[Bacteriological tests for tuberculosis]

This review describes current developments for the bacteriological diagnosis of active tuberculosis. It deals mainly with molecular methods, describing their performance and how they can be integrated into more traditional diagnostic approaches. At present, microscopic examination and culture are still essential for the diagnosis of TB and to guide therapeutic decisions. Nucleic acid amplification and line probe assays speed up the identification and susceptibility testing of mycobacteria in AFB smear positive specimens or in culture. They are also efficient for comparison of M. tuberculosis strains with each other (genotyping). On the other hand, at present, molecular tests are not applicable for diagnosis in smear negative specimens and even less so for diagnosis of culture-negative tuberculosis. The use of serology for antibody/antigen detection is not useful and it is not appropriate to assays based on the release of interferon-γ release as they are currently available. Notable progress has been made but more sensitive diagnostic tests for TB are still urgently needed.

Sterilizing activity of R207910 (TMC207)-containing regimens in the murine model of tuberculosis

RATIONALE

The diarylquinoline R207910 (TMC207) has potent bactericidal activity in a murine model of tuberculosis (TB), but its sterilizing activity has not been determined.

OBJECTIVES

To evaluate the sterilizing activity of R207910-containing combinations in the murine model of TB.

METHODS

Swiss mice were intravenously inoculated with 6 log(10) of Mycobacterium tuberculosis strain H37Rv, treated with R207910-containing regimens, and followed for 3 months to determine relapse rates (modified Cornell model).

MEASUREMENTS AND MAIN RESULTS

Quantitative lung and spleen colony-forming unit counts and bacteriological relapse rates 3 months after the end of therapy were compared for the following regimens: 2, 3, or 4 months of R207910 (J) and pyrazinamide (Z) combined with rifampin (R) or isoniazid (H) or both and 3 or 4 months of a moxifloxacin (M)-containing regimen and 6 months of the standard WHO regimen RHZ. All J-treated mice were culture negative after 4 months of therapy. The relapse rate in the group treated with 4 months of JHRZ was similar to that of mice treated for 6 months with the RHZ regimen (6 vs. 17%; P = 0.54) and lower than that of RMZ (6 vs. 42%; P = 0,03), a moxifloxacin-containing regimen that was the most active in mice on once-daily basis.

CONCLUSIONS

Four months of treatment with some J-containing regimens was as effective as the 6-month standard regimen and more effective than 4 months of treatment with M-containing regimens. Supplementation of standard regimen (RHZ) with J or substitution of J for H may shorten the treatment duration needed to cure TB in patients.

A once-weekly R207910-containing regimen exceeds activity of the standard daily regimen in murine tuberculosis

RATIONALE

R207910 (TMC207 or J) is a member of the diarylquinolines, a new family of antituberculous drugs with high bactericidal activity when given daily in the murine model of tuberculosis. R207910 exhibits a long half-life and thus is a good candidate for once-weekly therapy of tuberculosis.

OBJECTIVES

To study the activity of once-weekly R207910 monotherapy and combinations of R207910 with other antituberculous agents (isoniazid, rifapentine, moxifloxacin, and pyrazinamide).

METHODS

The established infection model of murine tuberculosis was used. Colony counts were determined in the lungs.

MEASUREMENTS AND MAIN RESULTS

Eight weeks of monotherapy reduced the bacillary load by 3 to 4 log(10) for rifapentine and by 5 to 6 log(10) for R207910 (P < 0.05). The addition of rifapentine and isoniazid or moxifloxacin did not improve the bactericidal activity of R207910 monotherapy. In contrast, the triple combination of R207910 plus rifapentine plus pyrazinamide given once weekly for 2 months (i.e., a total of only eight administrations), was significantly (P < 0.05) more active than R207910 monotherapy or other R207910 combinations, and led to lung culture negativity in 9 of 10 mice, whereas all lungs were culture positive in the groups treated with other drug combinations. Moreover, R207910 plus rifapentine plus pyrazinamide given once weekly was more active than the current standard regimen of rifampin plus isoniazid plus pyrazinamide given five times per week.

CONCLUSIONS

The unprecedented activity of the triple combination of R207910 plus rifapentine plus pyrazinamide suggests that it may be feasible to develop a fully intermittent once-weekly regimen.

A 10-year prospective surveillance of Mycobacterium tuberculosis drug resistance in France 1995 2004

Drug resistance surveillance and trend monitoring resistance rates bring some insights into tuberculosis (TB) control. The current study reports the characteristics of TB and drug resistance during a 10-yr prospective surveillance of culture-positive TB in France. Data for the current study was collected from 1995-2004 via a sentinel network of laboratories from university hospitals that complied with the international recommendations for the surveillance of drug resistance. Susceptibility test results were performed in each individual laboratory. Data on 13,283 patients were collected during the 10-yr period, 49% of whom had been born in France, 10% were HIV co-infected and 8% had previously been treated. As expected, previously treated and HIV co-infected patients were more likely to harbour resistant strains, especially rifampicin (RMP)-resistant strains. Among new patients, the mean resistance rate to at least one drug was 8.8%, and there was an upward trend in resistance to isoniazid and RMP (0.8-1%) related to the increase in the proportion of patients who had been born outside of France (38-53%). Among previously treated patients, the mean resistance rate to one drug was 20.6% and there was no significant time trend in resistance rates. The sentinel network provided valuable data on trends regarding the characteristics of tuberculosis and on drug resistance rates and reinforced the interest of analysing data by country of birth and history of treatment.

