ABSTRACT
Objective@#To evaluate the performence of GeneXpert MTB/RIF and BACTEC-MGIT 960 on detecting Mycobacterium tuberculosis and rifampicin resistance for pneumoconiosis-associated tuberculosis patients.@*Methods@#The recruited 133 suspected active pneumoconiosis-associated tuberculosis hospitalized cases, morning sputum samples were collected to do modified L-J culture, conventional proportion method drug susceptibility test, GeneXpert MTB/RIF and BACTEC-MGIT 960. Analyze the sensitivity and specificity of the 133 sputum from patients, the positive rates of patients with tuberculosis in GeneXpert MTB/RIF test, BACTEC-MGIT 960 and modified L-J culture were 37.59%, 34.59% and 30.08% respectively. There was no significant difference among the three tests respectively (P>0.05) . According to the modified L-J culture, the sensitivity of GeneXpert MTB/RIF and BACTEC-MGIT 960 in detecting tuberculosis were 92.5% and 95.0% respectively, and specificity in rifampicin resistance were 86.0% and 91.4% respectively. There was no significant difference between GeneXpert MTB/RIF and BACTEC-MGIT 960 (P>0.05) . According to conventional proportion method drug susceptibility test, the sensitivity of GeneXpert MTB/RIF and BACTEC-MGIT 960 in detecting rifampicin resistance were 90.0% and 100%, and specificity were 92.6% and 96.4%. There was no significant difference between GeneXpert MTB/RIF and BACTEC-MGIT 960 (P>0.05) .@*Conclusion@#The GeneXpert MTB/RIF has good performence of detecting tuberculosis and rifampicin resistance. It has good application value among pneumoconiosis-associated tuberculosis patients.
ABSTRACT
Genital tuberculosis is an important under-diagnosed factor of infertility. A vast majority of cases are asymptomatic and diagnosing them will help in treating such patients. We conducted a retrospective study in a tertiary care hospital of Delhi with an aim to compare different methods i.e., histopathological examination (HPE), acid-fast bacilli (AFB) smears, Lowenstein-Jensen (LJ) culture, BACTEC culture and polymerase chain reaction deoxyribonucleic acid (PCR-DNA) for diagnosing endometrial tuberculosis in infertile women. The data from 546 samples of endometrial biopsy histopathology, AFB smears and LJ culture was collected and then analyzed. Of these, HPE for tuberculosis was positive in 13, LJ culture in 10, AFB smear was positive in one case. BACTEC and PCR-DNA were feasible for 90 patients and PCR-DNA was positive in 20 and BACTEC in eight patients. Out of 20 patients with PCR positive results, 15 were only PCR positive and were subjected to hyster-laparoscopy and fi ve had evidence of tuberculosis. Thus, none of the available tests can pick up all cases of genital tuberculosis, but conventional methods i.e., histopathology and LJ culture still has an important role in the diagnosis of endometrial tuberculosis in government setups where BACTEC and PCR are not performed routinely due to lack of resources.
ABSTRACT
Background Traditionally, the Lowenstein Jensen (LJ) medium has been used for culturing Mycobacterium tuberculosis. In abdominal tuberculosis (TB), the reported yield from tissue culture is between 20% and 60%. Liquid cultures are reported to give a higher yield but there is little data available in abdominal TB. Aim To compare the yield of TB culture with BACTEC 460TB liquid medium and LJ medium for patients with suspected abdominal TB and determine cost effectiveness. Methods This prospective study was done in consecutive cases with clinical, radiological, endoscopic/surgical, and histological suspicion of abdominal TB. Tissue biopsies obtained at colonoscopy or surgery were processed and plated on LJ medium as well as the BACTEC 460TB system. NAP (ρ-nitro-α-acetylamino-β-hydroxy-propiophenone) differentiation was carried out to determine species. The cost of each method and cost per yield were calculated. Results Of the 29 cases, 22 cases (76%) were positive on BACTEC 460TB culture while 14 (48%) were positive on LJ medium giving a 64% increment in yield. However, the culture of one patient grew on LJ medium, where the BACTEC 460TB was negative. The additional cost of BACTEC 460TB is Rs. 460 and LJ is Rs. 40. Conclusions Samples from patients with abdominal TB should be processed on both liquid and LJ medium. For high yield, the use of a liquid culture medium system is essential.
ABSTRACT
BACKGROUND: Mycobacterial false-positive cultures have rarely been recognized in Korea, even though the rate of false-positive cultures of Mycobaterium tuberculosis has ranged from 0.4% to 4.0%. We estimated the false-positive rates by the review of medical records from whom mycobacterial cultures were requested, retrospeaively, after a bout of false-positive cultures was discovered in specimens treated in a single day. METHODS: Of the total 2,245 specimens, including 337 positive cultures of mycobacteria, during the period of January and June 1999, seventy-two specimens that showed colonies less than or equal to 5 colonies were reviewed, and classified as tuberculosis-likely group, tuberculosis-unlikely group and unclassifiable group by the clinical and radiological evidences, anti-tuberculosis therapy, and microbiological results. RESULTS: Tuberculosis-unlikely group was 21 specimens from 20 patients, and unclassifiable group was five specimens from four patients. So, the false-positive rates were estimated as 0.9- 1.1% of total cultures and 6.2-7.7% of positive cultures, according to excluding or including the unclassifiable group. CONCLUSION: Care should be taken for lowering false-positive mycobacterial cultures. Especially when a culture turned out to be positive with low colony isolates, more careful interpretations should be preceded before reporting the results by the review of medical records and communication with physician in charge.