Microbiology & Immunology - Nosocomial (Hospital-Acquired) Infections

Infection control team

- Infection Control Nurse or Practitioner - Infection Control Officer/Physician - Infection Control Laboratory - gathers info/analyzes data - elaborates policies for Infection Control Committee - watches implementation of such policies - participates in education programs - reviews and updates periodically the techniques - elaborates a "Manual of Procedures in Infection Control" and keeps up to date

The Susceptible Host

- an individual infected with a microorganism carried from the source via one of the routes of transmission

Universal precautions and isolation procedures

- are aimed at preventing the spread of microorganisms to other patients (and HCP) from the source of infection 2 MEASURES: - universal precautions - isolation procedures applied to infected patients: they should be adapted to the mode of transmission of the infecting agent and to the seriousness of the infection DISEASE-SPECIFIC CATEGORY-SPECIFIC = degree of danger, route of transmission, similar isolation precautions

Measure: The Host

- asepsis (e.g. in surgery) - vaccination when possible - protective isolation (e.g. isolation of transplant patients)

Detection of the source is done by:

- daily review of admission for identification of patients with infections - daily review of microbiology reports followed by investigation of suspected cases - examination of patients' charts and discussion with ward personnel - special infection report forms filled by ward nurses or physicians - lists of prescribed antibiotics - examination of fever charts

Measure: The Source

- detection/identification of sources - isolation/precautions - treatment of infections - elimination of inanimate sources or pests

Non-preventable infections

- due to causes which escape all reasonable means of prevention e.g. infections in the immunodeficient, surgery in patients with a perforated organ (e.g. accidental/shotgun wounds involving the intestines), etc.

Preventable infections

- due to faulty medical or nursing techniques (e.g. breaches in aseptic procedures in surgery/catheterization, improper hand washing, etc)

Sources for hospital-acquired infections include:

- environment - person-2-person (endogenous vs. exogenous?) - food supply - air supply - fomites - vector - water supply

The Source

- environment in which microorganisms multiply and from where they can be disseminated - can be infected individual or inanimate environment (e.g. food, water reservoir) - endogenous: patients own flora, exogenous: outside patient

What is a nosocomial infection?

- infection acquired by a patient during hospitalization and having its origin in the hospital environment or in a medical procedure - 25% patients - most common = urinary tract, respiratory, wound, skin, soft tissue, septicaemia

Control over nosocomials

- interrupt chain of infection by: 1. rendering the source non-infectious or by preventing the microorganism from leaving the source 2. interfering with the dissemination of infectious agents through the different routes of transmission or 3. preventing the microorganisms from entering the host or rendering the host resistant to infection **** most efficient is identification and detection of source of infection

Interference with route of transmission

- interrupt the mechanisms of transmission so that microorganisms that might have escaped from the source are prevented from reach host - destroy deposited/air suspended organisms by disinfectants, sterilization, housekeeping, ventilation

Protecting the host by

- prevent microorganisms from reaching host e.g. barriers - immunizing patient when possible

Infection control in communities

- social and environmental factors - health education - food safety - vector control - immunization - chemoprophylaxis - outbreak investigations - national and internation agencies

Measure: The Route

- sterilization - disinfection - proper medical/nursing techniques - ventilation - adequate housekeeping procedures

The Route of Infection

- the way by which the infecting microorganisms leaving the source reach the host - direct contact - indirect through contaminated objects - water or food - air - vectors

The Chain of Infection

1. Source 2. Route of Infection 3. Host