A morphological assessment of the health status of a cadaver population at the Faculty of Health Sciences, Stellenbosch University, with special reference to tuberculosis (TB) Lesion distribution

Geldenhuys, Elsje-Marie (2014-12)

Thesis (PhD)--Stellenbosch University, 2014.

Thesis

ENGLISH ABSTRACT: Tuberculosis (TB) is a chronic pulmonary infection characterized by granulomatous inflammation, caseating necrosis and a propensity to develop fibrosis and cavitations. Pulmonary TB (PTB) lesions may develop in a variety of ways and can be grouped into primary, secondary, progressive primary and miliary TB based on their pathogenesis and morphological appearance. The Western Cape Province, South Africa, has a high TB burden with increasing TB notification rates. At Stellenbosch University (SU), approximately 90% of cadavers used for medical dissections come from impoverished communities where TB is a major health problem in terms of morbidity. The aim of the present study was to assess the health status of a cadaver population (n=127) at the Faculty of Medicine and Health Sciences (FMHS), SU, with special reference to TB lesion distribution and prevalence. For this study, full-body digital X-rays of 127 cadavers (87 males; 40 females; average age, 47.1 years) were obtained with the Lodox® Statscan® Imaging System after embalming and prior to dissection. A complete pathology report of six organ systems including the skeletal system was used in combination with histological examination, molecular analysis and radiological findings to investigate the prevalence and association between TB and systemic pathology. Samples for histological purposes were removed from organs with pathology lesions. For molecular studies, five different nucleic acid extraction methods were used to extract DNA from the formalin-fixed paraffin-embedded cadaver samples. Pulmonary samples were subjected to a line probe assay (LPA) and polymerase chain reactions (PCR) to determine mycobacterial genotypic distribution. Two independent radiologists examined the chest X-rays and their findings were compared with the pulmonary findings. PTB was a common finding in the cadaver population (76.4%) with males more commonly affected. A female predilection was observed for extrapulmonary TB. Statistically, TB was associated with pulmonary pathology, including pneumonia and bronchiectasis. Systemic pathology commonly encountered in the present study included neoplasms, coronary artery disease, colonic diverticula, hepatic triaditis, cirrhosis, glomerulosclerosis, pyelonephritis and a variety of healed maxillofacial and appendicular skeletal fractures. Extracted nucleic acid concentrations, as determined with the NanoDrop® spectrophotometer, ranged between 10ng/μl and 1000ng/μl. The standard salting-out method was found to be the most cost-effective and therefore the preferred method for nucleic acid extraction. The HAIN® MTBDRplus® kit was effective in determining the presence of mycobacterial species belonging to the Mycobacterium tuberculosis complex (MTBC). The sensitivity to first-line drugs could not be determined as a result of DNA degradation. Spoligotyping was unsuccessful, as incomplete and unidentifiable hybridization of the 43 spacers occurred. The RD105 and MUB02/RD105 PCR results were non-reproducible and non-specific. Pulmonary cavitation and pleural thickening were the only findings that were positively correlated with the radiological findings (p<0.05). To our knowledge, this is the first study to extensively investigate TB and systemic pathology including histopathology, molecular techniques and postmortem radiology in cadavers from low socio-economic backgrounds from a high TB burden area. This study therefore provides a more complete and thorough understanding of the prevalence, distribution and morphology of TB lesions as well as the association between TB and systemic pathology.

