Syahrina Rahim [Supervisor]Naidatul Ain Binti Zahaimi2024-09-182024-09-182024-09Naidatul Ain Binti Zahaimi.(2024). A Study of Post-Mortem Microbiology And Clinicopathological Features in Sudden Unexpected Death of Infant and Childhood (Sudi/Sudc). [Master’s thesis, Universiti Sains Islam Malaysia]USIM Research Repository.https://oarep.usim.edu.my/handle/123456789/22871Matric: 3201422 (FPSK)-Restricted until Sept 2027Post-mortem microbiology (PMM) has been part of autopsy protocol for investigating of Sudden Unexpected Death of Infant and Childhood (SUDI and SUDC) to detect unexpected infections causing sudden death. Despite identifying pathogenic isolates, the interpretation is challenging due to multiple factors; often leaving the cause of death unexplained. In addition, there are substantial gaps in identifying risk factors and understanding the pathogenesis. To date, this is the first cross-sectional study on Malaysian SUDI and SUDC focusing on PMM, autopsy findings and virulence of bacterial isolates. This study aimed to describe the associations between post-mortem bacterial isolates and clinicopathological features in SUDI and SUDC in Klang Valley. Specifically, it focused on detailing the clinicopathological features and bacterial isolates, identifying types of bacteria, sampling sites, and growth culture outcomes, as well as determining the associations and virulence genes of these bacterial isolates. Autopsy data of all <5-year-old SUDI and SUDC cases performed in two tertiary centres in Klang Valley from 2018-2022 were extracted and analysed. Archived bacterial isolates were revived on culture media, subjected to phenotypic observation, molecular confirmation, and subsequent whole genome sequencing for virulence genes identification. A total of 118 SUDI and SUDC cases were identified, with majority of deaths occurring in <1-year-old 95/118 (80.5%) (p<0.05). Out of this total, 106 (89.8%) autopsies were conducted. PMM samplings were performed in 94 (88.7%) of these autopsies. A total of 217 PMM samplings were able to isolate microbial cultures in 92 (97.9%) of these 94 cases, identifying 179 (82.5%) organisms. The commonest positive sampling sites were from lower respiratory tract 99/217 (45.6%) and hemoculture (blood/spleen/liver) 72/217 (33.2%). Bacterial isolates account for the largest proportion of isolates at 163/179 (91.1%) with Klebsiella spp. 34/163 (20.9%), S. aureus 22/163 (13.5%) and E. coli 20/163 (12.3%) predominating. Klebsiella species with tissue haemorrhage and inflammation was associated with age group <1-year-old (p<0.001). PMM samplings detected unexpected infections contributory to death in 81/92 (88.0%) with bacterial aetiologies in 75/81 (92.6%), which contributes significantly to <1-year-old death (p<0.05). Virulence genes identified were related to adherence, exoenzyme, immune modulation, effector delivery system, exotoxin, biofilm, nutritional/metabolic factor, stress survival, antimicrobial activity/competitive advantage, regulation and invasion. Antimicrobial resistance genes observed were related to macrolide-lincosamide-streptogramin (MLS), rifampin, elfamycin, fluoroquinolones, fosfomycin, aminocoumarins, sulfaanomide and betalactams. Klebsiella pneumoniae isolates were found to have the greatest number of virulence factors, while Staphylococcus aureus and E. coli have the highest number of AMR genes amongst gram-positive (15/21, 71.4%) and negative (12/21, 57.1%) bacteria respectively. Infants <1-year-old are generally predisposed to bacterial infections due to immaturity of the immune system. However, in most cases infants do not display a noticeable infection focus. Hence, PMM remains to have critical value in SUDI/SUDC investigations. Identification of infective causes warrants a public health intervention so that further risk assessment can be done in the community to identify the source of the pathogen and provide insight into the epidemiology and socio-demographic factors. This may help in recognizing possible associated risk factors and thus, preventing further deaths.en-USPost-mortem microbiology (PMM)Sudden deathSudden Unexpected Death of Infant and ChildhoodMalaysianPathologySamplingtext::thesis::master thesis