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PetriKey

Identification flow

Gram-positive Cocci

Clusters, chains, catalase, coagulase

  1. Gram-positive cocci

    Start with arrangement and catalase. This is an educational study flow, not a diagnostic protocol.

    Reference Gram stain

    1. Clusters

      Clusters suggest staphylococci in many intro algorithms. Check catalase/coagulase concepts.

      Reference Staphylococcus aureus · Staphylococcus epidermidis · Catalase test

      1. Coagulase branch

        Coagulase positive points to S. aureus. Coagulase negative points to coagulase-negative staphylococci.

        Reference Staphylococcus aureus · Staphylococcus epidermidis · Coagulase test

    2. Chains or pairs

      Chains/pairs suggest streptococci/enterococci in basic study flows. Hemolysis and other tests refine the branch.

      Reference Streptococcus pyogenes · Streptococcus pneumoniae

      1. Beta-hemolytic clue

        Group A beta-hemolytic vocabulary is a classic S. pyogenes anchor.

        Reference Streptococcus pyogenes

      2. Alpha-hemolytic diplococci

        Lancet diplococci, capsule, optochin sensitivity, and bile solubility are S. pneumoniae study clues.

        Reference Streptococcus pneumoniae