STREPTOCOCCUS 411 Lab 5 Amany Niazy Streptococci All

STREPTOCOCCUS 411 , Lab 5 Amany Niazy

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

Gram Stain STAPHYLOCOCCI STREPTOCOCCI

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

Streptococcus Classification �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 (formaly known as Group D

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

STREPTOCOCCUS VIRIDANS S. PNEUMONIAE

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

VIRIDANS STREPTOCOCCI � GPS in chains S. PNEUMONIAE � GPC elongated (Lanceolated) diplococci

1. Optochin Test �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

Optochin Disk

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

Bile Solubility in Tube � � � 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

Bile Solubility on Plate 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 Detection of S. pneumoniae �Rapid latex and coagglutination tests are available to detect capsular pneumococcal antigen in CSF or other sterile body fluids.

Sensitivity Testing of S. pneumoniae

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