An intervention programme for the management of multidrug-resistant tuberculosis in France

As shown in a previous study, the outcome of multidrug-resistant tuberculosis (MDR-TB) in France is not satisfactory (41% success rate). To improve the management and outcome of patients with MDR-TB, a prospective intervention study was carried out in 1998-1999 by National Reference Centre (NRC) staff. NRC staff contacted (i) the microbiologists reporting MDR-TB patients in order to offer second-line drug testing and (ii) physicians to help tailor treatment regimens based on World Health Organization guidelines. A total of 45 MDR-TB patients were followed, including 33 for whom NRC staff successfully interacted with the physicians in charge and 12 patients managed without NRC collaboration. The crude proportion of favourable outcomes was 58%, and this proportion reached 70% for patients managed in collaboration with the NRC. Among the latter 33 patients, 32 were treated with at least three active drugs for a median duration of 12 months. In multivariate analysis, HIV-positive status was associated with treatment failure (hazard ratio (HR) 4.3), whereas NRC intervention was associated with a favourable outcome (HR 0.2). However, even in the NRC intervention group the median duration of treatment was shorter than planned (median 12 months) and 12% of patients were lost to follow-up. This intervention study provides encouraging results and should be continued until reference teams and a directly observed treatment strategy (DOTS) are implemented to improve patient management further.

Synergistic activity of R207910 combined with pyrazinamide against murine tuberculosis

In previous studies, the diarylquinoline R207910 (also known as TMC207) was demonstrated to have high bactericidal activity when combined with first- or second-line antituberculous drugs. Here we extend the evaluation of R207910 in the curative model of murine tuberculosis by assessing the activities of one-, two-, and three-drug combinations containing R207910 and isoniazid (INH), rifampin (RIF), pyrazinamide (PZA), or moxifloxacin (MXF) in the setting of a high initial bacillary load (7.2 log(10) CFU). Two months of treatment with the combinations R207910-PZA, R207910-PZA-INH, R207910-PZA-RIF, or R207910-PZA-MXF resulted in culture-negative lung homogenates in 70 to 100% of the mice, while mice treated with INH-RIF-PZA (the reference regimen) or RIF-MXF-PZA remained culture positive. Combinations including R207910 but not PZA (e.g., R207910-INH-RIF and R207910-MXF-RIF) were less active than R207910-PZA-containing regimens administered either alone or with the addition of INH, RIF, or MXF. These results reveal a synergistic interaction between R207910 and PZA. Three-drug combinations containing these two drugs and INH, RIF, or MXF have the potential to significantly shorten the treatment duration in patients, provided that these results can be confirmed in long-term experiments including periods of relapse.

Performance of the genotype MTBDR line probe assay for detection of resistance to rifampin and isoniazid in strains of Mycobacterium tuberculosis with low- and high-level resistance

We assessed the performance of the Genotype MTBDR line probe assay that offers the simultaneous identification of Mycobacterium tuberculosis and its resistance to rifampin (RIF) and isoniazid (INH) by detecting the most commonly found mutations in the rpoB and katG genes. One hundred thirteen M. tuberculosis isolates were tested. The nucleotide sequences of the katG and inhA genes and the mabA-inhA promoter region were also determined. The MTBDR assay detected 100% and 67% (n = 64) of the strains resistant to RIF and INH, respectively. Among the latter, 62 strains carried a Ser315Thr mutation in katG, 59 of them displaying a high level of resistance to INH. Two strains with a low level of INH resistance had a Ser315Asn mutation. No mutation was found by the MTBDR assay for 31 INH-resistant strains (33%), of which 24 showed a low level of resistance. By DNA sequencing, we found among them various mutations in the KatG protein for 7 strains, a C-->T mutation in position -15 of the mabA-inhA promoter in 17 strains, and a Ser94Ala mutation in InhA for 7 strains. In conclusion, the MTBDR assay, which fits easily in the workflow of a routine laboratory, enabled the detection of 100% of the RIF-resistant strains and 89% of the INH-resistant strains with a high level of resistance but only 17% of the strains characterized by a low level of INH resistance, indicating that the test can be used as a rapid method to detect in the same experiment the rifampin-resistant and the high-level isoniazid-resistant strains of M. tuberculosis.

