Browsing by Subject "pneumonia"

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    Open Access
    Post-mortem Lodox® as a potential substitute for histologic confirmation of pneumonia in sudden infant death investigation
    (2024) Cook, Tracy Leanne; Taylor, Laura Dawn
    Background: Lodox®, low dose digital x-rays, may be used as a cost-effective screening tool in developing countries for the post-mortem diagnosis of pneumonia in the medicolegal investigation of sudden unexpected infant death, avoiding the need to perform an internal examination. However, interpretation of the Lodox® is not standardised, and this modality has not yet been validated or tested against the recognised best standard in autopsy practice, histologic examination. Objective: This study aimed to evaluate whether interpretation of a post-mortem Lodox® scan is sufficient to diagnose pneumonia in alleged sudden infant deaths, without the need for confirmatory histology. Methods: A retrospective cross-sectional study was performed. Lodox® scans and lung histology from 100 infant decedents less than 1 year of age, admitted to Salt River Mortuary between 2011-2021, were independently interpreted according to standardised guideline by a senior forensic pathology registrar (100 cases), radiologist and anatomical pathologist (25 cases each). The data were captured in a Microsoft Excel® spreadsheet and subjected to statistical analysis. Results: Fifty-seven male infants (57%) and forty-three female infants (43%) were included in the study. The majority of infants were 1 to 5 months of age (67%) with an average age of 3.25 months and the most frequent age encountered being 2 months old. More than half of the Lodox® scans and lung histology were categorised as minor/non-specific changes. Lodox® categorisation was mostly inconsistent with histology categorisation (weighted-k: 0,14; CI: - 0,02-0,29) with a negligible relationship between the two modalities (Pearson co-efficient: 0,14 (p:0,16) and Spearman co-efficient: 0,15 (p:0,13)). A strongly positive relationship between registrar and anatomical pathologist histology categorisations was observed (Pearson co- efficient: 0,4 (p:0,05) and Spearman co-efficient: 0,42 (p:0,04)). Fair inter-rater agreement was noted between the registrar and radiologist categorisations; however, these findings displayed broad confidence intervals. (Lodox® weighted-k: 0,27; CI: - 0,09-0,59; histology weighted-k: 0,29; CI: -0,03-0,49). Moderate correlation noted between registrar and radiologist Lodox® categorisations was statistically insignificant (Pearson co-efficient: 0,35 (p:0,09) and Spearman co-efficient: 0,31 (p:0,11)). The Lodox® displayed a low sensitivity of 32% (17%, 51%) with a low positive predictive value of 42% (22%, 63%). Conversely, a high specificity of 80% (68%, 88%; p:0,21) in addition to a high negative predictive value of 72% (61%, 82%; p:0,21) was observed. Conclusion: The potential utilisation of the Lodox® scan as a substitute for histologic diagnosis of pneumonia in sudden infant death would make a vast difference in forensic practice in lower income countries, where caseloads are high and access to sophisticated imaging is limited. The small sample size in this study (n:100) did not yield statistically significant information to conclude that a relationship exists between Lodox® and histology categorisation. Nonetheless, results suggest that the diagnosis of pneumonia on Lodox® may be unreliable, resulting in failure to identify unnatural causes of death that may not be apparent on history, Lodox® and external examination, as well as compromise public health interventions and cause of death data. Further studies are required to properly evaluate post mortem Lodox® as a potential substitute for internal examination and histologic diagnosis of pneumonia in sudden infant death investigation.
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    The yield of nasopharyngeal bacteria from culture compared to polymerase chain reaction in South African children with lower respiratory tract infection
    (2022) Pillay, Vashini; Zar, Heather
    Background Lower respiratory tract infection (LRTI) is a major cause of morbidity and mortality in children under 5 years of age. Bacterial pathogens contribute significantly to this process. Culture of respiratory tract specimens is labour-intensive and slow. Polymerase chain reaction (PCR) is comparatively, a rapid, sensitive method of detecting low levels of nucleic acid for clinically relevant bacteria. This study compares the yield of bacteria obtained from culture and the FTDResp33 multiplex PCR of nasopharyngeal swabs (NPs) during LRTI episodes in children, in the Drakenstein Child Health Study. Methods At each episode of LRTI, 2 NPs were obtained, one for culture and one for PCR testing. Bacterial yields and concordance for the 5 commonest bacteria were compared using frequencies and proportions. Results From 13th August 2012 to 23rd November 2020, there were 859 episodes of LRTI in 434 children [median age 9.2 (IQR 3.8; 18.9) months; 0.2% HIV-infected]. S. pneumoniae, S. aureus, M. catarrhalis, H. influenzae and K. pneumoniae were the predominant bacteria detected by either method. Concordance between culture and PCR for S. pneumoniae, S. aureus, and K. pneumoniae was 84.9%, 89.7% and 86.3% respectively. Culture and PCR for H. influenzae had a concordance of 76.9%. The greatest discordance between culture and PCR was for the detection of M. catarrhalis (34.4%). Median bacterial loads on PCR for all 5 organisms were significantly associated with semi-quantitative culture results (p<0.001 for each). Adjusting for age and hospitalization, children on antibiotics at the time of sampling, had a reduced chance of having a positive culture (OR 0.1; 95% CI 0.1-0.4), and a reduction in PCR yield (OR 0.8; 95% CI 0.4-1.6). Conclusion: Significant concordance existed between PCR and culture for 4 of the 5 common bacteria, affirming PCR as a comparable method of testing to culture.