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Biomedical subjects

N Beyers

Publications and source records attributed to N Beyers.

At least 73 records · Page 4Linked to original sources
PubMed1999

Evaluation of young children in household contact with adult multidrug-resistant pulmonary tuberculosis cases.

BACKGROUND: The prevention and management of multidrug-resistant (MDR) tuberculosis has received much attention, but little attention has been given to children with MDR tuberculosis or children in contact with adults with MDR tuberculosis. The aim of this study was to determine the prevalence of tuberculous infection and disease in childhood contacts of adults with MDR pulmonary tuberculosis. METHOD: All children <5 years of age in household contact with 75 recently diagnosed adults with MDR pulmonary tuberculosis were evaluated. Evaluation included clinical examination, tuberculin skin test, chest radiography and culture for Mycobacterium tuberculosis from gastric aspirates. RESULTS: One hundred twenty-eight children, median age 27 months, were evaluated. Fifty children had recent contact with other adult tuberculosis cases. Sixty-six children previously had chemoprophylaxis or treatment of whom 36 defaulted treatment or received insufficient chemoprophylaxis. One child had HIV infection. Forty-seven children were classified as noninfected, 66 were considered infected only (Mantoux test, > or = 15 mm) and 15 had disease. Three children, who had not previously received antituberculosis drugs, had positive cultures for M. tuberculosis; all were multidrug-resistant. CONCLUSION: This study documents the transmission of multidrug-resistant M. tuberculosis to childhood contacts, the development of disease in these contacts and the importance of knowing the index case's M. tuberculosis susceptibility pattern in choosing a proper treatment regimen for the childhood contact.

Adult↗
PubMed1999

Childhood tuberculosis in an urban population in South Africa: burden and risk factor.

AIM: To study the epidemiology of childhood tuberculosis (TB) in a developing country. SETTING: Two urban communities of Cape Town, South Africa with a TB case notification rate of 1149/100 000. DESIGN: Retrospective descriptive study using the national population census (1991), 10 year official TB notification records, and a geographical information system. RESULTS: The case notification rate of TB in children 0-5 years old was 3588 cases/100 000 children aged 0-5 years, 3.5 times the case notification rate in adults. Children (0-14 years) accounted for 39% of the total case load. Childhood TB case notification rate correlated with parental education (r = -0.64), annual household income (r = -0.6), and crowding (r = 0.32). CONCLUSION: Children, especially those living in poor socioeconomic conditions, form an important epidemiological group and account for a notable proportion of the morbidity caused by TB. Efforts to improve TB control must therefore not only target adults (case detection and cure of infectious cases) but also children (screening of child contacts of adult cases) and the socioeconomic living conditions.

Adolescent↗
PubMed1999

Impact of social interactions in the community on the transmission of tuberculosis in a high incidence area.

BACKGROUND: Tuberculosis (TB) is transmitted by close contact with an infectious person. It is assumed that close contact occurs amongst household members and that contact outside the house is "causal" and does not play a major role in the transmission of TB. METHODS: This study was conducted in an impoverished area with a high incidence of TB and a low HIV seropositive prevalence. Thirty three households with 84 TB patients were identified between February 1993 and April 1996 and the transmission of TB was studied by combining Mycobacterium tuberculosis fingerprinting with in depth sociological interviews. RESULTS: Forty two strain genotypes were identified in the 84 patients. In 15 households all the patients had identical strains, in nine households all the patients had different strains, and in nine households some patients had identical strains and one had a different strain. In 26 houses at least one patient had a strain which formed part of a larger community cluster and in 12 of these households the patient(s) had contact with a community member who had the identical strain. In 58% of the cases the contact took place while drinking in social groups. CONCLUSION: In high incidence areas contact outside the household may be important for the transmission of TB. This contact often takes place during recreation which, in the case of this study of impoverished people, consisted of drinking in social groups. Social interaction patterns should be studied and understood for effective implementation of control strategies.

Disease Transmission, Infectious↗
PubMed1999

Mannose-binding protein B allele confers protection against tuberculous meningitis.

