STREPTOCOCCUS VIRIDANS , NOT ALWAYS A CONTAMINANT, NOT ALWAYS A COMMENSAL

Shahrzad Shidfar, MD*, University of Massachusetts, Worcester, MA and Katarina Anderson, UMASS medical school, Worcester, MA

Meeting: Hospital Medicine 2017, May 1-4, 2017; Las Vegas, Nev.

Abstract number: 722

Categories: Adult, Clinical Vignette Abstracts

Case Presentation: A 75 year-old man presented with one week of worsening altered mental status and recurrent falls. He also reported dyspnea, non-productive cough and chills of similar duration.  He had history of DM2 well controlled on glipized.  Upon presenation his temperature was 37.8 C, pulse of 94 beats per minute, O2 saturation of 85% on room air and 91% on 2 L oxygen via nasal canula.  Coarse crackles were auscultated in the right lung base. White blood cell count of 16.5 per millimeter cubed with a bandemia of 15%.  Chest x-ray revealed an infiltrate in the base of his right lung. He was started on Ceftriaxone and azithromycin intravenously for presumptive diagnosis of community acquired pneumonia(CAP).  However, blood cultures  revealed Strptococcus mitis and Streptococcus salivarius within 10-15 hours from when drawn first in all 4  bottles which were sensitive to ceftraixone. Transthoracic and transesophageal echo didn’t reveal any vegetations or valvular abnormalities. Computed tomography scan of abdomen and pelvis showed bilateral renal cysts. His last colonoscopy 3 years ago was normal. Head Computed tomography scan was unremarkable. Patient was continued on intravenous ceftraixone to complete 4week course for high grade strep mitis and salivarius bacteremia , possible endocarditis, presumably due to pneumonia caused by these organisms.  Discussion: Streptococcus mitis and streptococcus salivarius are members of the viridans group of streptococci. Viridans group streptococci are considered as a part of the normal oropharynx microbiome. Strep viridans is a well accepted etiologic organism causing infective endocarditis which is often caused by damage to the oral mucosa sustained during dental work. Our patient had no such history, in fact, he had full dentures and on examination of his oral cavity, there were no identifiable lesions.  Traditionally, infectious disease experts do not consider the Strep viridans group as being causal organisms of CAP.   However, in the last decade several case reports questioning this school of thought have been published suggesting that pneumonia caused by the viridans group may not be as rare as previously believed.  In our patient the only culprit of strep viridans bacteremia was his community acquired pneumonia. The majority of the strains are suceptible to penicillin , however 17% of viridans streptococci are moderaetly resistant to pencillin and might require higher concentration of antibiotic or combination therpay for inhibition and killing of resistant strains.

Conclusions: Viridanse streptococci may be a more important casue of community acquired pneumonia than previously thought. The organism should be considered as a possible casue of chest infection, particulary in patients with appropriatly positive blood culturs and no other positive microbiological finsding.

To cite this abstract:

Shidfar, S; Anderson, K . STREPTOCOCCUS VIRIDANS , NOT ALWAYS A CONTAMINANT, NOT ALWAYS A COMMENSAL. Abstract published at Hospital Medicine 2017, May 1-4, 2017; Las Vegas, Nev. Abstract 722. Journal of Hospital Medicine. 2017; 12 (suppl 2). https://www.shmabstracts.com/abstract/streptococcus-viridans-not-always-a-contaminant-not-always-a-commensal/. Accessed September 19, 2019.

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