Rifampicin Resistance Rate Research Articles

Rifampicin resistance in pulmonary and extra pulmonary tuberculosis cases in of children

: The prevalence of Rifampicin-resistant MTB/EPTB in children in India is a growing concern. Globally a large proportion of childhood tuberculosis (TB) cases are diagnosed based only on clinical findings. This study was undertaken to measure MTB positivity and their rifampicin resistance rates in different clinical samples from children. : Different samples of clinically suspected tuberculosis in children were included. All the samples were tested for Tuberculosis positivity and Rifampicin (Rif) resistance by GeneXpert assay. A total of 1420 samples were received from presumptive TB patients of all age group from February 2023 to January 2024. Total 1420 samples were analyzed for this study, of which 30% were male and 70% were females. Respiratory samples and extra-pulmonary samples were 1261 (88.8%) and 159 (11.2%) respectively. Among 1420, 211(14.86%) samples were from children and among these 75 (35.55%) were found MTB positive and 7 (9.33%) were Rif resistant MTB. Of 75 MTB detected patients, 77.8% and 22.2% MTB detected in female and male children respectively. There are higher prevalence of Rif resistant MTB in children so it is important for healthcare providers in India to be vigilant in timely diagnosis, individualized treatment and enhance surveillance. It is essential to combat this growing threat and protect the health of children.

Tuberculosis prevalence and rifampicin resistance among presumptive patients in Nasarawa State: A three-year retrospective study

Objective: To investigate the prevalence and rifampicin resistance of tuberculosis among presumptive patients in Nasarawa state, Nigeria. Methods: Patient data collected from January 2019 to December 2021 were retrospectively computed from the register at the tuberculosis laboratory of Dalhatu Araf Specialist Hospital, Lafia. A total of 91884 patient records were analyzed to determine tuberculosis prevalence, rifampicin resistance, and patients’ characteristics using Chi-squared test. Results: An overall prevalence of 8.0% was recorded among presumptive patients over the three-year period with a decreasing trend in prevalence from 10.0% (2019) to 6.5% (2021), though the number of samples progressively increased each year and more than doubled in 2021. Most of the patients tested for tuberculosis were females (52.6%) and were mostly older than 15 years (84.1%). Conversely, a higher resistance to rifampicin was observed among tuberculosis positive male patients (55.6%) than in females (44.4%). Similarly, tuberculosis positive patients older than 15 years (84.6%) showed greater resistance to rifampicin than those younger than 15 years (15.4%). Statistically, no relationship was established among age, sex, year of sampling and tuberculosis prevalence or rifampicin resistance rate. Conclusions: Despite the downward trends in tuberculosis prevalence and rifampicin resistance rate observed in this study, measures at maintaining the gains achieved in the fight against tuberculosis must remain paramount as the race towards reducing tuberculosis incidence and mortality by 2025 continues.

Burden of rifampicin resistance in methicillin-resistantStaphylococcus aureusamong apparently healthy students at the University of Jos, Jos, Nigeria

ObjectivesAs a broad-spectrum antibiotic, rifampicin is used to treat staphylococcal infections. Due to its chemical makeup, it can easily get into tissues and abscesses, which majority of the other antibiotics (anti-staphylococcal drugs) have trouble doing. To treat these infections, methicillin-resistantStaphylococcus aureus(MRSA) isolates exhibit rapid evolution of rifampicin resistance, necessitating use of costly medicines. This study, therefore, assessed the burden of rifampicin resistance rate among MRSA in Jos, Nigeria.Material and MethodsA total of 92 samples were collected from students at the University of Jos.S. aureuswas isolated and identified by conventional methods. Susceptibility test was conducted to determine MRSA. After that, the MRSA was challenged with 30 µg of rifampicin using the Kirby–Bauer disk diffusion method.ResultsOut of the 92 samples that were isolated, 45 (48.91%) were from female students, while 47 (51.09%) were from male students. 57 (61.96%) samples were positive forS. aureus. Of the 57 (61.96%)S. aureusisolates recovered, 32 (56.14%) were found to be MRSA. These were subjected to rifampicin, and 18 (56.25%) showed resistance. The susceptibility patterns ofS. aureusagainst antibiotics tested showed a susceptibility of 94.74, 77.19, 75.44, 73.68, 71.93, 64.91, 52.63, 43.86, and 31.58% to ofloxacin, clindamycin, chloramphenicol, ciprofloxacin, gentamycin, erythromycin, trimethoprim/sulfamethoxazole, cefoxitin, and tetracycline, respectively.ConclusionIt was concluded that MRSA were present in the study population, and a substantial number (56.25%) of these were rifampicin resistant.

