Nosocomial Infections

1
Nosocomial Infections

• Refers to infections ACQUIRED in hospital
• Incubation period ?
• Working definition is gt 72 hrs
• Impact of nosocomial infections
• Increased morbidity, mortality, LOS and cost

MJA 1995 10 of 4 M annual admissions in Aus
contract an infection. 400 000 infections and 600
deaths.
2
Why so many infections? Why are they different?
Exposure and opportunity for transmission
Host susceptibility
NOSOCOMIAL INFECTION
Hospital microorganisms
3
Host Susceptibility

• Healthy people dont go to hospital?
• Decreased general health
• Less mobile
• Breaks in primary defense - pressure wounds
• - surgical wounds
• - instrumentation
• Increased antibiotic use
• Increased immunosuppression.
• Over represented risk groups (Children, elderly,
  diabetics)

4
Reservoirs (source of organism)

• Exogenous - other patients
• - staff - carriers
• - normal flora
• - environment
• Endogenous - patients own normal flora
• Effect of hospitalisation on normal flora
• changes increased contact antibiotics

5
Transmission of Infection

• Direct transmission - patient to patient
• - staff to patient
• Indirect transmission
• Reservoir
• Intermediate
• Patient

Staff as mechanical vectors Fomites and
instruments Common source vehicles
6
Handwashing

• Australian paediatric ICU survey on clinician
  handwashing
• Only 3 washed before and after.
• Increased to 33 when informed about being
  observed.
• Incraesed to 70 when non washers were
  identified to their peers.
• (Tibbles, Med Journal of Aus, 1996, vol 164, pp
  389)

7
Common source outbreak

• 5/31 cardiac surgery patients with infection with
  Serratia marcescens over 1 month. 1 death
• Nurse A and surgery early in week were determined
  to be risk factors.
• Nurse A, and all other staff and 600
  environmental swabs were all negative for the
  organism.
• Visited Nurse As home and did cultures.
• Positive culture (200 000 / gram) in hand cream
• Batch samples of cream were negative.
• She only used cream on Sundays!

8
Cross contamination via fomites

• 1994 Australian Survey
• 38 - 54 of hospitals were re-using items
  designed for single use.
• In 60 of cases, the items were INADEQUATELY
  sterilized between uses.
• 13/14 most commonly re-used items were impossible
  to adequately sterilize because of their nature.

9
Hospital Microorganisms

• 25 - 30 of patients receive some antibiotic
  therapy.
• This provides the selective pressure to increase
  the proportion of antibiotic resistant organisms.

Inherently R organisms e.g. Pseudomonas
S organism become R
Resistant bacteria are NOT more virulent, but
they have increased opportunity to cause disease
and the outcome may be worse.
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
Prevention of Nosocomial
15
Prevention of Nosocomial Infection.

• Prevention is NOT possible, but reduction /
  minimisation is.
• Cannot reduce microbial burden (hospital or
  patient).
• Cannot reduce host susceptibility.
• Can minimise exposure and interupt transmission
• Isolation of patient (forward or reverse)
• Handwashing.