coagulase production using human plasma. A positive coagulase test was judged as
Purification of cultures. Purification of culture was made by sub-culturing a part of a typical and well isolated
colony on nutrient agar. This process was repeated twice. The resulting of growth was checked for purity by
examining smears stained with Gram´s stain method.
Identification of bacteria. The purified isolated bacteria were identified according to criteria outlined by Barrow
and Feltham (2003) which included of: Reaction of Grams stain, shape of the bacterial colonies, presence or
absence of spores, motility, the colonial characteristics on different media, haemolysis of blood agar and
biochemical tests. All biochemical tests for identification of isolated bacteria were performed according to Barrow
Antibiotic sensitivity test. Some of the bacteria that isolated through microbiological procedures were
subjected to antimicrobial susceptibility test by disc diffusion method to identify the effectiveness of the Tylosin and
Enrofloxacin. The sensitivity against Tylosin and Enrofloxacin were determined on Mueller Hinton agar as described
by National Committee for Clinical Laboratory Standards (NCCLS, 2002). The results were obtained by measuring
the diameter of the growth inhibition zone around the antibiotic disc for each isolated bacterial strain and recorded
as sensitive, intermediate and resistant.
Identification of isolates
Out of the 100 isolates 70 (70%) were gram positive, and 30 (30%) were gram negative bacteria. Among the
total of the gram positive isolates, 40 (57.1%) were Staphylococcu spp., Bacillus spp. were 18 (25.7%),
Streptococcus spp. were 6 (8.6%), Corynebacterium spp. were 4 (5.7%), Actinomyces spp. were 2 (2.9%) and from
gram negative isolates, Enterobacter spp. were 26 (86.7%) and E. coli were 4 (13.3%) (Figure, 1). The isolated
Staphylococcus spp. in this study was divided into two groups: Coagulase – positive included Staph. aureus and
Staph. hyicus. Coagulase – negative were Staph. epidermidis, Staph. chromogens, Staph. simulans and Staph.
Citation: Almobarak ME, Mohammed Salih RR and Gibreel HH (2020). In vitro efficacy of Tylosin and Enrofloxacin in treatment of bovine mastitis causing bacteria in