Bacteremia: Interpreting GenMark ePlex® Results – VASP

Background

• When BCx turn positive, the lab reports Gram stain and GenMark ePlex® results to help guide empiric therapy, while awaiting further species identification and susceptibilities.

Management

• Start empiric antibiotic therapy (based on clinical picture and table below)

• Consider ordering repeat BCx x2 based on organism to document clearance

  • Repeat for: Staph (MRSA or MSSA), Strep lugdunensis
  • If source control & no endovascular infxn, no need to repeat (most other strep and GNR’s)

• VUMC antibiograms can be used to reference typical resistance patterns and most common organisms in blood cultures.

• Candida in a blood culture is NEVER considered a contaminant

GRAM POSITIVE COCCI 

Organism	Resistance Marker	Preliminary Recommendation
Staphylococcus aureus or Staphylococcus lugdunensis ID Consult REQUIRED	mecA detected	Start vancomycin IV
	No mecA detected	Start nafcillin or cefazolin Stop empiric vancomycin IV
Staphylococcus epidermidis -Often skin contaminant -Repeat cultures, start therapy if uncertain	mecA detected	Start vancomycin IV
	No mecA detected	Start nafcillin or cefazolin Stop empiric vancomycin IV
Other coagulase negative Staph -Often skin contaminant -Repeat cultures, start abx if uncertain		Start vancomycin IV
Streptococcus: agalactiae, pyogenes, anginosus		Start penicillin IV or CTX IV Stop empiric vancomycin
Streptococcus pneumoniae		Start ceftriaxone Stop empiric vancomycin Await PCN sensitivity data
Other Streptococcus -May be contaminant		Start ceftriaxone Stop empiric vancomycin Await PCN sensitivity data
Enterococcus faecalis ID Consult REQUIRED	vanA or vanB detected	Start daptomycin 8-10mg/kg/day IV Don’t treat w vancomycin IV Contact precautions
	No vanA or vanB	Start ampicillin Stop empiric vancomycin IV
Enterococcus faecium ID Consult REQUIRED	vanA or vanB detected	Start daptomycin 8-10mg/kg/day IV Don’t treat w vancomycin IV Contact precautions
	No vanA or vanB	Start vancomycin IV Follow-up ampicillin sensitivities
Micrococcus -Often if in a single blood culture is skin contaminant		Repeat BCx Start vancomycin IV if uncertain

GRAM POSITIVE RODS

Organism	Preliminary Recommendation
Listeria monocytogenes	Start ampicillin Stop empiric vancomycin IV
Other Gram positive rod (e.g. Bacillus cereus, Corynebacterium, Cutibacterium acnes, Lactobacillus) -Often skin contaminant -Repeat cultures, start therapy if uncertain	Start vancomycin IV Follow-up sensitivities; some GPRs are resistant to vancomycin

GRAM NEGATIVE RODS *Consult ID if carbapenem resistance detected*

Organism	Preliminary Recommendation
Acinetobacter baumannii	Start ampicillin/sulbactam
Bacteroides fragilis	Start metronidazole If polymicrobial infection, piperacillin/tazobactam, ampicillin/sulbactam, or meropenem based on other organisms Do NOT double cover anaerobes
Citrobacter spp.	Start/continue cefepime
Cronobacter sakazakii	Start/continue cefepime
Enterobacter (non-cloacae complex)	Start/continue cefepime
Enterobacter cloacae complex	Start/continue cefepime
Escherichia coli	Continue empiric coverage and await susceptibilities
Fusobacterium nucleatum Fusobacterium necrophorum	Start ampicillin/sulbactam or start/continue metronidazole
Haemophilus influenzae	Start/continue ceftriaxone
Klebsiella oxytoca	Continue empiric coverage and await susceptibilities
Klebsiella pneumoniae group	Continue empiric coverage and await susceptibilities
Morganella morganii	Start/continue cefepime
Neisseria meningitidis	Continue empiric coverage and await susceptibilities
Proteus spp. Proteus mirabilis	Continue empiric coverage and await susceptibilities
Pseudomonas aeruginosa	Start/continue cefepime or piperacillin-tazobactam
Salmonella spp	Start/continue ceftriaxone
Serratia spp. Serratia marcescens	Start/continue cefepime
Stenotrophomonas maltophilia	Start trimethoprim-sulfamethoxazole (15-20mg/kg/day divided q8h for normal renal function)
Gram-Negative Resistance Genes
CTX-M Positive (ESBL)	Start meropenem Consider an Infectious Diseases consult Contact precautions (see Infection Prevention website)
IMP Positive KPC Positive NDM Positive OXA (OXA-23 and OXA-48) Positive VIM Positive	Carbapenemase-producing organism Obtain Infectious Disease consultation Contact precautions (see Infection Prevention website)

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Last update: 2022-06-21 22:17:43