This document discusses bloodstream infections, including definitions, types, causes, and trends. It defines terms like bacteremia, sepsis, and community-acquired versus nosocomial bloodstream infections. Primary bloodstream infections often originate from intravascular devices, while secondary infections usually stem from a focus elsewhere in the body. Common pathogens have changed over time and vary based on healthcare or community setting. Prompt diagnosis and treatment are important given the high mortality rates associated with severe sepsis and septic shock.

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