[Trends in tuberculosis treatment duration]

The two principal characteristics of tuberculosis treatment are its length (several months) and the need to use several antibiotics simultaneously (multiple drug therapy). Multiple drug therapy is intended to prevent the selection of resistant mutants at the beginning of treatment, when the bacilli population is largest. The length of treatment is due to dormant bacilli, which are much more difficult for antibiotics to kill than actively multiplying bacilli are. Rifampin and pyrazinamide are the most potent drugs against these dormant bacilli. The so-called sterilizing activity of rifampin has reduced the duration of treatment from 18 to 9 months, and the contribution of pyrazinamide reduced this time still further, to 6 months. When one of these drugs cannot be used because of resistance or toxicity, duration of treatment increases to the earlier levels. In the extreme case of multidrug-resistant tuberculosis where neither isoniazid nor rifampin can be used, and sometimes even not pyrazinamide, treatment is recommended for 18 to 24 months. New antituberculosis drugs under development allow us to envision further reduction in the duration of treatment of both drug-resistant and drug-sensitive tuberculosis.

Diagnostic moderne de la tuberculose

Microscopic examination of sputum smears (search for acid-fast bacilli or AFB) is the most rapid procedure for diagnosis of contagious tuberculosis. Gene amplification is not yet reliable for direct detection of M. tuberculosis in clinical specimens that are AFB smear-negative. Culture (3 to 8 weeks on Lowenstein-Jensen medium or 1 to 4 weeks in liquid media) remains essential to identify AFB and conduct antibiotic susceptibility testing. AFB from culture can be identified in a few hours by molecular approaches with specific DNA probes. Results of susceptibility testing, even in liquid media, are not available until 2 to 4 weeks after the recovery of specimens, although mutations of the rpoB and katG 315 genes, which confer resistance to rifampin and isoniazid, can be detected within hours by molecular hybridization with specific probes fixed on strips. Immunologic tests that measure the interferon gamma produced by sensitized lymphocytes are promising tools for the diagnosis of latent tuberculosis.

Hip prosthesis infection due to Mycobacterium wolinskyi

Mycobacterium wolinskyi, first described in 1999, is a rapidly growing mycobacterium related to the Mycobacterium smegmatis group. Only eight cases of infection due to this microorganism have been reported, including three cases of bone infection. Here, we present the first case of a joint prosthesis infection cured with the combination of surgery and prolonged antibiotic therapy. The microorganism was identified by biochemical tests and 16S rRNA and Hsp65 gene sequence analysis.

Functional analysis of DNA gyrase mutant enzymes carrying mutations at position 88 in the A subunit found in clinical strains of Mycobacterium tuberculosis resistant to fluoroquinolones

We investigated the enzymatic efficiency and inhibition by quinolones of Mycobacterium tuberculosis DNA gyrases carrying the previously described GyrA G88C mutation and the novel GyrA G88A mutation harbored by two multidrug-resistant clinical strains and reproduced by site-directed mutagenesis. Fluoroquinolone MICs and 50% inhibitory concentrations for both mutants were 2- to 43-fold higher than for the wild type, demonstrating that these mutations confer fluoroquinolone resistance in M. tuberculosis.

Combinations of R207910 with drugs used to treat multidrug-resistant tuberculosis have the potential to shorten treatment duration

The objective of the present study was to identify the optimal R207910-containing regimen to administer to patients who cannot receive rifampin (RIF) and isoniazid (INH) because of multidrug-resistant tuberculosis (MDR-TB), concomitant use of antiretroviral drugs, or toxicity. Mice were infected intravenously with 5 x 10(6) CFU of the H37Rv strain and treated five times per week with R207910 alone or various combinations of R207910 with the second-line drugs amikacin (AMK), pyrazinamide (PZA), moxifloxacin (MXF), and ethionamide (ETH). All R207910-containing regimens were significantly more active than the non-R207910-containing regimens after 1 month of therapy. When given for 2 months, R207910 alone was more active than the WHO standard first-line regimen RIF-INH-PZA. When R207910 was combined with second-line drugs, the combinations were more active than the currently recommended regimen of MDR-TB AMK-ETH-MXF-PZA, and culture negativity of both the lungs and spleen was reached after 2 months of treatment in almost every case.

Novel gyrase mutations in quinolone-resistant and -hypersusceptible clinical isolates of Mycobacterium tuberculosis: functional analysis of mutant enzymes