Tuberculosis positivity in different clinical samples and their rifampicin resistance status detected by Truenat MTB/RIF assay in a tertiary care hospital

Background: Tuberculosis (TB) causes 1.8 million deaths per year globally. TB is now a global priority for research and development. India accounts for >1/4th of global TB burden - 27 lakh out of 1 Crore new cases annually. Many patients with extrapulmonary TB (EPTB) can have pulmonary involvement who can be potentially infectious. Aims and Objectives: This study was undertaken to measure TB positivity and their rifampicin resistance rates in different clinical samples. Sputum TB positivity in EPTB patients was also detected. Materials and Methods: Different samples of clinically suspected patients accounting for 1427 patients for 3 months were tested for TB positivity and Rifampicin resistance by Truenat MTB/RIF assay in R. G. Kar MCH. Biopsy, bones, and tissues were excluded due to lack of facility. Their demographic profile and risk factors were recorded. Results: TB positivity and rifampicin resistance rates in positive samples respectively – sputum (19.01%, 7.86%), pleural fluid (10.78%, 9.11%), bronchoalveolar lavage fluid (4%, 0%), DTA (0%, 0%), gastric lavage (5.26%, 0%), L.N. fine needle aspiration cytology (6.25%, 0%), ascitic fluid (2.13%, 0%), cerebrospinal fluid (5.17%, 0%), urine (2.13%, 0%), and synovial fluid (50%, 0%). Rifampicin resistance was more common among pulmonary samples. Patients with pleural TB had the highest associated sputum TB positivity. Important risk factors were smoking, diabetes, HIV infection, and post-COVID. Overall, the most common age group affected: 21–40 years (38%) including males (64.8%) and females (35.2%). Conclusion: Truenat, sensitive and specific testing with low turnaround time in resource-poor settings is excellent for early diagnosis and prompt treatment of both pulmonary and EPTB. Overall, pulmonary TB had greater rifampicin resistance rates. Smoking, diabetes, HIV infection, and post-COVID infection were associated risk factors.

Trends of Rifampicin Resistance in Patients with Pulmonary Tuberculosis: A Longitudinal Analysis Based on Drug Resistance Screening in Eastern China Between 2015 and 2019.

To understand the trend of overall rifampicin resistance rates for tuberculosis in Zhejiang Province between 2015 and 2019. The basic demographic information of patients with tuberculosis who were screened for drug resistance in Zhejiang Province between January 1, 2015 and December 31, 2019 was collected through the national Tuberculosis Information Management System. The data were processed and analyzed using IBM SPSS 26.0 and GeoDa 1.14 software. The total rifampicin resistance rate was 5.9% in 53,893 validated cases of drug resistance screening conducted in patients with pulmonary tuberculosis in Zhejiang Province during the study period. There was a decreasing trend in the rifampicin resistance rate in both initial and re-treated patients (P<0.001), but the rifampicin resistance rate was higher in re-treated TB patients than in TB patients receiving their initial treatment (11.4% vs 4.2%). The rate of drug resistance steadily decreased in all prefectures, and there was a significant upward trend in the use of the Xpert MTB/RIF rapid assay. An increasing trend was also identified in the rate of rifampicin and ofloxacin co-resistance (P<0.001). The overall rate of rifampin resistance in patients with tuberculosis in Zhejiang Province in the past five years has shown a decreasing trend, but the rate of resistance to ofloxacin was high. Resistance testing to fluoroquinolones should be carried out as early as possible in patients whose diagnosis results indicate rifampin resistance, and more effective second-line treatment plans should be developed based on the results of this testing.

