An Unusual Case of Thoracic Empyema due to Blastocystis hominis

Rania Imaniar¹ https://orcid.org/0009-0004-7741-8429, Ika P Sari², Diah Handayani³, Aditya Wirawan⁴

^1,3,4Department of Pulmonology and Respiratory Medicine, Faculty of Medicine, Universitas Indonesia, Jakarta; Department of Pulmonology and Respiratory Medicine Staff Group, Universitas Indonesia Hospital, Universitas Indonesia, Depok, Indonesia

²Department of Parasitology, Faculty of Medicine, Universitas Indonesia, Jakarta; Clinical Parasitology Staff Group, Universitas Indonesia Hospital, Universitas Indonesia, Depok, Indonesia

Corresponding Author: Rania Imaniar, Department of Pulmonology and Respiratory Medicine, Faculty of Medicine, Universitas Indonesia, Jakarta; Department of Pulmonology and Respiratory Medicine Staff Group, Universitas Indonesia Hospital, Universitas Indonesia, Depok, Indonesia, Phone: + 62-21-489-3536 e-mail: rania.imaniar02@ui.ac.id

Received: 30 March 2024; Accepted: 27 December 2024; Published on: 17 February 2025

ABSTRACT

Introduction: Blastocystis hominis is a single-celled organism that is usually found in the intestinal tract. Clinical manifestations of B. hominis infection in humans are nonspecific and include diarrhea, abdominal pain, cramps or discomfort, and nausea.

Case description: A 47-year-old male came with a chief complaint of worsened shortness of breath for 2 weeks before being admitted to the hospital. Chest ultrasound showed a large right pleural effusion. We performed thoracocentesis and inserted a chest tube to drain the pus. Lugol staining of the pleural fluid showed the presence of B. hominis. The patient was treated with metronidazole and trimethoprim/sulfamethoxazole (TMP/SMX).

Discussion: B. hominis has an equivocal role among intestinal parasites due to a lack of knowledge regarding its biology and evidence of its pathogenicity. Based on this case, the treatment that we provided produced a good response for the patient, and B. hominis as the cause of the disease can be considered.

Conclusion: Despite it being thought to only infect the intestinal tract, in this case, we found that B. hominis can also be the cause of thoracic empyema. Treatment with metronidazole and TMP/SMX in the patient resulted in the resolution of the disease.

Keywords: Blastocystis, Case report, Empyema, Pleural effusion

How to cite this article: Imaniar R, Sari IP, Handayani D, et al. An Unusual Case of Thoracic Empyema Due to Blastocystis hominis. Indian J Respir Care 2024;13(4):256–258.

Source of support: Nil

Conflict of interest: None

Patient consent statement: The author(s) have obtained written informed consent from the patient for publication of the case report details and related images.

INTRODUCTION

Blastocystis hominis is a single-celled organism that is usually found in the intestinal tract. It can exist in various morphological forms, such as vacuolar, ameboid, granular, cyst, avacuolar, and multivacuolar.¹ The clinical manifestations of B. hominis infection in humans are nonspecific and may include diarrhea, abdominal pain or discomfort, and nausea. It can also cause fever, fatigue, hepatomegaly, splenomegaly, skin rash, and itching. The clinical manifestation may not be limited to the intestinal tract.¹^,² In this report, we present a case of thoracic empyema due to B. hominis.

CASE DESCRIPTION

A 47-year-old male came with a chief complaint of worsened shortness of breath for 2 weeks before getting admitted to the hospital. He also felt right chest pain, especially when coughing. He had a cough with foul-smelling greenish sputum, fever, weight loss, and shortness of breath for 3 months. He is an active smoker and works as a motorcycle taxi driver.

The physical examination revealed that the patient was underweight, had tachycardia, and hypoxemia. On chest examination, we found decreased right lung sounds with ronchi on both sides. Chest X-ray revealed inhomogeneous consolidation in the right lung field (Fig. 1). We found a large right pleural effusion on chest ultrasound. After thoracocentesis, we found that the pleural fluid was thick, brownish-white in color, and foul-smelling. We then decided to insert a chest tube to drain the pus.

