The contribution of fine needle aspiration biopsy in the diagnosis of Mycobacterial Lymphadenopathy with particular reference to children

Wright, Colleen Anne (Stellenbosch : University of Stellenbosch, 2009-12)

Thesis

ENGLISH ABSTRACT: Expediting a diagnosis of tuberculosis in children, particularly those who are immunocompromised due to HIV/AIDS, is essential, as they are vulnerable to develop severe forms of disease due to their immature or compromised immune systems. A significant percentage of children (8 to 10%) with TB have TB lymphadenitis, in isolation, or in combination with other disease manifestations. Fine needle aspiration biopsy (FNAB) is a simple and minimally invasive procedure well tolerated by children. It may be performed as an outpatient procedure by clinicians as well as nurses, and excellent results can be achieved with training in the correct procedure. The aim of this dissertation was to demonstrate that FNAB may contribute significantly to the diagnosis of mycobacterial lymphadenitis, with particular reference to children TB suspects. We first established that TB lymphadenitis is a common clinical problem in children in TB endemic areas and that FNAB is an efficient simple and effective diagnostic modality in children with peripheral lymphadenopathy. We then proceeded to document the diagnostic yield and time to diagnosis of FNAB compared to conventional laboratory specimens collected in children. We investigated the value of additional diagnostic modalities such as autofluorescence in improving the ability of cytology to make a definitive diagnosis of mycobacterial infection based on cytomorphology and identification of the organism. In countries where organisms such as Mycobacterium bovis BCG and nontuberculous mycobacteria are prevalent, culture with subsequent speciation is essential. The amount of material harvested during FNAB is minuscule, and requires immediate bedside inoculation for optimal yields. We developed an inexpensive and effective transport medium to facilitate mycobacterial culture from FNAB, even if this is collected at an outside facility. It is ideally suited for use in clinics and rural hospitals as it is stable at room temperature, maintains viability of the organism for seven days, and the closed lid format reduces contamination. Mycobacterial culture even using liquid-based media, takes up to 6 weeks, and this delay is unacceptable particularly in children. We developed a Nucleic Acid Amplification Technique (NAAT) using High Resolution Melt Analysis and applied this novel technique to FNAB specimens submitted in transport medium. Although sensitivity remained suboptimal, the technique is highly specific, simple and rapid. Its use could be incorporated into routine microbiology laboratories, to assist with rapid diagnosis while cultures are pending. We collected a solid body of evidence, which will promote the use of FNAB in suspected mycobacterial lymphadenopathy, particularly in children in resource-limited countries. The utilisation of the diagnostic methods identified will expedite speciation and allow early and appropriate initiation of therapy. This is in keeping with Millennium Development Goal 6: to combat TB by early detection of new cases and effective treatment.

AFRIKAANSE OPSOMMING: Kinders met tuberkulose (TB), en veral diegene met gekompromiteerde immuniteit as gevolg van MIV/VIGS, het ‘n verhoogde neiging om ernstige siektebeelde te ontwikkel vanweë hul onvolwasse of gekompromiteerde immuunsisteme. ‘n Spoedige diagnose van TB in kinders is dus noodsaaklik. ‘n Betekenisvolle persentasie van kinders (8 tot 10%) met TB het TB limfadenitis met of sonder meegaande ander siekteverskynsels. Fynnaaldaspirasiebiopsie (FNAB) is ‘n eenvoudige en minimale indringende prosedure wat geredelik deur kinders aanvaar word. Geneeshere en verpleegkundiges wie toepaslike opleiding in die uitvoering van FNAB ontvang het, kan die prosedure op buitepasiënte uitvoer en uitstekende resultate behaal. Die doel van hierdie studie was om aan te toon dat FNAB betekenisvol kan bydra tot die diagnose van mikobakteriële limfadenitis in veral kinders met vermoedelike TB. Daar was eerstens bevestig dat TB limfadenitis ‘n algemene kliniese probleem is in kinders in TB endemiese areas en dat FNAB ‘n doeltreffende, eenvoudige en effektiewe diagnostiese modaliteit is in kinders met perifere limfadenopatie. Vervolgens was FNAB se diagnostiese opbrengs en die tydsverloop tot diagnose vergelyk met dié van konvensionele laboratoriummonsters wat in kinders verkry word. Die bydrae van verdere diagnostiese modaliteite soos outofluoressensie tot ‘n verbetering in sitologie se rol in die diagnose van mikobakteriële infeksie, soos gebaseer op sitomorfologie en identifisering van organismes, is ondersoek. In lande waar organismes soos Mycobacterium bovis BCG en nie-tuberkuleuse mikobakterië heersend is, is kultuur en spesiebepaling noodsaaklik. Die hoeveelheid materiaal wat met FNAB verkry word is baie min en vereis onmiddellike okulasie vir die beste resultate. Tydens hierdie studie is ‘n goedkoop en effektiewe vervoermedium ontwikkel om mikobakteriële kultuur van FNAB verkreë monsters te fasiliteer, selfs al is die monster vanaf ‘n buite fasiliteit bekom. Die vervoermedium is baie geskik vir gebruik in klinieke en plattelandse hospitale. Dit is stabiel by kamertemperatuur, handhaaf lewensvatbaarheid van organismes vir sewe dae, en die geslote dekselformaat verminder kontaminasie. Mikobakteriële kultuur neem tot ses weke, selfs met die gebruik van vloeistofgebaseerde mediums. Sodanige vertraging in die diagnose is veral in kinders onaanvaarbaar. Tydens hierdie studie is ‘n Nukleïnsuur Amplifikasietegniek ontwikkel deur die aanwending van Hoë Resolusie Smeltanalise en is hierdie nuwe tegniek toegepas op FNAB verkreë monsters wat in die vermelde vervoermedium versamel was. Alhoewel sensitiwiteit nie optimaal was nie, is die tegniek baie spesifiek, eenvoudig en vinnig. Dit kan in roetine mikrobiologie laboratoriums gebruik word om vinnige diagnose te bewerkstellig terwyl daar gewag word vir die kultuur se resultaat. Hierdie studie bied omvattende bewys ter ondersteuning van die gebruik van FNAB in veral kinders met vermoedelike mikobakteriële limfadenopatie in lande met beperkte hulpbronne. Die toepassing van die diagnostiese metodes wat in hierdie studie identifiseer is sal spesiebepaling bespoedig en vroegtydige en toepaslike behandeling verseker. Dit stem ooreen met Millennium Ontwikkelingsdoelwit 6: om TB te beveg deur vroeë opsporing van nuwe gevalle en effektiewe behandeling.

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