Gram Positive Bacilli and Intracellular Bacteria

Gram Positive Bacilli

• Listeria monocytogenes:
  • Self-limiting gastrointestinal illness
  • Neonatal listeriosis can be fatal (30% mortality rate)
  • Exposure during birth can lead to late-onset meningitis.
• Corynebacterium diphtheriae:
  • Respiratory infection
  • Symptoms include sore throat and bull neck sign.
• Nocardia spp.:
  • Pulmonary infections; can be acute or chronic (recurrent).
• Clostridioides difficile:
  • Ribotype 27 is prevalent and increasing in North America
  • Increased virulence.
  • Intrinsically resistant to fluoroquinolones.
• Cutibacterium spp.:
  • Associated with acne in teens and shoulder revisions.

Intracellular Bacteria

• Legionella pneumophilia:
  • Not a normal part of the body's flora
  • Associated with contaminated water in hospital outbreaks.
  • Chlamydia trachomatis is a major sexually transmitted infection (STI) in Canada.
• Staphylococcus aureus:
  • Commonly found in the skin and nasal cavity (40%)
  • Mannitol salt agar is used to distinguish S. aureus from other staphylococcus species.
  • MRSA requires treatment with specific drugs like Ceftaroline or Ceftobiprole (PBP-2a binding).
• Staphylococcus lugdunensis:
  • Associated with endocarditis (inflammation of the heart lining and valves), often affecting native heart valves.
• Other Coagulase-negative staphylococci (CoNS):
  • Contamination is likely if less than 14 positive blood cultures exist.
• S. saprophyticus:
  • Associated with community-acquired UTIs, common in young women.
  • A urease-positive result aids in diagnosis.

Streptococci - Group A and Group B

• Streptococci Group A:
  • Scarlet fever is a symptom that includes a strawberry tongue and red rash.
• Streptococci Group B:
  • Neonatal onset (<7 days old) sepsis and pneumonia can result.
• Streptococcus pneumoniae:
  • Leading cause of community-acquired pneumonia
  • Symptoms include lobar pneumonia, fever and shortness of breath.
  • Diagnostic test: Bile solubility test
• Streptococcus anginosus:
  • Associated with deep tissue abscesses. These bacteria are anaerobic.
• Enterococcus spp.:
  • Very intrinsically resistant to many antibiotics, including Ampicillin (especially E. faecalis). E. faecium is less sensitive.