A second case of multidrug-resistant Mycobacterium leprae isolated from a Japanese patient with relapsed lepromatous leprosy

Emergence of drug resistant strains of Mycobacterium leprae was reported soon after the introduction of dapsone (diamino-diphenyl sulphone, DDS) for leprosy treatment (6, 10, 11). Three cases of multidrug-resistant strains of M. leprae have been reported recently (2, 8, 9, 13). In order to prevent multiple drug resistant strains of M. leprae from developing, current leprosy control strategies are based on early detection of cases and treatment with multidrug therapy (MDT) as recommended by the World Health Organization (WHO). We report here the identification of a multidrug-resistant strain of M. leprae from a patient who received inadequate therapy for leprosy. The drug resistant profile of the isolated strain was confirmed by the mouse footpad method and the identification of mutations in genes previously shown to be associated with resistance to each drug was made.     

Dapsone syndrome in Vanuatu: a high incidence during multidrug treatment (MDT) of leprosy.

Side-effects of leprosy treatment with dapsone are said to be uncommon, with drug allergy occurring in only one of every several hundred patients treated with dapsone. The dapsone or sulphone syndrome (DDS) has been recognized since the earliest days of sulphone therapy but until recently its incidence had been decreasing. In Vanuatu, during the years 1988-1991, nine leprosy patients have developed the dapsone syndrome, four of whom have died. During the last 4 years only 37 patients were started on treatment, which is an incidence of the dapsone syndrome of 24% with a fatality rate of 11%. All the patients were being given multi-drug treatment (MDT) of daily dapsone (100 mg) and clofazimine (50 mg) and monthly rifampicin (600 mg) and clofazimine (300 mg). There has been speculation that the increased incidence of what was previously described as a rare reaction is due to the use of MDT, and the reasons for this are discussed. We feel the increase in the number of reactions in Vanuatu since starting MDT is probably due to the high starting dose of 100 mg of dapsone, possibly enhanced by the combination with clofazimine and rifampicin and a genetic susceptibility of the Melanesian population.     

Results from cation and mass fingerprint analysis of single cells and from ATP measurements of M. leprae for drug sensitivity testing: a comparison

The physiologic states of Mycobacterium leprae isolated from patient biopsies were studied using single cell mass spectrometry by laser microprobe mass analysis (LAM-MA) and ATP bioluminescence assay. The changes in the physiologic state of M. leprae after the patients had been treated with dapsone (DDS) monotherapy were also studied. The shift of the low intracellular Na+, K+-ratio of untreated M. leprae cells to higher values under DDS therapy, as measured from a limited number of single bacteria, correlates with a decrease in the ATP content. Further information on the influence of the drug could be drawn from the multivariate analysis of mass fingerprints of the organic matrix of the cells. Evidence is provided that the combination of the measurement of the intracellular cation ratios and of the mass fingerprint analysis could give fast answers to the question of drug resistance and to the persister hypothesis. The ATP bioluminescence assay and the single cell mass analysis should be alternatives to the mouse foot pad test.     

Superiority of the neonatally thymectomized Lewis rat (NTLR) to monitor a clinical trial in lepromatous leprosy of the two regimens of rifampin and dapsone

The ability of the neonatally thymectomized Lewis rat (NTLR) and the congenitally athymic (nude) rat systems to detect low numbers of viable Mycobacterium leprae in tissues from lepromatous leprosy patients undergoing short-course chemotherapy was compared with that of the commonly employed mouse foot pad assay. Fifteen previously untreated lepromatous patients were randomly assigned to treatment regimens of either a single initial 1500 mg dose of rifampin plus daily doses of 100 mg of dapsone, or weekly doses of 900 mg of rifampin plus daily doses of 100 mg of dapsone. Four skin biopsies from each patient taken sequentially up to one month after initiation of therapy were used as the source of the M. leprae inocula. Only 2 of 57 skin biopsies (2%) proved positive for viable M. leprae following direct inoculation into mouse foot pads. However, 30 of 58 patient biopsies (52%) provided positive for viable M. leprae following direct passage into NTLR foot pads or in subsequent mouse subpassage. In contrast, the nude rat was observed to be a poor monitor of such trials. Although not statistically significant, the regimen consisting of a single dose of rifampin plus daily dapsone resulted in a lower percentage of biopsies found to contain viable M. leprae at each of the four sampling intervals.     

