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Year : 2020  |  Volume : 3  |  Issue : 3  |  Page : 144-146

An unusual case report of Streptococcus mitis causing complex empyema thoracis

1 Department of Respiratory Medicine, Apollo Main Hospitals, Greams Lane, Chennai, Tamil Nadu, India
2 Department of Respiratory Medicine, Sundaram Medical Foundation, Chennai, Tamil Nadu, India

Date of Submission08-Mar-2021
Date of Decision09-Mar-2021
Date of Acceptance10-Mar-2021
Date of Web Publication28-Apr-2021

Correspondence Address:
Ria Lawrence
Department of Respiratory Medicine, Apollo Main Hospital, Greams Lane, Chennai - 600 006, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/japt.japt_9_21

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Empyema is the collection of pus within the pleural space. The most common infective etiology of empyema is the Gram-positive organisms such as Streptococcus pneumonia and Staphylococcus aureus. Streptococcus mitis which is an oral commensal is known to cause serious infections in cancer patients receiving chemotherapy and in immunosuppressed individuals. However, there are very few case reports of S. mitis causing a complex empyema in a middle-aged woman with type 2 diabetes. Here, we discuss the case of a 58-year-old lady, a known case of type 2 diabetes mellitus under regular medication, who presented with complaints of loin pain on the right side for 1 week and breathlessness for 3 days. On evaluation, she had complex empyema on the right side with culture showing S. mitis.

Keywords: Empyema, Streptococcus mitis, streptokinase

How to cite this article:
Lawrence R, Sridhar R, Narasimhan R. An unusual case report of Streptococcus mitis causing complex empyema thoracis. J Assoc Pulmonologist Tamilnadu 2020;3:144-6

How to cite this URL:
Lawrence R, Sridhar R, Narasimhan R. An unusual case report of Streptococcus mitis causing complex empyema thoracis. J Assoc Pulmonologist Tamilnadu [serial online] 2020 [cited 2021 Sep 20];3:144-6. Available from: http://www.japt.com/text.asp?2020/3/3/144/314972

  Introduction Top

Empyema is the collection of pus within the pleural space. Pleural infection is one of the oldest and severest diseases. Drainage of the pleural cavity was attempted by Hippocrates over 2000 years ago to treat empyema. During the influenza pandemic of 1917–1919, closed pleural drainage became widely practiced to treat postpneumonic empyema. Early diagnosis of empyema is crucial to successful treatment, even with appropriate therapeutic attempts, the mortality of patients with empyema is about 15%–20% and higher in immunocompromised patients.[1]

Streptococcus mitis belonging to the Viridans streptococcus group is a Gram-positive coccus, facultative anaerobe, and catalase negative. It is commonly present as a normal commensal of the human oropharynx, skin, and intestinal and genital tracts.[2] However, S. mitis can cause a variety of infectious complications including infective endocarditis, bacteremia, and septicemia. Recently, viridans streptococci have become a major concern in neutropenic patients[3] undergoing chemotherapy, but here, we report a case of complex lung empyema caused by S. mitis in a patient with type 2 diabetes mellitus.

  Case Report Top

A 58-year-old lady admitted with the complaints of loin pain on the right side for 1 week and breathlessness for 3 days. She had no history of fever, chest pain, cough, and hemoptysis. She was a known case of type 2 diabetes mellitus under regular medication. On arrival, she was afebrile, tachypneic at rest with respiratory rate of 38 breaths/min, oxygen saturation of 88% on room air, and hemodynamically stable. On auscultation, she had right-sided crepitations with reduced breath sounds. Arterial blood gas analysis was suggestive of type I respiratory failure. Echocardiogram revealed mild pulmonary arterial hypertension. Her blood investigations revealed neutrophilic leukocytosis with total count of 17,000 (neutrophils – 91%, lymphocytes – 3%, and monocytes – 4%), elevated total bilirubin (2.4 mg/dl), and liver enzymes (SGPT – 201 units/L and alanine aminotransferase – 211 units/L). Chest Xray [Figure 1] revealed Right sided pleural effusion. Chest Computed tomograpghy [Figure 2] revealed right lower lobe consolidation with moderate loculated right pleural effusion with air pockets.
Figure 1: Initial chest X-ray

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Figure 2: Initial computed tomography of the chest

