Gram positive bacteria

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Interpretation of Key Phrases

  • “Gram positive cocci in clusters” may suggest Staphyloccocus species.
  • "Gram positive cocci in pairs and chains" may suggest Streptococcus species or Enterococcus species
  • “Branching Gram positive rods, modified acid fast stain positive” may suggest Nocardia or Streptomyces species

Cocci

Clusters (Staph Species)

Chains or Pairs (Strep Species and Related)

  • Enterococcus (e.g. Enterococcus faecalis, Enterococcus faecium)
    • May cause bacteremia in the proper clinical setting (UTI, intra-abdominal infections, infected vascular catheters, and endocarditis)[5]
  • Strep viridans
    • In general are low virulence pathogens and likely contaminants (21-50% of positive blood cultures are clinically significant)
    • Risk factors for VGS bacteremia include: neutropenia, oral mucositis, irradiation to the oral cavity, antibiotic prophylaxis with trimethoprim-sulfamethoxazole and fluoroquinolones, intravenous hyperalimentation, high dose chemotherapy
  • Streptococcus pneumoniae (Pairs)
    • Asociated with pneumonia, meningitis, peritonitis and other severe infections
    • Isolation of this organism is always significant and should be treated[6]
  • Other Strep Species
    • ß-hemolytic streptococcus (Group A Streptococcus, Group B Streptococcus, etc)

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

Antibiogram

Category Organism Strep. Group A, B, C, G Strep. Pneumoniae Viridans strep Strep. anginosus gp Enterococcus faecalis Enterococcus faecium MSSA MRSA CA-MRSA Staph. Epidermidis C. jeikeium L. monocytogenes
Penicillins Penicillin G S S I S S I R R R R R S
Penicillin V S S I S S I R R R R R R
Anti-Staphylocccal Penicillins Methicillin S S I S R R S R R S R R
Nafcillin/Oxacillin S S I S R R S R R S R R
Cloxacillin/Diclox. S S I S R R S R R S R R
Amino-Penicillins AMP/Amox S S I S S I R R R R R S
Amox-Clav S S I S S S S R R R R X2
AMP-Sulb S S I S S S S R R R R S
Anti-Pseudomonal Penicillins Ticarcillin S S I S I I R R R I R S
Ticar-Clav S S I S I I S R R I R X2
Pip-Tazo S S I S S I S R R S X1 X2
Piperacillin S S I S S I R R R R R S
Carbapenems Doripenem S S S S I R S R R S X1 S
Ertapenem S S S S R R S R R S R I
Imipenem S S S S S I S R R S R S
Meropenem S S S S I R S R R S X1 S
Aztreonam R R R R R R R R R R R R
Fluroquinolones Ciprofloxacin I I R R U R S R I S R S
Ofloxacin I I R R U R S R X1 S R R
Pefloxacin R R X1 X1 R R S R X1 S X1 R
Levofloxacin S S S S S R S R I S X1 S
Moxifloxacin S S S S S I S I I S X1 S
Gemifloxacin S S S S S I S I I S X1 S
Gatifloxacin S S S S S I S I I S X1 S
1st G Cephalo Cefazolin S S S X1 R X1 S R R I R R
2nd G. Cephalo Cefotetan S S S X1 R X1 S R R I R R
Cefoxitin S S S X1 R X1 S R R I R R
Cefuroxime S S S X1 R X1 S R R I R R
3rd/4th G. Cephalo Cefotaxime S S S X1 R X1 S R R I R R
Cefizoxime S S S X1 R X1 S R R I R R
CefTRIAXone S S S X1 R X1 S R R I R R
Ceftaroline S S S X1 S X1 S S S S X1 X1
CefTAZidime S S I X1 R X1 I R R I R R
Cefepime S S S X1 R X1 S R R I X1 R
Oral 1st G. Cephalo Cefadroxil S S S X1 R X1 S R R I R R
Cephalexin S S S X1 R X1 S R R I R R
Oral 2nd G. Cephalo Cefaclor/Loracarbef S S S X1 R X1 S R R I R R
Cefproxil S S R X1 R X1 S R R I R R
Cefuroxime axetil S S S X1 R X1 S R R I R R
Oral 3rd G. Cephalo Cefixime S S S X1 R X1 R R R R R R
Ceftibuten S I R X1 R X1 R R R R R R
Cefpodox/Cefdinir/Cefditoren S S S X1 R X1 S R R I X1 R
Aminoglycosides Gentamicin R R X1 X1 S S S R X1 I R S
Tobramycin R R X1 X1 S R S R X1 I R S
Amikacin R R X1 X1 S R S R X1 I R S
Chloramphenicol S S X1 X1 I I I R X1 R R S
Clindamycin S S X1 X1 R R S R I R R X1
Macrolides Erythromycin I I X1 X1 R R I R I I R S
Azithromycin I I X1 X1 R R S R I R R S
Clarithromycin I I X1 X1 R R S R I R R S
Ketolide Telithromycin S S X1 X1 I R S R I R R S
Tetracyclines Doxycycline I S X1 X1 R R I I S R R S
Minocycline S S X1 X1 R R S I S R R S
Glycylcycline Tigecycline S S X1 X1 S S S S S S S S
Daptomycin S X23 X1 X1 S S S S S S S I
Glyco/Lipoclycopeptides Vancomycin S S X1 X1 S I S S S S S S
Teicoplanin S S X1 X1 S I S S S I S S
Telavancin S S X1 X1 S S S S S S S S
Fusidic Acid I I X1 X1 S X1 S S S S S X1
Trimethoprim S I X1 X1 S R I I S S R S
TMP-SMX X22 S X1 X1 X22 R S S S I R S
Urinary Agents Nitrofurantoin S S X1 X1 S S S S S X1 R X1
Fosfomycin X1 S X1 X1 S I S S S X1 X1 R
Other Rifampin S S X1 X1 I R S S S S S S
Metronidazole R R X1 X1 R R R R R R R R
Quinupristin dalfoppristin S S X1 X1 R S S S S S S S
Linezolid S S X1 X1 S S S S S S S S
Colistimethate R R X1 X1 R R R R R R R R

Clinical Identification Chart

Gram-Positive Classification.png

Table Overview

See Also

References

  1. Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
  2. Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
  3. Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
  4. Liu Po-Yen et al. Staphylococcus lugdunensis Infective Endocarditis: A Literature Review and Analysis of Risk Factors. Journal of Microbiology, Immunology and Infection Volume 43, Issue 6, December 2010, Pages 478-484.
  5. Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
  6. Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp