Contact tracing / pre-employment screening for pulmonary tuberculosis: Should positive mantoux test necessitates routine chest X-ray?

Abstract

Background: Pulmonary tuberculosis (PTB) remains a scourge in most developing countries. Mantoux skin test and
more commonly chest radiography are some of the methods of diagnosing the disease, especially with regard to
contact tracing and pre-employment screening. Regular use of radiography has both safety and cost implications.
This study aimed at establishing if any justification exists in requesting for chest radiographs in asymptomatic subjects
with a positive Mantoux skin test reaction.
Methods: 174 adults comprising PTB contacts and newly employed/admitted university staff/students were recruited
into the study. They were 89 males (51.1%) and 85 females (48.9%). All subjects had Mantoux test (using purified
protein derivative, PPD). Patients who had positive Mantoux reaction subsequently were subjected to posteroanterior
chest radiographic examination. Mantoux test and chest radiographic findings were then correlated with each other.
Results: 102 subjects (59.2%) had positive Mantoux reactions, while 27 subjects (31.1%) had abnormal chest
radiographs. There was no significant correlation between Mantoux readings and chest radiographic findings
(P=0.106).
Conclusion: It is concluded that other ancillary tests like sputum examination and/or, where available, Interferon and
ESAT tests should be carried out before chest radiograph is requested in subjects with positive Mantoux reaction.