Nosocomial Infections

Question 1

Define and explain the terms “nosocomial” and “iatrogenic.”

Answer 1

Nosocomial: new disorder associated with being treated in a hospital
o Most are bacterial
o Many = related to use of medical devices
o 50% = preventable

Iatrogenic: unfavorable response to a medical or surgical treatment, induced by treatment itself

Question 2

Discuss the common types of nosocomial infections, the source of these infections, and the most common groups of pathogens involved.

Answer 2

Common organisms:
o Hospital acquired MRSA (Methicillin resistant Staph aureus)
o Enterococcus = Increasingly resistant to antibiotics (especially vancomycin and ampicillin)
o Candida albicans

Sources of infection:
o	Animate environmental source (ex: hands of hospital worker)
o	Inanimate environmental source:
1) Airborne: 
•	Asperfillus fumigatus
•	Chicken pox
•	Tuberculosis
•	SARS
2) Water-borne
•	Legionella pneumophila
•	Pseudomonas species

Question 3

List the major sites of infection for acquiring a nosocomial infection.

Answer 3

o	UTI (40%)
o	Surgical wound (25%)
o	Lower respiratory (15%)
o	Bacteremia
o	Clostridium difficile antibiotic-associated colitis

Question 4

Explain risk factors for acquiring a nosocomial infection.

Answer 4

ICU/Trauma units
•	Higher rates of infections
•	More multiple-resistant organisms 
•	Higher rates of bacteremia 
•	Higher rates of occupational infections in ICU workers

Invasive devices
•	#1 cause of nosocomial infections
•	Endotracheal tubes → pneumonia 
•	Urinary catheter → UTI
•	Central line catheter → bacteremia 

Other:
• Understaffing (especially of ICU nurses)
• Overcrowding and clustering of patients
• Surgery
• Exposure to antibiotics
• Surveillance not being done in many hospitals

Question 5

Describe the methods available to reduce and prevent the incidence of nosocomial infections.

Answer 5

Strategies for Control of Antibiotic Resistance
o Reduce antibiotic pressure
o Improve nosocomial infection control measures

Prevention
o Restrict use of invasive devices
o Use aseptic technique (including skin disinfection)
o Hand hygiene: Studies show hand washing is done < 50% of the time; New formulations of handwashing solutions are now in place = have improved compliance
o Follow patient isolation procedures
o Use HEPA filters for transplant patients (especially bone marrow, heart, and lung)

Question 6

Explain the new paradigm for controlling these infections.

Answer 6

More effective hand hygiene
o Waterless alcohol gels (but not destroy C. difficile)
o Antibacterial soap and water for soiled hands
• If patient has diarrhea or known C. difficile infection

Preemptive use of barrier precautions on all high risk patients

Assume all patients are at high risk

Procedures to minimize device-related infections:
o Disinfecting skin with 2% chlorhexidine
o Daily chlorhexidine sponge baths
o Device modification (e.g., cuffed catheter to reduce aspiration; silver or antiseptic coated catheter to prevent biofilm formation; chlorhexidine-impregnated site dressing)
o Aseptic technique education on insertion of devices
o Remove device ASAP
o Follow-up care
o Team dedicated to device insertion

Procedures to minimize water-borne transmission:
o Treat hospital water supply to minimize Legionella colonization
o Copper-silver ionization is used at UW hospital.

Procedures to minimize surgical infections:
o Most surgical infections = due to patient’s own organisms → appropriately timed antibiotic prophylaxis (< 1-2 hours before surgery)
• Allows for adequate concentrations are in tissues
o Active perioperative hyperoxygenation during surgery
o Intensive insulin therapy of critically ill patients

Procedures to minimize air-borne infection
o HEPA = air filtration, especially for Aspergillus fumigatus

Procedures to minimize ventilator device infections
o Semi-recumbent positioning
o Circuit condensate removed by heat moisture exchanges
o Use noninvasive technology, if possible
o Wean off devices as soon as possible
o Oral care with chlorhexidine

Procedures to minimize sharps injuries:
o Always use safety devices; never re-cap needles.
o Proper disposal into biohazard containers.

Computer assisted anti-infective therapy
o Microbiology database linked with requirement to enter medication orders on hospital computer system

Active perioperative rewarming during surgery