Primary Cutaneous Nocardial Infection Presenting as Mycetoma: A Case Report with a Short Review of Primary Cutaneous Nocardial Infections in India

1. M.D. (Microbiology) Department of Microbiology, Mamata Medical College, Khammam, AP, India. 2. M.D. (Pathology) Department of Pathology, Mamata Medical College, Khammam, AP, India. 3 M.D. (Microbiology) Department of Microbiology, Mamata Medical College, Khammam, AP, India.

Abstract

Primary cutaneous nocardiosis remains a diagnostic challenge. Here, we are reporting a case of primary cutaneous nocardiosis which was caused by N. brasiliensis and have reviewed the cases of primary cutaneous nocardiosis which have been published in the Indian literature. A 65-year old male patient, a farmer by occupation, came with a history of multiple draining sinuses over the medial aspect of the upper thigh. Gram staining of the discharge showed gram positive branching filamentous bacteria and modified Ziehl-Neelsen’s staining showed acid fast filamentous bacilli. The colonies were small, wrinkled, and dry and they produced an orange yellow coloured pigment. The isolate was identified as N. brasiliensis. The microbiologist as well as treating physician should also have a suspicion of nocardiosis for the early detection of this lesion.

Mycetoma, Nocardia, Primary Cutaneous

Introduction
Primary nocardiosis remains a diagnostic challenge. A majority of the acute nocardial abscesses and lymphocutaneous infections go unsuspected and undiagnosed because of their non-specific clinical picture and the difficulty in isolating the organism. A high index of clinical suspicion is needed for the diagnosis of this condition, along with the stringent efforts of microbiologists, for the isolation this organism (1). The genus, Nocardia comprises of gram positive, aerobic, acid fast and filamentous bacteria. They are found worldwide and are saprophytes of soil, decaying wood, water and air. Nocardia asteroids complex, N. brasiliensis, N. farcinica, and N. nova are commonly implicated for infections in humans. Mycetoma, with the clinical triad of tumefaction, draining sinuses, and granules in the discharging pus, is the characteristic and the most common presentation (2). The incidence and the prevalence of primary cutaneous nocardiosis have not been adequately documented, even in areas where the infection is prevalent (3). Here, we are reporting a case of primary cutaneous nocardiosis which is caused by Nocardia brasiliensis (N. brasiliensis) and have reviewed the cases of primary cutaneous nocardial infections which have been reported from India.

Case Report

65-year old male patient, a farmer by occupation, came to the surgical department with a history of skin lesions over the right thigh since one year. There was diffuse enlargement of the right thigh and multiple draining sinuses over the medial aspect of the upper thigh. These were small nodules to start with, which had become ulcerated (Table/Fig 1). The swelling was tender and warm to touch and there were few puckered scar marks. There was no inguinal lymphadenopathy or bony involvement. A serous discharge was seen to be coming out from some of these lesions. Granules were not seen. The systemic examination was normal. Case Report Microbiology Section The routine haematological investigations and the chest X-ray were within normal limits. Plasma glucose, serum bilirubin, liver enzymes, blood urea and serum creatinine were normal. The discharging pus was collected with two clean and sterile swabs. Gram staining of the discharge was done, which showed gram positive branching filamentous bacteria. Considering the possibility of Nocardia, the slides were stained by Ziehl- Neelsen’s staining and 1% sulfuric acid was used to decolourize the slides; which showed acid fast filamentous bacilli. Another sterile swab with the discharge was inoculated onto blood agar and Sabouraud’s dextrose agar (with and without chloramphenicol) and these media were incubated at 37°C aerobically. Additionally, another blood agar plate was inoculated anaerobically by using the gas pack method, which showed no growth. Growth was seen over blood agar and Sabouraud’s dextrose agar after incubation for 72 hours. The colonies were small, wrinkled, and dry and they produced an orange yellow coloured pigment (Table/Fig 2). We did gram staining and modified acid staining of the isolate (Table/Fig 3). By performing a battery of biochemical tests (urea hydrolysis, hydrolysis of casein, xanthine and tyrosine, growth at 42°C and gelatin hydrolysis), we identified the isolate as N. brasiliensis. The isolates were sensitive to co-trimaxazole, streptomycin, and amikacin. The patient was treated with co-trimaxazole for three months and he showed complete regression of the lesions.

