Antibiotic resistant tuberculosis in the United Kingdom: 1993-1999

Risk factors for treatment failure in multidrug resistant tuberculosis in Tunisia: An analytic study

INTRODUCTION-AIM

The emergence of multidrug resistant tuberculosis (MDR-TB) is a threat to global public health. The aim of our study was to determine risk factors for treatment failure in MDR-TB.

METHODS

Retrospective study conducted between January 2000 and March 2019 including patients with MDR-TB. Characteristics of patients with therapeutic failure were compared to cured ones. Logistic regression analysis was used to identify risk factors for treatment failure.

RESULTS

Our study included 140 patients aged of 42±13 years (18-80). Fifty-seven percent of patients had treatment success and 12% had treatment failure. In multivariate logistic regression analysis, treatment failure was associated with age over 45 years (OR=1.05; 95%CI, 1.024-7.736;p=0.014), primary education level and illiteracy (OR=5.022; 95%CI, 1.316-19.161;p=0,018), history of incarceration (OR=3.291; 95%CI, 1.291-21.083;p=0.016), undernutrition (OR=4.544; 95%CI, 2.304-54.231;p=0,027), extensive TB (OR=6.406; 95%CI, 1.761-23.922; p=0.038), initial high grade positive smears (OR=1.210; 95%CI, 1.187-32.657; p=0.045), positive smear culture at 90 days of treatment (OR=6.871, 95%CI, 3.824-23.541; p=0.003), poor adherence (OR=6.110; 95%CI, 2.740-12.450; p=0.021) and occurrence of psychiatric adverse events (OR=3.644 95%CI, 2.560- 27.268; p=0.041).

CONCLUSION

Therapeutic education, nutritional and psychological support and close follow-up are strongly recommended to optimize the prognosis of MDR-TB.

The impact of diabetes mellitus on the emergence of multi-drug resistant tuberculosis and treatment failure in TB-diabetes comorbid patients: a systematic review and meta-analysis

Background

The existence of Type 2 Diabetes Mellitus (DM) in tuberculosis (TB) patients is very dangerous for the health of patients. One of the major concerns is the emergence of MDR-TB in such patients. It is suspected that the development of MDR-TB further worsens the treatment outcomes of TB such as treatment failure and thus, causes disease progression.

Aim

To investigate the impact of DM on the Emergence of MDR-TB and Treatment Failure in TB-DM comorbid patients.

Methodology

The PubMed database was systematically searched until April 03, 2022 (date last searched). Thirty studies met the inclusion criteria and were included in this study after a proper selection process.

Results

Tuberculosis-Diabetes Mellitus patients were at higher risk to develop MDR-TB as compared to TB-non-DM patients (HR 0.81, 95% CI: 0.60-0.96, p < 0.001). Heterogeneity observed among included studies was moderate (I2 = 38%). No significant change was observed in the results after sub-group analysis by study design (HR 0.81, 95% CI: 0.61-0.96, p < 0.000). In the case of treatment failure, TB-DM patients were at higher risk to experience treatment failure rates as compared to TB-non-DM patients (HR 0.46, 95% CI: 0.27-0.67, p < 0.001).

Conclusion

The results showed that DM had a significant impact on the emergence of MDR-TB in TB-diabetes comorbid patients as compared to TB-non-DM patients. DM enhanced the risk of TB treatment failure rates in TB-diabetes patients as compared to TB-non-DM patients. Our study highlights the need for earlier screening of MDR-TB, thorough MDR-TB monitoring, and designing proper and effective treatment strategies to prevent disease progression.

Global prevalence of drug-resistant tuberculosis: a systematic review and meta-analysis

BACKGROUND

Tuberculosis is a bacterial infectious disease, which affects different parts of a human body, mainly lungs and can lead to the patient's death. The aim of this study is to investigate the global prevalence of drug-resistant tuberculosis using a systematic review and meta-analysis.

METHODS

In this study, the PubMed, Scopus, Web of Science, Embase, ScienceDirect and Google Scholar repositories were systematically searched to find studies reporting the global prevalence of drug-resistant tuberculosis. The search did not entail a lower time limit, and articles published up until August 2022 were considered. Random effects model was used to perform the analysis. The heterogeneity of the studies was examined with the I² test. Data analysis was conducted within the Comprehensive Meta-Analysis software.

RESULTS

In the review of 148 studies with a sample size of 318,430 people, the I² index showed high heterogeneity (I² = 99.6), and accordingly random effects method was used to analyze the results. Publication bias was also examined using the Begg and Mazumdar correlation test which indicated the existence of publication bias in the studies (P = 0.008). According to our meta-analysis, the global pooled prevalence of multi-drug resistant TB is 11.6% (95% CI: 9.1-14.5%).

CONCLUSIONS

The global prevalence of drug-resistant tuberculosis was found to be very high, thus health authorities should consider ways to control and manage the disease to prevent a wider spread of tuberculosis and potentially subsequent deaths.

Drug-Resistant Tuberculosis Among Children: A Systematic Review and Meta-Analysis

Background: Drug-resistant tuberculosis (DR-TB), especially multidrug-resistant tuberculosis (MDR-TB) is a public health threat. Little is known about estimates of different profiles and rates of DR-TB among children globally. Methods: We did a systematic review and meta-analysis of observational studies reporting DR-TB among children by searching Embase, PubMed, and Scopus databases from January 1, 2000 to October 1, 2020. Publications reporting more than 60 children with bacteriological confirmed tuberculosis and phenotypical drug susceptibility testing (DST) results were included. Pooled proportions of MDR-TB and sub-analysis by age subgroups, regions, economical levels were performed. Results: We identified 4,063 studies, of which 37 were included. Of 23,652 pediatric TB patients, the proportions of DR-TB, MDR-TB, mono-resistant TB, polydrug resistant TB, extensively drug-resistant TB were 13.59% (1,964/14,453), 3.72% (881/23,652), 6.07% (529/8,719), 1.61% (119/7,361), 0.44% (30/6,763), respectively. The pooled proportion of MDR-TB among 23,652 children of 37 studies was 3.7% (95% CI, 3.5-4.0%). Rate of MDR-TB was much lower in high-income countries (1.8%) than that in lower-middle-income countries (6.3%) and upper-middle-income countries (7.3%). More specifically, the rates of MDR-TB were 1.7% in USA, 1.7% in UK, 2.9% in India, 6.0% in South Africa, 9.8% in China, respectively. Conclusions: The burden of DR-TB remains high in children, and there are potential associations between rates of pediatric MDR-TB and national economical levels. More interventions on child TB cases in low-income countries may be urgently needed in future.

Analysis of novel fractional COVID-19 model with real-life data application

The current work is of interest to introduce a detailed analysis of the novel fractional COVID-19 model. Non-local fractional operators are one of the most efficient tools in order to understand the dynamics of the disease spread. For this purpose, we intend as an attempt at investigating the fractional COVID-19 model through Caputo operator with order χ ∈ ( 0 , 1 ) . Employing the fixed point theorem, it is shown that the solutions of the proposed fractional model are determined to satisfy the existence and uniqueness conditions under the Caputo derivative. On the other hand, its iterative solutions are indicated by making use of the Laplace transform of the Caputo fractional operator. Also, we establish the stability criteria for the fractional COVID-19 model via the fixed point theorem. The invariant region in which all solutions of the fractional model under investigation are positive is determined as the non-negative hyperoctant R + 7 . Moreover, we perform the parameter estimation of the COVID-19 model by utilizing the non-linear least squares curve fitting method. The sensitivity analysis of the basic reproduction number R 0 c is carried out to determine the effects of the proposed fractional model's parameters on the spread of the disease. Numerical simulations show that all results are in good agreement with real data and all theoretical calculations about the disease.

