Listeria infection is caused by consuming food containing L. monocytogenes which is contaminated from environment. Therefore, the cleanliness and hygiene maintained in the factory are the utmost importance in controlling L. monocytogenes. VIDAS UP Listeria is an automated rapid detection kit of Listeria genus in food and environmental samples. In this study, VIDAS UP Listeria and a selective medium, LPT Broth, were evaluated. The maximum growth rate and OD of L. monocytogenes in LPT Broth were compared with those in half Fraser Broth with no added ammonium iron(III) citrate or Fraser Broth with no added ammonium iron(III) citrate. The maximum growth rate of LPT Broth was 3.0 to 6.3 times faster than other medium. The maximum OD of LPT Broth was 2.4 to 2.9 times higher than other medium. In addition, the growth of Gram-negative bacteria such as Acinetobacter and Pseudomonas was inhibited in LPT Broth. The growth of L. monocytogenes was delayed in co-culture with Microbacterium arborescens and P. putida group. Negative correlation was detected between initial counts of these bacteria and the count of L. monocytogenes after co-culture. A long incubation time (26 to 30 hr) was suitable for detection of L. monocytogenes in environment samples. In conclusion, VIDAS UP Listeria was a powerful tool for the rapid detection of Listeria genus in environmental samples.
Selective plate media supplemented with potassium tellurite, such as sorbitol MacConkey agar with cefixime and potassium tellurite (CT-SMAC) are widely used for isolation of Shiga toxin-producing Escherichia coli (STEC), especially in major O serogroups including O157, O111, O26, O103, O121 and O145. However, there is little information in effectiveness of these plates for minor O-serogroup STEC strains. Here, we evaluated four types of commercial STEC selective plates (CT-SMAC, CHROMagar STEC, XM-EHEC and “KBM” EHEC Chromogenic Medium) using 152 various O-serogroups STEC strains, except for major O serogroups. As a result, 36 strains belonging to 16 O serogroups grew on all four types of plates, and PCR screening showed that all 36 carried the terA associated with tellurite resistance. Of these strains, 27 were eae-positive, and other 9 were eae-negative STEC. The STEC characteristics about the resistance to tellurite as well as the prevalence of the ter operon based on their O serogroups (or O genotypes) reported here may help to choose a suitable selective media on the investigation and the surveillance of STEC.
A beef cattle liver and swine liver were collected between July to November 2013 in Japan. Campylobacterjejuni and C. coli were isolated from 21.6% (109/505) of beef cattle liver and from 14.8% (74/500) of swine liver. A total of 184 Campylobacter isolates (109 beef cattle liver isolates and 75 swine liver isolates) were subjected to antimicrobial resistance profiling against eight different antimicrobials. Regarding antimicrobial resistance, C. jejuni (beef cattle liver isolates) and C. coli (swine liver isolates) showed resistance against 1 to 5 and 1 to 6 antimicrobial agent, respectively. For C. jejuni isolates, antimicrobial resistance rates were observed in 2.0% of EM and CP to 58.6% of TC. And for C. coli isolates, these were observed in 8.3% of CP to 84.7% of TC. Pulsed-field gel electrophoresis (PFGE) patterns were examined in Ciprofloxacin (CPFX) resistant strains. CPFX resistant C. jejuni and C. coli were classified into 17 different PFGE patterns and 19 patterns, respectively.
Enterohemorrhagic E. coli (EHEC) or Shiga toxin-producing E. coli is known as an important food-borne pathogen, and O157 is the most frequently reported O serogroups of EHEC strains associated with bloody diarrhea and hemolytic-uremic syndrome worldwide. Subsequently O26, O111, O103, O145, O121 and O165 serogroups of EHEC were also frequently isolated from patients with severe diseases in Japan. The O serogrouping of EHEC is essential in outbreak investigations and surveillance. In a previous study, we developed a comprehensive and practical platform for molecular O-serogrouping of E. coli strains, named as E. coli O-genotyping PCR (Iguchi, A., et al.: J. Clin. Microbiol., in press), targeting unique sequences on each O-antigen biosynthesis gene cluster. Based on the PCR system, we now developed an EHEC-specific multiplex PCR system, named as “MP-1 plus,” targeting seven major EHEC O serogroups and three virulence genes, stx1, stx2 and eae. This primer set contains 10 primer pairs that amplify products with different sizes, and validation studies using reference and wild strains showed that the results were reliable enough. The one-shot PCR method reported here might be a promising tool for the identification and subtyping of EHEC strains for outbreak investigations as well as for the surveillance.
We swabbed surfaces to detect the presence of Norovirus (NV) using bioluminescent enzyme immunoassay (BLEIA) and to assess the accuracy and usefulness of this method compared with the standard method of real-time PCR. All samples obtained were assessed via both methods. We determined that BLEIA was not only accurate and effective but also cheaper than real-time PCR. Moreover, the simultaneous processing of a large number of samples was easier using BLEIA. Therefore, we recommend the use of BLEIA to rapidly detect NV on a plethora of surfaces.