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  1. Fulltext Corrigendum: The Microbiome and Irritable Bowel Syndrome - A Review on the Pathophysiology, Current Research and Future Therapy
    Chong PP, Chin VK, Looi CY, Wong WF, Madhavan P, Yong VC
    Front Microbiol, 2019 08 13;10:1870.
    PMID: 31456783 DOI: 10.3389/fmicb.2019.01870
    [This corrects the article DOI: 10.3389/fmicb.2019.01136.].
  2. Fulltext The Microbiome and Irritable Bowel Syndrome - A Review on the Pathophysiology, Current Research and Future Therapy
    Chong PP, Chin VK, Looi CY, Wong WF, Madhavan P, Yong VC
    Front Microbiol, 2019;10:1136.
    PMID: 31244784 DOI: 10.3389/fmicb.2019.01136
    Irritable bowel syndrome (IBS) is a functional disorder which affects a large proportion of the population globally. The precise etiology of IBS is still unknown, although consensus understanding proposes IBS to be of multifactorial origin with yet undefined subtypes. Genetic and epigenetic factors, stress-related nervous and endocrine systems, immune dysregulation and the brain-gut axis seem to be contributing factors that predispose individuals to IBS. In addition to food hypersensitivity, toxins and adverse life events, chronic infections and dysbiotic gut microbiota have been suggested to trigger IBS symptoms in tandem with the predisposing factors. This review will summarize the pathophysiology of IBS and the role of gut microbiota in relation to IBS. Current methodologies for microbiome studies in IBS such as genome sequencing, metagenomics, culturomics and animal models will be discussed. The myriad of therapy options such as immunoglobulins (immune-based therapy), probiotics and prebiotics, dietary modifications including FODMAP restriction diet and gluten-free diet, as well as fecal transplantation will be reviewed. Finally this review will highlight future directions in IBS therapy research, including identification of new molecular targets, application of 3-D gut model, gut-on-a-chip and personalized therapy.
  3. The role of host microfilaments and microtubules during opsonin-independent interactions of Cryptococcus neoformans with mammalian lung cells
    Choo KK, Chong PP, Ho AS, Yong PV
    Eur J Clin Microbiol Infect Dis, 2015 Dec;34(12):2421-7.
    PMID: 26463450 DOI: 10.1007/s10096-015-2497-4
    The purpose of this investigation was to characterise the interactions of Cryptococcus neoformans with mammalian host alveolar epithelial cells and alveolar macrophages, with emphasis on the roles of the cryptococcal capsule and the host cell cytoskeletons. The adherence and internalisation of C. neoformans into mammalian lung cells and the roles of host cell cytoskeletons in host-pathogen interactions were studied using in vitro models coupled with a differential fluorescence assay, fluorescence staining, immunofluorescence and drug inhibition of actin and microtubule polymerisation. Under conditions devoid of opsonin and macrophage activation, C. neoformans has a high affinity towards MH-S alveolar macrophages, yet associated poorly to A549 alveolar epithelial cells. Acapsular C. neoformans adhered to and internalised into the mammalian cells more effectively compared to encapsulated cryptococci. Acapsular C. neoformans induced prominent actin reorganisation at the host-pathogen interface in MH-S alveolar macrophages, but minimally affected actin reorganisation in A549 alveolar epithelial cells. Acapsular C. neoformans also induced localisation of microtubules to internalised cryptococci in MH-S cells. Drug inhibition of actin and microtubule polymerisation both reduced the association of acapsular C. neoformans to alveolar macrophages. The current study visualises and confirms the interactions of C. neoformans with mammalian alveolar cells during the establishment of infection in the lungs. The acapsular form of C. neoformans effectively adhered to and internalised into alveolar macrophages by inducing localised actin reorganisation, relying on the host's actin and microtubule activities.
  4. Fulltext Prevalence and viral load of oncogenic human papillomavirus (HPV) in pterygia in multi-ethnic patients in the Malay Peninsula
    Chong PP, Tung CH, Rahman NA, Yajima M, Chin FW, Yeng CL, et al.
    Acta Ophthalmol, 2014 Nov;92(7):e569-79.
    PMID: 25043991 DOI: 10.1111/aos.12427
    The aim of the study was to determine the prevalence of human papillomavirus (HPV) in primary and recurrent pterygia samples collected from different ethnic groups in the equatorial Malay Peninsula.
  5. Fulltext Emergence and molecular mechanisms of SARS-CoV-2 and HIV to target host cells and potential therapeutics
    Saleemi MA, Ahmad B, Benchoula K, Vohra MS, Mea HJ, Chong PP, et al.
    Infect Genet Evol, 2020 11;85:104583.
    PMID: 33035643 DOI: 10.1016/j.meegid.2020.104583
