Antimicrobial Stewardship: Antibiogram
Antibiotic resistance is one of the greatest clinical and public health challenges. An antibiogram is one method to summarize and trend the antibiotic susceptibility profiles of a population of bacteria isolated from patients.
Antibiograms are useful for monitoring resistance patterns over time in a healthcare setting or across a group of facilities. They can also help guide a clinician’s selection of the best empiric antimicrobial therapy when cultures are pending, using the local trend as a proxy until more specific results are available. Health systems may also incorporate these results into their drug formulary options or as part of antimicrobial stewardship team policies to reinforce the use of antimicrobials that demonstrate less resistance.
Typically, antibiograms are created at the facility level, however, sometimes there are not enough clinical isolates to provide susceptibility estimates. This is common for smaller inpatient facilities and for less commonly isolated bacterial species. Pooling of culture data across facilities is one strategy to overcome these limitations. On this webpage, you can find Wisconsin statewide antibiograms and links to other Wisconsin antibiograms.
Wisconsin statewide inpatient antibiograms
The Wisconsin Healthcare-Associated Infections Prevention Program summarized antibiotic resistance (AR) data submitted to the National Healthcare Safety Network (NHSN) by Wisconsin hospitals to create statewide antibiograms.
Methodology
The 2025 statewide antibiograms are based on AR data submitted by 134 Wisconsin hospitals to the NHSN for 2025, and include data from 74 general acute care hospitals, 55 critical access hospitals, two inpatient rehabilitation facilities, two orthopedic hospitals, and one inpatient psychiatric facility. This represents 82% of all Wisconsin hospitals that are enrolled in and eligible to submit AR data to NHSN.
| Bed size | Number of hospitals |
|---|---|
| Small (1–49 beds) | 76 |
| Medium (50–149 beds) | 37 |
| Large (equal to or more than 150 beds) | 21 |
All AR data submitted by Wisconsin hospitals for 2025 is reflected in the antibiograms. Of hospitals that reported AR data in 2025, most (89%) reported data for all 12 months. A small number of hospitals reported AR data for fewer than 12 months.
Species with at least 30 clinical isolates were included. Duplicate isolates were excluded based on the NHSN exclusion criteria. Of the available antibiotic susceptibility results, clinically relevant drug-bug pairs were included in fungal, Gram-positive, and Gram-negative antibiograms for all specimen types and blood cultures. Clinically relevant drug-bug pairs were included in Gram-positive and Gram-negative antibiograms for urine cultures. A “heat map” was applied to assist with interpretation, using a blue gradient to visually depict percent susceptible. Darker blue is associated with lower susceptibility.
2025 antibiograms
Gram-Positive
Gram-Negative
Fungal
Gram-Positive
Gram-Negative
Fungal
Gram-Positive
Gram-Negative
Limitations
These statewide antibiograms have limitations. Susceptibility testing methodologies and application of Clinical and Laboratory Standards Institute (CLSI) breakpoints may have differed across facilities. The NHSN data formatting does not allow for separation of methicillin-resistant Staphylococcus aureus (MRSA) from methicillin-susceptible Staphylococcus aureus (MSSA) in the antibiograms.
Because geographic information cannot be accounted for in these antibiograms, information should not be used to inform clinical treatment decisions. These antibiograms and future antibiograms will be used to understand changes in the susceptibility patterns of clinically important bacterial organisms over time.
Future directions
The HAI Prevention Program plans to update each antibiogram annually.
Additional resources
- Wisconsin Diagnostic Laboratories antibiograms:
- Clinical Laboratory Standards Institute (CLSI)
- Gram-negative Surveillance of Wisconsin Antibacterial Susceptibility Patterns, 2016 (PDF)
Questions about HAIs? Contact us!
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