Streptococcus pneumoniae

Overview

• Commonly causes:
  • Pneumonia
  • Second most common cause of bacterial meningitis (most severe being Neisseria meningitidis)
• Characteristics:
  • Gram-positive bacteria
  • Arranged in pairs (diplococci) or short chains
  • 90 serotypes
  • Vaccines cover 20-60 serotypes

Virulence Factors

• Capsule:
  • Reduces the immune system's ability to combat infection
  • Most significant factor affecting morbidity and mortality

Natural Habitat and Carriage

• Grows on mucosal surfaces
• Often part of the natural microflora
• Carrier state does not always result in disease

Diseases Caused

• Primary causes of:
  • Community-acquired pneumonia
  • Otitis media (ear infection)
  • Bacterial meningitis (most prevalent in Israel)

Symptoms

• Early symptoms:
  • Chills
  • High fever
  • Cough with pink or rusty sputum
• If untreated:
  • Sustained fever
  • Chest pain
  • Lung pain
  • Sinusitis
  • Endocarditis
  • Arthritis
  • Bacteremia or septicemia

Demographics

• Highest incidence:
  • Under 2 years old
  • Over 60 years old
• Hosts include:
  • Humans, mice, rats, guinea pigs, chimpanzees, rhesus monkeys, and other mammals
• Opportunistic pathogen:
  • Many people carry it without developing an infection

Transmission

• Method:
  • Microaerosol droplets (coughing, sneezing)
  • Person-to-person oral contact
• Infection:
  • Infrequent in healthy individuals
• Incubation Period:
  • Speculated 1-3 days in compromised patients
• Reservoir:
  • Humans

Treatment

• Antibiotics:
  • Penicillin
  • Tetracycline
  • Ceftriaxone
  • Levofloxacin
  • Erythromycin
  • Fluoroquinolones
  • Fully susceptible to: Vancomycin (also used for TB)
• Concern:
  • Multi-drug resistant strains are emerging

Transmission and Resistance

• No zoonosis or vector transmission
• Susceptible to a variety of antibiotics, but resistance is a growing issue