Staphylococci

• Catalase Test


  Test the ability of the organism to breakdown of H2O2(3%) into oxygen and water
• Characteristics of Gram Positive Cocci

  • Gram positive, Catalase Positive
  • The Family Micrococcaceae
  • Three Genera's: Planococcus, Stomatococcus, Micrococcus
  • The Family Staphylococcaceae
  • Gram positive, Catalase Positive
  • Genera: Staphylococcus
  • Gram positive, Catalase Negative
  • The Family Streptococcaceae
  • Gram positive, Catalase Negative
  • Genera: Streptococcus
• Clinically Significant Species of Staphylococci

  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Staphylococcus saprophyticus
  • Staphylococcus lugdunensis
  • Staphylococcus haemolyticus
• Microdase Test (Modified Oxidase Test)


  Test for the position of Cytochrome to produce a dark-blue end product when reacted with Microdase Reagent
• Characteristics of Gram-Positive Cocci

  • Contain a high content of peptidoglycan and low level of lipid in the cell wall
  • Gram-positive infections are pyogenic
• Staphylococci

  • General Characteristics: Gram (+) cocci arranged in tetrads or clusters, Facultative anaerobes, Catalase positive, Oxidase Negative, Non-motile, non-spore-forming glucose fermenters, Grows in 7.5-10% NaCl, Small-colony variants- rare strain, fastidious, req. CO2, hemin for growth
• Clinically Significant Species of Staphylococci

  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Staphylococcus saprophyticus
  • Staphylococcus lugdunensis
  • Staphylococcus haemolyticus
• Protein A of Staphylococcus aureus

  1. Binds to the Fc portion of IgG, neutralizes it and blocks phagocytosis

  2. Beta lactamase (Penicillinase) - Breakdown of beta-lactam ring in penicillin molecule
• Toxic Shock Syndrome Toxin (TSST-1) of Staphylococcus aureus

  1. Formerly known as Enterotoxin F (superantigen-activates aggressive immune response)

  2. Causes menstruating-associated TSS (Tampon use) absorbed through vaginal mucosa
• Virulence Factors of Staphylococcus aureus

  1. Enterotoxins

  2. Toxic Shock Syndrome Toxin-1

  3. Exfoliative Toxin

  4. Cytolytic toxins

  5. Enzyme

  6. Protein A
• Cytolytic Toxins of Staphylococcus aureus

  1. Panton-Valentine Leukocidin (γ-Hemolysin) - Destruction of neutrophils and macrophages

  2. Hemolysins (α, β, δ) - Lyse erythrocytes
• Epidermolytic toxins A and B of Staphylococcus aureus


  1. Also known as Exfoliatin serotypes A and B

  2. Causes SSS (Scalded Skin Syndrome or Ritter disease) and bullous impetigo (large pustules with erythema)
• • Folliculitis- mild inflammation of hair follicle or sebaceous gland
  • Furuncles (boils)- large, raised
• Enzymes of Staphylococcus aureus

  Coagulase (Staphylocoagulase), Fibrinolysin (Staphylokinase), Deoxyribonuclease (DNAse), Hyaluronidase, Lipase
• Enterotoxins of Staphylococcus aureus

  1. Heat stable exotoxins: A-E and G-J

  2. A, B and D are associated with food poisoning (diarrhea, vomiting); reheating contaminated food will not prevent disease

  3. Enterotoxin B (superantigen) linked to pseudomembranous enterocolitis
• Staphylococcus aureus


  • Most clinically significant specie of Staphylococci
  • Present in various skin surfaces and nares
  • Causes infection when it enters a normally sterile site
  • Cause of nosocomial or hospital-acquired infections
  • Common cause of food poisoning
  • Can be cultivated by adding 7.5% to 10% NaCl
• Staphylococcus lugdunensis

  • Gene mecA - encodes for oxacillin resistance
  • Community associated and hospital-acquired infections (endocarditis and UTI)
• Infections or Associated Disease caused by Staphylococcus aureus