Fractional methicillin-resistant Staphylococcus aureus infection model under Caputo operator

This study provides a detailed exposition of in-hospital community-acquired methicillin-resistant S. aureus (CA-MRSA) which is a new strain of MRSA, and hospital-acquired methicillin-resistant S. aureus (HA-MRSA) employing Caputo fractional operator. These two strains of MRSA, referred to as staph, have been a serious problem in hospitals and it is known that they give rise to more deaths per year than AIDS. Hence, the transmission dynamics determining whether the CA-MRSA overtakes HA-MRSA is analyzed by means of a non-local fractional derivative. We show the existence and uniqueness of the solutions of the fractional staph infection model through fixed-point theorems. Moreover, stability analysis and iterative solutions are furnished by the recursive procedure. We make use of the parameter values obtained from the Beth Israel Deaconess Medical Center. Analysis of the model under investigation shows that the disease-free equilibrium existing for all parameters is globally asymptotically stable when both R 0 H and R 0 C are less than one. We also carry out the sensitivity analysis to identify the most sensitive parameters for controlling the spread of the infection. Additionally, the solution for the above-mentioned model is obtained by the Laplace-Adomian decomposition method and various simulations are performed by using convenient fractional-order α .

Primary Drug-Resistance Pattern and Trend in Elderly Tuberculosis Patients in Shandong, China, from 2004 to 2019

BACKGROUND

With an aging population, China is facing a huge burden of elderly patients with drug resistant tuberculosis (DR-TB), which has become a significant obstacle for the global TB control. There is still little study on DR-TB in the elderly in China so far. Thus, more research on the epidemiological characteristics and trend of primary DR-TB among the elderly will be necessary.

METHODS

A retrospective study was conducted in Shandong, China from 2004 to 2019. We collected 12,661 primary TB cases, of which 4368 elderly (≥60 years) primary TB cases were involved. Clinical characteristics including age, sex, cavity, smoking, drinking, comorbidity and drug susceptibility data were collected from 36 TB prevention and control institutions of Shandong Province. Sputum samples were collected by each surveillance site, and examined in the TB Reference Laboratory of SPCH. Descriptive statistical analysis, chi-square and linear regression were used for analyzing.

RESULTS

Among 4368 elderly patients with primary TB, the DR-TB and multi-resistant tuberculosis (MDR-TB) accounted for 17.19% and 2.29%, respectively. During 2004-2019, the proportions of MDR-TB, polydrug resistant tuberculosis (PDR-TB), rifampin (RFP)-resistance increased by 160.00%, 18.18%, 231.82%, respectively and the rate of DR-TB among elderly patients with primary cavitary TB increased by 255%. Among the elderly with primary DR-TB during 2004-2019, the proportion of male (from 85.19 to 89.06), cavity (from 7.41 to 46.88), RFP-resistance (from 3.70 to 21.88), and streptomycin (SM)-resistance (from 37.04 to 62.5) increased significantly (P<0.05). And the proportion of female (from 14.81 to 10.94), non-cavity (from 92.59 to 32.81), INH-resistance (from 66.67 to 57.81) decreased significantly (P<0.05).

CONCLUSION

Among the elderly, the proportions of MDR-TB, PDR-TB, RFP-resistance and cavitary DR-TB increased significantly. The pattern of DR-TB changed from female, non-cavity and INH-resistant groups to male, cavity, RFP or SM-resistant groups. For a better control on the elderly DR-TB in the future, we should pay more attention to male, smoking, drinking, chronic obstructive pulmonary disease (COPD) and diabetes subgroups and take targeted measures to control these subgroups.

Exploring the effects of BCG vaccination in patients diagnosed with tuberculosis: Observational study using the Enhanced Tuberculosis Surveillance system

BACKGROUND

Bacillus Calmette-Guérin (BCG) is one of the most widely-used vaccines worldwide. BCG primarily reduces the progression from infection to disease, however there is evidence that BCG may provide additional benefits. We aimed to investigate whether there is evidence in routinely-collected surveillance data that BCG vaccination impacts outcomes for tuberculosis (TB) cases in England.

METHODS

We obtained all TB notifications for 2009-2015 in England from the Enhanced Tuberculosis surveillance system. We considered five outcomes: All-cause mortality, death due to TB (in those who died), recurrent TB, pulmonary disease, and sputum smear status. We used logistic regression, with complete case analysis, to investigate each outcome with BCG vaccination, years since vaccination and age at vaccination, adjusting for potential confounders. All analyses were repeated using multiply imputed data.

RESULTS

We found evidence of an association between BCG vaccination and reduced all-cause mortality (aOR:0.76 (95%CI 0.64-0.89), P:0.001) and weak evidence of an association with reduced recurrent TB (aOR:0.90 (95%CI 0.81-1.00), P:0.056). Analyses using multiple imputation suggested that the benefits of vaccination for all-cause mortality were reduced after 10 years.

CONCLUSIONS

We found that BCG vaccination was associated with reduced all-cause mortality in people with TB although this benefit was less pronounced more than 10 years after vaccination. There was weak evidence of an association with reduced recurrent TB.

Diabetes mellitus and the risk of multidrug resistant tuberculosis: a meta-analysis

The high prevalence of diabetes mellitus (DM) among multidrug resistant tuberculosis (MDR-TB) patients is a serious cause for concern. We conducted a meta-analysis to determine whether DM is an independent risk factor for MDR-TB. Electronic literature searches of the PubMed, Web of Science and EMBASE databases up to July 12, 2016 were conducted. The pooled adjusted odds ratio (OR) and 95% confidence intervals (CIs) were calculated using the random effects model with STATA 12.0 software. In total 13 studies, including 9289 individuals with TB, were included in this meta-analysis. Significant association between DM and MDR-TB (OR = 1.71; 95% CI = 1.32, 2.22) was identified. Subgroup analyses showed that: 1) Pooled OR was 1.25 (95% CI: 0.82-1.91) for cross-sectional studies, and was 2.14 (95% CI: 1.51-3.02) for longitudinal studies; 2) The pooled OR was 1.69 (95% CI:1.09-2.62) for primary MDR-TB, 1.94 (95% CI:1.42-2.65) for any MDR-TB, and 0.85 for secondary MDR-TB (95% CI: 0.29-2.54); 3) DM was significantly associated with MDR-TB in both Caucasian (OR = 2.26, 95% CI: 1.66-3.07) and Asian (OR = 1.40, 95% CI: 1.01-1.95) subgroups. No evidence of publication bias was identified. In conclusion, the pooling analysis indicated that DM was an independent risk factor for MDR-TB, especially for primary MDR-TB.

