MyMedR

Urine as a diagnostic specimen for the detection of Chlamydia trachomatis in Malaysia by ligase chain reaction

Gaydos CA, Ngeow YF, Lee HH, Canavaggio M, Welsh LE, Johanson J, et al.

Sex Transm Dis, 1996 9 1;23(5):402-6.

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.

Young Malaysian children with lower respiratory tract infections show low incidence of chlamydial infection

Ngeow YF, Weil AF, Khairullah NS, Yusof MY, Luam L, Gaydos C, et al.

J Paediatr Child Health, 1997 Oct;33(5):422-5.

PMID: 9401887

OBJECTIVE: The incidence of Chlamydia pneumoniae and Chlamydia trachomatis infection was studied among infants and young children admitted to hospital for the management of lower respiratory tract infections, over a 12 month period.

METHODOLOGY: Respiratory secretions were examined for chlamydiae by cell culture, enzyme-linked immunosorbent assay and polymerase chain reaction-enzyme immunoassay. Sera were tested by micro-immunofluorescence for chlamydial IgG, IgM and IgA. Other bacterial and viral pathogens were also looked for by standard cultural and serological methods.

RESULTS: Of 87 patients aged 2 months-3 years, an aetiologic diagnosis was made in 41 (47.1%). C. pneumoniae and C. trachomatis were each detected in 1 (1.2%) of the patients. Among common bacterial pathogens, Haemophilus influenzae (13.8%) and Streptococcus pneumoniae (8.1%) were the most frequently identified. Respiratory viruses and elevated Mycoplasma pneumoniae antibodies were found in 10.3% and 9.1% of patients, respectively.

CONCLUSION: Chlamydiae are infrequent causes of community-acquired acute lower respiratory tract infections in infants and very young children in Malaysia.

Fulltext Rapid detection of Haemophilus ducreyi in clinical and experimental infections using monoclonal antibody: a preliminary evaluation

Karim QN, Finn GY, Easmon CS, Dangor Y, Dance DA, Ngeow YF, et al.

Genitourin Med, 1989 Dec;65(6):361-5.

PMID: 2693334

A monoclonal antibody raised against Haemophilus ducreyi was tested for its sensitivity and specificity as an immunofluorescence (IF) reagent using simulated vaginal smears containing H. ducreyi, smears taken from skin lesions of mice infected with H. ducreyi and patients from South Africa, Thailand and Malaysia with clinically diagnosed chancroid. The IF test was more sensitive than culture or Gram staining in the simulated smears, theoretically detecting less than 4 organisms/sample. It detected H. ducreyi in 95% of the animal lesions compared with 14% detected by culture. Immunofluorescence testing identified over 90% of culture-positive cases of chancroid but also detected organisms in some culture-negative cases where clinical evidence for the diagnosis was strong. These results suggest that this antibody may provide a simple, rapid and sensitive means of detecting H. ducreyi in cases of chancroid.

Genital infections with chlamydia trachomatis

Ngeow YF, Ong SB, Thong ML, Teoh SK, Omar R, Low BT

Med J Malaysia, 1979 Sep;34(1):65-70.

PMID: 542157

Fulltext Ureaplasma urealyticum and Mycoplasma hominis isolation from cervical secretions of pregnant women and nasopharyngeal secretions of their babies at delivery

Chua KB, Ngeow YF, Ng KB, Chye JK, Lim CT

Singapore Med J, 1998 Jul;39(7):300-2.

PMID: 9885690

A prospective study was carried out at the University Hospital, Kuala Lumpur to determine the cervical carriage rate of Ureaplasma urealyticum and Mycoplasma hominis among healthy pregnant women at delivery and the incidence of nasopharyngeal colonisation among their infants.

An immunogenic epitope of Chlamydia pneumoniae from a random phage display peptide library is reactive with both monoclonal antibody and patients sera

Naidu BR, Ngeow YF, Wang LF, Chan L, Yao ZJ, Pang T

Immunol Lett, 1998 Jun;62(2):111-5.

