STREPTOCOCCI BASMAH ALMAARIK Lecture 5 b All are

STREPTOCOCCI BASMAH ALMAARIK Lecture # 5 b

� All are Gram Positive Cocci arranged in chains (short or long) + ve - ve � All are Catalase -ve

Staphylococci streptococci

� Fastidious � Grows organism no growth on NA well on BAP � Facultative � Grow anaerobe at 37 C need 24 to 48 hour.

� Alpha hemolytic �S. viridans �S. pneumoniae � Beta hemolytic: �Group A, B, C, G & D Lancefield grouping according to antigens in their cell wall � Non-hemolytic: �Enterococcus (formally known as Group D)

� Give � It alpha hemolysis on BAP. Can be divided in to 2: � Viridans group � S. pneumoniae

Streptococcus viridans s. pneumoniae

S. PNEUMONIAE Viridans Streptococci � Alpha haemolysis � Pin point colonies � Ring form colonies � Tanslucent or mucoid Flattened with raised edges Not Capsulated � � � Optochin resistant � Optochin sensitive � Sile solubility +ve � Not part of NF Bile Solubility -ve Part of normal flora of upper respiratory and GI

Viridans Streptococci � GPS in chains S. PNEUMONIAE � GPC elongated (Lanceolated) diplococci

� Ethylhydrocupreine hydrochloride. � Zone of inhibition of 14 mm or more sensitive S. pneumoniae � No zone of inhibition S. viridans Always don on a BAP. On the primary culture of isolation plate before incubation

� To test if colonies are lysed by bile salt (such as desoxycholate) or not. � There �In are 2 ways to do the test : a tube �On plate

2 ml of saline in a tube � Emulsify several colonies of test organism in it � Divide organism suspension in 2 tubes � Add 2 drops of bile salt to one tube and 2 drops of sterile distilled water to the other. � Leave 10 -25 mn at RT �

� Add drop of bile salt to specified part of plate � Incubate at 37 C for 10 30 min � Colony disappear +ve � Colony stay -ve

� Rapid latex and coagglutination tests are available to detect capsular pneumococcal antigen in CSF or other sterile body fluids.

Thank You

� Do gram stain for S. viridance and S. pnemoniae (show it to the instructor) � Streak blood agar with S. viridance and S. pnemoniae and inoculate both organisms with Optochin disk.