Born in Italy, a 23-month-old girl presented to a clinic with fever lasting for a three-week period, despite previous antibiotic treatment. She lived with an aunt who was diagnosed and treated for tuberculosis (TB) with second-line antibiotics. Although the child had no cough or pulmonary symptoms, a tuberculin skin test was positive. Also, a chest x-ray revealed a left, perihilar infiltrate in the lung.
Although she was acid-fast bacillus (AFB) smear negative, nucleic acid amplification testing (NAAT) of three gastric aspirates were positive, identifying M. tuberculosis. Because physicians suspected drug resistance, she was started on the combined therapy of isoniazid (INH), rifampin (RIF), pyrazinamide (PZA), streptomycin, and ciprofloxacin (CIPRO), pending culture and susceptibility testing.
A few weeks later, a sputum culture and susceptibility test from the aunt proved her strain was resistant to all first-line antibiotics. Susceptibility testing to second-line drugs revealed resistance to kanamycin, but susceptibility to ethionamide (ETH), moxifloxacin (M0X), p-aminosalicylic acid (PAS), and linezolid (LNZ).
Based on results of the aunt’s susceptibility test demonstrating multidrug-resistant TB (MDR-TB), and assuming they had similar strains, therapy was adjusted for the aunt and the child, reflecting the recent susceptibility pattern. New combined treatment was started with ETH, PAS, MOX, and LNZ, stopping ETH and PAS after two months for the aunt and five months for the child, but continuing the MOX and LNZ for a total of 13 months. Because second-line drugs were not officially approved for use in children (due to adverse side effects), the treatment was administered at the hospital for three months, then on an outpatient basis for the duration. Both patients were culture negative after one month from the initiation of the second-line drugs. Chest x-rays showed no infiltrates, and no adverse drug reactions were observed. Blood test evaluations of liver and kidney function were normal on a monthly basis, thereafter, as were routine eye and EKG exams. The child had no signs of relapse 18 months later.