Manickam, R.Ponnusamy, P.TANUVAS2017-09-012017-09-012017http://krishikosh.egranth.ac.in/handle/1/5810030166This study was performed to identify various bacteria from feces of calves suffering from diarrhea, and to determine in vitro antimicrobial activity. Fecal samples were collected from 80 diarrheic calves and primarily tested for the presence of Escherichia coli, Salmonella spp. and Staphylococcus aureus using bacteriological examination, biochemical reactions. 60 bacterial isolates from the 80 fecal samples were identified using bacteriological and biochemical methods. Escherichia coli was considered to be the most frequent bacterium isolated numbering 22 (36.66%) followed by Salmonella sp. as the second most prevalent 11 (18.33%). Further isolates such as Staphylococcus aureus 8 (13.33%), Enterococcus faecalis 5 (8.33%) and Shigella sp. 3 (5.00%) were isolated and identified. Among the antibiotic sensitivity 55.0% were sensitive to Amikacin, 55% were sensitive to Ceftriaxone, 69.0% sensitive to Ciprofloxacin, 81.5% were sensitive to Kanamycin, and 75.5% were sensitive to Nalidixic acid (Table 4). Similarly majority of the bacterial isolates showed resistance to Ampicillin (75.0%), Amoxycillin (62.0%), Ceftriaxone (45.0%), Chloramphenicol (68.0%), Gentamicin (50.0%), Streptomycin (65.0%) and Tetracycline (74.0%).en-USVeterinary ScienceArticle