Bacteremia and Sepsis Flashcards
- presence of viable bacteria in the blood
- one of the most serious infections
Bacteremia
contamination of blood through phlebotomy
Pseudobacteremia
bacteremia present with the absence of physical signs/symptoms
Occult Bacteremia
prolonged Bacteremia plus clinical presentation of signs/symptoms of bacterial invasion and toxin production
Septicemia
how is septicemia diagnosed?
blood cultures
Systemic response to infection sometimes accompanied by organ involvement
Sepsis
Sepsis accompanied by hypotension
Septic shock
which bacteria produce endotoxins?
gram negative, mainly bacilli but some cocci
what affects can endotoxin have when released into the blood?
Disseminated intravascular coagulation – death is coming
Stops peripheral circulations and forces blood to major organs
how can antibiotics make sepsis worse?
if gram negative bacteria is lysed by wbc – endotoxin is released. Some Antibiotics are detrimental. Has toxic affects
Need antibiotics that prevent protein production and prevent multiplying. Not use broad spectrum
what are common disease causes of sepsis?
Meningitis. Pneumonia. Urinary tract infection.
Osteomyelitis. Gut related infection.
Cellulitis and necrotising fasciitis
what the common mechanical disruption of host defenses causing sepsis?
Intravascular catheters
Urinary catheters
how do these things lead to septicemia?
Previous infections migrate into the blood stream
Primary bacteremia
- arises from endovascular source
- i.e., patient with pneumonia gets into bloodstream
Secondary bacteremia
- arises from extravascular source
- i.e., catheters
Classification of Bacteremia by site of origin
Primary Bacteremia
Secondary Bacteremia
Bacteremia of Unknown Origin
Classification of Bacteremia by Causative agent
- Gram-positive bacteremia: S. pneumo, S. aureus, Enterococcus faecium
- Gram-negative bacteremia: E. coli, P. aeruginosa, B. frag
- Polymicrobial bacteremia (IV drug use, burns, GI sources)
Classification of Bacteremia by Place of Acquisition
- Community-acquired bacteremia: S. pneumo
- Nosocomial bacteremia: P. aeruginosa, Enterococcus
Classification of Bacteremia by Duration
- Transient bacteremia: result of procedure, caused by flora
- Intermittent bacteremia: result of abscess (meningococcemia, gonococcemia)
- Continuous bacteremia: intravascular source, continuously present, i.e., prosthetic heart valve
Bacteremia (risk factors)
- immune competency
- increased use of invasive procedures increases risk
- age (very young and old at higher risk)
- antimicrobials: broad spectrum reduce normal flora
Bacteremia (causative agents)
- in the past: E. coli, P. aeruginosa, S. aureus, CoNS, Enterococcus
- recently: fungemias (Candida albicans, malassesia furfur)
- associated with community-acquired illness
- Optochin S, Sodium desoxycholate +
- capsule, IgA protease
S. pneumoniae
- UTI’s, bacteremia, other infections
- catalse +, coagulase +
- hyaluronidase, latex +
S. aureus
- blue/green on MAC
- oxidase +, glucose oxidizer, 42C
- capsule, motile, associated with nosocomial infection
- CF patients pneumonia
- Hot tub syndrome
P. aeruginosa
- # 1 colon flora, anaerobic
- tolerates bile
- vancomycin, kanamycin, colistin resistant
B. fragilis
Antimicrobial resistant bacteremia agents
- MRSA
- VRE (Vancomycin-resistant Enterococcus)
- ESBL (Extended spectrum beta lactamases)
Vaccine reduction of bacteremia
Hib and S. pneumoniae vaccines
Bateremia (pathogenesis)
- Disruption of skin or mucosa gives bacteria access to microvasculature
- Complications are metastatic infection (infection to multiple sites) and septic shock
Clinical syndromes associated with bacteremia
- Catheter-related bloodstream infections: S. epi, Enterococcus, S. aureus
- UTI’s: E. coli, common in elderly
- Pneumonias: S. pneumo, H. flu, S. aureus, P. aeruginosa
- Intraabdominal infections: primary and secondary peritonitis (E. coli, Kleb. pneumo, Enterococcus)
- Skin infections: bed ridden patients and diabetics
- Infective endocarditis: CoNS, Viridans strep, S. aureus
- Musculoskeletal infections: bone capillaries, prosthetic joints
Bacteremia (Symptoms/Lab findings)
- Shaking, chills, fever, hypotheremia
- Thrombocytopenia, Leukocytosis or Leukopenia, Lactic acidosis, hypoglycemia or hyperglycemia
- Abnormal liver function tests
- coagulopathy
- DIC, elevated C-reactive protein, haptoglobin, fibrinogen
Blood culture contaminants
- CoNS, Corynebacterium, Bacillus, alpha hemolytic strep, Propionibacterium acnes
- skin flora contamination is expected (2-3%)
- should be < 3%, from one site
Blood Culture Collection (other concerns)
- 3 collections are recommended
- ideally collected before temperature rise in intermittent
- single blood cultures are not acceptable
Bacteremias that must be followed with Blood Cultures
- infective endocarditis
- S. aureus bacteremia
Blood culture medium
- Nutrient broth with SPS (anticoagulant)
- incubate at 37C for 5 days
BACTEC
- automated method
- measures CO2 production from microbe metabolism
BacT/ALERT
- automated method
- measures CO2 derived pH changes by colorimetric sensor
