Displaying publications 81 - 100 of 132 in total

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  1. Lee WS, Puthucheary SD
    Med J Malaysia, 2002 Mar;57(1):24-30.
    PMID: 14569714
    A retrospective review of all stool samples obtained from children aged < 16 years with diarrhoea from University of Malaya Medical Centre (UMMC), Kuala Lumpur, from 1978 to 1997 was undertaken to ascertain the pattern of bacterial pathogens causing diarrhoea in children in an urban area in Malaysia. Of 26444 stool samples processed, 2989 (11%) were positive. The five most common bacterial pathogens isolated were non-typhoidal Salmonella (57%), enteropathogenic E. coli (EPEC) (14%), Shigella spp. (11%), Campylobacter spp. (5%) and Aeromonas spp. (4%). There was a significant reduction in the average percentage of positive isolation during the last 5 years of the study period as compared to the first 5 years (15.0% vs. 7.2%; r = -0.92, p = 0.0001). EPEC and Shigella spp. were less commonly isolated in the last five years compared with the first five years of the study (6% vs 21% p < 0.001 for E. coli; 7% vs 22%, p < 0.001 for Shigella spp.). This information is important for public health education in reducing the incidence of childhood diarrhoea further, and in the selection of appropriate antimicrobials in the management of extra-intestinal complications of childhood diarrhoea.
  2. Lee WS, Puthucheary SD, Parasakthi N, Choo KE
    J Trop Pediatr, 2003 Feb;49(1):37-41.
    PMID: 12630719
    There is widespread resistance of Salmonella species to commonly prescribed antimicrobials the world over. We aimed to determine the antimicrobial susceptibility and serovar distribution of non-typhoidal Salmonella (NTS) isolated from blood cultures of Malaysian children. Positive isolates of NTS from blood cultures obtained from children admitted to the pediatric wards of University of Malaya Medical Center (UMMC), a large urban hospital from Kuala Lumpur (1991-2001), and Hospital Kota Bharu (HKB), from the predominantly rural state of Kelantan (1991-1999), Malaysia, were reviewed retrospectively. Serovar distribution and antimicrobial susceptibility were ascertained. A total of 64 and 55 isolates of NTS were obtained from blood cultures of children admitted to UMMC and HKB, respectively. The commonest serovar isolated was Salmonella enteritidis in both centers. The NTS isolated were highly sensitive to the antimicrobials tested: ampicillin 98 per cent, chloramphenicol 98 per cent, gentamicin 97 per cent, trimethoprim-sulfamethoxazole (TMP-SMX) 98 per cent, and ceftriaxone 100 per cent in UMMC; ampicillin 100 per cent, chloramphenicol 87 per cent, kanamycin 100 per cent, streptomycin 96 per cent, TMP-SMX 93 per cent, and tetracycline 89 per cent in HKB. There were only one and five multi-resistant isolates in UMMC and HKB, respectively. In conclusion, NTS isolated from blood cultures of Malaysian children from Kuala Lumpur and Kota Bharu were highly sensitive to commonly prescribed antibiotics. We speculate that this is due to the restriction of sales of antimicrobials in Malaysia except by prescription. Continuing vigilance and frequent antmicrobial surveillance is necessary.
  3. Lee WS, Puthucheary SD, Parasakthi N
    Ann Trop Paediatr, 2000 Jun;20(2):125-9.
    PMID: 10945063
    Extra-intestinal non-typhoidal Salmonella (NTS) infections are uncommon in developed countries but common in developing ones. The risk factors, clinical features and outcome of children admitted to the Department of Paediatrics, University of Malaya Medical Center, Kuala Lumpur from 1978 to 1998 with extra-intestinal NTS infections were reviewed. All positive cultures of NTS, blood, cerebrospinal fluid, urine, synovial, pericardial and other body secretions (except stools), were included. Of the 98 cases reviewed, 56 were boys and 42 girls. The mean age was 2.1 years (range: newborn to 14 years). Twenty-seven children were severely immunocompromised and 21 had underlying chronic medical disorders. Bacteraemia was the most commonly detected type of infection and meningitis the commonest focal infection. The overall mortality rate was 15%. An immunocompromised state or underlying chronic medical disorder was associated with increased mortality. The three serotypes most commonly isolated were S. enteritidis, S. paratyphi B and S. typhimurium. Most isolates were sensitive to antibiotics commonly used in salmonellosis.
  4. Lee WS, Puthucheary SD, Omar A
    J Paediatr Child Health, 1999 Aug;35(4):379-82.
    PMID: 10457297
    OBJECTIVE: To review the presenting features, complications and outcome of infants with Salmonella meningitis.

