Discordance in latent tuberculosis (TB) test results in patients with end-stage renal disease.

OBJECTIVES: This natural experiment was designed to assess the impact of exposure to an active case of tuberculosis (TB) on a group of immunosuppressed individuals, with end-stage renal disease over an extended follow-up. STUDY DESIGN: Close contacts of people with sputum smear-positive Mycobacterium tuberculosis are at high risk of infection, particularly immunosuppressed individuals. An infectious TB healthcare worker worked in a renal dialysis unit for a month before diagnosis, with 104 renal dialysis patients, was exposed for ≥8 h. METHODS: Patients were informed and invited for screening 8-10 weeks postexposure. They either underwent standard two-step assessment with tuberculin skin test (TST) and QuantiFERON®-TB Gold (Cellestis GmbH; QFN) interferon-gamma release assay (IGRA) or after consent, enrolled in a study where these two tests were performed simultaneously with T-SPOT®-TB (Oxford Immunotec Ltd; TSPOT). Patients within the study were followed up for 2 years from exposure, with QFN and TSPOT repeated at months 3 and 6 from the first testing. RESULTS: Of 104 exposed individuals, 75 enrolled in the study. There was a high degree of discordance among QFN, TSPOT and TST. This was seen at both the first time point and also over time in subjects who were retested. No patients had active TB at the baseline testing. None received treatment for latent TB infection. Over the following 2 years, no one developed TB disease. CONCLUSION: This study suggests that there is a low risk of progression to active TB in low-incidence countries even in high-risk groups. This plus the degree of the test result discordance emphasises the complexities of managing TB in such settings as it is unclear which of these tests, if any, provides the best diagnostic accuracy.

Large outbreak of isoniazid-monoresistant tuberculosis in London, 1995 to 2006: case-control study and recommendations.

We conducted a case­control study to examine risk factors for isoniazid-monoresistant Mycobacterium tuberculosis in an ongoing outbreak in London. Cases were defined as individuals with an isoniazid-monoresistant strain diagnosed from 1995 to the third quarter of 2006 with an indistinguishable restriction fragment length polymorphism (RFLP) or mycobacterial interspersed repetitive unit (MIRU)-variable number tandem repeats (VNTR) pattern who were resident in or had epidemiological links with London. Controls were all other individuals reported with tuberculosis to the Health Protection Agency London regional epidemiology unit or the HPA London TB Register during 2000 to 2005. Of 293 cases, 153 (52%) were sputum smear-positive compared with 3,266 (18%) of controls. Cases were more likely to be young adults (aged between 15 and 34 years), born in the United Kingdom (OR: 2.4; 95% CI: 1.7­3.4) and of white (OR: 2.9; 95% CI: 1.8­4.8) or black Caribbean (OR: 12.5; 95% CI: 7.7­20.4) ethnicity, a prisoner at the time of diagnosis (OR: 20.2; 95% CI: 6.7­60.6), unemployed (OR: 4.1; 95% CI: 3.0­5.6), or a drug dealer or sex worker (OR: 187.1; 95% CI: 28.4­1,232.3). A total of 113 (39%) of cases used drugs and 54 (18%) were homeless. Completion of treatment gradually improved in cases from 55% among those diagnosed up to the end of 2002 compared with 65% by the end of 2006. Treatment completion increased from 79% to 83% in controls from 2000 to 2005. There are complex social challenges facing many cases in this outbreak that need to be addressed if medical interventions are to be successful.

Health status of UK patients with active tuberculosis.