Detection of Helicobacter pylori by invasive tests in adult dyspeptic patients and antibacterial resistance to six antibiotics, including rifampicin in Turkey. Is clarithromycin resistance rate decreasing?

Background/aimThe prevalence of Helicobacter pylori is reported to be roughly 80% in Turkey, and only very few culture-based studies are available on antibacterial resistance in adult dyspeptic patients. This study was carried out in adult dyspeptic patients with an aim to: (i) detect H. pylori by invasive tests (culture, polymerase chain reaction, and histopathology) and (ii) determine the current resistance rates of H. pylori isolates to six antibiotics, including rifampicin.Materials and methodsThis study was conducted in 422 adult dyspeptic patients. The presence of H. pylori was demonstrated by culture, polymerase chain reaction, and the histopathology of gastric biopsy material. Antibacterial susceptibility was determined with the E-test.ResultsThe mean age of the patients was 50 ± 15 (range 18–90), and 265 (63%) of them were female. By culture, polymerase chain reaction, and histopathology, the presence of H. pylori was detected at rates of 35% (148/422), 67% (281/422), and 53% (224/422), respectively. The prevalence of H. pylori was determined as 75.6% (319/422). Metronidazole, levofloxacin, clarithromycin, and rifampicin resistance rates were 62%, 36%, 19%, and 12%, respectively. Monodrug, dual-drug, and multidrug resistance rates were ascertained as 36.9%, 29.4%, and 10.5%, respectively. All of the isolates were susceptible to amoxicillin and tetracycline.ConclusionThis study revealed the current prevalence of H. pylori in adult dyspeptic patients as 75.6%, and thereby, showed that infection with this pathogen remains highly prevalent. Although resistance to metronidazole and levofloxacin has increased over time, clarithromycin resistance rate has decreased. The high levels of resistance to metronidazole and levofloxacin limit the empirical use of these antibiotics in the eradication protocol. Owing to the low level of resistance determined for rifampicin, this antibiotic could be included in the eradication protocol, in the event of the need for rescue therapy in Turkey.

Discordance of the Repeat GeneXpert MTB/RIF Test for Rifampicin Resistance Detection Among Patients Initiating MDR-TB Treatment in Uganda.

BackgroundThe Global Laboratory Initiative (GLI) guidelines recommend repeat for GeneXpertMTB/RIF (XpertMTB/RIF) in patients with a low pretest probability of rifampicin resistance (RR).MethodsThis was a cross-sectional study using results of sputum specimens collected from participants screened for the STREAM 2 trial. We recruited all patients with XpertMTB/RIF RR-TB detected who were referred for RR/multidrug-resistant (MDR) TB treatment initiation at Mulago National Referral Hospital, Kampala, between September 2017 and October 2019. At baseline, smear microscopy, repeat XpertMTB/RIF, Xpert Ultra, and MTBDRplus assays were done on sputum specimens. Culture-based drug susceptibility testing (DST) was performed on discordant specimens. We analyzed the prevalence and factors associated with discordance between initial and repeat XpertMTB/RIF RR and false XpertMTB/RIF RR. False XpertMTB/RIF RR was defined as no RR detected by any of Xpert Ultra, LPA, or culture DST (reference comparator).ResultsA total of 126/130 patients had repeat XpertMTB/RIF results, of whom 97 (77.0%) had M. tuberculosis detected, 81 (83.5%) had RR detected, and 1 (1.0%) had RR indeterminate. The prevalence of discordant XpertMTB/RIF RR was 15/96 (15.6%), whereas false XpertMTB/RIF RR prevalence was 10/96 (10.4%).Low–bacillary load sputum specimens were more likely to have discordant XpertMTB/RIF RR and false XpertMTB/RIF RR results (adjusted odds ratio [aOR], 0.04; 95% CI, 0.00–0.37; P = .01; aOR, 0.02; 95% CI, 0.01–0.35; P = .01, respectively).ConclusionsOur findings show a high false-positive rifampicin resistance rate in low–TB burden patients, which calls for repeat testing in order to prevent unnecessary prescription of anti-MDR-TB therapy.

