Search Results (3)

Salmonella enteritidis is a major causative agent of foodborne illnesses worldwide. As the traditional serotyping and quantification methods are labor-intensive, time-consuming, and expensive, faster and more convenient molecular diagnostic methods are needed. In this study, we developed and validated a rapid duplex TaqMan real-time polymerase chain reaction (PCR) for the accurate identification and quantification of S. enteritidis. The primers and TaqMan probes were designed based on the S. enteritidis-specific gene lygD and the Salmonella genus-specific gene invA. The melt curve and gel electrophoresis analysis showed that the designed primers had potent specificity for the amplification of lygD and invA. The duplex real-time PCR specifically identified S. enteritidis from a panel of 40 Salmonella strains that represented 29 serovars and 12 non-Salmonella organisms. The duplex real-time PCR assay detected four copies of S. enteritidis DNA per reaction. The intra- and inter- assays indicated a high degree of reproducibility. The real-time PCR could accurately detect and quantify S. enteritidis in chicken organs after Salmonella infection. Furthermore, the assay identified 100% of the S. enteritidis and Salmonella genus isolates from chicken egg samples with superior sensitivity after 6 h of pre-enrichment compared to the traditional culture method. Additionally, the most-probable-number (MPN) combined with qPCR and a shortened incubation time (MPN-qPCR-SIT) method was developed for the population determination of S. enteritidis and compared with various enumeration methods. Thus, we have established and validated a new duplex real-time PCR assay and MPN-qPCR-SIT method for the accurate detection and quantification of S. enteritidis, which could contribute to meeting the need for fast detection and identification in prevention and control measures for food safety. Full article

The prevalence of antimicrobial resistance has drawn the public’s attention worldwide. The presence of ESBL E. coli in fresh produce and other food represents a growing problem involving food safety and has become a global food safety issue. This study was aimed to determine the prevalence of ESBL-producing E. coli in raw vegetables (lettuce and bean sprouts) from hypermarkets and wet markets and to establish the antibiogram of the isolates. In this study, a total of 180 samples (95 samples of lettuce and 85 samples of bean sprouts) were collected from hypermarkets and wet markets. The most-probable-number analysis and multiplex polymerase chain reaction (MPN–PCR) was used to detect and quantify the ESBL-producing E. coli in raw vegetable samples. The prevalence rates of ESBL-producing E. coli in lettuce and bean sprouts were 62.11% (59/95) and 63.53% (54/85), respectively, with a microbial load range of <3 to >1100 MPN/g. A total of 15 isolates of ESBL-producing E. coli recovered from the samples were tested with an antibiotic susceptibility test (AST) with different antibiotic classes. All isolates were found to be susceptible to cefepime, piperacillin/tazobactam, and meropenem. A total of nine ESBL-producing E. coli strains showed multidrug resistance. In conclusion, the high prevalence rate of ESBL-producing E. coli in raw vegetables showed that raw vegetables could act as a potential vehicle to transmit ESBL-producing E. coli to the human population. Full article

The estuary is the ecological niche of pathogenic Vibrio spp. as it provides abundant organic and inorganic nutrients from seawater and rivers. However, little is known about the ecology of these Vibrio species in the inland brackish water area. In this study, their co-occurrence and relationships to key environmental constraints (salinity and temperature) in the Hun-Tai River of China were examined using the most probable number polymerase chain reaction (MPN-PCR) approach. We hereby report 2-year continuous surveillance based on six water indices of the Hun-Tai River. The results showed that seawater intrusion maximally reached inland as far as 26.5 km for the Hun-Tai River. Pathogenic Vibrio spp. were detected in 21.9% of the water samples. In particular, V. cholerae, V. parahaemolyticus, and V. vulnificus were isolated in 10 (10.4%), 20 (20.8.5%), and 2 (2.08%) samples, respectively. All V. parahaemolyticus strains were tdh gene negative, 10% were positive for the trh gene. Multi-locus sequence typing (MLST) divided V. parahaemolyticus strains into 12 sequence types (STs) for the Hun-Tai River. Five STs were respectively present in various locations along the Hun-Tai River. The PCR assay for detecting six virulence genes and Vibrio seventh pandemic island I and II revealed three genotypes in 12 V. cholerae isolates. The results of our study showed that seawater intrusion and salinity have profound effects on the distribution of pathogenic Vibrio spp. in the inland river, suggesting a potential health risk associated with the waters of the Hun-Tai River used for irrigation and drinking. Full article