Browsing by Author "Wijesooriya, W. R. P. L. I."

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PATHOGEN DISTRIBUTION, MOLECULAR TYPING, AND DETECTION OF GENETIC MUTATION FOR MACROLIDE RESISTANCE OF MYCOPLASMA PNEUMONIAE IN EXACERBATIONS OF ASTHMA IN CHILDREN FROM A TERTIARY CARE HOSPITAL IN SRI LANKA
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka., 2024) Wijesooriya, W. R. P. L. I.
Childhood asthma is a disease with a substantial burden, mainly due to its exacerbation caused by a range of non-infective or infective causes. Although bacteria play a minor role in exacerbations of asthma (EOA), antibiotics are widely prescribed. The lack of local data on bacterial aetiology in EOA drives antibiotic misuse/abuse. Although Mycoplasma pneumoniae has been the primary target for macrolide prescriptions in EOA, identifying it as a causative agent, detecting its macrolide resistance (MR), or genetic characterisation has not been investigated in Sri Lanka. The role of viral or typical bacterial infections as a cause of EOA has also not been investigated in Sri Lanka. This research aimed to determine the infective aetiology of EOA with a particular focus on M. pneumoniae, including its detection, MR analysis and genetic characterisation. A case-control study was conducted in the paediatric units of Colombo North Teaching Hospital, Sri Lanka, involving two groups of children aged five to fifteen years: children with EOA and children with stable asthma (SA) (100 in each group). Demographic and clinical data were obtained via interviewer-administered questionnaires. Sputum/throat swabs were tested for M. pneumoniae by real-time PCR, MR by conventional PCR and sequencing to identify mutations in 23S rRNA gene and genetic characterisation by multi-locus sequence typing (MLST) for eight housekeeping genes (ppa, pgm, gyrB, gmk, glyA, atpA, arcC and adk). Respiratory samples were tested for viral pathogens by direct immunofluorescence test and bacteria by routine culture. M. pneumoniae was detected in 1% (1/100) of patients in the EOA group, with none in the SA group. The isolated strain was macrolide-sensitive, according to MLST. It was sequence type 14 (ST14). Adenovirus was the most common virus detected (9/100). There was no significant difference in the detection of common bacterial pathogens between the two groups. There was little evidence of bacterial infections causing EOA based on haematological, radiological, or microbiological tests. However, 66% (66/100) of children with EOA had been prescribed antibiotics, and 39% (39/100) had received macrolides during management. This study showed that pathogen screening provides an important and essential diagnostic approach to guide appropriate antibiotic use to minimize antibiotic resistance.
Studies on Mycoplasma pneumoniae infections among patients with respiratory illness in Sri Lanka
(University of Kelaniya, 2007) Wijesooriya, W. R. P. L. I.
Mycoplasmas represent the smallest self-replicating organisms known on the planet. Mycoplasma pneumoniae is the most important human mycoplasma pathogen causing a range of respiratory tract infections including pneumonia. M. pneumoniae causes 50% of primary atypical pneumonia, of primary atypical pneumonia contributing to 15-20% of community acquired pneumonia (CAP).. Apart from pulmonary involvement, it is associated with a range of extra pulmonary manifestations namely; encephalitis, cerebellar syndrome, aseptic meningitis, erythematous / maculopapular rashes, arthralgias, polyarthropathies, myocarditis, pancreatitis, haemolytic anaemia, glomerulonephritis, conjunctivitis etc. As M. pneumoniae does not have a cell wall like bacteria, the conventional treatment (e.g. penicillins) for CAP is not effective. Hence there is a need for prompt and correct diagnosis for effective treatment. As the diagnosis relies on laboratory tests, these may take time. Therefore empirical therapy that is guided by the prevalence data of the particular locality may facilitate treatment. This study was carried out at the North Colombo Teaching Hospital, Ragama and the chest hospital, Welisara during the period from September 2003 to August 2004. The study was to determine the prevalence of M. pneumoniae infection among patients with respiratory tract infections - particularly in three patient groups (pneumonia, acute bronchitis, sore throat) and a control group. Each group consisted of 200 patients. Paired serum samples were obtained from each group for serology antibody tests using M. pneumoniae specific Enzyme-Linked Immunosorbent Assay (ELISA) (isotype specific) and Cold Agglutinin Test (CAT). Respiratory samples from each individual at first sampling were used for detection of M. pneumoniae DNA. Serologically confirmed cases of M. pneumoniae with age and gender were matched with serologically negative group of patients selected for M. pneumoniae DNA PCR. CAT was performed only for patients with pneumonia at acute stage. The prevalence of M. pneumoniae infection by antibody test was 15.5%, 6.6% and 1.2% in patients with pneumonia, acute bronchitis and sore throat respectively. M. pneumoniae DNA was detected in 52% of serology confirmed cases and 15 % of serology negative cases. CAT was positive in 20% of serology positive patients and 20% of serology negative patients. Isotype specific antibody assays are helpful for extended diagnosis. Detection of specific IgM in one sample enabled diagnosis but paired sera was necessary to demonstrate seroconversion when testing for specific IgG. In the study, IgA was shown to be a better indicator of severe infection as this antibody class was observed only in patients with pneumonia. However, specific IgA detection showed low sensitivity. PCR was available to diagnose 15% (4/26) serologically negative patients but it missed serologically positive patients. The combination of antibody serology and PCR detection for M. pneumoniae DNA enabled effective laboratory diagnosis in the clinical setting. The CAT was found to offer no distinct advantage and was no longer recommended even as a bed side screening test due to its poor sensitivity and specificity. In the treatment of pneumonia, the decision on empirical antibiotic regime needs to consider the prevalence rate (15.5%) of most common atypical bacterium M. pneumoniae in Sri Lanka.