Screening the Microbiological Contamination in Salad Samples and Analysis their Antibiotic Sensitivity Pattern

Salad is often consumed fresh and thus can act as effective media for the transmission of associated pathogens. This investigation was carried out to determine the microbiological quality of salad. A total twenty-five samples were collected from twenty different area of Dhaka city. Samples were collected from chines restaurants, fast food centers, café, and roadside shops. According to the place of preparation samples were classified into three category such as A (chines and fast food), B (café), C (road side shop). Samples from each category of salad were prepared to determine the total bacterial count, total coliform count and highlighted the presence of pathogenic microorganisms such as E. coli, Staphylococcus aureus, Salmonella spp. by standard microbiological methods. The total viable bacterial count ranged from 0.3 × 10³ to 8.3 × 10⁷ cfu/g. The coliform and fecal coliform ranged from <0.4 MPN/gm to >240 MPN/gm and Staphylococcus spp. ranged from 0.5 ×103 to 1.25 ×104 cfu/g. Rates of contamination in relation to the various sources were: samples from A- category 71.4%, B- category 87.5% and C- category 90%. Antimicrobial susceptibility was also determined for the isolated microorganisms. Amoxicillin (10 µg), ciprofloxacin 5 µg), ceftazidime (30 µg), tetracycline (30 µg), gentamicin (10 µg), trimethoprim-sulfamethoxazole (23.75 µg), were used for antibiotic susceptibility testing. 100% Salmonella spp. was resistant to amoxicillin whereas E. coli was 80%. But both strains were 100% sensitive to ciprofloxacin, gentamicin, tetracycline. The results of the study demonstrate that salads available in chines restaurant, fast food center, café and road side shop are contaminated with pathogenic bacteria which are potential health threat to consumers. Maintaining personal hygiene, pre-processing disinfection and proper storage temperatures will be useful to minimize the unhygienic and health risks.