Multi-site Gram-negative Surveillance Initiative (MuGSI)

Overview

As part of CDC's Emerging Infections Program (EIP) Healthcare-Associated Infections – Community Interface Activity (HAIC), the Multi-site Gram-negative Surveillance Initiative (MuGSI) conducts surveillance for carbapenem-resistant Enterobacterales (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), and extended-spectrum beta-lactamase producing Enterobacterales (ESBL-E). From August 2016 to July 2018, surveillance also included carbapenem-resistant Pseudomonas aeruginosa (CRPA) in some areas.

MuGSI aims to:

• Determine the incidence of these bacteria in selected areas in the United States.
• Measure trends of disease over time.
• Identify risk factors.
• Describe antimicrobial resistance mechanisms and strain types.

To collect this information, trained professionals conduct active population- and laboratory-based surveillance in six to 10 EIP sites.

Data from this tracking project will help scientists understand illness caused by these bacteria. These data will help shape strategies to contain and prevent their spread.

Explore the data

Annual reports

• 2021 Annual CRE Report
• 2021 Annual CRAB Report
• 2021 Annual ESBL-E Report
• 2020 Annual CRE Report
• 2020 Annual CRAB Report
• 2020 Annual ESBL-E Report
• 2019 Annual CRE Report
• 2019 Annual CRAB Report
• 2019 Annual ESBL-E Report
• 2018 Annual CRE Report
• 2018 Annual CRAB Report
• 2017 Annual CRE Report
• 2017 Annual CRAB Report
• 2016 Annual CRE Report
• 2016 Annual CRAB Report
• 2015 Annual CRE Report
• 2015 Annual CRAB Report
• 2014 Annual CRE Report
• 2014 Annual CRAB Report
• 2013 Annual CRE Report
• 2013 Annual CRAB Report
• 2012 Annual CRE Report
• 2012 Annual CRAB Report

Publications

• Duffy N, Li R, Czaja CA, et al. Trends in Incidence of Carbapenem-Resistant Enterobacterales in 7 US Sites, 2016─2020. Open Forum Infect Dis. 2023;10(12):ofad609. Published 2023 Dec 5. doi:10.1093/ofid/ofad609
• Bulens SN, Reses HE, Ansari UA, et al. Carbapenem-Resistant enterobacterales in individuals with and without health care risk factors -Emerging infections program, United States, 2012-2015. Am J Infect Control. 2023;51(1):70-77. doi:10.1016/j.ajic.2022.04.003
• Karlsson M, Lutgring JD, Ansari U, et al. Molecular Characterization of Carbapenem-Resistant Enterobacterales Collected in the United States. Microb Drug Resist. 2022;28(4):389-397. doi:10.1089/mdr.2021.0106
• Duffy N, Karlsson M, Reses HE, et al. Epidemiology of extended-spectrum β-lactamase-producing Enterobacterales in five US sites participating in the Emerging Infections Program, 2017. Infect Control Hosp Epidemiol. 2022;43(11):1586-1594. doi:10.1017/ice.2021.496
• Bulens SN, Yi SH, Walters MS, et al. Carbapenem-Nonsusceptible Acinetobacter baumannii, 8 US Metropolitan Areas, 2012-2015. Emerg Infect Dis. 2018;24(4):727-734. doi:10.3201/eid2404.171461

About the data

Methods

EIP sites conducting CRE and CRAB surveillance

*California started CRE surveillance in August 2017 and does not participate in CRAB surveillance

EIP sites conducting ESBL-E surveillance

Case definitions

A case is defined as any of the following bacteria isolated from a person living in the surveillance area from a specific source (Table 3):

• CRE:
  • Escherichia coli
  • Enterobacter cloacae complex species (i.e., E. asburiae, E. bugandensis, E. cancerogenus, E. cloacae, E. hormaechei, E. kobei and E. ludwigii)
  • Klebsiella species (i.e., K. aerogenes, K. oxytoca, K. pneumoniae and K. variicola)
• CRAB:
  • Acinetobacter baumannii complex (A. baumannii, A. baumannii complex, A. calcoaceticus-baumannii complex [including A. calcoaceticus])
• ESBL-E:
  • Escherichia coli
  • Klebsiella pneumoniae
  • Klebsiella oxytoca
  • Klebsiella variicola

Specimen source and case definition

^*Sterile sites include: blood, cerebrospinal fluid, 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, deep tissue or other normally sterile site.

