The Cases
Buruli ulcer (BU) was treated primarily with wide surgical excision until recent studies
confirmed the efficacy of oral rifampicin combined with intramuscular streptomycin.
Whether all-oral antibiotic regimens will be equally effective is unknown. This report
describes four patients with Mycobacterium ulcerans infection, all of whom received
rifampicin-based oral antibiotic therapy followed by surgical resection (three patients)
or oral antibiotics alone (one patient). Following oral antibiotics for between 4
and 8 weeks, viable M. ulcerans was not detectable by culture in three of the patients,
or by histology in a fourth patient from whom no specimen for culture was obtained.
All cases spent time in a BU-endemic area in coastal Victoria, Australia. Baseline
characteristics, diagnosis, treatment received, and histopathology of resected specimens
are detailed in Table 1. Clinical photographs are shown in Figures 1–
4. All patients gave informed consent for publication.
10.1371/journal.pntd.0000770.g001
Figure 1
Thirty-eight-year-old male with culture confirmed Buruli ulcer before, during, and
after treatment.
10.1371/journal.pntd.0000770.g002
Figure 2
Thirty-two-year-old male with culture confirmed Buruli ulcer before, during, and after
treatment.
10.1371/journal.pntd.0000770.g003
Figure 3
Twelve-year-old male with culture confirmed Buruli ulcer before, during, and after
treatment.
10.1371/journal.pntd.0000770.g004
Figure 4
Three-year-old female with culture confirmed Buruli ulcer before, during, and after
treatment.
10.1371/journal.pntd.0000770.t001
Table 1
Baseline Characteristics, Diagnosis, Treatment Received, and Histopathology and Microbiology
of Resected Specimens.
Case 1
Case 2
Case 3
Case 4
Age
38-year-old male
32-year-old male
12-year-old male
3-year-old female
Location of lesion
Right lateral malleolus
Right elbow
Lower back
Left thigh/buttock
Clinical form, size, and WHO category of lesion
[17]
Ulcer, 2cm diameter, category 1
Ulcer, 2cm diameter, srcategory 1
Pre-ulcerative form, 4cm diameter of induration, category 1
Ulcer, 2cm diameter, category 1
Region exposed
Bellarine Peninsula
Bellarine Peninsula
Bellarine Peninsula
Bellarine Peninsula
Specimen collected for diagnosis
Dry swab
Dry swab
Saline-moistened swab
Dry swab
Basis of diagnosis
PCR and culture
PCR and culture
PCR and culture
PCR and culture
Date of laboratory diagnosis
November 2006
October 2008
November 2008
November 2009
Principal drug
Rifampicin
600 mg daily
Rifampicin
600 mg daily
Rifampicin
450 mg daily
reduced to 600 mg 3× week after day 7
Rifampicin
10mg/kg daily
Secondary drug
Moxifloxacin
400 mg daily
Moxifloxacin
400 mg daily
Clarithromycin
250 mg twice daily
reduced to 250 mg twice daily, alternate days after day 7
Clarithromycin
15mg/kg daily in divided doses
Duration of oral drug therapy prior to excision
6 weeks
6 weeks
4 weeks
8 weeks (lesion not excised)
Outcome (follow-up period)
No recurrence (36 months)
No recurrence (13 months)
No recurrence (12 months)
Improved to match head sized palpable nodule
Histology/microbiology summary of excised specimen (cases 1–3; no excision case 4)
No AFB, culture negative, chronic granulomatous inflammation without necrosis
No AFB, chronic necrotizing granulomatous inflammation, culture not performed
AFB seen, culture negative, necrosis to edges of excision
Spontaneous discharge 4 weeks after ceasing antibiotics, AFB seen, PCR positive, culture
negative
Comment
Doses and duration reduced due to drug intolerance
Apparent relapse due to a culture negative “paradoxical” reaction [22]
In all patients, the diagnosis of M. ulcerans was confirmed by positive polymerase
chain reaction (PCR) and isolation of M. ulcerans by culture from swabs obtained prior
to treatment. Three patients had ulcerative lesions (Table 1: cases 1, 2, and 4; Figures
1, 2, and 4) and one had a pre-ulcerative lesion (Table 1: case 3 and Figure 3) from
which a saline-moistened swab of the lesion yielded a positive PCR and culture. For
the two adults (Table 1: cases 1 and 2), rifampicin was combined with moxifloxacin
for 6 weeks prior to resection. The two children (Table 1: cases 3 and 4) received
rifampicin combined with clarithromycin for either 4 weeks prior to resection (Table
1: case 3) or 8 weeks without resection (Table 1: case 4). In cases 1 and 3, resection
specimens were culture-negative, and culture was not performed in case 2, although
histology showed resolving inflammation and no acid-fast bacilli (AFB) by Ziehl-Neelsen
staining. In case 3, a Ziehl-Neelsen stained section showed persistent AFB but culture
was negative. He had received a reduced dose of rifampicin due to gastrointestinal
and neurological side effects and underwent earlier excision than planned at 4 weeks.
