1. BLOOD STREAM
INFECTIONS:Definitions and
Significance.
Dr Abhijit Chaudhury

2. Classical Terms
 Bacteremia: Presence of Bacteria in blood.
Transient: Manipulation/Surgery in
infected/colonized area
Intermittent: Abdominal/Pelvic abscess
Continuous: Endocarditis/Intravascular
infections/ First week of Typhoid , Brucellosis.
 Septicaemia:
toxins in blood.
Presence of microbes or their

3. Recently Introduced Terms
BLOOD STREAM INFECTION: Presence
and active multiplication of organisms
in blood.
 Primary: Point of entry or focus of
infection cannot be determined/
Originates from I/V catheters.
 Secondary: Distant site (focus) of
infection present.

4.  Community acquired BSI: Those
Detected within 48 hrs of admission
 Nosocomial BSI: Signs and
symptoms detected after 48 hrs of
admission

5. SEPSIS SPECTRUM
Consensus Committee of American Experts (1992)
Definitions:
Systemic Inflammatory Response Syndrome (SIRS)
:Systemic response to a wide range of stresses.
Two or more of the following:
Temperature : > 380 C or < 360 C
Heart Rate > 90/min
Tachypnea > 20 /min or Hyperventilation
(PaCO2 <32 mm Hg, 4.3kPa)
Leukocytes > 12,000 or < 4,000/mm3 or
> 10% immature neutrophils

6. Sepsis Spectrum

7. Limitations of SIRS Definition

9. Sepsis Spectrum and Mortality
Incidence
Mortality
Sepsis
400,000
7-17%
Severe Sepsis
300,000
Approximate
ly 200,000
patients
have septic
shock
annually
20-53%
Septic
Shock
53-63%
Balk, R.A. Crit Care Clin 2000;337:52

10. Bacteremia in the Preantibiotic
Era






Streptococcus pneumoniae
Group A Streptococcus
Staphylococcus aureus
Salmonella spp
Haemophilus influenzae
Neisseria meningitidis

11. CHANGING TRENDS
IN PATHOGEN
PATTERN IN BSI.
a. Nosocomial BSI
b. Community Acquired
BSI

12. PRIMARY
BLOOD STREAM INFECTION
 In many cases the primary focus/ route of
entry remains unknown (Appx. 20%)
 Therapeutic/Diagnostic medical devices
coming in direct contact with blood(Device Related Bacteremia ,Maki 1977).
 Various types of venous catheters, arterial
lines - Catheter Related BSI (CR-BSI).
 Entry of organisms through:
1. Contamination of Infusate
2. Contamination of Catheter hub and lumen
3. Contamination of Skin at insertion site

14. CR-BSI, S.aureus Bacteremia
Jensen AG. Journal Hospital Infection 2002;52:29-36

15. Secondary BSI
 Focus of Infection most commonly in
LUNGS, URINARY TRACT, ABDOMEN,
INFECTED SURGICAL SITE.
 Gram negative pathogens more
commonly involved.
 5-12% cases may be due to fungi,
particularly Candida.

16. Predisposing Conditions and Agents
in BSI.
GRAM NEGATIVE PATHOGENS:
 Diabetes mellitus
 Lymphoproliferative diseases
 Liver cirrhosis
 Burns
 Invasive procedures or devices
 Neutropenia
 Indwelling urinary catheter

17. Predisposing Conditions-GRAM POSITIVE PATHOGENS:
 Intravascular Catheters
 Indwelling mechanical devices
 Burns
 Neutropenia
 Intravenous drug users
FUNGI:
 Neutropenia
 Broad spectrum antimicrobial therapy

18. Neonatal BSI
 Commonly manifests as meningitis, almost
always preceded by bacteremia.
 Risk Factors: Prematurity, low birth weight,
premature rupture of membrane, prolonged
labour.
 Mortality: 30-40%, Permanent
defects:30% of survivors.
 Gram negative bacteria: E.coli, Klebsiella,
Enterobacter etc.
 Gram Positive: Group B Streptococcus
(S.agalactiae), Listeria.

19. Conclusion



Sepsis may be obvious or subtle early in its course.
There is a high mortality and morbidity
Clinical characteristics






Community-acquired vs. hospital acquired
Presence or absence of an apparent primary focus.
Role of intravascular catheters: Diagnosis of exclusion or
laboratory criteria
Take appropriate cultures
Treatment
1.Need to initiate empiric therapy
2.Choice of initial therapy depends on Knowledge of local
organisms / susceptibilities
Aggressive management is crucial in determining the
patient’s survival.
THE END