    The emergence of a new coronavirus, in around late December 2019 which had first been reported in Wuhan, China has now developed into a massive threat to global public health. The World Health Organization (WHO) has named the disease caused by the virus as COVID-19 and the virus which is the culprit was renamed from the initial novel respiratory 2019 coronavirus to SARS-CoV-2. The person-to-person transmission of this virus is ongoing despite drastic public health mitigation measures such as social distancing and movement restrictions implemented in most countries. Understanding the source of such an infectious pathogen is crucial to develop a means of avoiding transmission and further to develop therapeutic drugs and vaccines. To identify the etiological source of a novel human pathogen is a dynamic process that needs comprehensive and extensive scientific validations, such as observed in the Middle East respiratory syndrome (MERS), severe acute respiratory syndrome (SARS), and human immunodeficiency virus (HIV) cases. In this context, this review is devoted to understanding the taxonomic characteristics of SARS-CoV-2 and HIV. Herein, we discuss the emergence and molecular mechanisms of both viral infections. Nevertheless, no vaccine or therapeutic drug is yet to be approved for the treatment of SARS-CoV-2, although it is highly likely that new effective medications that target the virus specifically will take years to establish. Therefore, this review reflects the latest repurpose of existing antiviral therapeutic drug choices available to combat SARS-CoV-2.
  6. Fulltext Comparison of nested and ELISA based polymerase chain reaction assays for detecting Chlamydia trachomatis in pregnant women with preterm complications
    Sulaiman S, Chong PP, Mokhtarudin R, Lye MS, Wan Hassan WH
    Trop Biomed, 2014 Mar;31(1):36-45.
    PMID: 24862043 MyJurnal
    Identification of pregnant women infected with Chlamydia trachomatis is essential to allow early antibiotic treatment in order to prevent adverse pregnancy outcomes. In this study, two nucleic acid amplification tests (NAAT) namely nested PCR (BioSewoom, Korea) and Amplicor CT/NG (Roche Diagnostic, USA) were evaluated in terms of sensitivity and specificity for the detection of C. trachomatis DNA in pregnant women with preterm complications. A cross-sectional study was carried out in two public hospitals in Southern Selangor, Malaysia. Endocervical swabs obtained were subjected to DNA amplification using nested PCR (BioSewoom, Korea) and Amplicor CT/NG (Roche Diagnostic, USA). A total of 83 endocervical swabs obtained from pregnant women of less than 37 weeks gestation and presented with preterm complications were subjected to chlamydial DNA detection using both assays. The study shows that Amplicor CT/NG assay is more effective in the detection of C. trachomatis DNA from endocervical swabs compared to Biosewoom nested PCR kit. Agreement between the two assays were poor (kappa=0.094) with nested PCR showing a low sensitivity of 10.81% and a 97.83% specificity when compared to Amplicor CT/NG. The results obtained indicated that BioSewoom nested PCR was less sensitive than Amplicor CT/ NG for detecting C. trachomatis in endocervical specimens and that another more reliable test is required for confirmatory result.
  7. Growth, biofilm formation, antifungal susceptibility and oxidative stress resistance of Candida glabrata are affected by different glucose concentrations
    Ng TS, Desa MNM, Sandai D, Chong PP, Than LTL
    Infect Genet Evol, 2016 06;40:331-338.
    PMID: 26358577 DOI: 10.1016/j.meegid.2015.09.004
    Glucose is an important fuel source to support many living organisms. Its importance in the physiological fitness and pathogenicity of Candida glabrata, an emerging human fungal pathogen has not been extensively studied. The present study aimed to investigate the effects of glucose on the growth, biofilm formation, antifungal susceptibility and oxidative stress resistance of C. glabrata. In addition, its effect on the expression of a putative high affinity glucose sensor gene, SNF3 was also investigated. Glucose concentrations were found to exert effects on the physiological responses of C. glabrata. The growth rate of the species correlated positively to the amount of glucose. In addition, low glucose environments were found to induce C. glabrata to form biofilm and resist amphotericin B. Conversely, high glucose environments promoted oxidative stress resistance of C. glabrata. The expression of CgSNF3 was found to be significantly up-regulated in low glucose environments. The expression of SNF3 gene in clinical isolates was found to be higher compared to ATCC laboratory strains in low glucose concentrations, which may explain the better survivability of clinical isolates in the low glucose environment. These observations demonstrated the impact of glucose in directing the physiology and virulence fitness of C. glabrata through the possible modulation by SNF3 as a glucose sensor, which in turn aids the species to adapt, survive and thrive in hostile host environment.
  8. Fulltext Phylogenetic and Transcripts Profiling of Glucose Sensing Related Genes in Candida glabrata
    Ng TS, Mohd Desa MN, Sandai D, Chong PP, Than LT
    Jundishapur J Microbiol, 2015 Nov;8(11):e25177.
    PMID: 26855740 DOI: 10.5812/jjm.25177
    BACKGROUND: The sensing mechanism of glucose in Saccharomyces cerevisiae is well studied. However, such information is scarcely found in other yeast species such as Candida glabrata.