    METHODOLOGY: Retrospective review of all cultures of cerebrospinal fluid positive for bacteria in children below 12 years of age, processed at the Department of Medical Microbiology, University of Malaya Medical Centre, Kuala Lumpur from 1973 to 1997. Records of all cases positive for Salmonella species were retrieved and studied.

    RESULTS: Thirteen infants aged 3 days to 9 months with Salmonella meningitis were included. The median age of onset of symptoms was 4 months. The clinical and laboratory features were similar to other causes of bacterial meningitis. Salmonella enteritidis was the commonest serotype isolated. Nine infants developed fits, six of which were difficult to control. Other complications noted were hydrocephalus (five), subdural effusions (four), empyema (three), ventriculitis (two), intracranial haemorrhage and cerebral abscess (one each). The use of ampicillin and/or chloramphenicol and inadequate duration of therapy resulted in recrudescence or relapse in five infants. The overall mortality was 18%. The presence of empyema, intracerebral abscess, ventriculitis, hydrocephalus, and intracranial haemorrhage were associated with adverse neurodevelopmental sequelae or death. More than half of those who survived had normal long-term outcome.

    CONCLUSION: Infants who developed neurological complications as a result of Salmonella meningitis had significant mortality and adverse long-term neurodevelopment outcome.

  5. Lee WS, Puthucheary SD, Boey CC
    J Paediatr Child Health, 1998 Aug;34(4):387-90.
    PMID: 9727185
    OBJECTIVE: To study the clinical features of non-typhoid Salmonella gastroenteritis and the incidence, risk factors and outcome of invasive complications in urban Malaysian children. To describe the serotypes of Salmonella species isolated and the pattern of antibiotic susceptibility.

    METHODOLOGY: Retrospective review of a group of 131 children with non-typhoid Salmonella gastroenteritis seen at the University Hospital, Kuala Lumpur, Malaysia from January 1994 to December 1996.

    RESULTS: Sixty-seven percent were infants below one year of age. Fever and vomiting were seen in nearly half of children. Seven children (5.3%) had invasive complications: 5 bacteraemia and 2 meningitis. Age below 6 months, fever > 38.0 degrees C, and dehydration on admission were significantly associated with invasive complications. The commonest serotypes isolated were S. enteritidis, S. paratyphi B, and S. bovis-morbificans. A total of 94-100% of isolates were susceptible to commonly prescribed antibiotics.

    CONCLUSIONS: Children with Salmonella gastroenteritis below 6 months of age who are febrile and dehydrated should be treated empirically with antibiotics until the result of blood culture is available.

