Streptococcus pneumoniae infection laboratory findings
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Streptococcus pneumoniae infection Microchapters |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Depending on the nature of infection, an appropriate sample is collected for laboratory identification. Pneumococci are typically gram positive, cocci, seen in pairs or chains. When cultured on blood agar plates with added optochin antibiotic disk, they show alpha-hemolytic colonies and a clear zone of inhibition around the disk meaning they're sensitive to the antibiotic. Pneumococci are also bile soluble. Just like other streptococci, it's catalase negative. Quellung test to identify specific capsular polysaccharides may also be done.
Laboratory Diagnosis
Diagnosis is generally made based on clinical suspicion along with a positive culture from a sample from virtually any place in the body. An ASO Titre of >200 units is significant.[1] S. pneumoniae is, in general, optochin sensitive, although optochin resistance has been observed.[2]
Atromentin and leucomelone possess antibacterial activity, inhibiting the enzyme enoyl-acyl carrier protein reductase, (essential for the biosynthesis of fatty acids) in S. pneumoniae.[3]
References
- ↑ Siemieniuk, Reed A.C. (Nov 2011). "The persisting burden of invasive pneumococcal disease in HIV patients: an observational cohort study" (PDF). BMC Infectious Diseases. 11: 314. doi:10.1186/1471-2334-11-314. PMC 3226630. PMID 22078162. Unknown parameter
|coauthors=ignored (help) - ↑ Pikis, A; Campos, JM; Rodriguez, WJ; Keith, JM (2001). "Optochin resistance in Streptococcus pneumoniae: mechanism, significance, and clinical implications". Journal of Infectious Diseases. 184 (5): 582–590. doi:10.1086/322803. PMID 11474432.
- ↑ Zheng CJ, Sohn MJ, Kim WG. (2006). "Atromentin and leucomelone, the first inhibitors specific to enoyl-ACP reductase (FabK) of Streptococcus pneumoniae". Journal of Antibiotics. 59 (12): 808–12. doi:10.1038/ja.2006.108. PMID 17323650.