Figs 1A to C: (A) Chest X-ray at first admission showing inhomogeneous consolidation on right lung field; (B) Chest X-ray after chest tube insertion; (C) After 19 days, the right lung has fully expanded

Complete blood count showed leukocytosis (13,770 cells/µL) with neutrophilia. Pleural fluid analysis revealed empyema with high cell counts (12,280 cells/µL), predominance of polymorphonuclear cells, low glucose content, and elevated protein and LDH ratios compared to the serum. Lugol staining of the pleural fluid showed the presence of B. hominis. We decided to treat the patient with metronidazole and trimethoprim/sulfamethoxazole (TMP/SMX). We also administered levofloxacin, as we thought it could be a mixed infection with bacteria. However, after the pleural fluid culture showed no growth of bacteria, we discontinued it. We did HIV and diabetes mellitus screening of the patient, but both turned out to be negative. The sputum GeneXpert testing did not detect Mycobacterium tuberculosis.

Chest and abdominal computed tomography (CT) after chest tube insertion showed right hydropneumothorax with pleural thickening, consolidation of both lungs with air bronchogram, consistent with pneumonia (Fig. 2). No radiological abnormality was seen in the abdominal CT. Nineteen days after chest tube insertion, the lung had fully expanded (Fig. 1A 1 C), the chest tube drain was clear and minimal, and the patient was discharged from the hospital.

Fig. 2: Chest CT showed right hydropneumothorax with pleural thickening, consolidation of both lungs

DISCUSSION

B. hominis is a ubiquitous, single-celled organism that can be found in the intestinal tract.² It is taxonomically classified within the diverse group of Stramenopiles.² It is transmitted via direct and indirect fecal-oral routes.¹^,² There has been controversy about whether this organism is a pathogen or commensal in humans.³ The epidemiology of B. hominis infection varies depending on the subject population and the diagnostic method used to detect B. hominis.⁴^,⁵ The prevalence ranges from 0.14% in an epidemiological study conducted in Poland using microscopic examination to 100% in a study conducted in children in Senegal using PCR as the mode of detection.⁴^,⁵

The risk factors of Blastocystis infections are not washing hands after using the toilet, malnutrition, low immune status, female sex, and raising poultry or livestock.⁶^,⁷Blastocystis infection usually includes gastrointestinal symptoms such as diarrhea, abdominal discomfort, anorexia, flatus, and nausea. It can also cause fever, fatigue, hepatomegaly, splenomegaly, skin rash, and itching.¹^,² In this case, our patient did not have gastrointestinal symptoms but presented with respiratory symptoms and fever that turned out to be right thoracic empyema. We detected B. hominis from the pleural fluid. To our knowledge, infection of B. hominis causing thoracic empyema has not been reported before.

Extraintestinal infection caused by B. hominis has been reported in infective arthritis. The patient was immunocompromised due to prednisone therapy for rheumatoid arthritis, had acute diarrhea, and B. hominis was found in the synovial fluid. In the recent case, our patient did not have gastrointestinal complaints but had low nutritional status. The factors influencing the pathogenicity of Blastocystis infection are parasite abundance, the host’s immune status, genetic variations of the parasite, treatment measures, and other interactions between the parasite and the host.²

The presence of B. hominis >5 per oil immersion field (1000 times) has been linked to acute onset of symptoms.⁸ There is a significant association between B. hominis and the presence of symptoms in immunocompromised individuals. Thirty-four genetic subtypes (ST) of Blastocystis have been identified, with 14 found in humans. However, ST1–ST4 account for over 90% of human infections.⁹ In this case, we cannot identify the subtype because we only did microscopic examination. Based on the findings, we decided to treat the patient with metronidazole and TMP/SMX. Metronidazole is the most commonly prescribed antibiotic for Blastocystis infection. It may be used in combination with other medications, including TMP/SMX or paromomycin, ketoconazole, pentamidine, iodoquinol, tinidazole, and ornidazole.¹⁰ In our case, we used a combination of metronidazole and TMP/SMX for 14 days. After the treatment, the symptoms resolved, and the patient was discharged from the hospital.

