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.
A case of respiratory infection in a child due to Chlamydia pneumoniae is reported. The diagnosis was made by the detection of chlamydial antigen in the tracheal secretion and a significant increase in C. pneumoniae antibody titre. The infection responded well to erythromycin therapy.
The prevalence of sexually transmitted diseases was determined among 370 prostitutes in Kuala Lumpur, Malaysia. Chlamydial cervicitis (26.5%) was detected more frequently than gonorrhoea (14.25%) and was associated more often with pelvic inflammatory disease. Concurrent infections and asymptomatic infections were common. Seropositivity to hepatitis B and syphilis were 66.3% and 13.6% respectively. Women under 20 years of age had significantly higher rates of infection with Chlamydia trachomatis and hepatitis B virus than older women.
Study site: private clinic, Kuala Lumpur, Malaysia
Fourteen severely ill ventilated patients in an intensive care unit, requiring short-term total parenteral nutrition, were examined for catheter-related infection. Microbiological analysis using Maki's SQ technique was carried out on catheter exit site, catheter hub, proximal subcutaneous segment of catheter and catheter up. Qualitative cultures were carried out on total parenteral nutrition and peripheral blood samples. Twenty six of 29 catheters removed (90%) were culture positive but only 7 catheters were related to positive blood cultures, giving a catheter-related bacteremia (CRB) rate of 24%. Haematogenous seeding was strongly implicated in 7/29 (24%) of catheters. Patients' skin flora appeared to be the main source of catheter-related infection. The organisms isolated for patients with CRB included coagulase-negative staphylococci, Acinetobacter and Klebsiella. It is suggested that to control infective complications of central venous catheters, emphasis should be focused on specialised intravenous therapy teams and the use of strict protocols for insertion and care of central lines.
Out of 14,841 women who were serologically examined for syphilis at the antenatal booking clinic, University Hospital, Kuala Lumpur in Malaysia, 1.78% were VDRL positive and 1.05% TPHA positive with significant differences between the Malays, Indians and Chinese. These rates are higher than published series and were attributed to childhood yaws infection among the Malays. As differentiation between yaws and syphilitic infection in the clinic is difficult, all TPHA-reactive women were treated as for syphilis. Congenital syphilis was not diagnosed in those women who had been effectively treated before delivery.
A total of 350 strains of group B streptococci (308 from adults and 42 from neonates) were serotyped. The majority of the isolates from adult patients were from the genito-urinary tract and most of the neonatal isolates were from babies less than 10 days old. Serotype III was the predominant type among all groups of patients and accounted for 50.9% of all serotypes. The second and third most frequently occurring serotypes were II and Ic respectively. Together with type III they made up 87% of the isolates.
In the University Hospital, Kuala Lumpur, from 1984 to 1990, 184 patients with acute conjunctivitis were examined for chlamydial infection by direct immunofluorescence. Overall, 52 (28.3%) were found to be positive for chlamydial antigen. There was no significant difference in the detection rate between men and women and among the 3 major ethnic groups. The detection rate was highest among sexually active adults. Epidemiological and clinical features suggest that most of the chlamydial ocular infections seen were inclusion conjunctivitis and not classical trachoma.
Study site: Eye clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
Genital discharge from patients unth. smear positive gonorrhoea was transported from the clinic to the laboratory in. Stuart's transport medium (Oxoid CM 111). Within. six hours of transit time the recovery rate of gonococci was 94%. When compared with "bedside" inoculation onto Modified Thayer Martin medium, there was no significant difference in recovery rates up to 6 hours of transportation in Stuart's transport medium, However, the rate of isolation of gonococci was significantly reduced after 20 to 30 hours of transportation. It is concluded that Stuart's transport medium is an acceptable transport medium for specimens containing gonococci when specimens reach the laboratory within 6 hours of collection.
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.
The subspecies classification of Mycobacteroides abscessus complex into M. abscessus, M. massiliense and M. bolletii requires the amplification and sequencing of multiple genes. The objective of this study was to evaluate the possibility of subspecies classification using a single PCR target. An in silico study was performed to classify 1613 strains deposited in a public database using 9 genes (partial gene sequences of hsp65, rpoB, sodA, argH, cya, glpK, gnd, and murC, and the full gene sequence of MAB_3542c). We found the housekeeping gene gnd to be able to classify the M. abscessus subspecies with high accuracy (99.94%). A single-gene PCR approach based on gnd would be a suitable replacement for the more expensive, labor-intensive and time-consuming multi-gene PCR analysis currently in use for the subspecies identification of M. abscessus.