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She was started on empirical antibiotics and oxygen supplementation. Her COVID real-time–reverse transcriptase-polymerase chain reaction of the nasopharyngeal swab was negative. She was intubated in view of severe respiratory distress and hypoxia. On performing bronchoscopy, we found bronchopleural fistula in the right upper lobe and thick purulent endobronchial secretions. At that time, she was not fit enough to undergo a surgery and so an intercostal drain was inserted by our cardiothoracic surgery team, which drained frank pleural pus which on culture and sensitivity grew pan sensitive S. mitis with a colony count of 100,000 colonies. Pleural fluid was negative for GeneXpert Mycobacterium tuberculosis and cytology. We started her on amoxicillin-clavulanic acid based on the antibiotic sensitivity pattern in culture. Streptokinase was injected through the intercostal drainage tube for adhesiolysis. She improved clinically and interval video-assisted thoracoscopic surgery–decortication was done after 2 weeks. She was discharged with the intercostal drainage tube. After 2 months, a repeat chest X-ray [Figure 3] showed an expanded lung.
Figure 3: Chest X-ray after treatment

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  Discussion Top

Empyema thoracis is the collection of pus within the pleural cavity, usually associated with pneumonia but may also develop after thoracic surgery or thoracic trauma.[4] Etiology of the infection depends whether it is community acquired or hospital acquired. Furthermore, comorbidities of the patients need to be taken into consideration. In community-acquired empyema, Gram-positive bacteria are more common, especially Streptococcus species. Gram-negative bacteria have been commonly seen in patients with comorbidities of alcohol abuse, gastroesophageal reflux disease, and diabetes.[4] In hospital-acquired empyema, Staphylococcus aureus and Pseudomonas are more common.[5] In postoperative and posttraumatic empyema S. aureus is the most common agent. Although rare, fungal empyema is associated with high mortality, the most common fungus isolated from empyema is Candida species.[6]

S. mitis, previously known as Streptococcus mitior, is a Gram-positive coccus, facultative anaerobe and catalase negative. It uses a variety of mechanisms to colonize the human oropharynx.[2] These include expression of adhesins, immunoglobulin A proteases and toxins, and modulation of the host immune system. A recent genomic analysis of B6 strain of S. mitis has shown that it shares a majority of virulence factors with its closest relative of the major human pathogen S. pneumonia. Thus, S. mitis seems to walk on a thin line between commensalism and pathogenicity, sometimes impersonating its virulent member pneumococcus as well, by simple microscopy and biochemical tests.[7]

Although S. mitis is known to cause serious infections among neonates, patients on chemotherapy and intravenous drug abusers,[8] it is relatively rare to cause a complex empyema in a middle-aged woman without any underlying immunosuppression. However, it usually responds to the cephalosporin group[9] of antibiotics; in our case, we found that although she improved clinically, she still had persistent loculated empyema for which she was advised surgical decortication.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.


The authors would like to thank the department of microbiology, radiology, and cardiothoracic surgery team, Apollo Hospitals, Chennai.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Brims FJ, Lansley SM, Waterer GW, Lee YC. Empyema thoracis: New insights into an old disease. Eur Respir Rev 2010;19:220-8.  Back to cited text no. 1
Patterson MJ. Streptococcus. In: Baron S, editor. Medical Microbiology. 4th ed. Ch. 13. Galveston (TX): University of Texas Medical Branch at Galveston; 1996.  Back to cited text no. 2
Bochud PY, Calandra T, Francioli P. Bacteremia due to viridans streptococci in neutropenic patients: A review. Am J Med 1994;97:256-64.  Back to cited text no. 3
Garvia V, Paul M. Empyema. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2020.  Back to cited text no. 4
Chen HW, Zheng JQ, Lin TY. Fulminant lobulated lung empyema caused by Pseudomonas aeruginosa. Rev Chilena Infectol 2012;29:114-5.  Back to cited text no. 5
Ko SC, Chen KY, Hsueh PR, Luh KT, Yang PC. Fungal empyema thoracis: An emerging clinical entity. Chest 2000;117:1672-8.  Back to cited text no. 6
Chakraborty B, Banerjee D, Mukherjee DM, Bandyopadhyay S, Roy A, Pal S. Do we know everything about Streptococcus mitis: From alpha to omega? Ann Trop Med Public Health 2018;11:41-3.  Back to cited text no. 7
  [Full text]  
Desai N, Steenbergen J, Katz DE. Antibiotic Resistance of Non-pneumococcal Streptococci and Its Clinical Impact. Antimicrobial Drug Resistance: Clinical and Epidemiological Aspects 2016;2: 791–810.  Back to cited text no. 8
Bui T, Preuss CV. Cephalosporins. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2020.  Back to cited text no. 9


  [Figure 1], [Figure 2], [Figure 3]


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