    OBJECTIVES: This study aimed to identify the glucose sensing pathway related genes of C. glabrata and to analyze the regulation pattern of these genes in response to different surrounding glucose concentrations through the quantitative real time polymerase chain reaction (qRT-PCR).

    MATERIALS AND METHODS: Phylogenetic analysis was carried out on predicted amino acid sequences of C. glabrata and S. cerevisiae to compare their degree of similarity. In addition, the growth of C. glabrata in response to different amounts of glucose (0%, 0.01%, 0.1%, 1% and 2%) was evaluated via the spot dilution assay on prepared agar medium. Besides, the SNF3 and RGT2, which act as putative glucose sensors, and the RGT1 and MIG1, which act as putative transcriptional regulators and selected downstream hexose transporters (HXTs), were analysed through qRT-PCR analysis for the gene expression level under different glucose concentrations.

    RESULTS: Comparative analysis of predicted amino acids in the phylogenetic tree showed high similarity between C. glabrata and S cerevisiae. Besides, C. glabrata demonstrated the capability to grow in glucose levels as low as 0.01% in the spot dilution assay. In qRT-PCR analysis, differential expressions were observed in selected genes when C. glabrata was subjected to different glucose concentrations.

    CONCLUSIONS: The constructed phylogenetic tree suggests the close evolutionary relationship between C. glabrata and S. cerevisiae. The capability of C. glabrata to grow in extremely low glucose environments and the differential expression of selected glucose-sensing related genes suggested the possible role of these genes in modulating the growth of C. glabrata in response to different glucose concentrations. This study helps deepen our understanding of the glucose sensing mechanism in C. glabrata and serves to provide fundamental data that may assist in unveiling this mechanism as a potential drug target.

