Inferring Mycobacterium Tuberculosis Drug Resistance and Transmission using Whole-genome Sequencing in a High TB-burden Setting in China

Objective China is among the 30 countries with a high burden of tuberculosis(TB)worldwide,and TB remains a public health concern.Kashgar Prefecture in the southern Xinjiang Autonomous Region is considered as one of the highest TB burden regions in China.However,molecular epidemiological studies of Kashgar are lacking.Methods A population-based retrospective study was conducted using whole-genome sequencing(WGS)to determine the characteristics of drug resistance and the transmission patterns.Results A total of 1,668 isolates collected in 2020 were classified into lineages 2(46.0%),3(27.5%),and 4(26.5%).The drug resistance rates revealed by WGS showed that the top three drugs in terms of the resistance rate were isoniazid(7.4%,124/1,668),streptomycin(6.0%,100/1,668),and rifampicin(3.3%,55/1,668).The rate of rifampicin resistance was 1.8%(23/1,290)in the new cases and 9.4%(32/340)in the previously treated cases.Known resistance mutations were detected more frequently in lineage 2 strains than in lineage 3 or 4 strains,respectively:18.6%vs.8.7 or 9%,P<0.001.The estimated proportion of recent transmissions was 25.9%(432/1,668).Multivariate logistic analyses indicated that sex,age,occupation,lineage,and drug resistance were the risk factors for recent transmission.Despite the low rate of drug resistance,drug-resistant strains had a higher risk of recent transmission than the susceptible strains(adjusted odds ratio,1.414;95%CI,1.023–1.954;P=0.036).Among all patients with drug-resistant tuberculosis(DR-TB),78.4%(171/218)were attributed to the transmission of DR-TB strains.Conclusion Our results suggest that drug-resistant strains are more transmissible than susceptible strains and that transmission is the major driving force of the current DR-TB epidemic in Kashgar.

Molecular Identification of Mycobacterium Strains Responsible of Bovine Tuberculosis Cases in Bobo-Dioulasso Slaughterhouse, Burkina Faso

Bovine tuberculosis (bTB) is an endemic zoonosis significantly affects animal health in Burkina Faso. The primary causative agent is Mycobacterium tuberculosis (M. tuberculosis) complex, mainly M. bovis. Cattle are considered as natural reservoir of M. bovis. However, in Burkina Faso, the circulation of these strains remains poorly understood and documented. This study aimed to identify and characterize Mycobacterium strains from suspected carcasses during routine meat inspection at Bobo-Dioulasso refrigerated slaughterhouse. A prospective cross-sectional study was conducted from January 2021 to December 2022 on cases of seizures linked to suspected bovine tuberculosis. Microbiological and molecular analyzes were used for mycobacterial strain isolation and characterization. Out of 50 samples, 24% tested positive by microscopy and 12% by culture. Molecular analysis identified 6 strains of Mycobacteria, exclusively Mycobacterium bovis specifically the subspecies bovis (Mycobacterium bovis subsp bovis). In conclusion, M. bovis subsp bovis is the primary agent responsible for bovine tuberculosis in Bobo-Dioulasso. Continuous monitoring of mycobacterial strains is therefore necessary for the effective control of this pathology in the local cattle population.

Tuberculosis in the Carcinal Environment in Chad Due to the Mycobacterium Tuberculosis Circulante Complex

Tuberculosis (TB) is a serious infectious disease and its control is considered a challenge, particularly among vulnerable populations such as prisoners. The prevalence of TB in prisons is an alarming public health problem in many countries. The aim of this study is to describe the epidemiology of tuberculosis and the strategies for controlling this disease in the Chadian prison population. During the course of our study, the prevalence of tuberculosis in prisons was 9.64%. The age group between 55 years and over (43.33%) was the most represented in this study, and all patients were men with a frequency of 62.66%. The cross-tabulation of Culture_7H9G and Culture_7H9P showed that out of our total positive sample, we found a total of 87 positive strains and 63 negative strains. Our study shows that it is essential to know the prevalence of tuberculosis in all the country’s prisons. Indeed, this can serve as an indication of the need for action in prisons to reduce TB rates, in particular by improving the structure of prison environments, diagnosing new cases quickly and accurately, identifying drug-resistant strains and implementing effective, direct treatment observed in people with tuberculosis.