A Multistrain Mathematical Model To Investigate the Role of Pyrazinamide in the Emergence of Extensively Drug-Resistant Tuberculosis

Several infectious diseases of global importance—e.g., HIV infection and tuberculosis (TB)—require prolonged treatment with combination antimicrobial regimens typically involving high-potency core agents coupled with additional companion drugs that protect against the de novo emergence of mutations conferring resistance to the core agents. Often, the most effective (or least toxic) companion agents are reused in sequential (first-line, second-line, etc.) regimens. We used a multistrain model of Mycobacterium tuberculosis transmission in Southeast Asia to investigate how this practice might facilitate the emergence of extensive drug resistance, i.e., resistance to multiple core agents. We calibrated this model to regional TB and drug resistance data using an approximate Bayesian computational approach. We report the proportion of data-consistent simulations in which the prevalence of pre-extensively drug-resistant (pre-XDR) TB—defined as resistance to both first-line and second-line core agents (rifampin and fluoroquinolones)—exceeds predefined acceptability thresholds (1 to 2 cases per 100,000 population by 2035). The use of pyrazinamide (the most effective companion agent) in both first-line and second-line regimens increased the proportion of simulations in which the prevalence exceeded the pre-XDR acceptability threshold by 7-fold compared to a scenario in which patients with pyrazinamide-resistant TB received an alternative drug. Model parameters related to the emergence and transmission of pyrazinamide-resistant TB and resistance amplification were among those that were the most strongly correlated with the projected pre-XDR prevalence, indicating that pyrazinamide resistance acquired during first-line treatment subsequently promotes amplification to pre-XDR TB under pyrazinamide-containing second-line treatment. These findings suggest that the appropriate use of companion drugs may be critical to preventing the emergence of strains resistant to multiple core agents.

Mechanisms of first-line antimicrobial resistance in multi-drug and extensively drug resistant strains of Mycobacterium tuberculosis in KwaZulu-Natal, South Africa

BACKGROUND

In South Africa, drug resistant tuberculosis is a major public health crisis in the face of the colossal HIV pandemic.

METHODS

In an attempt to understand the distribution of drug resistance in our setting, we analysed the rpoB, katG, inhA, pncA and embB genes associated with resistance to key drugs used in the treatment of tuberculosis in clinical isolates of Mycobacterium tuberculosis in the KwaZulu-Natal province.

RESULTS

Classical mutations were detected in the katG, inhA and embB genes associated with resistance to isoniazid and ethambutol. Diverse mutations were recorded in the multidrug resistant (MDR) and extensively drug resistant (XDR) isolates for the rpoB and pncA gene associated with resistance to rifampicin and pyrazinamide.

CONCLUSIONS

M.tuberculosis strains circulating in our setting display a combination of previously observed mutations, each mediating resistance to a different drug. The MDR and XDR TB isolates analysed in this study displayed classical mutations linked to INH and EMB resistance, whilst diverse mutations were linked to RIF and PZA resistance. The similarity of the XDR strains confirms reports of the clonality of the XDR epidemic. The successful dissemination of the drug resistant strains in the province underscores the need for rapid diagnostics to effectively diagnose drug resistance and guide treatment.

A Global Perspective on Pyrazinamide Resistance: Systematic Review and Meta-Analysis

BACKGROUND

Pyrazinamide (PZA) is crucial for tuberculosis (TB) treatment, given its unique ability to eradicate persister bacilli. The worldwide burden of PZA resistance remains poorly described.

METHODS

Systematic PubMed, Science Direct and Scopus searches for articles reporting phenotypic (liquid culture drug susceptibility testing or pyrazinamidase activity assays) and/or genotypic (polymerase chain reaction or DNA sequencing) PZA resistance. Global and regional summary estimates were obtained from random-effects meta-analysis, stratified by presence or risk of multidrug resistant TB (MDR-TB). Regional summary estimates were combined with regional WHO TB incidence estimates to determine the annual burden of PZA resistance. Information on single nucleotide polymorphisms (SNPs) in the pncA gene was aggregated to obtain a global summary.

RESULTS

Pooled PZA resistance prevalence estimate was 16.2% (95% CI 11.2-21.2) among all TB cases, 41.3% (29.0-53.7) among patients at high MDR-TB risk, and 60.5% (52.3-68.6) among MDR-TB cases. The estimated global burden is 1.4 million new PZA resistant TB cases annually, about 270,000 in MDR-TB patients. Among 1,815 phenotypically resistant isolates, 608 unique SNPs occurred at 397 distinct positions throughout the pncA gene.

INTERPRETATION

PZA resistance is ubiquitous, with an estimated one in six incident TB cases and more than half of all MDR-TB cases resistant to PZA globally. The diversity of SNPs across the pncA gene complicates the development of rapid molecular diagnostics. These findings caution against relying on PZA in current and future TB drug regimens, especially in MDR-TB patients.

Incidence of multidrug-resistant tuberculosis disease in children: systematic review and global estimates

BACKGROUND

Multidrug-resistant tuberculosis threatens to reverse recent reductions in global tuberculosis incidence. Although children younger than 15 years constitute more than 25% of the worldwide population, the global incidence of multidrug-resistant tuberculosis disease in children has never been quantified. We aimed to estimate the regional and global annual incidence of multidrug-resistant tuberculosis in children.

METHODS

We developed two models: one to estimate the setting-specific risk of multidrug-resistant tuberculosis among child cases of tuberculosis, and a second to estimate the setting-specific incidence of tuberculosis disease in children. The model for risk of multidrug-resistant tuberculosis among children with tuberculosis needed a systematic literature review. We multiplied the setting-specific estimates of multidrug-resistant tuberculosis risk and tuberculosis incidence to estimate regional and global incidence of multidrug-resistant tuberculosis disease in children in 2010.

FINDINGS

We identified 3403 papers, of which 97 studies met inclusion criteria for the systematic review of risk of multidrug-resistant tuberculosis. 31 studies reported the risk of multidrug-resistant tuberculosis in both children and treatment-naive adults with tuberculosis and were used for evaluation of the linear association between multidrug-resistant disease risk in these two patient groups. We identified that the setting-specific risk of multidrug-resistant tuberculosis was nearly identical in children and treatment-naive adults with tuberculosis, consistent with the assertion that multidrug-resistant disease in both groups reflects the local risk of transmitted multidrug-resistant tuberculosis. After application of these calculated risks, we estimated that around 999,792 (95% CI 937,877-1,055,414) children developed tuberculosis disease in 2010, of whom 31,948 (25,594-38,663) had multidrug-resistant disease.

INTERPRETATION

Our estimates underscore that many cases of tuberculosis and multidrug-resistant tuberculosis disease are not being detected in children. Future estimates can be refined as more and better tuberculosis data and new diagnostic instruments become available.

FUNDING

US National Institutes of Health, the Helmut Wolfgang Schumann Fellowship in Preventive Medicine at Harvard Medical School, the Norman E Zinberg Fellowship at Harvard Medical School, and the Doris and Howard Hiatt Residency in Global Health Equity and Internal Medicine at the Brigham and Women's Hospital.

Prevalence and characterization of drug-resistant tuberculosis in a local hospital of Northeast China

OBJECTIVES

To investigate the distribution and risk factors associated with drug-resistant tuberculosis (TB) at a local hospital in Northeast China.

METHODS

A total of 205 patients with TB were enrolled in the study from March 8, 2010 to July 13, 2011. Mycobacterium tuberculosis (MTB) strains isolated from patients were subjected to drug susceptibility testing by proportion method.

