Background： Direct ZN （Ziehl-Neelsen） sputum smear microscopy for diagnosis of TB （tuberculosis） has low sensitivity, especially in TB/HIV co-infected patients. Sputum concentration by bleach （NaOCI） with sedim...Background： Direct ZN （Ziehl-Neelsen） sputum smear microscopy for diagnosis of TB （tuberculosis） has low sensitivity, especially in TB/HIV co-infected patients. Sputum concentration by bleach （NaOCI） with sedimentation has been used to increase the sensitivity of sputum smear microscopy in many settings but with varying results. Objective： To determine whether bleach plus centrifugation significantly improves the detection of AFB （acid-fast bacilli） in ZN smear-negative sputum specimens. Methods： Three hundred and seventy sputum specimens were collected from new TB suspects attending a Nairobi referral district hospital and processed for direct microscopy using ZN technique and culture on Lowenstein Jensen Media. All smear-negative specimens were treated with 3.5% bleach and left to stand for 30 min before centrifugation. The bleach treated smears were processed and examined using ZN technique. Results： Of the 370 specimens, 200 （54%） were positive culture. The number of sputum samples that were smear-positive by direct ZN was 138 （37.2%）, with a sensitivity of 66%. After treatment of direct ZN smear-negative specimens with 3.5% bleach and centrifugation, the total number of AFB smear-positive samples increased to 171 with an increase in sensitivity of 66% to 81.1% （15.1%）. Conclusion： In this study, bleach with centrifugation significantly increased the yield of sputum smear microscopy. Further evaluation of these techniques in routine programmes is required especially in settings where the burden of TB/HIV is high.展开更多
Background The epidemiological characteristics of drug-resistant tuberculosis （DR-TB） is fundamental to improving the prevention and control of DR-TB. Mutations in katG315 is thought to be the most predictive molecu...Background The epidemiological characteristics of drug-resistant tuberculosis （DR-TB） is fundamental to improving the prevention and control of DR-TB. Mutations in katG315 is thought to be the most predictive molecule markers for Isoniazid （INH） resistance in Mycobacterium tuberculosis （MTB）. However, mutations to these genes have not been thoroughly studied in China, and epidemiological evidence of their expression levels are especially lacking in the southwest of China, which has a high TB burden within the population. Methods MTB isolates were obtained from patients with active pulmonary tuberculosis at the TB dispensary and Chest hospital in Chongqing city between June 2003 and June 2006. Proportion methods were used to test the sensitivity to INH, RFP, SM and EMB of cultured MTB. A total of 100 MTB isolates were also randomly selected for analysis of the molecular mutation spectrum of katG by DNA sequencing. Results Totally 1 089 MTB isolates that completed positive sputum cultures and evaluated for their sensitivity to the four first-line drugs among 2 777 patients with TB. The prevalence of DR-TB and multi-drug resistant tuberculosis （MDR-TB） were 27.7% （302/1 089） and 7.3% （79/1 089）, respectively. The resistance to anti-TB drugs was found to be highest for SM （16.3%） and INH （14.0%）. There was also a significant increase in the prevalence of resistance to RFP and EMB （P〈0.01）, and an increase in MDR-TB between June 2003 and June 2004 and between July 2005 and June 2006. The total mutation rate of katG315 was 75＂5% （37/49） in INH-resistant MTB, and mutation sites included $315T, $315N and $315I with mutation rates of 81.1% （30/37）, 13.5% （5/37） and 5.4% （2/37）, respectively No katG315 mutants were found in any of the 48 INH-sensitive MTB. Our preliminary diagnostic results suggest that mutations in katG315 may potentially serve as molecular markers that can be used to diagnose the resistance to anti-TB drug of INH. Conclusion In the Chongqing, DR-TB and MDR-TB are increasing, and are becoming key problems for tuberculosis control. The use of katG315 mutations as potential molecule markers for drug resistance to INH may help improve patient treatment and decrease the spread of the disease展开更多
文摘Background： Direct ZN （Ziehl-Neelsen） sputum smear microscopy for diagnosis of TB （tuberculosis） has low sensitivity, especially in TB/HIV co-infected patients. Sputum concentration by bleach （NaOCI） with sedimentation has been used to increase the sensitivity of sputum smear microscopy in many settings but with varying results. Objective： To determine whether bleach plus centrifugation significantly improves the detection of AFB （acid-fast bacilli） in ZN smear-negative sputum specimens. Methods： Three hundred and seventy sputum specimens were collected from new TB suspects attending a Nairobi referral district hospital and processed for direct microscopy using ZN technique and culture on Lowenstein Jensen Media. All smear-negative specimens were treated with 3.5% bleach and left to stand for 30 min before centrifugation. The bleach treated smears were processed and examined using ZN technique. Results： Of the 370 specimens, 200 （54%） were positive culture. The number of sputum samples that were smear-positive by direct ZN was 138 （37.2%）, with a sensitivity of 66%. After treatment of direct ZN smear-negative specimens with 3.5% bleach and centrifugation, the total number of AFB smear-positive samples increased to 171 with an increase in sensitivity of 66% to 81.1% （15.1%）. Conclusion： In this study, bleach with centrifugation significantly increased the yield of sputum smear microscopy. Further evaluation of these techniques in routine programmes is required especially in settings where the burden of TB/HIV is high.
基金Supported by the National Natural Science Foundation of China(30700685)the Medical Science and Technology Research Project of Chongqing Municipal Health Bureau(2009-1-06)
文摘Background The epidemiological characteristics of drug-resistant tuberculosis （DR-TB） is fundamental to improving the prevention and control of DR-TB. Mutations in katG315 is thought to be the most predictive molecule markers for Isoniazid （INH） resistance in Mycobacterium tuberculosis （MTB）. However, mutations to these genes have not been thoroughly studied in China, and epidemiological evidence of their expression levels are especially lacking in the southwest of China, which has a high TB burden within the population. Methods MTB isolates were obtained from patients with active pulmonary tuberculosis at the TB dispensary and Chest hospital in Chongqing city between June 2003 and June 2006. Proportion methods were used to test the sensitivity to INH, RFP, SM and EMB of cultured MTB. A total of 100 MTB isolates were also randomly selected for analysis of the molecular mutation spectrum of katG by DNA sequencing. Results Totally 1 089 MTB isolates that completed positive sputum cultures and evaluated for their sensitivity to the four first-line drugs among 2 777 patients with TB. The prevalence of DR-TB and multi-drug resistant tuberculosis （MDR-TB） were 27.7% （302/1 089） and 7.3% （79/1 089）, respectively. The resistance to anti-TB drugs was found to be highest for SM （16.3%） and INH （14.0%）. There was also a significant increase in the prevalence of resistance to RFP and EMB （P〈0.01）, and an increase in MDR-TB between June 2003 and June 2004 and between July 2005 and June 2006. The total mutation rate of katG315 was 75＂5% （37/49） in INH-resistant MTB, and mutation sites included $315T, $315N and $315I with mutation rates of 81.1% （30/37）, 13.5% （5/37） and 5.4% （2/37）, respectively No katG315 mutants were found in any of the 48 INH-sensitive MTB. Our preliminary diagnostic results suggest that mutations in katG315 may potentially serve as molecular markers that can be used to diagnose the resistance to anti-TB drug of INH. Conclusion In the Chongqing, DR-TB and MDR-TB are increasing, and are becoming key problems for tuberculosis control. The use of katG315 mutations as potential molecule markers for drug resistance to INH may help improve patient treatment and decrease the spread of the disease
