1.Violet-pigmented Burkholderia contaminans sequence type 922 bacteremia in an end-stage renal disease patient – a case report and review of the literature
Ahmad S. ; Mohd Sukhaimi N.A. ; Shahimi S.S. ; Mahfodz N.H. ; Soh Y.H. ; AbuBakar S. ; Choong K.Y. ; Loong S.K.
Tropical Biomedicine 2026;43(No. 1):1-4
Burkholderia cepacia complex (Bcc) is an emerging nosocomial pathogen, with violet-pigmented
strains representing a rare and possibly neglected but clinically important subset. We report a case
of a 62-year-old man with end-stage renal disease on dialysis who presented with fever and cough.
Blood cultures from central and peripheral lines grew violet-pigmented, non-lactose fermenting
colonies on MacConkey agar, later identified as Burkholderia contaminans sequence type 922 (ST922)
via a multimodal approach. Initial phenotypic methods (VITEK-2, API20NE and MALDI-ToF) and 16S
rDNA sequencing were inconclusive; however, multilocus sequence typing confirmed ST922, a strain
previously reported in India and associated with nosocomial outbreaks. The isolate was susceptible to
ceftazidime, trimethoprim/sulfamethoxazole, minocycline, and meropenem. The patient responded
well to intravenous ceftazidime, with subsequent blood cultures yielding no growth. Notably,
antimicrobial susceptibility varied geographically, with some ST922 isolates resistant to third-generation
cephalosporins. This case illustrates the diagnostic challenges in Bcc speciation and highlights the value
of molecular tools such as MLST. The detection of this strain in Malaysia raises concerns about global
dissemination, potentially via contaminated medical devices or water systems. Early recognition of
violet-pigmented Bcc in resource-limited settings can facilitate prompt, targeted treatment. This report
underscores the need for environmental surveillance and antimicrobial stewardship to prevent spread,
while reinforcing Bcc’s ecological adaptability and clinical significance, especially in immunocompromised
individuals.
2.Sunlight exposure might account for the relatively low COVID-19 morbidity and mortality in tropical countries
Muhammad, M. ; Loong, S.K. ; Khor, C.S. ; Mohd-Azami, S.N.I. ; Kafle, A. ; Useh, U. ; Bello, B. ; AbuBakar, S.
Tropical Biomedicine 2024;41(No.1):78-83
The present study aimed at exploring whether sunlight exposure might account for the relative
difference in COVID-19-related morbidity and mortality between tropical and non-tropical countries.
A retrospective observational study was designed and data from the World Health Organization
weekly COVID-19 epidemiological update was compiled. We examined the total number of confirmed
COVID-19 cases per 100 000 population, as well as the total number of COVID-19-related mortalities
per 100 000 population. Solar variables data were obtained from the Global Solar Atlas website
(https://globalsolaratlas.info/). These data were analyzed to determine the association of sunlight
exposure to COVID-19-related morbidity and mortality in tropical and non-tropical countries. Results
revealed a statistically significant decrease in the number of confirmed COVID-19 cases per 100 000
population (P<0.001), as well as the number of COVID-19-related mortalities per 100 000 population
(P<0.001) between tropical and non-tropical countries. Analyses of sunlight exposure data found that
specific photovoltaic power output, global horizontal irradiation, diffuse horizontal irradiation and
global tilted irradiation at optimum angle were significantly inversely correlated to COVID-19-related
morbidity and mortality. This suggests that stronger sunlight exposure potentially leads to lower
COVID-19-related morbidity and mortality. Findings from this study suggest that the relatively low
COVID-19-related morbidity and mortality in tropical countries were possibly due to better sunlight
exposure that translates into adequate vitamin D status.
3.Culturable pathogenic bacteria in ticks parasitizing farm animals and rodents in Malaysia
Loong, S.K. ; Lim, F.S. ; Khoo, J.J. ; Lee, H.Y. ; Suntharalingam, C. ; Ishak, S.N. ; Mohd-Taib, F.S. ; AbuBakar, S.
Tropical Biomedicine 2020;37(No.3):803-811
Ticks are vectors of bacteria, protozoa and viruses capable of causing serious and life threatening diseases in humans and animals. Disease transmission occurs through the transfer of pathogen from tick bites to susceptible humans or animals. Most commonly known tick-borne pathogens are obligate intracellular microorganisms but little is known on the prevalence of culturable pathogenic bacteria from ticks capable of growth on artificial nutrient media. One hundred and forty seven ticks originating from dairy cattle, goats and rodents were collected from nine selected sites in Peninsular Malaysia. The culture of surfacesterilized tick homogenates revealed the isolation of various pathogenic bacteria including, Staphylococcus sp., Corynebacterium sp., Rothia sp., Enterococcus faecalis, Klebsiella pneumoniae, Escherichia coli and Bacillus sp. and its derived genera. These pathogens are among those that affect humans and animals. Findings from this study suggest that in addition to the regular intracellular pathogens, ticks could also harbor extracellular pathogenic bacteria. Further studies, hence, would be needed to determine if these extracellular pathogens could contribute to human or animal infection.