Inhalation is the principal mode of entry for Mycobacterium tuberculosis in humans. Primary infection is usually restricted to the lungs and contiguous lymph nodes. In a subset of infected individuals, predominantly children, the infection is spread hematogenously to the meninges. The host factors that influence the development of tuberculous meningitis have not been well elucidated. The mannose-binding protein (MBP), a serum protein, is considered as an "ante-antibody." MBP has been shown to bind mycobacteria and acts as an opsonin in vitro. Although MBP plays a role in first-line host defense, it may under certain circumstances be deleterious to the host. In tuberculosis (TB), MBP may assist the spread of this intracellular pathogen. Therefore, we hypothesized that MBP genotypes that result in a phenotype of low MBP levels might be protective. We studied a well-defined South African population in which TB has reached epidemic levels. We found that the MBP B allele (G54D), which disrupts the collagen region of the protein and results in low MBP levels, was found in 22 of 79 (28%) of the TB-negative controls from the same community, compared with 12 of 91 (13%) of the patients with pulmonary TB (p < 0.017), and 5 of 64 (8%) of patients with tuberculous meningitis (p < 0.002). In addition, we found significantly lower serum MBP concentrations in TB-negative controls compared with postacute phase, fully recovered TB patients (p < 0.004). These findings suggest that the MBP B allele affords protection against tuberculous meningitis.

Adult↗
PubMed1998

Skeletal tuberculosis: dactylitis and involvement of the skull.

A re-emergence of tuberculosis (TB) is occurring world wide in both developed and developing countries. The clinical picture caused by infection with M. tuberculosis may simulate many other disease entities and may result in unnecessary investigations with a delay in diagnosis and treatment. Skeletal TB tends to be isolated to one anatomical site. We report a 6-year-old boy with disseminated skeletal TB with dactylitis resembling sickle cell anaemia and lytic lesions similar to those which are often seen in neuroblastoma, Langerhans' cell histiocytosis and leukaemia. The clinician should be aware that TB can mimic almost any disease and recognise the radiographic appearances of skeletal tuberculous lesions.

Arthritis, Infectious↗
PubMed1998

Management of children with tuberculosis admitted to a pediatric intensive care unit.

OBJECTIVES: To review the incidence, clinical features, ventilatory support and outcome of children with tuberculosis (TB) admitted to a Pediatric Intensive Care Unit (PICU) in a region with an high incidence of TB. MATERIALS AND METHODS: The study was performed in a PICU situated in a province with a extremely high incidence of TB (> 700 new cases/ 100000/year). This is a retrospective descriptive study of TB admissions to the PICU in a 4-year period. Data regarding indications for admission, clinical picture, duration of ventilation, PICU and hospital stay were collected from patient files. Outcome measures included mortality and long term morbidity. RESULTS: Of the 1862 children admitted to the hospital for TB during the 4 years, 57 (3.1%) required PICU admission (1 to 6% of annual admissions). Of these 57 children 41 (72%) were admitted for respiratory failure. In 12 cases TB was the cause of the respiratory failure, 17 cases suffered from other respiratory diseases and in 12 cases the cause was nonrespiratory disease of which TB meningitis (n=8) was the most common. Mechanical ventilation was indicated in 43 (75%) patients who were ventilated for 7.3+/-11.5 days. The duration of PICU admission was 10.2+/-2.4 days whereas the duration of hospitalization was 70.3+/-148.9 days. The PICU mortality was 23% with TB meningitis having the highest mortality of 75%. CONCLUSIONS: In a region with a high incidence of TB, tuberculous patients constitute up to 6% of PICU admissions. A high degree of suspicion for the diagnosis is needed because in 30% of our cases the diagnosis was not initially considered.

Adolescent↗
PubMed1998

Procedures for developing a simple scoring method based on unsophisticated criteria for screening children for tuberculosis.

