Lecture Notes: Identification of Organisms in the Lab

Introduction to Variance Factors

• Variance Factors: Utilized to identify organisms in the lab.
• Focus on virulence vectors to identify:
  • Staphylococcus (Staph) species
  • Streptococcus (Strep) species

Common Organisms and Associated Infections

Staphylococcus Epidermidis (Staph Epi)

• Infections: Upper respiratory tract infections.
• Diagnosis: Often involved in skin and respiratory infections.

Streptococcus Infections

• Upper Respiratory Tract:
  • Strep Throat: Caused by Streptococcus, symptoms include chills, fever, headache, sore throat.
  • Diagnosis: Through throat culture.
  • Personal Experience: Strep throat often accompanied by stomach aches.
• Sinusitis:
  • Caused by organisms like Staph aureus, Strep pneumonia, Strep pyogenes.
  • Symptoms: Lack of drainage, compacted environment for bacteria.
  • Treatment: Often requires antibiotics.
  • Personal Note: Recurrent sinus infections in children.
• Bronchitis and Pneumonia:
  • Caused by Strep pneumonia and Staph.
  • Progression: Infections spreading to the lungs are termed pneumonia.

Skin Diseases

Pyoderma

• Caused by Staph, Strep, or Corynebacteria.
• Conditions: Highly contagious, commonly observed in children.
• Examples: Pimples, styes, and external abscesses (furuncles, boils).
• Special Note: Misdiagnosis of chickenpox as a furuncle.

Serious Skin Conditions

• Carbuncle: Massive skin lesions.
• Scaled Skin Syndrome: Caused by exotoxins from Staph aureus.
  • Common in infants, can lead to high fever and require treatment.

Other Notable Staph and Strep Diseases

Strep agalactiae (Group B Strep)

• Concern: For pregnant women, potential complications for newborns like meningitis and pneumonia.
• Screening: Pregnant women tested around 37 weeks.

Strep pyogenes

• Causes: Strep throat, scarlet fever.
  • Scarlet fever caused by a strain with a temperate phage.
• Treatment: Antibiotics are effective.
• Personal Anecdote: Misunderstanding of scarlet fever due to popular media.

Strep pneumonia

• Conditions: Pneumonia and meningitis.
  • Meningitis can be life-threatening, caused by bacterial infection.

Staph aureus

• Common Presence: Exists on the human body.
• Specific Strain: MRSA (Methicillin-resistant Staphylococcus aureus) is of particular concern.
• Personal Experience: Cellulitis incidents in the household.

Toxic Shock Syndrome

• Cause: Certain strains of Staph aureus.
• Awareness: Frequently mentioned in tampon usage warnings.
• Possibility: Can occur in males.

Laboratory Work

• Objective: Work with Staph and Strep organisms to identify and study these common pathogens.