~ LONG-TERM TREATMENT OF DAPSONE-RESISTANT LEPROSY WITH RIFAMPICIN: CLINICAL AND BACTERIOLOGICAL STUDIES

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1 I NTERNATI ONAL J OURNAL OF L EPROSY Vlume 44. Numbers I & 2 Prinled in Ilu' U.S.A. ~ LONG-TERM TREATMENT OF DAPSONE-RESISTANT LEPROSY WITH RIFAMPICIN: CLINICAL AND BACTERIOLOGICAL STUDIES R.J.W. Rees, M.F.R. Waters, J.M.H. Pearsn*, H.S. Helmy and A.B.G. Laing Natinal Institute fr Medical Research, Lndn, and Leprsy Research Unit, Sungei Bulh, Selangr, Malaysia Althugh dapsne (DDS) cntinues t b~ the standard treatment fr the majrity f leprsy patients, alternative drugs are required fbr the therapy f the ever increasing number f patients develping sulphne resistance. Because a high prprtin f patients with active leprmatus leprsy in Malaysia nw have DDS resistance (muse ft-pad prven), they have been used in many f ur lng-term chemtherapeutic trials in leprsy. Clfazimine was the first alternative drug used in ur DDS-resistant leprsy trials, but the intrductin f rifampicin prvided a particularly imprtant alternative drug because f its bactericidal effect with very rapid killing f M.leprae (1,2,3). Since 1968 we have treated well ver 100 leprmatus patients with rifampicin in varius studies, including shrt and lnger-term trials. Fifty f these rifampicin treated patients had prven DDS resistance and nw sme f these patients have been n cntinuus rifampicin therapy fr up t 7 years. Therefre these patients frm the basis f ur presentatin n the lng-term treatment f sulphne resistant leprsy with rifampicin. Hwever, because it ~as been shwn that DDS-resistant M.leprae (6 strains) were as sensitive t rifampicin as DDS-sensitive rganisms (4 strains) (R.J.W. Rees, persnal cmmunicatin), detailed bacterilgical studies were undertaken n 28 f the patients t determine the efficiency f rifampicin t "eradicate" persisting viable M.leprae. We applied the same techniques as we had used fr detecting persisting viable M.leprae in leprmatus patients treated fr 10 years with DDS (4). *Present address: Medical Research Cuncil Leprsy Prject, PO Bx 1005, Addis Ababa, Ethipia. 159

2 160 Internatinal Jurnal 0./ Leprsy 1976 CLINICAL STUDIES METHODS. All patients frm the start f treatment have been subjected t regular independent clinical, histlgical (bipsy index) ' and bacterilgical (BI and MI) assessment using ur standard methds (5). The incidence and severity f erythema ndsum leprsum (ENL) and the nature and incidence f txic side effects were als assessed. with ne exceptin rifampicin treatment was 600 mg daily (ne patient 600 mg rifampicin nce weekly). The majrity f patients received cmbined therapy (rifampicin + thiambutsine, 1.0 g nce weekly by injectin r 1.0 g twice daily by muth) in the hpe f reducing the emergence f drug resistance~ thse receiving rifampicin mntherapy were either already knwn t be thiambutsine/ thiacetazne resistance (muse ft-pad prven) r entered the study befre the plicy f cmbined therapy was adpted. RESULTS. By all assessments all patients shwed gd and steady imprvement irrespective f the particular rifampicin regimen. Initial clinical imprvement was particularly rapid being detected in 2-3 weeks (especially relief f nasal blckage) as cmpared with 2-3 mnths with DDS. The MI fell just as fast in the DDS resistant pa~ients as in previusly untreated leprmatus patients treated with rifampicin. The BI hwever fell at apprximately the,same rate as in patients treated with ther effective antileprsy drugs (Fig. 1). ENL was nt significantly mre cmmn, severe r rapid in nset than we have experienced in nn-resistant leprmatus patients treated with DDS,.hwever the results are nt strictly cmparable as the resistant patients usually have less severe leprsy than the nnresistant. Nne f the patients n daily rifampicin have s far develped signs f "immunlgical" txicity r prduced rifampicin dependent antibdies. Hwever, ne patient n 600 mg weekly cmplained f fever and abdminal symptns after three years f treatment, but withut rifampicin dependent antibdies and has nw been changed t 600 mg rifampicin daily. There was n decrease in the platelet cunts in the patient.

3 44, 1 & 2 Rees et al: Dapsne Resistant Leprsy Treat ed with Rifampicin CO Treatment (years) FIG.l. Fall in bacterilgical index (BI) in 28 DDS resistant leprmatus patients treated with rifampicin. Number f patients in brackets.