RESULTS

Among the 205 patients with MTB, 54 (26.3%) had isolates that showed resistance to at least one drug. The overall prevalence of multidrug-resistant TB (MDR-TB) was 6.8% (n = 14) (3.0% of newly diagnosed patients and 22.0% of previously treated cases). Importantly, an extensively drug-resistant TB (XDR-TB) isolate was found, which was isolated from a newly treated patient. Eleven (5.4%) were infected with a poly-resistant strain of MTB (5.5% of newly diagnosed patients and 4.9% of previously treated cases). The mono-resistance rates of isoniazid, rifampin, ethambutol, streptomycin, ofloxacin, and kanamycin were 3.4%, 1.5%, 2.4%, 3.9%, 2.4%, and 0.5%, respectively. Certain groups, including previously treated patients and male patients, were more likely to develop drug-resistant TB.

CONCLUSIONS

The results of this analysis of drug resistance in MTB reflect the situation in a local hospital and indicate that the morbidity related to TB, especially MDR-TB, is still a serious health problem. Thus, the timely detection of drug resistance is of great importance to optimize treatment and to direct infection control measures to block the transmission of MDR-TB.

Isoniazid-resistant tuberculosis in children: a systematic review

BACKGROUND

Isoniazid resistance is an obstacle to the treatment of tuberculosis disease and latent tuberculosis infection in children. We aim to summarize the literature describing the risk of isoniazid-resistant tuberculosis among children with tuberculosis disease.

METHODS

We did a systematic review of published reports of children with tuberculosis disease who had isolates tested for susceptibility to isoniazid. We searched PubMed, Embase and LILACS online databases up to January 12, 2012.

RESULTS

Our search identified 3403 citations, of which 95 studies met inclusion criteria. These studies evaluated 8351 children with tuberculosis disease for resistance to isoniazid. The median proportion of children found to have isoniazid-resistant strains was 8%; the distribution was right-skewed (25th percentile: 0% and 75th percentile: 18%).

CONCLUSIONS

High proportions of isoniazid resistance among pediatric tuberculosis patients have been reported in many settings suggesting that diagnostics detecting only rifampin resistance are insufficient to guide appropriate treatment in this population. Many children are likely receiving substandard tuberculosis treatment with empirical isoniazid-based regimens, and treating latent tuberculosis infection with isoniazid may not be effective in large numbers of children. Work is needed urgently to identify effective regimens for the treatment of children sick with or exposed to isoniazid-resistant tuberculosis and to better understand the scope of this problem.

Multidrug-resistant tuberculosis in admitted patients at a tertiary referral hospital of Bangladesh

Background

This study was set out to investigate the magnitude, patterns and molecular characterization of drug-resistant Mycobacterium tuberculosis strains at a tertiary referral hospital in Bangladesh.

Methods

Pulmonary tuberculosis (TB) patients admitted at National Institute of Diseases of the Chest and Hospital from February 2002 to September 2005 with or without previous history of TB and/or other complications were randomly interviewed. Among 265 participants enrolled, M. tuberculosis isolates from 189 patients were finally tested for susceptibility to rifampicin (RMP), isoniazid (INH), ethambutol (ETM) and streptomycin (STM). Genotyping of M. tuberculosis was done using deletion analysis and spoligotyping.

Results

Eighty-eight percent (n = 167) of the patients had history of previous anti-TB treatment while the remaining 12% were new TB cases. Of the 189 isolates, 9% were fully susceptible to the first line anti-TB drugs and 73.5% were multi-drug resistant TB. Other susceptibility results showed 79.4%, 77.2%, 76.7% and 78.8% resistance to INH, RMP, ETM and STM respectively. Multi-drug resistance was significantly higher among the 130 (78%) patients with previous history of anti-tuberculosis treatment (95% confidence interval, p = 0.001). Among the 189 analyzed isolates, 69% were classified as “modern” M. tuberculosis strains (i.e. TbD1- strains, lacking the M. tuberculosis-deletion region TbD1), whereas the remaining 31% were found to belong to the “ancestal” TbD1+ M. tuberculosis lineages. One hundred and five different spoligotype patterns were identified in which 16 clusters contained 100 strains and 89 strains had unique pattern. Strains with a spoligotype characteristic for the “Beijing” cluster were predominant (19%) and most of these strains (75%) were multi-drug resistant (MDR).

Conclusions

A high level of drug resistance observed among the re-treatment patients poses a threat of transmission of resistant strains to susceptible persons in the community. Proper counseling of patients and attention towards the completion of the anti-TB treatment is needed.

Antitubercular drug resistance in four healthcare facilities in North India

Tuberculosis (TB) is a major public-health problem in India, having the highest number of incident and multidrug-resistant (MDR) TB cases. The study was carried out to appraise the prevalence of first-line anti-TB drug resistance in Mycobacterium tuberculosis (MTB) and its patterns among different types of TB patients from different settings in a province of North India. Of 3,704 clinical specimens, 345 (9.3%) were culture-positive, and drug-susceptibility testing was carried out for 301 MTB strains. A high level of primary and acquired drug resistance of MTB was observed in the region studied, with weighted mean of 10.5% and 28.08%, 12.81% and 29.72%, 17.12% and 29.94%, 11.97% and 27.84%, and 10.74% and 23.54% for rifampicin, isoniazid, streptomycin, ethambutol-resistant and MDR cases respectively. Drug resistance was significantly higher in pulmonary (p = 0.014) and acquired drug-resistant TB cases (p < 0.001). Any drug resistance (p = 0.002) and MDR TB were significantly (p = 0.009) associated with HIV-seropositive cases. An urgent plan is needed to continuously monitor the transmission trends of drug-resistant strains, especially MDR-TB strains, in the region.

Differences in drug resistance profiles of Mycobacterium tuberculosis isolates causing pulmonary and extrapulmonary tuberculosis in a medical centre in Taiwan, 2000-2010

Few studies have investigated the drug resistance profiles of Mycobacterium tuberculosis (MTB) isolates recovered from different sites of infection. A total of 4521 non-duplicate MTB isolates, including 3723 (82.3%) from respiratory specimens and 798 (17.7%) from non-respiratory sources, were recovered from patients treated at a medical centre in Taiwan from 2000 to 2010. Trend analysis showed a significant decrease (P<0.05) in the rates of resistance to isoniazid, rifampicin and ethambutol, a decrease in resistance to any one of four agents, namely isoniazid, rifampicin, ethambutol or streptomycin, and a decrease in resistance to both isoniazid and rifampicin (multidrug resistance) amongst pulmonary MTB isolates. A similar decrease in resistance to isoniazid and ethambutol was noted amongst non-pulmonary isolates. Rates of drug resistance were significantly higher amongst MTB isolates recovered from respiratory specimens than amongst those from non-respiratory specimens to 0.2 μg/mL isoniazid (15.3% vs. 9.4%; P<0.0001), 1 μg/mL rifampicin (5.5% vs. 3.3%; P=0.0108), 5 μg/mL ethambutol (7.3% vs. 3.8%; P=0.0004), and both isoniazid and rifampicin (4.8% vs. 2.5%; P=0.0051). Resistance rates amongst isolates causing tuberculous lymphadenitis were significantly lower than amongst those causing genitourinary tuberculosis (TB) to isoniazid (3.5% vs. 19.4%, P=0.0012) and to isoniazid, rifampicin, ethambutol or streptomycin (9.6% vs. 22.6%, P=0.0003). In conclusion, the rates of resistance to first-line anti-TB agents and to multiple agents differed amongst MTB isolates obtained from different infectious sources. Continuous monitoring of resistance of MTB isolates from various sites is necessary in order to establish an effective TB surveillance programme.