Early Prosthetic Valve Endocarditis with Mycobacterium Tuberculosis after Mitral Valve Replacement: A Case Report

Background: Tuberculous endocarditis is a rare but serious complication of heart valve replacement surgery. We report the case of a 24-year-old patient, who presented with tuberculous endocarditis after mechanical mitral valve replacement, with a favorable clinical course following anti-tuberculosis treatment. Case Presentation: We report a 24-year-old male patient, admitted to the cardiac surgery department of the Fann Hospital (Dakar, Senegal), for the management of severe mixed (rheumatic and endocarditic) mitral insufficiency with associated tricuspid insufficiency. He had a history of recurrent angina and polyarthralgia in childhood, was hospitalized several times for refractory global cardiac decompensation, and for a suspected infective endocarditis a month before his admission. On admission, the clinical examination revealed signs suggestive of mitral and tricuspid insufficiency. Transthoracic echocardiography revealed severe post-endocarditic mitral insufficiency with A3 amputation, highly mobile 15 mm vegetations on the free edge of the large valve, moderate tricuspid insufficiency, and severe pulmonary artery hypertension. Mechanical mitral valve replacement and tricuspid valve annuloplasty using autologous pericardial strip were performed via median sternotomy. After ten days, the patient presented with global cardiac decompensation associated with a clinico-biological infectious syndrome, and tans-oesophageal echography revealed an abscess at the sinotubular junction, communicating with the aorta. A thoraco-abdomino-pelvic CT scan was done, which revealed a bilateral alveolar-interstitial syndrome with mediastinal lymphadenopathy. Anti-tuberculosis treatment with RHZE was initiated for 06 months. The clinical course was favorable. Conclusion: Tuberculous endocarditis in prostheses is a serious complication of heart valve replacement surgery, which may evolve favorably under medical treatment.

Mutation Characteristics of inhA and katG Genes in Isoniazid-Resistant Mycobacterium Tuberculosis Patients in Xinjiang

Objective:To analyze the mutation characteristics of inhA and katG genes in isoniazid-resistant Mycobacterium tuberculosis in Xinjiang.Methods:The katG and inhA in 148 strains of isoniazid-resistant Mycobacterium tuberculosis were amplified through fluorescence quantitative PCR,and the amplified products were sequenced and compared.Results:The inhA gene mutation rate of 148 strains of isoniazid-resistant mycobacterium tuberculosis was 13.51%(20/148),among which the inhA gene mutation rate among patients of Han,Uygur,and Kazakh ethnicity were 15.87%,13.21%,and 17.65%,respectively.There was no significant difference in the inhA mutation rate among nationalities(c^(2)=2.897,P>0.05).The mutation rate of the katG gene was 84.46%(125/148),among which the mutation rates of patients of Han,Uyghur,and Kazak ethnicities were 82.54%,84.91%,and 76.47%,respectively.The Hui and other ethnic groups were all affected by the katG gene mutation.There was no significant difference in the mutation rate of the katG gene among different ethnicities(c^(2)=3.772,P>0.05).The mutation rates of the inhA gene in southern Xinjiang,northern Xinjiang,and other provinces were 18.60%,9.28%,and 37.50%,respectively.The mutation rates of the inhA gene in different regions were statistically different(c^(2)=6.381,P<0.05).There was no significant difference in the inhA mutation rate between patients from southern and northern Xinjiang(c^(2)=2.214,P>0.05)and between southern Xinjiang and other provinces(c^(2)=1.424,P>0.05).However,the mutation rate of the inhA gene in patients from other provinces was higher than that in northern Xinjiang(c^(2)=5.539,P<0.05).The mutation rates of the katG gene in southern Xinjiang,northern Xinjiang,and other provinces were 81.40%,87.63%,and 62.50%,respectively.There was no significant difference in the mutation rates of the katG gene among different regions(c^(2)=3.989,P>0.05).Conclusion:katG gene mutation was predominant in isoniazid-resistant tuberculosis patients in Xinjiang Uygur Autonomous Region,and inhA and katG gene mutation were no different among different ethnic groups.