Utility of CBNAAT in diagnosis of mycobacterium tuberculosis in a tertiary care teaching hospital in South India

Background: Tuberculosis is the ninth leading cause of death worldwide. India contributes to about one fifth of global TB burden. It is very important to diagnose early and treat Tuberculosis to cut down transmission of Tuberculosis. Material and Methods: We conducted a retrospective study in department of Pulmonary medicine to analyze the utility and yield of CBNAAT from Jan- Dec 2017. We included all patients who were subjected to CBNAAT in the study period. Data was collected from ART centre, DOTS centre and CBNAAT centre. We collected total number of samples tested for CBNAAT, indication for CBNAAT, HIV status, result of smear microscopy for AFB and CBNAAT. Results: A total of 1703 samples were tested in CBNAAT during the study period. Mean age of the study population was 35.5±10.2 years. 1366 tested were negative and 290 samples were positive for CBNAAT. Of these 290 positive samples, 267 were sputum/BAL samples and 23 were extra pulmonary samples. We found rifampicin resistance rate of 2.4% (8/329) in pulmonary tuberculosis cases, There were no rifampicin resistance detected in extra pulmonary samples. CBNAAT could identify 184 cases (13.3%) that were smear negative. We found TB- HIV coinfection rate of 10.02%. Conclusions: We found CBNAAT to be an important diagnostic modality especially in sputum negative patients for early diagnosis and treatment. We could detect Mycobacterium tuberculosis in 13.4% of patients with negative smear for microscopy. In PLHIV, CBNAAT detected Mycobacterium Tuberculosis in 9.3% of patients. We found rifampicin resistance rate of 2.4% (8/329) in pulmonary tuberculosis cases. Keywords: CBNAAT; Tuberculosis; Smear negative; PLHIV.

Prevalence of Mycobacterium tuberculosis and Its Rifampicin Resistance among Patients Attending General Hospital Mararaba as a Case Study

Aims: To determine the prevalence of Mycobacterium tuberculosis and its Rifampicin resistance among patients attending General Hospital, Mararaba.&#x0D; Study Design: This was a descriptive health-based research that involved clinically suspected tuberculosis patients whose sputum samples were referred to General Hospital Mararaba for diagnosis.&#x0D; Place and Duration of Study: Department of tuberculosis, General Hospital Mararaba Nasarawa state between May to July 2019.&#x0D; Methodology: A total of 100 suspected TB patients of both male and female were included in the study. Two sputum samples from each patient were collected from these patients with sputum containers and samples were processed under level 3 biosafety cabinet by mixing with the reagent that was provided with the assay following manufacturer’s manual and thereafter, the cartridge containing this mixture was placed in the Gene Xpert machine. The processing of the sample is fully automated and takes less than two hours.&#x0D; Results: An overall prevalence of 21.5% was recorded for Mycobacterium tuberculosis with a rifampicin resistance rate of 65.11% among positive patients. The highest prevalence of infection was observed among the age group of above 40 years (40.0%), males (23.9%), self-employed people (25.6%), those living in a rural environment (31.8%) and those with informal education (35.7%). There was no statistically significant relationship between the prevalence of MTB to sex, marital status, education, employment and ethnicity (P&gt;0.05). Environment factor was however significant (p&lt;0.05). Highest frequency for rifampicin resistance was recorded in the age group 20-29(39.2%), (64.28%) in males, rural areas (57.14%), self-employed persons (57.14%) and single people (50.0%). Age about rifampicin resistance was significant (p&lt;0.05) while sex, occupation, environment and rural areas were not significant (p&gt;0.05).&#x0D; Conclusion: It was concluded that Mycobacterium tuberculosis and its Rif-resistance amongst patients attending General Hospital, Mararaba is comparatively high and indicative of the rate at which tuberculosis and drug resistance is still resilient despite various methods put in place to control it.