OBJECTIVE: To assess the impact of tuberculosis (TB) and its treatment on patients' health status. METHODS: Questionnaires were administered prospectively to patients at three clinics in London at diagnosis and 2 months into therapy. We assessed generic health-related quality of life (Short Form 36 [SF-36] and EQ-5D) and psychological burden (State-Trait Anxiety Short-Form, Center for Epidemiologic Studies Depression Scale, worry items). RESULTS: Of the 61 participants (response rate 94%), 89% were non-UK born, 67% had pulmonary TB and 38% were aged 30-45 years. At diagnosis, scores for all eight SF-36 dimensions were significantly worse than UK general population norm scores. At follow-up, scores had improved significantly (P < 0.01), except for physical functioning and general health perception, but remained below the UK norm, except for vitality and mental health. Respondents' mean anxiety and depression scores were high at diagnosis (48 and 22, respectively), and anxiety scores remained high at follow-up. Worries most frequently reported concerned patients' own health (92%) and that of their family (82%). CONCLUSIONS: TB patients suffer from significantly diminished health-related quality of life at diagnosis. Although treatment significantly improved patients' health status within 2 months, scores for many domains remain below UK norm scores. This emphasises the importance of a holistic approach to care and should inform the evaluation of future interventions.

Patient and health service delays in initiating treatment for patients with pulmonary tuberculosis: retrospective cohort study.

SETTING: Catchment population of the North Middlesex University Hospital (NMUH), London, UK. OBJECTIVE: To measure patient and health care delays in treatment of pulmonary tuberculosis. DESIGN: Retrospective cohort study of patients notified with pulmonary tuberculosis between 1 April 2001 and 1 March 2002. RESULTS: The median case finding delays were between 78 and 99 days. Median patient-related delay was between 34.5 and 54 days. Median health care-related delay was 29.5 days. Shorter case finding delays were found in patients born in a high prevalence country, patients presenting first to Accident and Emergency department (A&E), younger patients, and those with sputum smear-positive disease. In those presenting first to A&E, those born in a high prevalence country, and those with sputum-positive disease, this effect was predominantly due to shorter health care delays. Limitations of TB service capacity and organisational factors appeared responsible for up to half of the difference in delay between those presenting to A&E or general practitioners (GPs). CONCLUSION: Patient and health service delays contribute substantially to delays in patients accessing treatment. Considerable reduction in case finding delays may be achieved through changes in the capacity of tuberculosis services, and coordination of associated health services.

Outbreak of isoniazid resistant tuberculosis in north London.

BACKGROUND: A description is given of a major outbreak of isoniazid monoresistant tuberculosis (TB) chiefly in north London, including prisons. The earliest case was diagnosed in 1995 with most cases appearing after 1999. METHODS: Confirmation of a local cluster of cases was confirmed by restriction fragment length polymorphism (RFLP IS6110) typing or "rapid epidemiological typing" (RAPET). Further cases were found by retrospective analysis of existing databases, prospective screening of new isolates, and targeted epidemiological case detection including questionnaire analysis. RESULTS: By the end of 2001, 70 confirmed cases in London had been linked with a further 13 clinical cases in contacts and nine epidemiologically linked cases outside London. The epidemic curve suggests that the peak of the outbreak has not yet been reached. Cases in the outbreak largely belong to a social group of young adults of mixed ethnic backgrounds including several individuals from professional/business backgrounds. Compared with other cases of TB reported to the enhanced surveillance scheme in London during 1999-2001, the cases are more likely to be of white (26/70 (37%) v 1308/7666 (17%)) or black Caribbean ethnicity (17/70 (24%) v 312/7666 (4%)), born in the UK (41/70 (59%) v 1335/7666 (17%)), and male (52/70 (74%) v 4195/7666 (55%)). Drug misuse and/or prison detention are factors common to many cases. CONCLUSIONS: The investigation of the outbreak revealed significant problems on an individual patient and population based level including difficulties with contact tracing, compliance, and the risk of developing multidrug resistance. This incident has demonstrated the value of molecular strain typing in investigating an extensive outbreak of TB. This is the first documented outbreak involving a UK prison.

Cigarette smoke decreases the expression of secretory component in human bronchial epithelial cells, in vitro.

