Surveillance of Mycobacterium tuberculosis drug resistance in France, 1995-1997. AZAY Mycobacteria Study Group.

OBJECTIVE: To measure the rate of primary and secondary drug resistance of Mycobacterium tuberculosis on an ongoing basis. DESIGN: Data on all culture-positive tuberculosis were collected prospectively from 1995 through 1997 from a microbiological laboratory network of 19 university hospitals throughout France, and submitted quarterly to the National Reference Centre for Surveillance of Mycobacterial Diseases. RESULTS: A total of 2998 patients were included in the study. Among the 2333 (78%) previously untreated patients, 8.6% had isolates resistant to any drug, 4.8% to streptomycin (SM) alone, 1.2% to isoniazid (INH) alone, 1.8% to SM + INH, and 0.3% to INH + rifampicin (RMP) or multidrug resistance (MDR). Foreign birth was independently associated with a higher risk of primary resistance to any drug (odds ratio [OR] 1.5). Among the 268 (9%) previously treated patients, 20.9% had isolates resistant to any drug, 6.3% to SM alone, 3.4% to INH alone, 4.1% to SM + INH, and 3.7% to INH + RMP. Foreign birth (OR = 2.3), and human immunodeficiency virus positive status (OR = 4.4) were independently associated with a higher risk of secondary resistance to any drug. CONCLUSION: During the last 30 years there has been no increase in resistance to any drug among previously untreated patients. As expected, secondary resistance was highly associated with foreign birth. MDR-TB remains a rare event in France.     

High prevalence of drug-resistant tuberculosis, Republic of Lithuania, 2002.

BACKGROUND: Nations of the former Soviet Union have the world's highest reported levels of resistance to anti-tuberculosis drugs. We conducted the first national survey of anti-tuberculosis drug resistance in the Republic of Lithuania. METHODS: We tested Mycobacterium tuberculosis isolates from all incident culture-positive pulmonary TB patients registered in 2002. New patients were those treated for <1 month with any first-line anti-tuberculosis drug (isoniazid [INH], rifampin [RMP], ethambutol, or streptomycin); previously treated patients were those treated for > or =1 month. RESULTS: Of 1163 isolates, 475 (41%) were resistant to at least one first-line drug, and 263 (23%) were resistant to at least INH and RMP (MDR); this included 76/818 (9.3%) from new patients and 187/345 (54%) from previously treated patients. Of 52 MDR isolates randomly selected for extended testing at an international reference laboratory, 27 (51%, 95%CI 38-66) had resistance to pyrazinamide, 21 (40%, 95%CI 27-55) to kanamycin, and 9 (17%, 95%CI 8-30) to ofloxacin. CONCLUSIONS: The prevalence of MDR-TB in Lithuania is among the world's highest. Among MDR-TB isolates, aminoglycoside and fluoroquinolone resistance were common. To combat drug-resistant TB, Lithuania has implemented the WHO global TB control strategy (DOTS), and is developing an MDR-TB treatment program (DOTS-Plus).     

Isoniazid- and rifampin-resistant tuberculosis in San Diego County, California, United States, 1993-2002.

SETTING: A local tuberculosis (TB) control program. OBJECTIVES: To measure trends in isoniazid (INH) and rifampin (RMP) resistance and identify associated factors. DESIGN: Retrospective review. RESULTS: Of 2883 isolates obtained from TB patients reported between 1993 and 2002, 287 (10%) were resistant to INH, 11 (< 1%) were resistant to RMP, and 40 (1%) were resistant to both (multidrug resistance [MDR]). There were no linear trends over time. Eighty-one per cent of patients with INH resistance and 85% with MDR were born outside the United States. Sixty-three per cent of patients with drug resistance and prior TB treatment were treated outside the US. INH resistance was associated with race/ethnicity and prior treatment, RMP resistance with human immunodeficiency virus (HIV) infection, and MDR with non-US birth and prior treatment. Patients with INH- and RMP-susceptible or INH-resistant TB had higher percentages of treatment completion and sputum culture conversion than patients with RMP-resistant or MDR-TB. CONCLUSIONS: INH and RMP resistance remained stable between 1993 and 2002. Because most patients with drug resistance were infected or initially treated outside the US, future reductions in drug resistance will depend not only on local and national efforts, but also on the success of global interventions.     

