Gram positive bacteria
Interpretation of Key Phrases
- “Gram positive cocci in clusters” may suggest Staphylococcus 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)
- Coagulase Positive: Staph aureus
- Always consider as true bacteremia (and not a contaminant) due to the danger of delaying treatment[1]
- Coagulase Negative:
- Staph epidermidis
- Most common cause of catheter-related bacteremia[2]
- Most common skin contaminant found in blood cultures[3]
- Staph saprophyticus
- UTIs in women
- Staph lugdunensis
- Rare cause of endocarditis, meningitis, and Skin and Soft Tissue Infections
- Staphylococus lugdunensis should raise concerns for endocarditis with a single positive blood culture[4]
- Staph haemolyticus
- Rare cause of endocarditis, meningitis
- Staph epidermidis
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 | |
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
Table Overview
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See Also
References
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
- ↑ 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.
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp
- ↑ Antibiotic Therapy for Positive Blood Cultures. Perez-Jorge EV, et al. Antimicrobe. http://www.antimicrobe.org/new/e38rev2.asp