An unusual cause of fungal pneumonia

Abstract

A 65 year old female, known asthmatic on steroids intermittently, with no other co-morbidity presented with fever, breathlessness and cough with mucoid expectoration of ten days duration with bilateral crepts, went for Type II respiratory failure and was intubated followed by tracheostomy in view of prolonged ventilator support. In spite of high end antibiotics as per sputum culture sensitivity, weaning off the ventilator was not possible. Blood investigations revealed leucocytosis with neutrophilic predominance and I_gE levels were within normal limits. CT chest showed multiple patchy consolidations of the right upper, middle and lower lobes with ground glass appearance and enlarged mediastinal lymph nodes. Work up for retrovirus, tuberculosis and Sputum for KOH mount was negative. No evidence of sputum and blood eosinophilia. BAL sample grew Curvularia species. Fluconazole 150mg OD was added. Serial imaging of the chest showed resolution of the consolidation and was weaned off the ventilator and was comfortable on room air. Pneumonia caused by Curvularia, in an immune competent patient is very rare. Even in broncho pulmonary involvement these fungi usually occur in allergic conditions as in ABPA than appearing as a solitary cause for lung infection. But if diagnosed and treated early, will respond well to triazoles. This case report highlights a unilateral fungal pneumonia with dramatic clinical improvement post treatment once the rare causative organism was identified.

Pneumonia is the leading infectious cause of death in developed countries.[1,2] Among the vast diversity of respiratory pathogens, fungi account for only a small portion of community-acquired and nosocomial pneumonias. However, fungal respiratory infections generate concern in the expanding population of immunosuppressed patients.[1]

Although the common fungal species seen in immuno-compromised patients are Aspergillus spp., Candida spp. and Chrysosporium spp., there has been the emergence of systemic fungal infection caused by fungi with low inherent virulence, such as dematiaceous fungi.[3] Curvularia is a fungus that belongs to a dematiaceous saprophyte commonly found in the soil and plant materials. It rarely causes serious illness in humans. Infection with Curvularia spp. includes mycotic keratitis, black piedra and deep tissue infection.[4] Curvularia deep tissue infection is being recognized more frequently with case reports of invasive sinusitis with extension into the central nervous system, pneumonia, deep sternal wound infections and endocarditis.[4,5] Clinical manifestations include pneumonia, asymptomatic solitary pulmonary nodules, and endobronchial lesions that may cause hemoptysis.

Case Report

The 65-year-old female, known asthmatic on steroids intermittently, with no other co-morbidity presented with fever, breathlessness and cough with a mucoid expectoration of 10 days duration. Bilateral crepts were heard in auscultation. She was maintaining saturating well in room air. Blood investigations revealed leukocytosis with neutrophilic predominance. Absolute eosinophil count and blood IgE levels were within the normal limits. Computed tomography chest showed multiple patchy consolidations of the right upper, middle and lower lobes with ground glass appearance and enlarged mediastinal lymph nodes with predominantly involving the Right lower lobe [Figure 1a–c].

Figure 1.

CT-images showing multiple patchy consolidations in Right upper, middle and lower lobes with ground glass opacities in lower lobe

Work up for retrovirus and tuberculosis was negative. Sputum for KOH mount was negative initially and no evidence of sputum eosinophilia. Sputum gram stain showed Gram-negative bacterial growth, and she was started on antibiotics. Meanwhile, patient went for Type II respiratory failure and was intubated followed by tracheostomy in view of prolonged ventilator support.

In spite of high-end antibiotics as per sputum culture sensitivity, weaning off the ventilator was not possible. Bronchoscopy showed pus along with flakes in the right lateral basal bronchus. Bronchial wash sample grew Curvularia species [Figure 2a and b].

Figure 2.

(a) Black coloured colonies of Curvularia grown in slide culture. (b) Microscopic observation of slide culture: Conidia seen (5’o clock position in left upper quadrant)

Conidia are pale brown, with three or more transverse septa (phragmoconidia) and are formed apically through a pore (poroconidia) in a sympodially elongating geniculate conidiophores. Conidia are cylindrical or slightly curved, with one of the central cells being larger and darker [Figure 3a and b].

Figure 3.

(a) Tube culture (b) Tube culture showing brownish to blackish brown with black reverse fungal colonies

Colonies are fast growing, suede-like to downy, brown to blackish brown with a black reverse.

Curvularia is a dematophyte, ubiquitous in nature and not uncommonly isolated from clinical specimens and air samples in this part of the world. Most isolates have no significance, and it is only when mycelium is seen in the microscopy of clinical material and the same fungus isolated repeatedly, that any significance is given to their isolation. These fungi are readily inhaled from the atmosphere, and this was the most likely source of the infection in our patients.

Treatment

Fluconazole 150 mg OD was added. Serial imaging of the chest showed resolution of the consolidation. She was weaned off the ventilator and was comfortable on room air. Radiological clearance was observed even within 3 weeks of treatment [Figure 4a and b].

Figure 4.

(a) Chest X-ray (CXR) at the time of starting anti-fungals. (b) CXR after 3 weeks of anti-fungals (oral fluconazole - 150 mg/day)

Discussion

The genus Curvularia (filamentous fungi) contains some 35 species that are mostly subtropical and tropical plant parasites. Three ubiquitous species have been recovered from human infections, principally from cases of mycotic keratitis; Curvularia lunata, Callicebus pallescens and C. geniculata. C. lunata is the most commonly encountered species. Importantly, the infections may develop in patients with intact immune system.[6] Clinical manifestations of phaeohyphomycosis include sinusitis, endocarditis, peritonitis and disseminated infection which are more common than pulmonary infections. Even in broncho pulmonary involvement these fungi usually occur in allergic conditions as in Allergic bronchopulmonary aspergillosis (ABPA) than appearing as a solitary cause for lung infection.[7] Hence, this case was reported as the patient admitted had normal allergic markers and no evidence of ABPA.

Pneumonia caused by Curvularia in an immune competent patient is very rare and it is unclear what specific risk factors may contribute to pulmonary infection with these fungi, which are commonly found in the environment. Howeve if diagnosed and treated early, will respond well to first-line drugs like triazoles (fluconazole, varicanazole, itraconazole, posaconazole) and amphotericin B.[8] This case report highlights a unilateral fungal pneumonia with dramatic clinical improvement posttreatment once the rare causative organism was identified.