Prevalence of Staphylococcus aureus and Salmonella enterica in ready-to-eat sushi and sashimi

Abstract. Staphylococcus aureus food poisoning and Salmonellosis outbreaks have been associated with two popular ready-to-eat items: sushi and sashimi. Thus this study aims to determine the prevalence of S. aureus and S. enterica in sushi and sashimi in Malaysia. Sushi (149) and sashimi (51) were collected from 14 retail outlets comprising supermarkets, hypermarkets, restaurants and open-air night markets. Bacterial isolation was carried out using Baird-Parker and CHROMagar Salmonella Plus selective media. The food pathogens isolated from microbiological media were then confirmed by molecular analysis. The results confirmed an overall S. aureus and S. enterica contamination of 42% (84/200) in the sushi and sashimi samples. Regarding prevalence of the individual pathogens involved, S. aureus was detected in 26% (52/200) and S. enterica in 16% (32/200) of the contaminated samples. This study demonstrates a high occurrence rate of S. aureus and S. enterica in sushi and sashimi foods in Malaysia, and warrants the necessity to monitor the microbiological process of RTE foods to ensure food safety for consumers.

Prevalence of virulent resistant Salmonella enterica strains from sushi and sashimi samples in Malaysia

Salmonella enterica is one of the leading causes of human foodborne infections. The objectives of this study are to investigate S. enterica prevalence in sushi and sashimi in Malaysia, to determine the presence of virulence genes and the antimicrobial resistance profiles of isolated S. enterica. In the 200 samples tested, 16% were positive for S. enterica. Sixty-six percent of the S. enterica isolates harboured at least one virulence gene and the most common virulence gene was sifA (37.5%). Antibiotic susceptibility testing showed 65.6% (21/32) of the isolates to be resistant to at least one antibiotic tested, with sulfamethoxazole resistance as the most common (50%). Resistance to the drugs-of-choice (fluoroquinolones and third-generation cephalosporin) for severe salmonellosis were also detected – ceftriaxone (25%), ceftazidime (28.1%) and ciprofloxacin (9.4%). Two isolates (9.5%) were resistant to all antibiotic tested while 12 isolates (37.5%) exhibited multi-drug resistance (MDR) with 10 different MDR profiles. Most of the isolates presented MDR profilesAP, AUG, FOX, NA (penicillins, beta-lactams, cephems and quinolone) with or without the addition of other drugs. In conclusion, the high rate of S. enterica prevalence in the sampled sushi and sashimi warrants increased safety measures for sushi and sashimi preparation.

Dystrophin gene analysis in Duchenne/Becker dystrophy in a Malaysian population using multiplex polymerase chain reaction

Dystrophinopathy is the commonest form of muscular dystrophy and comprises clinically recognized forms, Duchenne dystrophy and Becker dystrophy. Mutations in the dystrophin gene which consist of large gene deletions (65%), duplications (5%) and point mutations (30%) are responsible for reducing the amount of functional dystrophin protein in skeletal muscle fi bres leading to fi bre destruction and disease. The aims of this study are to investigate the detection rate, types and distribution of large gene deletions in Malaysian dystrophinopathy patients using the multiplex polymerase chain reaction (MPCR). MPCR of 18 “hot-spot deletion” regions along the dystrophin gene was performed on DNA from 48 muscle biopsy-confi rmed cases of dystrophinopathy. A positive detection rate of 58% (28/48) was observed, where 84% (16/19) Indian, 35% (6/17) Chinese and 50% (6/12) Malay ethnic groups showed deletions in their dystrophin genes. The Malaysian Indians appear to have a higher prevalence for large gene deletions compared to the Chinese and Malays. Further analyses of 42 confi rmed positive cases (present 28 plus previous 14 cases) by MPCR showed the majority of deletions were in the mid-distal region of the dystrophin gene (81% in exons 45-60). The MPCR is a specifi c and sensitive method for confi rmation of gene deletions responsible for dystrophinopathy.

Molecular characterisation of Haemoglobin Constant Spring and Haemoglobin Quong Sze with a Combine-Amplification Refractory Mutation System

@#Background: The interaction of the non-deletional α+-thalassaemia mutations Haemoglobin Constant Spring and Haemoglobin Quong Sze with the Southeast Asian double α-globin gene deletion results in non-deletional Haemoglobin H disease. Accurate detection of non-deletional Haemoglobin H disease, which is associated with severe phenotypes, is necessary as these mutations have been confirmed in the Malaysian population. Methods: DNA from two families with Haemoglobin H disease was extracted from EDTAanticoagulated whole blood and subjected to molecular analysis for α-thalassaemia. A duplex polymerase chain reaction was used to detect the Southeast Asian α-globin gene deletion. Polymerase chain reaction-restriction fragment length polymorphism analysis was then carried out to determine the presence of Haemoglobin Constant Spring and Haemoglobin Quong Sze. A combine- amplification refractory mutation system protocol was optimised and implemented for the rapid and specific molecular characterisation of Haemoglobin Constant Spring and Haemoglobin Quong Sze in a single polymerase chain reaction. Results and Conclusions: The combine- amplification refractory mutation system for Haemoglobin Constant Spring and Haemoglobin Quong Sze, together with the duplex polymerase chain reaction, provides accurate pre- and postnatal diagnosis of non-deletional Haemoglobin H disease and allows detailed genotype analyses using minimal quantities of DNA.

Molecular characterisation and frequency of Ggamma Xmn I polymorphism in Chinese and Malay beta-thalassaemia patients in Malaysia

The molecular basis of variable phenotypes in P-thalassaemia patients with identical genotypes has been associated with co-inheritance of alpha-thalassaemia and persistence of HbF production in adult life. The Xmn I restriction site at -158 position of the Ggamma-gene is associated with increased expression of the Ggamma-globin gene and higher production of HbF This study aims to determine the frequency of the digammaferent genotypes of the Ggamma Xmn I polymorphism in P-thalassaemia patients in two ethnic groups in Malaysia. Molecular characterisation and frequency of the Ggamma Xmn I polymorphism were studied in fifty-eight Chinese and forty-nine beta-thalassaemia Malay patients by Xmn I digestion after DNA amplification of a 650 bp sequence. The in-house developed technique did not require further purification or concentration of amplified DNA before restriction enzyme digestion. The cheaper Seakem LE agarose was used instead of Nusieve agarose and distinct well separated bands were observed. Genotyping showed that the most frequent genotype observed in the Malaysian Chinese was homozygosity for the absence of the Xmn I site (-/-) (89.7%). In the Malays, heterozygosity of the Xmn I site (+/-) was most common (63.3%). Homozygosity for the Xmn I site (+/+) was absent in the Chinese, but was confirmed in 8.2% of the Malays. The ratio of the (+) allele (presence of the Xmn I site) to the (-) allele (absence of the Xmn I site)) was higher in the Malays (0.66) compared to the Chinese (0.05). The (+/-) and (+/+) genotypes are more commonly observed in the Malays than the Chinese in Malaysia.