AFRIKAANSE OPSOMMING: Tuberkulose (TB) is a kroniese, pulmonêre infeksie gekenmerk deur granulomateuse ontsteking, verkasende nekrose en ’n neiging om fibrose en kavitasies te ontwikkel. Pulmonêre TB (PTB) letsels kan op verskeie wyses ontwikkel en kan, gebaseer op patogenese en morfologiese voorkoms, geklassifiseer word as primêre, sekondêre, progressiewe primêre of miliêre TB. Die Wes-Kaap provinsie, Suid-Afrika, het ’n hoë TB las met toenemende TB aanmeldingskoerse. Ongeveer 90% van die kadawers wat by die Universiteit Stellenbosch (US) gebruik word vir mediese disseksies kom van verarmde gemeenskappe waar TB ’n groot gesondheidsprobleem is in terme van die siektesyfer. Die doel van hierdie studie was om die gesondheidstoestand te bepaal van ’n kadawerpopulasie (n=127) by die Fakulteit Geneeskunde en Gesondheidswetenskappe (FGG), US, met spesifieke verwysing na die verspreiding en voorkoms van TB letsels. Digitale X-strale van die hele liggaam van 127 kadawers (87 manlik; 40 vroulik; gemiddelde ouderdom, 47.1 jaar) na balseming en voor disseksie is met behulp van die Lodox® Statscan® Imaging System bekom. ’n Volledige patologie-verslag van ses orgaanstelsels, die skeletstelsel ingesluit, is in kombinasie met histologiese ondersoeke, molekulêre ontleding en radiologiese bevindinge gebruik om die voorkoms van en assosiasie tussen TB en sistemiese patologie te ondersoek. Monsters vir histologiese studie is van organe met patologiese letsels geneem. Vir molekulêre studies is vyf verskillende nukleïensuur ekstraksie-metodes gebruik om DNS uit die formalien-gefikseerde paraffien-ingebed kadawermonsters te ekstraheer. Pulmonêre monsters is onderwerp aan ’n lyn-ondersoek-toets (“line probe assay”) en polimerase-kettingreaksies (PKR) om mikobakteriële genotipiese verspreiding te bepaal. Twee onafhanklike radioloë het die bors X-strale ondersoek en hulle bevindinge is vergelyk met die pulmonêre bevindinge. PTB is ’n algemene bevinding in die kadawerpopulasie (76.4%) met mans wat meer dikwels geaffekteer is. ’n Vroulike voorkeur vir ekstrapulmonêre TB is waargeneem. TB is statisties geassosieër met pulmonêre patologie, longontsteking en brongiëktase. Sistemiese patologie wat algemeen gevind is in die huidige studie sluit in neoplasmas, koronêre hartsiekte, kolon divertikula, lewer triaditis, sirrose, glomerulosklerose, piëlonefritis en ’n verskeidenheid geneesde maksillofasiale en appendikulêre skeletale frakture. Geëkstraheerde nukleïensuur-konsentrasies, soos bepaal met die NanoDrop® spektrofotometer, het gewissel tussen10ng/μl en 1000ng/μl. Daar is gevind dat die standaard uitsoutings-metode die mees koste-effektief en dus die voorkeur-metode nukleïensuur ekstraksie-metode was. Die HAIN® MTBDRplus® toets was effektief om die aanwesigheid van mikobakteriële spesies wat aan die Mycobacterium tuberculosis kompleks behoort, te bepaal. Sensitiwiteit vir eerste-linie middels kon nie bepaal word nie as gevolg van DNS degradasie. Spoligotipering was onsuksesvol omdat onvoltooide en onidentifiseerbare hibridisasie van die 43 merkers plaasgevind het. Die RD105 en MUB02/RD105 PCR resultate was nie-herhaalbaar en nie-spesifiek. Pulmonêre kavitasie en pleurale verdikking was die enigste bevindinge wat positief gekorreleer is met die radiologiese bevindinge (p<0.05). Na ons wete is hierdie studie die eerste een wat TB en sistemiese patologie ekstensief ondersoek en gebruik maak van histopatologie, molekulêre tegnieke en nadoodse radiologie in kadawers van lae sosio-ekonomiese agtergronde vanaf ’n area met ’n hoë TB las. Hierdie studie verskaf dus ’n meer volledige en deeglike begrip van die voorkoms, verspreiding en morfologie van TB letsels sowel as die assosiasie tussen TB en sistemiese patologie.

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