Evaluation of drug resistance in pulmonary tuberculosis patients at Sureyyapasa Chest Diseases Hospital, Istanbul, Turkey.

SETTING: Sureyyapasa Chest Diseases and Thoracic Surgery Training Hospital, Istanbul, Turkey. OBJECTIVE: To determine levels of Mycobacterium tuberculosis resistance to first-line drugs in patients with pulmonary tuberculosis (PTB). DESIGN: Between 1 January and 31 December 2005, all hospitalised PTB patients with culture-positive M. tuberculosis specimens and corresponding drug susceptibility tests (DST) for isoniazid (INH), rifampicin (RMP), streptomycin (SM) and ethambutol, routinely performed for every tuberculosis (TB) case at our centre, were included. RESULTS: Of a total of 1513 cases, 1277 (84.4%) were new and 236 (15.6%) were previously treated cases. Of the 1513 isolates, 290 (19%) isolates were resistant to at least one of the drugs tested. Resistance among new and previously treated cases was respectively 16.3% (209 of 1277) and 34.3% (81/236). Any SM resistance and any INH resistance were the most common drug resistance in new cases, while any RMP resistance was the most common drug resistance in previously treated cases. Multidrug resistance was detected in 3.2% (n = 41) of new cases and in 13.5% (n = 32) of previously treated cases. CONCLUSION: Planning for TB control requires an assessment of the number and distribution of drug-resistant cases, with laboratories providing accurate and reliable results.     

Rifampicin mono-resistant Mycobacterium tuberculosis in Bujumbura, Burundi: results of a drug resistance survey.

SETTING: Bujumbura, Burundi. OBJECTIVES: To determine resistance levels of Mycobacterium tuberculosis (TB) to the main anti-tuberculosis drugs after 11 years of a DOTS programme using a WHO-recommended partially intermittent 6-month rifampicin (RMP) first-line regimen and fixed-dose drug combinations (FDCs). DESIGN: Drug susceptibility testing of systematic samples of M. tuberculosis isolated from newly registered sputum smear-positive cases in the capital during a 15-month period (2002-2003). RESULTS: Of 496 strains from new cases, 16.1% showed resistance to any drug, 6.3% to isoniazid (INH), 2.0% to RMP (1.4% multidrug-resistant TB [MDR-TB]), 13.3% to streptomycin and 1.6% to ethambutol. Among 69 strains from previously treated cases, the prevalence of resistance was 30%, 19%, 15% (12% MDR-TB strains), 25% and 6%, respectively. CONCLUSION: Levels of drug resistance in Bujumbura are higher than average for Africa, despite long-term use of the DOTS strategy with FDCs and a ban on sales of TB drugs. Most worrying is the appearance of MDR-TB and RMP-resistant, INH-susceptible strains in new cases. Although a survey cannot prove that high HIV prevalence, elevated levels of resistance to some other drugs and irregular intake allowed acquisition of drug resistance, the effectiveness and safety of 6-month regimens with (partially) intermittent RMP throughout under such conditions should be investigated.     

Drug resistance among smear-positive tuberculosis patients in Ho Chi Minh City, Vietnam.

