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Nulda Beyers

Publications and source records attributed to Nulda Beyers.

28 records · Page 2Linked to original sources
PubMed2004

Stability of polymorphic GC-rich repeat sequence-containing regions of Mycobacterium tuberculosis.

Mycobacterium tuberculosis cultures were subjected to DNA fingerprinting with IS6110- and polymorphic GC-rich sequence (PGRS)-containing probes. The PGRS banding patterns remained highly stable during multiple cultures of specimens from one disease episode (0.5% changed) and during transmission in patients with close contact (1.9% changed). Characteristic PGRS-restriction fragment length polymorphism motifs for different strain groupings may indicate distant evolutionary events leading to the differentiation of M. tuberculosis strain lineages.

Cytosine↗
PubMed2003

Patients with active tuberculosis often have different strains in the same sputum specimen.

It is generally accepted that tuberculosis results from a single infection with a single Mycobacterium tuberculosis strain. Such infections are thought to confer protective immunity against exogenous reinfection. In this study, a novel polymerase chain reaction method was developed to specifically identify M. tuberculosis strains belonging to the Beijing and non-Beijing evolutionary lineages in sputum specimens collected from tuberculosis patients resident in an epidemiologic field site in Cape Town, South Africa. The sensitivity and specificity of the polymerase chain reaction-based strain classification method were 100% (95% confidence interval, 85-100%) when compared with DNA fingerprinting and spacer oligotyping (spoligotyping). Application of this method showed that 19% of all patients were simultaneously infected with Beijing and non-Beijing strains, and 57% of patients infected with a Beijing strain were also infected with a non-Beijing strain. Multiple infections were more frequent in retreatment cases (23%) as compared with new cases (17%), but were not associated with sex, age, or smear grading. These results suggest that multiple infections are frequent, implying high reinfection rates and the absence of efficient protective immunity conferred by the initial infection. This finding could influence our understanding of the epidemiology of disease in high-incidence regions and our understanding for vaccine development.

Adult↗
PubMed2003

World TB Day 2003.

Explore the source record for details and available documents.

Antitubercular Agents↗
PubMed2002

Fine mapping of a putative tuberculosis-susceptibility locus on chromosome 15q11-13 in African families.

Host genetics plays an important role in individual susceptibility and resistance to infectious diseases, but no genes have yet been identified using genome-wide screens. Twin studies have indicated that tuberculosis susceptibility has a significant host genetic component, and several genes appear to be involved. Recently, a genome-wide linkage analysis of 136 African families identified chromosome 15q11-13 as a region with suggestive evidence of linkage, with a LOD score of 2.0. We tested 10 microsatellite markers and 5 positional candidate genes in this chromosomal region for deviation from random transmission from parents to affected offspring. The polymorphisms, lying in a region of 14 cM, were initially typed in the same 79 Gambian families used in the genome screen. A borderline significant association with a 7 bp deletion in UBE3A (P = 0.01) was found. This polymorphism was then evaluated further in a larger series of families with tuberculosis, including 44 Guinean families and 57 families from South Africa. Testing for association between the deletion and tuberculosis across all the families using the exact symmetry test further supported the association (overall P = 0.002). These fine-mapping data suggest that UBE3A or a closely flanking gene may be a tuberculosis-susceptibility locus.

Black People↗
PubMed2002

Tuberculosis in the tropics.

Tropical countries bear the brunt of the global TB burden. Young children are at high risk and suffer the most severe forms of TB; adults with pulmonary cavities are the main sources of transmission. The incidence in sub-Saharan Africa is increasing as a consequence of the HIV pandemic. Smear-negative TB, which is common in children and patients who have HIV infection, is becoming a major problem in resource-poor settings where access to mycobacterial culture and histopathology is limited. Clinical case definitions are being developed to address this problem. Short courses of rifampin-based therapy are not universally available, but access is increasing. DOTS is the main strategy that the WHO is promoting to improve TB control. This is particularly important for sputum smear-positive patients. Unfortunately, the DOTS targets set by the WHO have not yet been met. Innovative, low-cost ways of supervising therapy have been developed using family members or lay supervisors. Preventive therapy in tropical countries is limited to high-risk cases (young children and HIV-infected patients who are tuberculin skin test-positive). An improved TB vaccine would dramatically improve TB control.

