Shrimp samples were collected from three different departmental chain shops and three local retail markets at Dhaka city in between April, 2010 and December, 2010. A total of 24 samples where 4 ? 5 shrimps were taken in each sample, 12 from departmental chain shops and 12 from local markets were collected to assess the bacterial load. Identification was made according to Shafi(7). The shrimp samples were collected in special sterile Ziploc bags to avoid further contamination and transported in an insulated box with ice to maintain the temperature (4 ? 6ºC) and stored at – 20ºC at the laboratory until use(8). Samples were processed and used within 24 hrs of collection. The samples were thawed at room temperature for 5 ? 6 hrs to melt the ice and were taken to the safety cabinet to peel off the shell remaining the head. The edible part body was taken and made small pieces using sterile scissors. Shrimp (25 g) sample was weighed carefully and accurately by using a weighing scale and dissolved in 225 ml of 0.85% NaCl solution in a stomacher bag. Each sample was then stomached for 60 sec separately. Stomacher treated samples (0.1 ml) was then poured or spread plated in the microbiological medium. The microbiological analysis was performed as per the standard methods adopted from Online Bacteriological Analytical Manual, USFDA for detection, enumeration and identification of individual organisms. Total bacterial count (TBC) was obtained directly on nutrient agar (Becton Dickinson, France). The colonies were incubated at 35 ? 37ºC for 24 hrs and expressed in cfu/g. Nutrient agar was used without saline water because it allows only salt tolerant bacteria to grow. Dilutions made for TBC were pour?plated on MacConkey agar (Oxoid Ltd., Hampshire, England); typical pink colonies were counted after 24 h of incubation at 35 ? 37ºC. The suspected isolates were streaked on mFC agar plates and incubated at 44.5ºC for 24 hrs. Typical blue colonies were counted and was further confirmed by growing in eosin methylene blue (EMB) agar plates (Oxoid Ltd., Hampshire, England). The sample (25 g) was homogenized in saline water. After the samples were enriched a loopful of growth from the broth was streaked on Salmonella?Shigella agar (SSA; Oxoid), typical black colonies from plates were isolated and identified by biochemical tests. Xylose lysine deoxycholate (XLD) agar was also used for the selective isolation of Shigella and Salmonella spp. After appropriate serial dilutions, the samples were pourplated on XLD agar (Oxoid Ltd., Hampshire, England). Typical pink and translucent colonies with or without rough edges were picked up after 48 hrs of incubation at 35 ? 37ºC and confirmed by biochemical tests. The sample (25 g) was homogenized in 225 ml of alkaline peptone water (APW) and incubated at 35ºC for 24 hrs. After appropriate serial dilutions, the homogenates were pour?plated on TCBS agar (Oxoid Ltd., Hampshire, England). Different NaCl concentrations (3, 5, 10 and 15%) were used to confirm growth of the suspected different types of Vibrio isolates for biochemical tests. Dilutions made for TBC were spread?plated on mannitol salt agar (MSA) (Oxoid Ltd., Hampshire, England). Typical yellow colonies were counted after 48 hrs of incubation at 35ºC. Biochemical tests were done according to the manual for general bacteriology of the American Society of Microbiology. Biochemical tests done were as follows: Oxidase test, catalase test, carbohydrate fermentation/utilization test, Kligler’s iron agar (KIA) test, indole production test, methyl red (MR) test, Voges?Proscauer (VP) test, citrate utilization test, nitrate reduction test, motility indole urea (MIU) test, and salt tolerance (3, 5, 10 and 15% NaCl) test were performed to identify the bacteria of interest. Susceptibility of E. coli, Salmonella, Shigella, Vibrio and Staphylococcus isolates to different antimicrobial agents was measured in vitro according to Kirby?Bauer methods(12). Commercially available 12 antimicrobial discs [ampicillin (AMP), amoxicillin (AML) bacitracin (B), chloramphenicol (C), ciprofloxacin (CIP), erythromycin (E), gentamycin (GN), penicillin G (PG), streptomycin (S), tetracycline (TE), penicillin (P) and kanamycin (K)] were used for the test. The E. coli, Salmonella?Shigella, and Staphylococcus isolates were used against the antibiotics. Statistical analysis was performed with the SPSS software package (Verson 11.5, SAS Institute Inc., Cary, USA). Tukey’s HSD post hoc for the multiple comparisons was followed with the level of significance to present the data as mean ± SEM.