export_circulatory bacteria Flashcards
Bacteremia
Bacteria in the blood
What are the most common causes of bacteremia?
UTIs
RTIs
Skin/soft tissue infections
Consequences of bacteremia
Transient and benign
Can result in sepsis/septic shock or endocarditis
Sepsis
Systemic inflammatory response syndrome (SIRS) with a suspected microbial etiology (i.e. SIRS with an infection)
Sepsis causes
Bacteremia OR
Bacteria releasing toxins into the blood
SIRS symptoms
Fever OR hypothermia
Tachypnea
Tachycardia
Abnormal WBCs
Severe sepsis
Sepsis with one or more signs of organ dysfunction (reduced urine output, systemic acidosis, etc.)
Septic shock
Severe sepsis with hypotension
Refractory septic shock
Septic shock that lasts more than 1 hour and does not respond to fluids/drugs
Multiorgan failure
Dysfunction of more than one organ and development of DIC
What microbial agent most commonly causes sepsis and septic shock?
Bacteria
Bacteremia NOT required
Pathophysiology of sepsis/septic shock
Gram-negative (LPS or Lipid A)
Gram-positive (TSST-1)
Teichoic acid of Staph.
Capsule of S. pneumoniae
Polysaccharides of C. albicans
How does LPS cause inflammation?
Binds to CD14 and TLR4 on APCs
Results in inflammatory response (TNF, IL-1, IL-6)
S. aureus features
Catalase positive
Coagulase positive
Facultative intracellular
TSST-1 features
Heat and proteolysis-resistant
Can penetrate mucosal barrier
Superantigen
Strep. toxic shock syndrome features
Most patients have bactermia
Many have necrotizing fasciitis
Production of pyogenic exotoxins (SPEs)
SPE features
Superantigen
Diagnose sepsis
Blood cultures
Treat sepsis
IV fluids for hypotension
Platelets to stop DIC
Antimicrobial therapy
Antimicrobial therapy for sepsis
Vancomycin and gentamycin if unknown
Where do most endocarditis infections occur?
On natural or prosthetic cardiac valves
Acute endocarditis
High fever
Rapid damage to cardiac structures
Progresses to death quickly
Often caused by S. aureus
Subacute endocarditis
Low grade fever
Night sweats
Weight loss
Slower damage to heart
Most commonly caused by Viridans strep. (less virulent)
Other symptoms of endocarditis
New or unchanging heart murmur
Splenomegaly
Various skin lesions
Retinal lesions
Janeway lesions
Painless lesions on palms or soles of feet
Osler nodes
Painful subcutaneous nodules in the pads of digits
Streptococcus features
Gram-positive cocci in chains
Catalase negative
Viridans streptococci features
Large group of commensal bacteria
Associated with subacute endocarditis
Alpha or gamma hemolytic
Resistant to optochin
Common Viridans streptococci species
S. mitis
S. salivarius
Pathophysiology of endocarditis
Vegetations (composed of platelets, fibrin, bacteria, and inflammatory cells)
These will damage the heart and result in death if not treated
Diagnose endocarditis
Positive blood culture
Evidence of endocardial involvement
Fever, vascular phenomenon, etc.
Endocarditis treatment
Aggressive antimicrobial therapy, that is prolonged (i.e. longer than 4 weeks)