  9. Fulltext SNF3 as High Affinity Glucose Sensor and Its Function in Supporting the Viability of Candida glabrata under Glucose-Limited Environment
    Ng TS, Chew SY, Rangasamy P, Mohd Desa MN, Sandai D, Chong PP, et al.
    Front Microbiol, 2015;6:1334.
    PMID: 26648919 DOI: 10.3389/fmicb.2015.01334
    Candida glabrata is an emerging human fungal pathogen that has efficacious nutrient sensing and responsiveness ability. It can be seen through its ability to thrive in diverse range of nutrient limited-human anatomical sites. Therefore, nutrient sensing particularly glucose sensing is thought to be crucial in contributing to the development and fitness of the pathogen. This study aimed to elucidate the role of SNF3 (Sucrose Non Fermenting 3) as a glucose sensor and its possible role in contributing to the fitness and survivability of C. glabrata in glucose-limited environment. The SNF3 knockout strain was constructed and subjected to different glucose concentrations to evaluate its growth, biofilm formation, amphotericin B susceptibility, ex vivo survivability and effects on the transcriptional profiling of the sugar receptor repressor (SRR) pathway-related genes. The CgSNF3Δ strain showed a retarded growth in low glucose environments (0.01 and 0.1%) in both fermentation and respiration-preferred conditions but grew well in high glucose concentration environments (1 and 2%). It was also found to be more susceptible to amphotericin B in low glucose environment (0.1%) and macrophage engulfment but showed no difference in the biofilm formation capability. The deletion of SNF3 also resulted in the down-regulation of about half of hexose transporters genes (four out of nine). Overall, the deletion of SNF3 causes significant reduction in the ability of C. glabrata to sense limited surrounding glucose and consequently disrupts its competency to transport and perform the uptake of this critical nutrient. This study highlighted the role of SNF3 as a high affinity glucose sensor and its role in aiding the survivability of C. glabrata particularly in glucose limited environment.
  10. Soy husk extract improves physical and biochemical parameters of obese-diabetic rats through the regulation of PPARγ expression
    Tan ST, Ismail A, Hamid M, Chong PP, Sun J
    J Food Biochem, 2019 05;43(5):e12843.
    PMID: 31353513 DOI: 10.1111/jfbc.12843
    Unhealthy eating habits and lack of physical activities are among the contributing factors for obesity and diabetes. It has been reported that consumption of naturally occurring phenolics could exert beneficial effects toward these diseases. Therefore, this study aims to evaluate the ability of phenolic-rich soy husk powder extract (SHPE) in modifying the physical and biochemical parameters for obesity and diabetes. Forty-nine Sprague Dawley rats were divided into seven groups, including three supplementary/treatment groups. Rats in supplementary/treatment groups were provided with either 4 mg/kg BW Rosiglitazone Maleate, 250 mg SHPE/kg BW, or 500 mg SHPE/kg BW. The effectiveness of SHPE in alleviating obesity-diabetes was evaluated by measuring body weight (physical parameter), blood glucose metabolisms (biochemical parameters), and PPARγ expression. Findings in the present study revealed that short-term SHPE and Rosiglitazone Maleate administration improved the physical and biochemical parameters of obese-diabetic rats. In addition, SHPE was also demonstrated to upregulate PPARγ expression in adipocytes. These findings suggest that soy husk could emerge as a potential hypoglycemic and anti-adipogenic nutraceutical in future. PRACTICAL APPLICATIONS: This was the first study to evaluate the potential effects of soy husk against the parameters of obese-diabetes in rats. In addition, promising effects derived from this study might explore the possibility of soy husk to be utilized as an antidiabetes nutraceutical.
  11. Fulltext Epstein-Barr virus infection is associated with the nuclear factor-kappa B p65 signaling pathway in renal cell carcinoma
    Farhadi A, Namdari S, Chong PP, Geramizadeh B, Behzad-Behbahani A, Sekawi Z, et al.
    BMC Urol, 2022 Feb 07;22(1):17.
    PMID: 35130882 DOI: 10.1186/s12894-022-00964-2
    BACKGROUND: There have been few studies regarding viral involvement in the pathogenesis of renal cell carcinoma (RCC). The aim of this study was to examine the possible association of Epstein-Barr virus (EBV) infection with clinicopathological features and cellular biomarkers including p53, p16INK4a, Ki-67 and nuclear factor-kappa B (NF-κB) in RCC tumors.

    METHODS: In this prospective study, 122 histologically confirmed Formalin-fixed Paraffin-embedded RCC tissue specimens along with 96 specimens of their corresponding peritumoral tissues and 23 samples of blunt renal injuries were subjected to nested polymerase chain reaction (nPCR) in order to amplify EBV DNA sequences. The expression of p53, p16INK4a, Ki-67 and NF-κB was investigated by immunohistochemistry (IHC) assay. Statistical analysis was employed to demonstrate the possible associations.

    RESULTS: Infection with EBV was found to be significantly associated with RCC. Our results indicate that p65 NF-κB signaling pathway is probably involved in EBV-mediated RCC pathogenesis. Moreover, we found p53, Ki-67 and cytoplasmic NF-κB expression to be associated with tumor nuclear grade in RCC patients. The expression of p53 and Ki-67 was associated with primary tumor category as well. In addition, p53 overexpression was significantly more frequent among nonconventional RCC tumors than the conventional histologic type.