Discussion

Nocardial infections occur worldwide, particularly in the tropical/ sub-tropical environments (2). Although the lungs are the primary organs which are affected by the Nocardia species, cutaneous nocardiosis can also occur as the primary disease in apparently immunocompetant hosts (4). A traumatic inoculation in the skin is the typical mode for acquisition of the primary infection in immunocompetent hosts, resulting in an acute inflammatory response, terminating in necrosis and abscess formation. The cutaneous reported from India (5). The incidence of Nocardial mycetoma was found to vary from 5.2% to 35% in the Indian literature. The exact incidence of primary cutaneous nocardiosis is not clear, as many of these studies have not reported whether these were primary or secondary cases. The data regarding the overall incidence of this infection in India is not available (1),(2),(3),(5). We have analyzed the cases of primary cutaneous nocardiosis that were reported from India in (Table/Fig 4) (5),(6),(7),(8),(9),(10),(11),(12),(13),(14). Mycetoma is a chronic, localized infection of the dermis and the sub-cutaneous tissue, with indolent swelling and draining sinuses. The granules which were discharged were less than 1mm in size and they were yellowish – white (3). The granules in the discharge were actually aggregates of the microcolonies of the organism. More than 20 species of fungi and bacteria have been implicated as the aetiologic agents of mycetoma. N. brasiliensis and N. asteroids account for the infection in a majority of the cases which are caused by Nocardia species and follow the mostly forgotten, traumatic implantation or contamination of a wound which involves the lower limb and the hands in a majority of the cases (2),(3). The other unusual sites of involvement are the scalp, shoulder, and the upper back, which correspond to the usual sites of load carrying in agricultural workers (3). The involvement of the thigh (as is in our case) is not reported frequently. Unlike eumycetoma, these lesions are acute in onset (incubation period of about 2 weeks) and more inflammatory and they are associated with tenderness. Mycetoma, especially when it is caused by N. Brasiliensis, has a propensity to involve the underlying bone, and osteolytic changes are frequently observed radiologically (3),(4).
Diagnosis
Despite the characteristic presenting clinical features, many patients remain undiagnosed for long periods, perhaps for want of clinical suspicion (2). The demonstration of this organism from clinical specimens like granules, pus or aspirated fluid from an unruptured nodule by gram staining and modified Kinyoun staining is the mainstay of the diagnosis. Gram positive and acid fast, thin, beaded, branching filaments are the characteristic appearances of this organism. Identification of the Nocardia species by culture is a tedious process. The organism is slow growing and it may take up to 2-3 weeks for its isolation from a clinical specimen. The small Nocardial colonies are overgrown by other rapidly growing organisms, resulting in an initial negative culture report (3). The role of histopathological examination in its diagnosis is arguable, as many of the studies could not identify the organism in the biopsies, except for the presence of the granulomatous reaction. Rapid and reliable molecular methods, though they are available, are beyond the reach of many investigating laboratories (1). Hence, a good microbiological examination, coupled with culture studies, are helpful for establishing a definitive diagnosis. The timely initiation of an effective treatment is imperative for a favourable outcome. An antibiogram is suggested for all the species which are isolated because of their varied antibiotic sensitivity pattern (3). To conclude, a high degree of clinical suspicion is needed for the diagnosis of Nocardiosis, along with stringent efforts of the microbiologist for isolating the causative organism. The microbiologist as well as treating physician should also have a suspicion of nocardiosis for the early detection of this lesion.

DOI and Others

DOI: JCDR/2012/3717:1982

Financial OR OTHER COMPETING INTERESTS:
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Date of Submission: Jul 19, 2011
Date of Peer Review: Nov 18, 2011
Date of Acceptance: Dec 22, 2011
Date of Publishing: May 01, 2012