Rifampicin and clarithromycin (extended release) versus rifampicin and streptomycin for limited Buruli ulcer lesions: a randomised, open-label, non-inferiority phase 3 trial

BACKGROUND

Buruli ulcer is a neglected tropical disease caused by Mycobacterium ulcerans infection that damages the skin and subcutis. It is most prevalent in western and central Africa and Australia. Standard antimicrobial treatment with oral rifampicin 10 mg/kg plus intramuscular streptomycin 15 mg/kg once daily for 8 weeks (RS8) is highly effective, but streptomycin injections are painful and potentially harmful. We aimed to compare the efficacy and tolerability of fully oral rifampicin 10 mg/kg plus clarithromycin 15 mg/kg extended release once daily for 8 weeks (RC8) with that of RS8 for treatment of early Buruli ulcer lesions.

METHODS

We did an open-label, non-inferiority, randomised (1:1 with blocks of six), multicentre, phase 3 clinical trial comparing fully oral RC8 with RS8 in patients with early, limited Buruli ulcer lesions. There were four trial sites in hospitals in Ghana (Agogo, Tepa, Nkawie, Dunkwa) and one in Benin (Pobè). Participants were included if they were aged 5 years or older and had typical Buruli ulcer with no more than one lesion (caterories I and II) no larger than 10 cm in diameter. The trial was open label, and neither the investigators who took measurements of the lesions nor the attending doctors were masked to treatment assignment. The primary clinical endpoint was lesion healing (ie, full epithelialisation or stable scar) without recurrence at 52 weeks after start of antimicrobial therapy. The primary endpoint and safety were assessed in the intention-to-treat population. A sample size of 332 participants was calculated to detect inferiority of RC8 by a margin of 12%. This study was registered with ClinicalTrials.gov, NCT01659437.

FINDINGS

Between Jan 1, 2013, and Dec 31, 2017, participants were recruited to the trial. We stopped recruitment after 310 participants. Median age of participants was 14 years (IQR 10-29) and 153 (52%) were female. 297 patients had PCR-confirmed Buruli ulcer; 151 (51%) were assigned to RS8 treatment, and 146 (49%) received oral RC8 treatment. In the RS8 group, lesions healed in 144 (95%, 95% CI 91 to 98) of 151 patients, whereas lesions healed in 140 (96%, 91 to 99) of 146 patients in the RC8 group. The difference in proportion, -0·5% (-5·2 to 4·2), was not significantly greater than zero (p=0·59), showing that RC8 treatment is non-inferior to RS8 treatment for lesion healing at 52 weeks. Treatment-related adverse events were recorded in 20 (13%) patients receiving RS8 and in nine (7%) patients receiving RC8. Most adverse events were grade 1-2, but one (1%) patient receiving RS8 developed serious ototoxicity and ended treatment after 6 weeks. No patients needed surgical resection. Four patients (two in each study group) had skin grafts.

INTERPRETATION

Fully oral RC8 regimen was non-inferior to RS8 for treatment of early, limited Buruli ulcer and was associated with fewer adverse events. Therefore, we propose that fully oral RC8 should be the preferred therapy for early, limited lesions of Buruli ulcer.

FUNDING

WHO with additional support from MAP International, American Leprosy Missions, Fondation Raoul Follereau France, Buruli ulcer Groningen Foundation, Sanofi-Pasteur, and BuruliVac.

Mutations in pepQ Confer Low-Level Resistance to Bedaquiline and Clofazimine in Mycobacterium tuberculosis

The novel ATP synthase inhibitor bedaquiline recently received accelerated approval for treatment of multidrug-resistant tuberculosis and is currently being studied as a component of novel treatment-shortening regimens for drug-susceptible and multidrug-resistant tuberculosis. In a limited number of bedaquiline-treated patients reported to date, ≥4-fold upward shifts in bedaquiline MIC during treatment have been attributed to non-target-based mutations in Rv0678 that putatively increase bedaquiline efflux through the MmpS5-MmpL5 pump. These mutations also confer low-level clofazimine resistance, presumably by a similar mechanism. Here, we describe a new non-target-based determinant of low-level bedaquiline and clofazimine cross-resistance in Mycobacterium tuberculosis: loss-of-function mutations in pepQ (Rv2535c), which corresponds to a putative Xaa-Pro aminopeptidase. pepQ mutants were selected in mice by treatment with clinically relevant doses of bedaquiline, with or without clofazimine, and were shown to have bedaquiline and clofazimine MICs 4 times higher than those for the parental H37Rv strain. Coincubation with efflux inhibitors verapamil and reserpine lowered bedaquiline MICs against both mutant and parent strains to a level below the MIC against H37Rv in the absence of efflux pump inhibitors. However, quantitative PCR (qPCR) revealed no significant differences in expression of Rv0678, mmpS5, or mmpL5 between mutant and parent strains. Complementation of a pepQ mutant with the wild-type gene restored susceptibility, indicating that loss of PepQ function is sufficient for reduced susceptibility both in vitro and in mice. Although the mechanism by which mutations in pepQ confer bedaquiline and clofazimine cross-resistance remains unclear, these results may have clinical implications and warrant further evaluation of clinical isolates with reduced susceptibility to either drug for mutations in this gene.

Genomic and functional analyses of Mycobacterium tuberculosis strains implicate ald in D-cycloserine resistance

A more complete understanding of the genetic basis of drug resistance in Mycobacterium tuberculosis is critical for prompt diagnosis and optimal treatment, particularly for toxic second-line drugs such as D-cycloserine. Here we used the whole-genome sequences from 498 strains of M. tuberculosis to identify new resistance-conferring genotypes. By combining association and correlated evolution tests with strategies for amplifying signal from rare variants, we found that loss-of-function mutations in ald (Rv2780), encoding L-alanine dehydrogenase, were associated with unexplained drug resistance. Convergent evolution of this loss of function was observed exclusively among multidrug-resistant strains. Drug susceptibility testing established that ald loss of function conferred resistance to D-cycloserine, and susceptibility to the drug was partially restored by complementation of ald. Clinical strains with mutations in ald and alr exhibited increased resistance to D-cycloserine when cultured in vitro. Incorporation of D-cycloserine resistance in novel molecular diagnostics could allow for targeted use of this toxic drug among patients with susceptible infections.

Evolution of Extensively Drug-Resistant Tuberculosis over Four Decades: Whole Genome Sequencing and Dating Analysis of Mycobacterium tuberculosis Isolates from KwaZulu-Natal

BACKGROUND

The continued advance of antibiotic resistance threatens the treatment and control of many infectious diseases. This is exemplified by the largest global outbreak of extensively drug-resistant (XDR) tuberculosis (TB) identified in Tugela Ferry, KwaZulu-Natal, South Africa, in 2005 that continues today. It is unclear whether the emergence of XDR-TB in KwaZulu-Natal was due to recent inadequacies in TB control in conjunction with HIV or other factors. Understanding the origins of drug resistance in this fatal outbreak of XDR will inform the control and prevention of drug-resistant TB in other settings. In this study, we used whole genome sequencing and dating analysis to determine if XDR-TB had emerged recently or had ancient antecedents.

METHODS AND FINDINGS

We performed whole genome sequencing and drug susceptibility testing on 337 clinical isolates of Mycobacterium tuberculosis collected in KwaZulu-Natal from 2008 to 2013, in addition to three historical isolates, collected from patients in the same province and including an isolate from the 2005 Tugela Ferry XDR outbreak, a multidrug-resistant (MDR) isolate from 1994, and a pansusceptible isolate from 1995. We utilized an array of whole genome comparative techniques to assess the relatedness among strains, to establish the order of acquisition of drug resistance mutations, including the timing of acquisitions leading to XDR-TB in the LAM4 spoligotype, and to calculate the number of independent evolutionary emergences of MDR and XDR. Our sequencing and analysis revealed a 50-member clone of XDR M. tuberculosis that was highly related to the Tugela Ferry XDR outbreak strain. We estimated that mutations conferring isoniazid and streptomycin resistance in this clone were acquired 50 y prior to the Tugela Ferry outbreak (katG S315T [isoniazid]; gidB 130 bp deletion [streptomycin]; 1957 [95% highest posterior density (HPD): 1937-1971]), with the subsequent emergence of MDR and XDR occurring 20 y (rpoB L452P [rifampicin]; pncA 1 bp insertion [pyrazinamide]; 1984 [95% HPD: 1974-1992]) and 10 y (rpoB D435G [rifampicin]; rrs 1400 [kanamycin]; gyrA A90V [ofloxacin]; 1995 [95% HPD: 1988-1999]) prior to the outbreak, respectively. We observed frequent de novo evolution of MDR and XDR, with 56 and nine independent evolutionary events, respectively. Isoniazid resistance evolved before rifampicin resistance 46 times, whereas rifampicin resistance evolved prior to isoniazid only twice. We identified additional putative compensatory mutations to rifampicin in this dataset. One major limitation of this study is that the conclusions with respect to ordering and timing of acquisition of mutations may not represent universal patterns of drug resistance emergence in other areas of the globe.

CONCLUSIONS

In the first whole genome-based analysis of the emergence of drug resistance among clinical isolates of M. tuberculosis, we show that the ancestral precursor of the LAM4 XDR outbreak strain in Tugela Ferry gained mutations to first-line drugs at the beginning of the antibiotic era. Subsequent accumulation of stepwise resistance mutations, occurring over decades and prior to the explosion of HIV in this region, yielded MDR and XDR, permitting the emergence of compensatory mutations. Our results suggest that drug-resistant strains circulating today reflect not only vulnerabilities of current TB control efforts but also those that date back 50 y. In drug-resistant TB, isoniazid resistance was overwhelmingly the initial resistance mutation to be acquired, which would not be detected by current rapid molecular diagnostics employed in South Africa that assess only rifampicin resistance.

Treatment of tuberculosis and optimal dosing schedules

Intermittent tuberculosis treatment regimens have been developed to facilitate treatment supervision. Their efficacy has been substantiated by clinical trials and tuberculosis control programmes, notwithstanding the lack of head-to-head comparison between daily and intermittent regimens. Recently, there has been opposing evidence from observational studies, pharmacokinetic-pharmacodynamic studies and animal models that intermittent treatment increases the risk of relapse, treatment failure or acquired rifamycin resistance, especially among HIV-infected patients. Systematic reviews have been conflicting. PubMed, Ovid MEDLINE and EMBASE were systematically searched for publications in English to evaluate the evidence about dosing schedules and treatment efficacy. Levels of evidence and grades of recommendation were assigned largely according to clinical evidence with reference to the Scottish Intercollegiate Guidelines Network guideline development handbook. A total of 32 articles were included after excluding 331 ineligible articles, 42 non-analytical studies, 22 narrative reviews or expert opinions and 44 articles embedded in systematic reviews. These included 9 systematic reviews, 8 controlled studies, 9 pharmacokinetic-pharmacodynamic studies, 5 mouse studies and 1 article about guinea pig experiments. Findings suggest high levels of evidence for using daily dosing schedules, especially during the initial phase in the presence of cavitation, isoniazid resistance and advanced HIV co-infection, to reduce the risk of treatment failure, recurrence and acquired drug resistance including acquired rifamycin resistance. This review justifies the use of daily schedules in standard tuberculosis treatment regimens (particularly in the initial phase), corroborates prevailing understanding of pharmacokinetics-pharmacodynamics and mycobacterial persisters, and supports exploration of rifapentine-containing regimens in higher dosages and frequency.

Methionine aminopeptidases from Mycobacterium tuberculosis as novel antimycobacterial targets

Methionine aminopeptidase (MetAP) is a metalloprotease that removes the N-terminal methionine during protein synthesis. To assess the importance of the two MetAPs in Mycobacterium tuberculosis, we overexpressed and purified each of the MetAPs to near homogeneity and showed that both were active as MetAP enzymes in vitro. We screened a library of 175,000 compounds against MtMetAP1c and identified 2,3-dichloro-1,4-naphthoquinone class of compounds as inhibitors of both MtMetAPs. It was found that the MtMetAP inhibitors were active against replicating and aged nongrowing M. tuberculosis. Overexpression of either MtMetAP1a or MtMetAP1c in M. tuberculosis conferred resistance of bacterial cells to the inhibitors. Moreover, knockdown of MtMetAP1a, but not MtMetAP1c, resulted in decreased viability of M. tuberculosis. These results suggest that MtMetAP1a is a promising target for developing antituberculosis agents.

