Chap 36-BOOK (Part 1) Flashcards
Presence of viable bacteria in the blood stream
Bacteremia
Bacteremia is often associated with
Hospitalization
Insertion of foreign bodies such as catheter into blood vessels
Blood cultures may also be positive as a result of contamination of blood samples during phlebotomy, leading to false-positive results, a phenomenon termed
Pseudobacteremia
Contamination is most often caused by skin commensals
CONS (Coagulase negative staphylococci)
A blood culture reflects a true-positive result, bacteremia may not be associated with any physical signs or symptoms of severe infection, a condition known
Occult (unsuspected) bacteremia.
occult (unsuspected) bacteremia is most often caused by
Strep. pneumoniae
indicate bacteremia plus a clinical presentation of physical signs and symptoms of bacterial invasion and toxin production
Septicemia
Comprises a spectrum of increasingly severe conditions ranging from noninfectious inflammatory response to sepsis
Systemic inflammatory response syndrome (SIRS)
Sepsis accompanied by refractory hypotension
Septic shock
Site of origin of Primary bacteremia
Endovascular source (Infected cardiac valve or IV catheter)
Secondary bacteremia occurs in
Infected extravascular souce (Lung in patients with pneumonia)
Gram-positive bacteremia is caused by organisms
Streptococcus pneumoniae
Staphylococcus aureus
Enterococcus faecium
Gram-negative bacteremia is caused by
Escherichia coli or Pseudomonas aeruginosa
Anaerobic bacteremia is caused by
B. fragilis
Type of bacteremia that is caused by mixture of organisms
Polymicrobial bacteremia
usually occurs after a procedural manipulation of a particular body site
Transient bacteria
Occur because of the presence of abscesses somewhere in the body or as a clinical manifestation of certain types of infections, such as meningococcemia, gonococcemia, or pneumonia.
Intermittent bacteremia
Occurs when the organisms are coming from an intravascular source and are consistently present in the bloodstream
Continuous bacteremia
Most common clinical manifestation associated with continuous bacteremia
Infective endocarditis
The agent of first case of bacteremia in 1899
Pseudomonas aeruginosa
Factors associated with an unfavorable outcome in bacteremia
- Age older than 70 years
- Polymicrobial bacteremia
- Presence of malignancy
- Acquired immunodeficiency syndrome (AIDS), or renal failure
- Origin of the bacteremia in the respiratory tract or bowel
- Unknown origin of bacteremia
- Inappropriate antimicrobial therapy.
Risk factors of bacteremia
- Decreased immune competency of selected patient populations
- Increased use of invasive procedures
- Age of the px
- Antimicrobial resistance
- Diagnostic criteria and coding practice
Bacteremias are more frequent among persons with
- Neoplasia (abnormal growth of new cells that maybe benigh or malignant)
- Chronic underlying dse
- Receiving immunosuppresive therapy)
- HIV
58% of S. aureus isolates in the United States were resistant to
Methicillin (Oxacillin)
30% of Enterococcus was resistant to
Vancomycin
15% of Klebsiella spp. were extended-spectrum
β-lactamases (ESBL) producers
9% of E. coli isolates were resistant
Ciprofloxacin
Bacterial invasion of the bloodstream, cases attributable to fungal invasion of the bloodstream (fungemia) caused by organisms such as
C. albicans
The predisposing factors in polymicrobial bacteremia include
IV drug use, burns, and GI tract sources
May lead to bacteremia via local inflammation, edema, and tissue destruction that disrupts nearby vascular structures and allows bloodstream invasion.
Focal bacterial infection
Two major complications may ensue:
Metastatic infection and septic shock
S. aureus bacteremia may lead to
Endocarditis, osteomyelitis, septic arthritis, hepatic abscess, or pyomyositis.
A bacterial membrane component (lipopolysaccharide [LPS], also known as endotoxin, in gram- negative organisms; lipoteichoic acid and peptidoglycan in gram- positive organisms) interacts with macrophages
causes release of tumor necrosis factor, IL1, IL6 and other proinflammatory cytokines
Catheters exquisitely vulnerable to colonization and biofilm formation by gram-positive organism
CoNS, S. aureus, and Enterococcus
May serve as a ligand during initial surface adhesion and colonization, or it may be produced after the organism has established a focal presence by adhering to the surface
Biofilm
Organisms associated with such infusion-associated bacteremias are typically gram-negative organisms such as
P. aeruginosa and Enterobacter cloacae.
Bloodstream infections caused by nontuberculous mycobacteria associated with intravascular catheters by
Mycobacterium aviumintracellularae complex HIV-positive individuals
Most common cause of bacteremia in UTI
E. coli
Most common organisms in pneumonia that produce a concurrent bacteremia
S. pneumoniae, H. influenzae, S. aureus, P. aeruginosa, and E. aerogenes.
Primary peritonitis, which frequently occurs in patients with cirrhosis is caused by
E. coli, K. pneumoniae, and enterococci
Secondary peritonitis is caused by
E. coli, anaerobes, and enterococci.
Cellulitis caused by
S. aureus, Streptococcus pyogenes, or Streptococcus agalactiae
Skin breakdown in bedridden patients (bed sores) or peripheral vascular disease can be caused by
Proteus mirabilis, E. coli, S. aureus, B. fragilis, Pseudomonas spp., Clostridium spp., and Peptostreptococcus
Organisms associated with acute, sudden- onset endocarditis include virulent bacteria such as
S. aureus and S. pneumoniae
Progressing subacute endocarditis is commonly caused by less virulent bacteria
iridans streptococci, nutritionally variant streptococci (Abiotrophia and Granulicatella, and CoNS)
Acute osteomyelitis is often associated with transient bacteremia caused by
S. aureus
Prosthetic joints, particularly those implanted in the hip, can be hematogenously seeded by organisms such as
S. aureus and CONs
Prosthetic joint infection with virulent organisms such as S. aureus or group A β-hemolytic streptococci can lead to
florid sepsis and death
Acute bacterial meningitis is generally the result of transient bacteremia caused by
S. pneumoniae or Neisseria meningitidis
Meningitis is caused by bacteremia resulting from sinusitis or otitis caused by
S. pneumoniae
abnormal rapid breathing
Tachypnea
A central necrotic area surrounded by an erythematous base, is typically associated with Pseudomonas bacteremia.
Ecthyma gangrenosum
A central necrotic area surrounded by an erythematous base, is typically associated with Pseudomonas bacteremia.
Ecthyma gangrenosum
