Assessment of bacteriological quality and Escherichia coli O157: H7 in ready-to-eat street foods

Ready-to-eat (RTE) street foods are usually prepared well in advance (4-8 hrs) before the sale. Owning to minimal cooking procedures, cross-contaminations, and abused holding temperature and time, there is a high probability for deteriorating microbiological quality in these foods. Thus, this study was aimed to assess the bacteriological quality of RTE foods sampled from night markets and street stalls based on the guidelines provided by the Public Health Laboratory Service. A total of fifty samples (category 2, 3 and 4) were evaluated for aerobic colony count, total coliform, and E. coli. The pathogenic strain E. coli O157: H7 were examined using the multiplex PCR technique. It was noticed that category 3 and 4 RTE street foods were largely unsatisfactory for the coliform (&gt;104 CFU/ mL) and E. coli count (&gt;100 CFU/mL). In opposite, category 2 RTE street foods were unsatisfactory for the aerobic colony count (&gt;105 CFU/mL) and E. coli (&gt;100 CFU/ mL). However, there was no E. coli O157: H7 or Shiga-toxin producing bacteria reported in this study. The statistical analysis showed that in overall, category 3 and 4 RTE street foods were significantly at worsening bacteriological quality compared to category 2. Strict legal enforcement and amending the existing rules are needed to improve the quality of RTE street foods sold in the night markets and street stalls.</jats:p

Multiplex touchdown Polymerase Chain Reaction for rapid detection of Salmonella enterica subsp. enterica serovars Enteritidis and Typhimurium in food

The Salmonella outbreak is one of the leading foodborne diseases in the world with increasing cases being reported annually. However, the current methods for Salmonella detection in foods are outdated, laborious and time-consuming. This necessitated developing a technique that is rapid for Salmonella detection in foods. Thus, the current study aimed to develop a multiplex touchdown PCR (m-TdPCR) protocol for rapid and simultaneous detection of Salmonella enterica subsp. enterica serovars Enteritidis and Typhimurium in foods. A two-phase m-TdPCR protocol was developed and optimized with primer pairs targeting the Salmonella enterica subsp. enterica (ST11/ST15-0.15 µM), serovars Enteritidis (sdfI gene-1.2 µM), Typhimurium (fliC gene-1.5 µM) and an internal amplification control (16S rRNA-0.08 µM). It was found that the m-TdPCR protocol is highly sensitive detecting up to 1 ng of Salmonella DNA and its specificity was verified using the in-silico method. Furthermore, the developed m-TdPCR shows no non-specific PCR amplicons and is able to detect both S. enterica ser. Enteritidis and S. enterica ser. Typhimurium in real-time when tested against the artificially contaminated food samples at up to 10-3 dilutions. Therefore, the validated m-TdPCR protocol in this study can be used as a tool for rapid detection of S. enterica ser. Enteritidis and S. enterica ser. Typhimurium in food samples and this may significantly reduce any related foodborne incidences in future.</jats:p

Multiplex touchdown polymerase chain reaction for rapid detection of Salmonella enterica subsp. enterica serovars Enteritidis and Typhimurium in food

The Salmonella outbreak is one of the leading foodborne diseases in the world with increasing cases being reported annually. However, the current methods for Salmonella detection in foods are outdated, laborious and time-consuming. This necessitated developing a technique that is rapid for Salmonella detection in foods. Thus, the current study aimed to develop a multiplex touchdown PCR (m-TdPCR) protocol for rapid and simultaneous detection of Salmonella enterica subsp. enterica serovars Enteritidis and Typhimurium in foods. A two-phase m-TdPCR protocol was developed and optimized with primer pairs targeting the Salmonella enterica subsp. enterica (ST11/ST15-0.15 µM), serovars Enteritidis (sdfI gene-1.2 µM), Typhimurium (fliC gene-1.5 µM) and an internal amplification control (16S rRNA-0.08 µM). It was found that the m-TdPCR protocol is highly sensitive detecting up to 1 ng of Salmonella DNA and its specificity was verified using the in-silico method. Furthermore, the developed m-TdPCR shows no non-specific PCR amplicons and is able to detect both S. enterica ser. Enteritidis and S. enterica ser. Typhimurium in real-time when tested against the artificially contaminated food samples at up to 10-3 dilutions. Therefore, the validated m-TdPCR protocol in this study can be used as a tool for rapid detection of S. enterica ser. Enteritidis and S. enterica ser. Typhimurium in food samples and this may significantly reduce any related foodborne incidences in future. © 2023 The Authors. Published by Rynnye Lyan Resources

Multiple antibiotic-resistant Salmonella enterica serovars Enteritidis and Typhimurium in ready-to-eat battered street foods, and their survival under simulated gastric fluid and microwave heating

Cooked battered products like nuggets and sausages are famous street foods in Malaysia. However, these foods lack prevalence data for the non-typhoidal Salmonella enterica serovars Enteritidis and Typhimurium (NTS) contaminations, thus leading to concern over foodborne outbreaks. Therefore, the present work aimed to examine the prevalence of antibiotic-resistant NTS in battered foods, and investigate their survival under simulated gastric fluid (SGF) and microwave heating. Food samples (n = 312) were homogenized, prepared in triplicate tubes (10−1, 10−2, 10−3), and subjected to a combined most probable number (MPN) statistical analysis and multiplex-touchdown PCR amplification for NTS detection. The tubes with bacterial growth were cultured on Xylose Lysine Deoxycholate (XLD) agar, and isolated NTS were subjected to antibiotic susceptibility (disk diffusion) and survival tests in SGF (pH: 2.0, 3.0, 4.0, and 7.0) and microwave heating. Results showed that S. Enteritidis and Typhimurium contaminated 5.1% and 1.6% of battered foods, respectively. Pork sausage yielded the highest S. Enteritidis concentration (150 MPN/g), and beef sausage yielded the highest S. Typhimurium (28 MPN/g) concentration. Four S. Enteritidis and one S. Typhimurium strains exhibited multiple antibiotic resistance to cefazolin, ampicillin, streptomycin, tetracycline, sulfonamides, nalidixic acid, kanamycin, gentamycin, and chloramphenicol. The NTS strains were also resistant to SGF at all tested pH, but inactivated at microwave heating (700W, 2.45Hz, 60 s). These indicated that NTS contamination in cooked battered foods was low. However, multiple antibiotics and SGF resistance might imply severe consequences if proper interventions were not taken