Culture confirmation of tuberculosis cases in Birmingham, UK

• Published in: Scandinavian journal of infectious diseases 2013-10, Vol.45 (10), p.746-751
• Main Authors: Hayer, Kalbir S., Sitch, Alice J., Dedicoat, Martin, Wood, Annette L.
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Aged; Aged, 80 and over; Bacteriological Techniques - methods; Birmingham; Cross-Sectional Studies; culture confirmation; Diagnostic Tests, Routine - methods; factors; Female; Humans; Male; Middle Aged; Mycobacterium tuberculosis - growth & development; Mycobacterium tuberculosis - isolation & purification; Sensitivity and Specificity; Tuberculosis; Tuberculosis - diagnosis; Tuberculosis - microbiology; United Kingdom; Young Adult
• ISSN: 0036-5548; 1651-1980
• DOI: 10.3109/00365548.2013.804944

Abstract Background: The proportion of culture-confirmed tuberculosis (TB) cases in Birmingham had gradually decreased to less than 65% in 2008. Reasons for this were unclear, therefore this study assessed diagnostic methods used for confirming TB and reviewed factors involved in positive culture. Methods: A cross-sectional study was carried out. A list of notified TB cases for Birmingham in those aged 16 y and over in 2009 was collated. Where no positive culture was recorded, further data were collected from hospital databases and case notes. Results: Of 449 TB cases, 419 (93%) had samples taken for culture testing. Of all cases, 309 (69%) were confirmed by culture testing; of those receiving culture testing, 73% were confirmed. Pulmonary TB was identified as a predictor of positive culture in both the unadjusted and adjusted analyses: odds ratio (OR) 2.05, 95% confidence interval (CI) 1.32-3.19, and OR 2.32, 95% CI 1.29-4.17, respectively. Gender, age, ethnicity, UK born, and treatment delay were not significantly associated with positive culture. Of 140 cases not confirmed by culture, 129 (92%) had their diagnosis supported by at least one other test. Conclusion: The vast majority of TB cases had microbiological specimens taken to help confirm the disease. Furthermore, culture confirmation rates in Birmingham were meeting national targets in 2009. However culture confirmation rates were significantly lower in extrapulmonary TB, therefore further work is suggested in this group. The role of other investigations (e.g. interferon-gamma release assay (IGRA), Mantoux) is unclear. Further collaboration between clinicians, histopathologists, and microbiologists is advised to ensure samples are sent appropriately and culture confirmation is optimized.