Outcomes of patients with multidrug-resistant pulmonary tuberculosis treated with ofloxacin/levofloxacin-containing regimens

Management of multidrug-resistant tuberculosis: Update 2007

Multidrug-resistant tuberculosis (MDR-TB) with bacillary resistance to at least isoniazid and rifampicin in vitro is a worldwide phenomenon. Hot spots of the disease are found scattered in different continents. Prevention of its development through good tuberculosis control programmes operating under the directly observed therapy, short-course (DOTS) strategy is of paramount importance. However, with established MDR-TB, treatment with alternative and specific chemotherapy is necessary to achieve a beneficial outcome. Such an approach on a programme basis is currently known as the 'DOTS-Plus' strategy. Second-line (reserve) drugs utilized in the treatment of MDR-TB are generally less potent and more toxic, perhaps with the notable exceptions of some fluoroquinolones and injectable agents. Surgery has a distinct adjunctive role for the management of MDR-TB in selected patients. The emergence of extensively drug-resistant tuberculosis (XDR-TB), that is, MDR-TB with additional bacillary resistance to the fluoroquinolones and injectables, has provided a very alarming challenge to global health, as the disease currently has a low cure rate and high mortality. In order to combat XDR-TB, strengthening of DOTS and DOTS-Plus programmes is mandatory, especially in the face of surging HIV infection. Furthermore, more attention needs to be focused on developing new drugs with potent bactericidal and sterilizing activities and low side-effects, and above all, drugs that are affordable for communities worldwide.

Fluoroquinolones for treating tuberculosis

BACKGROUND

Fluoroquinolones are sometimes used to treat multiple-drug-resistant and drug-sensitive tuberculosis. The effects of fluoroquinolones in tuberculosis regimens need to be assessed.

OBJECTIVES

To assess fluoroquinolones as additional or substitute components to antituberculous drug regimens for drug-sensitive and drug-resistant tuberculosis.

SEARCH STRATEGY

In July 2007, we searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (The Cochrane Library 2007, Issue 3), MEDLINE, EMBASE, LILACS, Science Citation Index, Database of Russian Publications, and metaRegister of Controlled Trials. We also scanned reference lists of all identified studies and contacted researchers.

SELECTION CRITERIA

Randomized controlled trials of antituberculous regimens containing fluoroquinolones in people diagnosed with bacteriologically positive (sputum smear or culture) pulmonary tuberculosis.

DATA COLLECTION AND ANALYSIS

Two authors independently applied inclusion criteria, assessed methodological quality, and extracted data. We used relative risk (RR) for dichotomous data, weighted mean difference (WMD) for continuous data (both with 95% confidence intervals (CI)), and the random-effects model if we detected heterogeneity and it was appropriate to combine data.

MAIN RESULTS

Eleven trials (1514 participants) met the inclusion criteria. No statistically significant difference was found in trials substituting ciprofloxacin, ofloxacin or moxifloxacin for first-line drugs in relation to cure (416 participants, 3 trials), treatment failure (388 participants, 3 trials), or clinical or radiological improvement (216 participants, 2 trials). Substituting ciprofloxacin into first-line regimens in drug-sensitive tuberculosis led to a higher incidence of relapse (RR 7.17, 95% CI 1.33 to 38.58; 384 participants, 3 trials) and longer time to sputum culture conversion (WMD 0.50 months, 95% CI 0.18 to 0.82; 168 participants, 1 trial), although this was confined to HIV-positive participants. Substituting for ethambutol in first-line regimens led to a higher incidence of total number of adverse events (RR 1.34, 95% CI 1.05 to 1.72; 492 participants, 2 trials). Adding or substituting levofloxacin to basic regimens in drug-resistant areas had no effect. A comparison of sparfloxacin versus ofloxacin added to regimens showed no statistically significant difference in cure (184 participants, 2 trials), treatment failure (149 participants, 2 trials), or the total number of adverse events (253 participants, 3 trials).

AUTHORS' CONCLUSIONS

Only ciprofloxacin, ofloxacin, levofloxacin, sparfloxacin and moxifloxacin have been tested in randomized controlled trials for treating tuberculosis. We cannot recommend ciprofloxacin in treating tuberculosis. Trials of newer fluoroquinolones for treating tuberculosis are needed and are on-going. No difference has been demonstrated between sparfloxacin and ofloxacin in drug-resistant tuberculosis.

In vivo validation of the mutant selection window hypothesis with moxifloxacin in a murine model of tuberculosis

Combination therapy is the most effective strategy to prevent emergence of resistance during tuberculosis (TB) treatment. Another strategy, albeit theoretical, is to limit the time that drug concentrations fall in the "mutant selection window" (MSW) between the MIC and the mutant prevention concentration (MPC). Drug concentrations above the MPC prevent selective amplification of resistant mutants in vitro even with a single drug exposure. The MSW concept has been validated using fluoroquinolones against Mycobacterium tuberculosis in vitro but not in vivo. Using a mouse model in which serum moxifloxacin (MXF) concentrations were maintained above the MPC, we tested whether this strategy prevents selection of MXF-resistant mutants. Beginning 2 weeks after aerosol infection with M. tuberculosis, when the mean lung log(10) CFU count was 7.9 +/- 0.2, mice received either no treatment or MXF in the diet at 0.25% to approximate the conventional human dose or 1.5% to maintain serum concentrations above the MPC (8 microg/ml). After 56 days of treatment, lung CFU counts were 3.5 +/- 0.8 and 0.9 +/- 0.6 in 0.25% and 1.5% of the MXF-treated mice, respectively. In mice given 0.25% MXF, MXF-resistant mutants were selected by day 28 and detected in 16% (3/19) of mice tested on day 56. No selection of MXF-resistant mutants was detected in mice given 1.5% MXF. We conclude that maintaining serum concentrations of MXF above the MPC prevents selection of MXF-resistant mutants. Although this target cannot be achieved clinically with MXF, it might be possible with new fluoroquinolones with more potent activity and/or improved pharmacokinetics.

