Displaying publications 1 - 20 of 46 in total

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  1. Ngeow Y
    Malays J Pathol, 2000 Dec;22(2):55-64.
    PMID: 16329536
    The application of modern research tools has broadened our understanding of the chlamydiae and their role in disease. Chlamydial genome analysis showed the presence of genes for ATP and peptidoglycan synthesis, contradicting the common belief that chlamydiae lack the ability to produce these compounds. Phylogenetic tree analysis suggests that chlamydiae could have evolved from an intracellular existence in amoebae. Newly discovered obligate intracellular organisms with chlamydia-like life-cycles have been classified as chlamydiae by rRNA homology with existing chlamydial species. A proposed new classification adds three new families to the order Chlamydiales as well as creates two genera and nine species within the family Chlamydiaceae. Chlamydiae are incriminated in an increasingly large spectrum of diseases both in humans and in animals. The emergence of multi-drug resistant C. trachomatis strains forewarns therapeutic problems with this organism. While C. pneumoniae remains a significant respiratory pathogen, the role it plays in the pathogenesis of atherosclerosis and ischaemic heart disease awaits definition.
    Matched MeSH terms: Chlamydia/classification; Chlamydia/genetics*; Chlamydia/pathogenicity*; Chlamydia Infections/genetics; Chlamydia Infections/microbiology*; Chlamydia Infections/pathology
  2. Lam SS, Waugh C, Peng W, Sonne C
    Science, 2020 02 14;367(6479):750.
    PMID: 32054755 DOI: 10.1126/science.aba8372
    Matched MeSH terms: Chlamydia Infections*
  3. Cheong HC, Cheok YY, Chan YT, Tang TF, Sulaiman S, Looi CY, et al.
    BMC Microbiol, 2023 Mar 04;23(1):58.
    PMID: 36870960 DOI: 10.1186/s12866-023-02802-3
    BACKGROUND: Genital Chlamydia trachomatis infection is the most common bacterial sexual transmitted disease that causes severe complications including pelvic inflammatory disease, ectopic pregnancy, and infertility in females. The Pgp3 protein encoded by C. trachomatis plasmid has been speculated to be an important player in chlamydial pathogenesis. However, the precise function of this protein is unknown and thus remains to be thoroughly investigated.

    METHODS: In this study, we synthesized Pgp3 protein for in vitro stimulation in the Hela cervical carcinoma cells.

    RESULTS AND CONCLUSION: We showed that Pgp3 induced prominent expression of host inflammatory cytokine genes including interleukin-6 (IL-6), IL-8, tumor necrosis factor alpha-induced protein 3 (TNFAIP3), and chemokine C-X-C motif ligand 1 (CXCL1), implying a possible role of Pgp3 in modulating the inflammatory reaction in the host.

