Gram Positive Bacilli and Intracellular Bacteria

Study Notes

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.

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:
- 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.