Impact of extensive drug resistance on treatment outcomes in non-HIV-infected patients with multidrug-resistant tuberculosis

BACKGROUND

Recently, serious concerns about extensively drug-resistant tuberculosis (XDR-TB), which shows resistance to second-line anti-TB drugs in addition to isoniazid and rifampicin, have been raised. The aim of this study was to elucidate the impact of extensive drug resistance on treatment outcomes in non-human immunodeficiency virus (HIV)-infected patients with multidrug-resistant tuberculosis (MDR-TB).

METHODS

Patients who received the diagnosis of and treatment as having MDR-TB at Seoul National University Hospital (Seoul, Republic of Korea) between January 1996 and December 2005 were included. The definition of XDR-TB was TB caused by bacilli showing resistance to both isoniazid and rifampicin and also showing resistance to any fluoroquinolone and to at least 1 of the following 3 injectable anti-TB drugs: capreomycin, kanamycin, and amikacin. To identify the impact of extensive drug resistance on treatment outcomes, univariate comparison and multiple logistic regression were performed.

RESULTS

A total of 211 non-HIV-infected patients with MDR-TB were included in the final analysis. Among them, 43 patients (20.4%) had XDR-TB. Treatment failure was observed in 19 patients (44.2%) with XDR-TB, whereas treatment of 46 patients (27.4%) with non-XDR-TB failed (P=.057). The presence of extensive drug resistance (adjusted odds ratio [OR], 4.46; 95% confidence interval [CI], 1.35-14.74) and underlying comorbidity (adjusted OR, 2.62; 95% CI, 1.00-6.87) were independent risk factors for treatment failure. However, a higher level of albumin was inversely associated with treatment failure (adjusted OR, 0.87; 95% CI, 0.77-0.97).

CONCLUSION

The presence of extensive drug resistance, the presence of comorbidity, and hypoalbuminemia were independent poor prognostic factors in non-HIV-infected patients with MDR-TB.

HIV infection and multidrug-resistant tuberculosis: the perfect storm

BACKGROUND

Multidrug-resistant (MDR) tuberculosis (TB) has emerged as a global epidemic, with ~425,000 new cases estimated to occur annually. The global human immunodeficiency virus (HIV) infection epidemic has caused explosive increases in TB incidence and may be contributing to increases in MDR-TB prevalence.

METHODS

We reviewed published studies and available surveillance data evaluating links between HIV infection and MDR-TB to quantify convergence of these 2 epidemics, evaluate the consequences, and determine essential steps to address these epidemics.

RESULTS

Institutional outbreaks of MDR-TB have primarily affected HIV-infected persons. Delayed diagnosis, inadequate initial treatment, and prolonged infectiousness led to extraordinary attack rates and case-fatality rates among HIV-infected persons. Whether this sequence occurs in communities is less clear. MDR-TB appears not to cause infection or disease more readily than drug-susceptible TB in HIV-infected persons. HIV infection may lead to malabsorption of anti-TB drugs and acquired rifamycin resistance. HIV-infected patients with MDR-TB have unacceptably high mortality; both antiretroviral and antimycobacterial treatment are necessary. Simultaneous treatment requires 6-10 different drugs. In HIV-prevalent countries, TB programs struggle with increased caseloads, which increase the risk of acquired MDR-TB. Surveillance data suggest that HIV infection and MDR-TB may converge in several countries.

CONCLUSIONS

Institutional outbreaks, overwhelmed public health programs, and complex clinical management issues may contribute to the convergence of the MDR-TB and HIV infection epidemics. To forestall disastrous consequences, infection control, rapid case detection, effective treatment, and expanded program capacity are needed urgently.

Chemotherapy and diagnosis of tuberculosis

Since after the first streptomycin 1944 trials, anti-tuberculous chemotherapy research has been focused upon establishing drug combination regimens capable of overcoming drug resistance and amenable to ambulatory treatment in resource strapped countries. The first milestone being the 1959 Madras trial comparing home and sanatorium treatment in South India. Subsequently, the MRC trials led Fox and Mitchison to indicate rifampicin, isoniazid and pyrazinamide as the first line drugs for short course, 6 month, regimens and the 1982 Hong Kong Chest Service trials established intermittent therapy as the ambulatory treatment standard for directly observed therapy (DOT). The rising of the HIV epidemic at the beginning of the 1980s has refuelled tuberculosis spread in Africa and Asia and contributed to the expansion of drug-resistant tuberculosis worldwide making the development of new drugs and drug regimens for ambulatory treatment a top priority. Led by biotechnological advances, molecular biology has been brought into TB laboratory diagnosis for the highly sensitive and specific rapid identification of Mycobacterium tuberculosis in biological samples. The field of immunological diagnosis of TB infection, dominated since the early 1900s by the intradermal tuberculin reaction has been put back in motion by the discovery of M. tuberculosis-specific proteins and peptides, now employed in blood tests of high sensitivity and specificity for the diagnosis of latent TB which may help with the identification of contacts at higher risk of active disease and the eradication of epidemic cases.

Key issues in multidrug-resistant tuberculosis

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

Fluoroquinolones for the Treatment of Pulmonary Tuberculosis

Tuberculosis (TB) continues to be a significant problem globally. Treatment includes a multiple drug regimen with isoniazid, rifampicin (rifampin), pyrazinamide and ethambutol. Often, one of these medications needs to be replaced as a result of adverse events or because Mycobacterium tuberculosis develops resistance against one these first-line agents. Fluoroquinolones, particularly the newer ones, possess good in vitro (levofloxacin, gatifloxacin, moxifloxacin) and in vivo (gatifloxacin and moxifloxacin) bactericidal activity against M. tuberculosis, making them attractive agents for the treatment of pulmonary TB. All relevant clinical trials, cohort studies and case reports investigating the clinical efficacy and tolerability of fluoroquinolones when used for the treatment of pulmonary TB were evaluated for this review. Specifically, efficacy and safety in the following indications were investigated: (i) first-line treatment of drug-sensitive pulmonary TB; (ii) first-line treatment for multi-drug resistant (MDR) TB; and (iii) treatment of patients with drug intolerance. Twenty-seven articles met our inclusion criteria; nine articles presented data from randomised, controlled or cohort studies. Seven studies used fluoroquinolones as first-line agents in drug-sensitive TB (1469 patients), 15 studies used fluoroquinolones to treat MDR-TB (1025 patients) and six studies (951 patients) investigated the use of fluoroquinolones in patients intolerant to other TB medications. In patients with susceptible M. tuberculosis strains, substitution with a fluoroquinolone did not have an effect on cure or radiological improvement at 8 weeks or failure at 12 months. Substitution of older fluoroquinolones into a regimen, especially ciprofloxacin, resulted in a higher rate of relapse and a longer time to sputum-culture conversions. The use of fluoroquinolones in patients with MDR-TB is supported by some trials where others show a lack of improvement in efficacy of a regimen. Our review of the literature does not support the use of older fluoroquinolones, especially ciprofloxacin, as substitute agents for drug-sensitive or drug-resistant TB. However, newer fluoroquinolones, such as moxifloxacin, may be a reasonable alternative based on results from one large clinical trial. Fluoroquinolones have an important role as substitute agents for those who are intolerant of first-line TB agents.