    Matched MeSH terms: Chlamydia Infections*; Chlamydia trachomatis
  4. Rachagan SP, Ngeow YF
    Med J Malaysia, 1990 Dec;45(4):298-303.
    PMID: 2152050
    Thirty-six asymptomatic infertile women undergoing laparoscopic examination as part of their infertility investigations, were included in this study on chlamydial infection. Patients were tested for chlamydial antigen in the cervix and peritoneal fluid. The serum of twenty-five of these patients was titrated for evidence of chlamydial antibodies. Fifty women attending a family planning clinic were used as a control group. The study showed a strong relationship between chlamydial infection and infertility due to tubal pathology. The incidence of chlamydial infection in asymptomatic infertile women was 33.3%. The results indicate that Chlamydia trachomatis should be sought in patients presenting with infertility and, if detected, appropriate medical treatment be given.
    Matched MeSH terms: Chlamydia Infections/complications*; Chlamydia trachomatis*
  5. Bahnu S, Ngeow YF, Wong WK
    JUMMEC, 1996;1:52-56.
    Matched MeSH terms: Chlamydia
  6. Ngeow YF
    Ann Acad Med Singap, 1996 Mar;25(2):300-4.
    PMID: 8799029
    Infection with Chlamydia trachomatis results in the formation of a variety of antibodies with group, species, subspecies and serovarspecificity. Sera from patients with genital tract infections often show broad reactivity in serological tests. This may be due to the presence of cross-reacting antibodies, repeated infections by different serotypes or concurrent genital and respiratory infections by different chlamydial species. Other factors contributing to difficulties in interpretation include how antibody titres in acute mucosal infections, the occurrence of latent infections and reactivations, and the persistence of IgG which does not allow the differentiation of past from current infections. For these reasons, serology alone is inadequate for the diagnosis of uncomplicated lower genital tract infections. In upper genital tract infections, however, because of difficulties with sampling from the infected site, a positive serology may be the only indications of chlamydial involvement. This paper discusses the principles of chlamydial antibody assays, difficulties with their interpretation and their role in the diagnosis of upper and lower genital tract infections.
    Matched MeSH terms: Chlamydia Infections/diagnosis*; Chlamydia Infections/immunology; Chlamydia trachomatis/immunology*; Chlamydia trachomatis/isolation & purification
  7. Yeow TC, Wong WF, Sabet NS, Sulaiman S, Shahhosseini F, Tan GM, et al.
    BMC Microbiol, 2016 Mar 18;16:45.
    PMID: 26987367 DOI: 10.1186/s12866-016-0671-1
    BACKGROUND: The 7.5 kb cryptic plasmid of Chlamydia trachomatis has been shown to be a virulence factor in animal models, but its significance in humans still remains unknown. The aim of this study was to investigate the prevalence and potential involvement of the C. trachomatis cryptic plasmid in causing various clinical manifestations; including infertility, reproductive tract disintegrity, menstrual disorder, and polycystic ovarian syndrome (PCOS) among genital C. trachomatis-infected patients.
    RESULTS:A tot l of 180 female patients of child bearing age (mean 30.9 years old, IQR:27-35) with gynecological complications and subfertility issues, who visited Obstetrics and Gynecology clinics in Kuala Lumpur, Malaysia were recruited for the study. Prevalence of genital chlamydial infection among these patients was alarmingly high at 51.1% (92/180). Of the 92 chlamydia-infected patients, 93.5% (86/92) were infected with plasmid-bearing (+) C. trachomatis while the remaining 6.5% (6/92) were caused by the plasmid-free (-) variant. Our data showed that genital C. trachomatis infection was associated with infertility issues, inflammation in the reproductive tract (mucopurulent cervicitis or endometriosis), irregular menstrual cycles and polycystic ovarian syndrome (PCOS). However, no statistical significance was detected among patients with plasmid (+) versus plasmid (-) C. trachomatis infection. Interestingly, plasmid (+) C. trachomatis was detected in all patients with PCOS, and the plasmid copy numbers were significantly higher among PCOS patients, relative to non-PCOS patients.