Mutations in the DNA gyrase GyrA2GyrB2 complex are associated with resistance to quinolones in Mycobacterium tuberculosis. As fluoroquinolones are being used increasingly in the treatment of tuberculosis, we characterized several multidrug-resistant clinical isolates of M. tuberculosis carrying mutations in the genes encoding the GyrA or GyrB subunits associated with quinolone resistance or hypersusceptibility. In addition to the reported putative quinolone resistance mutations in GyrA, i.e., A90V, D94G, and D94H, we found that the GyrB N510D mutation was also associated with ofloxacin resistance. Surprisingly, several isolates bearing a novel combination of gyrA T80A and A90G changes were hypersusceptible to ofloxacin. M. tuberculosis GyrA and GyrB subunits (wild type [WT] and mutants) were overexpressed in Escherichia coli, purified to homogeneity, and used to reconstitute highly active gyrase complexes. Mutant proteins were produced similarly from engineered gyrA and gyrB alleles by mutagenesis. MICs, enzyme inhibition, and drug-induced DNA cleavage were determined for moxifloxacin, gatifloxacin, ofloxacin, levofloxacin, and enoxacin. Mutant gyrase complexes bearing GyrA A90V, D94G, and D94H and GyrB N510D were resistant to quinolone inhibition (MICs and 50% inhibitory concentrations [IC50s] at least 3.5-fold higher than the concentrations for the WT), and all, except the GyrB mutant, were less efficiently trapped as a quinolone cleavage complex. In marked contrast, gyrase complexes bearing GyrA T80A or A90G were hypersusceptible to the action of many quinolones, an effect that was reinforced for complexes bearing both mutations (MICs and IC50s up to 14-fold lower than the values for the WT). This is the first detailed enzymatic analysis of hypersusceptibility and resistance in M. tuberculosis.

MYCOBACTERIUM SZULGAI INFECTION IN A CAPTIVE POPULATION OF AFRICAN CLAWED FROGS (XENOPUS TROPICALIS)

A colony of captive Xenopus tropicalis became infected with Mycobacterium szulgai. Clinical signs, when observed, were lethargy, weight loss, and emaciation. Visceral granulomas were common findings at laparoscopy and necropsy. The diagnosis of mycobacteriosis was based on histologic appearance and Ziehl-Neelsen staining of tissues. The identification of M. szulgai organisms was based on comparison of the 16S rRNA gene sequence with several GenBank databases. There have been no reports of this mycobacterial species as the causative agent of naturally occurring disease in amphibians.

Efficient intermittent rifapentine-moxifloxacin-containing short-course regimen for treatment of tuberculosis in mice

Long-half-life drugs raise the hope of once-a-week administration of antituberculous treatment. In a previous study with the murine model of tuberculosis, the most active intermittent regimen which contained rifapentine (RFP), isoniazid (INH), and moxifloxacin (MXF) given once a week during 5.5 months, preceded by 2 weeks of daily treatment with INH, rifampin (RIF), pyrazinamide (PZA), and MXF, was less active than the standard 6-month daily RIF-INH-PZA regimen. We evaluated with the same model similar regimens in which we increased the dosing of rifapentine from 10 to 15 mg/kg of body weight and of moxifloxacin from 100 to 400 mg/kg. Mice infected intravenously by 6.2 x10(6) CFU of Mycobacterium tuberculosis H37Rv were treated 2 weeks later when infection was established. After 6 months of treatment, all mice had negative lung culture. After 3 months of follow-up, no relapse occurred in the two groups that received moxifloxacin at 400 mg/kg, whatever the dosage of RFP, and in the group receiving the standard RIF-INH-PZA control regimen. In contrast, in the two groups receiving moxifloxacin at a lower dosage, the relapse rate was significantly higher (13% in mice receiving RFP at 15 mg/kg and 27% in those receiving RFP at 10 mg/kg). Finally, the fully intermittent once-a-week regimen (26 drug ingestions) of INH, RFP (15 mg/kg), and MXF (400 mg/kg) led to a relapse rate of 11%. In conclusion, when used at high dosage, rifapentine and moxifloxacin are very efficient when combined with isoniazid in a once-a-week treatment in mouse tuberculosis.

Outbreak of tuberculosis in a migrants' shelter, Paris, France, 2002

SETTING

An overcrowded 362-bed migrants' shelter in Paris, France.

OBJECTIVES

To investigate an outbreak of tuberculosis (TB), to identify a common source of contamination and to prevent further transmission.

METHODS

The outbreak was identified by radiographic screening and an active search for undeclared hospital treated cases, completed by strain phenotyping and a search for contact cases.

RESULTS

Between October 2001 and October 2002, 56 cases of active TB were identified, 30 by radiological screening and 20 by contacting neighbouring hospitals. All cases involved men, with a median age of 30 years. Pulmonary involvement was present in 54% of cases, and nine patients were sputum smear-positive. Thirty-four of the 37 phenotyped strains clustered together.

CONCLUSION

The grouping of the cases in time and place, the large number of cases with early-stage disease and the identical RFLP banding patterns of most of the isolates indicate that this outbreak results from transmission that occurred in France. This report underlines the need for public health departments in industrialised countries to maintain effective anti-tuberculosis control programmes.

First isolation of Mycobacterium microti (Llama-type) from a dog

We report the first isolation of Mycobacterium microti from a dog with lesions of acute peritonitis. The isolate was demonstrated to be M. microti of Llama-Type by spoligotyping. Epidemiological implications of the isolation of this possibly zoonotic agent from a dog are discussed.