4 162 Internatinal Jurnal f Leprsy 1976 BACTERIOLOGICAL STUDIES METHODS. In this study the bacterilgical prgress f the patients was apsessed by attempting t islate viable M.leprae frm their tissues by muse ft-pad inculatin, by the methd used fr mnitring similarly patients n lngterm DDS (4). The tissue bipsies were hmgenised, their acid-fast bacillary (AFB) cntent determined, and the suspensin inculated int bth hind ft pads f 6 immunlgically suppressed female CBA mice (thymectmy fllwed by 5 expsures t 200R at 2-week intervals, T/R). Smetimes additinal nrmal mice were als inculated. The maximum. 5 number 4 0f AFB inculated per ft pad was 10 fr T/ R mice and 10 fr nrmal mice, hwever all tissue suspensins were inculated whether r nt the bacillary yields reached these maxima r a cuntable number f bacilli. Surviving mice were sacrificed 12 mnths fllwing inculatin and bth ft pads harvested individually and an increased yield >3 scred as a psitive islate. Where pssible bipsies f skin, nerve (usually superficial radial, ccasinally sural), striated muscle (triceps r quadriceps femris) and scrtal skin (t include smth darts muscle) were btained and each tissue hmgenised and prcessed separately. Twentyeight f the 50 DDS resistant patients receiving rifampicin regimens were submitted t these special studies and their bipsy tissues mnitred fr persisting viable M.leprae after 0.5, 1, 2 and 2.5 years treatment, 5 f these patients were mnitred a secnd time, 3-5 years after treatment. The details f these patients are given in Table 1. RESULTS. psitive islates frm ne r mre f the bipsied sites were btained frm 4 f 6 patients treated fr 0.5 years, 4 f 10 patients treated fr 1 year, 9 f 11 patients treated fr 2 years and n islates frm the ne patient treated fr 2.5 years (Table 2). Of the 5 patients mnitred a secnd time, 4 were first mnitred at 2 and ne at 2.5 years, 3 had psitive islates fr the first time at the later mnitring (Table 3) Thus verall, f the 28 patients mnitred nce r twice after 0.5 t 5 years treat-

5 44, 1 & 2 Rees et al: Dapsne Resistant Leprsy Treated with RI/ampicin 163 TABLE 1 DETAILS OF RIFAMPICIN TREATMENT AND.~ IMES OF MONITORING M.LEPRAE FROM 28 DAPSONE RESISTANT PATIENTS NUMBER OF PATIENTS TREATMENT THIA TOTAL RIF + THIA RIF ALONE (YEARS) RESISTANT 6 6 A MONITORED A SECOND TIME RIF = Rifampicin: 600 mg daily THIA = Thiambutsine: 1 9 twice daily per s r 1 9 nce weekly by injectin A One patient received 600 mg rifampicin nce weekly

6 164 Internatinal Jurnal 0/ Leprsy 1976 TABLE 2 PROPORTIONS OF ISOLATES OF M.LEPRAE OBTAINED FROM FOUR TISSUE SITES IN 28 DDS RESISTANT PATIENTS TREATED WITH RIFAMPICIN FOR YEARS TREATMENT PATIENTS: B I 0 P S Y SIT E S (YEARS) PROPORTION PROPORTION POSITIVE POSITIVE SKIN MUSCLE NERVE DARTOS A /6 2/6 1/5 1/6 2/ /10 2/9 1/9 1/10 3/ /11 4/11 4/1C 4/8 5/ /1 0/1 0/1 A One patient received 600 mg Rifampicin nce weekly.

7 44, 1 & 2 Rees et al: Dapsne Resistant Leprsy Treated with R?(ampicin 165 TABLE 3 COMPARISON OF ISOLATES OF M.LEPRAE OBTAINED ON TWO OCCASIONS FROM 5 DDS RESISTANT PATIENTS TREATED WITH RIFAMPICIN PATIENT N. TREATMENT (YEARS) B lop S Y SIT E S POSITIVE (+) OR NEGATIVE (0) ISOLATES SKIN MUSCLE NERVE DARTOS

8 166 Internatinal Jurnal f Leprsy 1976 ment with rifampicin, 20 had psitive islates and in particular all 11 patients treated fr 2-5 years had psitive islates at ne r mre f these sites bipsied. There was n significant dif,ference between mn- and cmbined-therapy in the persistence f viable M.leprae. Psitive islates frm 2 patients after 0.5 and ne patient after 1 year were tested fr rifampicin sensitivity by passage in mice and all prved t be sensitive, all 3 were n cmbined therapy. The pattern f results btained in this study t mnitr particular tissues frm patients after lnger-term rifampicin therapy are similar t thse btained frm patients n lng-term DDS therapy, based n identical methds. These similarities based nw n much mre extensive data mre firmly justify the pattern as being characteristic f persisting viable M.leprae frm leprmatus patients after several years f therapy. Thus, frm the fur chsen tissues using T/R mice limited multiplicatin f M.leprae was btained in mice in 13-25% f the ft pads inculated. Mrever, at anyne time patients harburing viable bacilli capable f multiplying in the muse mre usually were islated frm ne r smetimes tw rather than all 4 bipsied sites. There is suggestive evidence that scrtal skin is mre likely t harbur such rganisms and that frm this site they are mre likely t multiply in the muse. Analysis f this data is presented in Table 4. CONCLUSIONS AND DISCUSSION Rifampicin treatment is fully effective ver a perid up t 7 years in the treatment f patients with DDS resistance and this finding is cnsistent with the results in mice shwing that DDS resistant strains f M.leprae are as sensitive t rifampicin as are DDS sensitive strains. Standard clinical, bacterilgical and histlgical assessments shwed n evidence f relapse in any f the 50 patients treated with rifampicin and therefre n evidence in the perid f time cvered f the emergence f rifampicin resistant strains f M.leprae. Hwever, the number f patients invlved, the relatively shrt time cvered and the fact that the majrity f patients received cmbined therapy des nt exclude the