    CONCLUSION: Our findings show a high incidence of C. trachomatis infection among women with infertility or gynecological problems in Malaysia. However, due to the low number of plasmid (-) C. trachomatis cases, a significant role of the plasmid in causing virulence in human requires further investigation of a larger cohort.
    KEYWORDS: Chlamydia trachomatis; Infertility; Plasmid; Reproductive system disorders
    Study site: Obstetrics and Gynecology clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
    Matched MeSH terms: Chlamydia Infections/microbiology*; Chlamydia trachomatis/classification; Chlamydia trachomatis/genetics*; Chlamydia trachomatis/isolation & purification*; Chlamydia trachomatis/metabolism
  8. Chan YT, Cheok YY, Cheong HC, Tan GMY, Seow SR, Tang TF, et al.
    Immunol Cell Biol, 2023 Apr;101(4):305-320.
    PMID: 36658328 DOI: 10.1111/imcb.12621
    Genital Chlamydia trachomatis infection remains a major health issue as it causes severe complications including pelvic inflammatory disease, ectopic pregnancy and infertility in females as a result of infection-associated chronic inflammation. Podoplanin, a transmembrane receptor, has been previously reported on inflammatory macrophages. Thus, strategies that specifically target podoplanin might be able to reduce local inflammation. This study investigated the expression level and function of podoplanin in a C. trachomatis infection model. C57BL/6 mice infected with the mouse pathogen Chlamydia muridarum were examined intermittently from days 1 to 60 using flow cytometry analysis. Percentages of conventional macrophages (CD11b+ CD11c- F4/80+ ) versus inflammatory macrophages (CD11b+ CD11c+ F4/80+ ), and the expression of podoplanin in these cells were investigated. Subsequently, a podoplanin-knockout RAW264.7 cell was used to evaluate the function of podoplanin in C. trachomatis infection. Our findings demonstrated an increased CD11b+ cell volume in the spleen at day 9 after the infection, with augmented podoplanin expression, especially among the inflammatory macrophages. A large number of podoplanin-expressing macrophages were detected in the genital tract of C. muridarum-infected mice. Furthermore, analysis of the C. trachomatis-infected patients demonstrated a higher percentage of podoplanin-expressing monocytes than that in the noninfected controls. Using an in vitro infection in a transwell migration assay, we identified that macrophages deficient in podoplanin displayed defective migratory function toward C. trachomatis-infected HeLa 229 cells. Lastly, using immunoprecipitation-mass spectrometry method, we identified two potential podoplanin interacting proteins, namely, Cofilin 1 and Talin 1 actin-binding proteins. The present study reports a role of podoplanin in directing macrophage migration to the chlamydial infection site. Our results suggest a potential for reducing inflammation in individuals with chronic chlamydial infections by targeting podoplanin.
    Matched MeSH terms: Chlamydia Infections*; Chlamydia trachomatis/physiology; Chlamydia muridarum
  9. Chan RK, Tan HH
    Ann Acad Med Singap, 2003 Jan;32(1):25-8.
    PMID: 12625094
    INTRODUCTION: This is a review of sexual knowledge, behaviour and the extent of sexually transmitted infections (STI), including human immunodeficiency virus (HIV) infection, in Singapore adolescents.

