Bacteremia: Difference between revisions
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==Background== | ==Background== | ||
Bacteremia is presence of bacteria in the blood, which is typically a sterile environment. This is distinct from sepsis, which is the body's response to the infection. | Bacteremia is presence of bacteria in the blood, which is typically a sterile environment. This is distinct from [[sepsis]], which is the body's response to the infection. | ||
*Primary bacteremia is the result of direct inoculation of bacteria into the bloodstream. Most commonly the result of IV drug use or contaminated venous catheters | *Primary bacteremia is the result of direct inoculation of bacteria into the bloodstream. Most commonly the result of [[IV drug use]] or contaminated [[central line|venous catheters]] | ||
*Secondary bacteremia occurs when bacteria enters via an alternate site such as cuts in the skin, mucous membranes, or genitals | *Secondary bacteremia occurs when bacteria enters via an alternate site such as cuts in the skin, mucous membranes, or genitals | ||
===Risk Factors=== | ===Risk Factors=== | ||
*Diabetes | *[[Diabetes]] | ||
*HIV infection | *[[HIV infection]] | ||
*Hemodialysis | *[[Hemodialysis]] | ||
*Immunosupression | *Immunosupression | ||
*Glucocorticoid therapy | *[[Glucocorticoid]] therapy | ||
*IV drug use | *[[IV drug use]] | ||
===Common Pathogens=== | ===Common Pathogens=== | ||
*[[Staph aureus]] is one of the most common cause of bacteremia in healthcare setting | *[[Staph aureus]] is one of the most common cause of bacteremia in healthcare setting | ||
*Gram negative bacteremia accounts for a quarter to half of bloodstream infections. | *[[Gram negative]] bacteremia accounts for a quarter to half of bloodstream infections. | ||
**The most common isolated pathogens include [[E. coli]], [[K. pneumonia]], [[P. aeruginosa]], [[Proteus]] spp. | **The most common isolated pathogens include [[E. coli]], [[K. pneumonia]], [[P. aeruginosa]], [[Proteus]] spp. | ||
*[[Group A strep]] accounts for 0.6% of bacteremia. | *[[Group A strep]] accounts for 0.6% of bacteremia. | ||
**May indicate undiagnosed type II [[necrotizing fasciitis]] | |||
==Clinical Features== | ==Clinical Features== | ||
A host response may result in sepsis | A host response may result in [[sepsis]] | ||
*Typically present with fever, chills and hypotension. | *Typically present with fever, chills and hypotension. | ||
*The presence of chills is also independently associated with blood stream infections | *The presence of chills is also independently associated with blood stream infections | ||
Alternatively bacteria may spread hematomagously to distant sites in body: | Alternatively bacteria may spread hematomagously to distant sites in body: | ||
*Endocarditis | *[[Endocarditis]] | ||
*Meningitis | *[[Meningitis]] | ||
*Osteomyelitis | *[[Osteomyelitis]] | ||
==Differential Diagnosis== | ==Differential Diagnosis== | ||
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==Evaluation== | ==Evaluation== | ||
===Source=== | ===Source=== | ||
*In gram positive bacteremia, more notably Staph aureus, consider sources from skin ulcerations, respiratory tract infections, IV drug use, and indwelling catheters | *In [[gram positive]] bacteremia, more notably [[Staph aureus]], consider sources from skin ulcerations, respiratory tract infections, [[IV drug use]], and indwelling catheters | ||
*In gram negative bacteremia, common sources include respiratory tract and central venous catheters. In the elderly, consider urinary tract infections. | *In [[gram negative]] bacteremia, common sources include respiratory tract and central venous catheters. In the elderly, consider urinary tract infections. | ||
===Blood Cultures=== | ===Blood Cultures=== | ||
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*[[Gram negative]] bacteremia should be treated via empirical therapy based on suspected source | *[[Gram negative]] bacteremia should be treated via empirical therapy based on suspected source | ||
*Catheter associated infections | *Catheter associated infections | ||
**Short term catheters(<14 days) should be removed if cause of bacteremia, especially [[gram negative]], [[staph aureus]], [[enterococci]], or [[mycobacteria]] | **Short term catheters (<14 days) should be removed if cause of bacteremia, especially [[gram negative]], [[staph aureus]], [[enterococci]], or [[mycobacteria]] | ||
**Long term catheters(>14 days) should be removed if patient is septic or bacteremia persists for 72+ hours | **Long term catheters (>14 days) should be removed if patient is septic or bacteremia persists for 72+ hours | ||
===Resistance=== | ===Resistance=== | ||
*Extended spectrum beta lactam resistance - drugs of choice include those in the [[ | *Extended spectrum beta lactam resistance - drugs of choice include those in the [[carbapenem]] family of antibiotics | ||
* | *Carbapenem resistance - usually requires a combination regimen of two or more | ||
==Disposition== | ==Disposition== | ||
Latest revision as of 02:35, 11 January 2022
Background
Bacteremia is presence of bacteria in the blood, which is typically a sterile environment. This is distinct from sepsis, which is the body's response to the infection.
- Primary bacteremia is the result of direct inoculation of bacteria into the bloodstream. Most commonly the result of IV drug use or contaminated venous catheters
- Secondary bacteremia occurs when bacteria enters via an alternate site such as cuts in the skin, mucous membranes, or genitals
Risk Factors
- Diabetes
- HIV infection
- Hemodialysis
- Immunosupression
- Glucocorticoid therapy
- IV drug use
Common Pathogens
- Staph aureus is one of the most common cause of bacteremia in healthcare setting
- Gram negative bacteremia accounts for a quarter to half of bloodstream infections.
- The most common isolated pathogens include E. coli, K. pneumonia, P. aeruginosa, Proteus spp.
- Group A strep accounts for 0.6% of bacteremia.
- May indicate undiagnosed type II necrotizing fasciitis
Clinical Features
A host response may result in sepsis
- Typically present with fever, chills and hypotension.
- The presence of chills is also independently associated with blood stream infections
Alternatively bacteria may spread hematomagously to distant sites in body:
Differential Diagnosis
Evaluation
Source
- In gram positive bacteremia, more notably Staph aureus, consider sources from skin ulcerations, respiratory tract infections, IV drug use, and indwelling catheters
- In gram negative bacteremia, common sources include respiratory tract and central venous catheters. In the elderly, consider urinary tract infections.
Blood Cultures
- Obtain blood cultures prior to antibiotic therapy. Indicated for suspected bacterial infections or elevated white count.
- Care should be taken to avoid contamination of samples with skin flora
- If filling serial samples from same syringe, fill aerobic(blue) tube first to draw out air in the needle before filling the anaerobic(orange) tube
Echocardiography
- Patients should undergo cardiac echo if staph aureus bacteremia is found to look for endocarditis
Management
- Uncomplicated MRSA with 14 days of IV vancomycin
- Gram negative bacteremia should be treated via empirical therapy based on suspected source
- Catheter associated infections
- Short term catheters (<14 days) should be removed if cause of bacteremia, especially gram negative, staph aureus, enterococci, or mycobacteria
- Long term catheters (>14 days) should be removed if patient is septic or bacteremia persists for 72+ hours
Resistance
- Extended spectrum beta lactam resistance - drugs of choice include those in the carbapenem family of antibiotics
- Carbapenem resistance - usually requires a combination regimen of two or more
Disposition
- Admit