9 44, 1 & 2 Rees et at: Dapsne Resistant Leprsy Treated with Rifampicin 167 TABLE 4 DATA ON DISTRIBUTION OF M.LEPRAE ISOLATES FROM THE FOUR BIOPSY SITES IN PATIENTS WITH PERSISTING VIABLE BACILLI B lop S Y S I T E SKIN MUSCLE NERVE S DARTOS POSITIVE FOOTPAD ('Y ) POSITIVE SITES ('Y ) (9/ 19) (6/ 17) (9/ 20) 73 (11/ 15 ) P 0 S I T I V E SIT E S 1 SITE (12 PATIENTS) 2 SITES (6 PATIENTS) 3 SITES (1 PATIENT) 4 SITES (2 PATIENTS)

10 168 Internatinal Jurnal f Leprsy 1976 pssible emergence f rifampicin resistance. Since the majrity f ur DDS resistant patients received cmbined therapy, it is tempting but nt cnclusive that this regimen prevented the e.mergence f rifampicin resistance. We cnsider that althugh the patients in this study had "relapsed" active leprmatus leprsy with DDS resistant M.leprae it is justifiable t equate their respnse t rifampicin t that btained in previusly untreated leprmatus patients. Accepting this assumptin the results clearly shw that unfrtunately ur hpes f a quick "cure" by rifam~icin have been disappinting, since after 2-5 years f cntinuus therapy the rifampicin treated patients still harbur persisting viable rganisms. Using the same methds we had earlier established the existence f persisting viable M.leprae in previusly untreated patients given DDS cntinuusly fr 10 years. Since it has been established that such DDS treated patients when taken ff treatment can relapse we assume that ur criteria fr the detectin f persisting viable rganisms using the muse fully justifies the methd. On this basis therefre we have within a perid f 5 years f cntinuus rifampicin treatment failed t shw that this highly bactericidal drug will necessarily eradicate persister rganisms any mre efficiently than DDS. One must cnclude, nt with an answer but a questin: can patients with leprmatus leprsy ever he cured by chemtherapy alne? ACKNOWLEDGEMENTS All the data presented in this paper is part f crdinated chemtherapeutic trials undertaken by the Medical Research Cuncil at the Leprsy Research Unit in Malaysia and mre recently in Ethipia. The trials reprted here were crdinated frm the Natinal Institute fr Medical Research, Lndn, and the clinical cnduct and expertise undertaken by Drs J.M.H. Pearsn and M.F.R. Waters. The muse ftpad studies were undertaken in Lndn n refrigerated tissues despatched by air. The assessments f rifampicin-dependent antibdies were undertaken by Dr Sheila Wrlledge f the Department f Haematlgy, Ryal pstgraduate Medical

11 44, 1 & 2 Rees et at: Dapsne Resistant Leprsy Treat ed with Rifamp icin 169 Schl, Hammersmith. Messr s. Gr upp Lepetit f Milan generusly prvided free all the rifampicin. One f us (RJWR) is grateful t the British Leprsy Relief Assciatin (LEPRA) fr prviding funds t attend this Cnference. REFERENCES Rees, R.J.W., Pearsn, J.M.H. and Waters, M.F.R. (1970). Experimental and clinical studies.n rifampicin in the treatment f leprsy. Br.med.J. l, 89. Shepard, C.C., Levy, L. and Fasal, P. (1972). Rapid bactericidal effect f rifampicin n Mycbacterium leprae. Am.J.trp.Med.Hyg. 11, 446. Levy, L., Shepard, C.C. and Fasal, P. (1973). Death f Myc.leprae fllwing treatment f leprsy patients with 1500 mg rifampicin in a single dse. Int.J.Lepr. 41, 490. Waters, M.F.R., Rees, R.J.W., McDugall,A.C. and Weddell, A.G.M. (1974). Ten years f dapsne in leprmatus leprsy: Clinical, bacterilgical and histlgical assessment and the findings f viable leprsy bacilli. Lepr.Rev. 45, 288. Waters, M.F.R., Rees, R.J.W. and Sutherland, I. (1967). Chemtherapeutic trials in leprsy. 5. A study f methds used in clinical trials in leprmatus leprsy. Int.J.Lepr. 12, 311.