OBJECTIVES: To assess the pattern of drug resistance among smear-positive tuberculosis (TB) patients in an inner city area in Vietnam. METHODS: A random sample of patients diagnosed by the national TB programme (NTP) were offered HIV testing and submitted sputum for Mycobacterium tuberculosis drug sensitivity testing. RESULTS: Of 1433 isolates from new patients, 360 (25%) were resistant to isoniazid (INH), 57 (4.0%) to rifampicin (RMP), 421 (29%) to streptomycin (SM) and 28 (2.0%) to ethambutol. Among 401 previously treated patients, this was 218 (54%), 109 (27%), 217 (54%) and 26 (7%), respectively. Multidrug resistance (MDR) was observed in 55 (3.8%) new and 102 (25%) previously treated patients. RMP resistance was strongly associated with resistance to INH (OR 46) and INH plus SM (OR 91, P = 0.004). Prevalence of drug resistance tended to decrease with age. Neither any resistance nor MDR was significantly associated with HIV infection. CONCLUSIONS: In this inner city area, levels of drug resistance, in particular of MDR among previously treated patients, are high. This may be related to the use of NTP regimens in the context of highly prevalent combined SM and INH resistance which may favour acquisition of RMP resistance.     

Surveillance of Mycobacterium tuberculosis drug resistance in Hong Kong, 1986-1999, after the implementation of directly observed treatment.

OBJECTIVE: To study changing trends in TB epidemiology with emphasis on drug resistance rates in various age groups from 1986-1999. DESIGN: Laboratory-based data on drug susceptibility testing against streptomycin (SM), isoniazid (NH), rifampicin (RMP) and ethambutol (EMB) had been collected continuously in a centralised TB laboratory in Hong Kong. Epidemiological parameters such as sex, age and drug resistance rates in new and retreatment cases were measured and analysed for longitudinal trends. RESULTS: Of 48 924 non-duplicate isolates from new TB cases, 7045 (14.4%) were resistant to one or more drugs, 5773 (11.8%) were resistant to SM and/or INH while 881 (1.8%) were multidrug-resistant (MDR-TB). Of 3857 isolates from retreatment patients, 1176 (30.5%) were resistant to one or more drugs, 616 (16.0%) were resistant to SM and/or [NH, and 467 (12.1%) were MDR-TB. For isolates from new cases, significant declines were observed in the resistance rates against any drug, SM alone, INH alone, SM+INH and INH+RMP. For retreatment isolates, significant declines were also observed in resistance to any drug and INH+RMP. In both new and retreatment cases, isolates from patients aged over 65 years showed significantly lower drug resistance (any drug and INH+RMP) compared with other age groups (16-34 years and 35-65 years). CONCLUSION: With successful implementation of DOTS over a 14-year period, laboratory-based surveillance data showed significant declines in drug resistance, including MDR-TB. This has occurred amidst demographic changes associated with a generally ageing population as well as highly mobile sectors that are in constant exchange with highly endemic areas.     

Impact of drug-resistant tuberculosis on the survival of HIV-infected patients.

OBJECTIVE: To determine the effect of drug-resistant tuberculosis (TB) on the survival of human immunodeficiency virus (HIV) infected patients in an area with a high prevalence of TB. DESIGN: Retrospective cohort study. RESULTS: Of 225 HIV-TB patients with a mean age of 35.8 years, 72.4% were male. The median CD4 cell count at TB diagnosis was 44 cells/mm3. Sixty per cent presented with extra-pulmonary TB (EPTB). Sixty-three (28%) patients were infected with Mycobacterium tuberculosis resistant to at least one drug; respectively 16.4%, 9.3%, 5.3% and 12.9% were resistant to isoniazid (INH), rifampicin (RMP), ethambutol and streptomycin, and 14 (6.2%) had multidrug-resistant TB (MDR-TB). During a median follow-up of 11.5 months, 4% died. From Kaplan-Meier analysis, INH resistance, RMP resistance and MDR-TB were associated with shorter survival (log-rank test, P < 0.005). Cox's proportional hazard model showed that MDR-TB (hazard ratio [HR] 11.7; 95% CI 2.1-64.9), not receiving antiretroviral therapy (ART) (HR 7.9; 95% CI 1.5-43.1) and EPTB (HR 5.1; 95% CI 1.9-25.9) were significant risk factors for death. CONCLUSION: MDR-TB and EPTB substantially reduce survival among patients co-infected with HIV and TB. Early detection and optimal treatment of MDR-TB are crucial. ART significantly prolongs survival and should be initiated in HIV-TB co-infected patients.     