The ever-expanding association between rheumatologic diseases and tuberculosis

We summarized most of the rheumatologic manifestations of tuberculosis (TB) and the occurrence of Mycobacterium tuberculosis disease associated with rheumatologic diseases. We established 4 different categories: (1) direct musculoskeletal involvement of M. tuberculosis, including spondylitis, osteomyelitis, septic arthritis, and tenosynovitis; (2) M. tuberculosis as an infectious pathogen in rheumatologic diseases, particularly with the use of newer agents such as tumor necrosis factor-alpha inhibitors; (3) antimycobacterial drug-induced rheumatologic syndromes, including tendinopathy, drug-induced lupus, and others; and (4) reactive immunologic phenomena caused by TB, such as reactive arthritis, erythema nodosum, and others. In addition, Bacille-Calmette-Guérin vaccination used for the prevention of TB or as a chemotherapeutic agent for bladder carcinoma also may be associated with musculoskeletal adverse events. We conclude that M. tuberculosis can directly or indirectly affect the musculoskeletal system.

Community-based therapy for children with multidrug-resistant tuberculosis

OBJECTIVES

The goals were to describe the management of multidrug-resistant tuberculosis among children, to examine the tolerability of second-line antituberculosis agents among children, and to report the outcomes of children treated for multidrug-resistant tuberculosis in poor urban communities in Lima, Peru, a city with high tuberculosis prevalence.

METHODS

A retrospective analysis of data for 38 children <15 years of age with multidrug-resistant tuberculosis, either documented with drug sensitivity testing of the child's tuberculosis isolate or suspected on the basis of the presence of clinical symptoms for a child with a household contact with documented multidrug-resistant tuberculosis, was performed. All 38 children initiated a supervised individualized treatment regimen for multidrug-resistant tuberculosis between July 1999 and July 2003. Each child received 18 to 24 months of therapy with > or =5 first- or second-line drugs to which their Mycobacterium tuberculosis strain was presumed to be sensitive.

RESULTS

Forty-five percent of the children had malnutrition or anemia at the time of diagnosis, 29% had severe radiographic findings (defined as bilateral or cavitary disease), and 13% had extrapulmonary disease. Forty-five percent of the children were hospitalized initially because of the severity of illness. Adverse events were observed for 42% of the children, but no events required suspension of therapy for >5 days. Ninety-five percent of the children (36 of 38 children) achieved cures or probable cures, 1 child (2.5%) died, and 1 child (2.5%) defaulted from therapy.

CONCLUSIONS

Multidrug-resistant tuberculosis disease among children can be treated successfully in resource-poor settings. Treatment is well tolerated by children, and severe adverse events with second-line agents are rare.

Moxifloxacin versus ethambutol in the first 2 months of treatment for pulmonary tuberculosis

RATIONALE

Moxifloxacin has promising preclinical activity against Mycobacterium tuberculosis, but has not been evaluated in multidrug treatment of tuberculosis in humans.

OBJECTIVE

To compare the impact of moxifloxacin versus ethambutol, both in combination with isoniazid, rifampin, and pyrazinamide, on sputum culture conversion at 2 mo as a measure of the potential sterilizing activity of alternate induction regimens.

METHODS

Adults with smear-positive pulmonary tuberculosis were randomized in a factorial design to receive moxifloxacin (400 mg) versus ethambutol given 5 d/wk versus 3 d/wk (after 2 wk of daily therapy). All doses were directly observed.

MEASUREMENTS

The primary endpoint was sputum culture status at 2 mo of treatment.

RESULTS

Of 336 patients enrolled, 277 (82%) were eligible for the efficacy analysis, 186 (67%) were male, 175 (63%) were enrolled at African sites, 206 (74%) had cavitation on chest radiograph, and 60 (22%) had HIV infection. Two-month cultures were negative in 71% of patients (99 of 139) treated with moxifloxacin versus 71% (98 of 138) treated with ethambutol (p = 0.97). Patients receiving moxifloxacin, however, more often had negative cultures after 4 wk of treatment. Patients treated with moxifloxacin more often reported nausea (22 vs. 9%, p = 0.002), but similar proportions completed study treatment (88 vs. 89%). Dosing frequency had little effect on 2-mo culture status or tolerability of therapy.

CONCLUSIONS

The addition of moxifloxacin to isoniazid, rifampin, and pyrazinamide did not affect 2-mo sputum culture status but did show increased activity at earlier time points.

Stepwise Decrease in Moxifloxacin Susceptibility amongst Clinical Isolates of Multidrug-ResistantMycobacterium tuberculosis:Correlation with Ofloxacin Susceptibility

To study the effectiveness of moxifloxacin (MOX) against multidrug-resistant (MDR) Mycobacterium tuberculosis (MTB), in vitro drug susceptibility tests on MOX and ofloxacin (OFX) using the MGIT system against 132 nonduplicate MDR MTB isolates (108 OFX-sensitive and 24 OFX-resistant) were performed. Eleven OFX-resistant non-MDR MTB isolates were also included. All strains that were susceptible to OFX were shown to be also susceptible to MOX. For OFX-resistant isolates, regardless of their MDR status, a 4- to 8-fold decrease in MIC was observed for MOX when compared to OFX. On the basis of similarities in mode of action and pharmacokinetic data between MOX and OFX, a breakpoint MIC of 2 mg/L was suggested for MOX in the MGIT system. All but two OFX-resistant isolates possessed MIC of MOX of 2 mg/L or lower and were considered to be susceptible to MOX; however, all OFX-resistant strains studied had mutations involved in resistance to quinolones. DNA sequence analysis for the gyrase A mutation, which was an indicator for OFX resistance, correlated with MOX susceptibility changes. Significant decreases in MOX susceptibility amongst MDR-MTB strains were observed that correlated with OFX susceptibility. The Asp94Gly mutation appeared to be associated with a higher level of MICs to both OFX and MOX. These findings on the stepwise decline of in vitro susceptibility to MOX suggest that clinical usage of MOX should be accompanied by careful monitoring of susceptibility to this important anti-MDR MTB drug.

