1.Synthesis, characterization, anti-mycobacterial activity and in silico study of new 2,5-disubstituted-1,3,4-oxadiazole derivatives
Azmi, M.N. ; Hasmaruddin, N.S. ; Mat Ali, N.A. ; Osman, H. ; Mohamad, S. ; Parumasivam, T. ; Hassan, M.Z. ; Abd Ghani, M.S. ; Awang, K.
Tropical Biomedicine 2022;39(No.3):467-475
A series of new 2,5-disubstituted-1,3,4-oxadiazole derivatives (5a-j and 6a-j) have been designed and
synthesized in four-steps. Sixteen compounds among the twenty compounds are reported for the first
time. The compounds were characterized and confirmed by the FTIR, 1D- and 2D-NMR and HRMS
analyses, and were tested against Mycobacterium smegmatis and Mycobacterium tuberculosis H37Ra.
Compound 5d was the most active against M. smegmatis with MIC value of 25 µM, and exhibited
cidal activity with MBC of 68 µM, respectively. The time-kill assay showed the good killing rate at 77%
with the combination of isoniazid (INH). In addition, checkboard assay confirmed the interaction of
compound 5d was categorised as additive. Docking simulation has been performed to position 5d into
the pantothenate synthetase active site with binding free energy value –8.6 kcal mol-1. It also occupied
the same active site as that of standard native ligand with similar interactions, which clearly indicate
their potential as pantothenate synthetase inhibitor.
2.Toxoplasma gondii infection among selected indigenous community in Sarawak, East Malaysia
Ngui, R. ; Hassan, N.A. ; Chang, L.Y. ; Teh, S.J.C. ; Chua, K.H. ; Kee, B.P. ; Hoe, S.Z. ; Lim, Y.A.L.
Tropical Biomedicine 2020;37(No.1):155-164
Toxoplasma gondii is an obligate intracellular protozoan parasite that causes toxoplasmosis in humans. To date, little is known about T. gondii infection among the indigenous community, particularly in East Malaysia. This study was conducted to determine the status of T. gondii infection and to investigate associated risk factors among the indigenous community of Sarawak, East Malaysia. The sociodemographic data was obtained using a pretested questionnaire. A serological test was done to detect the presence of specific IgM and IgG antibodies against T. gondii in serum samples. A nested polymerase chain reaction (PCR) was used to determine acute infection among seropositive individuals. The overall seroprevalence of T. gondii infection was 50% (95% CI = 43.3 – 56.7). From this subset, 40.1%, 5.7%, and 4.2% were positive for anti-T. Gondii IgG antibodies, IgM, and both IgG and IgM, respectively. Four seropositive samples were amplified through PCR. None of the pregnant women tested positive for T. gondii infection based on the serological and PCR assays. A significant association was found between age, low monthly household income, unemployment, usage of untreated water and close contact with T. gondii seropositive cats. These results provide basic information on T. gondii infection and may be useful for policymakers to initiate prevention and control programs, especially amongst pregnant women and women of childbearing age in the indigenous community.
3.Oral bacteria detection among children with cancer in a tertiary teaching hospital in Kuala Lumpur, Malaysia
Sidi Omar, S.F.N. ; Ngui, R. ; Ab Rahman, S.Z. ; Foo, J.C. ; Wang, Q.Y. ; Hassan, N.A. ; Lim, Y.A.L. ; Musa, S.
Tropical Biomedicine 2021;38(No.3):276-282
This study sought to determine the prevalence of pathogenic and non-pathogenic bacteria in the oral cavities of children with cancer. There were 68 paediatric patients with cancer who were included in this study. Oral swab samples from the dorsum of tongues and mouth floors of these patients were subjected to culture, staining, and molecular methods to detect the bacteria. The overall prevalence of gram-positive and gram-negative bacteria was 79.4% (54/68; 95% CI = 68.4 – 87.3) and 25% (17/68; 95% CI = 16.2 – 36.4), respectively. Streptococcus salivarius and Streptococcus parasanguinis were the predominant pathogenic grampositive bacteria, while Neisseria subflava and Neisseria perflava were the most common pathogenic gram-negative bacteria. The results revealed that the number of bacteria isolates recovered in patients receiving cancer treatment was higher (55.9%) than those who had not received treatment (16.2%). Therefore, more isolated pathogenic bacteria were observed post-therapy (54.4%). Pathogenic organisms can have significant implications on patient health. Awareness of the types of bacteria inhabiting the oral cavity is essential to predict and prevent dental problems, and their associated systemic complications. Findings on the diversity of oral microflora can also provide a better understanding of the aetiology of oral diseases in paediatric patients receiving cancer treatment.
