Expected Pathogens From Common Body Sites/Specimens

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Expected Pathogens From Common Body Sites/Specimens

Body Site/SpecimenOrganism(s) Commonly ExpectedComments
Blood
  • Staphylococcus species: Gram-positive cocci (GPC) in clusters and tetrads
  • Streptococcus or Enterococcus species: GPC in pairs and long chains; S. pneumoniae as GPC in lancet-shaped pairs
  • Haemophilus species: Pale pink, gram-negative coccobacilli (GNCB)
  • Pseudomonas, enteric organisms (eg E.coli), and Bacteroides species: Gram-negative rods (GNRs)
  • Clostridium or Listeria species: Gram-positive rods (GPRs)
  • Generally, only 1 morphotype is expected in sterile body sites.
  • GPC are the most commonly isolated organisms in blood, including coagulase (COAG)-negative staph, S. aureus, Enterococcus species, viridans streptococci, S. pneumoniae, and beta-hemolytic streptococci.
  • Other commonly isolated pathogens include E. coli, Candida albicans, P. aeruginosa, Klebsiella pneumoniae, Enterobacter cloacae, Proteus species, and anaerobic bacteria.
Cerebrospinal fluid (CSF)
  • Neisseria species: Gram-negative diplococci (GNDC)
  • Haemophilus species: Pale pink GNCB
  • Streptococcus species: GPC in pairs (diplococci) and long chains
  • Staphylococcus species: GPC in clusters and tetrads
  • Listeria: Gram-positive rods (GPR)
  • Generally, only 1 morphotype is expected in sterile body sites.