Anti-tuberculosis drug resistance patterns and trends in a tuberculosis referral hospital, 1997-2009

Information about the changing epidemiology of drug-resistant tuberculosis (TB) in hospitals in China over the past decade remains largely unknown. This study examined the susceptibility patterns and trends of drug-resistant TB cases in the 309 Hospital in Beijing, China. Mycobacterium tuberculosis isolates were retrospectively identified, drug susceptibility test (DST) results and clinical data were analysed for the period 1997-2009. Of the 5523 culture-positive TB patients, 47·1% had resistance to any anti-TB drug, 14·8% had mono-resistant TB, 19·8% had poly-resistant TB, 19·4% had multidrug-resistant TB (MDR-TB), and 1·3% had extensively drug-resistant TB (XDR-TB). Drug-resistant TB was significantly associated with age group, residential situation, and TB treatment history (P<0·001). During 1997-2000, the percentage of TB patients with any resistance, mono-resistant TB, poly-resistant TB, MDR-TB and XDR-TB all increased significantly (P<0·001). During 2000-2003, the increasing trends of MDR-TB and XDR-TB cases were reversed. During 2004-2009, the percentage of TB patients with any resistance, mono-resistant TB, poly-resistant TB, MDR-TB and XDR-TB all declined significantly (P<0·001), but the prevalence of MDR-TB and poly-resistant TB cases remained high. Our study provides evidence demonstrating that intensive TB control measures have helped reverse the increasing trends of drug-resistant TB in China, but continuous surveillance of drug-resistant TB and better case management are still needed to further reduce the remaining high prevalence of drug-resistant TB.

Is HIV infection a risk factor for multi-drug resistant tuberculosis? A systematic review

Background

Tuberculosis (TB) is an important cause of human suffering and death. Human immunodeficiency virus (HIV), multi-drug resistant TB (MDR-TB), and extensive drug resistant tuberculosis (XDR-TB) have emerged as threats to TB control. The association between MDR-TB and HIV infection has not yet been fully investigated. We conducted a systematic review and meta-analysis to summarize the evidence on the association between HIV infection and MDR-TB.

Methods and Results

Original studies providing Mycobacterium tuberculosis resistance data stratified by HIV status were identified using MEDLINE and ISI Web of Science. Crude MDR-TB prevalence ratios were calculated and analyzed by type of TB (primary or acquired), region and study period. Heterogeneity across studies was assessed, and pooled prevalence ratios were generated if appropriate. No clear association was found between MDR-TB and HIV infection across time and geographic locations. MDR-TB prevalence ratios in the 32 eligible studies, comparing MDR-TB prevalence by HIV status, ranged from 0.21 to 41.45. Assessment by geographical region or study period did not reveal noticeable patterns. The summary prevalence ratios for acquired and primary MDR-TB were 1.17 (95% CI 0.86, 1.6) and 2.72 (95% CI 2.03, 3.66), respectively. Studies eligible for review were few considering the size of the epidemics. Most studies were not adjusted for confounders and the heterogeneity across studies precluded the calculation of a meaningful overall summary measure.

Conclusions

We could not demonstrate an overall association between MDR-TB and HIV or acquired MDR-TB and HIV, but our results suggest that HIV infection is associated with primary MDR-TB. Future well-designed studies and surveillance in all regions of the world are needed to better clarify the relationship between HIV infection and MDR-TB.

Trends in Mycobacterium tuberculosis resistance, Pakistan, 1990-2007

OBJECTIVE

To determine resistance trends including the emergence of extensive drug resistance (XDR) in Mycobacterium tuberculosis (MTB) isolates from Pakistan.

METHODS

This was a retrospective analysis of MTB isolates (January 1990-June 2007) collected from the four provinces of Pakistan. Standard methods were used to isolate MTB. Susceptibility against rifampin, isoniazid, streptomycin, ethambutol, ethionamide, capreomycin, cycloserine, and ciprofloxacin was tested using the agar proportion method, while susceptibility to pyrazinamide was determined using BACTEC. Resistance over the study period was assessed using Chi-square for trend analysis.

RESULTS

Resistance in 15343 MTB isolates showed a steady increase over the study period; a significant trend of increasing resistance was noted in three of the four provinces included in the study. XDR-tuberculosis was first seen in 1998; to date 22 XDR cases have been documented. MTB resistance was significantly lower (p<0.001) in patients under 5 and over 60 years of age, and significantly higher in males than females (p<0.001). MTB resistance was also higher in pulmonary than extrapulmonary isolates (p<0.001).

CONCLUSION

This study documenting a steady increase in resistance among MTB isolates and the emergence of XDR strains is concerning. The data highlight the need to ensure adequate treatment of cases in order to prevent a further increase in multidrug resistance within the country. The importance of developing systems for monitoring drug resistance through nationwide surveillance is emphasized.

First-line anti-tuberculosis drug resistance patterns and trends at the national TB referral center in Iran--eight years of surveillance

OBJECTIVE

Resistance to anti-tuberculosis (anti-TB) drugs is becoming a major and alarming threat in most regions worldwide.

METHODS

This was a descriptive cross-sectional study at a tertiary hospital in Iran, using patient medical records for 2000-2003. The findings were analyzed following the same framework as that used for previous reports from this center.

RESULTS

Among 1556 TB patients, drug susceptibility testing (DST) was performed for 548 culture-positive cases. Anti-TB drug resistance to both isoniazid and rifampin was identified in 10 (2.8%) of the new TB cases (multidrug-resistant TB; MDR-TB). Any resistance was detected in 228 (41.6%), showing an increasing trend in both new and retreatment cases. The data analysis revealed that drug-resistant TB had a statistically significant association with Afghan ethnicity, age>65 years, and the type of disease (retreatment vs. new TB case) (p<0.05). Also, assessment of the drug resistance trends showed a significant increase in resistance to any anti-TB agent, to isoniazid, and to streptomycin in new cases, and to all of the first-line anti-TB drugs in retreatment patients.

CONCLUSIONS

There has been an increasing trend in drug resistance in recent years, particularly in retreatment cases. Hence, revision of the national TB control program, reevaluation of the role of the World Health Organization category II (CAT II) regimen, as well as the conducting of a nationwide drug resistance survey, are recommended.

Drug-resistant tuberculosis in Shanghai, China, 2000-2006: prevalence, trends and risk factors

SETTING

During 2000-2006, a regional anti-tuberculosis drug resistance surveillance study was conducted in Shanghai, China.

OBJECTIVE

To determine the prevalence, trends and risk factors for drug-resistant tuberculosis (TB) in Shanghai, China.

DESIGN

A retrospective study of all pulmonary TB patients reported in Shanghai during 2000-2006 was conducted.

RESULTS

Of 8419 pulmonary TB patients, 16.6% had resistance to any first-line anti-tuberculosis drug and 4.0% had multidrug resistance (MDR). The percentage of TB patients with resistance to any first-line anti-tuberculosis drug and MDR significantly increased during 2000-2003 (P=0.01 and P<0.01, respectively). After improvements in the TB control programme in 2004, the increasing trend in drug resistance was contained. Age 30-59 years, being an urban migrant and residence in an urban area of Shanghai were independently associated with resistance to any first-line drug and MDR in new cases, while age 30-59 years and being an urban migrant were independently associated with resistance to any first-line drug and MDR in previously treated cases.