Treatment of multiple drug-resistant tuberculosis (MDR-TB) in Iran

SETTING

Masih Daneshvari Hospital, Tehran, Iran, 2000-2002.

OBJECTIVE

To evaluate the effectiveness of multiple drug-resistant tuberculosis (MDR-TB) treatment for the first time in Iran.

DESIGN

All cases of MDR-TB with complete follow-up data were recruited and results of their treatments were evaluated.

RESULTS

MDR-TB treatment was initiated with 5.23 drugs, on average. Isoniazid, amikacin, and ofloxacin were present in the drug regimen of all patients. Average duration of the treatment was 18.5 months (range, 7-36). Over 76% of the patients responded to the treatment (negative smear and culture). Cure and probable cure were documented in seven (41.2%) and four (23.5%) of the patients, respectively. No failure in the treatment occurred when cycloserine was present in the treatment regimen.

CONCLUSION

A majority of the MDR-TB patients in Iran can be cured with the use of appropriate treatment regimens. An even greater success could be achieved by providing more second-line drugs.

Imipenem for treatment of tuberculosis in mice and humans

Chemotherapy of tuberculosis caused by multiple-drug-resistant (MDR) strains is problematic because of choices limited to relatively inefficacious and toxic drugs. Some beta-lactam antibiotics are active against Mycobacterium tuberculosis in vitro. We investigated the efficacy of imipenem in a mouse model of tuberculosis and in humans with MDR tuberculosis. Mice infected with M. tuberculosis strain H37Rv were treated with isoniazid or imipenem. Residual organisms in lung and spleen and survival of imipenem-treated mice were compared to those of untreated or isoniazid-treated mice. Ten patients with MDR tuberculosis also were treated with imipenem in combination with other first- or second-line agents; elimination of M. tuberculosis from sputum samples was measured by quantitative culture. Although it was less effective than isoniazid, imipenem significantly reduced the numbers of M. tuberculosis organisms in lungs and spleens and improved survival of mice. Eight of 10 patients with numerous risk factors for poor outcomes responded to imipenem combination therapy with conversion of cultures to negative. Seven remained culture-negative off of therapy. There were two deaths, one of which was due to active tuberculosis. Organisms were eliminated from the sputa of responders at a rate of 0.35 log10 CFU/ml/week. Relapse upon withdrawal of imipenem and development of resistance to imipenem in a nonresponder suggest that imipenem exerts antimycobacterial activity in humans infected with M. tuberculosis. Imipenem had antimycobacterial activity both in a mouse model and in humans at high risk for failure of treatment for MDR tuberculosis.

Fluoroquinolones for treating tuberculosis

BACKGROUND

Fluoroquinolones are sometimes used to treat multiple-drug-resistant and drug-sensitive tuberculosis. The effects of fluoroquinolones in tuberculosis regimens need to be assessed.

OBJECTIVES

To assess fluoroquinolones as additional or substitute components to antituberculous drug regimens for drug-sensitive and drug-resistant tuberculosis.

SEARCH STRATEGY

We searched the Cochrane Infectious Diseases Group Specialized Register (April 2005), CENTRAL (The Cochrane Library Issue 1, 2005), MEDLINE (1966 to April 2005), EMBASE (1974 to April 2005), LILACS (1982 to April 2005), Science Citation Index (1940 to April 2005), and Russian database (1988 to April 2005). We also scanned reference lists of all identified studies and contacted researchers.

SELECTION CRITERIA

Randomized controlled trials of antituberculous regimens containing fluoroquinolones in people diagnosed with bacteriologically positive (sputum smear or culture) pulmonary tuberculosis.

DATA COLLECTION AND ANALYSIS

Two authors independently applied inclusion criteria, assessed methodological quality, and extracted data. We used relative risk (RR) for dichotomous data, weighted mean difference (WMD) for continuous data (both with 95% confidence intervals (CI)), and the random-effects model if we detected heterogeneity and appropriate to combine data.

MAIN RESULTS

Ten trials (1178 participants) met the inclusion criteria. No statistically significant difference was found in trials substituting ciprofloxacin or ofloxacin for first-line drugs in relation to cure (89 participants, 2 trials), treatment failure (388 participants, 3 trials), or clinical or radiological improvement (216 participants, 2 trials). Substituting ciprofloxacin into first-line regimens in drug-sensitive tuberculosis led to a higher incidence of relapse (RR 7.17, 95% CI 1.33 to 38.58; 384 participants, 3 trials) and longer time to sputum culture conversion (WMD 0.50 months, 95% CI 0.18 to 0.82; 168 participants, 1 trial), although this was confined to HIV-positive participants. Adding or substituting levofloxacin to basic regimens in drug-resistant areas had no effect. A comparison of sparfloxacin versus ofloxacin added to regimens showed no statistically significant difference in cure (184 participants, 2 trials), treatment failure (149 participants, 2 trials), or total number of adverse events (253 participants, 3 trials).

AUTHORS' CONCLUSIONS

Only ciprofloxacin, ofloxacin, levofloxacin, and sparfloxacin have been tested in randomized controlled trials for treating tuberculosis. We cannot recommend ciprofloxacin in treating tuberculosis. Trials of newer fluoroquinolones for treating tuberculosis are needed. No difference has been demonstrated between sparfloxacin and ofloxacin in drug-resistant tuberculosis.

Treatment of multidrug-resistant tuberculosis in San Francisco: an outpatient-based approach

BACKGROUND

Treatment of patients with multidrug-resistant tuberculosis requires prolonged therapy, often involving long hospital stays. Despite intensive and costly therapy, cure rates are relatively low.