  6. Lee WS, Puthucheary SD
    Med J Malaysia, 2003 Jun;58(2):262-7.
    PMID: 14569747 MyJurnal
    There is an increasing trend for Shigella isolates worldwide to be resistant to commonly prescribed antibiotics. The species distribution and antibiotic resistance of Shigella species isolated from children in Kuala Lumpur, Malaysia from 1978 to 1997 was reviewed. Three hundred and eighty six isolates were positive for Shigella species, representing 1.4% (95% CI: 1.3%-1.6%) of the 26320 total stool specimens and 13% (95% CI: 11.8%-14.2%) of 2986 isolates positive for bacterial pathogens. Shigella flexneri, constituting 74% of all isolates in the first five years of the study, decreased by 40% during the last five years (95% CI of decrease: 22.1%-57.9%), p-value < 0.0001) to 34%. There was a significant reduction (chi2 for linear trend = 77.6, p-value < 0.001) in the number of Shigella isolates as a percentage of total stool isolates obtained. 58% of the 241 isolates tested for antibiotic sensitivity were resistant to at least one antibiotic, and 42% wEre multi-resistant to three or more antibiotics. Shigella species was not a common pathogen among children admitted with diarrhoea in Kuala Lumpur, and was more likely to be resistant to commonly prescribed antibiotics.
  7. Lee WS, Puthucheary SD
    Singapore Med J, 2001 Feb;42(2):057-60.
    PMID: 11358191
    To describe the patterns of isolation of Aeromonas spp. and the resulting spectrum of infection, intestinal and extra-intestinal,from infants and children in an urban area in a hot and humid country from SoutheastAsia.
  8. Lee EI, Khoo BH, Puthucheary SD, Thong ML
    Med J Malaysia, 1977 Dec;32(2):114-9.
    PMID: 26858
  9. Lau TV, Puah SM, Tan JMA, Puthucheary SD, Chua KH
    Braz J Microbiol, 2021 Jun;52(2):517-529.
    PMID: 33768508 DOI: 10.1007/s42770-021-00457-8
    Flagellar-mediated motility is a crucial virulence factor in many bacterial species. A dual flagellar system has been described in aeromonads; however, there is no flagella-related study in the emergent human pathogen Aeromonas dhakensis. Using 46 clinical A. dhakensis, phenotypic motility, genotypic characteristics (flagellar genes and sequence types), biochemical properties and their relationship were investigated in this study. All 46 strains showed swimming motility at 30 °C in 0.3% Bacto agar and carried the most prevalent 6 polar flagellar genes cheA, flgE, flgG, flgH, flgL, and flgN. On the contrary, only 18 strains (39%) demonstrated swarming motility on 0.5% Eiken agar at 30 °C and they harbored 11 lateral flagellar genes lafB, lafK, lafS, lafT, lafU, flgCL, flgGL, flgNL, fliEL, fliFL, and fliGL. No association was found between biochemical properties and motility phenotypes. Interestingly, a significant association between swarming and strains isolated from pus was observed (p = 0.0171). Three strains 187, 277, and 289 isolated from pus belonged to novel sequence types (ST522 and ST524) exhibited fast swimming and swarming profiles, and they harbored > 90% of the flagellar genes tested. Our findings provide a fundamental understanding of flagellar-mediated motility in A. dhakensis.
  10. Lau TV, Puah SM, Tan JMA, Merino S, Puthucheary SD, Chua KH
    Microb Pathog, 2023 Apr;177:106059.
    PMID: 36878334 DOI: 10.1016/j.micpath.2023.106059
    Aeromonas dhakensis possesses dual flagellar systems for motility under different environments. Flagella-mediated motility is necessary for biofilm formation through an initial attachment of bacteria to the surface, but this has not been elucidated in A. dhakensis. This study investigates the role of polar (flaH, maf1) and lateral (lafB, lafK and lafS) flagellar genes in the biofilm formation of a clinical A. dhakensis strain WT187 isolated from burn wound infection. Five deletion mutants and corresponding complemented strains were constructed using pDM4 and pBAD33 vectors, respectively, and analyzed for motility and biofilm formation using crystal violet staining and real-time impedance-based assays. All mutants were significantly reduced in swimming (p 
  11. Lau TTV, Tan JMA, Puthucheary SD, Puah SM, Chua KH
    Braz J Microbiol, 2020 Sep;51(3):909-918.
    PMID: 32067209 DOI: 10.1007/s42770-020-00239-8
    Aeromonas dhakensis is an emergent human pathogen with medical importance. This study was aimed to determine the sequence types (STs), genetic diversity, and phylogenetic relationships of different clinical sources of 47 A. dhakensis from Malaysia using multilocus sequence typing (MLST), goeBURST, and phylogenetic analyses. The analysis of a concatenated six-gene tree with a nucleotide length of 2994 bp based on six housekeeping genes (gyrB, groL, gltA, metG, ppsA, and recA) and independent analyses of single gene fragments was performed. MLST was able to group 47 A. dhakensis from our collection into 36 STs in which 34 STs are novel STs. The most abundant ST521 consisted of five strains from peritoneal fluid and two strains from stools. Comparison of 62 global A. dhakensis was carried out via goeBURST; 94.4% (34/36) of the identified STs are novel and unique in Malaysia. Two STs (111 and 541) were grouped into clonal complexes among our strains and 32 STs occurred as singletons. Single-gene phylogenetic trees showed varying topologies; groL and rpoD grouped all A. dhakensis into a tight-cluster with bootstrap values of 100% and 99%, respectively. A poor phylogenetic resolution encountered in single-gene analyses was buffered by the multilocus phylogenetic tree that offered high discriminatory power (bootstrap value = 100%) in resolving all A. dhakensis from A. hydrophila and delineating the relationship among other taxa. Genetic diversity analysis showed groL as the most conserved gene and ppsA as the most variable gene. This study revealed novel STs and high genetic diversity among clinical A. dhakensis from Malaysia.
  12. Kwan PW, Khoo BH, Lam KL, Puthucheary SD
    Med J Malaysia, 1979 Sep;34(1):71-5.
    PMID: 396463
  13. Koh SF, Tay ST, Sermswan R, Wongratanacheewin S, Chua KH, Puthucheary SD
    J Microbiol Methods, 2012 Sep;90(3):305-8.
    PMID: 22705921 DOI: 10.1016/j.mimet.2012.06.002
    We have developed a multiplex PCR assay for rapid identification and differentiation of cultures for Burkholderia pseudomallei, Burkholderia thailandensis, Burkholderia mallei and Burkholderia cepacia complex. The assay is valuable for use in clinical and veterinary laboratories, and in a deployable laboratory during outbreaks.
  14. Koh SF, Tay ST, Puthucheary SD
    Trop Biomed, 2013 Sep;30(3):428-33.
    PMID: 24189672 MyJurnal
    Burkholderia pseudomallei the causative agent of melioidosis, is being increasingly recognized as an important cause of morbidity and mortality in South East Asia. Biofilm formation of B. pseudomallei may be responsible for dormancy, latency and relapse of melioidosis. Based on the colonial morphology of the bacteria on B. pseudomallei selective agar medium, seven distinct morphotypes were identified. This study was conducted to assess the in vitro biofilm produced by B. pseudomallei and to investigate possible correlation between B. pseudomallei morphotypes with biofilm forming abilities of the isolates. Using a standard biofilm crystal violet staining assay, comparison was made between the biofilm forming ability of 76 isolates of B. pseudomallei and Burkholderia thailandensis ATCC 700388. Amongst the blood isolates, 30.2% were considered as high biofilm producers and 27.9% were low producers, 33.3% of the pus isolates were considered as high and 16% low biofilm producers. Most of the isolates were identified as morphotype group 1 which displayed a rough centre with irregular circumference on the agar medium. However, we did not find any correlation of B. pseudomallei morphotypes with biofilm forming abilities (p > 0.05). Additional studies are needed to identify internal and external factors which contribute to the high and low biofilm formation of B. pseudomallei.
  15. Khor WC, Puah SM, Tan JA, Puthucheary SD, Chua KH
    PLoS One, 2015;10(12):e0145933.
    PMID: 26710336 DOI: 10.1371/journal.pone.0145933
    Gram-negative bacilli of the genus Aeromonas are primarily inhabitants of the aquatic environment. Humans acquire this organism from a wide range of food and water sources as well as during aquatic recreational activities. In the present study, the diversity and distribution of Aeromonas species from freshwater lakes in Malaysia was investigated using glycerophospholipid-cholesterol acyltransferase (GCAT) and RNA polymerase sigma-factor (rpoD) genes for speciation. A total of 122 possible Aeromonas strains were isolated and confirmed to genus level using the API20E system. The clonality of the isolates was investigated using ERIC-PCR and 20 duplicate isolates were excluded from the study. The specific GCAT-PCR identified all isolates as belonging to the genus Aeromonas, in agreement with the biochemical identification. A phylogenetic tree was constructed using the rpoD gene sequence and all 102 isolates were identified as: A. veronii 43%, A. jandaei 37%, A. hydrophila 6%, A. caviae 4%, A. salmonicida 2%, A. media 2%, A. allosaccharophila 1%, A. dhakensis 1% and Aeromonas spp. 4%. Twelve virulence genes were present in the following proportions--exu 96%, ser 93%, aer 87%, fla 83%, enolase 70%, ela 62%, act 54%, aexT 33%, lip 16%, dam 16%, alt 8% and ast 4%, and at least 2 of these genes were present in all 102 strains. The ascV, aexU and hlyA genes were not detected among the isolates. A. hydrophila was the main species containing virulence genes alt and ast either present alone or in combination. It is possible that different mechanisms may be used by each genospecies to demonstrate virulence. In summary, with the use of GCAT and rpoD genes, unambiguous identification of Aeromonas species is possible and provides valuable data on the phylogenetic diversity of the organism.
  16. Khor WC, Puah SM, Koh TH, Tan JAMA, Puthucheary SD, Chua KH
    Microb Drug Resist, 2018 May;24(4):469-478.
    PMID: 29461928 DOI: 10.1089/mdr.2017.0083
    OBJECTIVE: The objective of this study was to examine the species distribution, genetic relatedness, virulence gene profiles, antimicrobial sensitivities, and resistance gene distribution of clinical Aeromonas strains from Singapore and Malaysia.