    CONCLUSIONS: Infection with EBV is likely to play an important role in the development of RCC through the constitutive and permanent activation of NF-κB p65 signaling pathway. However, more experiments and supporting data are required to reach a decisive conclusion.

  12. Detection of 10 medically important Candida species by seminested polymerase chain reaction
    Than LT, Chong PP, Ng KP, Seow HF
    Diagn Microbiol Infect Dis, 2012 Feb;72(2):196-8.
    PMID: 22154674 DOI: 10.1016/j.diagmicrobio.2011.10.008
    A seminested PCR detecting ten medically important Candida species were achieved. Analytical sensitivity and specificity were not compromised.
  13. Genotyping and drug resistance profile of Candida spp. in recurrent and one-off vaginitis, and high association of non-albicans species with non-pregnant status
    Chong PP, Abdul Hadi SR, Lee YL, Phan CL, Tan BC, Ng KP, et al.
    Infect Genet Evol, 2007 Jul;7(4):449-56.
    PMID: 17324639
    Recurrent vulvovaginal candidiasis affects women worldwide and the resistance to azole drugs may be an important factor. The extent of strain-to-strain variation within a species and its relationship to the ability of the organism to colonize the vulvovaginal mucosa is not well established. The aims of this study were to compare: (i) the genotypes of Candida strains in sequential infections in patients with recurrent vaginitis, (ii) the genotypes of strains in patients with only one episode of infection in a period of 1 year and (iii) determine the in vitro antifungal susceptibilities of strains that cause recurrent vaginitis. Fifty-one cultured specimens from six distinct Candida species were genotyped via random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) method using the ERIC1 and ERIC2 primers (ERIC, enterobacterial repetitive intergenic consensus). Statistical analyses allowed three different scenarios to be discerned for recurrent cases: (i) strain maintenance without genetic variation, (ii) strain maintenance with minor genetic variation and (iii) outright strain replacement. The genetic relatedness between strains from patients with recurrent vaginitis and patients with single episode of vaginitis were demonstrated by the dendogramme and the mean pairwise similarity coefficient S(AB) for the intergroup comparison was 0.223. However, intragroup genetic relatedness was slightly higher than intergroup comparison, with mean S(AB) of 0.261 and 0.331 for Groups I and II, respectively. A high proportion of Group I isolates (87.5%) causing recurrent infections were resistant to ketoconazole, whereas 41.7% of these isolates were cross-resistant to both clotrimazole and ketoconazole as shown by the in vitro antifungal susceptibility test, especially for C. glabrata isolates. Pregnancy status of patients displayed a highly significant association with C. albicans species whereas non-albicans species had a markedly higher prevalence in non-pregnant patients (p<0.001). These results may have a profound impact on the management of vaginal candidiasis, especially in recurrent cases.
  14. Fulltext Detection of medically important Candida species by absolute quantitation real-time polymerase chain reaction
    Than LT, Chong PP, Ng KP, Seow HF
    Jundishapur J Microbiol, 2015 Jan;8(1):e14940.
    PMID: 25789129 DOI: 10.5812/jjm.14940
    The number of invasive candidiasis cases has risen especially with an increase in the number of immunosuppressed and immunocom promised patients. The early detection of Candida species which is specific and sensitive is important in determining the correct administration of antifungal drugs to patients.
  15. Fulltext High prevalence of human papillomavirus DNA detected in cervical swabs from women in southern Selangor, Malaysia
    Chong PP, Asyikin N, Rusinahayati M, Halimatun S, Rozita R, Ng CK, et al.
    Asian Pac J Cancer Prev, 2010;11(6):1645-51.
    PMID: 21338211
    Persistent high-risk human papillomavirus (HPV) infection is known to play an important role in the genesis of cervical cancer. Since new screening and prevention strategies, namely improved HPV testing and HPV vaccination have been aggressively promoted recently, it is crucial to investigate the HPV distribution in Malaysia in order to maximize their cost-effectiveness. This study was therefore conducted to assess the HPV type distribution in the most populous region, the state of Selangor. A total of 200 cervical swab samples were collected in two health-screening campaigns, and also from women attending obstetrics and gynecology clinics in several hospitals in Selangor. DNA extraction was performed and HPV DNA was detected via nested PCR using MY09/MY11 as outer primers and GP5+/GP6+ as inner primers which target the L1 gene of the viral genome. The purified PCR products were subjected to automated DNA sequencing to determine the HPV genotype. Out of 180 β-globin positive samples, 84 (46.7%) were positive for HPV DNA. The most common HPV type found was high-risk oncogenic type 16 (40%), followed by HPV type 18 (3.3%), HPV 33 (1.7%), HPV 31 (0.6%), and low-risk HPV 87 (0.6%). Our study confirmed that nested PCR method is highly sensitive in detecting HPV DNA even in low risk patients. Since a relatively high prevalence rate of HPV infection was found in this population, prompt healthcare policy changes to bring about implementation of early HPV vaccination program is desirable to prevent a high incidence of cervical cancer.