A diarylquinoline drug active on the ATP synthase of Mycobacterium tuberculosis

The incidence of tuberculosis has been increasing substantially on a worldwide basis over the past decade, but no tuberculosis-specific drugs have been discovered in 40 years. We identified a diarylquinoline, R207910, that potently inhibits both drug-sensitive and drug-resistant Mycobacterium tuberculosis in vitro (minimum inhibitory concentration 0.06 mug/ml). In mice, R207910 exceeded the bactericidal activities of isoniazid and rifampin by at least 1 log unit. Substitution of drugs included in the World Health Organization's first-line tuberculosis treatment regimen (rifampin, isoniazid, and pyrazinamide) with R207910 accelerated bactericidal activity, leading to complete culture conversion after 2 months of treatment in some combinations. A single dose of R207910 inhibited mycobacterial growth for 1 week. Plasma levels associated with efficacy in mice were well tolerated in healthy human volunteers. Mutants selected in vitro suggest that the drug targets the proton pump of adenosine triphosphate (ATP) synthase.

Use of a high-density DNA probe array for detecting mutations involved in rifampicin resistance in Mycobacterium tuberculosis

A Mycobacterium high-density DNA probe array designed to detect rpoB mutations conferring rifampicin resistance in Mycobacterium tuberculosis was evaluated. The rpoB hybridisation patterns produced by 41 susceptible (RifS) and 59 rifampicin-resistant (RifR) clinical isolates of M. tuberculosis were compared with the results of conventional dideoxynucleotide sequencing of the rpoB gene. For all the RifR isolates, the rpoB hybridisation patterns correlated with the rpoB sequencing results. Among the 59 isolates, 11 distinct amino-acid changes were detected by the DNA probe array. Of these, 36 (61%) corresponded to replacement of the serine residue found in position 531 (S531L in 34 isolates and S531W in two isolates), 16 (27%) affected histidine 526 (five H526D, five H526Y, four H526L, one H526N and one H526R), four (6.8%) replaced aspartate 516 with a valine, and one (1.7%) replaced glutamine 513 with a leucine. Deletion of the asparagine residue at position 519 was detected in one isolate susceptible to rifampicin, but yielding c. 0.1% resistant colonies on rifampicin-containing medium. No mutation was detected in the rpoB region from one isolate yielding c. 5% of resistant colonies on rifampicin-containing medium. Finally, a D516Y substitution was detected in association with an unexpected mutation, G523W, not tiled on the DNA probe array, but which could be detected by analysing the hybridisation pattern obtained with the wild-type probes covering codon 523. In conclusion, the Mycobacterium probe array is a promising approach to rapid detection of mutations involved in rifampicin resistance in M. tuberculosis.

[Mycobacterium fortuitum skin infection occurring after a facelift]

INTRODUCTION

Mycobacterium fortuitum skin infections are rare and usually iatrogenic. We report a case with cervical involvement following a facelift.

OBSERVATION

A 65 year-old woman, without past history, underwent bilateral surgical facelift, complicated by cutaneous necrosis and treated with directed healing at home. Six weeks later, an abscessed nodule appeared under the left maxillary and was drained surgically. Then other pre-auricular and left cervical inflammatory nodules appeared without adenopathy or fever. M. fortuitum was isolated in bacteriological samples. The initially probabilistic antibiotherapy with carithromycin, subsequently adapted with amikacine and cirprofloxacine and then imipeneme for a total duration of 3 months, led to the clinical cure.

DISCUSSION

Mycobacterium fortuitum is a rapidly growing, ubiquitous, mycobacteria responsible for nosocomial infections in immunocompetent patients, notably following plastic surgery. Contamination occurs where there has been a rupture in the skin barrier through contact with a vector (water, surgical material, antiseptic.). Treatment, which is not codified, consists in the association of surgery and antibiotics for several months.

Fluoroquinolone-containing third-line regimen against Mycobacterium tuberculosis in vivo

The objective of the present study was to compare the activities of a third-line regimen recommended by the World Health Organization (WHO) and two derivatives of that regimen with the activity of the standard combination of isoniazid, rifampin, and pyrazinamide as a positive control against Mycobacterium tuberculosis in a murine model. The WHO regimen combines ofloxacin (OFX), ethionamide, amikacin, and pyrazinamide; in the two derivatives of this regimen, OFX was replaced by levofloxacin (LVX) or moxifloxacin (MXF). The four drugs, a fluoroquinolone (either OFX, LVX, or MXF), ethionamide, pyrazinamide, and amikacin, were administered for the first 2 months (initial phase); and two drugs, a fluoroquinolone (either OFX, LVX, or MXF) and ethionamide, were administered for the following 10 months (continuation phase). After 6 months of treatment, only the spleens and lungs of mice treated with the standard regimen became culture negative. From 9 months onward, all of the organs of mice treated with the MXF-containing third-line regimen were culture negative. The majority of organs from mice treated with the OFX-containing regimen continued to be culture positive, and the mean CFU counts remained unchanged for as long as 12 months. The results for mice treated with the LVX-containing regimen fell between those for the groups receiving the MXF- and OFX-containing regimens. In conclusion, the activity of the OFX-containing third-line regimen against M. tuberculosis was rather weak in vivo, whereas when OFX was replaced by MXF, 9 months of treatment with a modified third-line regimen displayed bactericidal activity comparable to that of 6 months of treatment with the standard regimen in mice. The MXF-containing third-line regimen seems to be a powerful alternative for the treatment of tuberculosis (TB) when isoniazid and rifampin cannot be used, which is the main feature of multidrug-resistant TB.

