Healthcare-associated Infections

Technical Information — Multi-Site Resistant Gram-Negative Bacilli Surveillance Initiative (MuGSI)

Background

The Multi-Site Resistant Gram-Negative Bacilli Surveillance Initiative or MuGSI is a part of the CDC’s Emerging Infections Program (EIP) Healthcare-Associated Infections Community Interface (HAIC) activity. Through MuGSI, CDC is conducting active population- and laboratory-based surveillance in a defined surveillance catchment for six carbapenem-resistant organisms which include Escherichia coli, Enterobacter cloacae, Enterobacter aerogenes, Klebsiella pneumoniae, Klebsiella oxytoca, and Acinetobacter baumannii.

Surveillance Objectives

To evaluate the population-based incidence of carbapenem-nonsusceptibility among five common strains of Enterobacteriaceae and Acinetobacter baumannii, and describe how the incidence changes over time
To better characterize carbapenem-nonsusceptible strains in sites submitting data in order to inform prevention efforts
To describe known resistance mechanisms among a subset of carbapenem-nonsusceptible Enterobacteriaceae

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Methods

Surveillance Population

Surveillance for these MuGSI organisms is conducted in five EIP sites. The table below illustrates the population under surveillance for each EIP sites as of May 2012

**MuGSI Surveillance Population**
State	Population
CO	2,433,772 (5 county Denver area)
GA	3,893,877 (8 County Atlanta area)
MD	1,880,209 (3 county Baltimore area and Baltimore City)
MN	1,662,490 (2 metro Twin Cities counties)
OR	1,650,316 (3 county Portland area)
Total	11,520,664

Case Definition
- Case Patient: Cases will be defined as carbapenem-nonsusceptible (intermediate or resistant) and extended-spectrum cephalosporin resistant E. coli, Enterobacter aerogenes, Enterobacter cloacae, Klebsiella pneumoniae and Klebsiella oxytoca, or carbapenem-nonsusceptible (intermediate or resistant) Acinetobacter baumannii complex isolated from normally sterile sites or urine from residents of the surveillance area.
Case Classification:
- Case-patients infections will be characterized as hospital-onset, healthcare-associated community onset, or community-associated. A case will be classified as hospital onset if the symptoms associated with the carbapenem-nonsusceptible isolate had onset greater than 3 calendar days after hospital admission (admit = day 1).
  A case will be classified as healthcare-associated community-onset if the symptoms-associated with the carbapenem-nonsusceptible isolate had onset within the first 3 days after hospital admission and one or more of the following is true based on information from the medical record:

a history of hospitalization, surgery, dialysis, or residence in a long-term care facility in the year prior to initial culture; and/or
a central vascular catheter or urinary catheter in place ≤ 2 calendar days prior to the collection of the index culture

If none of the above criteria are met, the case will be classified as community-associated according to medical records.

Case Ascertainment:
- Cases will be identified through clinical microbiology laboratory data. Normally sterile sites include: blood, cerebrospinal fluid (CSF), pleural fluid, pericardial fluid, peritoneal fluid, joint/synovial fluid, bone, internal body site (lymph node, brain, heart, liver spleen, vitreous fluid, kidney, pancreas or ovary), muscle or other normally sterile site.
Laboratory Characterization:
- As part of this surveillance project, a small subset of isolates will be collected for further testing and characterization at CDC. Carbapenem-nonsusceptible Enterobacteriaceae (E. coli, E. cloacae, E. aerogenes, K. pneumoniae and K. oxytoca) isolated from a normally sterile site will be eligible for collection.
- Laboratory testing includes strain typing and isolate characterization.
Laboratory Audits
- To ensure complete case ascertainment, audits of allclinical laboratories that routinely process specimens from residents of a surveillance area, both within the surveillance area and those outside the catchment area, are conducted yearly. The primary data source at every reporting site (e.g. laboratory log slips/log book, computer-generated electronic printouts) is reviewed and compared to the list of cases that were reported to the surveillance personnel. Case report forms are completed on all newly identified cases.
- Due to the controversy and recent recommended changes in the carbapenem susceptibility breakpoints for Enterobacteriaceae, sites conduct at least yearly reviews of the breakpoints being used at participating facilities. Information collected included the breakpoints that are currently being used to define susceptibility to carbapenems and the date changes were made in the breakpoints being applied to define susceptibility.