1.Prevalence of virulent resistant Salmonella enterica strains from sushi and sashimi samples in Malaysia
Suat Moi Puah ; Kek Heng Chua ; Jin Ai Mary Anne Tan
Tropical Biomedicine 2016;33(3):476-485
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.
2.Prevalence of Staphylococcus aureus and Salmonella enterica in ready-to-eat sushi and sashimi
Suat Moi Puah ; Kek Heng Chua ; Jin Ai Mary Anne Tan
Tropical Biomedicine 2017;34(1):45-51
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.
3.Molecular characterisation of Haemoglobin Constant Spring and Haemoglobin Quong Sze with a Combine-Amplification Refractory Mutation System
Yong-Chui Wee ; Kim-Lian Tan ; Kek-Heng Chua ; Elizabeth George ; Jin-Ai Mary Anne Tan
Malaysian Journal of Medical Sciences 2009;16(3):23-30
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.