  • Scalded Skin Syndrome (Ritter disease)- extensive exfoliative (profuse peeling) dermatitis caused by staphylococcal exfoliative or epidermolytic toxin
  • Toxic Shock Syndrome - fatal disease characterized by sudden onset of fever, chills, vomiting, diarrhea, muscle aches, and rash, which could lead to hypotension and shock
  • Toxic Epidermal Necrolysis (TEN)- clinical manifestation with multiple causes; it is most commonly drug-induced, but some cases may have been linked to infections and vaccines
• Staphylococcus epidermidis


  • Exopolysaccharide “slime” or biofilm
  • Enhances organisms adhesion to implanted medical devices and provides refractoriness to host defense
• General Characteristics of Staphylococci

  • Clinically Significant Species
  • Laboratory Diagnosis
• Infections or Associated Disease caused by Staphylococcus aureus

  • Skin and Wound Infections
  • Folliculitis- mild inflammation of hair follicle or sebaceous gland
  • Furuncles (boils)- large, raised, superficial abscess
  • Carbuncles- invasive lesions develop from multiple furuncles, may progress into deeper tissues
  • Bullous Impetigo- pustules are larger and surrounded by a small zone of erythema
• Clinically Significant Species of Staphylococci

  • Staphylococcus aureus
  • Staphylococcus epidermidis
  • Staphylococcus saprophyticus
  • Staphylococcus lugdunensis
  • Staphylococcus haemolyticus
• Staphylococcus haemolyticus


  • Vancomycin resistance
  • Community associated and hospital-acquired infections (endocarditis and UTI)
• Staphylococcus saprophyticus

  • Adheres to the epithelial cells lining the urogenital tract
• Laboratory Diagnosis of Staphylococci

  • Isolation and Identification
  • Cultural Characteristics
  • Identification Methods
  • Isolation and Identification
• Culture Media for Isolation and Identification

  • Blood Agar
  • Colistin-nalidixic acid or Phenylethyl Alcohol agar
  • Mannitol Salt Agar
• General Characteristics

  • Staphylococci
• Bacitracin Susceptibility Test: Susceptible for Micrococcus if zone diameter greater than 10 mm, Resistant for Staphylococcus
• Growth on Colistin-Nalidixic Agar (CNA)/ Phenylethyl Alcohol Agar (PEA)

  • Staphylococcus and Streptococcus grow
  • E. coli is totally inhibited
  • P. mirabilis shows partial inhibition
• Catalase Test: Positive for Staphylococcus and Micrococcus, Negative for Streptococcus
• Laboratory Diagnosis

  1. Isolation and Identification

  2. Cultural Characteristics

  3. Identification Methods
• Colistin-Nalidixic Agar (CNA)/ Phenylethyl Alcohol Agar (PEA)

  1. Selective for gram-positive bacteria

  2. Colistin and nalidixic acid/ Phenylethyl alcohol inhibit Gram (-) Bacteria
• Clinically Significant Species

  • Staphylococci
• Staphylococcus species


  • Staphylococcus lugdunensis
  • Staphylococcus haemolyticus
  • Staphylococci
• Isolation and Identification

  1. Specimen: Aspirate or Swabs

  2. Culture Media
• Microdase Test: Positive for Micrococcus spp., Negative for Staphylococcus spp.
• Coagulase Test: Differentiates Staphylococcus aureus from coagulase negative staphylococci
• Identification Methods

  1. Catalase

  2. Microdase

  3. Aerobic Growth

  4. Anaerobic Growth

  5. Bacitracin

  6. Furazolidone

  7. Lysostaphin

  8. Coagulase

  9. DNAse

  10. MSA Fermentation

  11. Novobiocin
• Coagulase Tube Test - Negative

  • No clot (S. epidermidis and others)
• Coagulase Tube Test - Negative

  • No clearing observed (S. epidermidis and S. saprophyticus)