A Rare Case of Invasive Pulmonary Infection by Syncephalastrum racemosum in a Pulmonary Tuberculosis Patient

ABBREVIATIONS USED IN THIS ARTICLE

AFB = Acid fast bacil; ATT = Antitubercular treatment; MIC = Minimum inhibitory concentration; WBC = White blood cells.

INTRODUCTION

Zygomycosis represents a spectrum of infections caused by ubiquitous fungal pathogens. Syncephalastrum racemosum species belong to the syncephalastrum genus, zygomycetes class and Mucorales order. Antecedently, these fungi were regarded as non-pathogenic to the humans and were contemplated as laboratory contaminants. In the current era, however, these fungi are surging as highly opportunistic pathogens and immunocompromised people per say, patients on steroid therapy for a long term, poorly controlled diabetics, or patients with malignant etiology, patients on treatment with cytotoxic drugs, AIDS, having renal disease, or liver disease (cirrhosis) are the ones affected predominantly. The diseases caused by them can be divided into primarily six types: rhino cerebral, pulmonary, cutaneous, gastrointestinal, isolated renal, and rarely disseminated.¹ Since the species is rare in causing human infections, data obtained on response to various antifungal agents is also sparse. Nevertheless, contemporary evolution in strategies for diagnosis now results in early identification and treatment of the infection. The drug of choice is considered to be amphotericin B with regards to its low minimum inhibitory concentration (MICs).² Here, we are describing a rare case of S. racemosum causing invasive pulmonary infection in a tuberculosis patient.

DISCUSSION

Syncephalastrum is a filamentous fungus which is ubiquitous in the environment and found in soil, mainly in tropical and subtropical areas. The importance of diagnosing fungal infections is increasing as they are emerging in a wide manner in recent years and frequently causing fatal mycotic disease, due to plenty of risk factors, such as use of broad-spectrum antibiotic, empirical antifungal treatment, steroids, aggressive chemotherapies, and sustained leucopenia. Syncephalastrum racemosum is a species that rarely infects humans. A very few cases have been reported in medical literature of this species causing subcutaneous and onychal infections, 1 with intraabdominal infection and less than 5 cases have been reported of invasive pulmonary infection, first by Kirkpatrik M, Rodriguez G, and 2 cases by Irshad M et al.³ These fungi characteristically produce large, ribbon-like branched hyphae that are irregular in diameter with only occasional septae, hence considered as aseptate fungi. They have a peculiar characteristic of producing merosporangia with the spores arranged in a linear series, which could lead to confusion with Aspergillus.⁴ These spores can be seen in the nose, throat, and stool of healthy subjects but in immunocompromised patients, they can cause invasive disease. The pathogen on culture forms colonies which are initially greyish-white and fluffy but later due to sporulation, changes to dark brown color.⁵ Radiologically, it only shows consolidation with rapidly leads to acute respiratory distress syndrome-like picture. The only effective treatment option available as per the data is amphotericin B or posaconazole, although much has not been studied due to its paucity of invasive human infections, and even if diagnosed, being too late to assess the treatment outcomes. Besides this, the prognosis of patient is also determined by the immune status of patients. Coming to our case, bearing in mind, the immune status of patient and recent hospitalization, we anticipated viral pneumonia, fungal infection, atypical and multidrug-resistant bacterial pneumonia, and primary disease progression as the differentials. However, there was a delay in diagnosis till the sputum culture reports were obtained, with so many differentials and diagnostic methods, we still need a high index of suspicion for establishment of clinical significance of such a rare fungal species. Furthermore, more substantial and various studies are needed to form treatment protocols and management strategies for the same.

ORCID

Sheetal Verma https://orcid.org/0000-0001-5741-662X

Sandeep Nain https://orcid.org/0000-0001-7411-9520

REFERENCES

1. Rinaldi MG. Zygomycosis. Infect Dis Clin North Am 1989;3:19–37. PMID: 2647832.

2. Espinel-Ingroff A, Chakrabarti A, Chowdhary A, et al. Multicenter evaluation of MIC distributions for epidemiologic cutoff value definition to detect amphotericin B, posaconazole, and itraconazole resistance among the most clinically relevant species of Mucorales. Antimicrob Agents Chemother 2015;59(3):1745–1750. DOI: 10.1128/AAC.04435-14.

3. Irshad M, Nasir N, Hashmi UH, et al. Invasive pulmonary infection by Syncephalastrum species: Two case reports and review of literature. IDCases 2020;21:e00913. DOI: 10.1016/j.idcr.2020.e00913.

4. Jindal N, Kalra N, Arora S, et al. Onychomycosis of toenails caused by Syncephalastrum racemosum: A rare non-dermatophyte mould. Indian J Med Microbiol 2016;34(2):257–258. DOI: 10.4103/0255-0857.176844.

5. Mangaraj S, Sethy G, Patro MK, et al. A rare case of subcutaneous mucormycosis due to Syncephalastrum racemosum: Case report and review of literature. Indian J Med Microbiol 2014;32(4):448–451. DOI: 10.4103/0255-0857.142252.