METHODS

We reviewed the outcomes for all patients with multidrug-resistant tuberculosis treated in San Francisco, California, during 1982-2000 and identified billing charges for patients treated during 1995-2000. Mycobacterium tuberculosis isolates were genotyped by IS6110-based restriction fragment-length polymorphism analysis.

RESULTS

Forty-eight cases were identified with resistance to a median of 3 drugs (range, 2-9 drugs). The median age of the patients was 49.5 years (range, 22-78 years); 36 (75%) of 48 patients were foreign born, 11 (23%) were human immunodeficiency virus (HIV) seropositive, and 45 (94%) had pulmonary tuberculosis. Thirty-two (97%) of the 33 HIV-seronegative patients were cured, with only 1 relapse occurring 5 years after treatment. All 11 HIV-seropositive patients died during observation. Twenty-one patients (44%) required hospitalization, with a median duration of stay of 14 days (range, 3-74 days). The estimated inpatient and outpatient aggregate cost for the 11 patients treated after 1994 was $519,928, with a median cost of $27,752 per patient. No secondary cases of multidrug-resistant tuberculosis were identified through population-based genotyping.

CONCLUSIONS

Treatment of multidrug-resistant tuberculosis in HIV-seronegative patients largely on an outpatient basis was feasible and was associated with high cure rates and lower cost than in other published studies. Patients with underlying HIV infection had very poor outcomes.

Fluoroquinolone Susceptibility among Mycobacterium tuberculosis Isolates from the United States and Canada

BACKGROUND

There is increasing interest in the possible role of new fluoroquinolone antibiotics for treatment of tuberculosis, but widespread use of fluoroquinolones for treatment of other bacterial infections may select for resistant strains of Mycobacterium tuberculosis.

METHODS

We evaluated fluoroquinolone susceptibility using the proportion method (critical ciprofloxacin concentration for susceptibility testing, 2.0 mu g/mL) in isolates obtained from patients enrolled in Tuberculosis Trial Consortium clinical trials during the period of 1995-2001 and in a referral sample of isolates sent to the Centers for Disease Control and Prevention (Atlanta, GA) during the period of 1996-2000 for additional testing, often because of drug resistance.

RESULTS

Of the 1373 isolates from the clinical trials, 1324 (96%) were susceptible to isoniazid and rifampin; 2 (0.15%) of these isolates were also resistant to ciprofloxacin. Of the 1852 isolates from the referral sample, 603 (32.6%) were resistant to isoniazid and rifampin (i.e., multidrug resistant), 849 (45.7%) were resistant to >or=1 first-line drug but were not resistant to both isoniazid and rifampin, and 400 (21.6%) were susceptible to all first-line agents. Ciprofloxacin resistance was found in 33 (1.8%) of the referral-sample isolates. Most ciprofloxacin-resistant isolates (25 [75.8%]) were resistant to isoniazid and rifampin.

CONCLUSIONS

Despite widespread use of fluoroquinolones for treatment of common bacterial infections, resistance among clinical isolates of M. tuberculosis in the United States and Canada remains rare, occurring primarily among multidrug-resistant strains.

Clinical outcome of individualised treatment of multidrug-resistant tuberculosis in Latvia: a retrospective cohort study

BACKGROUND

Latvia has one of the highest rates of multidrug-resistant tuberculosis (MDRTB). Our aim was to assess treatment outcomes for the first full cohort of MDRTB patients treated under Latvia's DOTS-Plus strategy following WHO guidelines.

METHODS

We retrospectively reviewed all civilian patients who began treatment with individualised treatment regimens for pulmonary MDRTB in Latvia between Jan 1, and Dec 31, 2000. We applied treatment outcome definitions for MDRTB, developed by an international expert consensus group, and assessed treatment effectiveness and risk factors associated with poor outcome.

FINDINGS

Of the 204 patients assessed, 55 (27%) had been newly diagnosed with MDRTB, and 149 (73%) had earlier been treated with first-line or second-line drugs for this disease. Assessment of treatment outcomes showed that 135 (66%) patients were cured or completed therapy, 14 (7%) died, 26 (13%) defaulted, and treatment failed in 29 (14%). Of the 178 adherent patients, 135 (76%) achieved cure or treatment completion. In a multivariate Cox proportional-hazards model of these patients, independent predictors of poor outcome (death and treatment failure) included having previously received treatment for MDRTB (hazard ratio 5.7, 95% CI 1.9-16.6), the use of five or fewer drugs for 3 months or more (3.2, 1.1-9.6), resistance to ofloxacin (2.6, 1.2-5.4), and body-mass index less than 18.5 at start of treatment (2.3, 1.1-4.9).

INTERPRETATION

The DOTS-Plus strategy of identifying and treating patients with MDRTB can be effectively implemented on a nationwide scale in a setting of limited resources.

Action of fluoroquinolones and Linezolid on logarithmic- and stationary-phase culture of Mycobacterium tuberculosis

BACKGROUND

The new challenges involved in the chemotherapy of tuberculosis make it necessary to find novel drugs, especially ones that are useful in the latent phase of the disease.

METHODS

We evaluated the activity of linezolid and fluoroquinolones against logarithmic- and stationary-phase Mycobacterium tuberculosis.

RESULTS

We observed that linezolid exhibits antibacterial action, although slowly, in both situations. Quinolones with an 8-methoxy group exhibit greater activity than levofloxacin in logarithmic growth phases, whereas levofloxacin exhibits greater activity in stationary-phase growth.

CONCLUSION

The study of the activity of drugs against the M. tuberculosis microorganism in the latent phase is one of the most important tools available in the fight against the tuberculosis epidemic, and both linezolid and the new fluoroquinolones appear to be promising drugs.

Which agents should we use for the treatment of multidrug-resistant Mycobacterium tuberculosis?