Epithelial secretory component (SC) is thought to be essential for immunologic protection of the respiratory tract from viral and bacterial infection, since it transports polymeric IgA from the basolateral to the luminal surface of epithelial cells. We have hypothesized that recurrent infection in airways of cigarette smokers is at least partly a consequence of cigarette smoke-induced downregulation of the expression and/or release of SC from airway epithelial cells, subsequently resulting in decreased transcytosis of secretory IgA to the airway lumen. To test this hypothesis, we have cultured human bronchial epithelial cells (HBEC) from surgical tissues and exposed these for 20 minutes to either air or cigarette smoke. Following exposure to cigarette smoke the HBEC cultures were incubated for a further period of up to 24 h, during which time separate cultures were processed by immunocytochemistry for the presence of SC, in a time-dependent manner. The stained HBEC cultures were evaluated by colour image analysis for the percentage of total cells staining for SC. Exposure to cigarette smoke significantly decreased the percentage of total HBEC staining for secretory component from a baseline value (median and interquartile[IQ]1, IQ3) of 35.9% (26.5, 41.6) to 15.7% (8.2, 25.4; p < 0.05) 1 h after exposure, compared with exposure to air. The percentage of cells staining for secretory component were further reduced to 5.3% (3.3, 6.4; p < 0.01), 6 h after exposure, compared to exposure to air. After incubation for 24 h following exposure to cigarette smoke, there was gross cell damage and the cells were not suitable for immunocytochemical analysis. These results suggest that short-term exposure to cigarette smoke may compromise the immune barrier function of the airway mucosa by decreasing the expression and/or release of epithelial SC, thereby decreasing the transcytosis of IgA necessary for inactivating the microbial pathogens in the airway lumen.

Interaction of cigarette smoke and house dust mite allergens on inflammatory mediator release from primary cultures of human bronchial epithelial cells.

Several studies have shown that exposure to cigarette smoke and/or house dust mite (HDM) can lead to increased airway inflammation in susceptible individuals. The underlying mechanisms, however, are not defined. To investigate the interaction between cigarette smoke and HDM allergen on mediator release from primary cultures of human bronchial epithelial cells. Confluent human bronchial epithelial cell cultures were exposed to cigarette smoke in the absence or presence of HDM allergen and investigated for the release of IL-8, IL-1beta, and sICAM-1. Damage to the epithelial cells themselves was assessed by release of 51Cr. On separate occasions, we investigated the effect of PTL11028, a highly potent and selective Der p1 inhibitor, on HDM allergen-induced release of IL-8, following activation of HDM allergen by incubation with cysteine. The effect of cigarette smoke exposure on the stability of these released mediators in prepared solutions in the absence/presence of reduced glutathione was also studied. Both HDM allergens and short-term (20 min) cigarette smoke exposure led to a significantly increased release of IL-8, IL-1beta and sICAM-1 from the epithelial cell cultures. Longer exposure (1-6 h) to cigarette smoke led to a dramatic decrease in the amount of these mediators detected in the culture medium. Whilst incubation of epithelial cultures with HDM allergen did not cause any significant change in the release of 51Cr from pre-loaded cells, cigarette smoke on its own led to a marked, exposure and incubation-time dependent increase in the release of 51Cr. Incubation with HDM allergen led to a significant, dose and time-dependent increase in the release of IL-8, which was further enhanced when the allergen extract was pre-activated with cysteine. This effect was completely abrogated by PTL11028, a novel Der p1 inhibitor. Prepared solutions of various concentrations of IL-8, IL-1beta and sICAM-1 exposed to cigarette smoke demonstrated a dramatic exposure time-dependent decrease in the detectable amount of these mediators, an effect which was abrogated by GSH. HDM-induced airway inflammation may include Der p-mediated release of inflammatory mediators from epithelial cells. Additionally, short-term cigarette smoke exposure may induce airway inflammation by release of inflammatory mediators from these cells, an effect which may be potentiated by Der p allergens. Longer term cigarette smoke exposure may cause damage to epithelial cells and changes in the structure of inflammatory mediators.

