Tuberculosis not verified by culture in a low incidence country

Abstract

The objective was to evaluate the magnitude, diagnostic basis and characteristics of patients notified with tuberculosis (TB) not verified by culture. All patients in Denmark notified with TB between 1995 and 1999 were identified through the national TB register. Nationwide culture results were obtained from the International Reference Laboratory of Mycobacteriology. The proportion of culture verification decreased from 91% in 1995 to 80% in 1999. A total of 2518 patients were notified, of which 374 (14.9%) were not verified by culture. For 80 (3.2%) patients no specimens were submitted. Instead the diagnosis was mainly based on X-ray (72.6%) for patients with pulmonary TB and histology (38.3%) for patients with extrapulmonary TB. For 216 patients aged 0-14 y, 74 (34.3%) were not verified by culture. The proportion of TB not verified by culture in Denmark is low compared to other European countries. Some cases may be well explained, e.g. children with a close contact suffering from TB or patients with extrapulmonary TB with limited number of specimens. However, for a minority group of patients with pulmonary TB there were no obvious reasons why specimens were not submitted for culture. Culture verification should remain a priority when possible.