The inappropriate treatment of drug-susceptible tuberculosis can lead to the selection and transmission of multidrug-resistant tuberculosis (MDR-TB), indicating resistance to at least isoniazid and rifampicin. In the treatment of MDR-TB, residual first-line drugs, such as ethambutol, pyrazinamide and streptomycin must be appropriately combined with additional second-line drugs, guided by individual susceptibility patterns. The clinical pharmacology of these second-line antituberculous drugs is reviewed. Fluoroquinolones represent the only substantial therapeutic advance in the last 20 years. Many factors potentially affect the outcome of MDR-TB. Treatment adherence, prior exposure to antituberculous drugs, the number of drugs to which the infection is still susceptible and the time since the first diagnosis of tuberculosis are the most relevant. The management of MDR-TB requires considerable expertise. When initiating or revising therapy for MDR-TB, the process of selecting drugs should rely on prior treatment history, results of susceptibility testing and an evaluation of the patient's adherence. In making drug selection, we propose to follow a hierarchy based on the intrinsic activity against Mycobacterium tuberculosis and the clinical evidence of efficacy of the available active compounds.

Treatment and Outcome Analysis of 205 Patients with Multidrug-resistant Tuberculosis

Multidrug-resistant tuberculosis, a disease caused by Mycobacterium tuberculosis strains that are resistant at least to rifampin and isoniazid, entails extended treatment, expensive and toxic regimens, and higher rates of treatment failure and death. We retrospectively analyzed the outcomes in 205 patients treated at our center for multidrug-resistant tuberculosis, with strains resistant to a median of six drugs, and compared the results with those of our previous series. Logistic regression and survival analysis were used to evaluate short- and long-term outcomes, respectively. Initial favorable response, defined as at least three consecutive negative sputum cultures over a period of at least 3 months, was 85% compared with 65% in the prior cohort. The current cohort had greater long-term success rates, 75% versus 56%, and lower tuberculosis death rates, 12% versus 22%, than the earlier one. Surgical resection and fluoroquinolone therapy were associated with improved microbiological and clinical outcomes in the 205 patients studied after adjusting for other variables. The improvement was statistically significant for surgery and among older patients for fluoroquinolone therapy.

Multiplex PCR amplimer conformation analysis for rapid detection of gyrA mutations in fluoroquinolone-resistant Mycobacterium tuberculosis clinical isolates

A new strategy known as multiplex PCR amplimer conformation was developed for detection of mutation in the gyrA gene of 138 clinical isolates of Mycobacterium tuberculosis. The method generated a single-stranded and heteroduplex DNA banding pattern of multiplex PCR amplimers of the region of interest that was extremely sensitive to specific mutations, thus enabling much more sensitive and reliable mutation analysis compared to the standard single-stranded conformation polymorphism technique. The genetic profiles of the gyrA gene of the 138 isolates as detected by MPAC were confirmed by nucleotide sequencing and were found to correlate strongly with the in vitro susceptibilities of the mutant strains to six fluoroquinolones (ofloxacin, levofloxacin, sparfloxacin, moxifloxacin, gatifloxacin, and sitafloxacin). All 32 isolates that contained gyrA mutations exhibited cross-resistance to the six fluoroquinolones (ofloxacin MIC for 90% of strains > 16 mg/liter), although moxifloxacin, gatifloxacin, and sitafloxacin (MIC for 90% of strains </= 4 mg/liter) were apparently more active than ofloxacin, levofloxacin, and sparfloxacin (MIC for 90% of strains >/==" BORDER="0"> 16 mg/liter). All gyrA mutations were clustered in codons 90, 91, and 94, and aspartic acid 94 was most frequently mutated. Twenty-three isolates without gyrA mutations were also found to exhibit reduced susceptibility to ofloxacin (MIC for 90% of strains = 4 mg/liter), but largely remained susceptible to other drugs (MIC for 90% of strains </= 1 mg/liter). Another 83 isolates without mutations were fully susceptible to all six fluoroquinolones (ofloxacin MIC for 90% of strains = 1 mg/liter). In conclusion, high-level phenotypic resistance to fluoroquinolones among M. tuberculosis clinical isolates, which appears to be predominantly due to gyrA mutations, may be readily detected by genotyping techniques such as multiplex PCR amplimer conformation.

Programmes and principles in treatment of multidrug-resistant tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) presents an increasing threat to global tuberculosis control. Many crucial management issues in MDR-TB treatment remain unanswered. We reviewed the existing scientific research on MDR-TB treatment, which consists entirely of retrospective cohort studies. Although direct comparisons of these studies are impossible, some insights can be gained: MDR-TB can and should be addressed therapeutically in resource-poor settings; starting of treatment early is crucial; aggressive treatment regimens and high-end dosing are recommended given the lower potency of second-line antituberculosis drugs; and strategies to improve treatment adherence, such as directly observed therapy, should be used. Opportunities to treat MDR-TB in developing countries are now possible through the Global Fund to Fight AIDS, TB, and Malaria, and the Green Light Committee for Access to Second-line Anti-tuberculosis Drugs. As treatment of MDR-TB becomes increasingly available in resource-poor areas, where it is needed most, further clinical and operational research is urgently needed to guide clinicians in the management of this disease.

Comparative roles of levofloxacin and ofloxacin in the treatment of multidrug-resistant tuberculosis: preliminary results of a retrospective study from Hong Kong

OBJECTIVE

To compare levofloxacin and ofloxacin in the treatment of multidrug-resistant tuberculosis (MDR-TB).

PATIENTS AND METHODS

A retrospective analysis of 106 patients with MDR-TB (February 1990 through December 2000) receiving directly observed therapy with fluoroquinolone and accompanying drugs, which mainly included aminoglycosides, cycloserine, ethionamide/prothionamide, and pyrazinamide, was performed. Clinical data from 99 suitable patients were subjected to univariate analysis, stratification, and multiple logistic regression to compare the roles of levofloxacin and ofloxacin in multidrug regimens.

RESULTS

Forty patients received 612.5 +/- 79.0 mg qd levofloxacin (mean +/- SD), and 59 patients received 628.8 +/- 101.8 mg qd ofloxacin together with similar active second-line drugs for similar durations. The times to sputum smear (both 1.8 months) and culture conversion (both 2.1 months) were equivalent. Adverse reactions occurred at similar rates (10.0% vs 11.9%). The combined treatment success rate was 83.8%, being higher among ofloxacin-susceptible than ofloxacin-resistant cases (90.5% vs 64.0%, p < 0.01). The success rates for the levofloxacin group were 90.0% (overall), 96.2% (ofloxacin-susceptible cases), and 78.6% (ofloxacin-resistant cases) in comparison with 79.7%, 87.5%, and 45.5%, respectively, for the ofloxacin group (Mantel-Haenszel common odds ratio estimate, 4.0; p < 0.05). Bacillary susceptibility to ofloxacin, good adherence, radiographic extent of one lung or less, and use of levofloxacin were independent predictors of favorable outcome (odds ratios, 7.6 to 21.3). One patient each from both groups relapsed.