    METHODS: Data were retrieved from relevant studies, reports and statistics concerning STI and HIV in Singapore.

    RESULTS: For many reasons, adolescents are at a higher risk of acquiring STI and HIV infections. Adolescents in Singapore are still relatively conservative in their sexual attitudes and behaviour. Most of those who had sex never used condoms. Fortunately, the incidence of STI and HIV infections among adolescents is relatively low. However, this may be changing, and there is a proportion of individuals who exhibit higher risk behaviours.

    CONCLUSIONS: In this age of rapidly changing morals and values, accurate information and skills need to be provided to young people to ensure that they are adequately prepared to protect themselves from acquiring STI/HIV infection.

    Matched MeSH terms: Chlamydia Infections/epidemiology; Chlamydia trachomatis
  10. Wong WF, Chambers JP, Gupta R, Arulanandam BP
    J Pathog, 2019;2019:8604958.
    PMID: 31467721 DOI: 10.1155/2019/8604958
    The increasing number of new cases of Chlamydia infection worldwide may be attributed to the pathogen's ability to evade various host immune responses. Summarized here are means of evasion utilized by Chlamydia enabling survival in a hostile host environment. The pathogen's persistence involves a myriad of molecular interactions manifested in a variety of ways, e.g., formation of membranous intracytoplasmic inclusions and cytokine-induced amino acid synthesis, paralysis of phagocytic neutrophils, evasion of phagocytosis, inhibition of host cell apoptosis, suppression of antigen presentation, and induced expression of a check point inhibitor of programmed host cell death. Future studies could focus on the targeting of these molecules associated with immune evasion, thus limiting the spread and tissue damage caused by this pathogen.
    Matched MeSH terms: Chlamydia; Chlamydia Infections
  11. Cheong YM, Wong WK, Ngeow YF
    Singapore Med J, 1993 Aug;34(4):352-3.
    PMID: 8266214
    A first case of Chlamydia pneumoniae pneumonia in Malaysia is reported. The diagnosis was made by a significant change in C. pneumoniae antibody titre. The infection responded well to a course of erythromycin.
    Matched MeSH terms: Chlamydia Infections/pathology*
  12. Ravindran J, Tan YI, Ngeow YF
    Med J Malaysia, 1998 Mar;53(1):16-21.
    PMID: 10968132
    Chlamydia trachomatis is recognized as the most prevalent sexually transmitted organism in many parts of the world. Most complications associated with chlamydial infection in women and their infants can be avoided by appropriate treatment. However, treatment is often not initiated because infections are frequently asymptomatic. The identification of at risk patients and treatment of these patients is a practical clinical approach in the reduction of transmission and prevention of complications. The prevalence of chlamydial infection among patients with pelvic inflammatory disease admitted to Seremban General Hospital was 22.7%. The difference in seropositivity between PID patients (20.5%) and antenatal controls (2.3%) was statistically significant. The corresponding cervical antigen detection rates were 6.8% and 2.3% respectively. Chlamydial infection should be screened for in gynaecological patients and antibiotic policies should take cognizance of the aetiological role played by this organism in pelvic inflammatory disease.
    Matched MeSH terms: Chlamydia Infections/complications*; Chlamydia trachomatis/isolation & purification*
  13. Lazarev VN, Polina NF, Shkarupeta MM, Kostrjukova ES, Vassilevski AA, Kozlov SA, et al.
    Antimicrob Agents Chemother, 2011 Nov;55(11):5367-9.
    PMID: 21876050 DOI: 10.1128/AAC.00449-11
    Spider venoms are vast natural pharmacopoeias selected by evolution. The venom of the ant spider Lachesana tarabaevi contains a wide variety of antimicrobial peptides. We tested six of them (latarcins 1, 2a, 3a, 4b, 5, and cytoinsectotoxin 1a) for their ability to suppress Chlamydia trachomatis infection. HEK293 cells were transfected with plasmid vectors harboring the genes of the selected peptides. Controlled expression of the transgenes led to a significant decrease of C. trachomatis viability inside the infected cells.
    Matched MeSH terms: Chlamydia Infections/prevention & control*; Chlamydia trachomatis/pathogenicity
