Buruli ulcer (BU), or Mycobacterium ulcerans infection, is a new emerging infectious disease which has been reported in over 33 countries worldwide. It has been noted not only in tropical areas, such as West Africa where it is most endemic, but also in moderate non-tropical climate areas, including Australia and Japan. Clinical presentation starts with a papule, nodule, plaque or edematous form which eventually leads to extensive skin ulceration. It can affect all age groups, but especially children aged between 5 and 15 years in West Africa. Multiple-antibiotic treatment has proven effective, and with surgical intervention at times of severity, it is curable. However, if diagnosis and treatment is delayed, those affected may be left with life-long disabilities. The disease is not yet fully understood, including its route of transmission and pathogenesis. However, due to recent research, several important features of the disease are now being elucidated. Notably, there may be undiagnosed cases in other parts of the world where BU has not yet been reported. Japan exemplifies the finding that awareness among dermatologists plays a key role in BU case detection. So, what about in other countries where a case of BU has never been diagnosed and there is no awareness of the disease among the population or, more importantly, among health professionals? This article will revisit BU, reviewing clinical features as well as the most recent epidemiological and scientific findings of the disease, to raise awareness of BU among dermatologists worldwide.

Buruli ulcer is a chronic skin disease caused by Mycobacterium ulcerans, which produces a toxic lipid mycolactone. Despite the extensive necrosis and tissue damage, the lesions are painless. This absence of pain prevents patients from seeking early treatment and, as a result, many patients experience severe sequelae, including limb amputation. We have reported that mice inoculated with M. ulcerans show loss of pain sensation and nerve degeneration. However, the molecules responsible for the nerve damage have not been identified. In order to clarify whether mycolactone alone can induce nerve damage, mycolactone A/B was injected to footpads of BALB/c mice. A total of 100 g of mycolactone induced footpad swelling, redness, and erosion. The von Frey sensory test showed hyperesthesia on day 7, recovery on day 21, and hypoesthesia on day 28. Histologically, the footpads showed epidermal erosion, moderate stromal edema, and moderate neutrophilic infiltration up to day 14, which gradually resolved. Nerve bundles showed intraneural hemorrhage, neutrophilic infiltration, and loss of Schwann cell nuclei on days 7 and 14. Ultrastructurally, vacuolar change of myelin started on day 14 and gradually subsided by day 42, but the density of myelinated fibers remained low. This study demonstrated that initial hyperesthesia is followed by sensory recovery and final hypoesthesia. Our present study suggests that mycolactone directly damages nerves and is responsible for the absence of pain characteristic of Buruli ulcer. Furthermore, mice injected with 200 g of mycolactone showed pulmonary hemorrhage. This is the first study to demonstrate the systemic effects of mycolactone.

We describe the fourth reported case involving “ Mycobacterium ulcerans subsp. shinshuense .” Compared to previous cases, the infection was more invasive with extensive ulceration from the elbow to the forearm. Definitive identification involved IS 2404 detection, 16S rRNA gene sequencing, and analysis of the 16S rRNA gene 3′-terminal region and the virulence plasmid pMUM001.

The etiology, clinical manifestations, and treatment of 19 sporadic cases of Buruli ulcer (BU) in Japan are described. The cases originated in different regions of Honshu Island, with no evidence of patient contact with an aquatic environment. The majority (73.7%) of cases occurred in females, with an average age of 39.1 years for females and 56.8 years for males. All patients developed ulcers on exposed areas of the skin (e.g., face, extremities). Most ulcers were <5 cm in diameter (category I), except in one severe progressive case (category II). Pain was absent in 10 of the 19 cases. Fourteen ulcers were surgically excised, and nine patients needed skin grafting. All cases were treated with various antibiotic regimens, with no reported recurrences as of March 2011. Mycobacterium ulcerans-specific IS2404 was detected in all cases. Ten isolates had identical 16S rRNA gene sequences, which were similar to those of M. ulcerans. However, the rpoB gene showed a closer resemblance to Mycobacterium marinum or Mycobacterium pseudoshottsii. PCR identified pMUM001 in all isolates but failed to detect one marker. DNA-DNA hybridization misidentified all isolates as M. marinum. The drug susceptibility profile of the isolates also differed from that of M. ulcerans. Sequence analysis revealed "Mycobacterium ulcerans subsp. shinshuense" as the etiologic agent of BU in Japan. Clinical manifestations were comparable to those of M. ulcerans but differed as follows: (i) cases were not concentrated in a particular area; (ii) there was no suspected connection to an aquatic environment; (iii) drug susceptibility was different; and (iv) bacteriological features were different.