CONCLUSIONS

Drug-resistant TB and MDR-TB pose a challenge for TB control in Shanghai. Improved case management, including DOTS and appropriate treatment regimens, should be sustained to prevent further transmission and development of drug-resistant TB in this setting.

Risk factors for multidrug-resistant tuberculosis in a tuberculosis unit in Madrid, Spain

The setting for this retrospective cohort study was a specialised tuberculosis unit in Madrid, Spain. The objective was to describe the risk factors for multidrug-resistant tuberculosis (MDR-TB). The medical records of all patients admitted to the unit were reviewed retrospectively to identify factors associated with multidrug resistance. Patients with positive culture for M. tuberculosis and with available drug-susceptibility tests were included. The variables assessed were age, gender, country of origin, homelessness, alcohol consumption, intravenous drug use, methadone substitution therapy, contact with a tuberculosis patient, sputum smear, site of disease, previous tuberculosis treatment, HIV infection, history of imprisonment, diabetes mellitus and chronic obstructive pulmonary disease. Thirty patients with MDR-TB and 666 patients with non-MDR-TB were included from the years 1997 to 2006. The only factors associated with MDR-TB in multivariate analysis were previous tuberculosis treatment (OR: 3.44; 95% CI: 1.58-7.50; p = 0.003), age group 45-64 years (OR: 3.24; 95% CI: 1.34-7.81; p = 0.009) and alcohol abuse (OR: 0.12; 95% CI: 0.03 to 0.55; p = 0.003). In our study, patients who had had previous treatment for tuberculosis, who were 45-64 years of age or who had no history of alcohol abuse were more likely to have MDR-TB.

Increasing antituberculosis drug resistance in the United Kingdom: analysis of National Surveillance Data

OBJECTIVE

To identify recent trends in, and factors associated with, resistance to antituberculosis drugs in England, Wales, and Northern Ireland.

DESIGN

Cohort of tuberculosis cases reported to the enhanced tuberculosis surveillance system matched to data on drug susceptibility and national strain typing data.

SETTING

England, Wales, and Northern Ireland 1998-2005.

MAIN OUTCOME MEASURES

Unadjusted and adjusted odds ratios for drug resistance and associated factors. Proportion of multidrug resistant tuberculosis cases clustered.

RESULTS

28 620 culture confirmed cases were available for analysis. The proportion of cases resistant to isoniazid increased from 5% to 7%. Rifampicin resistance increased from 1.0% to 1.2% and multidrug resistance from 0.8% to 0.9%. Ethambutol and pyrazinamide resistance remained stable at around 0.4% and 0.6%, respectively. Regression analyses showed a significant increase in isoniazid resistance outside London (odds ratio 1.04, 95% confidence interval 1.01 to 1.07, a year, associated with changes in age (0.98, 0.98 to 0.99, a year), place of birth (1.49, 1.16 to 1.92), and ethnicity (P<0.05). In London, the rise (1.05, 1.02 to 1.08, a year) was related mainly to an ongoing outbreak. Increases in rifampicin resistance (1.06, 1.01 to 1.11, a year) and multidrug resistance (1.06, 1.00 to 1.12, a year) were small. A fifth of patients with multidrug resistant tuberculosis in 2004-5 had indistinguishable strain types, and one case was identified as extensively drug resistant.

CONCLUSIONS

The rise in isoniazid resistance reflects increasing numbers of patients from sub-Saharan Africa and the Indian subcontinent, who might have acquired resistance abroad, and inadequate control of transmission in London. The observed increases highlight the need for early case detection, rapid testing of susceptibility to drugs, and improved treatment completion.

Increasing drug resistant tuberculosis in the UK

Control depends on a global perspective, not solely on local strategies

Tuberculosis: a radiologic review

Tuberculosis has shown a resurgence in nonendemic populations in recent years, a phenomenon that has been attributed to factors such as increased migration and the human immunodeficiency virus epidemic. Although the thorax is most frequently involved, tuberculosis may involve any of a number of organ systems (eg, the respiratory, cardiac, central nervous, musculoskeletal, gastrointestinal, and genitourinary systems), and timely diagnosis of the disease is paramount, since delayed treatment is associated with severe morbidity. Unfortunately, a history of infection with or exposure to tuberculosis may or may not be present, and evidence of active tuberculosis is present in less than 50% of cases. A negative tuberculin skin test does not in itself exclude infection. Furthermore, the clinical and radiologic features of tuberculosis may mimic those of many other diseases. Therefore, although in many cases biopsy or culture specimens are required to make the definitive diagnosis, it is imperative that radiologists and clinicians understand the typical distribution, patterns, and imaging manifestations of tuberculosis.

Antimicrobial susceptibility testing of Mycobacterium tuberculosis (EUCAST document E.DEF 8.1)--report of the Subcommittee on Antimicrobial Susceptibility Testing of Mycobacterium tuberculosis of the European Committee for Antimicrobial Susceptibility Testing (EUCAST) of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID)

This review describes the methods available for drug susceptibility testing of Mycobacterium tuberculosis. The methods have been developed over several decades and are restricted to specialised centres in most European countries, as they are technically demanding, require appropriate isolation facilities and can be difficult to interpret. The absolute concentration, resistance ratio and proportion methods can all give accurate results, provided that they are carefully quality-controlled and standardised. Automated rapid culture and molecular methods have been evaluated at large reference centres and in multicentre collaborations, and perform well for testing susceptibility to most first- and second-line anti-tuberculosis drugs. Accuracy is more important than rapid testing, and this is most reliably achieved if drug susceptibility tests are done in a small number of well-equipped, experienced laboratories that participate and perform well in an international drug susceptibility testing quality assessment scheme. The WHO Supranational Laboratory Quality Control Network offers a global scheme that assesses the ability of participating laboratories to identify isoniazid, rifampicin, ethambutol and streptomycin resistance. Second-line drug resistance testing is currently being standardised, and such testing should only be performed at the national reference laboratories in western and central European countries because of the relatively small number of cases and the concomitant difficulty of maintaining testing proficiency in multiple centres performing small numbers of tests. There is a need to expand international external quality assessment to include second-line drug susceptibility testing.

Drug resistance rates of Mycobacterium tuberculosis at a private referral center in Korea

The goals of this study were to identify first-line drug resistance in new and previously treated tuberculosis (TB) cases and to determine risk factors for multidrug resistant TB (MDR-TB) at a private referral center in Korea. All patients with culture confirmed pulmonary TB over a 2-yr period between July 2002 and June 2004 were prospectively included in this study. In total, 637 patients were included; 512 (80.4%) were new cases, and 125 (19.6%) were previously treated cases. Resistance to at least one first-line drug was identified in 11.7% of new cases and 41.6% of previously treated cases. MDR-TB was detected in 3.9% of new cases and 27.2% of previously treated cases. The proportion of extensively drug-resistant TB among MDR-TB patients was 16.7% (9/54). Factors associated with MDR-TB included age under 45 yr, previous TB treatment, and the presence of cavitation on chest radiography. Rates of first-line drug resistance are high, particularly in previously treated patients, in the private sector in Korea. This underscores the need for an improved control program, coupled with early diagnosis of MDR-TB, to reduce the spread and development of resistance.

