Can Streptococcus pneumoniae grow on MSA?
S. pneumoniae is a fastidious bacterium, growing best at 35-37°C with ~5% CO2 (or in a candle-jar). It is usually cultured on media that contain blood, but can also grow on a chocolate agar plate (CAP). On a blood agar plate (BAP), colonies of S.
What Agar does Streptococcus grow on?
The streptococci are usually isolated on Blood agar. Blood agar is one of the most commonly used media in a clinical lab. It consists of an enriched agar base (Tryptic Soy agar) to which 5% sheep red blood cells have been added.
What test is used for identification of Streptococcus pneumoniae?
S. pneumoniae can be identified using Gram stain, catalase, and optochin tests simultaneously, with bile solubility as a confirmatory test. If these tests indicate that the isolate is S. pneumoniae, serological tests to identify the serotype can be performed.
Why does a Streptococcus species not grow on MacConkey Agar?
Streptococcus pneumoniae (S. Hence, it does not grow on MacConkey agar (MA) due to the absence of blood as well as due to the presence of high concentration of bile in the medium which is inhibitory to the growth of S. pneumoniae.
Is Streptococcus pneumoniae beta hemolytic?
Streptococcus pneumoniae, or pneumococcus, is a Gram-positive, spherical bacteria, alpha-hemolytic (under aerobic conditions) or beta-hemolytic (under anaerobic conditions), aerotolerant anaerobic member of the genus Streptococcus. They are usually found in pairs (diplococci) and do not form spores and are non motile.
Is Streptococcus pneumoniae alpha-hemolytic?
Streptococcus pneumoniae and other streptococci produce a greenish halo on blood agar plates referred to as alpha-hemolysis. This phenotype is utilized by clinical microbiology laboratories to report culture findings of alpha-hemolytic streptococci, including S.
How does Streptococcus pneumoniae grow?
Streptococcus pneumoniae is a fastidious bacterium, growing best in 5% carbon dioxide. Nearly 20% of fresh clinical isolates require fully anaerobic conditions. In all cases, growth requires a source of catalase (e.g. blood) to neutralize the large amount of hydrogen peroxide produced by the bacteria.
How does Streptococcus appear on blood agar?
As cellular division of Streptococcus spp. occurs along a single axis or plane, these bacteria grow in pairs or chains. After 18–24 h of incubation at 35–37 °C on blood agar, typically grayish-white, smooth, glossy, and translucent colonies appear with zones of α/β-hemolysis or no hemolysis.
How can Streptococcus pneumoniae be distinguished from Streptococcus Viridans on blood agar?
A green, α-hemolytic, zone surrounds S. pneumoniae colonies on blood-agar plates. Pneumococci can be differentiated from other catalase-negative viridans streptococci by their susceptibility to Optochin and solubility in bile salts.
How do lactose metabolising bacteria colonies appear on a MacConkey agar plate?
MAC contains a pH indicator that turns pink under acidic conditions. Therefore, lactose-fermenting-gram-negatives (lactose-fermenters) will form pink colonies, while non-lactose fermenters will form off-white opaque colonies.
What type of media is MacConkey agar?
MacConkey agar is an example of a medium that is both differential and selective. The presence of bile salts, as well as crystal violet, within the media prevent gram-positive organisms from growing.
How does mannitol salt agar ( MSA ) affect bacteria?
Species of staphylococci are able to tolerate this salt concentration but other pathogenic bacteria may not. This concentration inhibits the growth of most other gram-positive and gram-negative bacteria. Thus MSA selectively isolates Staphylococcus spp i.e. selective media for Staphylococcus spp.
Why does S.pneumoniae not grow on MacConkey agar?
Hence, it does not grow on MacConkey agar (MA) due to the absence of blood as well as due to the presence of high concentration of bile in the medium which is inhibitory to the growth of S. pneumoniae. However, to the best of our knowledge, we are reporting the first and unusual case of S. pneumoniae growth on MA.
How is MSA used to isolate S.aureus?
MSA has been used for many years as a selective, differential medium for the isolation of S. aureusand has long been recommended as one of the selective media for use with CF patients’ respiratory specimens (4).
How to isolate Staphylococcus and Streptococcus from the nose?
Subsequent biochemical testing will demonstrate the variability seen among the microbiota of your body. In this session, you will isolate Staphylococci bacteria from your nose and Streptococcus from your throat. 1. Working with your lab partner collect two MSA plates (plate 1 for nose samples, plate two for provided bacterial species) 2.