The research work was conducted at the Department of Microbiology and Hygiene, Bangladesh Agricultural University (BAU), Mymensingh. The samples were collected from Reptiles Farm Ltd. (RFL); Valuka, Mymensingh, Bangladesh. To collect the oral swabs, a piece of wood was used to keep the mouth of the crocodile open. A tight rubber band was used to avoid biting. Then sterile cotton buds were introduced inside its mouth cavity and the swab was collected. For nasal swabs, sterile cotton buds were introduced into the nasal cavity of the crocodile. The cloacal swab was also collected by using sterile cotton buds. Aseptic measures were undertaken during the collection of samples. After collection, the swabs were transferred into cryovials containing 0.1% peptone water. Immediately after transferring in cryovials, all samples were brought to the Bacteriology Laboratory of the Department of Microbiology and Hygiene, Bangladesh Agricultural University (BAU), Mymensingh, through cool chain maintaining. Samples were inoculated into the Nutrient broth and incubated for 24 hours at 37°C for better nourishment of the desirable organisms. Isolation of bacteria is carried out based on the cultural characteristics of different selective media. For this one loopful of an enrichment culture of oral, nasal, and cloacal swabs was separately streaked in duplicate onto Mannitol salt agar (MSA, Hi-media, India), Thiosulfate Citrate Bile Salts Sucrose agar (TCBS, Hi-media, India), Salmonella-Shigella (SS) agar (Hi-media, India), Eosin Methyline Blue agar (EMB, Hi-media, India), Blood agar( BA, Hi-media, India) respectively and incubated for 24 hours at 37 ºC. Single colony grown onto selective media were further sub-cultured onto the particular media until pure bacterial cultures were obtained. To identify the bacteria Gram's staining method (Ashikuzzaman et al., 2015), motility test (Lijon et al., 2015), sugar fermentation test (Hemraj et al., 2013), and biochemical tests such as Catalase (Hemraj et al., 2013), Indole (Hemraj et al., 2013), MR-VP (Hemraj et al., 2013) and coagulase tests (Islam et al., 2016) were performed. Polymerase chain reaction (PCR) method was used to identify E. coli by amplifying 585bp, 606 bp, 374 bp, 889 bp, and 497 bp fragments of 16srRNAgene , stx1 and stx2 gene, hly gene, and rfb0157 gene, respectively (Schippa et al., 2010; Heuvelink et al., 1995; Wieler et al., 1996; Paton and Paton, 1998). For detection of Salmonella spp. 469 bp and 274 bp fragments of 16srRNA gene and typh gene were amplified respectively by following PCR method (Cohen et al., 1993). Polymerase chain reaction (PCR) assay was also performed to identify Staphylococcus spp. by amplifying 241 bp and 279 bp fragments of 16s rRNA gene and nuc gene, respectively (Stuhlmeier and Stuhlmeier, 2003; Kalorey et al., 2007). Antibiotic sensitivity test of isolated E. coli (n=30), Salmonella spp. (n=30), Bacillus spp. (n=10), Staphylococcus spp. (n=10) and 10 Vibrio spp. (n=10) were performed against eight commercially available antibiotic discs such as Ampicillin, Azithromycin, Cephalexin, Ciprofloxacin, Chloramphenicol, Gentamicin, Penicillin and Vancomycin (Hi-media, India). The disc diffusion method was used to detect antibiotic susceptibility of the isolated bacteria according to the guidelines of Cockerill and Clinical and Laboratory Standard Institute (CLSI), 2012.