Nosocomial Infections: Infection Control and Hospital Epidemiology

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Nosocomial Infections Infection Control and
Hospital Epidemiology

• Tobi B. Karchmer, MD, MS

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What is Hospital Epidemiology?

• The study of events (infectious or
  non-infectious) which occur in hospitalized
  patients as a result of being hospitalized,
  having surgery or other surgical procedure, or of
  receiving a treatment.

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What defines a hospital?

• An institution which cares for and houses
  patients who are
• acutely ill.
• chronically ill.
• rehabilitating.
• An institution which provides
• surgical procedures.
• An institution which cares for patients
• in outpatient clinics or at home.

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How do we define nosocomial events?

• An event/infection which
• develops 48-72 hours after hospitalization.
• is not incubating on admission.
• is related to a procedure/treatment performed in
  a hospital or health care facility.

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How do we study nosocomial events?

• Observational studies - surveillance
• Outbreak investigation
• Communicable disease exposures
• Risk factor assessment
• Outcome assessment

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What are the goals of hospital epidemiology
programs?

• Determine the rates of nosocomial events
• Understand the epidemiology of nosocomial
  infections and events
• Determine strategies to control and prevent
  nosocomial events

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Nosocomial Infections in the United States

• Affect gt 2 million people annually
• 5-10 of all pts admitted to hospitals
• Contribute to 3 of deaths in hospitalized
  patients
• Cause 1 of deaths
• Contribute or cause 88,000 deaths
• Cost over 5-10 billion

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Why Are Hospitalized Patients at High Risk for
Infection?

• Underlying illnesses
• Cross-transmission of hospital flora
• poorly designed facilities
• low nurse to patient ratios / other process of
  care or infrastructure issues
• human behaviors (such as, poor compliance with
  hand hygiene)

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Why Are Hospitalized Patients at High Risk for
Infection?

• Interventions
• surgery
• invasive devices
• urinary catheter
• vascular catheters
• ventilators
• antibiotic use
• Infected HCWs or contaminated equipment

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Nosocomial Infections

• Majority (95) endemic
• Definitions-infection vs. colonization
• clinical symptoms and signs
• laboratory results
• Categorized by
• body site
• pathogen

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Distribution of Major Types of Nosocomial
Infections
Microbiol Rev 19936428
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Impact of Nosocomial Infections
MMWR 199241783, Pittet, JAMA 19942711298,
Classen, Univ of Utah, 1993 (thesis)
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Urinary Tract Infection

• Foley catheter
• 80-90
• Genitourinary manipulations
• 5-10
• With a Foley bacteriuria is inevitable given
  sufficient time

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Risk Factors for Nosocomial UTI

• Duration of catheterization1-4
• Absence of systemic antibiotics1-6
• Female gender2,3,5,6
• Older age3,5
• Catheter care violations2,5
• 1 Shapiro, Infect Control 19845525. 2 Platt,
  Am J Epidemiol 1986124977. 3 Riley, Am J Med
  199598349. 4 van der Wall, Lancet
  1992339946. 5 Garibaldi, NEJM 1974291215.
  6 Johnson, J Infect Dis 19901621145.

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Infection vs Duration of Catheterization
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Nosocomial InfectionsUTI - Interventions

• Effective
• Closed drainage
• Decreased duration
• Intermittent cath.
• Decontamination of collection devices
• Urine bag in proper position
• Silver coating
• Handwashing

• Ineffective
• Antibacterial lubricants
• Meatal cleansing
• Condom catheter
• Antibiotic irrigation
• Disinfecting the bag with H202, iodine, etc.

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Risk of Infection Associated With IO
Catherization
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Nosocomial Pneumonia Risk Factors

• Surgery - thoracic and abdominal
• Age
• Chronic lung disease
• Depressed level of consciousness
• MECHANICAL VENTILATION

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Risk of Pneumonia vs Duration of Intubation
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Nosocomial InfectionsLRI - Modifiable Risk
Factors

• Strong evidence
• Semirecumbent
• Noninvasive ventilation
• Continuous lateral rotation
• Subglottic suctioning
• Weekly circuit changes

• Some evidence
• Avoid oversedation
• Avoid paralytics
• Closed suctioning
• Orotracheal intubation
• Maintain adequate cuff pressures
• Avoid H2 antagonists

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Nosocomial InfectionsPneumonia - Diagnosis

• In intubated patients, dont culture unless you
  suspect pneumonia, you will grow something
• Do a quantitative culture when possible -
  suctioned or BAL, they are more accurate gt 10K
  suggests infection
• Do a gram stain with each culture to look for
  associated purulence

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Surgical Site InfectionsRisk Factors

• Intrinsic
• Age
• Malnutrition
• Severity of illness (ASA score)
• Underlying diseases
• Diabetes
• Obesity
• Cancer /immunosuppression
• Trauma
• Loss of skin integrity

• Extrinsic / Modifiable
• Remote infections
• Prophylactic antibiotics
• Surgeon- related
• Experience
• Length of operation
• Surgical technique
• Prolonged preoperative stay
• Preoperative shave
• Abdominal drains

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Bloodstream InfectionsRisk Factors

• Extrinsic
• intravenous catheters
• duration of catheterization
• Intrinsic
• age lt 1, gt 60 y.o.
• immunosuppressive chemotherapy
• loss of skin integrity
• severity of underlying illness

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Time Course of Initial Colonization of Triple
Lumen Catheters in ICU Pts
Sherertz, J Clin Microbiol 199735541
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Nosocomial Catheter-related BSI - Prevention

• Effective Measures
• Education
• Chlorhexidine prep
• Maximum sterile barriers
• Catheter coatings - AgSD/Ch, Mino/Rif
• Antibiotic ointment - hemodialysis cath. only

• Non-effective
• Prophylactic antibiotics
• Scheduled changing of catheters
• Tunneling catheters

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Immunizations
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Rational for Vaccination of HCWs

• Protect the worker
• Limit the spread of infectious diseases to
  patients, visitors and other HCWs
• Reduce HCW sick days
• Limit potential for outbreaks

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Influenza Vaccine for HCWs Decreases Patient
Mortality!!

• Winter 1994-5, 1059 pts in 12 geriatric hospitals
• 6 hospitals routinely vaccinated all pts, 6
  hospitals only vaccinated pts when requested
• HCWs stratified based on hospital policy
• vaccination of HCWs decreased pt mortality 17
  to 10 (OR0.56, p0.0009)
• vaccination of patients did not affect mortality
  (OR1.15, 95CI 0.81-1.64)
• Potter et al., JID 19971751

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Side Effects and Influenza Vaccination

• 849 HCWs randomized, double-blind, placebo
  controlled trial
• assessed for fever, malaise, fatigue, myalgia or
  headache - 7 days after immunization
• independent predictors of side effects female
  gender, age lt40 years old, coincidental upper
  respiratory infection
• vaccine was not associated with side effects
• Nichol et al., Arch Intern Med 19961561546

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Take Home Lessons

• All hospitalized patients are at risk for
  developing nosocomial infections
• Invasive devices substantially increase the risk
  (catheters, ventilators, Foleys)
• NI can be minimized by proper technique on
  insertion and proper care of invasive devices

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Take Home Lessons

• All HCWs should have a yearly influenza vaccine