CONCLUSION

Levofloxacin was found to be more efficacious than ofloxacin when incorporated into multidrug regimens used for treatment of MDR-TB.

Fluoroquinolone resistance in patients with newly diagnosed tuberculosis

Fluoroquinolones are widely used for the treatment of bacterial infections and are also second-line therapy for tuberculosis. However, fluoroquinolone resistance in patients with newly diagnosed cases of tuberculosis is not routinely assessed. We performed in vitro susceptibility testing of Mycobacterium tuberculosis to fluoroquinolones for all culture-confirmed tuberculosis cases in adults that were diagnosed at Johns Hopkins Hospital (Baltimore) between January 1998 and March 2002. Fifty-five patients were included in the study; 19 received fluoroquinolone monotherapy before the initiation of antituberculosis therapy. Two of 55 M. tuberculosis isolates (4%; 95% CI, 1%-13%) had decreased susceptibility to fluoroquinolones, including 2 of 19 of those from patients who had received fluoroquinolones (11%; 95% CI, 1%-33%) and 0 of 36 isolates from those who had not (95% CI, 0%-10%). The 2 fluoroquinolone-resistant M. tuberculosis strains were both from patients with acquired immunodeficiency syndrome and a CD4+ lymphocyte count of <50 cells/mm3. The incidence of M. tuberculosis fluoroquinolone resistance in this small sample of patients with newly diagnosed tuberculosis was high, particularly among patients with prior fluoroquinolone exposure.

Multidrug-resistant tuberculosis in a lung transplant recipient

Tuberculosis infection has been a relatively rare complication after lung transplantation. However, as more countries in which Mycobacterium tuberculosis infection remains endemic embark on lung transplant programs, the occurrence of multidrug-resistant tuberculosis after transplantation is a genuine threat. We report the first case of multidrug-resistant tuberculosis in a double-lung transplant recipient who probably acquired the disease from the donor. We discuss the problems in clinical management of post-transplant tuberculosis infection and of drug-resistance.

Ciprofloxacin-induced acute psychosis in a patient with multidrug-resistant tuberculosis

Tuberculosis (TB) increasingly appears in a multidrug-resistant form (MDR-TB) in Europe, too. Treatment remains difficult due to various side effects of the multi-drug-regimens. Ciprofloxacin is widely used as one of the few TB-second-line drugs. We report on the course of a ciprofloxacin-induced acute psychosis in a patient with MDR(isoniazid, streptomycin)-TB which resolved after cessation of ciprofloxacin treatment and introduction of a novel oxazolidone. Careful treatment considerations particularly in patients with additional predisposing factors to neuropsychiatric symptoms are recommended in the potentially dangerous MDR-TB, thus creating an enormous therapeutic challenge.

Recent developments in the treatment of tuberculosis

The history of chemotherapy of tuberculosis commenced in 1944 with the discovery of streptomycin. Currently, short-course chemotherapy comprising rifampicin, isoniazid, pyrazinamide and ethambutol/streptomycin administered under directly observed settings for 6 months (initially all four drugs followed by the former two drugs), constitutes the cornerstone treatment for pulmonary tuberculosis. Multi-drug resistant tuberculosis requires alternative chemotherapy, ideally in the form of individualised regimens, for management. To improve on the duration of chemotherapy for drug-susceptible tuberculosis and to achieve better treatment for multi-drug resistant tuberculosis as well as latent tuberculosis infection, there arises a genuine need for new drugs. The quest for new agents is, however, impeded by obstacles. Hopefully, tackling these through collaborative public-private partnerships on an international scale will lead to a fruitful outcome.

Drug resistant tuberculosis in diabetes mellitus: a retrospective study from south India

This study was conducted in a tertiary care teaching hospital in south India to evaluate the association of drug resistant tuberculosis (TB) in diabetic subjects. There were: 361 subjects with positive mycobacterial culture and susceptibility tests results over a 3-year period; 267 (74%) acid-fast bacillus smear positive; and 94 (26%) smear negative cases. One hundred and seventy-seven (49%) had resistant isolates to any one first line antiTB drugs (resistant group) and 184 (51%) had isolates sensitive to all drugs (non-resistant group). In the resistant and non-resistant subjects the mean duration of TB symptoms was, respectively, 22 months and 4.5 months, past history of TB 126 (71%) and 48 (26%), past antiTB drug therapy 126 (71%) and 47 (25%), inadequate anti TB drug therapy 42 (24%) and 23 (13%), HIV positive six and 13 subjects. There were 72 diabetic subjects [35 and 37, respectively] with a duration of diabetes 5.8 +/- 7.5 years and 3.7 +/- 5.0 years in the resistant and non-resistant groups. Twenty-six per cent of the diabetic subjects (19/72) had multi-drug resistantTB. Drug resistance to first line anti-TB drugs was not found to be associated with diagnosis or duration of diabetes mellitus.

Fluoroquinolones, tuberculosis, and resistance

Although the fluoroquinolones are presently used to treat tuberculosis primarily in cases involving resistance or intolerance to first-line antituberculosis therapy, these drugs are potential first-line agents and are under study for this indication. However, there is concern about the development of fluoroquinolone resistance in Mycobacterium tuberculosis, particularly when administered as monotherapy or as the only active agent in a failing multidrug regimen. Treatment failures as well as relapses have been documented under such conditions. With increasing numbers of fluoroquinolone prescriptions and the expanded use of these broad-spectrum agents for many infections, the selective pressure of fluoroquinolone use results in the ready emergence of fluoroquinolone resistance in a diversity of organisms, including M tuberculosis. Among M tuberculosis, resistance is emerging and may herald a significant future threat to the long-term clinical utility of fluoroquinolones. Discussion and education regarding appropriate use are necessary to preserve the effectiveness of this antibiotic class against the hazard of growing resistance.