Relative quantification is a popular analysis in gene expression studies using quantitative real-time PCR (qPCR). However, the calculation steps using the major algorithms for this analysis are rather complicated. In this study, we developed an easy-to-use spreadsheet-based method for relative quantification. The inputs from end-users are the efficiencies of both target and reference genes and the Cq values of those genes from cases and controls. This method performed normalization (with one or more reference genes), calculation of fold change of gene expression, and statistical analysis to analyze the difference between the groups in a step-by-step manner, which would allow the end-users to understand how the analysis arrived at the conclusion. Four previously published data sets with different experimental designs were used as examples. The calculated results were concordant with the results computed by the Relative Expression Software Tool (REST) 2009, a popular tool for relative quantification. Altogether, our method, which offers easy-to-understand calculation steps and does not require specialized instruments, software, or expertise to operate, would be a useful tool for students, educators, and scientists in the field of molecular biology.
Linezolid is one of the antibiotics used to treat the Mycobacteroides abscessus infection. However, linezolid-resistance mechanisms of this organism are not well understood. The objective of this study was to identify possible linezolid-resistance determinants in M. abscessus through characterization of step-wise mutants selected from a linezolid-susceptible strain, M61 (minimum inhibitory concentration [MIC]: 0.25 mg/L). Whole-genome sequencing and subsequent PCR verification of the resistant second-step mutant, A2a(1) (MIC: >256 mg/L), revealed three mutations in its genome, two of which were found in the 23S rDNA (g2244t and g2788t) and another one was found in a gene encoding the fatty-acid-CoA ligase FadD32 (c880t→H294Y). The 23S rRNA is the molecular target of linezolid and mutations in this gene are likely to contribute to resistance. Furthermore, PCR analysis revealed that the c880t mutation in the fadD32 gene first appeared in the first-step mutant, A2 (MIC: 1 mg/L). Complementation of the wild-type M61 with the pMV261 plasmid carrying the mutant fadD32 gene caused the previously sensitive M61 to develop a reduced susceptibility to linezolid (MIC: 1 mg/L). The findings of this study uncovered hitherto undescribed mechanisms of linezolid resistance in M. abscessus that may be useful for the development of novel anti-infective agents against this multidrug-resistant pathogen.
A nationwide HBV vaccination for neonates in the Expanded Programme on Immunization (EPI) was implemented in Malaysia in 1989. The objective of this study was to investigate the prevalence of HBsAg, anti-HBs and anti-HBc among the new student intakes in the Faculties of Medicine and Dentistry, University of Malaya from 2005 to 2011.
A prospective study was conducted on 510 respiratory specimens for the presence of M. tuberculosis detected by direct acid-fast bacilli (AFB) smear examination, culture in the Manual Mycobacteria Growth Indicator Tube (BBL MGIT, Becton-Dickinson) and culture on Lowenstein-Jensen (LJ) medium. From positive BBL MGIT tubes, Ziehl-Neelsen and Gram stains were performed and subcultures were put up on LJ medium. A total of 101 (19.8%) specimens were positive by the BBL MGIT, 60 (11.8%) by primary LJ medium culture, 31 (6.1%) by direct smear examination and 29 (5.7%) by all three methods. Using primary LJ culture as the gold standard, the sensitivity and specificity of the BBL MGIT were 90% and 89.6% respectively but the sensitivity of AFB smear microscopy was only 48.3%. About half (51.1%) of the BBL MGIT false positives were due to contamination by non-AFB bacteria. The remaining false positives comprised specimens that were AFB microscopy positive but LJ culture negative. Of the AFB isolates obtained on LJ primary and sub-cultures, almost all (93.3%) were identified as Mycobacterium tuberculosis complex. The mean time-to-detection was significantly shorter (p < 0.0001) for the BBL MGIT than for LJ culture. For the former, positive results were available within 14 days for both AFB smear-positive and AFB smear-negative specimens. On the average, positive results were obtained 1.8 days earlier for direct AFB smear-positive samples than for AFB smear-negative samples. On the other hand, positive growth on LJ medium appeared after at least 33 days of incubation. These findings suggest that the BBL MGIT system will be a suitable alternative to LJ culture for the routine diagnosis of pulmonary tuberculosis, but a combination of liquid and solid cultures is still required for the highest diagnostic accuracy.
A 59-year-old post-menopausal lady who had returned from a pilgrimage to Mecca about a month earlier presented with a three days' history of profuse vaginal discharge. Neissseria meningitidis was isolated from high vaginal swab specimens taken from her on 2 occasions, five days apart. Her symptoms disappeared without treatment after two weeks. We conclude that although the organism may have been a colonizer, it is possible that it was responsible for the self-limiting genital infection in this patient.
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.
Three building complexes in Kuala Lumpur were surveyed for the presence of legionellae in cooling towers. The organisms were grown from 12 out of 46 samples of water collected from 30 towers. L. pneumophila serogroups 1 and 7 were the commonest serogroups isolated. None belonged to the Pontiac subgroup of L. pneumophila serogroup 1.