Primary and acquired drug resistance in Polish tuberculosis patients: results of a study of the national drug resistance surveillance programme.

OBJECTIVE: To determine the prevalence and patterns of primary and acquired drug resistance among Mycobacterium tuberculosis isolates recovered from tuberculosis patients in Poland. DESIGN: In a prospective survey, M. tuberculosis strains were collected from 3970 tuberculosis patients (2976 newly diagnosed cases and 994 previously treated patients) bacteriologically confirmed by culture between November 1996 and October 1997. METHODS: Drug susceptibility testing to isoniazid (INH), streptomycin, ethambutol and rifampicin (RMP) was performed on L?wenstein-Jensen medium according to the proportion method and/or using the radiometric Bactec 460 TB system. RESULTS AND CONCLUSION: The male to female ratio was 2.61:1. The patients were aged between 6 and 82 years, with 86% of males and 77% of females aged over 35 years. Primary resistance to any drug was found in 3.6% of new patients; any INH resistance was 2.6%, any RMP resistance was 0.7%, and multidrug resistance (to INH and RMP [MDR]) was 0.6%. In previously treated cases, resistance to any drug was 17.0%, any INH resistance 14.1%, any RMP resistance 7.8%, and MDR 7.0%. Drug-resistant tuberculosis does not present a big problem in Poland; primary drug resistance has been monitored since 1960 with decreasing frequency, and rates remain at the same level as 20 years ago. Studies such as this should be conducted regularly to monitor drug resistance in Poland in order to effectively manage national tuberculosis control efforts.     

Surveillance of anti-tuberculosis drug resistance in Ernakulam District, Kerala State, South India.

SETTING: This is the first report on drug resistance surveillance (DRS) in Ernakulam District, Kerala, South India, based on a standard protocol from World Health Organization (WHO) guidelines. OBJECTIVES: To determine the level of drug resistance among smear-positive pulmonary tuberculosis (PTB) patients with no history of previous treatment in Ernakulam District, Kerala State. DESIGN: Two additional sputum samples were collected from all consecutive new smear-positive PTB cases registered under the revised National TB Control Programme (RNTCP) formulated by the Government of India. The generic protocol developed by the Central TB Division for district level DRS in accordance with WHO guidelines was followed. Training of laboratory staff and other health personnel, periodic monitoring and quality assurance of laboratory work were carried out by the Tuberculosis Research Centre, Chennai. RESULTS: A total of 305 (88.7%) sputum samples were positive for culture. Resistance to any drug was seen in 27.9% and multidrug-resistant tuberculosis (MDR-TB) was observed in 2%. Monoresistance to rifampicin and streptomycin was observed in respectively 1% and 17% of cases, and 27.1% resistance was observed to any drug in the younger age group. CONCLUSION: MDR-TB is within expected ranges in Ernakulam District. Further studies that include the private sector are needed in the state among different age groups.     

Characterization of clinical isolates of Mycobacterium tuberculosis resistant to drugs and detection of RpoB mutation in multidrug-resistant tuberculosis in the Philippines.