    METHODS: A total of 210 Aeromonas clinical isolates were investigated: 116 from Singapore General Hospital and 94 archived clinical isolates from University of Malaya Medical Center, Malaysia. The isolates were genetically identified based on the gcat gene screening and the partial sequences of the rpoD housekeeping gene. Genetic relatedness, distribution of 15 virulence genes and 4 beta-lactamase resistance genes, and susceptibility patterns to 11 antimicrobial agents were compared.

    RESULTS: Of the 210 Aeromonas isolates, A. dhakensis-94 (45%) was the dominant species in Singapore and Malaysia. Species composition was similar and enterobacterial repetitive intergenic consensus-PCR did not show genetic relatedness between strains from the two countries. Of the 15 virulence genes, A. dhakensis and A. hydrophila harbored the most compared with other species. Different combinations of 9 virulence genes (exu, fla, lip, eno, alt, dam, hlyA, aexU, and ascV) were present in A. dhakensis, A. hydrophila, and A. veronii from both the countries. Distribution of virulence genes was species and anatomic site related. Majority (>80%) of the strains were susceptible to all antimicrobial agents tested, except amoxicillin and cephalothin. A. dhakensis strains from Malaysia significantly harbored the cphA gene compared with A. dhakensis from Singapore. Multidrug resistance was mostly detected in strains from peritoneal fluids of dialysis patients.

    CONCLUSION: This study revealed A. dhakensis as the dominant species isolated in both geographic regions, and that it carried a high number of virulence genes. It also highlights the geographic-related differences of virulence gene distribution and antimicrobial resistance profiles of clinical Aeromonas strains from Singapore and Malaysia.