Seven body polishers working in the same "hot spa" presented with multiple red nodules and papules on their hands and forearms. A causative agent was successfully isolated from two of the subjects and from a swab sample collected from the underside of a bed cover in the body-polishing facility. The two cutaneous isolates and the environmental isolate were rapidly growing mycobacteria that formed nonphotochromogenic smooth or smooth/rough colonies on Ogawa egg slants. They were identified as Mycobacterium massiliense by multigenotypic analysis using the 16S rRNA, hsp65, and rpoB genes and the 16S-23S rRNA internal transcribed spacer (ITS) region. However, the use of the 16S rRNA gene sequence and/or DNA-DNA hybridization (DDH Mycobacteria Kit) alone would not distinguish M. massiliense from mycobacteria in the M. chelonae-M. abscessus group. The three isolates were significantly more susceptible to clarithromycin, doxycycline, and minocycline than the M. abscessus and M. bolletii reference strains. One cutaneous isolate and the environmental isolate were in a related cluster by randomly amplified polymorphic DNA PCR (RAPD-PCR). Of the several mycobacterial species found in the day spa, only M. massiliense was isolated from biopsy specimens of the skin lesions, suggesting that this bacterium is a human skin pathogen. This is the first known report of cutaneous M. massiliense infections that could not be attributed to a prior invasive procedure. This is also the first report of M. massiliense infection in Japan.Mycobacterium massiliense was initially isolated from the sputum of a patient with pneumonia in France in 2004 (1). Epidemiologically, M. massiliense has been recognized as an emerging pathogen in the United States (16,24) and Brazil, where outbreaks have been associated with postsurgical and cosmetic procedures (2, 4, 22). In Korea, an outbreak was linked to intramuscular injections of an antimicrobial agent (9). This bacterium was also the source of a lethal case of sepsis in Italy and has been found in cystic fibrosis patients in France (15,20). Among pulmonary M. abscessus group isolates, almost half of the isolates in Korea and 30% of those in the Netherlands are M. massiliense (8,21). It has been suggested that M. massiliense should be reclassified taxonomically as a subspecies of M. abscessus (11). The clinical significance of differentiating these two species has also been explored (7). However, M. massiliense has not been fully characterized. Although mycobacteria are a frequent source of dermal infection, M. massiliense has never been reported as an etiological agent. This report describes the first case of an M. massiliense dermal infection in Japan. Case ReportsIn November 2007, a 49-year-old female who worked as a body polisher in a hot spa developed multiple red nodules and papules on her hands and forearms. The number of lesions gradually increased over several months, precipitating a visit to a local hospital in June 2008 (case 1). A skin biopsy specimen of a nodule stained with hematoxylin a...