Value of ultrasound guided biopsy combined with Xpert Mycobacterium tuberculosis/resistance to rifampin assay in the diagnosis of chest wall tuberculosis

BACKGROUND The thoracic wall lesions,particularly chest wall tuberculosis,and chest wall tumors and other pyogenic wall and actinomycetes infections,almost always present as a diagnostic challenge.AIM To explore the value of ultrasound-guided biopsy combined with the Xpert Mycobacterium tuberculosis/resistance to rifampin(MTB/RIF)assay to diagnose chest wall tuberculosis.METHODS We performed a retrospective study of patients with chest wall lesions from March 2018 to March 2021.All patients received the ultrasound-guided biopsy for pathology examination,acid-fast Bacillus staining,mycobacterial culture,and Xpert MTB/RIF analysis.The sensitivity,specificity,and area under the curve(AUC)were calculated for these diagnostic tests,either individually or combined.Rifampicin resistance results were compared between the mycobacterial culture and the Xpert MTB/RIF assay.RESULTS In 31 patients with the chest wall lesion biopsy,22 patients were diagnosed with chest wall tuberculosis.Of them,3,6,and 21 patients tested positive for mycobacterial culture,acid-fast stain,and Xpert MTB/RIF assay,respectively.The rifampicin resistance results of the 3 culture-positive patients were consistent with their Xpert MTB/RIF assay results.When considering the sensitivity,specificity,and AUC value,the Xpert MTB/RIF assay(95.5%,88.9%,and 0.92,respectively)was a better choice than the acid-fast Bacillus stain(27.3%,100.0%,and 0.64,respectively)and mycobacterial culture(13.6%,100.0%,0.57,respectively).No complications were reported during the procedure.CONCLUSION Ultrasound guided biopsy combined with Xpert MTB/RIF has high value in the diagnosis of chest wall tuberculosis,and can also detect rifampicin resistance.

Research progress on the drug action and resistance mechanism in Mycobacterium tuberculosis

Tuberculosis(TB)is a chronic infectious disease caused by Mycobacterium Tuberculosis(MTB).It is the second largest single cause of death besides novel coronavirus pneumonia.Along with the abuse of antibiotics and extensive use of anti-tuberculosis drugs,multidrug-resistant(MDR)TB,drug-resistant(XDR)TB and totally drug-resistant(TDR)TB became obstacles to the tuberculosis eradication worldwide.According to the World Health Organization(WHO)statistics,China is not only a high burden tuberculosis country in the world,but also a country with a serious epidemic of MDR.Traditional drugs fail to meet the needs of tuberculosis control.Therefore,it is urgent to find new targets of anti-tuberculosis drugs and develop new anti-tuberculosis drugs.Hence,this paper systematically summarizes the mechanism of traditional and newly developed anti-tuberculosis drugs,in which stressing the research progress of drug resistance mechanisms.This work provides us with new insights of new anti-tuberculosis drug developments,and may contribute to a reduction in the harm that tuberculosis brings to society.

Analysis of The Correlation Between inhA Gene Mutation and Resistance to Protionamide in Drug-Resistant Mycobacterium Tuberculosis