    Study site: Gynaecology and Obstetrics Clinics in Selangor (Hospital Kajang, Hospital Serdang, and the Britannia Women and Children Specialist Centre)
  16. Clinical accuracy and agreement between tympanic and forehead body temperature measurements for screening of patients with COVID-19
    Sharif Nia H, Chong PP, Yiong Huak C, Gorgulu O, Taghipour B, Sivarajan Froelicher E, et al.
    J Clin Nurs, 2021 Dec 15.
    PMID: 34908206 DOI: 10.1111/jocn.16166
    AIM: To investigate the accuracy, reliability and agreement between infrared forehead thermometers versus infrared tympanic thermometers temperature, a cross-sectional study was conducted in April 2020.

    METHODS: The forehead and tympanic temperatures of 615 subjects were measured simultaneously in three exposed SARS-COV-2 groups at one hospital in Iran, during April 2020. These comparisons were evaluated by Bland-Altman Plot, repeatability, Passing-Bablok regression and Lin's concordance correlation coefficient. The receiver operating characteristic (ROC) analysis was done to describe the discrimination accuracy of a diagnostic test. The study adhered to STROBE checklist for cross-sectional studies.

    RESULTS: A Bland-Altman plot indicated that the limits of agreement between the forehead and tympanic temperature were -0.259 to +0.19°C. Passing-Bablok regression analysis illustrated that the infrared forehead was not linearly related to tympanic temperatures (reference method), with a slope estimate that was significantly different from 1.00. The infrared forehead thermometer showed poor precision and lower accuracy than the tympanic. The forehead temperature readings had 60.0% sensitivity and 44.4% specificity (p > .05) to predict disease.

    CONCLUSION: According to the results of study, there is no evidence that the assessment of temperature by infrared forehead thermometer could discriminate between the two groups (positive and negative).

