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Investigative Guidelines for Multidrug-resistant Organisms

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Mandatory Outbreak Reporting

Acute care hospitals and long-term care facilities (LTCFs) are required to report to the local health authority under OAR 333-018-0000 any healthcare-associated infections by multidrug-resistant organisms which meet the following threshold: “any known or suspected common-source outbreaks; any uncommon illness of potential public health significance” (OAR 333-018-0015; ORS 433.004). Local health authorities are empowered to investigate such outbreaks under OAR 333-019-0000, ORS 433.006.

Carbapenem-resistant Enterobacteriaceae is a reportable disease (OAR 333-018-0015; ORS 433.004).

Local health authorities need to report healthcare-associated multidrug-resistant organism outbreaks to the state communicable disease epidemiology program at 971-673-1111 within 24 hours of receiving an outbreak report. Download Outbreak Investigation Guidelines pdf).

Basic Definitions

Download MDRO Definitions (pdf)

Healthcare-associated multi-drug resistant organisms of public health significance include:

Infection: Isolation of a MDRO from a patient specimen with symptoms of infection.

Colonization: Isolation of a MDRO from a patient specimen without symptoms of infection.

Acute care hospitals: Short- and long-term acute care hospitals (LTACHs).

Long-term care facilities: skilled nursing homes (SNFs), nursing homes (NH), assisted living (AL),residential care (RC).

MDRO outbreaks in healthcare facilities:

  • General definitions: an “unusual” number of patients or residents with MDRO clustered by time and place.
  • Working definition: two or more patients or residents in the same hospital unit or same LTCF with matching MDRO (genus, species) and onset dates within 6 months of each other.

Control Measures

Data Collection and Basic Descriptive Epidemiology


Educational Resources

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