Healthcare-Associated Infections: Reportable Multidrug-Resistant Organisms

Multidrug-resistant organisms (MDROs) are an ongoing threat to global public health. The potential for their rapid spread in health care settings, as well as the difficulty of treating infections caused by these organisms, underscore the need for health care facilities to be prepared to respond to their presence. Systematic, statewide surveillance for key MDROs is an essential part of controlling the spread of these organisms.

As of July 1, 2022, infection or colonization with two new carbapenemase-producing MDROs and one multidrug-resistant fungal organism will be added as reportable communicable disease conditions in Wisconsin. As of July 1, confirmed and probable cases of the following are considered Category II reportable communicable diseases:

• Carbapenemase-producing carbapenem-resistant Acinetobacter baumannii (CP-CRAB), P-03232b (PDF)
• Carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa (CP-CRPA), P-03232c (PDF)
• Candida auris (PDF)

Note that only carbapenemase-producing carbapenem-resistant Acinetobacter baumannii and carbapenemase-producing carbapenem-resistant Pseudomonas aeruginosa are included in the newly reportable conditions. While all carbapenem-resistant organisms are of concern, carbapenemase-producing organisms (CPOs) are particularly worrisome as carbapenemase enzymes can inactivate carbapenem antibiotics, as well as other beta-lactam antibiotics. Carbapenem antibiotics are often considered the last line of defense to treat multidrug-resistant infections. Moreover, some CPOs can transfer this ability to inactivate carbapenem antibiotics to other bacteria, which can lead to the spread of antibiotic resistance.

Confirmatory testing to identify these newly reportable organisms (to determine whether an organism is carbapenemase-producing, and to identify Candida auris) will continue to be done primarily by the Wisconsin State Laboratory of Hygiene. Confirmed and probable cases of these organisms will automatically be sent by WSLH to the Wisconsin Electronic Disease Surveillance System (WEDSS).

In addition to these newly reportable communicable disease conditions, as of May 1, 2022, carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) will be a Category II (rather than Category I) reportable communicable disease in Wisconsin. In addition, CRE reporting in the National Healthcare Safety Network (NHSN) will no longer be required for hospitals and nursing homes as of May 1, 2022, due to the availability of information about CRE cases in WEDSS.

This page is focused on the above organisms. For information about other reportable diseases caused by multidrug-resistant organisms, such as vancomycin-intermediate Staphylococcus aureus infection (VISA) and vancomycin-resistant Staphylococcus aureus (VRSA) infection, visit the Department of Health Services Disease Reporting webpage.

Wisconsin MDRO data

Collecting data on MDROs in Wisconsin is important for understanding the prevalence of these organisms, both statewide, as well as in specific regions. CP-CRE has been a reportable condition in Wisconsin since 2018. Current data on CP-CRAB, CP-CRPA, and Candida auris (C. auris) are based on voluntary submission of isolates by clinical laboratories to the Wisconsin State Laboratory of Hygiene. Statewide surveillance for these organisms will be possible going forward after July 1, 2022.

CP-CRAB

As shown in the map below, there was an increase in the number of positive CP-CRAB clinical and colonized cases identified in Wisconsin in 2021, as compared to 2020. Other data points of interest include:

• In 2020, three Wisconsin public health regions reported CP-CRAB cases compared to four regions in 2021.
• In 2021, 15% of CP-CRAB cases were found to be pan-resistant, meaning they were resistant to all antimicrobials against which they were tested.
• In 2021, among the 134 individuals for whom case history information was available, 90% (n=121) were either a current or former long-term care facility (LTCF) resident.

CP-CRE, CP-CRPA, and C. auris

*Cases include both clinical and colonization screening isolates. The numbers in the table are not de-duplicated across years. This means that an individual with a positive specimen in both 2020 and 2021 would be included in the numbers for both years.

Proportion of tested isolates that were carbapenemase-producing organisms

The below figure shows the proportion of carbapenem-resistant isolates tested for carbapenemase production that were found to be CPOs in 2021. As shown in the figure:

• Among the carbapenem-resistant Pseudomonas aeruginosa (CRPA) isolates tested, only a small proportion were found to be carbapenemase producing.
• Among the carbapenem-resistant Acinetobacter baumannii (CRAB) isolates tested, nearly all of the isolates were carbapenemase producing.
• For carbapenem-resistant Enterobacterales (CRE), about 20% of the isolates tested were carbapenemase producing. This is similar to information from CDC stating that in the United States, about 30% of CRE isolates are carbapenemase producing.

Reportable MDRO resources