OBJECTIVE: To develop a scoring system for screening children for tuberculosis (TB) and for selecting suspects for further investigation in tuberculosis control programmes. Application of the score model, which would not require sophisticated or expensive technology, would be directed towards resource-poor countries with high prevalences of tuberculosis, where health care workers have to deal with diagnostic problems away from district hospitals or diagnostic facilities. DESIGN: Based on contributions from members of an IUATLD task group from 10 countries on the use of diagnostic criteria in childhood tuberculosis, criteria were selected to be used as elements in a score model. Data were collected by standardised questionnaire on 879 subjects aged under 15 years. Of these, 794 were considered probable or confirmed cases of tuberculosis by the diagnosing doctors. From each record, the criteria/procedures used in the diagnosis of probable/confirmed TB and regarded by the doctors as relevant criteria were selected. Bacteriology, histology and chest radiography were used either singly or collectively as the definitive reference (gold standard) against which the more subjective criteria (symptoms, clinical signs, skin test) would be evaluated. The latter criteria cited as relevant were then ranked and further explored for inclusion in the score model. The relative importance of each criterion to every other criterion on the list was expressed as weights, determined by employing a logarithmic least squares method to solve the ratio scale estimation problem which underlies decision-making involving more than one criterion. The resultant values were then assigned to each criterion in the final score model. RESULTS: The five clinical criteria thought to be most relevant as predictors of disease in children were history of contact with a case of tuberculosis, positive skin test, persistent cough, low weight for age, and unexplained/prolonged fever. In selecting the optimal cut-off points for the model at which tuberculosis would be suspected, low sensitivity and specificity (below 70%) but reasonably good positive predictive values (60%-77%) were obtained, depending on age group and epidemiological setting. In low tuberculosis prevalence settings, heavy reliance is placed by the model on a history of contact with a household case of tuberculosis and on a positive skin test, both of which have to be true. For high prevalence settings, more or less equal weighting is assigned to all five elements. Case contact and skin tests are less important, with low body weight, prolonged fever and cough being more indicative of tuberculosis. CONCLUSION: The model provides for epidemiological differences between target populations and should prove successful as a screening tool to select children for further investigation by radiography and bacteriology.

Adolescent↗
PubMed1998

Signals that regulate the host response to Mycobacterium tuberculosis.

An appropriate T helper (Th) 1 immune response is required for the elimination of Mycobacterium tuberculosis. The factors regulating the polarization of mouse or human T cells to produce Th1 or Th2 cytokines are briefly reviewed. These factors include host genetics, cytokines present at the site of T cell activation, the type, dose and localization of antigen, the type of antigen-presenting cells, the engagement of different costimulatory molecules, steroid hormones and age. T cells of children produce low levels of gamma-interferon and we hypothesize that this may partly explain the differences in the clinical manifestations of tuberculosis in children and adults. Given that Th2 cytokines inhibit Th1 responses, the question arises of whether individuals mounting prominent Th2 responses, manifested by high serum IgE levels, are more susceptible to M. tuberculosis. In a community with a high incidence of tuberculosis, serum IgF levels, a marker of prominent Th2 responses, correlate with disease incidence and with socioeconomic deprivation. We propose that Th2 immune dominance, probably induced by intestinal parasites, enhances susceptibility to tuberculosis. Furthermore, our finding that serum IgE declines in patients following active tuberculosis argues that tuberculosis down-regulates Th2 responses.

Age Factors↗
PubMed1997

Adenylate kinase activity in the cerebrospinal fluid of children with tuberculous meningitis and its relationship to neurological outcome.

Cerebrospinal fluid (CSF) adenylate kinase activity was determined in 88 children (mean age 32.6 months) at stage II (n = 40) and stage III (n = 48) tuberculous meningitis (TBM) at, or shortly after, the initiation of treatment, and at weekly intervals thereafter for the first month of treatment, and in 60 children (mean age 40 months) investigated for, but later considered not to have meningitis. CSF adenylate kinase activity in this latter group ranged from 0 to 1.27 u/l (mean 0.59 u/l). Mean CSF adenylate kinase activity during the first week of therapy in children at stage II TBM (2.95 u/l; range 0-9.22 u/l) differed significantly (p = 0.03) from that in children at stage III TBM (5.62 u/l; range 0-18.93 u/l). CSF adenylate kinase activity did not differ between children at stage II and stage III TBM during any of the 3 subsequent weeks. CSF adenylate kinase activity was not related to CSF cell count, total protein or glucose concentration or intracranial pressure at any point during the first month of treatment, but was related to CSF lactate during the first week of therapy (p = 0.001). Consecutive determinations of CSF adenylate kinase activity were available in 34 children. Although CSF adenylate kinase activity tended to increase or decrease in keeping with changes in clinical condition this was not always the case. The close relationship of CSF adenylate kinase activity and lactate concentrations suggests that adenylate kinase activity reflects hypoxic cerebral metabolism and it was unusual for children with increased CSF adenylate kinase activity at the time of diagnosis to be clinically normal on completion of 6 months of antituberculosis treatment. Any treatment modality which significantly reduced CSF adenylate kinase activity in children early in the course of TBM would probably be of clinical benefit to the patients.

Adenylate Kinase↗
PubMed1997

Extraction of rules for tuberculosis diagnosis using an artificial neural network.