Multidrug-resistant tuberculosis: eight years of surveillance in France

The aim of this study was to evaluate the annual prevalence of multidrug-resistant tuberculosis (MDRTB) and to describe the characteristics of the patients with MDRTB in France. Annual questionnaire surveys from 1992-1999 were mailed to all French microbiological laboratories performing mycobacterial cultures. A total of 264 distinct patients were reported to the National Reference Centre for Resistance of Mycobacteria to Antituberculosis Drugs during the 8-yr surveillance period resulting in a mean annual prevalence of MDRTB of 0.6%. A mean of 16% of the MDRTB patients were reported over several subsequent years. The majority of patients were male (69.7%), foreign-born (55.7%), with a previous history of treatment (65.9%), and pulmonary involvement (92.8%) with smear-positive results (59.1%). Human immunodeficiency virus (HIV) coinfection was present in 20.8% of the patients. Strains were resistant only to isoniazid and rifampin in 37.9% of the cases, and additional resistance to both streptomycin and ethambutol was present in 25.8%. HIV coinfection and female status were statistically associated with primary resistance, whereas smear-positive results were associated with secondary resistance. Foreign-birth and smear-positive results were associated with a chronic status. The prevalence of multidrug-resistant tuberculosis is low in France (<1%). However, a substantial proportion of patients remain positive for several years, suggesting nonoptimal management. Therefore, as recommended by the World Health Organization, a few reference teams, working in collaboration with national associations of physicians and microbiologists, should be established to improve the outcome of multidrug-resistant tuberculosis.

Multiple cerebral abscesses as a complication of Mycobacterium fortuitum infection

Mycobacterium fortuitum is a rapidly growing, nontuberculous mycobacteria that has rarely been associated with central nervous system impairment. We describe the case of a patient who developed multiple cerebral abscesses revealing Mycobacterium fortuitum infection. Brain biopsy specimens showed suppurative, noncaseating, granulomatous inflammation consisting of epithelioid histiocytes and multinucleated giant cells. All clinical signs and CT scan cerebral lesions disappeared after institution of appropriate antimycobacterial therapy.

Disseminated infection with a mycobacterium related to Mycobacterium triplex with central nervous system involvement associated with AIDS

We report on a case of disseminated infection with central nervous system involvement due to an atypical mycobacterium related to Mycobacterium triplex in a severely immunodepressed human immunodeficiency virus-infected man.

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.

Identification of mycobacterial species by PCR sequencing of quinolone resistance-determining regions of DNA gyrase genes

The determination of the amino acid sequence of quinolone resistance-determining regions (QRDRs) in the A and B subunits of DNA gyrase is the molecular test for the detection of fluoroquinolone resistance in mycobacteria. We looked to see if the assignment of mycobacterial species could be obtained simultaneously by analysis of the corresponding nucleotide sequences. PCR sequencing of gyrA and gyrB QRDRs was performed for 133 reference and clinical strains of 21 mycobacterial species commonly isolated in clinical laboratories. Nucleotide sequences of gyrA and gyrB QRDRs were species specific, regardless of fluoroquinolone susceptibility.

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.

Rapid, simple, and culture-independent detection of rpsL codon 43 mutations that are highly predictive of streptomycin resistance in Mycobacterium tuberculosis

The substitution of codon 43 in the gene rpsL is the single most common mutation found in streptomycin-resistant Mycobacterium tuberculosis. The characterization of this mutation has been hampered by the need for prior cultivation of the mycobacteria, the need for DNA sequencing, or both. In this report we describe a simple and culture-independent technique to detect this mutation directly from sputum samples, requiring little more than a polymerase chain reaction (PCR) machine and a simple agarose minigel. There is no need for labeled probes or DNA sequencing. In a preliminary test of feasibility, interpretable results were obtained from all of 16 smear-positive and 1 of 4 smear-negative, culture-positive samples. Two of two samples containing M. tuberculosis with rpsL codon 43 mutations were correctly identified.

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.