Benzothiazinones kill Mycobacterium tuberculosis by blocking arabinan synthesis

New drugs are required to counter the tuberculosis (TB) pandemic. Here, we describe the synthesis and characterization of 1,3-benzothiazin-4-ones (BTZs), a new class of antimycobacterial agents that kill Mycobacterium tuberculosis in vitro, ex vivo, and in mouse models of TB. Using genetics and biochemistry, we identified the enzyme decaprenylphosphoryl-beta-d-ribose 2'-epimerase as a major BTZ target. Inhibition of this enzymatic activity abolishes the formation of decaprenylphosphoryl arabinose, a key precursor that is required for the synthesis of the cell-wall arabinans, thus provoking cell lysis and bacterial death. The most advanced compound, BTZ043, is a candidate for inclusion in combination therapies for both drug-sensitive and extensively drug-resistant TB.

Murine model to study the invasion and survival of Mycobacterium tuberculosis in the central nervous system

BACKGROUND

Tuberculosis of the central nervous system (CNS) is a serious, often fatal disease primarily affecting young children. It develops after hematogenous dissemination and subsequent invasion of the CNS by Mycobacterium tuberculosis. The microbial determinants involved in CNS disease are poorly characterized.

METHODS

Hematogenously disseminated M. tuberculosis infection was simulated in BALB/c mice by intravenous challenge. Bacteria were recovered using standard culture techniques. Host immune response to M. tuberculosis infection was assessed by histopathological and cytokine profile analysis. By means of a pooled infection with genotypically defined M. tuberculosis mutants, bacterial genes required for invasion or survival were determined in the CNS and lung tissue.

RESULTS

M. tuberculosis were detected in whole mouse brains as early as 1 day after intravenous infection and at all time points assessed thereafter. No significant immune response was elicited in the infected brain tissue, compared with extensive inflammation in the infected lung tissue at the same time point. We identified mutants for 5 M. tuberculosis genes (Rv0311, Rv0805, Rv0931c, Rv0986, and MT3280) with CNS-specific phenotypes, absent in lung tissue.

CONCLUSIONS

We have identified CNS-specific M. tuberculosis genes involved in the pathogenesis of tuberculosis. Further characterization of these genes will help in understanding the microbial pathogenesis of CNS tuberculosis.

Promising clinical efficacy of streptomycin-rifampin combination for treatment of buruli ulcer (Mycobacterium ulcerans disease)

According to recommendations of the 6th WHO Advisory Committee on Buruli ulcer, directly observed treatment with the combination of rifampin and streptomycin, administered daily for 8 weeks, was recommended to 310 patients diagnosed with Buruli ulcer in Pobè, Bénin. Among the 224 (72%) eligible patients for whom treatment was initiated, 215 (96%) were categorized as treatment successes, and 9, including 1 death and 8 losses to follow-up, were treatment failures. Of the 215 successfully treated patients, 102 (47%) were treated exclusively with antibiotics and 113 (53%) were treated with antibiotics plus surgical excision and skin grafting. The size of lesions at treatment initiation was the major factor associated with surgical intervention: 73% of patients with lesions of >15 cm in diameter underwent surgery, whereas only 17% of patients with lesions of <5 cm had surgery. No patient discontinued therapy for side effects from the antibiotic treatment. One year after stopping treatment, 208 of the 215 patients were actively retrieved to assess the long-term therapeutic results: 3 (1.44%) of the 208 retrieved patients had recurrence of Mycobacterium ulcerans disease, 2 among the 107 patients treated only with antibiotics and 1 among the 108 patients treated with antibiotics plus surgery. We conclude that the WHO-recommended streptomycin-rifampin combination is highly efficacious for treating M. ulcerans disease. Chemotherapy alone was successful in achieving cure in 47% of cases and was particularly effective against ulcers of less than 5 cm in diameter.

Accelerated detection of Mycobacterium tuberculosis genes essential for bacterial survival in guinea pigs, compared with mice

BACKGROUND

Mouse and guinea pig models have been used to identify Mycobacterium tuberculosis mutants attenuated for survival. However, unlike mice, M. tuberculosis-infected guinea pigs form caseating granulomas, which may simulate human disease more closely.

METHODS

We used designer arrays for defined mutant analysis, a high-throughput subtractive competition assay, for genotypically defined M. tuberculosis mutants and compared the survival of the same mutant pools in guinea pig and mouse aerosol models. Selected mutants found to be attenuated in either aerosol model were also analyzed in the mouse hollow-fiber model.

RESULTS

M. tuberculosis mutants representing 74 genes were tested. Eighteen M. tuberculosis mutants were attenuated for survival in either aerosol model, with 70% of selected mutants also attenuated in the mouse hollow-fiber model. The majority of attenuated mutants in the mouse aerosol model were detected only after 90 days of infection. There was a high degree of concordance between the genes identified by the 2 aerosol models, with detection being significantly earlier in the guinea pig (P<.0003).

CONCLUSIONS

We identified M. tuberculosis genes required for survival in mammalian lungs. The majority of mouse late-stage survival mutants were detected significantly earlier in the guinea pig, which suggests that differences in tuberculosis-induced lung pathologic changes may account for this accelerated detection.

Sentinel-site surveillance of Mycobacterium avium complex pulmonary disease

The incidence of Mycobacterium avium complex (MAC) pulmonary disease in HIV-negative patients was studied prospectively from January 1, 2000 to December 31, 2002 through 32 sentinel sites distributed all over France. Among the 275 patients who yielded MAC isolates from respiratory clinical specimens, 101 (36.7%) met the bacteriological, radiographical and clinical criteria established by the American Thoracic Society for nontuberculous mycobacterial respiratory disease. Of these 101 patients, 81 had underlying lung disease, mainly previous tuberculosis, bronchectasis or chronic obstructive pulmonary disease. Among the 20 patients with no underlying lung disease, 12 had a predisposing factor such as leukaemia or immunosuppressive treatment and eight had no predisposing factor. All patients with MAC respiratory disease had clinical symptoms, commonly cough and fatigue, and 52 (51.5%) were sputum smear positive for acid-fast bacillus. The ratio of patients with Mycobacterium avium complex pulmonary disease to patients with pulmonary tuberculosis in France was estimated to be 3% and the incidence of Mycobacterium avium complex pulmonary disease in France was 0.2 per 100,000 inhabitants.

