Fonsecaea compacta

The taxonomic status of F. compacta is uncertain.[10] The debate whether or not F. compacta is a distinct species of Fonsecaea has persisted for years, essentially since it was discovered.[1] Some authors maintain that F. compacta and F. pedrosoi are separate species given small differences in morphology of conidiophores and conidia.[4][5] F. compacta and F. pedrosoi are readily distinguishable from each other.[1] F. compacta is characterized by its compact conidial heads, blunt scars and subglobose to ovoid conidia, while F. pedrosoi has loose conidial heads, prominent scars, and elongated conidia.[1] It was once thought that the two can not be combined into a single species considering there are base substitutions in 48 positions.[5] The two were also found to have identical D1/D2 sequences, a 600 nucleotide domain in a subunit of rDNA.[12] RAPD and RFLP methods were used to investigate genetic variations between these species, however no variations were found.[12] In 2004, scientists from the University of Chiba in Japan found that there is no difference in subunit ribosomal DNA D1/D2 domain sequence between F. pedrosoi and F. compacta, which may indicate that the latter is merely a morphological variation of the first.[13] More recently, several molecular investigations such as restriction fragment length polymorphism (RFLP) of mitochondrial DNA, ribosomal RNA (rRNA), ITS sequence, random amplified polymorphic DNA (RAPD), large subunit (LSU) rRNA D1/D2 domain sequence, and RFLP of small subunit (SSU) rRNA and ITS regions have revealed that F. pedrosoi and F. compacta have few distinctions at the molecular level.[14] and accordingly F. compacta has been considered a morphological variant of F. pedrosoi.[14]

Chromoblastomycosis is distributed worldwide, although it is more common in tropical and subtropical countries.[16] Large numbers of cases have been reported from Madagascar in Africa, Brazil and Japan.[16] Several studies have shown that it is prevalent in several other countries as well like Thailand, Korea, Pakistan.[16] The five types of lesions described by Carrion in chromoblastomycosis are nodules, tumors, plaques, warty lesions.[16] F. compacta is a very rare species, known only from a few clinical collections.[1] A few of these instances include five cases in India from which F. compacta was isolated.[18] One study of F. compacta in India produced an isolation rate of 15%.[18] Another study from Sri Lanka reported isolation of 2 cases of F. compacta.[2] Infection occurs more commonly in males than females, and typically between the ages of 30-50.[16] It is less commonly seen in adolescence, with onset occurring before the age of 20 in 24% of cases.[18][19]

Infection caused by F. compacta is thought to be acquired through the same mechanisms as other more common agents of chromoblastomycosis, such as through puncture wounds caused by wooden splinters or thorny plants which allow the fungus to gain entry.[20] Increased cases are seen in agricultural workers such as adult male farmers and laborers, whose occupation brings them into close contact with soil, are mainly affected.[19] Poverty and malnutrition in Indian children may be responsible for the early development of clinical infection.[18] The Fonsecaea species have been reported to be recoverable from environmental sources and therefore the disease is considered to be of traumatic origin.[4] Nevertheless, the precise natural niche of both F. compacta has remained uncertain and hence it is unclear where and how symptomatic patients have acquired their infection.[4]

Good hygiene and adequate nutrition may help the individual abort a potential infection.[18] Early stages of treatment for minor chromoblastomycosis cases involve surgical excision, electrodesiccation.[16] cryosurgery, physical therapy, using liquid nitrogen for localized lesions is very effective and can be applied in combination with antifungal therapies.[20] More advanced cases require systemic antifungals treatment for extended periods of time.[20] Severe lesions tend to respond slowly or even become non-responding to antifungal drugs.[20] Presently, the most useful antifungals against chromoblastomycosis include itraconazole and terbinafine, which are highly expensive and often used in combination.[16][20] Cure rates observed with antifungal drugs vary from 15 to 80%.[20] In severe forms cure rates are particularly low and relapse rates are high.[20] F. compacta and F. pedrosoi are less susceptible to antifungal treatments so cure rates are lower compared to other agents of the disease.[20]