MDR TB Transmission, Singapore

To the Editor: Over the past decade, the proportion of pulmonary multidrug-resistant tuberculosis (MDR TB) cases among Singapore-born patients remained low, whereas that among foreign-born patients was 10 times higher (1,2). Since 2005, Singapore has experienced a sharp increase in the number of MDR TB cases from high-prevalence countries (3). We report local transmission of MDR TB in 2011, from a short-stay visitor to 2 Singapore-born persons in a cor-rectional setting. The index case-patient was a 34-year-old Burmese man (patient A) arrested 10 months after entering Sin-gapore. A screening radiograph taken 2 days after arrest showed a right upper lobe cavitary lesion. The man was referred to the TB Control Unit. He had been coughing for 3 months but had no other concurrent conditions. When the abnormal radiograph results became known, the man was isolated within the prison. Sputum was collected , and first-line anti-TB drugs were administered pending sputum results. The sputum smear had 3+ acid-fast bacilli (AFB); mutations of the rpoB and katG genes were indicated by testing with GenoType MTDRplus (Hain Lifescience, Nehren, Germany). The patient's treatment regimen was modified accordingly; appropriate second-line anti-TB treatment was started 14 days after he entered the institution. Mycobacterium tuberculosis complex (MTC) grew from sputum in 9 days; phenotypic drug-susceptibility testing (DST) demonstrated resistance to rifampin, isoniazid, streptomycin, and ethambutol and susceptibility to pyra-zinamide, ethionamide, kanamycin, and ofloxacin. One month after patient A was arrested, a Singapore-born man (patient B) in a public hospital received a diagnosis of HIV infection (67 CD4 cells/mL) and Pneumocystis jirovecii pneumonia. He was not an identified contact of patient A, although his job entailed accompanying prisoners from remand centers to justice courts. An-tiretroviral treatment (ART) given 1 month after HIV diagnosis resulted in fever 7 days later. A repeat chest ra-diograph showed increased opacities in the left upper zone. Sputum smear was 4+ for AFB, and MTC with rpoB gene mutation was detected (Xpert MTB/RIF; Cepheid, Sunnyvale CA, USA). Second-line anti-TB drugs were administered. MTC was grown in sputum and blood in 14 and 32 days, respectively; phenotypic DST 8 weeks later showed a susceptibility profile that was identical (except for ethambutol susceptibility) to that of patient A. Patient C was a 43-year-old Singa-pore-born man arrested 1 month after receiving an HIV diagnosis and beginning ART. He withheld his HIV status from prison authorities. He shared a cell with patient A for ≈48 hours at …