Efficacy of the combination rifampin-streptomycin in preventing growth of Mycobacterium ulcerans in early lesions of Buruli ulcer in humans

Mycobacterium ulcerans disease is common in some humid tropical areas, particularly in parts of West Africa, and current management is by surgical excision of skin lesions ranging from early nodules to extensive ulcers (Buruli ulcer). Antibiotic therapy would be more accessible to patients in areas of Buruli ulcer endemicity. We report a study of the efficacy of antibiotics in converting early lesions (nodules and plaques) from culture positive to culture negative. Lesions were excised either immediately or after treatment with rifampin orally at 10 mg/kg of body weight and streptomycin intramuscularly at 15 mg/kg of body weight daily for 2, 4, 8, or 12 weeks and examined by quantitative bacterial culture, PCR, and histopathology for M. ulcerans. Lesions were measured during treatment. Five lesions excised without antibiotic treatment and five lesions treated with antibiotics for 2 weeks were culture positive, whereas three lesions treated for 4 weeks, five treated for 8 weeks, and three treated for 12 weeks were culture negative. No lesions became enlarged during antibiotic treatment, and most became smaller. Treatment with rifampin and streptomycin for 4 weeks or more inhibited growth of M. ulcerans in human tissue, and it provides a basis for proceeding to a trial of antibiotic therapy as an alternative to surgery for early M. ulcerans disease.

Bactericidal activity of the nitroimidazopyran PA-824 in a murine model of tuberculosis

The nitroimidazopyran PA-824 has potent in vitro activity against Mycobacterium tuberculosis, a narrow spectrum of activity limited primarily to the M. tuberculosis complex, and no demonstrable cross-resistance to a variety of antituberculosis drugs. In a series of experiments, we sequentially characterized the activity of PA-824 in an experimental murine model of tuberculosis. The minimal effective dose was 12.5 mg/kg of body weight/day. The minimal bactericidal dose (MBD) was 100 mg/kg/day. When PA-824 was used as monotherapy at the MBD, it exhibited promising bactericidal activity during the initial intensive phase of therapy that was similar to that of the equipotent dose of isoniazid in humans. In combination with isoniazid, PA-824 prevented the selection of isoniazid-resistant mutants. Perhaps more importantly, PA-824 also demonstrated potent activity during the continuation phase of therapy, during which it targeted bacilli that had persisted through an initial 2-month intensive phase of treatment with rifampin, isoniazid, and pyrazinamide. Together, these data strongly support further evaluation of PA-824 in combination with first- or second-line antituberculosis drugs to determine its potential contribution to the treatment of drug-susceptible or multidrug-resistant tuberculosis, respectively.

A Case-Control Study for Multidrug-Resistant Tuberculosis: Risk Factors in Four European Countries

The aim of this study was to detect risk factors for multidrug resistance in patients with pulmonary tuberculosis in four European Union countries: France, Germany, Italy, and Spain. A prospective epidemiological case control study was conducted, made up of patients with clinically diagnosed and microbiologically confirmed pulmonary tuberculosis in the four countries between 1997 and 2000. A total of 138 cases and 276 controls were studied. Considering the four countries as a whole, the most statistically significant risk factors were as follows: intravenous drug use (OR 4.68); asylum-seeker support (OR 2.55) as income factor; living in a nursing home (OR 2.05); previous tuberculosis (OR 2.03) with pulmonary location; prison (OR 2.02); known tuberculosis contacts (OR 2.01); immunosuppression other than human immunodeficiency virus (HIV) (OR 1.96); acquired immunodeficiency syndrome (AIDS) (OR 1.96); current tuberculosis with pulmonary location (OR 1.77); and health-care worker (OR 1.69). These risk factors will have to be taken into account in the European Union as a whole, as well as in each individual country, to establish a health policy of monitoring and control for these cases of multidrug resistance. Although rare, their seriousness makes them particularly important.

Dormancy phenotype displayed by extracellular Mycobacterium tuberculosis within artificial granulomas in mice

Mycobacterium tuberculosis residing within pulmonary granulomas and cavities represents an important reservoir of persistent organisms during human latent tuberculosis infection. We present a novel in vivo model of tuberculosis involving the encapsulation of bacilli in semidiffusible hollow fibers that are implanted subcutaneously into mice. Granulomatous lesions develop around these hollow fibers, and in this microenvironment, the organisms demonstrate an altered physiologic state characterized by stationary-state colony-forming unit counts and decreased metabolic activity. Moreover, these organisms show an antimicrobial susceptibility pattern similar to persistent bacilli in current models of tuberculosis chemotherapy in that they are more susceptible to the sterilizing drug, rifampin, than to the bactericidal drug isoniazid. We used this model of extracellular persistence within host granulomas to study both gene expression patterns and mutant survival patterns. Our results demonstrate induction of dosR (Rv3133c) and 20 other members of the DosR regulon believed to mediate the transition into dormancy, and that rel_Mtb is required for Mycobacterium tuberculosis survival during extracellular persistence within host granulomas. Interestingly, the dormancy phenotype of extracellular M. tuberculosis within host granulomas appears to be immune mediated and interferon-γ dependent.

Pharmacokinetic and pharmacodynamic issues in the treatment of mycobacterial infections

The therapy of mycobacterial infections is challenging for a number of reasons. Because mycobacteria are not susceptible to many classes of antibacterial agents, treatment typically requires the use of antimicrobial drugs that are not commonly used and may have small therapeutic windows. For many species, procedures for drug susceptibility testing and optimal treatment regimens have yet to be defined. Finally, because mycobacteria are generally slow to succumb to antimicrobial agents, therapy must be given with multiple drugs for prolonged periods of time, making it necessary to monitor for drug toxicity, drug interactions, and patient nonadherence. Better understanding of the pharmacokinetics and pharmacodynamics of antimycobacterial agents should improve the therapy of mycobacterial infections. Using current treatment strategies for tuberculosis and Mycobacterium avium complex infections as examples, this review highlights basic pharmacokinetic and pharmacodynamic principles and the rationale for combination chemotherapy that should also be applicable to other mycobacterial infections.

Drug resistance among failure and relapse cases of tuberculosis: is the standard re-treatment regimen adequate?

OBJECTIVE

To determine acquired drug resistance among failure and relapse cases after treatment of new smear-positive tuberculosis.

METHODS

A cohort of 2901 patients with new smear-positive tuberculosis was enrolled in Vietnam. Sputum samples were stored at enrolment. Upon failure or relapse, another sputum sample was collected. Both were cultured and underwent drug susceptibility testing and restriction fragment length polymorphism (RFLP) typing.

RESULTS

Of 40 failure cases, 17 had multidrug resistance (MDR) at enrolment. At failure, 15 of the 23 (65%) patients without primary MDR had acquired MDR. Of 39 relapse cases and 143 controls, none had primary MDR.