  14. Ngeow YF, Ong SB, Thong ML, Teoh SK, Omar R, Low BT
    Med J Malaysia, 1979 Sep;34(1):65-70.
    PMID: 542157
    Matched MeSH terms: Chlamydia Infections/diagnosis*; Chlamydia trachomatis/isolation & purification
  15. 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.
    Matched MeSH terms: Chlamydia Infections/diagnosis*; Chlamydia Infections/microbiology; Chlamydia trachomatis/genetics; Chlamydia trachomatis/immunology; Chlamydia trachomatis/isolation & purification*
  16. Cheong HC, Yap PSX, Chong CW, Cheok YY, Lee CYQ, Tan GMY, et al.
    PLoS One, 2019;14(11):e0224658.
    PMID: 31738795 DOI: 10.1371/journal.pone.0224658
    The cervical microbiota constitutes an important protective barrier against the invasion of pathogenic microorganisms. A disruption of microbiota within the cervical milieu has been suggested to be a driving factor of sexually transmitted infections. These include Chlamydia trachomatis which frequently causes serious reproductive sequelae such as infertility in women. In this study, we profiled the cervical microbial composition of a population of 70 reproductive-age Malaysian women; among which 40 (57.1%) were diagnosed with genital C. trachomatis infection, and 30 (42.8%) without C. trachomatis infection. Our findings showed a distinct compositional difference between the cervical microbiota of C. trachomatis-infected subjects and subjects without C. trachomatis infection. Specifically, significant elevations of mostly strict and facultative anaerobes such as Streptococcus, Megasphaera, Prevotella, and Veillonella in the cervical microbiota of C. trachomatis-positive women were detected. The results from the current study highlights an interaction of C. trachomatis with the environmental microbiome in the endocervical region.
    Matched MeSH terms: Chlamydia Infections/complications; Chlamydia Infections/immunology; Chlamydia Infections/microbiology*; Chlamydia trachomatis/isolation & purification*; Chlamydia trachomatis/pathogenicity
  17. Low LC, Tan FL, Chan E, Chio M, Chan R, Sen P
    Sex Health, 2013 Nov;10(5):470-1.
    PMID: 24074902 DOI: 10.1071/SH13095
    BACKGROUND: Chlamydia (Chlamydia trachomatis) is the most commonly diagnosed sexually transmissible infection (STI) in Singapore, with rising incidence.
    METHOD: Random sampling was performed on all chlamydia-positive samples collected from female patients who attended a women's clinic from January 2010 to December 2010. Some 250 electronic medical records were analysed. Population demographics, sexual histories, symptoms, diagnostic methods and management were recorded.
    RESULTS: One hundred and forty-two (56.8%) patients were under 25 years of age. The predominant race diagnosed with Chlamydia cervicitis were Chinese (116 cases, 46.4%) followed by 86 (34.4%) Malays and 20 (8%) Filipinos. Sixty-three (25.2%) were skilled workers and (47) 18.8% were students. Professionals and office workers together formed 68 (27.2%) of the patients. Some 248 (99.2%) patients were heterosexual and 2 (0.8%) patients were bisexual; 229 (91.6%) patients had regular partners, 18 (7.2%) had casual partners and 3 (1.2%) had both. Concurrency prevalence accounted for 49 cases (19.6%) and condom use was less common. Patients were generally asymptomatic, with 114 (45.5%) presenting with symptoms. One hundred and eight (43.2%) patients had 2-5 sexual partners in their lifetime. Patients with a termination made up 12% of our cohort. This episode of infection was the first diagnosis of an STI for 198 (79.2%) patients; 24 (9.6%) of patients had been previously diagnosed with chlamydia.
    CONCLUSION: Chlamydia infection was most prevalent in skilled workers and their regular partners with heterosexual practices under 25 years old. Most patients had 2-5 sexual partners and did not use condoms consistently or at all.
    Matched MeSH terms: Chlamydia Infections/drug therapy*; Chlamydia Infections/epidemiology*; Chlamydia trachomatis*
  18. Gaydos CA, Ngeow YF, Lee HH, Canavaggio M, Welsh LE, Johanson J, et al.
    Sex Transm Dis, 1996 9 1;23(5):402-6.
    PMID: 8885072
    BACKGROUND AND OBJECTIVES: Noninvasive urine screening for Chlamydia trachomatis infections offers a valuable public health tool, which could be of vast importance in chlamydial control programs. The authors evaluated a new DNA amplification method, ligase chain reaction (LCR).