Viability and drug susceptibility testing of M. leprae using mouse footpad in 37 relapse cases of leprosy

Mycobacteria leprae isolates obtained from 37 referral relapse cases of leprosy (37 skin and 10 nerve biopsy samples) received during the years 1994-2001, were tested for viability and drug sensitivity in the mouse footpad. A significant M. leprae yield in the footpads of control mice was obtained, with 32/47 (68%) isolates (from 26 cases) thus confirming viability. Of the 28 isolates successfully drug tested, 6 (21%) were resistant to one or more drugs. All except one, were multidrug treated cases (5/24 = 21%). One of the isolates was resistant to all three drugs, i.e., dapsone (di-aminodiphenyl sulphone, DDS), rifampin (RFP), and clofazimine (CLF). Two were resistant to two drugs, i.e., DDS and RFP, and each of the others were mono resistant to DDS, RFP, or CLF. Notably, one of the isolates that showed combined resistance to DDS and RFP was derived from a borderline tuberculoid case. Also, in one case skin and nerve showed that discordance viz: M. leprae derived from skin were resistant to RFP, while those derived from nerve tested sensitive to all three drugs, indicating tissue related difference.     

Susceptibility of strains of Mycobacterium leprae isolated prior to 1977 from patients with previously untreated lepromatous leprosy

Because of the recent spate of reports of primary resistance to dapsone among patients with lepromatous leprosy, largely to small concentrations of the drug, a survey was made of the results of dapsone-susceptibility testing of strains of Mycobacterium leprae isolated before 1977 among six laboratories which employed the mouse foot pad technique for this work prior to that time. Data have been found for strains that had been isolated from 73 patients, representing 19 countries and dependencies, with previously untreated lepromatous leprosy; all 73 strains were inhibited from multiplication by dapsone administered to mice in a concentration of 0.0001 g per 100 g mouse diet. These data suggest that the properties of M. leprae isolated from previously untreated patients with respect to susceptibility to dapsone have changed since the years preceding 1977.     

Intermittent chemotherapy of experimental leprosy in mice

In this study we assess the degree of prolonged bacteriostasis of Mycobacterium leprae after temporary exposure to ehtionamide or thiacetazone, and relate this to their efficacy when administered intermittently to mice with experimental leprosy infections. The results show that temporary exposure of M. leprae to either of these drugs results in a prolonged bacteriostatic effect, but that efficacy is rapidly lost as the interval between doses is increased. Using the mouse foot pad system, growth of M. leprae is not inhibited by thiacetazone when the frequency of administration is less than three times weekly. When ethionamide is administered once weekly, growth of M. leprae is inhibited but bactericidal activity is lost. When ethionamide is administered in combination with continuous dapsone therapy, either continuously or three times weekly, the bactericidal activity of the drug combination is greater than when either drug is administered alone. However, when ethionamide is administered once weekly in combination with continuous dapsone treatment, the bactericidal effect is identical to that when dapsone is given alone: that is, ethionamide makes no contribution to the combination.     

Activity of ofloxacin against Mycobacterium leprae in the mouse

Mice inoculated with 4800 Mycobacterium leprae in the left hind foot pad were treated from day 62 to day 150 after infection with 50 mg or 150 mg of ofloxacin per kg body weight, 150 mg pefloxacin per kg, or 50 mg prothionamide per kg. These drugs were administered by esophageal cannula 5 days weekly with dapsone (0.01 g per 100 g diet). Multiplication of M. leprae in the treated and in untreated control mice was assessed by monthly harvests. The treatment of mice with the smaller dosage ofloxacin, with pefloxacin, prothionamide, or dapsone uniformly resulted in a delay of multiplication of 4 months, compared to the multiplication of M. leprae in the untreated controls. The delay of multiplication (4 months) being 1 month longer than the duration of drug administration (3 months), all of the treatments may be considered as bacteriopausal or moderately bactericidal. In contast with these results, treatment of mice with 150 mg ofloxacin per kg resulted in no growth of the organisms whatever as late as 18 months after inoculation, strongly suggesting that, in that dosage, ofloxacin had killed all of the M. leprae. Such a profound killing activity has been observed only with rifampin. Although the pharmacokinetic characteristics of ofloxacin are different in man from those in the mouse, the daily dosage of 150 mg ofloxacin per kg body weight in the mouse is equivalent to 400 mg per day in man which is the usual therapeutic dosage; thus, the results obtained in the mouse may be extrapolated to man. Therefore, ofloxacin appears a very promising drug for the chemotherapy of leprosy.     

