The individual had the same strain of Elizabethkingia that has been confirmed in 57 patients in Wisconsin since November.
Eighteen of those individuals have died. All of those infected had "at least one serious underlying illness" and most are older than 65, according to the Wisconsin of Health Services.
It's unknown whether the deaths were caused by the infection, the existing health conditions or the combination of both.
The number of cases in Wisconsin may continue to rise as the state health department continues to investigate possible cases.
Last month, the Michigan Department of Health and Human Services reported a case of the infection in their state. At the time, CDC spokesman Tom Skinner told CNN the Michigan case was not a complete surprise, given that health departments across the country were asked to be on the lookout for Elizabethkingia infections after the outbreak in Wisconsin was identified.
The bacteria are commonly found in soil, river water and reservoirs but do not commonly cause illness in humans. People with compromised immune systems or serious underlying health conditions are more at risk of infection. Previous outbreaks have been associated with health care settings.
"The majority of the infections identified to date have been bloodstream infections, but some patients have had Elizabethkingia isolated from other sites, such as their respiratory systems or joints," a statement released Tuesday from the Illinois Department of Public Health said.
Symptoms of Elizabethkingia infection include fever, shortness of breath, chills and a bacterial skin infection called cellulitis. The infection is often antibiotic resistant and therefore difficult to treat.
Illinois health officials said they will join Wisconsin and Michigan in working with the CDC to investigate this outbreak for which a source has not yet been identified.
Public health investigators have been interviewing patients and family members, taking environmental samples, taking samples from family members and patients in the same facilities and units as infected patients and reviewing medical records.