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Elizabethkingia anophelis: Exploring the outbreak of disease in the Midwest

Coyle, Amanda L. PhD, RN, FNP-BC

doi: 10.1097/01.NURSE.0000512887.67622.84

Elizabethkingia anopheles outbreak in the Midwest

Amanda L. Coyle is an assistant professor at The College at Brockport in Brockport, N.Y.

The author has disclosed no financial relationships related to this article.

ALTHOUGH ELIZABETHKINGIA is a common bacterium present in various environments, such as soil, river water, and reservoirs, it rarely causes human disease.1 In 2015 and 2016, however, cases involving significant morbidity and mortality in patients with Elizabethkingia anophelis (E. anophelis) in their bloodstream, lungs, or joints have been reported.2 Most of these cases have occurred in Wisconsin. Michigan and Illinois have also reported cases.2,3 State and local health departments have been collaborating with area healthcare providers and the CDC to investigate a source for these outbreaks, but none has been found.2,4

All states are now required to report any Elizabethkingia isolates to the CDC. This article provides an overview of the epidemiology, clinical considerations, and disease investigation of E. anophelis-related illness.

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The confirmed number of cases in the U.S. 2015-2016 outbreak of E. anophelis was 65; 20 people died.2,5 Wisconsin reported 63 cases with 18 deaths; Michigan and Illinois each reported one case and one death as well. The 65 cases in this outbreak all demonstrated a similar strain of E. anophelis.

A second and separate outbreak of E. anophelis took place in Illinois. In April 2016, the Illinois Department of Public Health reported an additional 10 Illinois residents with E. anophelis; 6 patients died. This was a different strain of E. anophelis than the one associated with the 65 cases reported from Wisconsin, Michigan, and Illinois.3 In both outbreaks, there have been no cases reported since spring 2016.4

Before the recent outbreaks, only 5 to 10 cases of Elizabethkingia infection had been reported per state per year. These small, isolated outbreaks typically occurred in healthcare settings.1 But the recent outbreaks haven't been confined to healthcare settings. Community-dwelling residents also were affected.6

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About E. anophelis

E. anophelis has been identified as the species that caused morbidity and mortality in patients affected by the recent outbreaks in Wisconsin, Michigan, and Illinois, and in the second cluster of cases in Illinois.3,4 These were the first times an E. anophelis outbreak had been seen in the United States. E. anophelis was previously identified as the causative agent in a handful of cases of human disease in the Central African Republic, Singapore, and Hong Kong.7-9

E. anophelis was first recognized as a novel species of the genus Elizabethkingia in 2011. (See Name changes and reclassifications.) It was isolated from the midgut of a mosquito during research that mapped organisms present in the Anopheles gambiae mosquito, a common malaria vector mosquito.7 However, it's important to note that no causal link between E. anophelis in the midgut of the mosquito to E. anophelis in human disease has been established. The initial Midwest outbreak occurred during the winter, when mosquitoes don't circulate. Further research into the significance of E. anophelis isolated in mosquitoes and its relevance to human pathogenesis is needed and ongoing.12,13

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Who's at risk?

Elizabethkingia is an opportunistic infection. In recent outbreaks, most infected patients were older than 65 with at least one significant underlying medical problem.2 Most patients experience bacteremia, although some have developed respiratory disease as well.2 The CDC says the deaths in the recent outbreaks can't be conclusively determined to be related to Elizabethkingia infection, a patient's underlying health problems, or a combination of those factors.2

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Clinical considerations

The signs and symptoms of Elizabethkingia disease are similar to many acute onset viral or bacterial illnesses. Patients can present with fever and chills. They may also experience shortness of breath and skin and joint complications consistent with cellulitis and bacterial infection.1 Diagnosis of E. anophelis is made by culturing body fluids including blood, and in some cases, respiratory secretions and/or joint aspirate. Septicemia often ensues. A high index of suspicion in those with multiple comorbidities and no clear etiology for illness is essential.

