• heat (moist or dry)- monitor with spore test kits
• filtration
  • air- high efficiency particulate air filters (HEPA)
  • liquids
• gas: ethylene oxide, formaldehyde
• radiation: UV, ionizing
• chemicals: glutaraldehyde

• efficacy- approach sterilization in effectiveness
• use- instruments designed for invasive procedures that cannot withstand heat sterilization
  • ex: instruments with plastic components
• importance- instruments need to be cleaned first to remove organic matter which may inactivate disinfectants

  • examples

    • moist heat
    • glutaraldehyde
    • chlorine- irrev. oxidation of SH group

• most resistant- bacterial spores
  1. mycobact.
  2. nonlipid or small viruses
  3. lipid enveloped, medium sized viruses
  4. bacteria
• least resistent- fungi

• used- clean instruments or surfaces where contamination with resilient organisms or spores is unlikely
  • ex: flexible fiberoptic endoscopes, laryngoscopes, vaginal specule
• agents used
  • alcohols
  • phenolic compounds
  • chlorhexadene
  • iodophores (iodine + carrier)
    • povidone iodine: iodine + polyvinylpyrrolidone

• used to treat noncritical instruments and devices or environmental surfaces
  • examples: bp cuffs, EKG electrodes, stethoscopes
• agents- quaternary ammonium compounds

• selected for safety and efficacy
• must clean the skin prior to application because organic matter may decrease effectiveness
• examples
  • clean skin with alcohol swab (rapidly cidal with no residual activity)
  • chlorhexidine
  • iodophore

• MRSA
• VRE
• resistant gram negative bacilli
• Candida

• UTI

• severity of underlying disease
• immunosuppresion
• invasive medical interventions

• airborn (ex: TB, varicella, Aspergillus)
• contact (ex: S aureus, enterococci, gram negative bacilli)
• common vehicle (ex: food contamination leading to outbreak, Salmonella, hep A)
  • usually found in hospitals in developing countries

• occurs in immunocompromised hosts
  • primarily as a pulmonary infection
  • acquired by inhalation of fungal spores
  • examples
    • granulocytopenia, bone marrow transplants
• associated with hospital construction, both internal and external
• prevention
  • seal off construction site
  • negative airflow
  • air filtration

• chromosomal mecA gene produce product that alters PBP 2' or 2a in cell wall
• this leads to low affinity for all beta lactam antibiotics

• previous positive MRSA culture
• history of hospitalization, surgery, dialysis, or residence in long term care facility in last year
• indwelling catheter/percutaneous device

• community acquired
• hospital acquired (at least 48 hrs after admission)
• heathcare associated community onset

• prolonged hospitalization
• prolonged antimicrobial therapy
• location in ICU
• proximity to known MRSA case

• persistent colonization up to four years in the nares
• contamination on environmental surface can be as high as 30% (ex: bed rails, table, bp cuffs)

• increase in prevalance related to frequency of invasive procedures, prosthetic devices
• extracellular glycocalyx (slime) allow it to attach to plastic and metal surfaces

Increasing incidence of methicillin resistance

• clinical manifestation
  • UTI
  • bacteremia
• mechanism of resistance
  • via genes that reside on plasmids or chromosome
  • alteration in PBP's
• higher incidence in larger hospitals, teaching hospitals, ICU's
• same mortality as V sensitive enterococcal infection

• age
• prolonged hospitalization
• prolonged antimicrobial therapy (w/beta lactams, vancomycin)
• location in ICU
• proximity to VRE

• persistant colonization of GI tract
• contamination of environmental surfaces
  • due to slime capsule (EC glycocalyx)

• examples: Pseudomonas, Klebsiella (worry most about these two), Enterobacter, E coli, Serratia, Acinetobacter
• selective pressure from high antibiotic usage caused their emergence
• resistant to extended spectrum penicillins, cephalosporins, aminoglycosides, quinolones
• colonize multiple body sites
  • GI
  • skin
  • pharynx

