Table 1. Organisms Associated with Nosocomial Catheter-Related Blood Stream Infections (CR-BSI).

Organism

Comments

Coagulase-negative Staphylococci

Most common pathogen in CR-BSI

Staphylococcus aureus

Increasing prevalence of MRSA strains

Gram-negative bacilli

Among the resistant gram negative bacilli, Acinetobacter baumannii predominates in Europe. In USA Pseudomonas aeruginosa seems to be more prevalent

Enterococcus spp.

E. faecalis is more common than e. faecium

Candida spp

C. albicans is the most common species

Other bacteria including diphteroids, viridans streptococci, Micrococcus, and more rarely, fungi other than Candida spp.

 

The organisms are listed in order of decreasing frequency. From multiple sources (6, 9,11, 20, 21)
 

Table 2:  Risk Factors for Bacteremia

·         Advanced age

·         Corticosteroids

·         Immunosuppressing medications (transplant patients, rheumatologic diseases, etc)

·         Chronic liver disease

·         Chronic renal failure (especially if on hemodialysis)

·         Hematological malignancies

·         HIV infection

·         Intravenous catheters

·         Intravenous drug use

·         Loss of skin integrity

·         Malnutrition and hypoalbuminemia

·         Neutropenia

·         Parenteral nutrition

 

 

Table 3. Contamination versus True Infection Rates for Specific Organisms.

Organism

False positives

Bacillus spp.

>90%

Coag-negative Staphylococcus spp.

>90%

Propionibacterium spp.

>90%

Corynebacterium spp.

>80%

Viridans streptococci

50%

Clostridium spp.

40%

Staphylococcus aureus spp.

25%

Enterococcus spp.

15%

Source. From a presentation by Dr. Patric Murray, University of Maryland School of Medicine.

Microbiology for the Millennium Conference. Feb. 17-19, 1999. Baltimore, MD


Table 4.  Organisms Causing Nosocomial Blood Stream Infections by Frequency.

Organism

Percent of BSI

Coagulase-negative Staphylococcal spp.

31.3%

Staphylococcus aureus

20.2%

Enterococcus spp.

9.4%

Candida spp.

9.0%

Escherichia coli

5.6%

Klebsiella spp.

4.8%

Pseudomonas aeruginosa

4.3%

Enterobacter spp.

3.9%

Serratia spp.

1.7%

Acinetobacter baumannii

1.3%

Reference [11]

 

 

Table 5. Risk Factors for Infective Endocarditis

Non-cardiac

Cardiac

·         IV drug abuse

·         Male

·         Advancing age

·         Recent dental surgery or other invasive procedures

·         Nosocomial bacteremia

·         Permanent venous access lines

·         Surgically constructed pulmonary shunts

·         Degenerative valvular lesions

·         Congenital heart disease

·         Prosthetic valves

·         Mitral valve prolapse with insufficiency

·         Rheumatic heart disease

·         Previous infective endocarditis

·         Hypertrophic cardiomyopathy
 


Table 6: Risk Factors for Gram Negative Bacilli Bacteremia

  • Hematopoietic stem cell transplant

  • Liver failure

  • Serum albumin <3 mg/dL

  • Solid organ transplant

  • Diabetes

  • Pulmonary disease

  • Hypotension

  • Hemodialysis

  • HIV

  • Hematologic malignancy

  • Steroids

  • Elderly

 

 

  

 

 Table 7. Characteristics of the Major Candida spp.

Species

Frequency

Virulence

Clinical Associations

C. albicans

42% - 65%

High

Most common in all settings

C. tropicalis

11% - 25%

High

Cancer

C. glabrata

7% - 15%

Low

Cancer

C. parapsilosis

7% - 18%

Variable

Plastic devices, hyperalimentation

C. krusei

1% - 4%

Low

Cancer

C. lusitaniae

1% - 2%

Low

Cancer

Shown are frequency estimates for the species causing invasive disease.

 

 

Table 8. Primary and Alternative Empiric Antibiotic Choices for Bacteremia

 

Primary

Alternative

Gram-positive cocci in clusters*

Vancomycin OR daptomycin^

Nafcillin OR cefazolin (once MRSA ruled out)

 

Gram-positive cocci in chains

Ampicillin OR vancomycin

Ceftriaxone** OR daptomycin

 

Gram-negative bacilli in a clinically unstable patient, immunosupressed, history of malignancy or a patient with health care associated infection

 

Cefepime +  ciprofloxacin (or tobramycin) OR piperacillin/tazobactam +  ciprofloxacin (or tobramycin)

Aztreonam +  tobramycin (or ciprofloxacin OR imipenem +  ciprofloxacin (or tobramycin)

Gram-negative bacilli in a clinically stable patient

 

Ceftriaxone OR piperacillin/tazobactam

Aztreonam OR ciprofloxacin

Anaerobes

Piperacillin/tazobactam OR metronidazole

 

Clindamycin OR Imipenem

Candida sp.

Echinocandin OR voriconazole

Fluconazole” OR Amphotericin B

^daptomycin not indicated if patient clinically has pneumonia.

*consider the addition of a second agent such as gentamicin if patient is clinically unstable or endocarditis is likely

**Do not use if enterococcus is a potential cause of infection

“May be used as a first line agent when patient is hemodynamically stable and no previous azoles administered

 

Figure 1: Staphylococcal spp. are Always Catalase Positive while Streptococcal spp. are Catalase Negative

 

Figure 2: Classification of Gram Negative Bacilli

Figure 3. Algorithm for the Treatment of Candidemia