Pneumococcal infections laboratory findings: Difference between revisions
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{{Pneumococcal infections}} | {{Pneumococcal infections}} | ||
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==Laboratory Findings== | |||
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 [[hemolysis (microbiology)|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]], they are [[catalase]]-negative. A [[Quellung]] test can identify specific capsular polysaccharides.<ref name=Werno>{{cite journal |author=Werno AM, Murdoch DR |title=Medical microbiology: laboratory diagnosis of invasive pneumococcal disease |journal=Clin. Infect. Dis. |volume=46 |issue=6 |pages=926–32 |year=2008 |month=March |pmid=18260752 |doi=10.1086/528798 |url=http://www.journals.uchicago.edu/doi/full/10.1086/528798}}</ref> | |||
Pneumococcal antigen (cell wall C polysaccharide) may be detected in various body fluids. Older detection kits, based on latex agglutination, added little value above Gram staining and were occasionally [[Type I and type II errors|false-positive]]. Better results are achieved with rapid [[immunochromatography]], which has a [[Sensitivity and specificity|sensitivity]] (identifies the cause) of 70-80% and >90% specificity (when positive identifies the actual cause) in pneumococcal infections. The test was initially validated on urine samples, but has been applied successfully to other body fluids.<ref name=Werno/> Chest X-rays can also be conducted to confirm an infection. | |||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
[[Category: | [[Category:Disease]] | ||
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[[Category:Pneumonia]] | |||
[[Category:Bacterial diseases]] | |||
[[Category:Needs overview]] | |||
{{WH}} | {{WH}} | ||
{{WS}} | {{WS}} |
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Laboratory Findings
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, they are catalase-negative. A Quellung test can identify specific capsular polysaccharides.[1]
Pneumococcal antigen (cell wall C polysaccharide) may be detected in various body fluids. Older detection kits, based on latex agglutination, added little value above Gram staining and were occasionally false-positive. Better results are achieved with rapid immunochromatography, which has a sensitivity (identifies the cause) of 70-80% and >90% specificity (when positive identifies the actual cause) in pneumococcal infections. The test was initially validated on urine samples, but has been applied successfully to other body fluids.[1] Chest X-rays can also be conducted to confirm an infection.
References
- ↑ 1.0 1.1 Werno AM, Murdoch DR (2008). "Medical microbiology: laboratory diagnosis of invasive pneumococcal disease". Clin. Infect. Dis. 46 (6): 926–32. doi:10.1086/528798. PMID 18260752. Unknown parameter
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