Bacteremia

Bacteremia

Presence of viable bacteria in the bloodstream

Septicemia

Outdated term historically describing bacteremia with systemic symptoms

Sepsis

Life-threatening organ dysfunction caused by a dysregulated host response to infection

Septic shock

Severe sepsis with persistent hypotension and organ failure

Transient bacteremia

Short-lived bacteremia often caused by procedures such as tooth brushing or endoscopy

Intermittent bacteremia

Periodic release of bacteria into the bloodstream from localized infections

Continuous bacteremia

Constant presence of bacteria in blood usually due to endocarditis or suppurative thrombophlebitis

Condition associated with transient bacteremia

Dental procedures or cellulitis

Condition associated with intermittent bacteremia

Pneumonia, urinary tract infection, or osteomyelitis

Condition associated with continuous bacteremia

Infective endocarditis

Clinical presentation of bacteremia

Often asymptomatic or mild symptoms with possible positive blood cultures

Clinical presentation of sepsis

Fever or hypothermia, tachycardia, tachypnea, and malaise

Clinical presentation of septic shock

Hypotension, altered mental status, and multi-organ dysfunction

Most common cause of bacteremia

Staphylococcus aureus and Escherichia coli

Other common bacteremia pathogens

Pseudomonas aeruginosa and streptococcal species

Most common fungal bloodstream pathogen

Candida species

Blood culture contamination definition

Growth of nonpathogenic skin or environmental flora in blood cultures

Common blood culture contaminants

Coagulase-negative staphylococci, Corynebacterium species, Micrococcus species, viridans streptococci

Indicator of blood culture contamination

Only one bottle in a set is positive

Normal flora of blood

None, blood is a sterile site

Blood culture principle

Any positive blood culture is clinically significant until proven otherwise

Recommended blood culture volume per set

20 mL total blood per set

Blood culture bottle distribution

10 mL aerobic and 10 mL anaerobic

Number of blood culture sets per 24 hours

Two to three sets

Total blood volume recommended

40–60 mL of blood

Timing of blood culture collection

Before antibiotic therapy is started

Importance of blood volume

Most critical factor for detecting bacteremia

Reason not to draw from IV lines

Risk of contamination and antibiotic interference

Automated blood culture system example

BD BACTEC

Automated blood culture detection method

Monitoring carbon dioxide production

Culture monitoring frequency

Approximately every 10 minutes

Standard blood culture incubation time

Five days

Definition of infective endocarditis

Infection of the endovascular surfaces of the heart

Most common site of endocarditis

Heart valves

Common symptoms of endocarditis

Fever, malaise, night sweats, myalgia

Most common endocarditis pathogens

Gram-positive cocci

Staphylococcus aureus in endocarditis

staph- Approximately 30 percent of cases

Streptococcus species in endocarditis

strep- Approximately 30 percent of cases

HACEK organisms

Haemophilus, Aggregatibacter, Cardiobacterium, Eikenella, Kingella

HACEK infection characteristic

Fastidious gram-negative organisms causing endocarditis

Risk factors for endocarditis

Prosthetic valves, congenital heart disease, immunosuppression, IV drug use, indwelling catheters

Endocarditis risk in immunocompromised patients

Increased due to foreign material and impaired immunity

Suppurative thrombophlebitis definition

Venous thrombosis with associated bacteremia

Common causes of suppurative thrombophlebitis

IV catheters, IV drug use, severe burns

Most common organisms in suppurative thrombophlebitis

Staphylococcus aureus, Streptococcus pyogenes, enteric gram-negative rods, Candida species

Lemierre syndrome

Suppurative thrombophlebitis of the jugular vein

Causative agent of Lemierre syndrome

Fusobacterium necrophorum

Route of IV catheter infection

Skin insertion site contamination

Route of catheter hub infection

Contamination of catheter access point

Route of hematogenous catheter infection

Bacteria in bloodstream adhering to catheter

Lab method to detect catheter infection

Catheter tip culture

Time to positivity significance

Shorter time suggests catheter-associated infection

Requirement for catheter infection diagnosis

Simultaneous peripheral blood culture

Risk factors for bacteremia

Indwelling catheters, surgery, trauma, burns, immunosuppression

Risk factors for bloodstream infection in neonates

Immature immune system and invasive procedures