SETTING: Retrospective study of Mycobacterium tuberculosis isolates at the STD/AIDS Cooperative Central Laboratory, Philippines. OBJECTIVE: To describe patterns of M. tuberculosis resistance against first-line anti-tuberculosis drugs, and to analyze the rpoB gene codon mutation of rifampicin (RMP) resistant isolates and correlate genotypic and phenotypic patterns. DESIGN: One hundred and sixty-four M. tuberculosis complex isolates were retrieved for phenotypic analysis; 89 were resistant to any anti-tuberculosis drug and 50 were RMP-resistant, whereas 48 were multidrug-resistant (MDR). Of these 48, only 33 were available for genotypic analysis of the rpoB gene. RESULTS: Most drug-resistant isolates were phenotypically resistant to isoniazid (INH) (93%), and the probability of an RMP-resistant isolate becoming MDR was 96%. In 33 MDR isolates, 13 types of mutations in nine independent codons were identified; the most frequently mutated codons were S531L (61%) and G510H (15%), which were present in 76% (25/33) of the isolates. S531L was noted in 85.7% of the RMP + INH + SM resistant isolates, while only 80% of the isolates with INH + RMP, EMB + SM resistance showed this mutation. CONCLUSION: The high probability of RMP isolates being MDR suggests that genetic analysis of RMP resistance is useful in detecting MDR-TB. Worldwide accumulation of findings on circulating MDR-TB strains provides indispensable information about the re-emergence of TB.     

Validation of a rapid method for detection of M. tuberculosis resistance to isoniazid and rifampin in Lima, Peru.

SETTING: Treatment of multidrug-resistant tuberculosis (MDR-TB) is often based on drug susceptibility testing (DST) results; for this reason, rapid, simple DST methods are sought which could be applied in resource-poor countries. One such method is a nitrate reductase colorimetric assay known as the Griess method. In Peru, where the incidence rate of TB is among the highest in South America, the National Institute of Health recently undertook the validation and implementation of the direct Griess method. OBJECTIVE: To describe the process of validation and implemention of the direct Griess method at the Peruvian National Institute of Health. DESIGN: Prospective study comparing the sensitivity and specificity of the direct Griess method with the L?wenstein-Jensen proportion method in determining resistance to isoniazid (INH) and rifampin (RMP) among clinical isolates. RESULTS: Among 192 specimens, the sensitivity and specificity of the Griess method for detection of INH resistance was 99.1% and 100%, respectively. For identification of RMP resistance, the sensitivity and specificity was 93.5% and 100%, respectively. CONCLUSIONS: In addition to its high sensitivity and specificity and rapid turn around time, the Griess method uses simple, inexpensive reagents and requires minimal laboratory space and technical expertise, thus providing an ideal screening tool for resource-poor settings with high rates of MDR-TB.     

Global isoniazid resistance patterns in rifampin-resistant and rifampin-susceptible tuberculosis

Following the World Health Organization's endorsement of the Xpert? MTB/RIF assay, which rapidly and simultaneously diagnoses tuberculosis (TB) and detects resistance to rifampin (RMP), the question arises to what extent RMP resistance is an adequate marker for multidrug-resistant TB (MDR-TB). A retrospective analysis of data from >81 countries and subnational settings demonstrated that >40% of RMP-resistant isolates from new TB cases did not display resistance to isoniazid (INH) in settings with relatively low MDR-TB prevalence (one third of all countries and subnational settings). Results indicated the need for INH susceptibility testing in addition to RMP susceptibility testing.     

Prevalence of drug resistance under the DOTS strategy in Hyderabad, South India, 2001-2003.

BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB), defined as resistance to at least isoniazid (INH) and rifampicin (RMP), is considered a threat to TB control. Implementation of DOTS ensures high cure rates and prevents MDR. OBJECTIVE: To study the prevalence of MDR-TB from a retrospective analysis of the data in a tuberculosis unit where DOTS was implemented over a period of 6 years through public private mix (PPM). METHODS: Drug susceptibility testing of Mycobacterium tuberculosis samples isolated from the cultures of newly registered and retreatment sputum smear-positive cases during 2001-2003. RESULTS: During the study, 909 sputum-positive cases were registered and analysed. Of these, 714 were new and 195 were retreatment sputum-positive cases. INH resistance was found in 3.2% (23) of new and 9.2% (18) of retreatment cases. RMP resistance was present in 1.5% (11) of new and 7.2% (14) of retreatment cases. MDR was present only in 0.14% (1) of new and 2% (4) of retreatment cases. New cases had cure rates of 96% compared to 85% in retreatment cases. CONCLUSION: The prevalence of MDR-TB is low where success rates are high.     

