International Journal of Infectious Diseases
Volume 12, Issue 6 , Pages e107-e109, November 2008

Community-acquired Streptococcus mitis meningitis: a case report

  • Selda Sayin Kutlu

      Affiliations

    • Department of Infectious Diseases and Clinical Microbiology, Faculty of Medicine, Pamukkale University, Kinikli, 20070 Denizli, Turkey
    • Corresponding Author InformationCorresponding author. Tel.: +90 258 2118585 (2293); fax: +90 258 2410040.
    • ,
  • Suzan Sacar

      Affiliations

    • Department of Infectious Diseases and Clinical Microbiology, Faculty of Medicine, Pamukkale University, Kinikli, 20070 Denizli, Turkey
    • ,
  • Nural Cevahir

      Affiliations

    • Department of Microbiology and Clinical Microbiology, Faculty of Medicine, Pamukkale University, Kinikli, Denizli, Turkey
    • ,
  • Huseyin Turgut

      Affiliations

    • Department of Infectious Diseases and Clinical Microbiology, Faculty of Medicine, Pamukkale University, Kinikli, 20070 Denizli, Turkey

Received 27 April 2007; received in revised form 26 October 2007; accepted 5 January 2008. published online 31 March 2008.

Corresponding Editor: J. Peter Donnelly, Nijmegen, The Netherlands

Article Outline

Summary 

Background

Streptococcus mitis is prevalent in the normal flora of the oropharynx, the female genital tract, gastrointestinal tract, and skin. Although it is usually considered to have low virulence and pathogenicity, Streptococcus mitis may cause life-threatening infections, particularly endocarditis. Meningitis with S. mitis is rare, but has been described in individuals with previous spinal anesthesia, neurosurgical procedure, malignancy, or neurological complications of endocarditis.

Case report

A 58-year-old, alcoholic male patient with a high fever, headache, and changes in mental status was admitted to hospital with the diagnosis of meningitis. S. mitis, isolated from cerebrospinal fluid, was sensitive to penicillin. He was given a 14-day course of ampicillin and made a full clinical recovery.

Conclusions

The purpose of this report is to emphasize the importance of the occurrence of S. mitis meningitis in patients with concomitant factors such as older age (>50 years), alcoholism, poor oral hygiene, and maxillary sinusitis.

Keywords: Streptococcus mitis, Community-acquired meningitis, Older age (>50 years), Alcoholism, Poor oral hygiene

 

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Introduction 

Streptococcus mitis, an important member of the viridans streptococci and a normal part of the oropharynx, skin, gastrointestinal system, and female genital system flora, is a bacterium with low pathogenicity and virulence.1, 2, 3, 4, 5 However viridans streptococci are the most common cause of subacute bacterial endocarditis.3 S. mitis causes severe clinical conditions including sepsis and septic shock especially in neutropenic patients.4, 6 Meningitis with S. mitis is rare, but has been described in individuals with previous spinal anesthesia, neurosurgical procedure, malignancy, or neurological complications of endocarditis, and in newborns.2, 3, 7, 8, 9, 10, 11, 12 We report herein an unusual case of S. mitis meningitis in a man with a history of alcoholism, poor oral hygiene, and maxillary sinusitis.

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Case report 

A 58-year-old alcoholic male was admitted to the emergency department of our hospital with symptoms and signs of meningitis. He had had no recent dental treatment and had periodontitis and poor oral hygiene including dental caries and tongue plaque. The patient presented with a high fever (39°C), headache, and confusion. He had no nuchal rigidity but had a positive Kernig's sign. Laboratory tests revealed the following: hemoglobin 13.26g/dl, hematocrit 40%, white blood cell count 15.4×109/l (83% neutrophils, 12% lymphocytes, and 5% monocytes), platelet count 177×109/l, alanine aminotransferase 20IU/l, aspartate aminotransferase 30IU/l, gamma-glutamyl transpeptidase 34U/l, alkaline phosphatase 49IU/l, direct bilirubin 0.3mg/dl, indirect bilirubin 0.7mg/dl, total protein 6g/dl, and albumin 3.1g/dl. Lumbar puncture yielded cloudy cerebrospinal fluid (CSF) containing 600×106cells/l with 85% neutrophils. The CSF glucose level was 48mg/dl (concomitant blood glucose 121mg/dl) and protein level was 178mg/dl. A computed tomography scan of the brain revealed maxillary sinusitis.

