Case 1
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Rule out disease: Obtain specimens before starting therapy. This is a highly significant Mantoux reaction.
Three gastric aspirates were obtained, as an outpatient, on successive mornings. All were immediately placed in a buffered kit containing sodium carbonate. All were smear negative. Following the third test, treatment for tuberculosis (TB) disease was commenced using isoniazid (INH), rifampin, pyrazinamide and ethambutol (at a dose of 15 mg/kg/day). The third aspirate grew Mycobacterium tuberculosis after two weeks. A repeat chest x-ray at that time showed a left lower lobe infiltrate. Ethambutol was discontinued after the strain was reported to be sensitive to all first line agents. INH, rifampin and pyrazinamide were given for two months and INH and rifampin were contined for a further four months. The child’s energy improved within a few days and he is clinically well and cured.
Identify the source: The patient’s Grandmother in Kenya was identified as having active pulmonary TB.
Case 2
Principle: Make every effort to establish the contact strain. A history taken through a Burmese translator (obtained through a telephone translation service) revealed the identity of the TB contact, the child’s caregiver. It was then established that the contact’s strain of M tuberculosis was resistant to INH, rifampin, ethambutol and ethionamide and sensitive to pyrazinamide and second line agents. A computed tomography scan of the chest, obtained to help rule out TB disease conclusively, was normal.
This child is likely infected with a highly resistant strain. Like all latently infected children she is at risk for active disease. After consultation with several experts, directly observed preventive therapy with ciprofloxacin and pyrazinamide was commenced and was well tolerated: we plan on 12 months of therapy. An alternative approach is to follow this child closely, reserving drugs for disease if it develops.
Case 3
Although the Bacille Calmette-Guerin is a possible cause of a false positive reaction, it is much more likely that the reaction is due to latent TB infection. The child comes from a country with a high prevalence of TB. Her birth circumstances were unknown and may have been in an especially high risk environment. If she is latently infected she has a 20% to 40% chance of developing TB disease. The highest risk is in the next few years, and up to 40% of this will be extrapulmonary, including TB meningitis.
Complications of INH at this age are rare, and can usually be predicted from side effects. The benefit to risk ratio in this situation is strongly in favour of treatment. Treatment with INH for nine months should be strongly advised. The child should be seen monthly to monitor side effects. If any anorexia, nausea or jaundice occurs, the INH should be withheld and liver function tests should be checked.
Case 4
Again, obtain specimens. Ideally this patient should be hospitalized and isolated until the diagnosis is clear. However, sputum should be submitted for direct smear, TB culture and a rapid test for TB as soon as possible. Her sputum was smear numerous and AMTD positive, immediately confirming the diagnosis of pulmonary TB. In similar cases, adolescents have received multiple courses of antibiotics before the diagnosis of pulmonary TB was established, and have infected several classmates. Although reactivation disease typically occurs in the upper lobes, any combination of airspace disease in the right epidemiological setting is potentially due to TB.