Community-based therapy for multidrug-resistant tuberculosis in Lima, Peru

BACKGROUND

Despite the prevalence of multidrug-resistant tuberculosis in nearly all low-income countries surveyed, effective therapy has been deemed too expensive and considered not to be feasible outside referral centers. We evaluated the results of community-based therapy for multidrug-resistant tuberculosis in a poor section of Lima, Peru.

METHODS

We describe the first 75 patients to receive ambulatory treatment with individualized regimens for chronic multidrug-resistant tuberculosis in northern Lima. We conducted a retrospective review of the charts of all patients enrolled in the program between August 1, 1996, and February 1, 1999, and identified predictors of poor outcomes.

RESULTS

The infecting strains of Mycobacterium tuberculosis were resistant to a median of six drugs. Among the 66 patients who completed four or more months of therapy, 83 percent (55) were probably cured at the completion of treatment. Five of these 66 patients (8 percent) died while receiving therapy. Only one patient continued to have positive cultures after six months of treatment. All patients in whom treatment failed or who died had extensive bilateral pulmonary disease. In a multiple Cox proportional-hazards regression model, the predictors of the time to treatment failure or death were a low hematocrit (hazard ratio, 4.09; 95 percent confidence interval, 1.35 to 12.36) and a low body-mass index (hazard ratio, 3.23; 95 percent confidence interval, 0.90 to 11.53). Inclusion of pyrazinamide and ethambutol in the regimen (when susceptibility was confirmed) was associated with a favorable outcome (hazard ratio for treatment failure or death, 0.30; 95 percent confidence interval, 0.11 to 0.83).

CONCLUSIONS

Community-based outpatient treatment of multidrug-resistant tuberculosis can yield high cure rates even in resource-poor settings. Early initiation of appropriate therapy can preserve susceptibility to first-line drugs and improve treatment outcomes.

Tuberculosis in older people: a retrospective and comparative study from Hong Kong

OBJECTIVES

To compare tuberculosis (TB) in older and younger patients.

DESIGN

A retrospective and comparative observational study.

SETTING

Four chest clinics and two chest hospitals in Hong Kong.

PARTICIPANTS

All notifications from the participating hospitals and clinics in 1996 were extracted from the TB notification registry. The characteristics of patients aged 65 and older were compared with a one-in-three random sampling of those aged 16 to 64.

MEASUREMENTS

Demographic, clinical, radiological, and laboratory data of the two groups were compared alongside treatment and outcomes.

RESULTS

Older people with TB were more likely to be male, to smoke, to have had TB previously, to have coexisting medical diseases, to be socioeconomically disadvantaged, and to weigh less than younger people with TB. Dyspnea, weight loss, and malaise were more common, whereas extrathoracic lymph node enlargement was less common. Chest radiograph showed more extensive disease and lower zone involvement. Positive tuberculin test was present in only 61.9%. Sputum bacteriology was more likely to be positive. There was a longer delay in presentation and commencement of treatment, and 77.2% required at least one admission. Adverse effects of treatment, notably hepatic dysfunction, occurred more commonly. Fluoroquinolones appeared well tolerated. Only 72.5% of the older people were cured or completed their treatment. Mortality was 16%. Age of 65 and older, comorbidity, socioeconomic disadvantage, moderate-extensive disease, positive sputum smear, and poor adherence were factors independently associated with unfavorable outcomes (P <.001 to P = .01; odds ratios = 1.61-27.02).

CONCLUSION

Substantial differences were found between older and younger TB patients. Many of these were associated with unfavorable outcome. Increased awareness in disease recognition and better medical and social support are therefore needed in addressing the growing problem of TB in older people.

Limited tolerability of levofloxacin and pyrazinamide for multidrug-resistant tuberculosis prophylaxis in a solid organ transplant population

STUDY OBJECTIVE

To determine the long-term tolerability of prophylactic administration of pyrazinamide and levofloxacin in patients possibly exposed to multidrug-resistant tuberculosis (MDRTB) after undergoing solid organ transplantation.

DESIGN

Retrospective analysis.

SETTING

Community outpatient clinic.

PATIENTS

Forty-eight recipients of solid organ transplants beginning prophylaxis for MDRTB during August 1999 after possible exposure to a single index case of multidrug-resistant Mycobacterium tuberculosis within our community

INTERVENTION

Prophylaxis consisted of pyrazinamide 30 mg/kg/day plus levofloxacin 500 mg/day, administered for 1 year.

MEASUREMENTS AND MAIN RESULTS

Thirteen (27.1%) of the 48 patients completed therapy; 27 (56.3%) discontinued therapy within 4 months due to adverse drug events. Gastrointestinal intolerance was the major adverse event resulting in early discontinuation.

CONCLUSION

Prophylaxis of MDRTB with levofloxacin and pyrazinamide was associated with limited tolerability due to the high frequency of adverse events. While we search for a better tolerated prophylactic regimen, close monitoring for adverse reactions is recommended.

Fluoroquinolones and tuberculosis

Tuberculosis (TB) remains one of the main causes of morbidity worldwide, and the emergence of multi-drug resistant (MDR) Mycobacterium tuberculosis strains in some parts of the world has become a major concern. The decrease in activity of the major anti-TB drugs, such as isoniazid and rifampicin, is an important threat and alternative therapies are urgently required. The anti-TB activity of the fluoroquinolones has been under investigation since the 1980s. Many are active in vitro but only a few, including ofloxacin, ciprofloxacin, sparfloxacin, levofloxacin and lomefloxacin, have been clinically tested. Fluoroquinolones can be used in co-therapy with the available anti-TB drugs. However, the choice of fluoroquinolone should be based not only on the in vitro activity, but also on the long-term tolerance. Fluoroquinolones are novel anti-TB drugs to be used when a patient is infected with a MDR-TB strain.

Postantibiotic effects of antituberculosis agents alone and in combination

The postantibiotic effects (PAEs) of seven antimycobacterial agents, tested at their respective peak concentrations in serum alone and in different combinations, against Mycobacterium tuberculosis ATCC 27294 were studied with a radiometric culture system in parallel with the viable count method. Rifampin gave the longest PAE (67.8 h) among the drugs used alone, and combinations of first-line drugs generally gave PAEs longer than 120 h. The data obtained might help provide a better understanding of the scientific basis of intermittently administered antituberculosis chemotherapy.