PMID: 9698107

Random 15-mer peptides displayed on filamentous phages were screened in binding studies using a Chlamydia pneumoniae-specific monoclonal antibody (RR-402) and affinity-purified, polyclonal sera from patients seropositive for C. pneumoniae infections by the microimmunofluorescence (MIF) test. One 15-mer epitope, epitope Cpnl5A (LASLCNPKPSDAPVT) was identified in both the monoclonal and polyclonal screenings, and showed higher ELISA reactivity with C. pneumoniae MIF-positive sera compared to patients with other chlamydial infections, non-chlamydial respiratory infections and normal healthy sera (MIF-negative). Interestingly, epitope Cpnl5A also showed significant (52%) amino acid sequence homology to the 56 kDa type-specific antigen of Rickettsia tsutsugamushi, a protein implicated in the virulence of this organism.

Fulltext Draft Genome Sequence of a Clinical Isolate of Mycobacterium tuberculosis Strain PR05

Ismail A, Teh LK, Ngeow YF, Norazmi MN, Zainul ZF, Tang TH, et al.

Genome Announc, 2013;1(3).

PMID: 23788553 DOI: 10.1128/genomeA.00397-13

We report the annotated genome sequence of a clinical isolate, Mycobacterium tuberculosis strain PR05, which was isolated from the human cerebrospinal fluid of a patient diagnosed with tuberculosis.

Tuberculosis in captive Asian elephants (Elephas maximus) in Peninsular Malaysia

Ong BL, Ngeow YF, Razak MF, Yakubu Y, Zakaria Z, Mutalib AR, et al.

Epidemiol Infect, 2013 Jul;141(7):1481-7.

PMID: 23414617 DOI: 10.1017/S0950268813000265

A cross-sectional study was conducted from 10 January to 9 April 2012, to determine the seroprevalence of tuberculosis (TB) of all captive Asian elephants and their handlers in six locations in Peninsular Malaysia. In addition, trunk-wash samples were examined for tubercle bacillus by culture and polymerase chain reaction (PCR). For 63 elephants and 149 elephant handlers, TB seroprevalence was estimated at 20.4% and 24.8%, respectively. From 151 trunkwash samples, 24 acid-fast isolates were obtained, 23 of which were identified by hsp65-based sequencing as non-tuberculous mycobacteria. The Mycobacterium tuberculosis-specific PCR was positive in the trunk-wash samples from three elephants which were also seropositive. Conversely, the trunk wash from seven seropositive elephants were PCR negative. Hence, there was evidence of active and latent TB in the elephants and the high seroprevalence in the elephants and their handlers suggests frequent, close contact, two-way transmission between animals and humans within confined workplaces.

Fulltext The identification of novel Mycobacterium tuberculosis DHFR inhibitors and the investigation of their binding preferences by using molecular modelling

Hong W, Wang Y, Chang Z, Yang Y, Pu J, Sun T, et al.

Sci Rep, 2015;5:15328.

PMID: 26471125 DOI: 10.1038/srep15328

It is an urgent need to develop new drugs for Mycobacterium tuberculosis (Mtb), and the enzyme, dihydrofolate reductase (DHFR) is a recognised drug target. The crystal structures of methotrexate binding to mt- and h-DHFR separately indicate that the glycerol (GOL) binding site is likely to be critical for the function of mt-DHFR selective inhibitors. We have used in silico methods to screen NCI small molecule database and a group of related compounds were obtained that inhibit mt-DHFR activity and showed bactericidal effects against a test Mtb strain. The binding poses were then analysed and the influence of GOL binding site was studied by using molecular modelling. By comparing the chemical structures, 4 compounds that might be able to occupy the GOL binding site were identified. However, these compounds contain large hydrophobic side chains. As the GOL binding site is more hydrophilic, molecular modelling indicated that these compounds were failed to occupy the GOL site. The most potent inhibitor (compound 6) demonstrated limited selectivity for mt-DHFR, but did contain a novel central core (7H-pyrrolo[3,2-f]quinazoline-1,3-diamine), which may significantly expand the chemical space of novel mt-DHFR inhibitors. Collectively, these observations will inform future medicinal chemistry efforts to improve the selectivity of compounds against mt-DHFR.

An overview of the phenotypic and genotypic characteristics of multidrug-resistant Mycobacterium tuberculosis isolates from four Asian countries

Ang CF, Ong CS, Rukmana A, Pham Thi KL, Yap SF, Ngeow YF, et al.

J Med Microbiol, 2008 Aug;57(Pt 8):1039-1040.

PMID: 18628510 DOI: 10.1099/jmm.0.47850-0

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