Prevalence of drug-resistant tuberculosis in an HIV endemic area in northern Thailand.

SETTING: Chiang Rai Province in Northern Thailand, where human immunodeficiency virus (HIV) infection has been prevalent since the 1990s. OBJECTIVE: To observe the prevalence of drug-resistant tuberculosis (TB) and investigate the factors related to the level of drug resistance in an HIV endemic area. DESIGN: Population-based surveillance study covering the whole province. METHOD: Drug susceptibility testing was performed at the Thai Ministry of Public Health laboratory for all sputum smear-positive TB patients diagnosed in hospitals in Chiang Rai Province over a 25-month period in 1996-1998. Patient characteristics were obtained through interview by trained personnel. HIV testing was performed with informed consent. RESULTS: Among the 1077 incident patients without previous history of treatment, the proportion of patients with resistance to isoniazid was 13.2%, 10.8% to rifampicin, 15.6% to streptomycin, and 5.8% to ethambutol. Multidrug resistance (MDR), i.e., resistance to at least both isoniazid and rifampicin, was observed in 6.3%. Factors associated with primary MDR-TB were HIV positivity (OR 2.2, 95%CI 1.3-3.9), age <50 years (OR 2.0), and treatment in the provincial hospital (OR 2.3), compared to patients treated in the community and private hospitals. Stratified analysis shows a significantly high prevalence of primary MDR-TB among HIV-positive patients treated in the provincial hospital against HIV-negative patients or HIV-positive patients in other hospitals. CONCLUSION: The prevalence of primary MDR-TB in this area was high. It is necessary to strengthen TB control activities in order to reduce the burden of MDR-TB.     

Drug resistance of Mycobacterium tuberculosis in the Sunamganj District of Bangladesh

Spread of drug-resistant tuberculosis (TB) threatens TB-control programmes, and all countries need to monitor the patterns and trends of anti-TB drug resistance. Such data assess the quality of control programmes and help forecast future trends of drug resistance. It will also help to establish guidelines for TB therapy. The aim of the current study was to describe the rate of drug-resistant Mycobacterium tuberculosis in the Sunamganj District of Bangladesh. Bacterial isolates were collected from sputum smear positive (ss+) patients who attended the National TB Programme from November 2003 to December 2004. A total of 95 isolates was tested for susceptibility to streptomycin (SM), isoniazid (INH), rifampicin (RMP) and ethambutol (EMB) at the National Reference Laboratory for Mycobacteria at the Norwegian Institute of Public Health (NIPH), Oslo. The total resistance among new cases to any drug was 31%. For SM it was 18%, INH 23%, RMP 2%, EMB 10% and 2% were multidrug-resistant (MDR). The National Tuberculosis Programme (NTP) in Sunamganj is still effective, although the high resistance to INH is alarming. An increased risk of treatment failure has been demonstrated in areas with high levels of INH resistance, and a high proportion of INH resistant cases may develop resistance to RMP during treatment.     

Prevalence of primary multidrug resistance to anti-tuberculosis drugs in Pakistan.