Effect of cigarette smoke on the permeability and IL-1beta and sICAM-1 release from cultured human bronchial epithelial cells of never-smokers, smokers, and patients with chronic obstructive pulmonary disease.

Although cigarette smoking is of paramount importance in the development of chronic obstructive pulmonary disease (COPD), only a small proportion of smokers develop the disease. We tested the hypothesis that the response of the bronchial epithelium to cigarette smoke (CS) differs in patients with COPD. Such a difference might explain in part why only some cigarette smokers develop the disease. We established primary explant cultures of human bronchial epithelial cells (HBEC) from biopsy material obtained from never-smokers who had normal pulmonary function, smokers with normal pulmonary function, and smokers with COPD, and exposed these for 20 min to CS or air. Measurements were subsequently made over a period of 24 h of transepithelial permeability and release of interleukin (IL)-1beta and soluble intercellular adhesion molecule-1 (sICAM-1). In addition, intracellular reduced glutathione (GSH) levels were measured after 24 h incubation. Exposure to CS increased the permeability of these cultures in all study groups, but the most marked effect was observed in cultures from patients with COPD (mean increase, 85.5%). The smallest CS-induced increase in the permeability was observed in HBEC cultured from smokers with normal pulmonary function (mean, 25.0%), and this was significantly lower than that of HBEC from never-smokers (mean, 53.4%) (P<0.001). Compared with exposure to air, exposure to CS led to a significantly increased release of these mediators from cultures of the never-smoker group (mean 250.0% increase in IL-1beta and mean 175.3% increase in sICAM-1 24 h after exposure) and COPD group (mean 383.3% increase in IL-1beta and mean 97.4% increase in sICAM-1 24 h after exposure). In contrast, CS exposure did not influence significantly the release of either mediator from the cells of smokers with normal pulmonary function. Levels of intracellular GSH were significantly higher in cultures of HBEC derived from smokers, both those with normal pulmonary function and those with COPD, compared with cultures from healthy never-smokers. Exposure to CS significantly decreased the concentration of intracellular GSH in all cultures. However, the fall in intracellular GSH was significantly greater in cells from patients with COPD (mean 72.9% decrease) than in cells from never-smokers (mean 61.4% decrease; P = 0.048) or smokers with normal pulmonary function (mean 43.9% decrease; P = 0.02). These results suggest that whereas smokers with or without COPD demonstrate increased levels of GSH within bronchial epithelial cell cultures, those with COPD have a greater susceptibility to the effects of CS in reducing GSH levels and causing increased permeability and release of proinflammatory mediators such as IL-1beta and sICAM-1.

Cigarette smoke potentiates house dust mite allergen-induced increase in the permeability of human bronchial epithelial cells in vitro.

Although studies have suggested that exposure to cigarette smoke (CS) may be associated with the development of atopy, the mechanisms underlying this are not clearly understood. It has been suggested that CS impairs the barrier function of the airway epithelium, leading to increased access of allergens such as those of the house dust mite (HDM) Dermatophagoides pteronyssinus (Der p) to antigen-presenting cells, with subsequent allergic sensitization. In order to test this hypothesis, we established primary explant cultures of human bronchial epithelial cells (HBEC) in cell culture inserts, and exposed these for 20 min, 1 h, 3 h, and 6 h to CS or air in the absence or presence of 300 ng/ml Der p, and then further incubated the cultures over a period of 24 h. The HBEC cultures were assessed for changes in permeability as measured by changes in: (1) electrical resistance (ER); and (2) passage of 14C-labeled bovine serum albumin (14C-BSA) and Der p allergens across the HBEC cultures. We also assessed the effects of protease inhibitors and the antioxidant glutathione (GSH) in this experimental system. Damage to HBEC cultures was assessed by the release of [51Cr]sodium chromate from prelabeled cells, and by release of lactate dehydrogenase (LDH). Twenty minutes of exposure to CS as compared with exposure to air did not significantly alter either the ER or passage of 14C-BSA across the HBEC cultures. In contrast, incubation with Der p led to a significant increase in the permeability of HBEC cultures, an effect that was enhanced by exposure to CS but was abrogated by the specific protease inhibitors and GSH. Passage of Der p was also increased by exposure to CS. Exposure of HBEC cultures to CS led to a significant release of 51Cr and LDH from these cells as compared with cells exposed to air. This effect was augmented further when HBEC cultures were incubated with Der p. Exposure of HBEC cultures for 1 h, 3 h, and 6 h to CS led to a markedly significant dose- and time-dependent increase in the permeability of these cells. These results suggest that exposure to CS significantly enhances Der p-induced decreases in electrical resistance and the increased passage across HBEC cultures of 14C-BSA and of the Der p allergen itself.