Key issues in multidrug-resistant tuberculosis

Tuberculosis is responsible for 2 million deaths worldwide and 8 million new cases are reported globally every year. Multidrug-resistant tuberculosis (MDR-TB) is an emerging and difficult public health problem worldwide. In the presence of resistance to key first-line antituberculous agents, treatment with less effective and more toxic second-line agents must be instituted. Consequently, patients remain infectious for a longer period and require prolonged courses of treatment. There may be a role for surgery in selected cases. Care must be taken in terms of isolation procedure and infection control in MDR-TB. Although the diagnosis is made microbiologically, there are certain factors that predispose to the emergence of MDR-TB, notably a history of previous treatment for TB, particularly if that treatment was inadequate or incomplete. Prescription errors made by physicians also contribute, such as adding a single drug to a failing anti-TB regimen. The use of DNA amplification techniques, for example polymerase chain reaction has resulted in the rapid diagnosis of MDR-TB compared with traditional solid culture media. Treatment of MDR-TB usually involves five drugs to which microbiologically, the organism has been shown to demonstrate susceptibility, and one of these drugs should be an injectable agent. There is a need for greater research into developing more effective antituberculous medications and immunotherapy may play an adjunctive role in future management.

Antibody based target tailored antimicrobial chemotherapy - a new approach

Ever since antimicrobial therapy was introduced, two phenomenons have been observed: drug resistance and host toxicity. Mutation(s) in microbes leads to the earlier, while off target effects of therapy cause the latter. Neither of these problems have yet to be resolved. All Microbes express specific antigens, against which monoclonal antibodies can be generated ex vivo. If these specific antibodies are conjugated with antimicrobial drugs, it would lead to an increase in the specificity of antimicrobial chemotherapy agents. Moreover, the antibodies also work as anti-infective agents by directing the human immune response to the pathogen. As a result, antibody conjugated antimicrobial chemotherapy may have lower side effects, higher potency and efficacy.

Risk factors for multidrug resistant tuberculosis in Europe: a systematic review

BACKGROUND

The resurgence of tuberculosis (TB) in western countries has been attributed to the HIV epidemic, immigration, and drug resistance. Multidrug resistant tuberculosis (MDR-TB) is caused by the transmission of multidrug resistant Mycobacterium tuberculosis strains in new cases, or by the selection of single drug resistant strains induced by previous treatment. The aim of this report is to determine risk factors for MDR-TB in Europe.

METHODS

A systematic review was conducted of published reports of risk factors associated with MDR-TB in Europe. Meta-analysis, meta-regression, and sub-grouping were used to pool risk estimates of MDR-TB and to analyse associations with age, sex, immigrant status, HIV status, occurrence year, study design, and area of Europe.

RESULTS

Twenty nine papers were eligible for the review from 123 identified in the search. The pooled risk of MDR-TB was 10.23 times higher in previously treated than in never treated cases, with wide heterogeneity between studies. Study design and geographical area were associated with MDR-TB risk estimates in previously treated patients; the risk estimates were higher in cohort studies carried out in western Europe (RR 12.63; 95% CI 8.20 to 19.45) than in eastern Europe (RR 8.53; 95% CI 6.57 to 11.06). National estimates were possible for six countries. MDR-TB cases were more likely to be foreign born (odds ratio (OR) 2.46; 95% CI 1.86 to 3.24), younger than 65 years (OR 2.53; 95% CI 1.74 to 4.83), male (OR 1.38; 95% CI 1.16 to 1.65), and HIV positive (OR 3.52; 95% CI 2.48 to 5.01).

CONCLUSIONS

Previous treatment was the strongest determinant of MDR-TB in Europe. Detailed study of the reasons for inadequate treatment could improve control strategies. The risk of MDR-TB in foreign born people needs to be re-evaluated, taking into account any previous treatment.

Nosocomial pulmonary infections in HIV-positive patients

PURPOSE OF REVIEW

Nosocomial infections (NI) constitute a significant public health problem and contribute to prolonged hospitalization, additional healthcare costs, and excess morbidity and mortality. Immunocompromised patients, including HIV-infected individuals, are at increased risk for NI, and 15-18.3% of them are represented by lower respiratory tract infections. Nosocomial pulmonary infections (NPI) appear to be more common in patients with acquired immunodeficiency syndrome (AIDS), as a result of the degree of immunosuppression, prior use of antibiotics, and exposure to invasive procedures.

RECENT FINDINGS

This article reviews the epidemiologic and clinical evidences and reports on the occurrence of NPI in HIV-infected inpatients.

SUMMARY

Although underestimated, NI occur commonly in HIV-infected patients, and among them nosocomial pneumonia, including tuberculosis and bacterial pneumonia, are associated with significant morbidity and mortality. The improvement of antiretroviral therapeutic options in developed countries has resulted in a decreased hospitalization rate of HIV-infected individuals. Healthcare delivery in the in- and outpatient setting represents a potential for infections, including lower respiratory tract ones, according to the degree of immunosuppression and the intensity of invasive procedures. To minimize the risk of acquisition of healthcare associated low respiratory tract infections, adherence of healthcare workers to common infection practices, specific respiratory precautions, and early identification of persons who have tuberculosis or are at high risk for active tuberculosis, should be strengthened.

Rates of drug resistance and risk factor analysis in civilian and prison patients with tuberculosis in Samara Region, Russia

BACKGROUND

Tuberculosis (TB) and HIV rates continue to escalate in Russia, but true rates for drug resistance, especially multidrug resistant tuberculosis (MDR TB), are unknown. A study was conducted with the aims of identifying first line drug resistance, both in the civilian and prison sectors, for new and previously treated cases; and risk factors for the development of drug resistance.

METHODS

A cross sectional survey was undertaken of 600 patients (309 civilians, 291 prisoners) with bacteriologically confirmed pulmonary TB over a 1 year period during 2001-2 in Samara Oblast, Russia.

RESULTS

The prevalence of isoniazid, rifampicin, streptomycin, ethambutol and pyrazinamide resistance in new TB cases (civilian and prison patients) was 38.0%, 25.2%, 34.6%, 14.7%, and 7.2%, respectively. The prevalence of MDR TB was 22.7%, 19.8%, and 37.3% in all new cases, new civilian cases, and new prison cases, respectively, with an overall prevalence of 45.5% and 55.3% in previously treated cases. Factors associated with resistance included previous TB treatment for more than 4 weeks, smoking (for isoniazid resistance), the presence of cavitations on the chest radiograph, and imprisonment. HIV was not associated with resistance in all patients. The rates of resistance were significantly higher in prisoners, with rate ratios (RR) of 1.9 (95% CI 1.1 to 3.2) for MDR TB, 1.9 (95% CI 1.1 to 3.2) for rifampicin, and 1.6 (95% CI 1.0 to 2.6) for isoniazid.

CONCLUSIONS

Rates of first line drug resistance are high, particularly in prisoners and previously treated cases. TB control programmes should initially focus on standardised treatment to maximise cure, combined with measures to reduce institutional TB spread (particularly in prisons) coupled with early diagnosis of MDR TB to reduce the spread and development of resistance.

