Diarrhoea, E. coli, Salmonella, Staphylococcus, Goat
Government Goat Development farm, Sylhet, District Veterinary Hospital, Mirjajangal, Sylhet, Upzilla Livestock Department, Jaintapur, Sylhet
The study sample was the faeces collected from rectum of diarrhoeic goats. Both male and female goats were considered. About 100 faecal samples from diarrhoeic goats were collected from the five selected areas in and around Sylhet region. The samples were collected in four steps; in each step, 5 samples were collected and finally 20 samples were collected from Government Goat Development farm, Sylhet, District Veterinary Hospital, Mirjajangal, Sylhet, Upzilla Livestock Department, Jaintapur, Sylhet ,Kazir bazar, and Shah poran region, Sylhet respectively. The faecal samples were collected from diarrhoeic goats directly from rectum by spatula and stored in polythene bags. Each sample was collected separately and was taken in icebox. Then the samples were transported from the Farms to the laboratory, after that each sample was mixed aseptically with sterile distilled water at a ratio of 1:10. Then the sample was shaken properly to make a homogenous suspension. Later on 10 fold serial dilutions (1:10) were prepared ranging from 10-2-10-9 according to the recommendation of International Organization for Standardization [7]. Then the diluted samples were taken in nutrient broth and mixed well. Later on the nutrient broth containing samples were placed into incubator to incubate the samples for 24 hours.
Isolation and identification of bacteria- The bacteriological analysis of different samples was done according to the standard method[8].The criteria employed for the isolation and identification of bacteria from the mentioned samples were based on the morphological, cultural and biochemical characterization[9], [10]. Morphological( size, shape, arrangement, motility) study were done by Gram?s staining and Hanging drop slide, Colony characteristics were observed on different media, Hemolytic activity was seen on blood agar, Biochemical reactions were performed by Catalase test, and Indole test, Methyl red (MR) test, Voges Proskauer (VP) test, and Triple sugar Iron (TSI) agar test. Then antibiotic sensitivity test was also done by disc diffusion method. Firstly TVC (Total Viable Count) & TCC (Total Coliform Count) were determined by using plate count agar and Violet red bile agar. The suspected colony from these media was subcultured in Nutrient agar, Eosin methylene blue (EMB) agar, MacConkey agar, Salmonella-Shigella (SS) agar, Blood agar, Violet red bile (VRB) agar and Brilliant green agar (BGA) to promote the growth of a particular type of bacterium. Finally the pure culture was obtained from the selective media. Then staining these bacteria with “Gram?s staining” method along with motility tests. After that from the pure culture the biochemical tests were carried out. Strict aseptic measures were maintained during the period of study. After performing the above mentioned tests, the results were analyzed and the isolated bacteria present in samples were identified. Cultural characterization of bacterial isolates At first samples were incubated in nutrient broth with the help of sterile inoculating loop and incubated at 37º C for 24 hours. From the nutrient broth cultured samples were inoculated onto nutrient agar, MacConkey agar, SS agar and EMB agar with the help of sterile inoculating loop and incubated at 37º C for 24 hours. The incubated media were then examined for growth of bacteria. Biochemical characterization of bacterial isolates- Isolated organisms with supporting growth characteristics on various media were maintained in nutrient broth and were subjected to the following biochemical tests named Catalase test, Sugar fermentation test, Indole test, MR test and VP test. Catalase test- This test is used to differentiate the bacteria that produce the enzyme catalase such as Staphylococcus, from non-catalase producing bacteria such as Streptococci. The test was performed by transferring a small amount of growth, preferably a single colony, from solid medium to a microscope slide. A drop of fresh hydrogen peroxide (3%) added, and then a cover slip is applied. The production of gas bubbles constitutes a positive reaction.