Guidelines on the Prevention and Control of Tuberculosis in Ireland

<strong>Guidelines</strong> on the Prevention and Control of Tuberculosis in Ireland 2010HSE/HPSCAll patients (adults, adolescents and children who are capable of producing sputum) suspected of havingpulmonary TB should ideally have three sputum specimens obtained for microscopic examination. Whenpossible at least one early morning specimen should be obtained. 25 The recommendations in chapter 4 onlaboratory diagnosis should be implemented in this regard.A sputum smear positive patient has a minimum of one sputum specimen positive for AFB by microscopy. 24The diagnosis of sputum smear negative pulmonary TB should be based on the following criteria:• At least three negative sputum smears (including at least one early morning specimen)• Chest X-ray findings consistent with TB and• Lack of response to a trial of broad-spectrum antimicrobial agents. 25As fluoroquinolones are active against M. tuberculosis complex and thus cause transient improvement inpersons with TB, they should be avoided. For such patients, if facilities for culture are available, sputumcultures should be obtained. In persons with known or suspected HIV infection, the diagnostic evaluationshould be expedited. 25An assessment of the likelihood of drug resistance based on history of prior treatment, exposure to apossible source case having drug-resistant organisms and the community prevalence of drug resistanceshould be obtained from all patients.In an era of increasing drug resistance every effort should be made to obtain bacteriological diagnosis inorder to obtain drug susceptibility data. This is also critical for obtaining molecular typing data essentialfor contact tracing and TB control programmes. For patients in whom drug resistance is considered tobe likely, culture and drug susceptibility testing for isoniazid, rifampicin, ethambutol, pyrazinamide andstreptomycin should be performed promptly. 25Where extrapulmonary TB is suspected, specimens from the suspected sites of involvement shouldbe obtained for microscopy, culture and histology. 25 The NICE guidelines suggest various site-specificinvestigations for the diagnosis of extrapulmonary TB (see table 5.1). 26CDC now recommends that NAAT should be performed on at least one respiratory specimen from eachpatient with signs and symptoms of pulmonary TB for whom a diagnosis of TB is being considered buthas not yet been established and for whom the test result would alter case management or TB controlactivities such as contact tracing. 158 All those wishing to undertake NAAT on suspected cases of pulmonaryTB should seek advice from the local consultant microbiologist (see chapter 4 on laboratory diagnosisof TB).-61-