Gram positive bacteria

Cocci

1. Clusters (Staph Species)
   1. Coagulase Positive: Staph aureus
      1. Always consider a blood culture positive for Staphylococcus aureus to be true bacteremia (and not a contaminant) due to the danger of delaying treatment
   2. Coagulase Negative:
      1. Staph epidermidis
         1. Most common cause of catheter-related bacteremia
         2. Most common skin contaminant found in blood cultures
      2. Staph saprophyticus: UTIs in women
      3. Staph lugdunensis: endocarditis, meningitis, and Skin and Soft Tissue Infections
      4. Staph haemolyticus: endocarditis, meningitis
2. Pairs/chains (Strep Species)
   1. catalase -

Rods (Bacilli)

Organism		Cult	Morphology
Listeria monocytogenes	Small	Aero	tumbling
Diphtheroids	Small	Anaero	pallisades
Actinomyces	Small	Anaero	Branching
Propionibac	Small	Anaero	clumps/pleo
Lactobacillus	Variable	Both	may chain
Clostridium	Large	Anaero	Spores
Bacillus	Large	Aero	Spores

Clinical Identification Chart

See Also

• Microbiology (Main)