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
         1. UTIs in women
      3. Staph lugdunensis
         1. Rare cause of endocarditis, meningitis, and Skin and Soft Tissue Infections
      4. Staph haemolyticus
         1. Rare cause of 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)