3. Healthcare-associated Infections

  1. healthcare-associated infections
    • infections acquired while in the healthcare setting with a lack of evidence that the infection was present or incubating at the time of entry into the healthcare setting
    • also known as nosocomial infections
    • 1/20 patients hospitalized contract
  2. Semmelweis
    • noticed mothers giving birth in ward were less likely to develop puerperal fever if delivered by nurses instead of med students
    • instituted hand washing measures and brought down level of fever
  3. Lister
    • pioneer of antiseptic surgery
    • used carbolic acid for wounds and to sterilize surgical equipment
    • had surgeons wear masks and gloves to prevent infection
  4. types of HAI
    • bloodstream infections - central line-associated bloodstream infection
    • urinary tract infections - catheter-associated urinary tract infection
    • pneumonia - ventilator-associated pneumonia
    • surgical site infection
    • clostridium difficile infection
  5. most common organisms in HAI
    • staphylococcus species
    • enterococcus species
    • candida species
    • escheriscia coli
    • pseudomonas aeruginosa
    • klebsiella pneumoniae
    • enterobacter species
    • acinetobacter baunmannii
    • clostridium difficile
  6. characteristics of nosocomial pathogens
    • survive for long periods on environmental surfaces
    • remain virulent after environmental exposure
    • ability to colonize patients
    • transiently colonize hands of HCW and be transmitted
    • small inoculating dose
    • resistance to disinfectants
  7. endogenous reservoir
    self-infection from another site in the body
  8. exogenous reservoir
    • from another person
    • from the environment
    • IV fluids
  9. hands
    • 20-40% of HAI from infection via hands
    • can result from = direct patient contact, indirectly touching contaminated surfaces
    • patients can also become colonized by direct contact with a surface
  10. transmission
    • direct contact: hands, fomites
    • airborne: droplets, droplet nuclei
  11. risk factors for HAI
    • hospitalization for more than 2 days
    • residence in long-term care facility
    • home infusion therapy
    • long-term dialysis within 30 days
    • home wound care
    • family member with multidrug-resistant pathogen
  12. risk factors for HAI with drug-resistant bacteria
    • antimicrobial therapy in preceding 90 days
    • current hospitalization >5 days
    • high frequency of antibiotic resistances in the community
    • immunosuppression
  13. CLABSI
    • infections are so common considered a routine complication
    • ~>50% are preventable
  14. pneumonia
    • one of the most common HAI in US
    • risk factors - extremes of age, underlying disease, immunosuppression, cardiopulmonary disease
    • those with ventilator are at highest risk
  15. surgical site infections
    • 14-16% of HAI
    • increasing number caused by antimicrobial resistant pathogens
    • sometimes skin only, others involve organs and are more serious
  16. urinary tract infections
    • most common HAI
    • infection from catheterization most common
    • many preventable with proper management of catheter
  17. prevention of HAI
    • only use catheters when needed
    • follow antiseptic technique when inserting catheter and central lines, performing surgery
    • disinfect equipment and hospital surfaces
    • surveillance
    • wash hands
  18. systemic changes
    • infection control can be cost effective
    • insure surveillance uses are valid
    • improve design of invasive devices
    • forestalling the post-antibiotic era
    • newer microbiologic methods
    • successful collaboration
  19. government
    • quality report to congress
    • medicare payments to hospitals reduced for preventable readmissions and for certain infections that can usually be prevented with good care
    • american recovery and reinvestment act included money to assist states
  20. C. difficile infections
    • produces spores - can survive for many years in an aerobic environment
    • leading cause of nosocomial-acquired diarrhea - usually after completing antibiotics
    • reservoir in humans
    • transmission with hands, fomites
    • toxin mediated
  21. three-hit hypothesis of C.dfficile
    • antibiotics changes normal flora
    • colonization with virulent strain
    • host predisposition
  22. diagnosis of C. difficile
    • culture - often not performed
    • toxin assay - poor sensitivity and specificity
    • cepheid Xpert - automated machine performs PCR test to detect organism
  23. clinical symptoms of C. difficile
    • diarrhea
    • colitis - diarrhea, blood and pus in stool
    • toxic megacolon - paralysis of peristaltic movement, feces can consolidate in hard masses in colon
  24. C. difficile treatment
    initial - discontinue antibiotics, supportive care (hydration and electrolyte replacement), avoid anti-diarrheals, antibiotics

    relapse - antibiotics, probiotics, bile sequestration, passive immunization
  25. C. difficile prevention
    • contact precautions when diarrhea present
    • environmental disinfection
    • timely diagnosis and isolation
    • decrease unnecessary antibiotic use
    • vaccine
Card Set
3. Healthcare-associated Infections
public health microbiology midterm 2 lecture 3