Inflammation of surrounding skin and the size of the lesion reduced during antibiotic
therapy in all four patients (Figures 1–4). PCR was not performed on surgical excision
specimens (cases 1–3). Excision and primary closure, rather than grafting, was achieved
in case 2 and 3, which had not been considered possible initially. Antibiotic treatment
was continued after surgery in all patients. Total treatment duration was 7 weeks
for case 3 and 12 weeks for cases 1 and 2. Case 4 was a 3-year-old girl who was treated
with oral combination antibiotics without surgery. After 8 weeks of rifampicin and
clarithromycin syrup, the ulcer had reduced to a very small palpable nodule. However,
4 weeks after ceasing antibiotic therapy the lesion became inflamed and discharged
pus. Acid-fast bacilli were seen and PCR for M. ulcerans was positive. However, subsequent
culture was negative at 3-months, suggesting an immune-mediated “paradoxical reaction”
driven by residual but dead mycobacterial cells, rather than a true failure of oral
antibiotic therapy. Following spontaneous discharge only a small blind ending sinus
remained.
Discussion
BU is a slowly progressive and destructive soft tissue infection, with the potential
for severe scarring and disability [1], [2]. The main burden of disease occurs in
sub-Saharan Africa [1], although in Australia, there are also active foci in coastal
Victoria, the Daintree region in the far north, and near Rockhampton, Queensland [3]–[6].
Until recently, the practice of wide surgical excision followed by grafting has been
the mainstay of treatment [2]. High relapse rates [7], prohibitive cost, and limited
access to surgery in endemic areas in Africa led to a renewal of interest in antibiotic
therapy, which had not appeared effective when first studied in field trials [8]–[10].
Based on promising experiments in the mouse footpad model [11]–[15], a small pilot
study established that the combination of oral rifampicin and intramuscular (IM) streptomycin
for 8 weeks was able to sterilize early BU lesions in humans. In this small study
of 21 pre-ulcerative patients in Ghana, even 4 weeks of rifampicin and streptomycin
led to culture negativity when lesions were surgically excised after antibiotic treatment
of varying durations [16]. Based on this result, WHO introduced and promoted a new
protocol of initial therapy with 8 weeks of daily oral rifampicin and IM streptomycin
for all patients with BU, although it was expected that many would still require surgery
[17]. Subsequently, Chauty et al. reported a case series of 224 patients with pre-ulcerative
and ulcerative BU who were treated with this regimen [18]. Of the 215 patients whose
lesions healed, 47% were treated only with antibiotics and did not require surgery.
Although there were no microbiological studies, recurrence of M. ulcerans infection
occurred in only two patients treated with antibiotics alone. In a recent randomized
trial of 151 patients, the majority of whom also did not have surgery, Nienhuis et
al. demonstrated that oral rifampicin plus IM streptomycin for 4 weeks then oral rifampicin
plus oral clarithromycin for 4 weeks was as effective as 8 weeks of oral rifampicin
plus IM streptomycin [19], indicating that a shorter duration of IM streptomycin is
also effective.
In Australia, surgery is widely accessible and remains the main treatment modality
for BU, although often in combination with oral antibiotics. As a result, the efficacy
of surgery alone compared with oral antibiotics alone is difficult to establish, although
relapses may be less when both modalities are used [6], [20], [21]. Australian consensus
guidelines [6], now 4 years old, recommend surgery alone for small lesions or surgery
combined with antibiotic therapy for more extensive disease. These guidelines include
the use of IV amikacin for severe disease, but in practice amikacin is rarely used
due to concerns about ototoxicity. Other oral antibiotics that appear to be active
against M. ulcerans in mice include moxifloxacin and clarithromycin [11]. Clarithromycin
is preferred in children due to its established safety record. There are unpublished
accounts of successful treatment of BU with oral rifampicin alone (W. Meyers, personal
communication), and the first published report of successful use of oral antibiotics
was of a North Queensland farmer with acute, oedematous M. ulcerans disease who received
oral rifampicin, clarithromycin, and ethambutol for 12 weeks immediately following
extensive but incomplete surgical excision [20]. The surgical resection margin showed
AFB, but further biopsies taken after 3 weeks of antibiotics due to concern about
relapse were smear and culture negative. In retrospect, this apparent clinical deterioration
may have been a “paradoxical reaction” [22] and the case demonstrated the principle
that oral antibiotics are able to prevent relapse after incomplete surgical excision,
even in a severe form of BU.
In the four patients we have described here, combination oral antibiotic therapy prior
to excision led to the inability to recover M. ulcerans by culture in the three cases
from whom a second specimen was submitted for culture, confirming that oral combinations
of antibiotics are capable of sterilizing lesions in humans, as Etuafal et al. demonstrated
for rifampicin plus IM streptomcyin. Two of the three patients we described received
oral antibiotics for a total of 12 weeks. However, negative culture results at excision
(4 weeks for case 3, 6 weeks for case 1) suggest that shorter periods may be effective
as suggested for the combination of rifampicin and streptomycin [16], [17]. Dossou
et al. also reported clinical improvement after 8 weeks of oral rifampicin and clarithromycin
[23] in a pregnant patient. However, in all patients we have described, the clinical
appearance of the lesions only improved slowly over several weeks. As experience with
antibiotics increases it has become apparent that healing is slow but continues long
after the treatment course is completed [18], [19]. Although this is a small clinical
case series of Category I BU, oral rifampicin in combination with clarithromycin or
moxifloxacin shows promise and should be further investigated.
Key Learning Points
Treatment of patients with limited BU prior to surgery using rifampicin-based oral
antibiotics resulted in culture-negative resection specimens.
Clinical healing is slow despite the microbiological activity of oral antibiotics.
Apparent relapses that occur during or after treatment may be due to immunologically
driven paradoxical reactions rather than primary treatment failure.
Rifampicin-based oral antibiotic therapy for the treatment of M. ulcerans infection
followed by delayed surgery appears to simplify management by allowing excision and
closure in one step without relapse.