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Streptococcus pneumoniae can be differentiated from the viridans streptococci, some of which are also alpha-hemolytic, using an optochin test, as S. pneumoniae is optochin-sensitive. S. pneumoniae can also be distinguished based on its sensitivity to lysis by bile, the so-called "bile solubility test".
For decades, Streptococcus pneumoniae has been considered susceptible to optochin; but some strains have been found to be resistant to optochin in laboratory testing. This is notable because the emergence of optochin-resistant strains would invalidate the distinguishing test described above. [3]
Viridans streptococci can be differentiated from Streptococcus pneumoniae using an optochin test, as viridans streptococci are optochin-resistant; they also lack either the polysaccharide-based capsule typical of S. pneumoniae or the Lancefield antigens of the pyogenic members of the genus. [5]
Pneumococcal infection is an infection caused by the bacterium Streptococcus pneumoniae. [1]S. pneumoniae is a common member of the bacterial flora colonizing the nose and throat of 5–10% of healthy adults and 20–40% of healthy children. [2]
It is sensitive to optochin when incubated in ambient air, but appears resistant or to have indeterminate susceptibility when incubated in 5% carbon dioxide. [2] Commercial DNA probe hybridization tests (e.g., AccuProbe Streptococcus pneumoniae culture identification test; Gen-Probe, San Diego, CA) are falsely positive. [2]
Streptococcus pneumoniae is the most common bacterial cause of pneumonia in all age groups except newborn infants. Streptococcus pneumoniae is a Gram-positive bacterium that often lives in the throat of people who do not have pneumonia. Other important Gram-positive causes of pneumonia are Staphylococcus aureus and Bacillus anthracis.
With the increase in drug-resistant Streptococcus pneumoniae, antibiotics such as cefpodoxime may become more popular. [21] Hospitalized children receive intravenous ampicillin, ceftriaxone or cefotaxime, and a recent study found that a three-day course of antibiotics seems sufficient for most mild-to-moderate CAP in children. [22]
Streptococcus pneumoniae and a group of oral streptococci (Streptococcus viridans or viridans streptococci) display alpha-hemolysis. Alpha-hemolysis is also termed incomplete hemolysis or partial hemolysis because the cell membranes of the red blood cells are left intact.