Wijesooriya, W. R. P. L. I.2025-09-082024Wijesooriya, W. R. P. L. I. (2024). 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. Doctor of Philosophy in Medical Microbiology Thesis, Faculty of Graduate Studies, University of Kelaniya, Sri Lanka.http://repository.kln.ac.lk/handle/123456789/29851Childhood 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.Exacerbation of asthmaMycoplasma pneumoniaeMacrolide resistanceMLSTAntibiotic resiThesis