4.A conventional multiplex PCR for the detection of four common soil-transmitted nematodes in human feces: development and validation
Hassan, N.A. ; Noor Badi, F.A. ; Mohd-Shaharuddin, N. ; Wan Yusoff, W.S. ; Lim, Y.A.L. ; Chua, K.H. ; Sidi Omar, S.F.N. ; Chang, L.Y. ; Majid, H.A. ; Ngui, R.
Tropical Biomedicine 2022;39(No.1):135-142
Soil-transmitted helminth (STH) infections, mainly caused by Ascaris lumbricoides, Trichuris
trichiura, and hookworms, are among the most common intestinal parasites that infect
humans. The infections are widely distributed throughout tropical and subtropical countries,
including Malaysia, particularly in underprivileged communities. Microscopic and culture
techniques have been used as a gold standard for diagnostic techniques. However, these
methods yield low sensitivity and specificity, laborious and time-consuming. Therefore,
simple, rapid, and accurate alternative methods are needed for the simultaneous detection
of STH infections. Although advanced technologies such as real-time multiplex PCR have
been established, the use of this technique as a routine diagnostic is limited due to the
high cost of the instrument. Therefore, a single-round multiplex conventional PCR assay for
rapid detection of four STH species in the fecal sample was developed in this study. To
perform the single-round multiplex PCR, each pair of species-specific primers was selected
from target genes, including Ancylostoma duodenale (Internal Transcribed Spacer 2; accession
No. AJ001594; 156 base pair), Necator americanus (ITS 2; accession No. AJ001599; 225 base pair),
Ascaris lumbricoides (Internal Transcribed Spacer 1; accession No. AJ000895; 334 base pair)
and Trichuris triciura (partial ITS 1, 5.8s rRNA and partial ITS 2; accession No. AM992981; 518
base pair). The results showed that the newly designed primers could detect the DNA of STH
at low concentrations (0.001 ng/μl) with no cross-amplification with other species. This
assay enables the differentiation of single infections as well as mixed infections. It could
be used as an alternative and is a convenient method for the detection of STHs, especially
for the differentiation of N. americanus and A. duodenale.
5.Survival of antibiotic resistant Escherichia coli in vacuum-packed keropok lekor: Food safety alert among SME keropok lekor producers
Wan-Hamat, H. ; Lani, M.N. ; Hamzah, Y. ; Alias, R. ; Hassan, Z. ; Mahat, N.A.
Tropical Biomedicine 2020;37(No.1):103-115
The microbiological quality of thirty ready-to-eat (RTE) keropok lekor (a sausage shape Malaysian fish product) was evaluated in comparison to microbiological guidelines for ready to eat foods. The two E. coli isolates were subjected to DNA sequencing, identified and tested for their resistance towards fifteen different antibiotics. The survival and growth of the isolated E. coli strains inoculated in keropok lekor at atmospheric air and vacuum packaging were also evaluated. Results revealed that four samples (13.33%) contained Enterobacteriaceae counts that exceeded the recommended allowable counts of 4.0 log10 CFU/g. Unsatisfactory level of coliforms (> 1.7 log10 CFU/g) was also observed in ten of the samples; two of which contained E. coli (2.1 ± 0.17 and 3.7 ± 0.02 log10 CFU/g), suggesting of poor hygiene and sanitation practices. While the ‘Possible E10’ E. coli strain was observably resistant towards Nalidixic acid (30µg) alone, B10 E. coli isolate was worryingly resistant towards Ampicillin (10µg), Ceftazidime (30µg), Ciprofloxacin (5µg), Ceftriaxone (30µg), Nalidixic acid (30µg) and Tetracycline (30µg). This study also revealed that the growth and survival of the ‘Possible E10’ and B10 E. coli strains were not significantly affected by vacuum packaging when stored at both 4°C and 28°C. Therefore, intervention programmes to alert and educate smallmedium enterprisers (SMEs) of keropok lekor producers on food safety as well as potential health risks that can be associated due to inappropriate handling procedures of such product, merits consideration.