    GOALS: The goal was to ascertain whether urine testing could be used as screening method to detect C. trachomatis infections in commercial sex workers, patients at sexually transmitted diseases clinic, and asymptomatic patients in Kuala Lumpur, Malaysia.

    METHODS: First-void urine specimens from 300 men and 300 women were tested by LCR, as well as by a commercially available enzyme immunoassay. The LCR assay amplifies specific sequences within the chlamydial plasmid with ligand-labeled probes, and the resultant amplicons are detected by an automated immunoassay. Specimens with discrepant results were confirmed by another LCR of the specimen that targeted the gene for the major outer membrane protein (OMP1).

    RESULTS: There were 31 LCR-positive male urine and 37 LCR-positive female urine specimens. The resolved sensitivity and specificity for the LCR of the male urine specimens were 100% and 99.6%, respectively, whereas for female urine specimens, the sensitivity and specificity were 100% and 98.5%, respectively. After resolution of discrepant test results by OMP1 LCR, the prevalence was 10% for men and 11% for women. The urine enzyme immunoassay was not useful in diagnosing C. trachomatis infections in either men or women, as the resolved sensitivities were 10% and 15.2%, respectively. The specificities were 99.6% for men and 98.9% for women.

    CONCLUSIONS: Testing first-void urine specimens by LCR is a highly sensitive and specific method to diagnose C. trachomatis infections in men and women, providing health care workers and public health officials with a new molecular amplification assay that uses noninvasive urine specimens for population-based screening purposes.

    Matched MeSH terms: Chlamydia Infections/prevention & control; Chlamydia Infections/urine*; Chlamydia trachomatis*
  19. Ngeow YF, Rachagan SP, Ramachandran S
    J Clin Pathol, 1990 May;43(5):400-2.
    PMID: 2196283
    A single antigen indirect immunofluorescence test was used to screen for chlamydial antibody among Malaysian infants, children, sexually active adults and prostitutes. Of 794 serum samples tested, 361 (45.5%) were positive. Seropositivity increased with age and sexual activity and ranged from 10 to 16% among children under 10 years old to 94.4% among prostitutes. Pregnant women and female adolescents showed a higher antibody prevalence than nonpregnant and older women. Six (13%) infants under 6 months of age were positive for chlamydial IgM.
    Matched MeSH terms: Chlamydia/immunology*; Chlamydia Infections/immunology; Chlamydia Infections/epidemiology
  20. Situ SF, Ding CH, Nawi S, Johar A, Ramli R
    Malays J Pathol, 2017 Apr;39(1):25-31.
    PMID: 28413202 MyJurnal
    BACKGROUND: Chlamydia trachomatis and Neisseria gonorrhoeae are important bacterial pathogens of sexually transmitted infections (STIs) worldwide. This study sought to compare the analytical sensitivity and specificity of conventional methods against a rapid molecular method in detecting STIs caused by these bacteria.

    METHODS: Ninety five first-time male attendees of the Genito-urinary Medicine Clinic in Hospital Kuala Lumpur were included in this cross-sectional study. The detection of C. trachomatis was achieved through direct fluorescence antibody (DFA) staining of urethral swabs and real-time polymerase chain reaction testing (Xpert® CT/NG assay) on urine specimens. N. gonorrhoeae was detected through Gram staining and culture of urethral swabs and Xpert® CT/ NG assay on urine specimens.

    RESULTS: From the Xpert® CT/NG results, 11 (11.6%) attendees had chlamydia, 23 (24.2%) had gonorrhoea and 8 (8.4%) had both STIs. The sensitivity and specificity of DFA in detecting chlamydia compared to Xpert® CT/NG were 5.3% (95% CI: 0-28) and 94.7% (95% CI: 86-98), respectively. For gonorrhoea, the sensitivity and specificity of Gram staining were 90.3% (95% CI: 73-98) and 95.3% (86-99), respectively, whereas the sensitivity and specificity of culture compared to Xpert® CT/NG were 32.2% (95% CI: 17-51) and 100% (95% CI: 93-100), respectively.

    CONCLUSION: Although Gram-stained urethral swab smears are sensitive enough to be retained as a screening tool for gonorrhoea, culture as well as DFA lack sensitivity and are poorly suited to screen for gonorrhoea and chlamydia, respectively. However, owing to their high specificity, conventional detection methods are still suitable as confirmatory tests for gonorrhoea and chlamydia.

    Matched MeSH terms: Chlamydia Infections/diagnosis; Chlamydia Infections/virology; Chlamydia trachomatis/genetics*
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