  17. Karunakaran R, Puthucheary SD
    Scand. J. Infect. Dis., 2007;39(10):858-61.
    PMID: 17852912
    The treatment of melioidosis currently involves the use of antimicrobials such as ceftazidime, trimethoprim-sulfamethoxazole, amoxicillin-clavulanate and doxycycline. Evaluation of other antimicrobials with activity against the organism continues to be pursued, however, as the causative organism, B. pseudomallei, may not always be susceptible to the above antimicrobials. This study aimed to test the susceptibility of Malaysian isolates of B. pseudomallei against imipenem, meropenem, ertapenem, moxifloxacin and azithromycin. 80 previously stocked clinical isolates collected between 1978 and 2003 from the UMMC, Kuala Lumpur were tested for in vitro susceptibility to these antimicrobials using the E-test minimum inhibitory concentration method. 100% of isolates were sensitive to imipenem and meropenem, 97.5% were sensitive to trimethoprim-sulfamethozaxole, 37.5% to moxifloxacin, and only a minority was sensitive to ertapenem (7.5%). Using breakpoints for Staphylococcus and Haemophilus, 5.0%-6.3% of isolates were sensitive to azithromycin. In conclusion, our findings support the in vitro efficacy of imipenem, meropenem and trimethoprim-sulfamethoxazole against B. pseudomallei. Moxifloxacin, ertapenem and azithromycin cannot be recommended for the treatment of melioidosis; however, further studies are needed to test the efficacy of azithromycin in combination with quinolones.
  18. Karunakaran R, Marret MJ, Hassan H, Puthucheary SD
    Malays J Pathol, 2004 Jun;26(1):49-52.
    PMID: 16190107
    A 2-year-old boy with underlying congenital cyanotic heart disease presented with seizures and fever and was found to have bilateral parietal cerebral abscesses. Drainage of the pus from the abscesses was done in stages; on the day of admission, four days after admission and 3 weeks after admission. Although the pus from the first drainage did not grow any organisms, the pus from the second drainage on the fourth day of admission yielded a mixed growth of Eikenella corrodens and Streptococcus milleri. Following the second drainage of pus, the child was noted to have mild weakness (grade 3/5) and increased tone in the left upper limb. Three weeks after admission, due to recurring fever, further neurological signs and findings of an enlarging right cerebral abscess on a repeat CT scan, a third drainage was carried out. However no growth was obtained from this specimen. This patient was managed both surgically and with appropriate antibiotics. Over the next four months, serial CT scans revealed gradual resolution of the abscesses with disappearance of the surrounding oedema. The child showed gradual recovery of his left sided weakness with resolution of tone and reflexes to normal.
  19. Karunakaran R, Tay ST, Rahim FF, Lim BB, Sam IC, Kahar-Bador M, et al.
    Jpn J Infect Dis, 2012;65(5):433-5.
    PMID: 22996219
    The prevalence of ceftriaxone resistance and the associated genes encoding extended-spectrum β-lactamase (ESBL) was determined in 149 non-duplicate non-typhoidal Salmonella isolated in 2008-2009 from patients in a tertiary care hospital in Kuala Lumpur, Malaysia. The resistance rate to ceftriaxone was 2.7% (2/74) in 2008, 4.0% (3/75) in 2009, and 3.4% (5/149) overall. CTX-M ESBL genes were detected in 2 of the 5 ceftriaxone-resistant isolates. The prevalence of ceftriaxone resistance, although low, is a concern because it limits therapeutic options. Continued surveillance of ceftriaxone resistance is important to monitor its trends.
  20. Karunakaran R, Tay ST, Rahim FF, Lim BB, Puthucheary SD
    Jpn J Infect Dis, 2014;67(3):157-62.
    PMID: 24858603
    We investigated the prevalence of non-typhoidal Salmonella (NTS) with "reduced susceptibility to ciprofloxacin" (RS-Cip) (minimum inhibitory concentration [MIC], 0.12-1.0 μg/mL) as well as their resistance genes in 75 NTS isolates (53 from stool, 21 from blood, and 1 from urine) from patients at a tertiary care Malaysian hospital between January and December 2009. RS-Cip was detected in 24/75 (32.0%) isolates. Using the ciprofloxacin MIC interpretive criteria for Salmonella in the Clinical and Laboratory Standards Institute 2013 guidelines, 51/75 (68.0%) isolates were found to be sensitive, 22/75 (29.3%) were intermediate, and 2/75 (2.7%) were resistant to ciprofloxacin. The 24 isolates that were intermediate or resistant to ciprofloxacin were the same isolates categorized as having RS-Cip. Among the 23 tested isolates with RS-Cip, the qnrS gene was detected in 17/23 (73.9%) and single gyrA mutations were detected in 6/23 (26.1%) (Asp87Tyr [n = 3], Asp87Asn [n = 2], and Ser83Phe [n = 1]). A parC (Thr57Ser) mutation was detected in 13/23 (56.5%) isolates, coexisting with either a qnrS gene or a gyrA mutation. The high incidence of the qnrS gene among isolates with RS-Cip needs to be monitored because qnr genes can spread via plasmids and aid in the emergence of increased resistance levels.
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