CONCLUSION

Primary drug resistance was a strong risk factor for failure and relapse and for acquiring further resistance. As 80% of failure cases had MDR, the standard re-treatment regimen appears inadequate for failure cases in this control programme with a very high cure rate among new cases.

A postgenomic method for predicting essential genes at subsaturation levels of mutagenesis: application to Mycobacterium tuberculosis

We describe a postgenomic in silico approach for identifying genes that are likely to be essential and estimate their proportion in haploid genomes. With the knowledge of all sites eligible for mutagenesis and an experimentally determined partial list of nonessential genes from genome mutagenesis, a Bayesian statistical method provides reasonable predictions of essential genes with a subsaturation level of random mutagenesis. For mutagenesis, a transposon such as Himar1 is suitable as it inserts randomly into TA sites. All of the possible insertion sites may be determined a priori from the genome sequence and with this information, data on experimentally hit TA sites may be used to predict the proportion of genes that cannot be mutated. As a model, we used the Mycobacterium tuberculosis genome. Using the Himar1 transposon, we created a genetically defined collection of 1,425 insertion mutants. Based on our Bayesian statistical analysis using Markov chain Monte Carlo and the observed frequencies of transposon insertions in all of the genes, we estimated that the M. tuberculosis genome contains 35% (95% confidence interval, 28%-41%) essential genes. This analysis further revealed seven functional groups with high probabilities of being enriched in essential genes. The PE-PGRS (Pro-Glu polymorphic GC-rich repetitive sequence) family of genes, which are unique to mycobacteria, the polyketide/nonribosomal peptide synthase family, and mycolic and fatty acid biosynthesis gene families were disproportionately enriched in essential genes. At subsaturation levels of mutagenesis with a random transposon such as Himar1, this approach permits a statistical prediction of both the proportion and identities of essential genes of sequenced genomes.

Impact of iron loading on the activity of isoniazid or ethambutol in the treatment of murine tuberculosis

OBJECTIVE

To assess the impact of iron loading on the activity of isoniazid and ethambutol in the treatment of murine tuberculosis.

DESIGN

Iron-loaded and iron-normal female Balb/C mice infected with 1.5 x 10(7) colony forming units of Mycobacterium tuberculosis were treated with either isoniazid or ethambutol for 28 days.

RESULTS

For both treatments, the outcome was impaired by the iron loading: bactericidal activity of isoniazid was partially but significantly reduced and ethambutol bactericidal activity was totally inhibited.

CONCLUSION

The treatment of tuberculosis in patients with iron loading should be longer than for normal patients or should contain an additional drug.

Bactericidal activity of rifampin-amikacin against Mycobacterium ulcerans in mice

To identify the most active curative treatment of Buruli ulcer, two regimens incorporating the use of rifampin (RIF) were compared with the use of RIF alone in a mouse footpad model of Mycobacterium ulcerans infection. Treatments began after footpad swelling from infection and continued for 12 weeks with five doses weekly of one of the following regimens: (i) 10 mg of RIF/kg alone; (ii) 10 mg of RIF/kg and 100 mg of amikacin (AMK)/kg; and (iii) 10 mg of RIF/kg, 100 mg of clarithromycin (CLR)/kg, and 50 mg of sparfloxacin (SPX)/kg. The activity of each regimen was assessed in terms of the reduction of the average lesion index and acid-fast bacillus (AFB) and CFU counts. All three regimens displayed various degrees of bactericidal activity against M. ulcerans. The ranking of bactericidal activity was found to be as follows: RIF-AMK > RIF-CLR-SPX > RIF. RIF-AMK was able to cure M. ulcerans-infected mice and prevent relapse 26 weeks after completion of treatment. To determine the impact of different rhythms of administration of RIF-AMK on the suppression of M.ulcerans growth, mice were given the RIF-AMK combination for 4 weeks but doses were administered either 5 days a week or twice or once weekly. After completion of treatment, the mice were kept under supervision for 30 additional weeks. M. ulcerans was considered to have grown in the footpad if swelling was visually observed and harvests contained more than 5 x 10(5) AFB per footpad. The proportion of mice in which growth of M. ulcerans occurred, irrespective of drug dosage, was compared with the control mice to determine the proportion of M. ulcerans killed. Each dosage of RIF-AMK was bactericidal for M. ulcerans (P < 0.001), but the effect was significantly stronger in mice treated 5 days per week. The promising results of RIF-AMK treatment in M. ulcerans-infected mice support the clinical trial that is currently in progress under World Health Organization auspices in Ghana.

Bactericidal activity of increasing daily and weekly doses of moxifloxacin in murine tuberculosis

Moxifloxacin (MXF) is a new 8-methoxyquinolone with potent activity against Mycobacterium tuberculosis and a half-life of 9 to 12 h in humans. Previous in vivo studies using daily doses of 100 mg/kg of body weight have demonstrated bactericidal activity comparable to that of isoniazid (INH) in a murine model of tuberculosis (TB). Recent pharmacokinetic data suggest that MXF may have been underadministered in these studies and that a 400-mg/kg dose in mice better approximates the area under the concentration-time curve obtained in humans after a 400-mg oral dose. Therefore, the bactericidal activity of MXF in doses up to 400 mg/kg given daily or weekly for 28 days was assessed in mice infected intravenously with 5 x 10(6) CFU of M. tuberculosis. INH was used as a positive control. After 3 days of daily therapy, the CFU counts from splenic homogenates for mice treated with MXF in doses of 100 to 400 mg/kg/day were lower than those from pretreatment controls. No significant differences in CFU counts were seen when mice receiving INH or MXF at 50 mg/kg/day were compared to pretreatment controls. After 28 days of therapy, dose-dependent reductions in CFU counts in splenic homogenates were seen for daily MXF therapy. The maximum bactericidal effect was seen with daily doses of 400 mg/kg, which resulted in a reduction in CFU counts of 1 log(10) greater than that with INH treatment, although the difference was not statistically significant. CFU counts from lung homogenates after 28 days of therapy were significantly lower in all treatment groups than in untreated controls. The weekly administration of MXF in doses ranging from 50 to 400 mg/kg resulted in no significant bactericidal activity. Mice receiving daily MXF doses of 200 and 400 mg/kg/day failed to gain weight and appeared ill after 28 days of therapy, findings suggestive of drug toxicity. In conclusion, MXF has dose-dependent bactericidal activity against M. tuberculosis in the mouse when given in doses up to 400 mg/kg, where its pharmacokinetic profile better approximates that of standard human dosages. Combination regimens which take advantage of the enhanced pharmacodynamic profile of MXF at these doses have the potential to shorten the course of antituberculous therapy or allow more intermittent (i.e., once-weekly) therapy and should be evaluated in the mouse model of TB.