The rapidly growing mycobacterium M. abscessus sensu lato is the causative agent of emerging pulmonary and skin diseases and of infections following cosmetic surgery and postsurgical procedures. M. abscessus sensu lato can be divided into at least three subspecies: M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. abscessus subsp. bolletii. Clinical isolates of rapidly growing mycobacteria were previously identified as M. abscessus by DNA-DNA hybridization. More than 30% of these 117 clinical isolates were differentiated as M. abscessus subsp. massiliense using combinations of multilocus genotyping analyses. A much more cost-effective technique to distinguish M. abscessus subsp. massiliense from M. abscessus subsp. abscessus, a multiplex PCR assay, was developed using the whole-genome sequence of M. abscessus subsp. massiliense JCM15300 as a reference. Several primer sets were designed for single PCR to discriminate between the strains based on amplicons of different sizes. Two of these single-PCR target sites were chosen for development of the multiplex PCR assay. Multiplex PCR was successful in distinguishing clinical isolates of M. abscessus subsp. massiliense from samples previously identified as M. abscessus. This approach, which spans whole-genome sequencing and clinical diagnosis, will facilitate the acquisition of more-precise information about bacterial genomes, aid in the choice of more relevant therapies, and promote the advancement of novel discrimination and differential diagnostic assays. bolletii, and that a new subspecies, M. abscessus subsp. abscessus, should be designated (9). However, a recent whole-genome study strongly supported the hypothesis that the species can be divided into at least three subspecies: M. abscessus subsp. abscessus, M. abscessus subsp. massiliense, and M. abscessus subsp. bolletii (10). M. abscessus subsp. massiliense was initially isolated from the sputum of a patient with pneumonia in France in 2004 (5). In 2005, an outbreak of M. abscessus subsp. massiliense infection was linked to intramuscular injections of an antimicrobial agent in South Korea (11). This bacterium was also the source of a lethal case of sepsis in Italy (12) and has been found in cystic fibrosis patients in France (13). Several cases of bacteremia and cutaneous pulmonary infections have also been reported in Japan (14-17).A novel approach is required to differentiate M. abscessus subsp. massiliense from M. abscessus subsp. abscessus and M. abscessus subsp. bolletii because conventional methods such as biochemical assays and 16S rRNA genotyping cannot make the discrimination. Moreover, the clinical profile of M. abscessus subsp. massiliense is different from those of M. abscessus subsp. abscessus and M. abscessus subsp. bolletii. In particular, antibiotic treatment with clarithromycin is more effective against M. abscessus subsp. massiliense lung infections, with resistance developing more readily in cases of M. abscessus subsp. abscessus lung disease. Therefore, differentiating ...

Buruli ulcer (BU) is a new emerging disease and the third most common chronic mycobacterial infection in humans, caused by Mycobacterium ulcerans. Approximately 5000 cases are reported annually from at least 33 countries around the globe, but more from the tropical nations. A total of 32 cases have been reported from Japan sporadically since 1980. None of the cases were related to international travel. Of the total reported, M. ulcerans ssp. shinshuense, a subspecies speculated to be domestic to Japan or in Asia, has been isolated from 23 cases. The mode of transmission and its incubation period remain unclear, despite several proposed hypotheses, including several vectors and cutaneous wound as port of entry for the pathogen. M. ulcerans invades the skin, subcutaneous tissue, fascia and eventually forms extensive ulceration. Smear, culture, histopathology and polymerase chain reaction are established diagnostic tools to identify M. ulcerans. Multiple antimicrobial therapy is a commonly used therapeutic method, but patients often need extensive debridement and, at times, skin grafting, especially when diagnosis is delayed. Thus, expanding a system for improved awareness and diagnosis in Japan and Asia is important, together with elucidating the candidate vector and the mode of transmission. Here, to establish a base for future progress in better understanding of this infectious disease, we reviewed the characteristics of the disease together with an update of reported cases in Japan.

Buruli ulcer is an emerging chronic painless skin disease found in the tropics and caused by Mycobacterium ulcerans; however, it remains unknown why the large and deep ulcers associated with this disease remain painless. To answer this question, we examined the pathology of BALB/c mice inoculated in the footpads with M. ulcerans African strain 97-107. On days 54 to 70 after inoculation, extensive dermal ulcers, subcutaneous edema, and numerous acid-fast bacilli were noted at the inoculate region. Nerve invasion occurred in the perineurium and extended to the endoneurium, and some nerve bundles were swollen and massively invaded by acid-fast bacilli. However, Schwann cell invasion, a characteristic of leprosy, was not observed. Vacuolar degeneration of myelin-forming Schwann cells was noted in some nerves which may be induced by mycolactone, a toxic lipid produced by M. ulcerans. Polymerase chain reaction analysis of microdissected nerve tissue sections showed positive amplification of M. ulcerans-specific genomic sequences but not of Mycobacterium leprae-specific sequences. Behavioral tests showed decrease of pain until edematous stage, but markedly ulcerated animals showed ordinary response against stimulation. Our study suggests that the painlessness of the disease may be partly due to intraneural invasion of bacilli. Further studies of nerve invasion in clinical samples are urgently needed.