B. hominis has an equivocal role among intestinal parasites due to limited understanding of its biology and insufficient evidence of its pathogenicity. Although there are still many questions that cannot be answered, based on this case, the treatment that we provided produced a good response for the patient, and B. hominis as the cause of the disease can be considered.

CONCLUSION

We present a case of thoracic empyema caused by B. hominis. Despite it being thought to only infect the intestinal tract, in this case, we found that B. hominis can also be the cause of thoracic empyema. Treatment with metronidazole and TMP/SMX in the patient resulted in the resolution of the disease.

Clinical Significance

Our patient came with a large pleural effusion that turned out to be thoracic empyema. Parasites are one of the organisms that must be considered as one of the possible pathogens. Clinical manifestations of B. hominis usually involve intestinal symptoms. Extraintestinal manifestation of B. hominis infection is a very rare presentation of the disease.

ORCID

Rania Imaniar https://orcid.org/0009-0004-7741-8429

REFERENCES

1. Stenzel DJ, Boreham PF. Blastocystis hominis revisited. Clin Microbiol Rev 1996;9(4):563–584. DOI: 10.1128/CMR.9.4.563

2. Stensvold CR, Nielsen HV, Mølbak K, et al. Pursuing the clinical significance of Blastocystis—diagnostic limitations. Trends Parasitol 2009;25(1):23–29. DOI: 10.1016/j.pt.2008.09.010

3. Roberts T, Stark D, Harkness J, et al. Update on the pathogenic potential and treatment options for Blastocystis sp. Gut Pathog 2014;6:17. DOI: 10.1186/1757-4749-6-17

4. Kasprzak J, Szaładzińska B, Smoguła M, et al. Intestinal parasites stool samples and perianal swabs examined by The Voivodeship Sanitary-Epidemiological Station in Bydgoszcz between 2000–2014 in. Przegl Epidemiol 2017;71(1):45–54.

5. El Safadi D, Gaayeb L, Meloni D, et al. Children of Senegal river basin show the highest prevalence of Blastocystis sp. ever observed worldwide. BMC Infect Dis 2014;14:164. DOI: 10.1186/1471-2334-14-164

6. Li XX, Chen JX, Wang LX, et al. Intestinal parasite co-infection among pulmonary tuberculosis cases without human immunodeficiency virus infection in a rural county in China. Am J Trop Med Hyg 2014;90(1):106–113. DOI: 10.4269/ajtmh.13-0426

7. Gong B, Liu X, Wu Y, et al. Prevalence and subtype distribution of Blastocystis in ethnic minority groups on both sides of the China-Myanmar border, and assessment of risk factors. Parasite 2019;26:46. DOI: 10.1051/parasite/2019046

8. Kain KC, Noble MA, Freeman HJ, et al. Epidemiology and clinical features associated with Blastocystis hominis infection. Diagn Microbiol Infect Dis 1987;8(4):235–244. DOI: 10.1016/0732-8893(87)90055-1

9. Rudzińska M, Sikorska K. Epidemiology of Blastocystis infection: a review of data from Poland in relation to other reports. Pathogens 2023;12:1050. DOI: 10.3390/pathogens12081050

10. Moghaddam DD, Ghadirian E, Azami M. Blastocystis hominis and the evaluation of efficacy of metronidazole and trimethoprim/sulfamethoxazole. Parasitol Res 2005;96(4):273–275. DOI: 10.1007/s00436-005-1363-1

________________________
© The Author(s). 2024 Open Access. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by-nc/4.0/), which permits unrestricted use, distribution, and non-commercial reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.