• 10-15% of all hospital acquired blood stream infections
• 25% of UTI's in ICU
• species: C. albicans (found most in both neutropenic and non neutropenic hosts)
• increased length of stay: 10-30 days
• attributable mortality: 20-50%
• associated with those on TPN

• malignancy
• neutropenia
• transplantation
• surgery
• ICU
• CVC
• TPN (nutrition: lipid component predispose to infection)
• antibiotics
• immunosuppression

• type of catheter: greater risk with plastic than steel
  • multiple lumber greater risk than single lumen
• location: central greater risk than peripheral
• duration of placement: more than 72 hrs
• emergency placement greater than elective
• skill of venipuncturists

• local inflam. or phlebitis at catheter insertion site
• bacteremia caused by associated organism: MRSA, coagulase neg. Staph, VRE, Candida
• Candida endophthalmitis in patients receiving TPN

• make rollplate techniques
• Process
  • catherter tip or intracutaneous segment is rolled on agar plate
  • colonies are counted
• more than 15 colonies correlates with colonization and potential sources of bacteria

• used for long term IV therapy
• adv.- much lower rate of infection
• Mech. of preventing infection
  • dacron cuff incites inflam. response/fibrosis at insertion site
  • prevents bacteria from migrating along external catheter surface
• location of potential infection: exit site, tunnel, tip
  • tunnel infection always requires catheter removal
• risks- septic thrombophlebitis/PE

• meticulous insertion technique
• minimize duration of catheterization
• use single vs. multiple lumen catheters
• antibiotic impregnated catheter

• gram negative bacilli
• VRE
• Candida

• external (most common)
  • colonization of urethral meatus
  • mov't of bacteria along/outside of the fluid layer of external catheter surface
• internal
  • colonization of urine in bag
  • ascend through catheter lumen

• avoid catheterization
  • intermittent (in and out) catheterization
  • minimize duration of catheterization
• dependent drainage
• aseptic insertion technique
• closed system
• silver coated catheter

• usually endogenous organisms (Klebsiella, Enterobacter)
• other pateints
• visitors
• envir. sources

Ventilator associated pneumonias happen 48-72 hrs post endotracheal intubation

• severity of underlying disease
• duration of hospitalization
• prior or concurrent use of antibiotics
• advanced age
• intubation
• major surgery
• achlorhydria

• handwashing, gloves
• closed ventilator circuits
• semi recumbent positioning (avoid large gastric volumes)
• avoid prolonged nasal intubation (prevent sinusitis)
• possibly maintain gastric acidity

• can become clinically apparent after discharge
• causative agents- skin organisms that go into wound
  • S aureus
  • gram negative bacilli
• risk factors
  • underlying disease
  • skill of operator
  • duration of operative procedure
• decrease risk by appropriately timed pre op antibiotics

• purpose- protect patient and self
• standard precaution- routinely consider all body fluids and moist surfaces as potentially infectious
• types
  • airborne precautions
  • droplet precautions
  • contact precautions

• private room w/negative pressure (air stays in room)
• need 10 air exchanges per hour (clear air in the room)
• particulate respirators for staff
• prevention of:
  • TB
  • varicella
  • influenza?

• agents protecting from: group strep A, influenza? (anything with resp. secretions via close personal contact)
• they need a private room
• particulate respirator or regular mask (no need for negative pressure or increased air exchange)

• transmitted via hands of personal, intimate surfaces
• types
  • handwashing
  • gloves with patient contact
  • private room
• protect from:
  • MRSA
  • VRE
  • highly resistant gram neg rods
  • influenza

• noticed two obstectric wards where one ward had a lot of mortality (ob/gyns and students) with puerpural sepsis and one had lower mortality (midwives)
• noticed that:
  • lower mortality when students on vacation
  • pathologist who cut himself during autopsy developed similar illness (puerpural sepsis, caused by group A strep)

Solution: hand hygiene in autopsy room prevented transmission of organism to delivery suite.