ID algorythms GP&GN organisms 5-11

ID algorythms - Gram-positive Bacteria Gram-positive Cocci Bacilli Anaerobic Anaerobic Peptococcus Peptostreptococcus Lactobacillus

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Gram-positive Bacteria Rapid identification of Gram-positive bacteria based on morphology and preliminary biochemical tests can help to direct therapy (with the caveat that the tests are 100% accurate and definitive therapy should be based final culture and susceptibility results). 1) Morphology : Most important Gram-positive pathogens are cocci (spheres) rather than bacilli (rods). The finding of Gram- positive bacilli should be interpreted within the clinical context: in blood cultures, Gram-positive bacilli often represent common skin contaminants (such as Propinibacterium , Corynebacterium , and Bacillus species). Detection of Gram-positive bacilli from necrotizing would infections suggests clostridial infection, whereas the finding of Gram-positive bacilli in CSF cultures raises the concern for Listeria . 2) Colony clustering : Within the Gram-positive bacilli, the staphylococci tend to form clusters, whereas the streptococci (including enterococci) typically appear in pairs or chains. The rapid catalase test also helps to differentiate staph from strep. Again, the clinical context aids in interpretation: the finding of streptococci in a respiratory culture would suggest
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This note was uploaded on 09/14/2011 for the course PHARM TBL taught by Professor Staff during the Spring '11 term at UCSD.

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ID algorythms - Gram-positive Bacteria Gram-positive Cocci Bacilli Anaerobic Anaerobic Peptococcus Peptostreptococcus Lactobacillus

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