Ultra high temperature (UHT) treated milk products and formula milk are known to be
frequently contaminated with Bacillus cereus. Presence of B. cereus in these milk products is
of particular concern considering the majority of consumers are infants and children. Possible
sources of contamination are contaminated raw milk, cross-contamination during processing,
under-processing and mishandling of milk products. This study was conducted to detect the
presence of B. cereus in both formula milk (n=12) and UHT milk (n=20) sold in selected retail
markets. The approach consisted of enumerating by MPN/g followed by PCR assay aimed
at detecting gyrB gene in B. cereus, that encode for the subunit B protein of DNA gyrase
(topoisomerase type II). Contamination level of B. cereus in both types of samples examined
ranged from < 3 to > 1100 MPN/g. The contamination level of B. cereus was found to be
highest in full cream UHT milk (> 1100 MPN/g) and formula milk (> 1100 MPN/g). The PCR
analysis showed that 41.7% (5/12) formula milk and 30% (6/20) UHT milk samples were
detected with B. cereus, respectively. This is the first report of such study demonstrating the
presence of B. cereus in formula milk from Malaysia. Therefore, constant surveillance of these
milk products would reduce the potential risk of B. cereus-linked outbreaks.
Bacillus cereus is a soil inhabitant gram positive bacterium, and is known to cause severe food poisoning. The objective of this study was to isolate and identify the presence of Bacillus cereus s.l. from selected ready to eat cereals purchased randomly from local supermarkets in Kuching and Kota Samarahan, Sarawak. The result showed that four of the 30 food samples were detected to be contaminated by B. cereus s.l. . Our findings suggested that it is important for the public to be aware of the safety of RTE cereals consumption, as it is possible that B. cereus s.l. may be present in high count number and pose hazardous health effects to the consumers.
This study was conducted to detect the presence of Listeria monocytogenes (L. monocytogenes)
and screen for its antibiotic susceptibility characteristic from wildlife and water samples at
Kubah National Park, Sarawak, Malaysia. Samples collected were incubated and streaked on
selective medium PALCAM agar to confirm the presence of Listeria spp. before they were
further tested using molecular analysis. Specific Polymerase Chain Reaction (PCR) assay were
performed to target specific virulence gene, haemolysin gene, hlyA to further distinguish the
presence of this pathogenic bacteria in the samples. Overall, out of the 30 samples tested, 10
samples were confirmed as to contain L. monocytogenes strains and selected to subsequent
antibiotic susceptibility test. Susceptibility patterns to 10 antibiotics were investigated
among the L. monocytogenes strains. All strains were uniformly resistant to tetracycline and
erythromycin. On the other hand, all strains were sensitive to gentamycin and tobramycin. The
multiple antibiotic resistance shown by the strains in this study indicate the potential health
hazard associated with the possible transmission between wildlife and water to its surrounding
environment especially visitors and workers of Kubah National Park, Sarawak, Malaysia.
(GTG)5 PCR is a type of repetitive extragenic palindromic (rep)-PCR which amplifies the (GTG)5 repetitive element that lays throughout the bacterial genome. In this study, fifty, thirty-nine and forty-nine unknown bacteria were isolated from aquaculture farms in Miri, Limbang and Lundu, respectively. (GTG)5 PCR was used to screen for clonal diversity among the isolates according to sampling sites. Banding profiles obtained from electrophoresed (GTG)5 PCR products were analyzed by RAPDistance Software to generate a dendrogram of neighbor joining tree (NJT) format. Based on the constructed dendrogram, representative isolates were selected for further identification. Conserved 16S rRNA region of the selected bacteria isolates were amplified and purified DNA products were sequenced. (GTG)5 PCR is useful in differentiation of unknown bacterial isolates and 16S rRNA analysis species identity of the bacteria in Sarawak aquaculture environment. The high diversity of bacteria in aquaculture environment may be caused by contamination from various sources.
The administration of antimicrobials in aquaculture provides a selective pressure creating a reservoir of multiple resistant bacteria in the cultured fish and shrimps as well as the aquaculture environment. The objective of this study was to determine the extent of antibiotic resistance in aquaculture products and aquaculture's surrounding environment in Sarawak, Malaysian Borneo. Ninety-four identified bacterial isolates constituted of 17 genera were isolated from sediment, water, and cultured organisms (fish and shrimp) in selected aquaculture farms. These isolates were tested for their antibiotic resistance against 22 antibiotics from several groups using the disk diffusion method. The results show that the highest resistance was observed towards streptomycin (85%, n = 20), while the lowest resistance was towards gentamicin (1.1%, n = 90). The multiple antibiotic resistant (MAR) index of the isolates tested ranged between 0 and 0.63. It was suggested that isolates with MAR index > 0.2 were recovered from sources with high risk of antibiotic resistant contamination. This study revealed low level of antibiotic resistance in the aquaculture bacterial isolates except for streptomycin and ampicillin (>50% resistance, n = 94) which have been used in the aquaculture industry for several decades. Antibiotic resistant patterns should be continuously monitored to predict the emergence and widespread of MAR. Effective action is needed to keep the new resistance from further developing and spreading.