Activities of pefloxacin and ciprofloxacin against Mycobacterium leprae in the mouse

Because ciprofloxacin and pefloxacin are fluoroquinolones active against many mycobacterial species, both drugs were tested against Mycobacterium leprae in the mouse foot-pad system. Preliminary pharmacokinetic studies in the mouse showed that after a single oral dose of 150 mg/kg ciprofloxacin the peak serum concentration was 3.6 micrograms/ml, and after 50 mg/kg or 150 mg/kg pefloxacin peak serum concentrations were, respectively, 9.2 micrograms/ml and 16.9 micrograms/ml, the half-lives for serum elimination being about 2 hr for both drugs. The activity of daily 50 mg/kg and 150 mg/kg ciprofloxacin and pefloxacin against M. leprae was then tested in mice infected with 5 X 10(3) M. leprae. The growth of M. leprae was not prevented in mice treated continuously with either 50 mg/kg or 150 mg/kg ciprofloxacin, indicating that this drug had no or a limited bacteriostatic effect at the dosages used. In mice treated continuously with 50 mg/kg pefloxacin, growth of M. leprae was not prevented, but at monthly harvests the number of bacilli in the foot pads remained less than those of control mice (p less than 0.05). No growth of M. leprae occurred in mice treated continuously with 150 mg/kg pefloxacin. In mice treated for only 3 months with daily 150 mg/kg pefloxacin, the growth-delay that followed the stopping of the drug was 126 days, suggesting that approximately 99% of the M. leprae were killed. The pharmacokinetics of pefloxacin being more favorable in man than in the mouse, pefloxacin appears a possible drug for the chemotherapy of leprosy.     

Mutations in genes related to drug resistance in Mycobacterium leprae isolates from leprosy patients in Korea

OBJECTIVE: Identification of the presence and drug resistance of Mycobacterium leprae is key to the diagnosis and treatment of leprosy in non-endemic country like Korea. The aim of this study was to screen the drug target DNA such as folP, rpoB, gyr, and 23S rRNA of drug resistance strain of M. leprae. PATIENTS AND METHODS: Sequences of those genes were analyzed for the 104 bacterial index positive cases out of 171 leprosy patients in Korea using touchdown PCR, single stranded conformational polymorphism. RESULTS: Twenty (19.2%) cases have shown the mutations in folP gene of dapsone-resistant M. leprae in which three (2.89%) cases were mutations in two genes, folP and rpoB, of multidrugs resistant strains to dapsone and rifampin, and two (1.92%) cases in folP and gyr genes of resistance to dapsone and oflaxacin, respectively. Besides double mutation for folP gene was one case (0.96%) and for rpoB gene one case, respectively. There was no mutant isolates in 23S rRNA gene against clarithromycin. CONCLUSIONS: This result should leads to a better understanding of the status of multidrug resistant leprosy in Korea and may assist in the rapid diagnosis of drug resistant M. leprae and the choice of the appropriate treatment regimens.     

Class specific anti-Mycobacterium leprae antibody assay in lepromatous leprosy (BL-LL) patients during the first two to four years of DDS treatment

Previously, a slight decrease in antibodies against M. leprae antigen 7 was demonstrated after one year of dapsone (DDS) treatment in 14 of 15 patients with lepromatous (BL-LL) leprosy. The same patients have now received DDS from 11/2 to 4 years (median 3 years) and sera taken at the start, during, and at the end of the observation period have been retested for antibodies against M. leprae antigen 7 by radioimmunoassay and tested for IgA-, IgM-, and IgG-anti-M. leprae antibody activity by solid phase radioimmunoassay. Both IgA- and IgG-anti-M. leprae antibody activity and the activity of antibodies against M. leprae antigen 7 showed a decrease in activity after three years of DDS treatment to a median value of about one third of the activity in the sera taken at the start of the study. A smaller but significant decrease in IgM-anti-M. leprae antibody activity could be demonstrated. A transient increase in antibody activity (both measured by RIA and sRIA) could be demonstrated and related to reactions (reversal reaction and ENL) in five patients. No significant correlation could be found when IgA-, IgM-, and IgG-anti-M. leprae antibody activity was compared with antibodies against M. Leprae antigen 7 in individual sera.     

Studies on sulphone resistant strains of M. leprae in field and institutionalized cases of leprosy

The proportions of dapsone resistant strains of M. leprae in cases from the field and in patient institutionalized for treatment were compared. Identification of dapsone resistance was done by mouse-foot-pad experiments carried out in the Laboratory in Central Leprosy Teaching and Research Institute, Chengalpattu. A higher percentage of resistance was detected among institutional patients as compared to field cases. The distribution of M.I. ranges of M. leprae in dapsone resistant subjects was not different from that in dapsone sensitive cases.     