Objective: To investigate the characteristics of katG and inhA gene mutations in multidrug-resistant tuberculosis (MDR-TB), pre-extensively drug-resistant tuberculosis (preXDR-TB), and their correlation with resistance to protionamide (Pto). Methods: A total of 229 patients with MDR-TB and pre-XDR-TB diagnosed in the Eighth Affiliated Hospital of Xinjiang Medical University from January 2020 to February 2024 were selected to analyze the characteristics of katG and inhA mutations in MTB clinical isolates and their correlation with Pto resistance. Results: The mutation rate of katG (with or without inhA mutation) was 85.2%. The mutation rates in MDR-TB and pre-XDR-TB were 87.4% (125/143) and 81.4% (70/86), respectively. The mutation rate of inhA (including katG mutation) was 14.8% (34/229), which was 12.6% (18/143) and 18.6% (16/86) in MDR-TB and pre-XDR-MTB, respectively. There was no difference in mutation (P > 0.05). Conclusion: The total resistance rate to Pto in 229 strains was 8.7% (20/229), which was 8.4% (12/143) and 9.3% (8/86) in MDR-TB and pre-XDR-TB, respectively. Among the inhA mutant strains, 13 were resistant to the Pto phenotype, and the resistance rate was 65% (13/20). In MDR-TB and pre-XDR-TB strains resistant to Pto, inhA gene mutations occurred in 66.7% (6/9) and 63.6% (7/11), respectively. The resistance rates of MDR-MTB and pre-XDR-TB strains without inhA gene mutation to Pto were 2.4% (3/125) and 5.7% (4/70), respectively.

Characteristics of Mycobacterium tuberculosis serine protease Rv1043c in enzymology and pathogenicity in mice

The serine proteases of Mycobacteria tuberculosis(Mtb)are important contributors to the process of bacterial invasion and its pathogenesis.In the present study,we systematically characterized the role of the Rv1043c protein in Mycobacterium infection by purifying the Rv1043c protein in Escherichia coli and constructing a Mycobacterium smegmatis(Msg)strain overexpressing Rv1043c(Msg_Rv1043c).We found that Rv1043c had serine protease activity and localized to the surface of Mtb.We determined that the optimal pH and temperature for the Rv1043c serine protease were 9.0 and 45°C,respectively.Moreover,the serine protease activity of Rv1043c was enhanced by divalent metal ions of Ca^(2+)and Mg^(2+).Site-directed mutagenesis studies demonstrated that the serine 279 residue in Rv1043c plays a catalytic role.Additionally,mouse model studies confirmed that Rv1043c significantly enhanced the survival of Msg in vivo,induced pulmonary injury and lung cell apoptosis,and promoted the release of pro-inflammatory cytokines interleukin-1βand interleukin-6 in mice.This study presents novel insights into the relationship between mycobacterial serine protease and the pathogenesis of the disease.

Evaluation of Microsphere-based xMAP Test for gyrA Mutation Identification in Mycobacterium Tuberculosis

Drug-resistant(DR) tuberculosis(TB) is a growing threat to public health[1]. Fluoroquinolone(FQ) antibiotics have long been used as anti-tuberculosis drugs, and their widespread application has led to the development of resistance in clinical isolates of Mycobacterium tuberculosis complex(MTBC).

Characterization of Mutations in Genes Related to Rifampicin and Isoniazid Resistance in Multidrug-resistant Mycobacterium tuberculosis Strains from Hangzhou,China

Tuberculosis(TB),caused by the Mycobacterium tuberculosis complex(MTBC),is the 13^(th)leading cause of death and the second leading cause of infectious killer after COVID-19(above HIV and AIDS),according to the World Health Organization's 2022 Global TB Report.In 2021,10.6 million people were diagnosed with a new episode of TB and 1.6 million people died as a result.

Involvement of 2'-5'oligoadenylate synthetase-like proteinin the survivalof Mycobacterium tuberculosis avirulent strain in macrophages

Mycobacterium tuberculosis(M.tuberculosis)can replicate in the macrophage by interfering with many host protein functions.While it is far from known these host proteins for controlling M.tuberculosis infection.Herein,we infected macrophages including THP-1 and Raw264.7 cells with M.tuberculosis and identified the differentially expressed genes(DEGs)in the interferon signaling pathway.Among them,2'-5'oligoadenylate synthetase-like(OASL)underwent the greatest upregulation in M.tuberculosis-infected macrophages.Knockdown of the expression of OASL attenuated M.tuberculosis survival in macrophages.Further,bioinformatics analysis revealed the potential interaction axis of OASL-TAB3-RvO127,which was further validated by the yeast-two-hybrid(Y2H)assay and Co-IP.This interaction axis might regulate the M.tuberculosis survival and proliferation in macrophages.The study reveals a possible role of OASL during M.tuberculosis infection as a target to control its propagation.