Rifampicin resistance among patients with Tuberculosis at the Olabisi Onabanjo University Teaching Hospital, Sagamu

Background: Tuberculosis (TB) is a major public health problem in Nigeria. The emergence of multidrug-resistant Tuberculosis poses a threat to global Tuberculosis control and if not effectively addressed, may wipe out the achievements of previous efforts in controlling Tuberculosis. Objectives: To determine the prevalence and factors associated with rifampicin resistance amongpatients receiving care for TB at the OlabisiOnabanjo University Teaching Hospital, Sagamu. Methods: A retrospective study of presumptive Tuberculosis cases managed between January 2013 and December 2016 at the Directly Observed Treatment clinic, OlabisiOnabanjoUniversity Teaching Hospital Sagamu, Ogun State, Nigeria,was done. One sputum sample was obtained from each patient for the Gene Xpert® test to diagnoseTB and to determine rifampicin resistance among patients with confirmed Mycobacterium tuberculosis infection. HIV screening was also carried out on all the patients using HIV Rapid Test kits. The sociodemographic data were retrieved from the presumptive Tuberculosis register. Results: A total of 1572 presumptive TB patients were screened for TB, out of which 187 (11.8%) were confirmed to be infected with Mycobacterium tuberculosis (MTB). A total of 20 (10.7%) of the 187 MTB patients had rifampicin resistance using Gene Xpert® method. Rifampicin resistance rate was significantlyassociated with re-treatment TB category but not with age, sex or HIV status. Conclusion: The study showed rifampicin drug resistance among confirmed TB patients. There is a need to decentralizethe use of Gene Xpert® test for TB to the peripheral facilities and make it a point of care test for presumptive TB patients.

Surveillance of Antibiotic Resistance among Hospital- and Community-Acquired Toxigenic Clostridium difficile Isolates over 5-Year Period in Kuwait.

Clostridium difficile infection (CDI) is a leading and an important cause of diarrhea in a healthcare setting especially in industrialized countries. Community-associated CDI appears to add to the burden on healthcare setting problems. The aim of the study was to investigate the antimicrobial resistance of healthcare-associated and community-acquired C. difficile infection over 5 years (2008–2012) in Kuwait. A total of 111 hospital-acquired (HA-CD) and 35 community-acquired Clostridium difficile (CA-CD) clinical isolates from stool of patients with diarrhoea were studied. Antimicrobial susceptibility testing of 15 antimicrobial agents against these pathogens was performed using E test method. There was no evidence of resistance to amoxicillin-clavulanic acid, daptomycin, linezolid, piperacillin-tazobactam, teicoplanin and vancomycin by both HA-CD and CA-CD isolates. Metronidazole had excellent activity against CA-CD but there was a 2.9% resistance rate against HA-CD isolates. Ampicillin, clindamycin, levofloxacin and imipenem resistance rates among the HC-CD vs. CA-CD isolates were 100 vs. 47.4%; 43 vs. 47.4%; 100 vs. 100% and 100 vs. 89%, respectively. An unexpected high rifampicin resistance rate of 15.7% emerged amongst the HA-CD isolates. In conclusion, vancomycin resistance amongst the HA-CD and CA-CD isolates was not encountered in this series but few metronidazole resistant hospital isolates were isolated. High resistance rates of ampicillin, clindamycin, levofloxacin, and imipenem resistance were evident among both CA-CD and HA-CD isolates. Rifampicin resistance is emerging among the HA-CD isolates.

Effects of Introducing Xpert MTB/RIF on Diagnosis and Treatment of Drug-Resistant Tuberculosis Patients in Indonesia: A Pre-Post Intervention Study.

