Seroprevalence of diphtheria toxoid IgG antibodies in the Malaysian population.

BACKGROUND: Despite high childhood immunization coverage, sporadic cases of diphtheria have been reported in Malaysia in recent years. This study aims to evaluate the seroprevalence of diphtheria among the Malaysian population. METHODS: A total of 3317 respondents age 2 years old to 60 years old were recruited in this study from August to November 2017. Enzyme-linked immunosorbent assay (ELISA) was used to measure the level of IgG antibody against the toxoid of C. diphtheriae in the blood samples of respondents. We classified respondent antibody levels based on WHO definition, as protective (≥0.1 IU/mL) and susceptible (< 0.1 IU/mL) to C. diphtheriae infection. RESULTS: Among the 3317 respondents, 57% were susceptible (38.1% of children and 65.4% of adults) and 43% (61.9% of children and 34.6% of adults) had protective antibody levels against diphtheria. The mean antibody level peaked among individuals aged 1-2 years old (0.59 IU/mL) and 6-7 years old (0.64 IU/mL) but generally decreased with age, falling below 0.1 IU/mL at around 4-6 years old and after age 20 years old. There was a significant association between age [Children: χ2 = 43.22(df = 2),p < 0.001)], gender [Adults: χ2 = 5.58(df = 1),p = 0.018] and ethnicity [Adults: χ2 = 21.49(df = 5),p = 0.001] with diphtheria toxoid IgG antibody level. CONCLUSIONS: About 57% of the Malaysian population have inadequate immunity against diphtheria infection. This is apparently due to waning immunity following childhood vaccination without repeated booster vaccination in adults. Children at age 5-6 years old are particularly vulnerable to diphtheria infection. The booster vaccination dose normally given at 7 years should be given earlier, and an additional booster dose is recommended for high-risk adults.

Association of CD58 polymorphism and multiple sclerosis in Malaysia: a pilot study.

BACKGROUND: Multiple sclerosis is an immune mediated disease targeting the central nervous system. Association of non-human leukocyte antigen gene, CD58, with multiple sclerosis has been reported in several populations but is unclear among Southeast Asians. This pilot study was conducted to explore the association between CD58 polymorphism and multiple sclerosis among the Malay population in Malaysia. METHODS: Blood samples were collected from 27 multiple sclerosis patients, and compared with 58 age- and gender matched healthy individuals. All patients were tested negative for anti-aquaporin 4. DNA was extracted from the blood and genotyped for 3 single nucleotide polymorphisms rs12044852, rs2300747 and rs1335532 of gene CD58 by real-time PCR. RESULTS: The majority of multiple sclerosis patients were female (85.2%). The general mean age of onset was 30.5 years. Genotyping results showed that frequencies of the alleles were between 40 and 50% for MS patients and healthy individuals. Association (allelic model) between multiple sclerosis and CD58 gene polymorphism alleles rs12044852 (p = 0.410), rs2300747 (p = 0.881) and rs1335532 (p = 0.407) were indistinct. CONCLUSIONS: The impact of the CD58 gene polymorphism was not prominent in this pilot study, implying that genetic composition contributing to multiple sclerosis may be different between different populations, thus results in a heterogeneity of disease manifestation and distribution.

Genotypic variations of virulent genes in Enterococcus faecium and Enterococcus faecalis isolated from three hospitals in Malaysia.

BACKGROUND: The genus Enterococcus is of increasing significance as a cause of nosocomial infections, and this trend is exacerbated by the development of antibiotic resistance. OBJECTIVES: The aim of the present study was to estimate the potential virulence factors in enterococci and to ascertain their prevalence in Malaysian hospitals. MATERIAL AND METHODS: The study comprised 222 enterococcal strains isolated from blood, urine, exudates, sputum, stool and body fluid. These strains were collected from patients staying in three referral hospitals in Malaysia. All isolates were identified to the species level, and their MIC of vancomycin was determined using E test strips. Specific primers were designed for detection of the five potential virulence genes (gelE, PAI, esp, ace, and sprE) by PCR assay. RESULTS: Different patterns and frequency of virulence determinants were found for the E. faecalis and E. faecium isolates. E. faecalis isolates had more virulence determinants than E. faecium isolates. Clinical enterococcal isolates were found to possess more virulence determinants than enterococci isolated from faecal samples. The esp gene is significantly more common (p = 0.049) in vancomycin-resistant strains (85.7%) than in vancomycin-sensitive strains (44.2%). All of the vancomycin-resistant isolates were isolated from faecal samples. None of the classical virulence factors were found in 11% of enterococcal isolates, while all five virulence genes were found in 21% of enterococcal isolates. CONCLUSIONS: All the virulence genes considered in this study were important in the pathogenesis of enterococcal infections and further studies including more virulence genes and epidemiological data will be necessary in order to analyze the association and role of virulence genes in the pathogencity of enterococci.

Specific detection of fungal pathogens by 18S rRNA gene PCR in microbial keratitis.

BACKGROUND: The sensitivity and specificity of 18S rRNA polymerase chain reaction (PCR) in the detection of fungal aetiology of microbial keratitis was determined in thirty patients with clinical diagnosis of microbial keratitis. METHODS: Corneal scrapings from patients were used for Gram stain, culture and PCR analysis. PCR was performed with primer pairs targeted to the 18S rRNA gene. The result of the PCR was compared with conventional culture and Gram staining method. The PCR positive samples were identified by DNA sequencing of the internal transcribed spacer (ITS) region of the rRNA gene. Main outcome measures were sensitivity and specificity of PCR in the detection of fungus in corneal keratitis. RESULTS: Combination of microscopy and culture gave a positive result in 11 of 30 samples of microbial keratitis. PCR detected 10 of 11 samples that were positive by conventional method. One of the 19 samples that was negative by conventional method was positive by PCR. Statistical analysis revealed that the PCR to have a sensitivity of 90.9% and specificity of 94.7% in the detection of a fungal aetiology in microbial keratitis. CONCLUSION: PCR is a rapid, sensitive and useful method to detect fungal aetiology in microbial keratitis.

Enzyme-linked amperometric electrochemical genosensor assay for the detection of PCR amplicons on a streptavidin-treated screen-printed carbon electrode.

A general purpose enzyme-based amperometric electrochemical genosensor assay was developed wherein polymerase chain reaction (PCR) amplicons labeled with both biotin and fluorescein were detected with peroxidase-conjugated antifluorescein antibody on a screen-printed carbon electrode (SPCE). As a proof of principle, the response selectivity of the genosensor was evaluated using PCR amplicons derived from lolB gene of Vibrio cholerae. Factors affecting immobilization, hybridization, and nonspecific binding were optimized to maximize sensitivity and reduce assay time. On the basis of the background amperometry signals obtained from nonspecific organisms and positive signals obtained from known V. cholerae, a threshold point of 4.20 microA signal was determined as positive. Under the optimum conditions, the limit of detection (LOD) of the assay was 10 CFU/mL of V. cholerae. The overall precision of this assay was good, with the coefficient of variation (CV) being 3.7% using SPCE and intermittent pulse amperometry (IPA) as an electrochemical technique. The assay is sensitive, safe, and cost-effective when compared to conventional agarose gel electrophoresis, real-time PCR, and other enzyme-linked assays for the detection of PCR amplicons. Furthermore, the use of a hand-held portable reader makes it suitable for use in the field.