鼻分泌物中麻风分枝杆菌的聚合酶链反应检测及应用

目的 了解鼻分泌物中麻风分枝杆菌对麻风病传播的影响.方法 对流行区患者与密切接触者在治疗前、后采用扩增重复序列片段套式PCR法,并对患者皮肤损伤组织与鼻分泌物麻风分枝杆菌可变串联重复序列(VNTR)基因型进行比对.采用X2检验.结果 常规PCR检测38例麻风病患者阳性率为47.4%,31例接触者和29例流行村一般人群阳性率为8.3%,套式PCR检测阳性率分别为71.0%和40.0%.其中15份PCR阳性标本经DNA测序,确认鼻分泌物中有麻风分枝杆菌,而非流行区健康人鼻分泌物中无麻风分枝杆菌.未经治疗的多菌型与少菌型患者鼻分泌物中麻风分枝杆菌阳性率比较,差异有统汁学意义(P=0.039);分组及队列比较显示,治疗前和治疗6个月时,多菌型患者分泌物中麻风分枝杆菌阳性率无明显下降,但街切接触者治疗前后阳性率差异有统计学意义.患者皮肤损伤部位和鼻分泌物中的麻风分枝杆菌基因型一致.结论 多菌型患者鼻分泌物排菌是导致高流行区接触者、一般人群易感原因.短期治疗不能阻断鼻排菌.提示早期发现和治疗对阻断麻风病的传播尤为重要.     

Effect of simultaneous administration of interferon-gamma and chemotherapy against Mycobacterium leprae in experimental infection in nude mice

The possibility of synergy between immunotherapy with recombinant interferon-gamma (IFN-gamma) and chemotherapy with rifampin (RMP) and dapsone (DDS) against Mycobacterium leprae was examined in nude mice. IFN-gamma alone failed to show any effect on the growth of M. leprae in the nude mouse foot pad. No synergy was demonstrable between DDS, either at 0.0001% or at 0.001%, and IFN-gamma. A subinhibitory level of RMP with IFN-gamma was also ineffective, but RMP at 0.006% with IFN-gamma produced a statistically significant enhancement of killing (26-fold) when compared with RMP at 0.006% only. It should be emphasized, however, that results obtained in the immunodeficient nude mouse model may not be comparable to those which might have been given by lepromatous leprosy patients.     

Primary dapsone-resistant leprosy in San Francisco

The dapsone sensitivity of strains of Mycobacterium leprae from 54 multibacilliferous untreated leprosy patients presenting to the United States Public Health Service Hospital in San Francisco, California, U.S.A., from 1978 to 1981 was studied by mouse foot pad inoculation. M. leprae from 53 patients were found fully sensitive to dapsone. M. leprae from one patient were resistant to only the lowest dietary level of dapsone, 0.0001%, since growth of the bacilli was inhibited by higher and clinically easily achievable levels. Mouse plasma dapsone levels confirmed the reliability of the drug-containing diets.     

Long-term efficacy of 2 year WHO multiple drug therapy (MDT) in multibacillary (MB) leprosy patients

Relapse rate estimates after 2 year WHO multiple drug therapy (MDT) in multi-bacillary (MB) leprosy vary. Between 1987 and 1994, 500 MB leprosy patients completing 2 year MDT were enrolled in a prospective relapse study. The majority of patients (N = 316) were treated and followed at the physician-staffed Cebu Skin Clinic (CSC), whereas others (N = 184) received therapy from government clinics and were followed by CSC technicians in the field. Relapse definition was an increased bacteriologic index (BI) and new skin lesions, supplemented with mouse footpad inoculations. Through 2002, follow-up was 5368 person-years, with a mean of 10.8 years per patient. The absolute relapse rate was 3% (15/498; 0.28/100 person-years), with a cumulative risk estimate of 3.9% at 15 yrs. For a subset of 217 patients followed for >or=12 yrs or until relapse, relapses occurred in 9% (13/142) attending the CSC, versus 3% (2/75) assessed in the field (p = 0.09). The rate for patients followed at CSC for >or=12 yrs and a pre-treatment BI >or=2.7+ was 13% (13/98). All relapses were BL or LL, with pre-treatment BI's of >or=2.7+. Relapses occurred long after completion of therapy, between 3 and 11 yrs from the midpoint of the examination without relapse to detection, or between 6 to 13 yrs to the actual year of detection, 7 occurring at >or=10 yrs. Lesion material from all relapses contained M. leprae that was rifampin and clofazimine sensitive, whereas 3 showed partial or full dapsone resistance. [Follow-up rigor and time], medical expertise, and pre-treatment bacterial load influence relapse rates after 2 yr MDT.     

