Abstract

BackgroundRelapse of tuberculosis (TB) may develop as the result of reactivation of the endogenous primary infection, or as a result of a exogenous reinfection. This survey evaluated the rate of reactivation versus recent transmission among Iranian and Afghan relapse cases.MethodsThe sputum specimens were digested, examined microscopically for acid-fast bacilli, and inoculated into Löwenstein-Jensen slants by standard procedures. Thereafter, the susceptibility and identification tests were performed on culture positive specimens. Subsequently, the strains that were identified as Mycobacterium tuberculosis (258 isolates) were subjected to IS6110 restriction fragment length polymorphism (RFLP) and spoligotyping. Additional patient's information was collected for further epidemiological analysis. Patients whose isolates had identical genotyping patterns were considered a cluster with recent transmission episode.ResultsOut of 258 available isolates, 72(28%) had multi-drug resistant (MDR-TB) in ratio and 42 (16.2%) had other resistant. Notably, 38 of MDR-TB cases (52%) were isolated from Afghan patients. By IS6110-RFLP typing method, 65 patients (25%) were clustered in 29 clusters. In cluster cases, the intra-community transmissions between Iranian and Afghan patients were 41%. All MDR-TB patients in clusters had either Haarlem I or Beijing characteristic. The risk factors like sex, family history, close contact, living condition, PPD test result and site of TB infection were not associated with clustering. Although, the MDR-TB strains were more frequent in non-cluster cases (31%) than cluster one(18%) (P < 0.05). Majority of M. tuberculosis strains isolated from non-cluster cases were belong to EAI3 (51; 30%) and CASI(32;18.6%) superfamilies.ConclusionDuring the studied period, reactivation of a previous infection remain the more probable cause of recurrence. Although, the evidence of intra- community transmission between Iranian and Afghan TB cases, highlighted the impact of afghan immigrants in national tuberculosis control program (NTP) of Iran.

Highlights

  • Relapse of tuberculosis (TB) may develop as the result of reactivation of the endogenous primary infection, or as a result of a exogenous reinfection

  • Restriction fragment length polymorphism (RFLP) using insertion sequence IS6110 is a well-established method of "DNA fingerprinting" that has been used to trace the transmission of particular strains of M. tuberculosis isolates [1,2]

  • Considering the severity of diseases associated with spread and transmission of MDR or XDR-TB strains, we tried to determine the relative frequency of reactivation from recent transmission among relapse cases using IS6110-RFLP

Read more

Summary

Introduction

Relapse of tuberculosis (TB) may develop as the result of reactivation of the endogenous primary infection, or as a result of a exogenous reinfection. This survey evaluated the rate of reactivation versus recent transmission among Iranian and Afghan relapse cases. By IS6110-RFLP, it was possible to determine whether a new episode of disease is caused by reactivation of endogenous infection or by exogenous reinfection [6,7]. Considering the severity of diseases associated with spread and transmission of MDR or XDR-TB strains, we tried to determine the relative frequency of reactivation from recent transmission among relapse cases using IS6110-RFLP. The contribution of Afghan immigrants in maintaining the recurrent tuberculosis was determined

Methods
Results
Discussion
Conclusion

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.