  17. Chondrogenic potential of physically treated bovine cartilage matrix derived porous scaffolds on human dermal fibroblast cells
    Moradi A, Ataollahi F, Sayar K, Pramanik S, Chong PP, Khalil AA, et al.
    J Biomed Mater Res A, 2016 Jan;104(1):245-56.
    PMID: 26362913 DOI: 10.1002/jbm.a.35561
    Extracellular matrices have drawn attention in tissue engineering as potential biomaterials for scaffold fabrication because of their bioactive components. Noninvasive techniques of scaffold fabrication and cross-linking treatments are believed to maintain the integrity of bioactive molecules while providing proper architectural and mechanical properties. Cartilage matrix derived scaffolds are designed to support the maintenance of chondrocytes and provide proper signals for differentiation of chondroinducible cells. Chondroinductive potential of bovine articular cartilage matrix derived porous scaffolds on human dermal fibroblasts and the effect of scaffold shrinkage on chondrogenesis were investigated. An increase in sulfated glycosaminoglycans production along with upregulation of chondrogenic genes confirmed that physically treated cartilage matrix derived scaffolds have chondrogenic potential on human dermal fibroblasts.
  18. Fulltext Inhibition of hyphae formation and SIR2 expression in Candida albicans treated with fresh Allium sativum (garlic) extract
    Low CF, Chong PP, Yong PV, Lim CS, Ahmad Z, Othman F
    J Appl Microbiol, 2008 Dec;105(6):2169-77.
    PMID: 19120662 DOI: 10.1111/j.1365-2672.2008.03912.x
    The aims of the present study were to determine whether Allium sativum (garlic) extract has any effect on the morphology transformation of Candida albicans, and to investigate whether it could alter the gene expression level of SIR2, a morphogenetic control gene and SAP4, a gene encoding secreted aspartyl proteinase.
  19. Genetic relatedness of Candida strains isolated from women with vaginal candidiasis in Malaysia
    Chong PP, Lee YL, Tan BC, Ng KP
    J Med Microbiol, 2003 Aug;52(Pt 8):657-66.
    PMID: 12867559
    The aims of this study were to compare the genetic relatedness of: (i) sequential and single isolates of Candida strains from women with recurrent vaginal candidiasis (RVC); and (ii) Candida strains from women who had only one episode of infection within a 1-year period. In total, 87 isolates from 71 patients were cultured, speciated and genotyped by random amplification of polymorphic DNA (RAPD) analysis. Patients were categorized into three groups, namely those with: (i) a history of RVC from whom two or more yeast isolates were obtained (group A); (ii) a history of RVC from whom only a single isolate was obtained (group B); and (iii) a single episode of vaginal candidiasis within a 1-year period (group C). Six yeast species were detected: Candida albicans, Candida glabrata, Candida lusitaniae, Candida famata, Candida krusei and Candida parapsilosis. Interestingly, the prevalence of non-albicans species was higher in group A patients (50 %) than in patients in groups B (36 %) or C (18.9 %). Eighty RAPD profiles were observed, with a total of 61 polymorphic PCR fragments of distinct sizes. Clustering analysis showed that, overall, the majority of patients in group A had recurrent infections caused by highly similar, but not identical, sequential strains [mean pairwise similarity coefficient (S(AB)) = 0.721 +/- 0.308]. The range of mean S(AB) values for intergroup comparisons for C. albicans isolates alone was 0.50-0.56, suggesting that there was no significant relatedness between strains from different groups. Genetic similarity of C. albicans isolates from patients in group A was lower than that of C. albicans isolates from patients in group C (mean S(AB) = 0.532 +/- 0.249 and 0.636 +/- 0.206, respectively); this difference was statistically significant (P = 0.036). These results demonstrate that the cause of recurrent infections varies among individuals and ranges between strain maintenance, strain microevolution and strain replacement; the major scenario is strain maintenance with microevolution. They also show that C. albicans strains that cause recurrent infections are less similar to each other than strains that cause one-off infections, suggesting that the former may represent more virulent subtypes.
  20. Recurrent candidaemia in a neonate with Hirschsprung's disease: fluconazole resistance and genetic relatedness of eight Candida tropicalis isolates
    Chong PP, Chieng DC, Low LY, Hafeez A, Shamsudin MN, Seow HF, et al.
    J Med Microbiol, 2006 Apr;55(Pt 4):423-428.
    PMID: 16533990 DOI: 10.1099/jmm.0.46045-0
    The incidence of candidaemia among immunocompromised patients in Malaysia is increasing at an alarming rate. Isolation of clinical strains that are resistant to fluconazole has also risen markedly. We report here the repeated isolation of Candida tropicalis from the blood of a neonatal patient with Hirschsprung's disease. In vitro fluconazole susceptibility tests of the eight isolates obtained at different time points showed that seven of the isolates were resistant and one isolate was scored as susceptible dose-dependent. Random amplification of polymorphic DNA fingerprinting of the isolates using three primers and subsequent phylogenetic analysis revealed that these isolates were highly similar strains having minor genetic divergence, with a mean pairwise similarity coefficient of 0.893+/-0.041. The source of the infectious agent was thought to be the central venous catheter, as culture of its tip produced fluconazole-resistant C. tropicalis. This study demonstrates the utility of applying molecular epidemiology techniques to complement traditional mycological culture and drug susceptibility tests for accurate and appropriate management of recurrent candidaemia and highlights the need for newer antifungals that can combat the emergence of fluconazole-resistant C. tropicalis strains.
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