Infection Control -Lecture

Infection Control -Lecture

1. Controlling the spread of infectious disease is especially important in places such as hospitals, dental surgeries and nursing homes. Patients at these place are particularly vunerable to hospital acquired infections

   • Hospital acquired infections (HAI's) are nosocomial infections. Microorganisms can grow commensally on the human body or in the environment, these can then be easily transmitted

2. Sources of HAI's

   • Oppurtunistic pathogens from the patients own flora
   • Transmission from other patients or clinical staff
   • Environment of the hospital and surfaces such as handles and rails
   • Medical instruments such as endoscopes
   • Air can transmitt bacteria, air conditioning can help circulate bacteria (such as legonella)
   • Water borne pathogens such as norovirus (taps and sinks)
   • Food can easily be contaminated as it is in close proximity to procedures, also issues with large scale catering
   • Needlestick injuries and other wounds
   • Aerosols, blood, splatter and skin fragments

3. Common/ high priority examples of HAI's

   • Staphylococci (natural commensal versitile organisms) such as MRSA
   • Clostridium diffcile common in elderly patients treatment with antibiotics
   • Acinetobacter baumanii especially in intensive care units
   • Gram negative bacteria with potential for serious infections in individiuals with a supressed immune system
     • Klebsiella spp
     • Peudomonas spp
     • Stenotrophomonas maltophilia
   • Norovirus - debilitation
   • Serious Viral infections
     • HIV/AIDS
     • Hepatitis B and C

4. Attempting to understand HAI's

   • Determing difference between sporadic cases (individual unlinked cases) and actual outbreaks (number of linked cases)
   • Understand drug resistance owing to selection pressue
     • Use of antibiotics needs to be carefully controlled
     • mecA is the gene carrying MRSA resistance phenotype
     • Vancomycin resistance
     • Extended-spectrum beta-lactamases these are found in HAI's but not in nature (hospital provides selection pressues)

5. Combatting HAI's

   • To minimize the spread it is vital to attempt to interfere with route of transmission
   • Hand Hygiene
     • Alcohol hand gel is a convienent washing system rather than soap
     • Still psycholoigcal issues of getting people to wash hands in line with procedures
   • Cleanliness of environment eg: beds
   • Screening of patients (MRSA)
   • Isolation barriers
   • Operating theatres
     • Patients with open wounds are particularly suseptible to infections (hip and knee replacements)
     • 'Foreign bodies' are especially prone to infection eg: proesthese (staph epidermidis is an oppurtunistic pathogen noted for infecting these). The immune system not evolved at regnosing this
     • Patients skin is disinfected (iodine and alcohol) before surgery to remove any skin bacteria
     • Surgeons scrub up and use remove any excess skin before entering. Some have air extraction in suit to prevent skin peices falling
     • Laminar air flow - HEPA filtered air keeps air clean