4.A Report of Vancomycin-susceptible, Teicoplanin-resistant Enterococcus faecalis ST6 in Malaysia
Loong, S.K. ; Che Mat Seri, N.A.A. ; Mahfodz, N.H. ; Akbar, S.Z. ; AbuBakar, S.
Tropical Biomedicine 2016;33(3):577-582
The ability to acquire antibiotic resistance and virulence has propelled Enterococcus
faecalis to become a major nosocomial pathogen. In Malaysia, data on the antibiotic resistance
determinants and virulence of Enterococcus circulating strains are still scarce. This study
aimed to assess the genotype of an E. faecalis isolate initially identified as Streptococcus
uberis, examine the antibiotic resistance genotypes, analyze the genetic variations within
Tn1546 and investigate the presence of virulence genes. The E. faecalis isolate was genetically
characterized using multilocus sequence typing (MLST). Minimum inhibitory concentrations
to vancomycin and teicoplanin were determined. Antibiotic resistance and other virulence
genes were amplified using nucleic acid polymerase chain reaction. Mapping of the Tn1546
transposon was performed and compared to the prototype sequences. The E. faecalis isolate
was found to have a MLST profile corresponding to sequence type 6. The isolate was resistant
to teicoplanin but susceptible to vancomycin. Its genome consisted the vanA and vanC1
genes. Novel genetic variations in the vanS, vanS-vanH intergenic region and vanY genes
were present and six virulence genes were detected. The detection of the vanC1 gene,
thought to be non-transferable, suggests the potential emergence of inter-species enterococcal
vanC1 gene transfer. The peculiar antibiotics resistance phenotype of this E. faecalis isolate
could be associated to the novel genetic variations found. This study highlights the presence
of E. faecalis belonging to the high-risk clonal complex with multiple virulence factors in
Malaysia.
5.Isolation and Identification of an Emerging Pathogen, Kocuria marina, from Rattus rattus diardii
Loong, S.K. ; Johari, J. ; Che Mat Seri, N.A.A. ; AbuBakar, S.
Tropical Biomedicine 2016;33(3):589-593
Members of the genus Kocuria are commonly found in the environment and they
are also commensals of the mammalian skin and oropharynx mucosa. Human infections,
although rare, are increasingly being reported recently suggesting that this genus has mostly
been overlooked or misidentified. Its transmission route however, is still not known. We
report here the isolation and identification of a Kocuria marina isolate from the lung of a
wild urban rat (Rattus rattus diardii) caught at a wet market. The isolate was susceptible to
most of the commonly used antibiotics. The finding suggests a possibility that rats could be
a vector for K. marina.
6.Emergence of Enterococcus gallinarum carrying vanA gene cluster displaying atypical phenotypes
Loong, S.K. ; Che Mat Seri, N.A.A. ; Mahfodz, N.H. ; Teoh, B.T. ; AbuBakar, S.
Tropical Biomedicine 2016;33(4):837-841
Motile enterococci such as Enterococcus gallinarum has the ability to acquire
and transfer antibiotic resistance genes to other enterococci. Even though infections caused
by E. gallinarum are rare, the discovery of this bacteria in food sources and in clinical
environments is disturbing. Here, we report the isolation and identification of E. gallinarum
from the wound of a hospital in-patient. The isolate was identified using 16S rDNA sequencing.
Isolate 146 harboured the vanA and vanC1 gene clusters, was vancomycin-susceptible, and
displayed resistance to ampicillin, penicillin, erythromycin and teicoplanin. This isolate also
showed intermediate resistance to linezolid and sequencing of the 23S rRNA peptidyl
transferase region did not unveil any known mutations associated to the conferment of
linezolid resistance. The presence of vanA did not confer resistance to vancomycin. Structural
analyses into the Tn1546 transposon carrying the vanA gene revealed distinct genetic variations
in the vanS, vanY and vanS-vanH intergenic region that could be associated to the atypical
antibiotic resistance phenotypes of isolate 146. Finding from this study are suggestive of the
occurrence of interspecies horizontal gene transfer and that similarities in genotypic
characteristic may not necessarily correlate with actual antibiotic resistance pattern of E.
gallinarum.


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