Antibiotic susceptibility pattern of Mycobacterium marinum

In vitro activities of 17 antibiotics against 53 clinical strains of Mycobacterium marinum, an atypical mycobacterium responsible for cutaneous infections, were determined using the reference agar dilution method. Rifampin and rifabutin were the most active drugs (MICs at which 90% of the isolates tested were inhibited [MIC(90)s], 0.5 and 0.6 microgram/ml, respectively). MICs of minocycline (MIC(90), 4 microgram/ml), doxycycline (MIC(90), 16 microgram/ml), clarithromycin (MIC(90), 4 microgram/ml), sparfloxacin (MIC(90), 2 microgram/ml), moxifloxacin (MIC(90), 1 microgram/ml), imipenem (MIC(90), 8 microgram/ml), sulfamethoxazole (MIC(90), 8 microgram/ml) and amikacin (MIC(90), 4 microgram/ml) were close to the susceptibility breakpoints. MICs of isoniazid, ethambutol, trimethoprim, azithromycin, ciprofloxacin, ofloxacin, and levofloxacin were above the concentrations usually obtained in vivo. For each drug, the MIC(50), geometric mean MIC, and modal MIC were very close, showing that all the strains had a similar susceptibility pattern. Percent agreement (within +/-1 log(2) dilution) between MICs yielded by the Etest method and by the agar dilution method used as reference were 83, 59, 43, and 24% for minocycline, rifampin, clarithromycin, and sparfloxacin, respectively. Reproducibility with the Etest was low, in contrast to that with the agar dilution method. In conclusion, M. marinum is a naturally multidrug-resistant species for which the agar dilution method is more accurate than the Etest for antibiotic susceptibility testing.

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.

A national survey of human Mycobacterium bovis infection in France. Network of Microbiology Laboratories in France

OBJECTIVE

To evaluate the role of Mycobacterium bovis in the epidemiology of human tuberculosis in France.

DESIGN

A national survey in France in 1995 using a questionnaire mailed to all French microbiological laboratories performing mycobacteria cultures.

RESULTS

M. bovis was isolated in 38 out of 7075 cases of bacteriologically confirmed tuberculosis (0.5%) notified to the National Reference Centre (CNR) in 1995, resulting in an incidence of 0.07 per 100,000 population. Incidence rates increased with age, and were the highest among patients of 75 years or more (range 0.02-0.33/100,000). Two cases of tuberculosis due to M. bovis were reported in foreign-born children who had come to France for treatment of their disease. No cases were reported among French-born children. The site of tuberculosis was pulmonary in 17 cases, extra-pulmonary in 14, both pulmonary and extra-pulmonary in one, and unknown in six. Extra-pulmonary sites were more frequent in older patients, and pulmonary sites more frequent in younger patients. Two patients were coinfected with the human immunodeficiency virus. Occupational exposure was identified in 13 cases and ingestion of non pasteurised milk in three. In addition, 11 patients had a possible risk of exposure related to their country of birth, family contact or occupation.

CONCLUSION

In France, the 0.5% proportion of human tuberculosis due to M. bovis is similar to that of other developed countries. The higher incidence of the disease among older people is likely to reflect the efficacy of the control measures for tuberculosis in cattle.

Characterization of new mutations in pyrazinamide-resistant strains of Mycobacterium tuberculosis and identification of conserved regions important for the catalytic activity of the pyrazinamidase PncA

A new set of mutations, including transposition of the insertion sequence IS6110, was identified in the pncA gene from 19 pyrazinamide-resistant Mycobacterium tuberculosis strains. Alignment of the PncA protein from M. tuberculosis with homologous proteins from different bacterial species revealed three highly conserved regions in PncA which may play an important role in the processing of pyrazinamide.

Evaluation of the new MB redox system for detection of growth of mycobacteria

We evaluated a new mycobacterial culture system, MB Redox, for recovery rate and time to detection of mycobacteria from 742 consecutive respiratory specimens and compared the results to those found with Löwenstein-Jensen (LJ) medium. Twenty specimens (2.7%) were positive for M. tuberculosis: 17 on LJ medium and 19 in MB Redox, with 16 specimens positive in both media. In addition, 24 specimens (3.2%) were positive for nontuberculous mycobacteria (NTM), 20 on LJ medium, 18 in MB Redox, and 14 in both media. For M. tuberculosis, the mean times to detection were 28.9 days on LJ medium and 23.6 days in MB Redox, and for NTM, the mean times to detection were 40.6 days on LJ medium and 32.3 days in MB Redox.

Impacts of interleukin-12 on multiplication of Mycobacterium tuberculosis and Mycobacterium avium complex in mice

OBJECTIVE: To evaluate the potential impacts of exogenous administration of murine recombinant interleukin-12 (IL-12) on multiplication of Mycobacterium tuberculosis and M. avium complex (MAC) in murine models. METHODS: Swiss or beige mice were infected intravenously with M. tuberculosis H37Rv or MAC respectively, and were treated by subcutaneous injection with various doses of IL-12, either alone or in combination with chemotherapy. Effectiveness of treatment was assessed by the enumeration of CFUs in the spleens and lungs, together with other indicators. RESULTS: Multiplication of M. tuberculosis was reduced by IL-12 in a dose-dependent manner if the treatment began at day 1, whereas no statistically significant suppression was observed if the treatment began at day 14. Combination with IL-12 did not enhance the bactericidal activity of antituberculosis chemotherapy. The growth curves of MAC in IL-12-treated mice were almost identical to those of untreated controls, indicating that IL-12 did not affect the multiplication of MAC in beige mice. In both experiments, the dosing of IL-12 approached levels of severe toxicity for the mouse strains used. CONCLUSIONS: IL-12 had a positive affect on early multiplication of M. tuberculosis. It had no effect on early multiplication of M. avium complex.

