BACKGROUND: Extensively drug-resistant (XDR) tuberculosis (TB) is a cause of concern, because it renders patients untreatable with available drugs. In this study, we documented the existence and transmission of XDR TB among patients with multidrug-resistant TB. These patients were referred to the National Research Institute of Tuberculosis and Lung Diseases (Tehran, Iran) for treatment and diagnosis from 2003 to 2005. METHODS: The sputum specimens from a total of 2030 patients with TB were digested, examined microscopically for acid-fast bacilli, and inoculated into Lowenstein-Jensen slants by standard procedures. Testing of susceptibility to first-line drugs was performed for 1284 Mycobacterium tuberculosis isolates. Subsequently, the strains that were identified as multidrug-resistant M. tuberculosis (113 isolates) were subjected to susceptibility testing for second-line drugs. Spoligotyping and restriction fragment-length polymorphism were performed for strains that were identified as XDR M. tuberculosis. RESULTS: A total of 12 (10.9%) of 113 multidrug-resistant M. tuberculosis strains were resistant to all 8 second-line drugs tested and, therefore, were denoted as XDR M. tuberculosis. Retrospective analysis of the cases of XDR TB showed that all of them belonged to 1 of 2 epidemiological clusters, either a single-family cluster (4 cases) or a cluster of close contacts (8 cases). The strains were identified as belonging to the M. tuberculosis superfamilies Haarlem 1 and East African Indian 3. CONCLUSIONS: The emergence of XDR TB cases in Iran highlights the need to reinforce the Iranian TB policy with regard to control and detection strategies.
BACKGROUND: Extensively drug-resistant (XDR) tuberculosis (TB) is a cause of concern, because it renders patients untreatable with available drugs. In this study, we documented the existence and transmission of XDR TB among patients with multidrug-resistant TB. These patients were referred to the National Research Institute of Tuberculosis and Lung Diseases (Tehran, Iran) for treatment and diagnosis from 2003 to 2005. METHODS: The sputum specimens from a total of 2030 patients with TB were digested, examined microscopically for acid-fast bacilli, and inoculated into Lowenstein-Jensen slants by standard procedures. Testing of susceptibility to first-line drugs was performed for 1284 Mycobacterium tuberculosis isolates. Subsequently, the strains that were identified as multidrug-resistant M. tuberculosis (113 isolates) were subjected to susceptibility testing for second-line drugs. Spoligotyping and restriction fragment-length polymorphism were performed for strains that were identified as XDR M. tuberculosis. RESULTS: A total of 12 (10.9%) of 113 multidrug-resistant M. tuberculosis strains were resistant to all 8 second-line drugs tested and, therefore, were denoted as XDR M. tuberculosis. Retrospective analysis of the cases of XDR TB showed that all of them belonged to 1 of 2 epidemiological clusters, either a single-family cluster (4 cases) or a cluster of close contacts (8 cases). The strains were identified as belonging to the M. tuberculosis superfamilies Haarlem 1 and East African Indian 3. CONCLUSIONS: The emergence of XDR TB cases in Iran highlights the need to reinforce the Iranian TB policy with regard to control and detection strategies.
Authors: Carole D Mitnick; Sonya S Shin; Kwonjune J Seung; Michael L Rich; Sidney S Atwood; Jennifer J Furin; Garrett M Fitzmaurice; Felix A Alcantara Viru; Sasha C Appleton; Jaime N Bayona; Cesar A Bonilla; Katiuska Chalco; Sharon Choi; Molly F Franke; Hamish S F Fraser; Dalia Guerra; Rocio M Hurtado; Darius Jazayeri; Keith Joseph; Karim Llaro; Lorena Mestanza; Joia S Mukherjee; Maribel Muñoz; Eda Palacios; Epifanio Sanchez; Alexander Sloutsky; Mercedes C Becerra Journal: N Engl J Med Date: 2008-08-07 Impact factor: 91.245