SETTING: Pakistan ranks sixth in the world in terms of tuberculosis (TB) burden, with a World Health Organization estimated incidence of 181 per 100000, or 286000 new cases annually. Hospital-based data indicate a significant problem of multidrug-resistant TB (MDR-TB) in the country and highlight the need to assess its extent at community level. In this cross-sectional study, sputum samples from 742 untreated newly diagnosed pulmonary TB patients from all over the country were used. OBJECTIVE: To assess the prevalence of primary drug resistance in Pakistan. RESULTS: Of 672 culture-positive patients, 76 (11.3%) showed resistance to one or more drugs. Resistance to streptomycin (10 microg/ml) was found in 36 (5.4%) patients, isoniazid (INH) (1 microg/ml) in 51 (7.6%), rifampicin (RMP) (5 microg/ml) in 15 (2.2%), ethambutol (10 microg/ml) in 12 (1.8%) and pyrazinamide in 22 (3.3%) samples. Forty-six (6.8%) of the isolates tested were resistant to a single drug, 10 (1.5%) to two drugs, 12 (1.8%) to three drugs, and 6 (0.9%) to four drugs, while 2 (0.3%) isolates were resistant to all five first-line agents. Primary MDR-TB was 1.8% (n=12) (INH 1 microg/ml, RMP 5 microg/ml). CONCLUSION: The results of this study show a prevalence of primary MDR-TB in Pakistan of <2%, which needs to be addressed through an effective DOTS strategy.     

Prevalence and risk factors associated with drug resistant TB in South West, Nigeria

ObjectiveTo determine the prevalence and risk factors associated with drug resistant tuberculosis (TB) in South West Nigeria.MethodsA retrospective study conducted among pulmonary tuberculosis (PTB) patients from Oyo and Osun States in South West Nigeria who had their culture and drug susceptibility test performed at the institute of tropical medicine Antwerp, Belgium between 2007 and 2009. Data on the patient's characteristics were retrieved from the TB treatment card. Univariate analysis was performed to assess the risk factors for drug resistant tuberculosis. The Level of significance was at P<0.05.ResultsAmong the 88 patients who had drug-susceptibility test result, there were 50 males and 38 females. Of the 88 patients, 55 (62.5%) had strains resistant to at least one or more anti-drugs. The proportion of TB cases with resistance to a single drug was 12.7%. The multi-drug resistant TB (MDR-TB) rate was 76.4%. The only significant factor for the development of drug resistance and MDR was the history of previous anti TB treatment (P<0.01). Other factors such as age [OR 0.86 (0.35?2.13); P=0.72] and gender [OR 1.24 (0.49?3.14); P=0.62] were not significantly associated with drug resistance TB.ConclusionsThe study highlighted a high prevalence of MDR-TB among the study population. History of previous TB treatment was associated with MDR-TB. There is an urgent need to conduct a national TB drug resistance survey to determine the actual burden and risk factors associated with drug resistance TB in the country.     

Secular trends in susceptibility patterns of Mycobacterium tuberculosis isolates in Kuwait, 1996-2005

OBJECTIVE: To determine the incidence and trends of drug resistance among all Mycobacterium tuberculosis strains isolated during a 10-year period in Kuwait. DESIGN: Drug susceptibility data for M. tuberculosis isolates recovered from all pulmonary and extra-pulmonary tuberculosis (TB) patients in Kuwait from January 1996 to December 2005 were collected and analysed. Patients were divided into Kuwaiti nationals and expatriates. Prior treatment status was not recorded. RESULTS: From 1996 to 2005, 5399 non-repetitive culture-positive TB cases (56% from pulmonary sites and 44% from extra-pulmonary sites) among 917 (17%) Kuwaiti nationals and 4482 (83%) expatriates were identified throughout Kuwait. Overall resistance rates were as follows: any drug 12.5%, isoniazid (INH) 9.1%; rifampicin (RMP) 1.1%, ethambutol (EMB) 2.0%, streptomycin 4.3% and multidrug resistance (MDR) 0.9%. The resistance rates over the 10-year period remained nearly same. However, significant differences were noted in resistance rates for RMP and MDR among pulmonary vs. extra-pulmonary cases and for any drug, INH and EMB among isolates from Kuwaiti vs. expatriate patients. CONCLUSIONS: Moderate and stable single drug resistance (<10%) and low MDR rates (<1%) were found among TB cases in Kuwait. These findings highlight the importance of ongoing control measures to limit the development and spread of drug-resistant M. tuberculosis in Kuwait.