Nosocomial transmission of the F15/LAM4/KZN genotype of Mycobacterium tuberculosis in patients on tuberculosis treatment

SETTING: King George V (KGV) Hospital has the largest tuberculosis (TB) facility in KwaZulu-Natal (KZN), the province with the highest prevalence of TB-HIV (human immunodeficiency virus) co-infection in South Africa. During the study, KGV was the only provincial referral hospital for patients with drug-resistant TB.OBJECTIVE: To determine the role of nosocomial transmission in patients infected with a new strain of Mycobacterium tuberculosis during treatment.DESIGN: Insertion sequence 6110-DNA fingerprinting was performed on stored isolates from patients with culture-positive pulmonary TB for more than 6 weeks after treatment started and those who relapsed.RESULTS AND CONCLUSION: DNA fingerprints of 14 of 26 patients with differing isolates matched those of other patients. Four of them acquired a F15/LAM4/KZN genotype, while two acquired fully susceptible Beijing strains. Three of the four F15/LAM4/KZN strains were multidrug-resistant with identical fingerprint patterns, while the fourth was fully susceptible. One of these was acquired during hospitalisation and three after discharge. Both HIV-infected and non-infected patients are at risk of infection with the F15/LAM4/KZN strain in health care facilities and within the community. Rapid diagnostic tests, separation of TB and non-TB patients on admission and isolation of multidrug-resistant and extensively drug-resistant TB patients are essential to curb nosocomial transmission.