Lymphocyte infiltration and thickness of the nasal mucous membrane in perennial and seasonal allergic rhinitis.

We have used immunocytochemical techniques to study infiltration by lymphocytes in biopsy specimens of the nasal mucosal membrane in 24 atopic patients and 10 normal volunteers. Twelve patients had perennial rhinitis and 12 had seasonal allergic rhinitis (SR) to grass pollen. Biopsy specimens were taken both in and out of the pollen season in patients with SR. Biopsy specimens were strained with the indirect immunoperoxidase technique and monoclonal antibodies to CD3, CD4, CD8, CD22, and CD25. T helper cells (CD4+) and CD24+ cells were significantly more numerous in patients exposed to allergen (those with perennial rhinitis and SR in season) compared with normal volunteers, whereas values for SR out of season were intermediate. The thickness of the nasal epithelium was significantly (p < 0.05) greater in biopsy specimens from patients with perennial rhinitis (mean, 51.43 microns) than in those from patients with SR in season (median, 32.44 microns). These results suggest that in allergic rhinitis, natural exposure to allergen is accompanied by increased infiltration of the nasal mucous membrane by T-helper and CD25+ cells.

Topical glucocorticoids inhibit activation by allergen in the upper respiratory tract.

We have studied the effect of a topically administered glucocorticoid, fluticasone propionate (FP), on infiltration and activation of eosinophils in the nasal mucosa after provocation with allergen. Forty-four patients with seasonal allergic rhinitis entered a double-blind, crossover study in which they underwent treatment with either FP (200 micrograms once daily) or identical placebo for 2 weeks. Patients then underwent nasal-allergen provocation followed by nasal lavage and biopsy at one of several time points between 0 and 8 hours. Patients subsequently received the alternate treatment for 2 weeks before repeat allergen provocation, nasal lavage, and biopsy, as before. Biopsy specimens of nasal mucosa obtained during the immediate allergic response demonstrated an influx of eosinophils (stained by monoclonal antibody EG1) of similar magnitude during both FP and placebo treatment. Significantly, fewer eosinophils in these biopsy specimens were activated (stained by monoclonal antibody EG2) after treatment with FP compared with that after placebo treatment (median values, 8.8 and 36.6 cells per square millimeter, respectively; p less than 0.02). The concentration of eosinophil cationic protein in nasal lavage fluid was significantly elevated above baseline from 2 to 8 hours after allergen, and this increase was abolished by treatment with FP. These results suggest that topical glucocorticoids inhibit allergen-induced activation of eosinophils in allergic rhinitis.

Time course of cellular infiltration in the nasal mucosa during the immediate allergic reaction.

In 23 patients with allergic rhinitis, biopsies of the nasal mucous membrane were taken at one of the following times after challenge of one nostril with allergen: 0 (baseline) (n = 7), 1/2 h (n = 6), 1 h (n = 5), and 2 h (n = 5). In the nostril stimulated by allergen there was a transient early phase influx of eosinophils while the numbers of stainable mast cells decreased, probably due to their degranulation. In the contralateral unstimulated nostril, there was no change in numbers of eosinophils but the numbers of stainable mast cells decreased. These results support the proposed role in allergic rhinitis of the mast cell and eosinophil, and suggest that the eosinophil may be a rapidly mobilized effector cell.

