representative infections in health systems due to gram positive pathogens Flashcards
define bacteremia
viable bacteria in the blood
bacteria in the blood becomes a bloodstream infection when _____
immune response mechanisms fail or are overwhelmed
what is CRITICAL with bacteremia
determining the primary source of the infection— may be the cause or consequence of another infection
what is the common etiology of hospital-acquired bacteremia
respiratory tract and indwelling catheters (central venous catheters)
what is the common etiology of community-acquired bacteremia
untreated UTIs
what is the common etiology of post-operative bacteremia
soft tissue and intraabdominal infections
what gram positive pathogen most commonly causes bacteremia
staphylococcus aureus
why has gram positive bacteremia increased over past decades
aging population, device-related procedures
which is most commonly associated with community-acquired bacteremia: gram positive or gram negative? and which pathogen is most common?
gram negative– escherichia coli is most common
bacteremia pathophysiology: reproducing bacteria may lead to septicemia with failure of _____ (2 things)
- cellular innate & adaptive immune responses responsible for initial microbe clearance
- liver and spleen filtration of active bacteria in the circulating blood
what are some complications of bacteremia
endocarditis, osteomyelitis, pneumonia, cellulitis, meningitis, progression to sepsis, multiorgan dysfunction that can be fatal
what is the classical presentation of bacteremia
fever.
chills/rigors do not need to be present, but indicate bacteremia
when bacteremia leads to sepsis and septic shock, it commonly causes ____
hypotension, altered mental status, and decreased urine output due to hypovolemia from leaky capillaries. other organs can become affected as the infection disseminates
diagnosis of bacteremia
IDENTIFY THE SOURCE
Initial labs in all bacteremic patients should include blood cultures: ideally 2 sets assessing for aerobic and anaerobic organisms from each arm
WBC are often elevated (non specific)
general approach to treatment for bacteremia ?
URGENT– delay associated with increased morbidity and mortality
APPROPRIATE antibiotics– broad spectrum, bactericidal, high dose, empiric antibiotics
antibiotic selection for bacteremia is based on
community or hospital acquired
recent healthcare exposure or surgery?
local antibiotic resistance (antibiogram)
rapid diagnostic tools
what antibiotic route is preferred for bacteremia
IV preferred initially
Oral when afebrile for greater than 48 hours, clinically improved and stable unless complicated by another infections, highly bioavailable drugs
what is the duration of treatment for bacteremia
based on source and source control
gram positive bacteria may range up to 14 days
if complicating infections present may be 4-6 weeks or longer
when does the clock start for duration of therapy for bacteremia
from the first sterile blood culture and/or source control
how to evaluate therapeutic outcomes for bacteremia (clinical, microbiological)
clinical: resolved signs & symptoms, source control, drug specific toxicity, no complicating infections
microbiological: susceptibility data, sterilization of blood cultures
classifications of infective endocarditis
acute or subacute, native or prosthetic valve, community or healthcare acquired, by microbiological etiology
impact of infective endocarditis
high mortality, fatal without antimicrobial therapy, staph. aureus associated with healthcare and acute bacterial
risk factors for infective endocarditis
predisposing heart conditions, people who inject drugs
what predisposing heart conditions are high risk per AHA (name 4)
- an artificial (prosthetic) heart valve, including bioprosthetic and homograft valves
- previous bacterial endocarditis
- complex cyanotic congenital heart disease
- surgically constructed shunts or conduits