The exercise of public health powers in an era of human rights: the particular problems of tuberculosis

Public health legislation provides powers of removal to hospital and detention in circumstances where a patient with active, infectious tuberculosis (TB) is unwilling to comply with the recommended treatment programme. However, these public health powers were drafted at a time of very different scientific understandings of the epidemiology of disease, and at a time of a very different appreciation of the balance between State paternalism and individual rights. The re-emergence of TB as a serious threat to public health in Britain, and the increasing incidence of multi-drug-resistant TB raises concerns about public health approaches to non-compliant patients. The Human Rights Act (1998) introduces into English domestic law, protections against interference with individual rights by public authorities. The Human Rights Act not only provides a new basis of challenge of the exercise of powers by a public body, but has also had implications for the development of traditional means of challenge such as judicial review and litigation for damages. The consequence is that NHS authorities and local authorities are now more vulnerable to challenge in the exercise of public health powers. Health bodies should explore all possible alternatives to detention of a patient suffering from TB. It is to be hoped that the heralded reform to public health legislation is undertaken as a priority.

The global situation of MDR-TB

Drug-resistant tuberculosis has been reported since the early days of the introduction of chemotherapy. However, most of the evidence was limited to developed countries. In 1992, the Third World Congress on Tuberculosis concluded that there was little recent information on the global magnitude of multidrug-resistant tuberculosis (MDR-TB), defined as resistance to at least isoniazid and rifampicin. Through the WHO/IUATLD Global Project on Drug-Resistance Surveillance launched in 1994, a large number of reliable and accurate data have allowed us to understand the magnitude of the problem of MDR-TB. The data available suggest that globally MDR-TB is not a problem (median = 1% in 64 countries/geographical sites surveyed) of the same magnitude as that of drug-susceptible tuberculosis. However, MDR-TB is at critical levels in specific regions of the world. Hot spots for MDR-TB include Estonia, Latvia, the Oblasts of Ivanovo and Tomsk in Russia, and the provinces of Henan and Zhejiang Provinces in China. Trends confirm that MDR-TB is limited to local epidemics but the evidence is not yet irrefutable, as many countries have only provided short-term data. Two-thirds of the world's countries and, more importantly, half of the 22 tuberculosis high-burden countries, have not yet provided data. Mathematical modelling suggests that 3.2% (or 273,000) of the world's estimated new tuberculosis cases (95% confidence intervals: 185,000 and 414,000) were MDR-TB in 2000. Adoption of DOTS to prevent the generation of resistant strains and careful introduction of second-line drugs to treat patients with MDR are the top priorities for proper control/containment of MDR-TB.

Widespread pyrazinamide-resistant Mycobacterium tuberculosis family in a low-incidence setting

An unusually high prevalence of pyrazinamide (PZA) monoresistance in Mycobacterium tuberculosis has been observed in Quebec. In the absence of a recognized outbreak, we hypothesized that these isolates most likely represented reactivation of an old endemic strain in this low-incidence area. A case-control study of 77 PZA-resistant isolates with a specific Quebec mutation and 253 PZA-susceptible control M. tuberculosis isolates was undertaken. By molecular analysis, all 77 case isolates shared a unique mutation profile in the pncA gene which was not present in control isolates. While control isolates manifested diverse IS6110 restriction fragment length polymorphism (RFLP) patterns, spoligotypes, and major genetic groups, case isolates had similar but nonidentical IS6110 RFLP patterns, had common spoligotypes, and were confined to one major genetic group, suggesting a common clonal ancestor. By epidemiologic and geographic analyses, however, there were no significant differences between the cases and the controls. We conclude that a clonally related family of PZA-monoresistant M. tuberculosis isolates in Quebec represents historic rather than recent transmission.

Evaluation and utilization as a public health tool of a national molecular epidemiological tuberculosis outbreak database within the United Kingdom from 1997 to 2001

The aim of this study was to develop a national model and analyze the value of a molecular epidemiological Mycobacterium tuberculosis DNA fingerprint-outbreak database. Incidents were investigated by the United Kingdom PHLS Mycobacterium Reference Unit (MRU) from June 1997 to December 2001, inclusive. A total of 124 incidents involving 972 tuberculosis cases, including 520 patient cultures from referred incidents and 452 patient cultures related to two population studies, were examined by using restriction fragment length polymorphism IS6110 fingerprinting and rapid epidemiological typing. Investigations were divided into the following three categories, reflecting different operational strategies: retrospective passive analysis, retrospective active analysis, and retrospective prospective analysis. The majority of incidents were in the retrospective passive analysis category, i.e., the individual submitting isolates has a suspicion they may be linked. Outbreaks were examined in schools, hospitals, farms, prisons, and public houses, and laboratory cross-contamination events and unusual clinical presentations were investigated. Retrospective active analysis involved a major outbreak centered on a high school. Contact tracing of a teenager with smear-positive pulmonary tuberculosis matched 14 individuals, including members of his class, and another 60 cases were identified in schools clinically and radiologically and by skin testing. Retrospective prospective analysis involved an outbreak of 94 isoniazid-resistant tuberculosis cases in London, United Kingdom, that began after cases were identified at one hospital in January 2000. Contact tracing and comparison with MRU databases indicated that the earliest matched case had occurred in 1995. Subsequently, the MRU changed to an active prospective analysis targeting linked isoniazid-monoresistant isolates for follow up. The patients were multiethnic, born mainly in the United Kingdom, and included professionals, individuals from the music industry, intravenous drug abusers, and prisoners.

A national study of clinical and laboratory factors affecting the survival of patients with multiple drug resistant tuberculosis in the UK

BACKGROUND

This study aimed to describe the clinical, microbiological, molecular epidemiology and treatment of multidrug resistant tuberculosis (MDRTB) cases in the UK and to determine factors associated with survival.

METHODS

Ninety MDRTB cases were identified from 1 January 1996 to 30 June 1997; 69 were DNA fingerprinted. Date of diagnosis was determined and data were collated on key demographic factors, clinical, radiological and treatment details. Variables associated with survival were included in a Cox proportional hazards model.

RESULTS

Most of the patients (72.4%) were male, born outside the UK (57.1%), were sputum smear positive (82.2%), and had entered the UK more than 5 years previously (61.9%). Thirty eight of 78 cases (48.7%) had prior TB. Sufficient data on 82 patients were available for survival analysis; 20/27 (74.1%) known to be dead at the end of the observation period had died of tuberculosis. Median survival time overall was 1379 days (95% CI 1336 to 2515) or 3.78 (95% CI 3.66 to 6.89) years (858 days (95% CI 530 to 2515) in immunocompromised individuals (n=32) and 1554 (95% CI 1336 to 2066) days in immunocompetent cases (n=48)). Median survival in patients treated with three drugs to which the bacterium was susceptible on in vitro testing (n=62) was 2066 days (95% CI 1336 to 2515) or 5.66 years, whereas in those not so treated (n=13) survival was 599 days (95% CI 190 to 969) or 1.64 years.

CONCLUSIONS

Immunocompromised status, failure to culture the bacterium in 30 days or to apply appropriate three drug treatment, and age were significant factors in mortality. An immunocompromised patient was nearly nine times more likely to die, while application of appropriate treatment reduced the risk (risk ratio 0.06). Increasing age was associated with increasing risk of death (risk ratio 2.079; 95% CI 1.269 to 3.402)-that is, for every 10 year increase in age the risk almost doubled. Overall survival was lower than that reported in previous studies.