BackgroundIn March 2012, the Xpert MTB/RIF assay (Xpert) was introduced in three provincial public hospitals in Indonesia as a novel diagnostic to detect tuberculosis and rifampicin resistance among high risk individuals.ObjectiveThis study assessed the effects of using Xpert in place of conventional solid and liquid culture and drug-susceptibility testing on case detection rates, treatment initiation rates, and health system delays among drug-resistant tuberculosis (TB) patients.MethodsCohort data on registration, test results and treatment initiation were collected from routine presumptive patient registers one year before and one year after Xpert was introduced. Proportions of case detection and treatment initiation were compared using the Pearson Chi square test and median time delays using the Mood’s Median test.ResultsA total of 975 individuals at risk of drug-resistant TB were registered in the pre-intervention year and 1,442 in the post-intervention year. After Xpert introduction, TB positivity rate increased by 15%, while rifampicin resistance rate reduced by 23% among TB positive cases and by 9% among all tested. Second-line TB treatment initiation rate among rifampicin resistant patients increased by 19%. Time from client registration to diagnosis was reduced by 74 days to a median of a single day (IQR 0–4) and time from diagnosis to treatment start was reduced by 27 days to a median of 15 days (IQR 7–51). All findings were significant with p<0.001.ConclusionCompared to solid and liquid culture and drug-susceptibility testing, Xpert detected more TB and less rifampicin resistance, increased second-line treatment initiation rates and shortened time to diagnosis and treatment. This test holds promise to improve rapid case finding and management of drug-resistant TB patients in Indonesia.

Tuberculosis and rifampicin resistance among migrants in kyrgyzstan: detection by a new diagnostic test.

This cross-sectional study aimed to describe suspected tuberculosis (TB) cases among migrants in Kyrgyzstan and to estimate the accuracy of Xpert MTB/RIF, which has been operated in Kyrgyzstan since 2012. Characteristics of 3,714 suspected cases among migrants were analysed. In addition, by using data of 300 cases with culture results, sensitivity and specificity of Xpert MTB/RIF, both for detection of TB and rifampicin susceptibility, were assessed. Among 3,714 suspected cases, 56.1% were male, and the median age was 35 years old. Of the suspected cases, 17.2% were previously-treated. In total, 809 (21.8%) were smear-positive; 36.8% among previously-treated cases and 18.7% among new cases. Among 300 selected participants, 235 (78.3%) were culture-positive. Of those who were confirmed as TB positive, recurrent cases showed a higher proportion of rifampicin resistance than new cases (59.3% vs 42.6%). For detection of TB, the sensitivity and specificity of XpertMTB/RIF (81.3% and 98.2%) were higher than those of microscopy (70.2% and 71.4%). Sensitivity and specificity for detection of rifampicin resistance were 96.8% and 91.8%, respectively. The rifampicin resistance rate in the study population was higher than the national average. Xpert MTB/RIF showed higher accuracy in detecting TB cases than microscopic diagnosis. Higher accuracy and earlier detection of drug susceptibility is especially important for those who have difficulty in accessing healthcare and those who are easily lost from tracking, including migrants.

Genetic basis of rifampicin resistance in methicillin-resistant Staphylococcus aureus suggests clonal expansion in hospitals in Cape Town, South Africa

BackgroundSince 2001, several studies have reported high rifampicin resistance rates (45 - 100%) among methicillin-resistant Staphylococcus aureus (MRSA) isolates from South Africa. The authors previously characterised 100 MRSA isolates from hospitals in Cape Town, South Africa; forty-five percent of these isolates were rifampicin-resistant. The majority (44/45) corresponded to ST612-MRSA-IV, which is prevalent in South Africa, but has not been reported frequently elsewhere. The remaining rifampicin-resistant isolate corresponded to ST5-MRSA-I. The aim of this study was to investigate further the prevalence and genetic basis of rifampicin-resistance in MRSA isolates from hospitals in Cape Town.ResultsBetween July 2007 and June 2011, the prevalence of rifampicin-resistant MRSA in hospitals in Cape Town ranged from 39.7% to 46.4%. Based on the results of the aforementioned study, nine ST612-MRSA-IV isolates, the rifampicin-resistant ST5-MRSA-I isolate, and two rifampicin-susceptible MRSA isolates were investigated. Four previously described ST612-MRSA-IV isolates, including two each from South Africa and Australia, were also included.The ST5-MRSA-I isolate carried a single mutational change, H481Y, commonly associated with high-level rifampicin resistance. All ST612-MRSA-IV isolates carried an uncommon double amino acid substitution in RpoB, H481N, I527M, whilst one of the Australian ST612-MRSA-IV isolates carried an additional mutation within rpoB, representing a novel rpoB genotype: H481N, I527M, K579R. All ST612-MRSA-IV isolates also shared a unique silent single nucleotide polymorphism (SNP) within rpoB.ConclusionsThat local ST612-MRSA-IV isolates described here share an uncommon rpoB genotype and a unique silent SNP suggests this clone may have undergone clonal expansion in hospitals in Cape Town. Further, the data suggest that these isolates may be related to rifampicin-resistant ST612-MRSA-IV previously described in South Africa and Australia.