Effectiveness of once-weekly rifapentine and moxifloxacin regimens against Mycobacterium tuberculosis in mice

Mice infected with 1.6 x 10(7) CFU of Mycobacterium tuberculosis were treated 14 days later for 6 months with a regimen of once-weekly 10 mg of rifapentine and 75 mg of isoniazid per kg of body weight supplemented with either 150 mg of streptomycin per kg or 100 mg of moxifloxacin per kg during either both the 2-week daily initial and once-weekly continuation phases or only in the daily 2-week initial phase. On completion of treatment, all lung cultures were negative, except for three mice, each with a single colony: two whose rifapentine-isoniazid regimen was supplemented with streptomycin during the whole course of therapy and one whose rifapentine-isoniazid regimen had no initial daily phase, but was supplemented with streptomycin and moxifloxacin during the whole course of therapy. After 3 months of follow-up, positive lung cultures were obtained from 61 and 56% of mice supplemented with streptomycin during either the full course of therapy or only the daily 2-week initial phase, respectively, and 15 and 50% of mice supplemented with moxifloxacin during either the full course of therapy or only the daily 2-week initial phase, respectively. These results suggest that moxifloxacin has sterilizing activity against M. tuberculosis.

Efficacies of clarithromycin regimens against Mycobacterium xenopi in mice

Mice were infected intravenously with 3.5 x 10(7) CFU of Mycobacterium xenopi and treated with various clarithromycin-containing regimens or left untreated for 4 weeks. All nine of the clarithromycin-containing regimens reduced the CFU counts to the levels below the pretreatment values, indicating that these regimens had a bactericidal effect on M. xenopi in mice. The rifampin-isoniazid-ethambutol regimen was significantly less bactericidal than clarithromycin alone or clarithromycin-containing combined regimens.

Activities of new macrolides and fluoroquinolones against Mycobacterium ulcerans infection in mice

Mice infected in the left hind footpad with 5 log(10) acid-fast bacilli of Mycobacterium ulcerans were divided into an untreated control group and 17 treatment groups that received one of the following regimens for 4 weeks (all doses in milligrams per kilogram): 100 mg of azithromycin (AZM), 100 mg of clarithromycin (CLR), or 50 mg of AZM for a duration of 5 days a week (daily), three times a week, or once weekly. In addition, the following regimens were administered daily: 100 mg of telithromycin (TLM), sparfloxacin (SPX), or moxifloxacin (MOX); 200 mg of levofloxacin (LVX); 100 mg of streptomycin (STR) or amikacin (AMK); 10 mg of rifampin (RIF); and the combination of 10 mg of RIF and 100 mg of AMK (RIF+AMK). After completion of treatment, mice were observed for 30 weeks. The effectiveness of treatment regimens was assessed in terms of the delay in median time to footpad swelling in treated mice compared with that in the untreated controls. Clear-cut bactericidal activity, i.e., an observed delay in footpad swelling that exceeded the period of treatment, was observed in the STR-, AMK-, and RIF+AMK-treated mice. However, all mice treated with either AMK or STR alone had swollen footpads before the end of the 30-week observation period, suggesting regrowth of M. ulcerans. In contrast, 50% of the mice treated with the RIF+AMK combination exhibited no lesion even after 30 weeks, suggesting cure. The remaining regimens could be assigned to one of three groups: (i) no activity (50 mg of AZM, 100 mg of AZM thrice weekly, TLM, and LVX); (ii) bacteriostatic activity, i.e., a delay in footpad swelling shorter than the 4-week treatment duration (100 mg of AZM daily or once weekly, CLR thrice or once weekly, and MOX); or (iii) weak bactericidal activity (CLR daily and SPX). The RIF+AMK combination and possibly RIF+STR warrant further study for the treatment of M. ulcerans infection in humans.

Mycobacterium xenopi spinal infections after discovertebral surgery: investigation and screening of a large outbreak

BACKGROUND

Mycobacterium xenopi spinal infections were diagnosed in 1993 in patients who had undergone surgical microdiscectomy for disc hernia, by nucleotomy or microsurgery, in a private hospital. Contaminated tap water, used for rinsing surgical devices after disinfection, was identified as the source of the outbreak. Several cases were recorded in the 4 years after implementation of effective control measures because of the long time between discectomy and case detection. The national health authorities decided to launch a retrospective investigation in patients who were exposed to M xenopi contamination in that hospital.

METHODS

Mailing and media campaigns were undertaken concurrently to trace exposed patients for spinal infections. Patients were screened by magnetic resonance imaging (MRI), and the scans were reviewed by a radiologist who was unaware of the diagnosis. Suspected cases had discovertebral biopsy for histopathological and bacteriological examination.

FINDINGS

Of 3244 exposed patients, 2971 (92%) were informed about the risk of infection and 2454 (76%) had MRI. Overall, 58 cases of M xenopi spinal infection were identified (overall cumulative frequency 1.8%), including 26 by the campaign (mean delay in detection 5.2 years, SD 2.4, range 1-10 years). Multivariate analysis showed that the risk of M xenopi spinal infection was related to nucleotomy and high number of patients per operating session.

INTERPRETATION

Failures in hygiene practices could result in an uncontrolled outbreak of nosocomial infection. Patients who have been exposed to an iatrogenic infectious hazard should be screened promptly and receive effective information.

Iron and Mycobacterium tuberculosis infection

BACKGROUND

iron is known to play a role in the susceptibility to and outcome of several infections. In view of the increasing worldwide problem of tuberculosis, it may be important to ascertain whether this is also the case with this infection.

OBJECTIVES

(1) to review studies conducted in vitro, in experimental animals, and in humans that provide evidence that iron status may influence the occurrence and outcome of tuberculosis. (2) To perform an in vivo study in mice, examining the effect of iron loading on experimental infection caused by a virulent strain of Mycobacterium tuberculosis.

RESULTS

we studied the effect of iron loading on the growth in spleen and lungs of a virulent strain of M. tuberculosis, injected i.v. in female Balb/C mice. At sacrifice on day 42 after the experimental infection, the iron-loaded mice presented a significantly enhanced multiplication of M. tuberculosis in both the spleen and the lungs, when compared to the mice without iron loading.

