A case of Actinomycotic mycetoma involving the right foot

A 45-year-old male presented with history of multiple swellings over the foot with sinuses discharging seropurulent pus. Actinomadura madurae was demonstrated and identified by microbiological culture from the pus obtained directly of the lesion. This case is reported to emphasize the importance of laboratory diagnosis in the management and assessment of the prognosis of such cases.


Introduction
Mycetoma is a chronic subcutaneous infection caused by actinomycetes or fungi.This infection results in granulomatous inflammatory response in the deep dermis and subcutaneous tissue, which can extend to the underlying bone.Mycetoma is characterized by the formation of grains containing aggregates of the causative organisms that may be discharged onto the skin surface through multiple sinuses.Eumycetoma is more common in northern India [1], while actinomycetoma is common in southern India [2][3][4].The tendency of members of the population to walk barefoot, along with predisposing environmental factors for mycetoma including rainfall, temperature, soil and the abundance of thorny sharp vegetable materials which can inoculate etiological agents into the feet, instigate the disease [1][2][3][4][5].This disease has been reported to respond to sulpha drugs, rifampicin, streptomycin and dapsone.

Case Report
A 45-year-old male from eastern Uttar Pradesh was admitted to Sir Sunderlal Hospital, Banaras Hindu University, Varanasi, with history of pain, swelling and discharging sinus in the right foot of fifteen years duration.The initial lesion appeared as a single nodule, which was followed by the appearance of successive nodules close together.The lesions were distributed mainly on the dorsum surface of the foot.All the nodules showed intermittent discharge for which the patient took an analgesic and antibiotic (Ciprofloxacin).This treatment partially relieved the patient of the discharge; however, the nodules persisted.Over the course of one year, the patient experienced severe pain and swelling at the same site necessitating hospitalization.There was a past history of trauma because the patient had been a football player from 1968 to 1986.On examination, the right foot showed swelling and hardened surface skin with multiple discharging nodules (Figure 1).The regional lymph nodes were not enlarged.Gross examination of the discharge revealed yellow granules.An X-ray of the right foot revealed no bony abnormality.The patient history and physical findings at this point were strongly suggestive of mycetoma.Gram stain revealed gram-positive branching filaments, which were narrow and not fragmenting (0.5-1micrometer) in size.Modified Kinyoun's staining with 1% sulphuric acid was found to be negative.Ziehl Neelsen staining was also negative.Non-acid-fast filamentous branching bacteria were strongly suggestive of actinomycotic mycetoma.Simultaneously the sample was inoculated on plain Sabouraud's dextrose agar, 10% sheep blood agar and brain heart infusion broth.Sabouraud's dextrose agar was incubated at 25°C and 37°C and the samples were examined daily.Inoculated blood agar plates were incubated under aerobic and anaerobic conditions.On the tenth day of incubation a growth was seen on blood agar, which was incubated aerobically.The colony was glabrous, waxy, heaped and folded in appearance.The colour of the colony was initially white and later changed to a tan colour.
As anticipated, Gram stain revealed gram-positive branching filaments from the growth (Figure2).The isolate was further identified by standard bacteriological methods.Following culture, biochemical studies were conducted, including hydrolysis of casein, tyrosine, xanthine, gelatin, starch, and urea.Acid formation from lactose, xylose, and cellobiose were performed for definitive identification of these bacteria at species level.

Discussion
Mycetoma is characterized by the formation of grains containing aggregates of the causative organisms that may be discharged onto the skin surface through multiple sinuses.The disease was described in 1842 and initially named madura foot, after the region of Madurai in India where it was first identified."The draining sinuses with the presence of grains are characteristic of etiologic agents, including a variety of bacteria (actinomycotic mycetoma) or fungi (eumycotic mycetoma)".It usually affects the foot, hand and legs with tissues becoming necrosed and swollen after infection [6][7][8][9][10].Actinomadura genus includes three species, Actinomadura madurae, A. pelletieri and A. dassonvillei.The nomenclature of the A. dassonvillei species has now been changed to Nocardiosis dassonvillei.
A. madurae is distinguished from A. pelletieri by its ability to produce acid from cellobiose.It is one of the commonest causes of actinomycotic mycetoma characterized by formation of granules containing branched filaments.The growth rate of Actinomadura is slow.It grows on routine mycological media and under aerobic conditions [11].The clinical characteristics are almost the same regardless of whether the disease is caused by actinomycetes or fungus.
Talwar and Sehgal studied 60 clinically suspected cases of mycetoma.Of the 60 suspected cases, 20 were confirmed by culture and histopathological examination.The feet were found to be affected in 70% of these cases (7).Dogra et al. [10] reported a case of actinomycotic mycetoma in a young female.Diagnosis was made by Gram staining and confirmed by histopathological examination.In the present study, diagnosis was made by Gram staining and confirmed by culture.We report a case of actinomycotic mycetoma from a tertiary health care centre from northern India.The case is reported owing to its rare occurrence as only a few such mycetoma cases have been reported from northern India.Although acinomycotic mycetoma is less common in northern India than eumycetoma mycetoma, Bakhi and Mathur have reported a rising incidence of actinomycotic mycetoma in western Rajasthan due to changes in climatic conditions.They have observed that the ratio of the prevalence of maduromycotic mycetoma to the prevalence of actinomycotic mycetoma has decreased from 4:1 to 1.91:1 during the last five years in western Rajasthan [5].Treatment regimens usually consist of combination therapy.Combination therapy of two or more drugs is often used to prevent resistance to one antibiotic and persistence of the infection.Our patient responded to Dapsone 100 mg 1 tablet OD, Bactrim DS 1 tablet BD and daily Rifampicin 600mg 1 tablet OD for five weeks.Treatment response was assessed after five weeks.The patient showed good progress, with a fair diminution of local pain and nodule size, and treatment was further continued for five months.The lesions have shown definite regression after six months of therapy.Hence the identification of the causative agent and differentiation of eumycotic mycetoma from actinomycotic mycetoma constitute the major points in application of appropriate antimicrobial therapy.The novelty of this case is its unusual geographic presentation in northern India.

Figure 1 .
Figure 1.Photograph of the growths on the right foot.