Contribution to the Study of Resistance to Anti-Tuberculosis Drugs in the Mycobacterium tuberculosis Complex Isolated at the National Laboratory of Clinical Biology and Public Health in Bangui in the Central African Republic in 2022: Case of Rifampicin

Microscopy-positive and drug-resistant pulmonary tuberculosis (MPT+) is one of the most feared diseases due to the cost of its management and the associated mortality. The GeneXpert, a new molecular test, is in greater demand for the diagnosis of MPT+ resistance cases. The application of GeneXpert to new cases of MPT+ is not effective in the country’s TB screening centres. The objective of this study is to assess the contribution of GeneXpert to the determination of MPT+ resistance cases in Bangui. The study was cross-sectional and covered the period from February to July 2022. The diagnosis of tuberculosis was first performed by microscopy with Ziehl Neelsen hot stain. The GeneXpert was then used to test for resistance in the sputum of all patients with positive microscopy. The collected data was entered into Excel 2013 and analysed with Epi Info 3.3.7. We analysed data from 755 patients, 80 of whom had resistance. The 80 patients ranged in age from 6 to 68 years (mean age = 35 years). The prevalence of resistant TB was 10.60% (80/755). Primary resistance accounted for 73.75% and secondary resistance for 26.25%. The age group 20 - 39 years (57.50%), male (72.50%), 8th district (17.50%), people living in couples (53.75%), farmers (13.75%) were the socio-demographic characteristics most affected by resistance. Treatment failure (13.75%), relapses (13.75%), the notion of contagion (28.75%), a history of smoking (40%) and alcohol (61.25%) were the clinical antecedents reported by the patients. Treatment failure and relapse were the variables associated with the occurrence of resistant PMT+ (p 0.05). A considerable proportion of the overall Mycobacterium tuberculosis resistance to anti-tuberculosis drugs (10.60%) was identified by GeneXpert. Treatment failure and relapse were the factors associated with the risk of resistance.

Characterization of Mycobacterium Species Circulating among Tuberculosis Patients in Bayelsa State, Nigeria

Introduction: Tuberculosis is caused by infection with Mycobacterium tuberculosis. Looking at the evolution of the bacterium gene due to mutation is crucial to identify species circulating among patients in an area. WHO speculated that tuberculosis is caused by M. tuberculosis (MTB), but identification of the strains of MTB circulating in a particular area is important for the management of MTB and to identify pulmonary infections caused by non-tuberculosis mycobacterium. Contact tracing of drug resistant MTB in circulation in an area is also an important procedure of MTB therapeutic choice. Aim: This study aimed to isolate and identify Mycobacterium species circulating in Bayelsa State, Nigeria. Materials and Methods: A total of 102 sputum samples collected from MTB patients were cultured in Lowenstein Jensen (LJ) solid media. Isolates on LJ media were confirmed using Zeihl Nelseen staining method for AFB and Standard Diagnosis Bioline TB Ag MPT64 Rapid test kit. The 16s rRNA gene amplification, agarose gel electrophoresis, and gene sequencing were conducted. Phylogenic analysis and evolutional distances of the strains are computed using the Juke-cantor method. Result: Out of 102 sputum samples examined 15 (14.7%) had growth of Mycobacterium species (AFB positive). The extracted DNA of MTB amplified on agarose gel electrophoresis aligned horizontally at lanes 1 - 15 showing 16S gene band (1500 bp). Two 2 (2.0%) are non-tuberculosis Mycobacteria species, while 13 (12.7%) were M. tuberculosis. The non-tuberculosis Mycobacterium species isolated are Mycobacteriode abscesses and Mycobacterium kansassii strain FDAARGOS 1534. The tuberculosis strains are Mycobacterium tuberculosis MG003 and R2092 but the predominant strain was MG003. The degree of the genetic evolution of the non-MTB Mycobacterium kansassii strain FDAARGOS 1534 was 75.4%. Conclusion: The two major strains of Mycobacterium tuberculosis (MTB) circulating in Bayelsa State are MTB MG003 and MTB R2092;MTB MG003 was predominant. The non-tuberculosis species are Mycobacteriode abscesses and Mycobacterium kansasii.