CONCLUSION

Most of the studies, including our experimental study in mice, tend to suggest that an excess of iron may enhance the growth of M. tuberculosis and worsen the outcome of human tuberculosis.

Mycobacterial growth indicator tube versus the proportion method on Löwenstein-Jensen medium for antibiotic susceptibility testing of Mycobacterium tuberculosis

The Mycobacterial Growth Indicator Tube, a reliable system for detection of mycobacterial growth, was compared with the reference proportion method on Löwenstein-Jensen medium for antibiotic susceptibility testing of Mycobacterium tuberculosis. A total of 62 clinical strains and four reference strains of Mycobacterium tuberculosis were tested for susceptibility to streptomycin, isoniazid, rifampicin and ethambutol. Of these, 36 were susceptible to all four antibiotics and 30 were resistant to at least one of them. Tests were repeated in cases of discrepant results. When each drug/strain combination was considered separately, the overall agreement between the two methods was 96.5% (98.4% for streptomycin, 95.3% for isoniazid, 96.9% for rifampicin and 95.3% for ethambutol) with regard to the initial testing and 98.8% (100, 98.5, 98.5 and 98.4%, respectively) after repeated testing. When the results were considered strain by strain, the agreement was 86% after the initial testing and 95% after repeated testing. The results were obtained after a mean time of 9.5 days. These results suggest that the Mycobacterial Growth Indicator Tube is a reliable method for testing susceptibility of mycobacterial strains to first-line antituberculous drugs.

Combination of rifapentine-moxifloxacin-minocycline (PMM) for the treatment of leprosy

To further the development of a multidrug regimen for treatment of leprosy that is suitable for monthly administration and fully supervisable, the bactericidal activities against Mycobacterium leprae of HMR 3647 (HMR), moxifloxacin (MXFX) and rifapentine (RPT) were measured by the proportional bactericide technique in the mouse footpad system, and compared with those of the established antileprosy drugs clarithromycin (CLARI), ofloxacin (OFLO) and rifampicin (RMP). Administered in five daily doses of 100 mg per kg body weight, HMR appeared slightly more bactericidal than CLARI, but the difference did not attain statistical significance. Administered as single doses, MXFX in a dosage of 150 mg per kg was more active than OFLO in the same dosage, and displayed the same level of activity as RMP in a dosage of 10 mg per kg; the combination MXFX-minocycline (MINO) (MM) was more bactericidal than the combination OFLO-MINO (OM); RPT in a dosage of 10 mg per kg was more bactericidal than RMP administered in the same dosage, and even more active than the combination RMP-OFLO-MINO (ROM); the combination RPT-MXFX-MINO (PMM) killed 99.9% of viable M. leprae, and was slightly more bactericidal than was RPT alone, indicating that the combination PMM showed an additive effect against M. leprae. These promising results justify a clinical trial among lepromatous patients, in which MM is being compared with OM, and PMM with ROM, in terms of efficacy and tolerance.

The new challenges for chemotherapy research

Scientific knowledge is constantly expanding, and needs are changing; therefore, efforts must be made to adapt the treatment of leprosy and the manner in which it is implemented to the newly identified needs. Because an effective vaccine against leprosy remains to be identified, multidrug therapy (MDT) is the only tool available for leprosy control. At present, therefore, the priority is to make MDT available in all endemic countries for all patients, even those living in difficult-to-access areas. The remaining important issues in chemotherapy research are to improve the quality of leprosy case-finding, improve the quality of MDT, identify the areas in which leprosy patients are not receiving proper MDT, and find the means necessary to ensure delivery to all of appropriate MDT. The MDT regimens recommended by the World Health Organization are of too long duration, require correct classification of the patients as PB or MB, and rely upon the daily self-administration of dapsone and clofazimine to prevent selection of rifampicin resistant mutants among MB patients. Thus, research leading to the development of new drug regimens should be directed toward overcoming the shortcomings of the presently recommended regimens. The drugs required to permit use of regimens of shorter duration, that may be employed among both PB and MB patients, and that enable fully supervised drug administration may be already in hand, and the necessary clinical trials to confirm efficacy and acceptability should be carried out.

Bactericidal activities of HMR 3647, moxifloxacin, and rifapentine against Mycobacterium leprae in mice

Bactericidal activities of HMR 3647 (HMR), moxifloxacin (MXFX), and rifapentine (RPT) against Mycobacterium leprae, measured by the proportional bactericidal technique in the mouse footpad system, were compared with those of the established antileprosy drugs clarithromycin (CLARI), ofloxacin (OFLO), and rifampin (RMP). Administered in five daily doses of 100 mg/kg of body weight, HMR appeared slightly more bactericidal than CLARI. In a single dose, MXFX at 150 mg/kg was more active than the same dose of OFLO and displayed exactly the same level of activity as RMP at 10 mg/kg; the combination MXFX-minocycline (MINO) (MM) was more bactericidal than the combination OFLO-MINO (OM); RPT at 10 mg/kg was more bactericidal than the same dose of RMP and even more active than the combination RMP-OFLO-MINO (ROM); the combination RPT-MXFX-MINO (PMM) killed 99.9% of viable M. leprae and was slightly more bactericidal than RPT alone, indicating that the combination PMM showed an additive effect against M. leprae.

Activities of several antimicrobials against Mycobacterium ulcerans infection in mice

Mycobacterium ulcerans inoculated into the footpads of mice at 6 x 10(3) CFU was shown to have a generation time of 6.5 days when estimated from weekly changes in microscopic counts of acid-fast bacilli (AFB) and 7.5 days when calculated from actual CFU enumerated on Lowenstein-Jensen egg medium incubated at 32 degrees C. Footpads became swollen at week 10 (W10) after infection, and all infected control mice were dead at W15 after infection. Daily (5 days/week) treatment with 100 mg of clarithromycin (CLR)/kg of body weight beginning the day after infection prevented swelling of footpads at W10. When initiation of treatment was delayed until obvious footpad swelling was observed, there was a reduction in both the increase in AFB counts and deterioration of swollen footpads and also a prolonged survival of the mice to W18. Mice infected in the hind footpads with 5 x 10(5) CFU of M. ulcerans were divided into an untreated control group and six treatment groups that received one of the following therapies for 8 weeks: 100 mg of CLR/kg, 25 mg of minocycline (MIN)/kg, 50 mg of sparfloxacin (SPX)/kg, 10 mg of rifampin (RIF)/kg, 10 mg of rifabutin (RBT)/kg, or 100 mg of amikacin (AMK)/kg. After completion of therapy, treated animals were observed for an additional 17 weeks. All control mice and mice treated with CLR, MIN, or SPX exhibited swollen footpads during the observation period. In contrast, of those animals treated with RIF, RBT, or AMK, none had footpad swelling and all inoculated cultures done after the W17 observation remained negative. These results suggest that RIF, RBT, and AMK may be effective in the treatment of human infection with M. ulcerans.

