Multidrug Resistant Tuberculosis: Closer to Home Than You May Think

Abstract

INTRODUCTION: Primary multidrug resistant tuberculosis (MDR-TB) is defined as tuberculosis resistant to both isoniazid and rifampicin in a patient with no previous history of tuberculosis (TB). According to the Centers for Disease Control (CDC), there were 14 cases of MDR-TB in United States (US)-borne persons in the US in 2010. CASE PRESENTATION: A 68-year-old man presented with complaint of a dry cough with occasional sputum production, fatigue, and malaise for the past year. Patient had a history of asthma and gastroesophageal reflux disease. He lived in rural Pennsylvania, denied ever smoking, being in prison or the military. He did have an extensive travel history within the United States, Canada, and Western Europe. Physical exam did not reveal wheezes, rhonchi, or rales. Imaging of the chest revealed patchy tree-in-bud appearance with peribronchovascular nodularity. Acid-fast bacillus (AFB) culture grew Mycobacterium tuberculosis(M. tuberculosis). Patient was started on rifampicin (RMP), isoniazid (INH), ethambutol (EMB), and pyrazinamide (PZA). Drug sensitivities later indicated the patient was resistant to INH, RMP, and PZA. EMB was continued and patient was started on capreomycin, cycloserine, para-aminosalicylic acid, and moxifloxacin. Within 3 weeks, AFB cultures converted to negative. Patient is currently continuing with multi-drug treatment to complete a total of 18 months post conversion to negative cultures. DISCUSSION: MDR-TB is more common among foreign-borne persons in the US and those with prior treatment for TB. The highest proportion of MDR-TB is found in the former Soviet Union and China, with the majority of new cases in China and India. Because of the slow growth of M. tuberculosis, drug sensitivity by culture takes 4 to 8 weeks. Molecular detection of drug resistance (MDDR) can reveal sensitivities in one to two days. Currently, MDDR testing is only available under certain circumstances: high-risk (previous TB, MDR-TB exposure, foreign-borne), high-profile (nurse, daycare worker), known RMP resistance, and on a case-by-case basis. However, as we have presented a case of MDR-TB in a US-borne patient in central Pennsylvania with no identifiable risk factors for TB or drug-resistance, there is an increased need for MDDR testing. CONCLUSIONS: Universal testing with MDDR can provide earlier identification of MDR-TB in patients similar to the case presented. With early detection of MDR-TB, we can potentially reduce time of contagiousness, incidence of MDR-TB cases, morbidity/mortality, and health care costs.