The empiric antibiotic treatment for patients of older age (>50 years) and having a history of alcoholism was initiated: ceftriaxone 4g/day and ampicillin 12g/day IV to cover Listeria monocytogenes also. All the results of the blood cultures were negative. Alpha-hemolytic streptococcus was found in CSF culture. The isolate was identified by standard criteria, on the basis of colony morphology, Gram stain, optochin test, bile esculin, growth 6.5% NaCl, and catalase reaction. S. mitis identification was initially performed using the API 20 STREP (bioMerieux). The identification was also confirmed by conventional biochemical tests (arginine dihydrolase, hippurate hydrolysis, esculin hydrolysis, acetoin production, urease, acid production from mannitol, inulin, maltose, sorbitol, glucose, lactose, sucrose).3 Antibiotic sensitivity was studied according to Clinical and Laboratory Standards Institute (CLSI) criteria.13 Because it was determined to be sensitive in vitro to penicillin (minimum inhibitory concentration ≤0.12μg/ml), treatment was continued with ampicillin. Echocardiography showed no evidence of vegetations or valve pathology. On the fourth day of follow-up, the CSF was reexamined and the measurements were as follows: clear appearance, normal pressure, leukocyte count of 10×106/l, protein 72mg/dl, glucose 82mg/dl (concomitant blood glucose level 109mg/dl). No bacteria were isolated from the CSF. The patient's treatment lasted 14 days and he was totally cured at discharge.

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Discussion 

S. mitis and other viridans streptococci are the agents of numerous infections, primarily of subacute bacterial endocarditis and upper respiratory tract infections.3, 4 Oral hygiene and dental treatment have an important role in bacteremia and following endocarditis.5 Although the patient's blood cultures were negative, in our opinion poor oral hygiene was the probable cause of the bacteremia. It is probable that the viridans streptococci had initially caused the above-mentioned focal infections like sinusitis, which are well known predisposing factors that increase the risk of bacterial meningitis.14 In the present case there was established maxillary sinusitis, which can be the source of meningitis. However, in a third of these meningitis cases the exact source of infection is not clear.15

In pneumonias caused by S. mitis the underlying factors are old age, diabetes, alcoholism, lung cancer, and hypothyroidism.16 We speculate that older age (>50 years) and alcoholism were the predisposing conditions in the development of meningitis in our patient. To our knowledge, this is the first description of S. mitis meningitis with co-morbidities like older age (>50 years) and alcoholism.

Streptococcal meningitis except that caused by Streptococcus pneumoniae, might develop secondary to brain abscess. In these cases peptostreptococci or Streptococcus milleri are generally isolated. Brain abscesses and meningitis might develop also in infective endocarditis. If anaerobic streptococci and other streptococci including S. milleri are isolated in community-acquired meningitis, physicians should examine brain abscess, and if viridans streptococci are isolated he/she should look for infective endocarditis.7 We evaluated our patient for the presence of infective endocarditis, and echocardiography showed that there was no vegetation or valve disease.

Viridans streptococci have become increasingly resistant to antibiotics including penicillin, cephalosporin, erythromycin, and tetracycline. S. mitis is more resistant to antibiotics than other viridans streptococci.1, 3, 6 Viridans streptococci can transfer their resistant genes to more pathogenic pneumococci and group A streptococci.6 The subtype isolated in our case was sensitive to penicillin.

Although S. mitis is believed to be a rare cause of meningitis in the community, it should be considered in the differential diagnosis of this disorder, especially in patients having different accompanying factors such as older age (>50 years), alcoholism, poor oral hygiene, and maxillary sinusitis.

Conflict of interest: No conflict of interest to declare.

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References 

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PII: S1201-9712(08)00033-7

doi:10.1016/j.ijid.2008.01.003

International Journal of Infectious Diseases
Volume 12, Issue 6 , Pages e107-e109, November 2008

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