[Mycobacterium ulcerans infection]

Mycobacterium ulcerans infection, or Buruli ulcer, is the third most common mycobacterial disease of the immunocompetent host in the tropical areas. M. ulcerans reservoir is aquatic. Infection occurs in children and young adults. The lesion begins with an indolent subcutaneous nodule, principally located on the limbs, that progressively changes into a deep indolent extensive ulcer. M. ulcerans produces a lipidic necrotic and immunosuppressive toxin, named mycolactone, that causes the clinical lesions. In endemic areas, clinical diagnosis is confirmed by microscopic examination. Spontaneous healing occurs after several months or years, causing retractile scars. Surgical excision and grafting is the treatment of choice. Antibiotic therapy is of limited value.

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.

Twenty-five years of tuberculosis in a French university hospital: a laboratory perspective

OBJECTIVE

To determine the impact of recent changes in the epidemiology of tuberculosis in France and other industrialised countries on the primary trends of tuberculosis case rates in a French university hospital.

DESIGN

Descriptive study of all 4549 culture-positive tuberculosis cases hospitalised at Pitié-Salpêtrière Hospital between 1972 and 1996.

RESULTS

From 1972, there was a decline of 5% per year in the tuberculosis case rate, which levelled off in 1983. The proportion of tuberculosis patients who were human immunodeficiency virus (HIV) positive increased from 2% in 1983 to 28% in 1990, and thereafter remained stable. The proportion of foreign-born tuberculosis patients also increased, from 40% in 1972 to 55% in 1985. These two changes affected drug resistance patterns. Drug resistance was more common among foreign-born than among French-born patients, whether previously treated or not. Resistance to rifampicin and multidrug resistance among previously untreated patients was highly related to HIV co-infection. Extrapulmonary sites of tuberculosis were more often smear-positive in HIV-positive than in non-HIV-positive patients (22.8% vs 12.6%), and bacteraemia was diagnosed almost exclusively in HIV-positive patients.

CONCLUSION

The changes in clinical and bacteriological tuberculosis patterns at the hospital level over the last 25 years have paralleled those observed at national and international level in industrialised countries, including a slowing in the decrease in the case rate, due in part to the HIV epidemic, a higher proportion of foreign-born patients and an increase in drug resistance.

Antituberculosis activity of once-weekly rifapentine-containing regimens in mice. Long-term effectiveness with 6- and 8-month treatment regimens

The effectiveness of various once-weekly 10 mg/kg rifapentine (P)- containing regimens for treatment of tuberculosis was assessed in mice infected intravenously with 4.3 x 10(6) colony-forming units (cfu) of Mycobacterium tuberculosis H37Rv, and treated 14 d later with various combinations of rifampin (R), P, isoniazid (H), pyrazinamide (Z), ethambutol (E), or streptomycin (S). Control mice treated daily with either 2-mo HRZ + 4-mo HR or 2-mo HRZ + 6-mo HE were rendered spleen and lung culture-negative at 6 mo and 8 mo, respectively. Treatment failure with emergence of R-resistant bacilli occurred in all mice given once-weekly monotherapy with P for 6 mo. Once-weekly PH treatment was successful at 6 mo when it was preceded by a 2-mo daily phase with HRZ. When the initial daily phase was reduced to 2 wk, once-weekly PH-containing treatment was successful, at 6 mo, only if it was supplemented with S during the initial daily and the once-weekly phases, and at 8 mo if it was supplemented with daily H during the once-weekly phase. Without these supplements, once-weekly treatment failed in some mice with selection of R-resistant or H-resistant mutants.

[Which strategies for eradication of tuberculosis?]

Eradication of tuberculosis is biologically feasible because infectious tuberculosis is relatively easy to identify, is treatable and curable, with cure rates approaching 100% when modern short-course therapy is used. Early diagnosis and effective treatment reduce transmission. Infected persons at increased risk of developing infectious tuberculosis can be identified through tuberculin screening of high-risk populations and tuberculosis is, at least partly, preventable by the administration of preventive therapy (chemoprophylaxis) and BCG vaccination. Humans are the primary reservoir of the tubercle bacillus. In industrialized countries, tuberculin testing of dairy cattle and slaughter of infected animals and pasteurization of milk have virtually eliminated the problem. In industrialized countries, tuberculosis has retreated into focal pockets that can be targeted for intensified control efforts. Elimination of tuberculosis in these countries depends in part on global elimination because of imported cases. In developing countries, the immediate task is to control tuberculosis, and DOTS is the key detection and treatment strategy. Joint efforts should address the issue of the global implementation of DOTS strategy and of the research needs for effective vaccine, new drugs and new delivery services.

Outcome of multi-drug-resistant tuberculosis in France: a nationwide case-control study

The factors related to the outcome of 51 cases of multi-drug-resistant tuberculosis (MDR-TB) reported in 1994 to the French National Reference Center were retrospectively analyzed. The patients (median age, 45 yr) were mainly male (75%), foreign-born (63%), and had pulmonary involvement (95%). Sixteen percent were human immunodeficiency virus (HIV)-coinfected. The number of drugs to which the Mycobacterium tuberculosis isolates were susceptible was four. Only 82% of the patients have been hospitalized at any time (median duration, 33 d). Five patients (9%) received no antituberculosis drugs, although three had drug susceptibility results, indicating that two or more active drugs were available; 46 (91%) received drugs, including 37 who received two or more active drugs. Among the nine cases who received only one active drug, three had drug susceptibility results, indicating that two or more active drugs were available. By December 1996, 10 patients were lost before treatment completion, 24 had treatment failure, and 17 had a favorable outcome. The median survival time was 31 mo. Factors related to a poorer outcome were HIV-coinfection (hazard ratio [HR] = 41), treatment with less than two active drugs (HR = 9.9), and MDR status knowledge at the time of diagnosis (HR = 3.3). The country of birth was not associated with a poorer outcome. The management and outcome of MDR-TB in France has to be improved. A solution would be to develop a specialized unit or team for the treatment of MDR-TB, as recommended by the World Health Organization (WHO).