Bacteremia

define bactermia

bacteria in the blood - may clear or progress to septicemia

define sepsis

the body’s response to infection including inflammation, hemodynamic instability, and end organ dysfunction

define SIRS

clinical syndrome defined with objective clinical findings of tachycardia, tachypnea, fever/hypothermia, leukocytosis/leukopenia

etiologies of bactermia

dental operations, surgery/procedure, tissue infection, foreign devices (catheters, shunts, tubing, valve replacements), trauma/burns, spontaneous

risk factors for bacteremia

dental operations, surgery/procedure, foreign devices, trauma/burns, elderly, hospitalization, immunocompromised

complications of bacteremia

meningitis, endocarditis, osteomyelitis, sepsis, cellulitis, peritonitis, brain abscesses, pneumonia, death

gram-positive pathogens

MSSA, MRSA, streptococcal species, enterococcus, anaerobes

gram-negative pathogens

E. coli, enterobacter, pseudomonas aeruginosa, klebsiella pneumoniae, anaerobes

management of bacteremia

cultures (blood, sputum, abscess, wound, indwelling catheter, port, drain), imaging (CT scan, chest Xray, ECHO, TEE, etc.), source control (catheter, drain, port removal, early and appropriate antibiotics), interdisciplinary team

broad treatment for bacteremia

IV antibiotics: vancomycin, linezolid, pip/taz, carbapenems, extended-spectrum cephalosporins

narrower treatments for bacteremia

IV antibiotics: earlier generation cephalosporins, ampicillin/sulbactam, metronidazole, anti-staph penicillin’s (nafcillin, oxacillin)

what is duration of therapy determined by?

pathogen and/or patient-specific factors

duration of therapy for patients afibrile, hemodynamically stable, source control achieved

7 days

duration of therapy for antimicrobial resistant pathogens, pseudomonas

10-14 days

duration of therapy for uncomplicated S. aureus

14 days

duration of therapy for complicated S. aureus

28-42 days

duration of therapy for osteomyelitis or endocarditis

> 42 days

when does duration of therapy begin?

always from the 1st day of negative blood cultures or source control (first day of clear blood culture)

MRSA risk factors include

IVDU, recent hospitalization (in last 12 months), hemodialysis, previous MRSA infection, immunocompromised, homeless

antibiotic options for MSSA bacteremia

nafcillin, oxacillin, dicloxacillin, 1st and 2nd gen cephalosporin

antibiotic options for MRSA bacteremia

vancomycin, linezolid, ceftaroline

antibiotic options for streptococcal bacteremia

cephalosporins, penicillin’s

what is TTE

transthoracic echocardiogram, non-invasive, ultrasound waves help visualize the heart and detect vegetation

what is TEE

transesophageal echocardiogram, requires invasive access via esophagus, local anesthetic, and better visualization.

what does vancomycin cover

gram positives (MRSA, MSSA), streptococcus, non-VRE enterococci, c. difficile (oral formulation only)

warning for vancomycin

nephrotoxic and ototoxic, oral is not for systemic indications, can cause vancomycin infusion reaction drug fever (do not exceed 1 g over one hour)

ADRs of vancomycin

SJS/TENS, drug fever, AKI, abdominal pain, ototoxicity

how does vancomycin work

binds D-Ala-D-Ala and prevents transglycosylation and transpeptidation in bacterial cell walls (glycopeptide)

general principles for vancomycin TDM

trough drawn 30 minutes before 4th or 5th dose, target AUC of 400-600, accumulation begins to occur around and after the 4th or 5th dose, and monitor renal function

target trough of vancomycin for UTI or SSTI

10-15 mcg/mL

target trough of vancomycin for MRSA and severe infections

15-20 mcg/mL

when is the higher end of vancomycin targeted?

CNS infections

treatment for suspected gram-negative bacteremia

ceftriaxone, pip/taz, cefepime, meropenem, imipenem

treatment for pseudomonas aeroginosa bacteremia

pip/taz, cefepime, ceftazidime, meropenem

treatment for non-pseudomonal bacteremias

ceftriaxone, ceftazidime, cefepime

pseudomonas risk factors: immunocompromised, healthcare exposure in prior 3-6 months, P. aeruginosa infection in prior 3-6 months, institutional prevalence of resistant gram-negative bacilli + > 20%

immunocompromised, healthcare exposure in prior 3-6 months, P. aeruginosa infection in prior 3-6 months, institutional prevalence of resistant gram-negative bacilli + > 20%

how does Zosyn work

inhibits bacterial wall synthesis by binding to penicillin-binding proteins to inhibit peptidoglycan synthesis

what does Zosyn cover

pseudomonas, MSSA, HNPEK, CAPES, enterococcus, gram positive anaerobes

T/F: Zosyn requires renal dose adjustments

true

how is Zosyn given

IV

which portion of Zosyn adds pseudomonas and CAPES coverage

tazobactam

infusion time of Zosyn

4-hour infusion time used to increase time above MIC

what does CAPES stand for?

citrobacter, acinetobacter, providencia, enterobacter, serratia

what does HNPEK

H. influenza, neisseria, proteus, E. coli, klebsiella

indications for blood cultures

new fever and no previous BC within 48 hours, occult bacteremia, sepsis, suspected meningitis, pyelonephritis, severe pneumonia, severe SSTI, endocarditis

T/F: the utility of catheter cultures is controversial, but the catheter tip may be submitted for semiquantitative culture if there is clinical suspicion of CLABSI

true

how do quality specimen collections work

avoid contamination, adequate volume, and collected prior to antimicrobial therapy

how does gram staining work

allows differentiation between gram positive and gram negative, results reported as rare, few, moderate, or many bacteria (or grading of 1+ rare to 4+ many)

how long does it take for species confirmation

24-48 hours but other species may take longer