Key points
- The Multi-site Gram-negative Surveillance Initiative (MuGSI) identifies trends, antimicrobial resistance mechanisms, and risk factors for infections with selected Gram-negative bacteria.
- Public health professionals and healthcare providers can use these data to combat antimicrobial resistance and improve patient safety.
Overview
As part of CDC's Emerging Infections Program (EIP) Healthcare-Associated Infections – Community Interface Activity (HAIC), MuGSI conducts surveillance for carbapenem-resistant Enterobacterales (CRE), carbapenem-resistant Acinetobacter baumannii (CRAB), extended-spectrum beta-lactamase producing Enterobacterales (ESBL-E) and invasive Escherichia coli (iEC).
Aims
- 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.
Process
Trained professionals conduct active population- and laboratory-based case finding in EIP sites and complete report forms for incident cases. CDC and EIP staff clean, analyze, and disseminate the data through annual reports and peer-reviewed publications.
Pupose
MuGSI data help scientists understand the illnesses these bacteria cause and shape strategies to contain and prevent their spread.
Highlights
- In 2022, the crude incidence rates of CRAB, CRE, and ESBL-E in EIP sites were 2.3, 6.4, and 172.3 cases per 100,000 persons, respectively.
- The incidence rates for CRAB, CRE, and ESBL-E increased with age. The incidence rate of CRAB was higher in males than females, whereas the incidence rates of CRE and ESBL-E were higher in females than males.
- Healthcare exposures were common among cases with CRAB or CRE, whereas half of the cases with ESBL-E did not have any known relevant healthcare exposures.123
Explore the data
CRAB
- 2022 Annual CRAB Report
- 2021 Annual CRAB Report
- 2020 Annual CRAB Report
- 2019 Annual CRAB Report
- 2018 Annual CRAB Report
- 2017 Annual CRAB Report
- 2016 Annual CRAB Report
- 2015 Annual CRAB Report
- 2014 Annual CRAB Report
- 2013 Annual CRAB Report
- 2012 Annual CRAB Report
CRE
- 2022 Annual CRE Report
- 2021 Annual CRE Report
- 2020 Annual CRE Report
- 2019 Annual CRE Report
- 2018 Annual CRE Report
- 2017 Annual CRE Report
- 2016 Annual CRE Report
- 2015 Annual CRE Report
- 2014 Annual CRE Report
- 2013 Annual CRE Report
- 2012 Annual CRE Report
ESBL
- Grome HN, Grass JE, Duffy N, et al. Carbapenem-Resistant and Extended-Spectrum β-Lactamaase-Producing Enterobacterales in Children, United States, 2016-2020. Emerg Infect Dis. 2024;30(6):1104-1114. doi: 10.3201/eid3006.231734.
- 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
CRE and CRAB
| EIP site | Area under surveillance for CRE and CRAB |
|---|---|
| California* | Alameda, Contra Costa and San Francisco |
| Colorado | Adams, Arapahoe, Denver, Douglas and Jefferson |
| Connecticut | All planning regions |
| Georgia | Clayton, Cobb, Dekalb, Douglas, Fulton, Gwinnett, Newton and Rockdale |
| Maryland | Baltimore, Baltimore City, Carroll and Howard |
| Minnesota | Hennepin and Ramsey |
| New Mexico | Bernalillo |
| New York | Monroe |
| Oregon | Clackamas, Multnomah and Washington |
| Tennessee | Cheatham, Davidson, Dickson, Robertson, Rutherford, Sumner, Williamson and Wilson |
*California only participates in CRE surveillance
ESBL-E
| EIP site | Area under surveillance for ESBL-E |
|---|---|
| Colorado | Boulder |
| Georgia | Fulton |
| New Mexico | Bernalillo |
| New York | Monroe |
| Tennessee | Maury, Lewis, Wayne, Marshall |
iEC
| EIP site | Area under surveillance for iEC |
|---|---|
| California | Alameda |
| Colorado | Boulder |
| Connecticut* | Naugatuck Valley, South Central Planning Regions |
| Georgia | Fulton |
| Maryland | Baltimore City |
| Michigan | Washtenaw |
| Minnesota | Hennepin, Ramsey |
| New Mexico | Bernalillo |
| New York | Monroe |
| Oregon | Jackson |
| Tennessee | Maury, Lewis, Wayne, Marshall |
*Connecticut started iEC surveillance in July 2024.
A case is defined as any of the following bacteria isolated from an included specimen type collected from a person living in the surveillance area.
CRE
- Escherichia coli
- Enterobacter cloacae complex species (E. asburiae, E. bugandensis, E. cancerogenus, E. cloacae, E. hormaechei, E. kobei and E. ludwigii)
- Klebsiella species (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
iEC
- Escherichia coli
Specimen types included in case definitions
| Specimen type | CRE | CRAB | ESBL-E | iEC |
|---|---|---|---|---|
| Normally sterile site1 | Yes | Yes | Yes | Yes |
| Urine | Yes | Yes | Yes | No |
| Lower respiratory tract2 | N/A | Yes3 | N/A | No |
| Wound | N/A | Yes3 | N/A | No |
- 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.
- iEC: any resistance pattern (including non-resistant/fully susceptible strains).
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.
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 incident CRE, CRAB, and iEC 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.
EIP staff collect bacterial isolates associated with MuGSI cases and submit these to the CDC laboratory, which then:
- 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.
- Tests bacteria for antibiotic susceptibility using a reference method.
- Characterizes the molecular epidemiology of selected gram-negative bacteria.
- Contributes some isolates to the AR Isolate Bank.
- Shares results with EIP sites.
- Centers for Disease Control and Prevention, 2024. Emerging Infections Program, Healthcare-Associated Infections – Community Interface Surveillance Report, Multi-site Gram-negative Surveillance Initiative (MuGSI), Carbapenem-Resistant Enterobacterales Surveillance, 2022. Available at: https://www.cdc.gov/healthcare-associated-infections/media/pdfs/2022-CRE-Report-508.pdf
- Centers for Disease Control and Prevention, 2024. Emerging Infections Program, Healthcare-Associated Infections – Community Interface Surveillance Report, Multi-site Gram-negative Surveillance Initiative (MuGSI), Carbapenem-Resistant Acinetobacter baumannii Complex Surveillance, 2022. Available at: https://wcms-wp.cdc.gov/healthcare-associated-infections/media/pdfs/2022-CRAB-Report-508.pdf
- Centers for Disease Control and Prevention, 2024. Emerging Infections Program, Healthcare-Associated Infections – Community Interface Surveillance Report, Multi-site Gram-negative Surveillance Initiative (MuGSI), Extended-spectrum β-lactamase -producing Enterobacterales Surveillance, 2022. Available at: https://www.cdc.gov/healthcare-associated-infections/media/pdfs/2022-ESBL-Report-508.pdf