Mycobacterium tuberculosis infection among children under fifteen years of age:A population-based study in Indonesia

Objective:To assess the prevalence of Mycobacterium(M.)tuberculosis infection and its associated risks in children under fifteen years of age.Methods:Based on secondary data from the 2018 Indonesian Basic Health Survey(RISKESDAS 2018),this cross-sectional study employed M.tuberculosis infection in children as a dependent variable and age level,sex,region,location,family case positive,and smoking as independent variables.Geospatial analysis was applied to show the prevalence of M.tuberculosis infection and multivariate regression was performed to analyze the risk factors of getting the infection among children under 15 years of age.Results:Prevalence ranges of M.tuberculosis infection among children aged 0-14 years,babies(age<12 months),toddlers(age 12-59 months),and children aged between 5 and 14 years were 0.03%to 0.57%,0%to 0.64%,0%to 0.78%,and 0.01%to 0.53%,respectively in Indonesia.A high prevalence of M.tuberculosis infection among children under 15 years of age was found in Papua and other provinces,such as Kalimantan and Java.Contacting with tuberculosis family members was positively associated with M.tuberculosis infection in children as shown by multivariate logistic regression(OR 8.94;95%CI 5.4-14.6,P<0.05).Conclusions:Contacting with family member who has tuberculosis is related with M.tuberculosis infection among children in Indonesia.Therefore,screening the household for contact with tuberculosis patients is a preventive treatment for children.

Prevalence and Clinical Relevance of Schistosoma mansoni Co-Infection with Mycobacterium tuberculosis: A Systematic Literature Review

Tuberculosis disease stands for the second leading cause of death worldwide after COVID-19, most active tuberculosis cases result from the reactivation of latent TB infection through impairment of immune response. Several factors are known to sustain that process.Schistosoma mansoni, a parasite of the helminth genus that possesses switching power from an immune profile type Th1 to Th2 that favors reactivation of latent TB bacteria. The aim of the study was to assess the prevalence of the co-infection between the two endemic infections. Systematic literature was contacted at the University Clinical Research Center at the University of Sciences, Techniques, and Technologies of Bamako in Mali. Original articles were included, and full texts were reviewed to assess the prevalence and better understand the immunological changes that occur during the co-infection. In total, 3530 original articles were retrieved through database search, 53 were included in the qualitative analysis, and data from 10 were included in the meta-analysis. Prevalence of the co-infection ranged from 4% to 34% in the literature. Most of the articles reported that immunity against infection with helminth parasite and more specifically Schistosoma mansoni infection enhances latent TB reactivation through Th1/Th2. In sum, the impact of Schistosoma mansoni co-infection with Mycobacterium tuberculosis is under-investigated. Understanding the role of this endemic tropical parasite as a contributing factor to TB epidemiology and burden could help integrate its elimination as one of the strategies to achieve the END-TB objectives by the year 2035.

Expression,purification and characterization of Mycobacterium tuberculosis RpfE protein

Resuscitation promoting factor E （RpfE） is one of the five Rpf-like proteins in Mycobacterium tuberculos＆ （M. tuberculosis）. These Rpf-like proteins are secretory, which make them candidates for recognition by the host immune system. In this study, the RpfE gene was amplified from M. tuberculosis, cloned into the expression vectors pDE22 and pPRO EXHT, and were expressed in Mycobacterium vaccae （M. vaccae） and Escherichia coli DHSa, respec- tively. Both recombinant RpfE proteins were purified by Ni-Sepharose affinity chromatography, and were given to C57BL/6 mice. The RpfE proteins elicited T cell proliferation, and stimulated the production of gamma interferon （IFN-y）, interleukin-10 （IL-10） and IL-12. Our results indicated that the RpfE protein expressed in M. vaccae could more efficiently stimulate cellular immune response, making it a promising candidate as a subunit vaccine.

