Prevalence and quantification of Listeria monocytogenes in beef offal at retail level in Selangor, Malaysia

A total of 63 beef offal samples (beef liver = 16; beef lung = 14; beef intestine = 9; beef tripe = 15; beef spleen = 9) from three wet markets (A, B, and C) in Selangor, Malaysia were examined for the prevalence and microbial load of Listeria monocytogenes. A combination of the most probable number and polymerase chain reaction (MPN-PCR) method was employed in this study. It was found that L. monocytogenes detected in 33.33% of the beef offal samples. The prevalence of L. monocytogenes in beef offal purchased from wet markets A, B, and C were 22.73%, 37.50% and 41.18% respectively. The density of L. monocytogenes in all the samples ranged from<3upto> 2,400 MPN/g. The findings in this study indicate that beef offal can be a potential vehicle of foodborne listeriosis.

Examination of diarrheal stools in Hat Yai City, South Thailand, for Escherichia coli O157 and other diarrheagenic Escherichia coli using immunomagnetic separation and PCR method.

A total of 493 stool samples from diarrheal patients in Songklanagarind Hospital, in southern Thailand, were examined for Escherichia coli O157 by the culture method combined with an immunomagnetic separation (IMS) technique. E. coli O157 was not found, although the IMS-based method could detect 10(2)-10(3) CFU of artificially inoculated O157/g of stool samples. Polymerase chain reaction was also used for the detection and identification of diarrheagenic E coli from 530 stool samples. The target genes were eae for enteropathogenic E. coli (EPEC), stx for enterohemorrhagic E. coli (EHEC), elt and est for enterotoxigenic E. coli (ETEC), ipaH for enteroinvasive E. coli (EIEC), and aggR for enteroaggregative E. coli (EAggEC). Fifty-eight diarrheagenic E. coli strains were detected in 55 stool samples (10%) from 32 children and 23 adults. These included 31 EAggEC strains (5.8%), 13 ETEC strains (2.5%), 13 EPEC strains (2.5%), and one EIEC strain (0.2%). EHEC was not detected. The diarrheagenic E. coli strains were found mainly in children under 2 years of age (24 of 32 children). EAggEC strains and ETEC strains were susceptible to several antibiotics whereas the EPEC strains exhibited resistance to these antibiotics.

Detection of tdh and trh genes in Vibrio parahaemolyticus isolated from Corbicula moltkiana prime in West Sumatera, Indonesia.

The occurrence of Vibrio parahaemolyticus in raw Corbicula moltkiana Prime from Lake Singkarak and Pasar Raya Padang market and in cooked samples in West Sumatera, Indonesia, was studied. Thirteen raw and seven cooked bivalve samples were positive using CHROMAgar Vibrio medium. All 47 V parahaemolyticus isolates were positive for toxR gene but negative for trh. However, 36% (17/47) of V parahaemolyticus strains were positive for tdh gene. Antibiotic profiling showed that 76% and 38% of isolates from raw and cooked bivalves respectively were resistant to ampicillin. Using RAPD-PCR analysis, most of the strains were clustered according to their source of isolation but some of the strains from raw and cooked samples were clustered together. These results indicate that pathogenic V parahaemolyticus isolates are present in Corbicula moltkiana Prime in West Sumatera, Indonesia, suggesting that V parahaemolyticus may also be present in seafood in other regions of Indonesia.

Characterization of vibrio parahaemolyticus isolated from coastal seawater in peninsular Malaysia.

Twenty-one Vibrio parahaemolyticus isolates representing 21 samples of coastal seawater from three beaches in peninsular Malaysia were found to be sensitive to streptomycin, norfloxacin and chloramphenicol. Resistance was observed to penicillin (100%), ampicillin (95.2%), carbenicilin (95.2%), erythromycin (95.2%), bacitracin (71.4%), cephalothin (28.6%), moxalactam (28.6%), kanamycin (19.1%), tetracycline (14.3%), nalidixic acid (9.5%) and gentamicin (9.5%). Plasmids of 2.6 to 35.8 mDa were detected among plasmid-containing isolates. All isolates carried the Vp-toxR gene specific to V. parahaemolyticus and were negative for the tdh gene, but only one isolate was positive for the trh gene. DNA fingerprinting of the isolates using ERIC-PCR and PFGE showed that the isolates belong to two major clonal groups, with several isolates from different locations in the same group, indicating the presence of similar strains in the different locations.