Healthcare-Associated Infections - Nosocomial Infections


Indications for Testing

  • Clinical deterioration and/or new onset fever in a hospitalized patient

Laboratory Testing

  • Initial testing – CBC, urine, and blood culture
  • Specific site testing based on clinical situation – refer to CDC/NHSN Surveillance Definitions for Specific Types of Infections publication
    • Use of CDC definitions may be helpful in defining patient healthcare-associated infections (HAI)
  • Bacterial strain characterization – aids in identification of outbreak source to optimize infection control and prevention efforts

Imaging Studies

  • Chest x-ray – rule out pneumonia
  • Further imaging may be necessary based on clinical presentation

Clinical Background

Healthcare-associated infections (HAI) develop as a result of a stay in a hospital or healthcare facility and are often caused by organisms resistant to standard antibiotic/antifungal therapies. Outbreaks in hospitals and extended-care facilities may spread to the general community and can cause substantial morbidity and mortality.


  • Prevalence – 5-10% of patients admitted to U.S. hospitals will develop HAI (CDC, 2014)
  • Incidence – >700,000 cases annually (CDC, 2014)
  • Transmission – acquisition of HAI may occur from poor hand hygiene, prosthetic devices, inadequate decontamination of fomites (eg, doorknobs, handrails)
  • Most common HAI-associated organisms (CDC, 2014)

    Most Common HAI-Associated Organisms (CDC, 2014)


    Most Frequently Associated HAIs

    Occurrence as Infection in Community Dwellers

    Drug Resistance

    HAI-Susceptible Populations

    Acinetobacter spp

    Multiple sites, including

    • Ventilator-associated pneumonia (VAP)
    • Bloodstream
    • Surgical site


    Multi drug resistant

    Severe illness

    Burkholderia cepacia



    Often drug resistant

    Chronic lung disease

    Cystic fibrosis

    Immunocompromised state

    Carbapenem-resistant Enterobacteriaceae (eg, Klebsiella spp., E. coli)

    Multiple sites, including

    • VAP
    • Urinary catheter
    • Bloodstream


    Resistance to carbapenem and multiple other agents

    Nursing home residence

    Prolonged or multiple courses of antibiotics

    Clostridium difficile

    Gastrointestinal illness

    >50% are community dwellers who have recent inpatient status as risk factor

    May be drug resistant

    • Virulent strain –BI/NAP1/027

    Exposure to antibiotics

    Previous recent hospitalization (<30 days)

    Clostridium sordellii

    Multiple sites, including

    • Endocarditis
    • Arthritis
    • Myonecrosis
    • Peritonitis
    • Pneumonia


    Resistance to cephalothin and aminoglycosides reported


    Gram-negative bacteria (Klebsiella spp., Pseudomonas aeruginosa, E. coli)

    Multiple sites, including

    • UTIs
    • Bloodstream
    • Surgical site
    • VAP

    May occur (eg, UTIs); causal organisms are common community-acquired pathogens (eg, E. coli)

    May be multi drug resistant


    Nursing home residence

    Mycobacterium abscessus

    Soft tissue and skin infections

    Lung infections in patients with chronic lung disease


    Prolonged therapy required

    First-line TB drugs are not effective

    • Surgical intervention may be warranted

    Immunocompromised state

    Chronic lung disease





    Nursing home residence (elderly)

    Daycare (children)

    Staphylococcus aureus (methicillin-resistant [MRSA] and -sensitive)

    Multiple sites, including

    • VAP
    • Bloodstream
    • Osteomyelitis
    • Endocarditis

    Up to 30% in community dwellers (MRSA)

    Most common presentation is skin and soft-tissue infections

    Multi drug resistant, including methicillin (MRSA) and rarely vancomycin

    Nursing home residence

    Diabetes mellitus

    Chronic kidney disease

    Indwelling catheter

    Vancomycin-resistant enterococci (VRE)

    Multiple sites, including

    • Urinary catheters
    • Bloodstream
    • Surgical sites


    Multi drug resistant, including vancomycin

    Recent treatment with vancomycin

    Previous colonization with VRE

    Indwelling catheter

Distribution of Infections (CDC, 2014)

  • Adults
    • Urinary tract – 13%
    • Surgical site – 22%
    • Lung – 22%
    • Bloodstream – 10%
    • Gastrointestinal illness – 17%
    • Other – 16%
  • Children
    • Higher rates of bloodstream, viral, and lower respiratory tract infections than adults
    • Lower rates of catheter-related urinary tract infections, ventilator-associated pneumonia, and surgical-site infections

Clinical Presentation

  • Nonspecific
    • Worsening clinical condition with no distinct symptoms; fever or hypothermia
  • Site-specific  symptoms
    • Pneumonia – new infiltrates on chest x-ray; worsening oxygenation
    • Meningitis – altered consciousness, irritability, seizures
    • Site infections – purulent drainage, site pain


Indications for Laboratory Testing

  • Tests generally appear in the order most useful for common clinical situations
  • Click on number for test-specific information in the ARUP Laboratory Test Directory
Test Name and Number Recommended Use Limitations Follow Up
CBC with Platelet Count 0040002
Method: Automated Cell Count

Assess for presence of leukocytosis, leukopenia or differential shift

Findings are not specific for a particular organism

Urine Culture 0060131
Method: Culture/Identification

Determine source of infection and causative organism(s)

Gram stain is performed by request only

Blood Culture 0060102
Method: Continuous Monitoring Blood Culture/Identification

Determine source of infection and causative organism(s)

Testing is limited to the University of Utah Health Sciences Center only

Bronchoscopy Culture and Gram Stain 0060700
Method: Quantitative Culture/Identification

Identify causative organism in presumed pneumonia

Includes gram stain testing

Wound Culture and Gram Stain 0060132
Method: Stain/Culture/Identification

Determine source of infection and causative organism(s)

Includes gram stain testing

Anaerobe culture is NOT included with this order

Bacterial Strain Characterization by Pulsed-Field Gel Electrophoresis 0060182
Method: Pulsed-Field Gel Electrophoresis

Determine relatedness of organisms suspected to be part of an outbreak

Distinguish reinfection from relapse

Carbapenem-Resistant Organism Culture 2011418
Method: Culture/Identification

Use in screening patients for carbapenem-resistant organisms as recommended by CDC (see Guidance for control of Carbapenem-resistant Enterobacteriaceae [2012])