^§Lower respiratory tract specimens include bronchoalveolar lavage, sputum, tracheal aspirate or other lower respiratory site.

¶Lower respiratory tract and wound cultures added for CRAB surveillance at selected EIP sites in 2021.

Phenotypic case definitions

The minimum inhibitory concentration (MIC) and zone diameter interpretive criteria produced by the local clinical laboratory's primary antibiotic testing methodology are used to identify cases.

For the following bacteria, resistance means:

• CRE: resistance to one or more carbapenems (i.e., doripenem, imipenem, meropenem or ertapenem).
• CRAB: resistance to one or more carbapenems (i.e., doripenem, imipenem or meropenem).
• ESBL-E: resistance to at least one extended-spectrum cephalosporin (i.e., ceftazidime, cefotaxime or ceftriaxone) and non-resistant (i.e., susceptible or intermediate) to all carbapenems tested. The exclusion of carbapenem-resistant isolates ensures lack of duplication with existing MuGSI CRE surveillance.

Case ascertainment

EIP staff identify cases based on their clinical laboratory's antibiotic susceptibility testing data. Most local clinical laboratories conduct antibiotic testing using an Automated Testing Instrument (ATI). Many clinical laboratories within the surveillance area identify the specimen results meeting the MuGSI case definitions from these ATI systems.

Incident case

The first case of each organism per patient in a 30-day period is considered an incident case.

If a new specimen meeting the case definition is collected more than 30 days after the patient's last incident case of the same organism, they are also considered an incident case.

A case report form is filled out for incident cases as described below.

Non-incident case

If a patient tests positive for the same organism within 30 days of the first positive specimen collection date, they are not considered a new incident case. Surveillance staff do not complete case report forms in these instances.

Case report forms

The process for completing case report forms may differ across EIP sites but primarily consists of trained surveillance epidemiologists reviewing patients' medical records to gather information such as:

• Patient demographic characteristics.
• Location of specimen collection.
• Types of infections associated with the positive specimen.
• Underlying medical conditions.
• Healthcare exposures.

Case report forms are completed for all incidence CRE and CRAB cases. Case report forms are completed for the first incident ESBL-E case per species per patient in a 365-day period and for all incident ESBL-E cases from normally sterile body sites.

Laboratory characterization

EIP staff collect and submit isolates of bacteria that meet CDC surveillance definitions. CDC then:

1. Characterizes antimicrobial resistance mechanisms such as phenotypic carbapenemase production, phenotypic ESBL production and the presence of antimicrobial resistance genes) associated with the bacteria under surveillance.
2. Evaluates antimicrobial susceptibility testing results using a reference method.
3. Characterizes the molecular epidemiology of selected gram-negative bacteria.
4. Contributes some isolates to the AR Isolate Bank.
5. Shares results with EIP sites.

Resources

Case report forms for EIP surveillance staff

• 2024 MuGSI (including CRE, ESBL-E, CRAB and Invasive Escherichia coli)

More information

• Antibiotic Prescribing and Use
• Be Antibiotics Aware
• World Health Organization Advisory Group on Integrated Surveillance of Antimicrobial Resistance
• Transatlantic Taskforce on Antimicrobial Resistance
• European Committee on Antimicrobial Susceptibility Testing
• Canadian Integrated Program for Antimicrobial Resistance Surveillance
• AHRQ CRE Control and Prevention Toolkit