Common bugs from common sources Common drugs at common doses

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Common bugs from common sourcesCommon drugs at
common doses

• An evidence based look at the clinical questions
  that arise in the management of Bacteremia.
• Chris Manasseh, MD
• Monday July 7, 2003

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Common Clinical Questions in the Management of
Bacteremia

• Who is at risk for bacteremia?
• How is nosocomial bacteremia different from
  community acquired bacteremia?
• What are some of the factors that predict MRSA
  bacteremia?
• When is a positive blood culture with common skin
  flora clinically significant and not a
  contaminant?
• Who should receive Vancomycin as initial empiric
  antibiotic therapy for bacteremia?
• What is the Inpatient Standard of care for the
  treatment of bacteremia?
• What is the optimal duration of treatment for
  bacteremia?

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Who is at risk for bacteremia? with which
bacteria? Staph.aureus or coagulase negative
Staph.

• Staph.aureus Bacteremia (SAB) Highly virulent
• Site of Infection
• High risk site such as skin, bone, joint, burn,
  decubitus ulcer
• Type of patient
• IV drug abuser
• Hemodialysis patient
• Coagulase Negative Staphylococcus Less virulent
• Site of Infection
• Commonly associated with central or peripheral
  intravenous catheter
• Type of patient
• Immunocompromised patient such as AIDS,
  Malignancy, malnutrition, poorly controlled
  diabetes, cirrhosis, chronic steroid therapy
• Neutropenic patient

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Nosocomial vs. Community acquired Bacteremia

• Nosocomial/Hospital acquired Bacteremia
• Bacteremia occurs after three or more days of
  hospitalization in any health care facility
• due to central venous catheter
• Community Acquired Bacteremia
• Commonly seen in IV drug users
• Clinically inapparent source of bacteremia
• (vertebral osteomyelitis or epidural abscess)

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Factors that predict MRSA bacteremia

• Age greater than 70 years
• Past Medical History
• MRSA identified in clinical cultures, either h/o
  MRSA infection or colonization
• H/o hospitalization during the past year
• Drug History less likely to use IV drugs
• Current Hospitalization
• Prolonged hospitalization
• Nosocomial bacteremia

Strongest Predictor is prior MRSA colonization
A retrospective cohort VA study of 128 patients
with clinically significant staph.bacteremia by
the Dept.of Medicine, University of Maryland
School of Medicine, Baltimore, MD.
(Arch.Int.Med.,Vol1604/10/2000)
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Positive blood culture with common skin
floraWhen is it clinically significant and not a
contaminant?

• When one or more positive blood cultures from
  patients with intravascular catheters
• Multiple positive blood cultures or positive
  cultures from both sets of bottles in patients
  with no intravascular catheters
• One positive blood culture and a culture from
  another source shows the same organism
• Patient appears septic

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Consider Vancomycin as initial empiric antibiotic
therapy for bacteremia WHEN

• Age of patient greater than 65 years
• Prior h/o MRSA colonization
• When the bacteremia is nosocomial
• In patients with febrile neutropenia

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Inpatient Standard of care for the treatment of
Bacteremia developed by IDSA

• Statement of Purpose
• Administration of antibiotic must always be
  guided by the susceptibility report for the
  pathogen obtained from the blood cultures
• Prospective Implementation Stepwise approach
• Antibiotic susceptibility report becomes
  available to microbiology lab
• Report sent immediately to pharmacy
• Pharmacy compares test result with antibiotic
  prescribed empirically
• If the two match then physician not contacted
• If the antibiotic prescribed is not appropriate
  in light of the susceptibility report, then
  prescribing physician contacted
• Physician prescribes antibiotic effective against
  pathogen isolated and consistent with hospital
  formulary

Clinical Infectious Disease1994, volume 18
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Optimal duration of treatment for bacteremia
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Staph. aureus bacteremia
A 21 y/o IV drug abuser presents to the hospital
with a temp. of 102.4F. Blood cultures have grown
S. aureus and sensitivity results show the
organism to be resistant to Levofloxacin and
Oxacillin but sensitive to Bactrim and
Vancomycin. What is the optimal therapy? 1.
Oral Bactrim for 28 days 2. IV Bactrim for 14
days 3. IV Vancomycin until patient afebrile for
24 hours, then switch to Bactrim orally for
10-14 days. 4. IV Vancomycin for 14 days 5. IV
Vancomycin for 4-6 weeks
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Urosepsis, MSSA bacteremia and heart murmur
A 25 y/o woman with a h/o holosystolic murmur
experiences fever, chills and back pain. UA shows
many WBCs and bacteria. Urine and blood cultures
are both positive for MSSA. Which of the
following is the appropriate course of
action? 1. Oxacillin IV 2gm q4 until patient
afebrile, then dicloxacillin 250mg po q6 for 14
days. 2. Oxacillin IV 2gm q4 for 14 days 3.
Oxacillin IV 2gm q4 for 42 days 4. If TTE
positive for vegetations give Oxacillin for 42
days, otherwise give only for 14 days. 5. If
TEE positive for vegetations Oxacillin given for
42 days, otherwise given only for 14 days
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Clinical ScenariosComparing 3 patients admitted
with cellulitis