Humans↗
PubMed2002

Stability of variable-number tandem repeats of mycobacterial interspersed repetitive units from 12 loci in serial isolates of Mycobacterium tuberculosis.

Variable number tandem repeats (VNTRs) of elements named mycobacterial interspersed repetitive units (MIRUs) have previously been identified in 12 minisatellite loci of the Mycobacterium tuberculosis genome. These markers allow reliable high-throughput genotyping of M. tuberculosis and represent a portable approach to global molecular epidemiology of M. tuberculosis. To assess their temporal stability, we genotyped 123 serial isolates, separated by up to 6 years and belonging to a variety of distinct IS6110 restriction fragment length polymorphism (RFLP) families, from 56 patients who had positive sputum cultures. All 12 MIRU VNTR loci were completely identical within the groups of serial isolates in 55 out of 56 groups (98.2%), although 11 pairs of isolates from the same patients with conserved MIRU VNTRs displayed slightly different IS6110 RFLP profiles. In a single case, serial isolates with an unchanged IS6110 RFLP profile showed a change in 1 out of 12 MIRU VNTR loci. These results indicate that MIRU VNTRs are stable over time and therefore are suitable for reliable follow-up of patients chronically infected with tuberculosis over long periods. Moreover, they support MIRU VNTR genotyping as a powerful first-line method followed by subtyping by IS6110 RFLP to define ongoing transmission clusters.

Antitubercular Agents↗
PubMed2002

Multiple Mycobacterium tuberculosis strains in early cultures from patients in a high-incidence community setting.

In an ongoing molecular epidemiology study, human immunodeficiency virus-negative patients with first-time pulmonary tuberculosis from a high-incidence community were enrolled. Mycobacterium tuberculosis strains were identified by restriction fragment length polymorphism analysis with two fingerprinting probes. Of 131 patients, 3 (2.3%) were shown to have a mixture of strains in one or two of their serial cultures. This study further investigated these cases with disease caused by multiple M. tuberculosis strains in the context of the molecular epidemiology of the study setting.

Adult↗
PubMed2002

Evaluation of young children in contact with adult multidrug-resistant pulmonary tuberculosis: a 30-month follow-up.

SETTING: The Western Cape Province of South Africa, an area with a high tuberculosis (TB) incidence, where initial multidrug resistance (MDR) among adult TB cases was 1.1% during 1992-1993. OBJECTIVE: To determine the long-term prevalence of TB infection and disease in children in household contact with adults with MDR pulmonary TB, and to establish the efficacy of chemoprophylaxis in preventing disease in these children. METHOD: Children <5 years old in contact with 73 MDR TB adults were evaluated. Disease was treated by prescribing at least 2 drugs to which the adult's strain was susceptible. The remaining children were classified as infected or noninfected and received chemoprophylaxis according to the index's strain susceptibility or were followed up and treated when indicated. All were followed up for 30 months. RESULTS: At the initial evaluation 125 children were seen, median age 27.5 months. Of these, 119 were followed up. Fourteen (12%) had disease, 61 (51%) were infected only, and 44 (37%) were noninfected. By 30-month follow-up, 29 (24%) had developed disease and 64 (54%) were infected only. Four adult-child pair Mycobacterium tuberculosis isolates were compared by DNA fingerprinting; 3 were identical. All children who developed TB disease were clinically cured. Two (5%) of 41 children who received appropriate chemoprophylaxis and 13 (20%) of 64 who did not, developed TB during follow-up (odds ratio: 4.97). CONCLUSION: The study confirms MDR TB transmission to childhood contacts. Seventy-eight percent of children were infected or developed disease. Appropriate chemoprophylaxis may prevent disease in these children.

Adult↗