PATHOGENS

• Sepsis (Greek, putrefaction): life-threatening organ dysfunction caused by the host’s response to infection.[23]
  • Septic shock is a subset of sepsis in which underlying circulatory, cellular, and metabolic abnormalities are associated with a greater mortality risk than sepsis alone.[1]
  • Both virulence of the pathogen and the host’s immunologic vulnerabilities determine the sepsis’s likelihood and outcome.
• Pathogens are associated with a 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.[20]
  • Viral: influenza A, human metapneumovirus, coronavirus,[10] and respiratory syncytial virus[13]
  • Fungal: Candida
  • Rickettsial: R. rickettsii, R. typhi[17]
• Consider hosts with recognized vulnerabilities as well as exposures to pathogens of recognized virulence.
  • Maternal and neonatal: Group B streptococci, E. coli., Group A streptococci (puerperal sepsis)[7]
  • Injection drug users: S. aureus, esp. MRSA, and Candida[11]
  • Splenectomized or functionally asplenic pts: Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Capnocytophaga canimorsus[12], 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.