All About Elizabethkingia anophelis

Over 40 have been infected, at least 15 have died, infected with a bacteria we don't know that much about—Elizabethkingia anophelis.

All who have been infected have been adults in Wisconsin, mostly seniors. Most have been over 65 years old and were reported to have had other health problems. Some were in nursing homes, others in hospitals. It's not clear how much pre-existing illness and how much the bacterial infection contributed to the deaths. It does not appear to be a problem for those healthy and outside of care facilities. Epidemiologists and lab workers—from the state and the CDC—are trying to figure out how this is happening.

Older woman feeling the cold in her home
Andrew Bret Wallis / Getty Images

Elizabethkingia anophelis Effects

This bacterial illness can lead to fever, shortness of breath, chills, and a skin infection – cellulitis – which can involve painful and sometimes reddened areas of skin. It has been found in the bloodstreams of patients and has created a sepsis clinical picture. It also causes meningitis.

Sometimes because of a patient's overall poor health, it's unclear if an Elizabethkingia infection is a colonizer—a bacteria acquired without causing illness; in someone already ill in the hospital, it's hard to tell if this is benign or causing problems. If not a colonizer, how much does the bug contribute to or actually create this ill health? It appears this bacteria, though often seen as a colonizer in other places, is causing its own damage in this outbreak centered in Wisconsin. The bacteria does make people sick—or sicker (it attacks primarily those already sick).


Microbiology laboratory tests are needed to determine if an infection is caused by Elizabethkingia anophelis.

If the bacteria is found in the blood or other body fluid, a sample of the body fluid can be used to grow the bacteria in a laboratory. The bacteria is grown on different microbiology laboratory plates with different substances, to see where the bacteria grows and where it cannot grow, along with other tests, thus identifying the bacteria present.

The problem is that rarer bacteria may not be as easily identified. Identification is not always instantaneous. It's easiest to first identify whether a bacteria is gram negative or positive. Elizabethkingia anophelis is gram negative. The problem is that many of the antibiotics that work on most gram-negative bacteria do not work on Elizabethkingia anophelis.

Other Similar Bugs

There are other species in the Elizabethkingia genus. These include Elizabethkingia meningoseptica (seen more commonly in human infections), Elizabethkingia miricola, and Elizabethkingia endophytica.

These are all aerobic, nonmotile, Gram-negative rods. The names of bacteria are not written in stone. They often change. Some of these species used to be part of the genus Flavobacterium.

These species are somewhat similar; 98.6 percent genetic sequence similarity to Elizabethkingia meningoseptica and 98.2 percent genetic similarity to Elizabethkingia miricola.


Elizabethkingia infections are bacterial and treated with antibiotics.The problem is the bacteria often does not respond to the standard antibiotics. The antibiotics that work against it may be surprising—and the last ones doctors would reach for. Initial identification of the bacteria (as gram-negative) would lead medical professionals to likely empirically treat with drugs that might not work.

Elizabethkingia infections are usually resistant to many antibiotics that commonly treat gram-negative bacteria—aminoglycosides, and β-lactam drugs, including carbapenems. These bacteria have been known to make extended spectrum β-lactamases (ESBL) and metallo-β-lactamases. That is to say, these bacteria can fight off the antibiotics that are often thought, but often erroneously, to be the biggest "guns" against bacteria. However, E. meningoseptica, which like all Elizabethkingia infections is gram-negative, does seem to respond to some drugs used for gram-positive bacteria. That is to say, Elizabethkingia infections have been known to respond to drugs like vancomycin, which is usually solely able to treat gram-positive infections.

There is less experience with treating Elizabethkingia anophelis, but prior to this outbreak, the bacteria was shown, without prior known antibiotic exposure, to be resistant to ampicillin, chloramphenicol, kanamycin, streptomycin, and tetracycline.

In this case, the bacteria appear susceptible to Bactrim (trimethoprim/sulfamethoxazole), fluoroquinolones (like levofloxacin or ciprofloxacin, perhaps), and Zosyn(piperacillin/tazobactam). Combination therapy is usually recommended—as is the potential addition of vancomycin.

Cases should be reported to public health officials—as should cases caused by similar bacteria. In particular, other Elizabethkingia species or related bacteria should be reported, as they may have been misidentified.

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