Isolation, identification, and antibiogram studies of Escherichia coli from ready-to-eat foods in Mymensingh, Bangladesh.

Background and Aim: Ready-to-eat (RTE) foods are widely used at home, restaurants, and during festivals in Bangladesh. So it is very important to investigate possible microbial contamination in RTE foods. Therefore, this study aimed to determine the total coliform count (TCC), isolate, identify, and characterize the Escherichia coli in RTE foods. The antimicrobial sensitivity of E. coli obtained from RTE foods was also performed using 12 commonly used antibiotics. Materials and Methods: A total of 100 RTE food samples were collected aseptically and comprised of ten samples each: Burger, pizza, sandwich, chicken roll, chicken meat loaf, chicken fry, salad vegetable, ice-cream, yogurt, and milkshake sold in Mymensingh City. Samples were inoculated onto Eosin methylene blue agar and incubated at 37°C for 24 h. Isolation and identification of bacteria were performed based on cultural, staining, and biochemical properties, followed by a polymerase chain reaction. Results: The TCC in Chicken meat loaf, burger, pizza, sandwich, salad vegetable ice-cream, and yogurt samples were 3.57 ± 0.96, 3.69 ± 0.08, 3.50 ± 0.60, 2.60 ± 0.20, 4.09 ± 0.29, 4.44 ± 0.25, and 3.14 ± 0.30 mean log colony-forming units ± standard deviation/mL, respectively. The study found a higher prevalence of E. coli in RTE salad vegetable products than in RTE meat and milk products. Forty percent of the mixed vegetable salad samples showed positive results for E. coli. Whereas E. coli prevalence in RTE meat and milk products was 20% and 16.7%, respectively. All the 21 isolates were subjected to antibiotic susceptibility test against 12 different antibiotics. It was observed that 46.1% were susceptible, 16.6% were intermediate, 46.1% were resistant, and 47.6% were multidrug-resistant (MDR) among seven different antibiotic classes. E. coli isolates were resistant to cephalexin, ceftazidime, oxytetracycline, and ampicillin and sensitive to gentamycin, followed by kanamycin, ceftriaxone, colistin, and enrofloxacin. Conclusion: The study revealed that RTE foods are a serious issue from a public health point of view. To achieve a safer level of E. coli in RTE foods sold for human consumption, public food outlets must improve hygienic and good production procedures. Moreover, MDR E. coli in these foods pose serious public health threats.

Multidrug-resistant Staphylococcus aureus isolated from chicken nuggets sold at superstores in Mymensingh, Bangladesh.

Objective: This study was conducted to determine the colony forming units (CFU) to isolate, identify, and antibiotic sensitivity of Staphylococcus aureus from chicken nuggets (CN). Materials and Methods: Sixty CN samples from two brands were collected from different superstores in Mymensingh, Bangladesh. Uncooked, oven-cooked (OC), or gas stove-cooked (GSC) CN samples were inoculated onto mannitol salt agar and blood agar. Results: The total staphylococcal count (TSC) for uncooked CN ranged from log 4.68 to log 5.11 CFU/gm. For OC CN, TSC ranged from log 3.29 to log 3.62 CFU/gm. For GSC CN, TSC ranged from log 3.09 to log 3.49 CFU/gm. Relative to uncooked CN, microwave oven-cooked and GSC samples significantly reduced the TSC of CN (p < 0.01). Using the polymerase chain reaction assay and standard biochemical testing, only 8 out of 60 CN samples contained S. aureus. Staphylococcus aureus were resistant to Ampicillin (100%), Amoxicillin (100%), Oxacillin (75%), Cefixime (87.5%), Doxycycline (75%), intermediately sensitive to Erythromycin (25%), Cephalexin (12.5%), Ciprofloxacin (25%), Gentamicin (12.5%), Doxycycline (12.5%) and sensitive to Oxacillin (25%), Azithromycin (100%), Erythromycin (75%) Cephalexin (87.5%), Cefixime (12.5%), Chloramphenicol (100%), Ciprofloxacin (75%), Gentamicin (87.5%), Doxycycline (12.5%), and Vancomycin (100%). Conclusion: This study reports the first isolation and identification of S. aureus from CN in Bangladesh. GSC CN was better than OC and uncooked CN. Data also suggest that CN is contaminated with multidrug-resistant S. aureus, which poses a public health hazard.

Isolation and identification of bacteria from fresh guava (Psidium guajava) sold at local markets in Mymensingh and their antibiogram profile.

AIM: The study was conducted for the isolation, identification, and antibiogram of bacteria obtained from fresh guava (Psidium guajava). MATERIALS AND METHODS: A total of 25 fresh guavas were collected from five markets located in Mymensingh city. Guava samples were cultured onto various selective media such as eosin methylene blue, xylose lysine deoxycholate, thiosulfate-citrate-bile salts-sucrose, blood agar, and mannitol salt agar for the isolation of bacteria. Biochemical tests (dextrose, maltose, lactose, sucrose, mannitol, methyl red, Voges-Proskauer, and indole) were performed to identify the bacteria. RESULTS: Total viable counts of guava were ranged between log 6.56 colony-forming unit (cfu)/ml and 6.62 cfu/ml. A total of 106 bacterial isolates belonged to five genera (Escherichia coli, Salmonella spp., Vibrio spp., Bacillus spp., and Staphylococcus spp.) were identified. Salmonella spp. (23.6%) was the most prevalent, followed by E. coli (22.64%), Bacillus spp. (19.81%), Staphylococcus spp. (17.92%), and Vibrio spp. (16.03%). The results of antibiotic sensitivity test showed that Salmonella spp., Bacillus spp., and E. coli were sensitive to chloramphenicol, ciprofloxacin, and gentamicin and resistant to ampicillin and cephalexin. Vibrio spp. was sensitive to chloramphenicol and gentamicin, intermediately sensitive to ciprofloxacin and ampicillin and resistant to cephalexin. CONCLUSION: The results of this study indicate that fresh guava contains multidrug-resistant bacteria which might pose a public health risk.