Allergen-induced changes in the nasal mucous membrane in seasonal allergic rhinitis: effect of nedocromil sodium.

We have obtained biopsy specimens of the nasal mucous membrane before and during the grass-pollen season in 22 patients with seasonal allergic rhinitis to grass pollen to assess the effects on cellular infiltration of natural exposure to allergen. Biopsy sections were examined by light microscopy, and quantitative assessment was made of numbers of mast cells and eosinophils. The patients were divided into 11 who were treated with placebo and 11 patients who were treated with topical nedocromil sodium. In the group as a whole, there was a significant (p less than 0.001) increase in mast cell density in tissue sections from biopsy specimens obtained during the season compared with out of season (median values, 55.0 and 15.5 cells per square millimeter, respectively). There was also a significant (p less than 0.02) increase in the density of eosinophil infiltration during the season compared with out of season (median values, 6.3 and 0 cells per square millimeter, respectively). Treatment with nedocromil sodium significantly (p less than 0.02) inhibited the accumulation of mast cells but not eosinophils. Compared with the placebo-treated group, the group treated with nedocromil demonstrated a significant (p less than 0.025) reduction in the requirements for treatment with concomitant medication (terfenadine tablets and xylometazoline/antazoline eye drops). These results indicate that natural exposure to allergen in patients with seasonal allergic rhinitis is accompanied by infiltration of mast cells and eosinophils into the nasal mucous membrane. The clinical efficacy of nedocromil sodium in this condition may be related to inhibition of infiltration by mast cells.

Morphological integrity of the bronchial epithelium in mild asthma.

In severe asthma bronchial epithelial cells are damaged and detached, and it has been proposed that such damage might lead to the bronchial hyperresponsiveness that characterises asthma. To investigate the relation between airway hyperresponsiveness and epithelial damage, biopsy specimens of the bronchial mucus membrane were obtained at fibreoptic bronchoscopy from 11 patients with mild atopic asthma and airway hyperresponsiveness (provocative concentration of methacholine causing a 20% fall in FEV1 (PC20) less than 1.0 mg/ml), and from 17 healthy non-atopic subjects who did not have airway hyperresponsiveness (PC20 methacholine greater than 8.0 mg/ml). Observers who were blind to the presence or absence of asthma examined the biopsy specimens by light and electron microscopy. Epithelial cells, intercellular spaces, and goblet cells were counted. Intercellular junctional complexes were examined, and a semiquantitative assessment was made of ciliary loss, non-parallel central ciliary filaments, and vacuoles in ciliated cells. There were no differences between the asthmatic and healthy groups in any of these measurements. These findings indicate that airway hyperresponsiveness may be present when there is no apparent change in the structure of the bronchial epithelium.

Role of computed tomography in evaluating asbestos related lung disease.

To find how computed tomography (CT) may be effectively used in individuals with suspected asbestos related lung disease 30 men with a history of exposure to asbestos were studied. All subjects underwent high kilovoltage posteroanterior and left lateral chest radiographs and chest CT. Eighteen were randomly selected asbestos workers referred for routine surveillance. The remaining 12 were patients who had been referred for investigation of respiratory symptoms or abnormal routine chest radiograph, or both, and found to have chest radiographic changes compatible with asbestos related lung disease. In the group referred for routine surveillance both pleural shadowing and pulmonary shadowing were shown on CT but not chest radiographs in only one case. Five were thought to have pleural shadowing on chest radiographs but this was confirmed on CT in only one case. All 12 patients referred for investigation showed pleural shadowing on chest radiographs; this was confirmed in all cases on CT which also showed unsuspected pulmonary shadowing in five cases. These findings suggest that it is not appropriate to use chest CT routinely in all asbestos workers referred for routine surveillance. When CT is used selectively in those with pleural shadowing on plain chest radiography, however, it is helpful in refuting or confirming the presence of pleural disease and may show unsuspected pulmonary shadowing.