Biological functions and diagnostic implications of microRNAs in Mycobacterium tuberculosis infection

MicroRNAs(miRNAs),small non-coding RNAs,play important roles in regulating host defense against pathogenic infections.This review provides information on the role of miRNAs in the antimycobacterial immune response and summarizes their possible diagnostic utility.It was compiled using scientific literature retrieved from such databases as PubMed,Scopus,ScienceDirect,Google Scholar,and PubMed Central.Relevant articles published in the English language until December 2020 were taken into consideration.It has been revealed that specific host miRNAs induced by Mycobacterium tuberculosis can target diverse factors and pathways in immune signaling to ensure longer pathogen survival inside the phagocytes.The potential use of miRNAs in tuberculosis diagnosis or therapeutic strategies has been attracting increasing attention in recent years.However,despite considerable efforts devoted to miRNA profiling,further studies are needed to elucidate the full potential of miRNAs as novel tuberculosis biomarkers or therapeutic targets.

Detecting katG Drug Resistant Genetic Mutation among pneumoconiosis patients complicated with tuberculosis in Mycobacterium tuberculosis L-forms by PCR-SSCP

Objective：To study the relationship between mutation in the katG gene and drug resistance of INH in Mycobacterium tuberculosis L-forms among patients of pneumoconiosis complicated with pulmonary tuberculosis, and to explore the clinical application of PCR-SSCP. Methods： A total of 52 clinical isolated strains of Mycobacterium tuberculosis L-forms were collected. Mutation in the katG genes was detected by PCR-SSCP and traditional antimicrobial susceptibility test （AST）. Results： The results by AST showed that there were 40 persisters in 52 clinical isolated strains. The drug resistant rate was 76.92%（40/52）, and the gene mutation rate of katG was 57.70%（30/52）by PCR-SSCP, the difference was no quite significance （X^2 = 2.8507, P 〉 0.05）. The coincidence rate of two methods was 75.00% （30/40）. Conclusion： The detectionrate of katG resistant strains in Mycobacterium tuberculosis L-forms was high by PCR-SSCP. The combined application of PCR-SSCP and traditional antimicrobial susceptibility test can improve the detecting rate.

Detecting drug resistant genetic mutation among pneumoconiosis patients complicated with tuberculosis in Mycobacterium tuberculosis L-forms application of PCR-SSCP technique in Huainan mining district

Objective： To study the relationship between drug resistant genetic mutation and drug resistance in Mycobacterium tuberculosis L-form, discuss the internal relationship between drug resistances and drug-resistant related genes and explore the value of PCR- SSCP to clinical application. Methods： A total of 52 clinically isolated strains of tuberculosis L-form were collected among 97 pneumoconiosis patients complicated with tuberculosis. The gene mutations of katG, rpoB and rpsL were detected by PCR-SSCP, and the results were compared with those analyzed by traditional antimicrobial susceptibility test（AST）. Results： The gene muta- tion rates of katG, rpoB and rpsL by PCR-SSCP were respectively 57.70% （30/52）, 65.38% （32/52） and 40.38% （21/52）. The rate of reversion was 78.85%（41/52） and the result of drag-resistant genes was invariable. The results of AST showed that there were 40 （76.92%） multi-drug resistant strains in 52 clinically isolated strains. The number for three-drug resistant strain was 21 （40.38%） and that of two-drug resistant was 19（36.54%）, but only 12（23.08%） strains were one drug resistant. The rate of total drug-resistance was 100%, but there were 15 strains of allied mutation of three genes, 16 of two mutations and 6 of only one by PCR-SSCP. The coincidences were respectively 71.43%, 84.12% and 50.00%. Then there was no significant difference between the allied mutations of multi-drug resistant gene and the mutations of only one drug resistant gene （P 〉 0.05）. Conclusion： PCR-SSCP technique has a higher sensibility and specificity to detect the genes of katG, rpoB and rpsL in tuberculosis L-form among pneumoconiosis complicated with tuberculosis,and the detecting rate of two drug resistant strains and three drug resistant strains was higher. The combined application of PCR-SSCP and AST has advantages at earlier diagnosis and guidance of clinical medications.