Chest
Volume 136, Issue 2, August 2009, Pages 420-425
Journal home page for Chest

Original Research
Tuberculosis
Emergence of New Forms of Totally Drug-Resistant Tuberculosis Bacilli: Super Extensively Drug-Resistant Tuberculosis or Totally Drug-Resistant Strains in Iran

https://doi.org/10.1378/chest.08-2427Get rights and content

Background

The study documented the emergence of new forms of resistant bacilli (totally drug-resistant [TDR] or super extensively drug-resistant [XDR] tuberculosis [TB] strains) among patients with multidrug-resistant TB (MDR-TB).

Methods

Susceptibility testing against first- and second-line drugs was performed on isolated Mycobacterium tuberculosis strains. Subsequently, the strains identified as XDR or TDR M tuberculosis were subjected to spoligotyping and variable numbers of tandem repeats (VNTR).

Results

Of 146 MDR-TB strains, 8 XDR isolates (5.4%) and 15 TDR isolates (10.3%) were identified. The remaining strains were either susceptible (67%) or had other resistant patterns (20%). Overall, the median of treatments and drugs previously received by MDR-TB patients was two courses of therapy of 15 months' duration with five drugs (isoniazid [INH], rifampicin [RF], streptomycin, ethambutol, and pyrazinamide). The median of in vitro drug resistance for all studied cases was INH and RF. The XDR or TDR strains were collected from both immigrants (Afghan, 30.4%; Azerbaijani, 8.6%; Iraqi, 4.3%) and Iranian (56.5%) MDR-TB cases. In such cases, the smear and cultures remained positive after 18 months of medium treatment with second-line drugs (ethionamide, para-aminosalicylic acid, cycloserine, ofloxacin, amikacin, and ciprofloxacin). Spoligotyping revealed Haarlem (39.1%), Beijing (21.7%), EAI (21.7%), and CAS (17.3%) superfamilies of M tuberculosis. These superfamilies had different VNTR profiles, which eliminated the recent transmission among MDR-TB cases.

Conclusions

The isolation of TDR strains from MDR-TB patients from different regional countries is alarming and underlines the possible dissemination of such strains in Asian countries. Now the next question is how one should control and treat such cases.

Section snippets

Setting

The National Research Institute of Tuberculosis and Lung Diseases (NRITLD) (Tehran, Iran) acts as the sole national referral center for TB in Iran. Located inside the NRILTD is a National Reference Tuberculosis Laboratory, which is under the technical supervision of the Supranational Reference Laboratories of the Swedish Institute for Infectious Diseases Control (Solna, Sweden). Under the National Tuberculosis Control program, all the MDR and relapse cases of TB are referred to the NRITLD for

Study Population

From October 2006 to October 2008, 166 MDR-TB patients were referred to the NRITLD for treatment and diagnosis. Of these patients, 20 patients (12%) had infection with mycobacterium other than tuberculosis. The results of susceptibility against first-line drugs were improved resistance to INH and RF in the remaining MTB isolates (n = 146). The results of susceptibility against second-line drugs were as follows: 65 strains (44.5%) were susceptible to all drugs tested, 8 strains were XDR (5.4%),

Discussion

This study represents the first report on the existence and prevalence of TDR strains in Iran. TDR strains not only constitute a deadly threat to the affected patients with TB but also hamper the TB-control program. Previously, we identified two clusters of XDR-TB isolates in both family and community outbreaks.2 These strains were fully capable of being transmitted and causing active diseases in individuals with secondary cases. In the present report, 95% of XDR and TDR strains were isolated

Acknowledgments

Author contributions: Drs. Velayati and Masjedi participated in the study conception and manuscript review. Dr. Farnia designed and implemented the study, and wrote the manuscript. Drs. Tabarsi, Ghanavi, ZiaZarifi, and Hoffner reviewed the data and manuscript.

Financial/nonfinancial disclosures: The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Other contributions: We

References (0)

Cited by (494)

  • Active tuberculosis of spine: Current updates

    2023, North American Spine Society Journal
  • Evolutionary history and phylogeography of the MTBC complex

    2023, Bulletin de l'Academie Nationale de Medecine
View all citing articles on Scopus

Funding/Support: This research was funded by the Medical Research Council/National Research Institute of Tuberculosis and Lung Disease/World Health Organization grant No. 0116-28–2006.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (www.chestjournal.org/site/misc/reprints.xhtml).

View full text