Background & Objective: Tuberculosis is a diseases which is severely threatening the individuals health and is spreading quickly. Moreover, the appearance of new strains resistant to drugs has complicated the issue. Since there is no information available regarding the present drug-resistance situation of patients suffering from tuberculosis in Mashhad, this study was conducted to determine the prevalence of this resistance in this city.

 Methods: To determine prevalence of anti-tuberculosis drug resistance in Mashhad, drug sensitivity of 75 M. tuberculosis strains isolated from patients with pulmonary and extra-pulmonary tuberculosis from 20 Feb. 2002 to 20 Aug. 2002 was studied using the indirect proportion method. Every strain was tested against Rifampicin (RMP), Isoniazid (INH), Ethambutol (ETM), and Streptomycin (STM). Medical records of the patients were reviewed. Patients with no or less than 1 month treatment were defined as new cases and those previously treated for more than 1 month were defined as previously treated cases.

 Results: Of 75 isolates, 70(93.33%) were from new and 5(6.66%) from previously treated cases. 68 patients (90.66%) were suffering from pulmonary and 7(9.33%) from extra-pulmonary tuberculosis. Of 75 isolates, 23(36%) were resistant to at least one anti-tuberculosis drug. The highest rate of resistance was observed to streptomycin. Three of the 75 strains (4%) were resistant to all four drugs. 1.43% and 40% of strains isolated from newly and previously treated patients respectively were multidrug resistant.

 Conclusions: In this study new cases with MDR-TB were less prevalent compared to other studies. Most drug resistance and MDR-TB were associated with previous treatment. Continual evaluation of drug resistance following DOTS implementation seems to be necessary.

  Background & Objectives: Since 1985 because of increasing incidence of tuberculosis (TB) in HIV background, the outbreaks of TB have been reported in different parts of the world. From 1985 to 1991 the incidence of TB increased by 18% in United States and Europe. In Multi Drug Resistant outbreaks of TB in United States 18 to 35% of heath care workers (HCW) who had exposure to TB patients had PPD Converted to positive test (Seroconversion). That is why the risk of TB incidence in health care workers has been put forward again. This study was designed to determine the rate of Buali hospital HCW exposure to mycobacterium tuberculosis.

 Methods: All 96 HCW of Buali hospital took part in this cross-sectional and analytical study. No PPD test was performed for HCW in this hospital in the beginning of their employment. For this reason 30 officers who had not previously worked in hospital wards and 60 medical students who had not started their clinical course were selected to obtain an estimation of PPD test before starting professional nursing.

  Results: Out of 96 subjects, 72 were female and 24 were male. Rate of positive PPD was 50% in general. Data analysis showed that PPD positivity was in direct relationship with number of working years in hospital. In 60 university students whose mean age was 21.6± 0/2.9 PPD positivity rate was 13.3%. I the third group consisting of 30 office workers (mean age=333±6.5) it was 23.3%.

 Conclusion: This study shows that HCW with 50% of PPD positivity are in exceeding probability of mycobacterium tuberculosis exposure, which is almost twice as much as the other office workers, possibility of exposure.

  Background and Objective: Intradermal Purified Protein Derivative PPD test is a reliable test assessment of primary mycobacterial infection. In this test the specific antigen is Purified Protein Derivative (PPD). The reaction were assessed by touching, the induration's diameter after 48 &48hours. We compared the induration's size 48 and 72 hour in this study.

  Methods: At this semi experimental study a 5 unit PPD was administered to 120 healthy medical students.

  Results: The measurements made at 72 h were significantly (4.22 mm) (p<0.001) higher than those made at 48h (2.79 mm). The reading taken at 72 h were 1.47mm larger than at 48 h recovery. There were significant differences between induration size of 48 and 72h between male and female.

  Conclusion: This study demonstrates that, in adults, the size of the 5 U Monteux reaction is significantly larger at 72h compared to the reaction at 48h. We suggest to read PPD after 72 hours if the PPD is negative after 48 hours.

  Background & objectives : Amikacin is one of the key second-line drugs for treatment of tuberculosis. Mutations at the codons 1400, 1401and1483 of the 16srRNA gene are associated with resistance to amikacin. The purpose of this study was to detect these mutations using PCR-RFLP method in multi-drug resistant (MDR) strains of Mycobacterium tuberculosis showing resistance to amikacin.

  Methods : Susceptibility of strains (n=100) against first and second–line anti-tuberculosis drugs was performed by proportional method. Based on antimicrobial resistance pattern 97 strains were analyzed by PCR-RFLP method. rrs1096 and rrs1539 primers were used to amplify a 460bp region of the rrs gene. Then, the PCR products were digested using Tai 1 and Dde1 restriction enzymes. The results were analyzed by the SPSS software using Chi-square test.

  Results : Based on results from proportional method, 63 strains (64.9%) were MDR (Multiple Drug Resistant), 26 (26.8%) and 8 (8.2%) strains were susceptible and non-MDR, respectively. Also, 13.4% and 6.1% of the strains were XDR (Extensively Drug Resistant) and TDR ( Totally drug resistant ) respectively. Using PCR-RFLP method, 7 (7.2%) strains were resistant and 90 (92.7%) strains were susceptible to amikacin respectively. Moreover, we found that the mutation at the codon 1400 was the most frequent mutations responsible for resistance to amikacin.

  Conclusion : The PCR-RFLP method can be used as a supplemental method to detect resistance to amikacin however to increase our knowledge, mutatuions in several number of codons in rrs gene need to be studied.