Bacteremia on management of SSTI Flashcards
What is an example of bacteremia for each
Transient
Intermittent
Persistent/sustained
Transient
- tooth brushing, biopsy
- quickly cleared
Intermittent (spurts of bacteria into blood)
- Abscess
- UTI, pneumonia, SSTI
Persistent/sustained
- Endocarditis
- infected thrombi’s
- infected mesh wiring
How do we collect blood cultures?
How many bottles?
From where do we collect?
2 sets (4 bottles total) (1 for aerobic, other for anaerobic)
Each set collected from different access point (central line, PICC, dialysis, Venipuncture/peripheral, etc..) - to reduce chance of contamination
Which are more common in collecting cultures, false negatives of positive
False positive
What are reasons for false negatives in culture (3)
Drawn after antimicrobials started
Inadequate volume of blood collected
Slow-growing pathogen (eg. anaerobes)
What are reasons for false positives in culture (2)
bad hand hygiene
Collected from colonized venous catheter
Blood culture incubation time? What takes longer?
How to assess the culture?
Incubate for 5 days
- Fastidious organisms take longer
CO2 detected with a light sensor, will only be detectable once enough bacteria is making CO2
When do most organisms show growth?
How long do you wait until the results are likely negative?
Most will show growth in 48 hours
If nothing in >72 hours - most likely negative
What does a short time to positivity indicate about bacteria
The higher the bacterial load
What bugs are gram-positive cocci clusters
Staphylococcus auerus
What bugs are gram-positive cocci pairs
streptococcus pneumoniae
What bugs are gram-positive cocci chains (2)
Streptococcus pyogenes
Streptococcus pneumoniae
What bugs are gram-negative cocci
N. Gonorrhea
What bugs are gram-negative bacilli non-lactose fermenter oxidase positive
Pseudomonas spp
What do you do if there is no clinical evidence of infection? Especially if (3)
Consider contamination
- Time to positivity TTP is 72hrs+
- only one site positive
- Growth is common skin contaminant
Which bugs are common skin contaminant (5)
Most bacillus spp
Corynebacterium
Propionibacterium acnes
Coagulase-negative staphylococci
**Staph aureus should never be ruled out
What is an endovascular infection? Give examples (2)
bacteria getting stuck to components of the vasculature like a prosthetic valve/vascular stent
causing
- endocarditis
- septic thrombophlebitis
When would you suspect an endovascular infection
Persistent bacteremia despite 72 hours of appropriate therapy
What is an extravascular infection? aka seeding. Give examples of what it can cause (4)
bacteria getting stuck to things OUTISDE the vasculature like bones, joints, brain
Can cause
- Psoas (infection in muscle)
- Osteomyelitis (infection in bones esp. if fractured, hip replacement)
- Pulmonary (infection in the lung)
- Cerebral septic emboli (infection in the brain)
When do we suspect an extravascular infection
organ-specific symptoms present OR still febrile despite 72 hours of appropriate therapy
T/F seeding (extravscular metastic infection) is more common in GAS vs staph aueus
False
- seeding is more common in staph aureus
T/F it is common to see seeding in gram neg bacteria
False
What pathogens are more likely to cause bloodstream infections or endocarditis
- Staph aureus, Candida spp
- Streptococcus
- Other gram-positives
- Other gram-negatives
Which bug is the most common cause of bacteremia but risk of endocarditis is low (not sticky) (2)
S. pneumonia
S. pyogenes
Which bug is the least common cause of bacteremia but risk of endocarditis is high (very sticky)
S. mutans
What do you do if a culture is positive for staph aureus?
Always look for seeding/metastatic infection (extravascular infection)
What to do if a patient has an endovascular or metastic infection due to SSTI
Drives therapy
- eg. prolonged duration
- additional interventions
For patients with hospitalized SSTI do we perform a blood culture or not? What do the results look like?
Yes perform blood culture
- likely negative result but could be positive
What bugs do we empirically treat for while waiting for blood culture?
Group A strep GAS
Staph aureus
- Add on MRSA if pt has active MRSA risk factors
What abx do you give while patient is hospitalized and bacteremia is suspected as you wait for blood culture?
What if MRSA is a concern?
Oral therapy if option has high bioavailability (FQs, linezolid, Septra)
MRSA concern:
IV Beta-lactam
Cefazolin or Cloxacillin
What case of hospitilization would absolutley require a blood culutre
Abscess
- due to risk of S. aureus bacteremia
What if the culture results at 48-72 hours is negative:
Positive:
Negative: transition to ORAL beta-lactam (duration: 5 to 7 to 10 days)
Positive: may need to continue IV
Which bug do we not need to confirm clearance with repeat blood culture in bacteremia
Group A strep
Streptococcal bacteremia
What does the balance trial say for duration of therapy for SSTI with GAS bacteremia?
Bottom line?
Extend SSTI treatment to 7 days, no need for 14 days
Bottom line:
- Treat cellulitis for 5 days. If streptococcal bacteremia due to cellulitis. Use a 7 day duration
What is the treatment and duration for SSTI with staph. Aureus MSSA bacteremia.
Cloxacillin or cefazolin for
14 days min.
If life threatening beta-lactam allergy
- vancomycin (however inferior for MSSA)
- Clindamycin or Septra
What does the ARENSMAN trial say about IV to oral transition in SSTI with GAS bactemeria?
- Give at least 3 days (72 hours) of IV beta-lactam (as long as some improvement by day 3) before transitioning to oral
- Transition to HIGH (maximized) dose oral beta-lactam when you do switch
Stepping down before day 3 is more likely to fail
What is the overall steps for management of SSTI with S. aureus bacteremia (3)
- Consult ID
- Always look for endovascular or metastic infection
- remove IV lines - Repeat culture q48 hours until negative
What is ID consult associated with? (2)
Decreased mortality and decreased relapse
What is the most to least common sites of Staph aureus metastatic infection?
Heart valve (infective endocarditis)
Joints (septic arthritis)
Lungs (septic PE)
Bone (vertebral osteomyelitis)
Muscle
Spine (Epidural abscess)
What does the SABATO trial tell us about IV- oral switch in SSTI with staph. aureus MSSA bacteremia?
Most commom PO drug used in this trial?
Can transition from IV to HIGH oral dose after 5-7 days of IV therapy (14 days total)
- Cloxacillin or cefazolin are viable IV options
Trial used Sulfatrim as PO abx
What is defined as uncomplicated MSSA Bacteremia (4)
- no evidence of metastatic infection
- no indwelling devices or prosthetic valves
- clearance of MSSA on culture in ≤48 hours
- no fever within 72 hours of ABX therapy
