PATHOGENS

• Sepsis (Greek, putrefaction): life-threatening organ dysfunction caused by host response to infection.[22]
  • Septic shock: a subset of sepsis in which underlying circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality than sepsis alone.[4]
  • Risk of sepsis is associated with both virulence of pathogen and immunologic vulnerabilities of host.
• Pathogens are associated with site of antecedent infection: not comprehensive list
  
  • Gram-negative bacteria: E. coli, Klebsiella, Enterobacter, Pseudomonas, Serratia
  • Gram-positive bacteria: Staphylococcus aureus, S. pneumoniae, Streptococcus species
  • Toxin mediated: Staphylococcal or streptococcal toxic shock, Clostridium difficile, Clostridium sordellii.[18]
  • Viral: influenza A, human metapneumovirus, coronavirus, and respiratory syncytial virus[7]
  • Fungal: candida
  • Rickettsial: R. rickettsii, R. typhi[14]
• Consider both (1) hosts with recognized vulnerabilities and (2) exposures to pathogens of recognized virulence.
  • Maternal and neonatal: Group B streptococci, E. coli., Group A streptococci (puerperal sepsis)[12]
  • Injection drug users: S. aureus, esp. MRSA, and Candida[8]
  • Splenectomized or functionally asplenic pts: Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Capnocytophaga canimorsus[9],Babesia spp.
  • Neutropenic: GNB, Aspergillus.
  • Traveler: malaria, salmonellosis.
  • Healthy young adult: toxic shock syndromes (S. aureus or group A strep), N. meningitidis, bioterrorism (anthrax, plague), Hantavirus, severe influenza +/- bacterial superinfection.