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Infection and immunology
Published in Jagdish M. Gupta, John Beveridge, MCQs in Paediatrics, 2020
Jagdish M. Gupta, John Beveridge
5.28. Immunoglobulin G (IgG)does not cross the placenta.is the main immunoglobulin of external secretions.is secreted by macrophages.is the predominant serum immunoglobulin.provides immunity against Mycobacterium tuberculosis.
BCG and Other Vaccines
Published in Lloyd N. Friedman, Martin Dedicoat, Peter D. O. Davies, Clinical Tuberculosis, 2020
Vaccination with BCG may confer protection against non-tuberculous mycobacterial species due to cross-reactivity with conserved, often immunodominant, antigens.58 The estimates of protective efficacy against leprosy, caused by Mycobacterium leprae, vary from 20% to 90%.45,59 Although one meta-analysis determined an overall BCG-vaccine protective effect of 41% (95% CI 16–66) for trials and 60% (95% CI 51–70) for observational studies,60 another analysis reported just 26% (95% CI 14–37) and suggested that protection had been overestimated in observational studies.61 Cross-protection of BCG against Buruli ulcer disease has been reported in some studies62,63 but not in others.64,65 Murine studies have demonstrated a protective effect of BCG against infection with Mycobacterium avium and Mycobacterium kansasii.66 A study of neonates in the Czech Republic found that M. avium intracellulare complex-associated lymphadenitis was lower in BCG-vaccinated compared with unvaccinated children.38
Infections
Published in C. Simon Herrington, Muir's Textbook of Pathology, 2020
The main diagnostic methods are direct examination of sputum, tissue, CSF, and so on for AFBs and culture of suspected material (culture has higher sensitivity and enables identification of which particular Mycobacterium sp.). Tissue is obtained by knife biopsy, fine-needle aspiration of peripheral nodes, and CT-guided biopsy of, e.g. deep lymph nodes. It is essential that such material be submitted for culture as well as histology. Increasingly, polymerase chain reaction (PCR) technology is used for rapid sensitive diagnosis on fresh tissue material and, furthermore, for the rapid identification of sensitivity to rifampicin, the main antituberculosis drug.
Chapter 9: Pediatric tuberculosis
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2022
Rachel Dwilow, Charles Hui, Fatima Kakkar, Ian Kitai
Pediatric TB disease, when compared with adult TB disease, is less likely to be microbiologically confirmed, due to its paucibacillary nature (less than 40% are culture positive); therefore, a negative microbiological test result should not be used to exclude TB disease.21 Mycobacterial confirmation of the diagnosis should be attempted by collecting multiple specimens. This is particularly important when (1) an isolate from a source case is not available or there are multiple possible sources; (2) the source case has drug-resistant TB; (3) the child is immunocompromised; or (4) the child has extra-pulmonary disease.22,23 In cases where pulmonary disease is minimal (ie, hilar adenopathy only), all other diagnoses have been excluded and only one drug-sensitive potential source case has been identified, then cultures are sometimes omitted and the source case sensitivities are used to guide management.
The Relationship between COVID-19 Severity and Bacillus Calmette-Guérin (BCG)/ Mycobacterium tuberculosis exposure history in healthcare workers: a multi-center study
Published in Pathogens and Global Health, 2021
Serife Torun, Sevket Ozkaya, Nazan Şen, Fikret Kanat, Irem Karaman, Sebnem Yosunkaya, Ozlem Sengoren Dikis, Ali Asan, Selma Aydogan Eroglu, Sefa Semih Atal, Omer Ayten, Nimet Aksel, Hilal Ermiş, Neslihan Özçelik, Meryem Demirelli, Iskender Kara, Sua Sümer, Kamile Marakoğlu, Fatih Üzer, Yasin Uyar, Tuba Çiçek, Zuhal E Ünsal, Husamettin Vatansev, Berna Botan Yildirim, Tuba Kuruoğlu, Aynur Atilla, Yasemin Ersoy, Bahar Kandemir, Yasemin Durduran, Fatma Goksin Cihan, Nur Demirbaş, Fatma Yıldırım, Dursun Tatar, M Sule Akcay
Increased exposure to an infectious tuberculosis patient might develop neither active infection nor latent tuberculosis infection, also known as early clearance (resistance to infection by innate protection). Several immune mechanisms that functionally reprogram innate immunity such as unconventional T-cell responses, higher levels of T helper type 17 cytokines which are involved in the orchestration of neutrophil responses have been implicated in the early clearers [19]. Kooken et al.suggested that trained immunity can be responsible for eliminating the mycobacteria and inducing early clearance. Likewise, we hypothesized that different parameters that increase the exposure to M. tuberculosis bacillus such as presence of tuberculosis unit in the hospital, direct care and contact to infectious tuberculosis patients might have an impact on functional programming of innate immunity into trained immunity through early clearance mechanisms.
Integrating childhood TB: applying the care delivery value chain to improve pediatric HIV/TB services in Togo, West Africa
Published in AIDS Care, 2020
Melanie Dubois, Elissa Z. Faro, Diana S. Lee, Venance Katin, Komlan Kenkou, Kevin P. Fiori
Pediatric TB has historically been neglected from a public health standpoint for various reasons. One reason is that children are less contagious than adults with regards to disease transmission; this is largely due to the paucibacillary nature of childhood TB, as there is less bacteria in the sputum to spread to others (Starke, 2003). However, children have a significant burden of disease and different disease presentation compared to adults, as young children are more prone to extra-pulmonary and life-threatening cases of TB (Starke, 2003). Pediatric TB is also particularly challenging to diagnose as it is difficult to detect bacteria in sputum, often leading to delay in diagnosis or failure to diagnose. This failure in diagnosis is concerning, as it suggests an unrecognized global burden of childhood morbidity and mortality due to undiagnosed tuberculosis (Jenkins, 2017). Sputum smear microscopy is often the only diagnostic test available in many settings worldwide, but positive findings are noted for <10–15% of children with probable TB (Marais, 2007). Other diagnostic modalities, including gastric aspirates and induced sputum samples, are increasingly being used in children to improve detection of TB, particularly for children under age five. Mycobacterial culture remains the most definitive diagnostic test, but is not available in all settings (Ballif, 2015). In addition to these microbiological tests, contact tracing is particularly important for pediatric TB, as often pediatric cases can be connected to a recent exposure to an adult case of TB (Starke, 2003).