Guidelines on the Prevention and Control of Tuberculosis in Ireland

<strong>Guidelines</strong> on the Prevention and Control of Tuberculosis in Ireland 2010HSE/HPSCReactivation: The advancement of old LTBI (whether previously detected or not) into active TBShort-course treatment: Modern 6 month treatment regimens for active TB (previously treatment hadbeen for at least 12 months)Smear: A laboratory technique for preparing a specimen so that bacteria can be visualised microscopically.The results for sputum acid-fast bacteria (AFB) smears typically are reported as numbers of AFB per highpoweredmicroscopy field, or else as a graded result from no AFB to 4+ AFB. The quantity of stainedorganisms is associated with the degree of infectiousness.Sputum: Mucous expelled from the bronchi and lungs by coughing (or retrieved from gastric washings,see above). Sputum is examined for TB bacteria by microscopic examination of stained smear; part of thesputum can also be used for culture.Sputum smear negative TB Case:A sputum smear negative TB case has:o At least three negative sputum smears (including at least one early morning specimen)o Chest X-ray findings consistent with tuberculosis ando Lack of response to a trial of broad-spectrum antimicrobial agents (Note: because thefluoroquinolones are active against M. tuberculosis complex and thus may cause transientimprovement in persons with tuberculosis, they should be avoided)It should be noted that in making a diagnosis based on the above three criteria, a clinician who decidesto treat with a full course of antituberculosis chemotherapy should report this as a case of sputum smearnegativepulmonary tuberculosis to the MOH.Sputum smear positive TB case: The revised WHO definition of a new sputum smear positive pulmonaryTB case is based on the presence of at least one acid fast bacilli (AFB+) in at least one sputum sample incountries with a well functioning external quality assurance (EQA) systemTreatment failure: Failure of the prescribed drug regimen to eliminate the TB bacteria from the body. Thisis demonstrated by a lack of clinical improvement or by positive culture after the end of the fourth monthof treatmentTuberculosis: Active TB; disease due to infection with M. tuberculosis complexTuberculin skin test: A test which involves the injection of tuberculin (purified protein derivative, PPD)into the skin. An immune reaction can be assessed after a few days according to the size of induration atthe injection site. The test can demonstrate acquired immunity to TB, lack of immunity or possible currentinfection (a strong response) but are confounded by immunosuppression, prior BCG vaccine, serial TST andprior exposure to atypical mycobacteria. The results are generally referred to as positive or negative.-191-