Rapid detection of laboratory cross-contamination with Mycobacterium tuberculosis using multispacer sequence typing.

BACKGROUND: The ability to culture Mycobacterium tuberculosis from clinical specimens serves as the gold standard for the diagnosis of tuberculosis. However, a number of false-positive diagnoses may be due to cross-contamination of such specimens. We herein investigate such episode of cross-contamination by using a technique known as multispacer sequence typing (MST). This technique was applied to six M. tuberculosis isolates prepared within the same laboratory over a two-week period of time. RESULTS: MST analysis indicated a unique and common sequence profile between a strain isolated from a patient with proven pulmonary tuberculosis and a strain isolated from a patient diagnosed with lung carcinoma. Using this approach, we were able to provide a clear demonstration of laboratory cross-contamination within just four working days. Further epidemiological investigations revealed that the two isolates were processed for culture on the same day. CONCLUSION: The application of MST has been demonstrated to serve as a rapid and efficient method to investigate cases of possible cross-contamination with M. tuberculosis.

[Bronchial obstruction in asthmatic patients is underestimated by general practice physicians]. / L'obstruction bronchique des asthmatiques sous-estimée par les médecins généralistes.

INTRODUCTION: Many asthmatics have few or no symptoms despite severe obstruction of the airways. Physicians confronted with this phenomenon may therefore underrate the severity of the asthma and treatment may be insufficient. We studied the capacity of a group of general practitioners to assess the bronchial obstruction of patients presenting with varying degrees of symptoms and obstruction. METHODS: Ten asthmatics were initially examined by a pneumologist. The patients were classified as: normal (N; no dyspnoea, no wheeze, normal spirometry; n = 2); abnormal (A; dyspnoea and whistling, bronchial obstruction; n = 4); falsely normal (FN; mild or no dyspnoea and no wheeze, bronchial obstruction; n = 4). Ten randomly selected general practitioners, ignoring the protocol and aim of the study, examined 6 patients, 2 from each category. They then had to choose from a list of antiasthma treatments, those that would be appropriate for each patient, and assess on a visual analog scale (VAS) the degree of respiratory tract obstruction at the time of examination. Finally, questions on their knowledge and approach to asthma were asked. RESULTS: The VAS assessments (mm) were of 15.6, 65.2 and 11.0 in the FN, A and N patients, corresponding to a maximum expiratory volume per second of 52, 51 and 98% of the predicted values. Dyspnoea and wheeze were mentioned by each physician as criteria for respiratory tract obstruction. Although they also mentioned the laboured breathing, none noted the signs of thoracic distension, present in the falsely normal patients. None used the paradoxical pulse (inspiratory drop in systolic pressure) and/or spirometric measurements; nobody had noted that dyspnoea and wheeze can be lacking despite substantial obstruction of the airways. Five had prescribed beta 2 agonists alone, without corticosteroid therapy in falsely normal patients. CONCLUSION: General practitioners may underrate the severity of asthma, despite substantial obstruction of the respiratory tract, if there are few symptoms and hence under-treat falsely normal patients.

Diagnosis and severity of asthma in the elderly: results of a large survey in 1,485 asthmatics recruited by lung specialists.

BACKGROUND: Despite its high prevalence, epidemiological surveys on the diagnosis and severity of asthma in the elderly are seldom. OBJECTIVE: The objectives of our study were: (i) to describe the criteria, used by French lung physicians, for the diagnosis of asthma in the elderly (age > or = 65 years); (2) to investigate whether the age at the onset of asthma is related to the severity of asthma in the elderly. METHODS: 1,485 asthmatics (783 men and 702 women; mean age +/- SD = 73.2 +/- 6.0 years) were included in this descriptive survey. They were recruited by 379 lung specialists who filled in standardized questionnaire. RESULTS: 56% of men and 10% of women (p < 0.001) were smokers or ex-smokers FEV(1)/VC was significantly lower in men than in women (60.6 +/- 16.1 versus 66.1 +/- 16.9%; p < 0.001). Diagnostic criteria of asthma were both clinical and functional in 89% of cases. Bronchospasm reversibility was tested with inhaled beta(2)-agonists (89%) and/or oral corticotherapy (36%). Asthma had been diagnosed before the age of 20 years in 10.4% of the patients, between 20 and 50 years in 28.3%, between 51 and 65 years in 38.1%, and after the age of 65 years in 23.2%. Higher FEV(1) % of theoretical values and higher FEV(1)/VC were observed in subjects with late-onset asthma. The mean of FEV(1) % of theoretical values was 58.1 +/- 19.5% in subjects with asthma diagnosis before the age of 20 years, 60.5 +/- 20.4% in those with asthma diagnosis between the age of 20 and 50 years, 62.5 +/- 19.4% in those with asthma diagnosis between the age of 50 and 65 years, and 67.1 +/- 21.4% in those with asthma diagnosis after the age of 65 years (p < 0.001). The mean number of drugs taken was significantly lower (2.2 +/- 0.4) in late-onset asthma than in early-onset asthma (2.8 +/- 0.1; p < 0.001). CONCLUSIONS: This study suggests that the severity of asthma may depend on age at the onset of symptoms and diagnosis. Early diagnosis and treatment may prevent the adverse consequences of persistent asthma.