E. anophelis is a multidrug-resistant bacterium, so early antibiotic treatment is critical to improve patient outcomes. In recent U.S. isolates, E. anophelis has been susceptible to fluoroquinolones, rifampin, trimethoprim/sulfamethoxazole, and minocycline. Combination therapy is more effective than monotherapy.4

Both standard and contact precautions have been identified as prevention strategies for avoiding disease transmission from affected patients to others.14 Because the transmission mode remains unknown, conservative precautions are utilized.4

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Outbreak investigation

No source of E. anophelis has been identified in the Midwest outbreaks, despite the collaboration and cooperation of many agencies and multidiscipline experts. Wisconsin was the first state to identify potential cases, late in 2015. Public health employees consulted with the CDC, and statewide surveillance in Wisconsin quickly began. Healthcare providers, infection control specialists, and lab staff were notified of a potential outbreak, which led to rapid identification of additional cases.15

In January 2016, the CDC issued a nationwide alert, via Epi-X, the epidemic information exchange system, to ask for reports of any infections similar to the ones seen in Wisconsin and to send isolates to the CDC for further testing. This alert allowed for the detection of the isolated cases in Michigan and Illinois.2,3 It's now mandatory for all states to report any Elizabethkingia isolates to the CDC. Prior to the Midwest outbreaks, reporting of Elizabethkingia isolates wasn't mandatory.2

Disease detectives from state health departments and the CDC have done extensive interviews with patients regarding their potential exposure to healthcare facilities and healthcare products (medications, interventions, and medical devices). Patient histories of food and water intake and exposure, as well as their movements in institutional and community settings, were gathered. Product and environmental samples were obtained and tested from healthcare settings and communities. Nose and throat swabs from infected patients and their household contacts were collected and tested. Social network analyses, searching for institutional or community shared spaces, have been conducted. None of these investigations revealed a source of the E. anophelis outbreak in the three states in the Midwest.4 Testing, however, has allowed authorities to conclude that E. anophelis wasn't spread by a single source, such as a healthcare facility or product, nor was it spread from person to person.4 A transmission mode remains unknown.

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Nurses' role in disease outbreaks

Awareness of emerging infectious disease and outbreaks of illness is essential for nurses to deliver optimal care to their patients. Nurses have a strong foundation in pathophysiology, microbiology, epidemiology, genetics, evidence-based practice, and patient-centered care. They're also skilled in developing trust and communicating with patients. These skills make nurses an essential part of the healthcare team in disease detection.

Nursing care encompasses the management of a patient with sepsis. This includes frequent and careful monitoring of vital signs, physical assessment findings, hemodynamic parameters, and diagnostic study results. Physical assessment should focus on indicators of tissue perfusion, such as vital signs, level of consciousness, amplitude of peripheral pulses, capillary refill time, skin color and temperature, and urine output.16 Nurses should alert and coordinate with the healthcare team when interventions need adjustment. Timely acquisition of specimens for culture, as well as administration of antibiotics, is essential.17 Fluid resuscitation and titration of I.V. vasopressors are also key nursing interventions in a patient with sepsis.17

Nurses need to be continually vigilant and up-to-date regarding emerging infectious disease and the essential role that collaborative partnering has in disease investigation. Remaining intellectually curious regarding emerging infectious diseases, asking questions, and entering into discussions with members of the interdisciplinary healthcare team and with patients may spark recogntion of an undiscovered aspect of disease investigation.

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Name changes and reclassifications

The genus of the bacteria Elizabethkingia has gone through several name iterations and reclassifications as the science of genome identification has rapidly evolved. Knowledge of Elizabethkingia etymology is essential to case reporting, but state and local labs report bacteria names inconsistently and labs need specialized equipment to distinguish the different strains of Elizabethkingia.10

Elizabeth O. King was a CDC scientist who first discovered the bacteria in 1959 while studying meningitis in infants.11 She originally gave the bacteria the family name of Flavobacterium meningosepticum. In 1994, the bacteria were reclassified to the genus name of Chryseobacterium meningosepticum. Again, in 2005, the bacteria were reclassified to the genus Elizabethkingia.

Genome mapping has allowed for further identification of species within the genus Elizabethkingia.11 These species are E. meningoseptica, E. miricola, E. anophelis, and E. endophytica. The first three of these species have been known to cause disease in humans.9 Specimen reporting guidelines include any of the previous and current names of Elizabethkingia bacteria.10

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2. Centers for Disease Control and Prevention. Recent outbreaks. 2016.
3. Illinois Department of Public Health. Cluster of Elizabethkingia cases identified in Illinois. 2016.
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