The treatment of tuberculosis (TB) is a major challenge throughout the world. The Western Cape Region of South Africa has the highest occurrence of TB in the world. Here, TB is increasing due to improperly managed treatment programmes and inadequate facilities. The development of rules to aid medical practitioners in the early and accurate diagnosis of tuberculosis should prove worthwhile. A method to extract such diagnostic rules from an artificial neural network is presented. These rules accurately represent the knowledge embedded in the "raw" TB data.

Diagnosis, Computer-Assisted↗
PubMed1997

Sociological and anthropological factors related to the community management of tuberculosis in the Western Cape communities of Ravensmead and Uitsig.

OBJECTIVE: To determine the sociocultural understanding of tuberculosis among patients and their household members. DESIGN: Qualitative descriptive study. SETTING: Two adjacent Western Cape suburbs with a population of approximately 35,000, a tuberculosis incidence of > 1,000/100,000 and a surface area of 2.42 km2. SUBJECTS: Twenty-three adult patients on treatment for tuberculosis and their adult household members. INTERVENTIONS: None. METHODOLOGY: Consecutive selected adult tuberculosis patients and their household members were interviewed with an open-ended interview schedule. General household and community conditions and non-verbal responses were recorded. RESULTS: There were relatively affluent but also severely deprived households with severe overcrowding. Substance abuse was common. Patients had limited understanding and knowledge about health, hygiene and the cause of tuberculosis. There was a perception of both physical and social distance between patients and health care providers. All patients relied exclusively on the conventional biomedical curative approach of the medical system to deal with tuberculosis.

Adult↗
PubMed1997

A prospective evaluation of children under the age of 5 years living in the same household as adults with recently diagnosed pulmonary tuberculosis.

SETTING: A South African suburb with a high tuberculosis incidence (> 800/100,000). OBJECTIVE: To determine the prevalence of tuberculosis infection and disease in children less than 5 years of age who were in close household contact with adults with pulmonary tuberculosis. DESIGN: Prospective clinical study. SUBJECTS: Children under 5 years of age (of whom > 98% had been BCG vaccinated in the neonatal period) in household contact with an adult with tuberculosis. INVESTIGATION: Clinical investigation, Mantoux skin testing, chest radiography, gastric aspirate culture for Mycobacterium tuberculosis. RESULTS: Of 155 children younger than 5 years in contact with 80 index cases (83% smear positive), 14% were infected and 34% diseased. Children aged under 2 years had more severe disease (endobronchial tuberculosis and bronchial compression). Of 154 household members aged over 5 years who were assessed, 17 had culture proven pulmonary tuberculosis (13 smear positive) and a further 16 were placed an antituberculosis treatment on the basis of radiological evidence. CONCLUSION: In a high tuberculosis incidence area evaluation of and chemoprophylaxis for childhood contacts of adults with pulmonary tuberculosis is a rewarding procedure. The detection of culture and smear positive pulmonary tuberculosis amongst adolescent and adult household contacts emphasizes the role of contact tracing in the detection of infectious cases of pulmonary tuberculosis and the prevention of the spread of tuberculosis.

Adolescent↗
PubMed1996

A decade of experience with Mycobacterium tuberculosis culture from children: a seasonal influence on incidence of childhood tuberculosis.

SETTING: A tertiary care hospital in the Western Cape Province of South Africa from November 1983-October 1993. OBJECTIVE: Evaluation of the source of all cultures of Mycobacterium tuberculosis from children aged < 13 years and documentation of the mean time for culture with Löwenstein-Jensen (LJ) medium and a radiometric method (Bactec). RESULTS: One thousand six hundred and sixty cultures of M. tuberculosis were obtained from 1204 children (638 (53%) males and 566 (47%) females). The median time to a positive culture result was 65 days with LJ medium and 23 days with Bactec (P < 0.0001). Gastric aspirate provided 1298 cultures (78%) from 983 children (82%) of whom 52% were aged < 2 years. Ninety-six positive sputum specimens were from 79 children (7%) of whom 70% were > 5 years. Significantly more positive cultures were obtained during the late winter and early spring (P < 0.001), and a similar trend was found for tuberculous meningitis. CONCLUSION: The use of a radiometric culture method has expedited the confirmation of tuberculosis in childhood in our hospital. Even in children < 3 months of age the diagnosis of tuberculosis can often be confirmed by culture. The documented increase in childhood tuberculous disease in spring suggests an increased transmission of tuberculous infection in autumn and winter in our community.

Age Distribution↗