Mycobacterium avium complex common-source or cross-infection in AIDS patients attending the same day-care facility

To delineate the epidemiology of Mycobacterium avium complex (MAC) infection in acquired immunodeficiency syndrome patients, we studied 32 case patients with disseminated MAC infection who attended the same daycare facility during a period of 13 months. Pulsed-field gel electrophoresis analysis showed very low similarity between MAC strains, suggesting that, despite close contacts between the patients, nosocomial cross-transmission or exposure to a common source of MAC did not occur.

In vitro and in vivo activities of moxifloxacin and clinafloxacin against Mycobacterium tuberculosis

On 10% oleic acid-albumin-dextrose-catalase-enriched 7H11 agar medium, the MIC at which 90% of the isolates are inhibited for 20 strains of Mycobacterium tuberculosis was 0.5 microg of sparfloxacin (SPFX) or moxifloxacin (MXFX) per ml and 1.0 microg of clinafloxacin (CNFX) per ml, indicating that the in vitro activities of SPFX and MXFX were virtually identical and were slightly greater than that of CNFX. However, the in vivo activities of these drugs in a murine tuberculosis model differed considerably. Female Swiss mice were infected intravenously with 6.2 x 10(6) CFU of the H37Rv strain and treated for 4 weeks, beginning the next day after infection, with isoniazid (INH) serving as the positive control. By the criteria of 30-day survival rate, spleen weight, gross lung lesion, and mean number of CFU in the spleen, treatment with CNFX at up to 100 mg/kg of body weight six times weekly displayed no measurable effect against M. tuberculosis, whereas both SPFX and MXFX were effective; administration six times weekly of either of the latter two drugs demonstrated dosage-dependent bactericidal effects, as measured by enumeration of CFU in the spleens, and MXFX appeared more bactericidal than the same dosage of SPFX. Of the three fluoroquinolones, only MXFX at 100 mg/kg six times weekly appeared as bactericidal as INH at 25 mg/kg six times weekly. Thus, MXFX may be an important component of the newer combined regimens for treatment of tuberculosis.

Use of DNA fingerprinting for primary surveillance of nosocomial tuberculosis in a large urban hospital: detection of outbreaks in homeless people and migrant workers

SETTING

A large urban teaching hospital in the southeast of Paris.

OBJECTIVE

Primary surveillance of nosocomial transmission of tuberculosis (TB) by systematic restriction fragment length polymorphism analysis (RFLP) of isolates (n = 161) recovered from smear-positive pulmonary TB patients identified from 1 March 1993 to 28 February 1994, and from all TB patients (with any form of tuberculous infection) identified from 1 March 1994 to 30 April 1995.

RESULTS

Systematic RFLP analysis revealed 12 clusters of patients (n = 40) infected by strains of Mycobacterium tuberculosis showing matching RFLP patterns. None of the isolates were multidrug-resistant. Compared with non-clustered patients, clustered patients were more likely to be homeless (55% vs 19%, P < or = 0.001), or Africans living in hostels for migrant workers (20% vs 6%, P = 0.01), and had fewer previous admissions to hospital (12% vs 28%, P = 0.05). Further epidemiological investigations showed that the clustered TB cases actually resulted not from nosocomial transmission, but from transmission in the community, very likely in homeless shelters and hostels for migrant workers.

CONCLUSION

No nosocomial transmission of TB was identified among the patients included during the study period. Systematic RFLP analysis using hospital-based sampling can detect the spread of TB in specific environments in the community where transmission is occurring.

Once-weekly rifapentine-containing regimens for treatment of tuberculosis in mice

The bactericidal activities of several once-weekly rifapentine (P)-containing combination regimens against Mycobacterium tuberculosis, and their ability to prevent the selection of rifampin (R)-resistant mutants, were compared with those of the standard six-times-weekly regimen consisting of R, isoniazid (H), and pyrazinamide (Z) in a mouse experiment. Mice were infected intravenously with 1.3 x 10(7) cfu of M. tuberculosis strain H37Rv, and 8 wk of treatment began on Day 14 after infection, when mice were randomly allocated to an untreated control group and nine treatment groups of 30 mice each. At the end of 8 wk of treatment, all the tested regimens showed promising bactericidal activities. Once-weekly P alone was less bactericidal than six-times-weekly R alone; likewise, the once-weekly P-containing combined regimens were less bactericidal than the six-times-weekly standard regimen. However, the difference in killing was about 1 log10, which represented only a fraction of the overall 4 log10 to 5 log10 magnitude of killing effects. The addition of streptomycin (S) improved the bactericidal effect of once-weekly PHZ, and the effect of once-weekly PHZS was further enhanced when it was preceded by 2 wk of daily HZS. The latter regimen achieved the same level of activity as the standard six-times-weekly regimen. All of the once-weekly P-containing combined regimens were able to prevent the selection of R-resistant mutants, whereas monotherapy with R or P selected resistant mutants in approximately 50% of animals.