Ofloxacin for the treatment of leprosy

Among the major commercially available fluoroquinolones, ciprofloxacin was inactive against M. leprae in mice; pefloxacin was active, 50 mg/kg daily showed bacteriostatic activity but 150 mg/kg daily displayed bactericidal activity; ofloxacin was more active than pefloxacin, 50 mg/kg daily exerted the same level of bactericidal effect as pefloxacin 150 mg/kg daily, and ofloxacin 150 mg/kg displayed profound killing activity. Two clinical trials with 6 months of pefloxacin and/or ofloxacin in 31 previously untreated lepromatous patients have been completed. Pefloxacin 400 mg twice daily or 800 mg once daily or ofloxacin 400 mg once daily were equally effective; definite clinical improvement with drastically decrease of morphological index to the baseline were observed in all patients at 2 months after beginning of treatment; about 99.99%, or 4 "logs", of organisms viable on Day 0 were killed by 22 doses of either pefloxacin or ofloxacin. The side effects from the two trials were rare and mild, and the patients tolerated extremely well the combinations of pefloxacin/ofloxacin plus multidrug therapy (MDT) regimen for multibacillary leprosy recommended by WHO. The amount of rifampicin-resistant mutants in lepromatous patients before treatment are no more than 4 "logs", thus, all rifampicin-resistant mutants may be eliminated by 22 doses of either pefloxacin or ofloxacin. It is, therefore, possible that the combination of ofloxacin and rifampicin may considerably shorten the required duration of MDT.     

Multiple mutations in the rpoB gene of Mycobacterium leprae strains from leprosy patients in Thailand

A new finding is reported of multiple mutations in the rpoB gene of 9 Mycobacterium leprae strains from leprosy patients in Thailand, who did not respond to therapy even when rifampicin, the main drug in multi-drug therapy was used. By means of sequence analysis of 9 Thai M. leprae strains, various mutations in 289 bps of the rpoB gene revealed forms of mutation never before described, such as multiple mutations (ie, mutation at two, three, six, seven, eight and nine positions in the rpoB gene), most of which were point-mutation substitutions (a few of which were silent), and some insertions. This investigation demonstrates that mutation in the rpoB gene of M. leprae strains from Thailand involves more variety than previously reported for rpoB mutation patterns in rifampicin resistance M. leprae strains.     

Nasal mucosa and skin of smear-positive leprosy patients after 24 months of fixed duration MDT: histopathological and microbiological study

The skin and nasal mucosa of 10 lepromatous leprosy patients who had completed 24 doses of fixed duration multidrug therapy (MDT) but who continued to be skin-smear positive for acid-fast bacilli (AFB) were examined histopathologically. The nasal mucosa showed granuloma fractions that exceeded those seen in the skin specimens, signifying that activity in this region subsides much more gradually than the activity in the skin. Mouse foot pad studies done using T900r mice with an inoculum from the nasal mucosa biopsy specimens of these patients did not demonstrate any growth of Mycobacterium leprae, indicating that these bacilli were not viable. A skin specimen from one patient grew significant amounts of bacteria in the T900r mouse foot pad. These results show that 2 years of treatment with MDT would prevent dissemination of M. leprae from the nasal mucosa and, therefore, should preclude further transmission of the disease. It also indicates that viable bacteria might persist in the skin of patients, especially those with an initial bacterial index of > or = 4+ who have completed 24 doses of regular MDT. Therefore, a more cautious approach to administering only 12 doses of MDT to highly positive multibacillary patients is suggested.     

Possible mode of emergence for drug-resistant leprosy is revealed by an analysis of samples from Mexico

Mexico is a country with sporadic leprosy cases, and the reemergence of drug resistance is a concern. In this study, molecular analysis of Mycobacterium leprae was employed to clarify the spread of drug-resistant leprosy. Thus, drug resistance-determining regions in the folP1, rpoB, and gyrA genes, which are associated with resistance to dapsone, rifampicin, and ofloxacin, respectively, were analyzed by direct sequencing of the PCR product. No mutations in the folP1 gene were observed in any of the 72 slit skin samples obtained from 38 patients, although two samples carrying a mutation at codon 425 in the rpoB gene, which confers resistance to rifampicin, a key component of multidrug therapy, were identified. In addition, a mutation at codon 91 in the gyrA gene, which correlates with ofloxacin resistance, was found in one sample. These results demonstrate the existence of rifampicin- and ofloxacin-resistant leprosy. Interestingly, wild-type and mutant sequences in the gyrA gene were found to coexist in one clinical sample. In addition, all three drug resistance-related mutations were found in only one of the two earlobes of the patients concerned, suggesting a possible pathway for the spread of drug-resistant M. leprae.