Increased rifampicin resistance in blood isolates of meticillin-resistant Staphylococcus aureus (MRSA) amongst patients exposed to rifampicin-containing antituberculous treatment

The aim of this study was to determine the rifampicin (RIF) resistance rate of meticillin-resistant Staphylococcus aureus (MRSA) amongst patients with MRSA bacteraemia who have or have not been exposed to RIF-containing antituberculous (anti-TB) treatment. From 2000 to 2008, patients with MRSA bacteraemia and previous exposure to RIF-containing anti-TB therapy were selected. Patients matched for sex, age and time of culture of MRSA bacteraemia but without exposure to anti-TB therapy were selected as a control group. A total of 139 patients, comprising 49 with RIF exposure and 90 without RIF exposure, were analysed. The RIF resistance rate was higher in patients with previous RIF exposure (61.2% vs. 20.0%; P < 0.001). The minimum inhibitory concentration of RIF that inhibited 50% of MRSA isolates (MIC 50) for the study group was also higher (128 mg/L vs. 0.015 mg/L; P < 0.001). The mortality rate was higher in the study group (59.2% vs. 41.1%; P = 0.041). MRSA isolates recovered from patients with current usage of a RIF-containing anti-TB regimen were more likely to be resistant to RIF (87.5% vs. 36%; P = 0.001), with higher MIC 50 values (256 mg/L vs. 1 mg/L; P = 0.002), and resulted in a higher mortality rate than isolates from patients with remote usage of an anti-TB regimen (79.2% vs. 40%; P = 0.005). Multivariate analysis showed that current anti-TB drug usage was the only risk factor for RIF resistance [odds ratio (OR) = 7.457, 95% confidence interval (CI) 1.581–35.167] and mortality (OR = 7.201, 95% CI 1.583–32.766). Given the high rate of RIF resistance in patients with prior anti-TB treatment, RIF susceptibility testing should be performed before considering combination treatment of RIF in MRSA infection.

A Trend in Acquired Drug Resistances of Tuberculosis Patients Registered in Health Centers from 1981 to 2004

Background : The drug resistance rate in tuberculosis patients with history of chemotherapy is an important indicator of for evaluation of appropriateness of treatment regimens and compliance of patients. This study examined the long-term changes in the drug resistance rates among TB patients failed in treatment or reactivated. Methods : The results of drug susceptibility testing data from patients registered in health centers from 1981 to 2004 were analyzed. Results : The rate of resistance to isoniazid decreased from 90% to 20%, and the resistance to ethambutol decreased from 45% to 6%. The rate of resistance to rifampicin varied from 13% to 28% and the resistance to pyrazinamide was 5% to 10%. Multidrug resistance was about 2-3% lower than any rifampicin resistance rates. The second-line drug resistance was ranged from 1% to 3%. There was no difference between patients' genders. Patient numbers per 100,000 population increased with age. The regional distribution was even at 4-6 patients per 100,000 population, and drug resistance rates were significantly lower in big city areas than in small towns and rural areas. Conclusion : The rates of resistance of Mycobacterium tuberculosis isolated from TB patients with history of chemotherapy to isoniazid, rifampin, ethambutol, and isoniazid plus rifampin were significantly decreased during over two decades.