Thursday, July 26, 2018

EID Journal: Elizabethkingia & Association with Tap Water & Handwashing, Singapore

Credit CDC


Ubiquitous in nature, and often multi-drug resistant, Elizabethkingia is a gram negative aerobic bacillus that only rarely causes opportunistic infections in (generally immunocompromised) humans, usually in hospital settings.
The genus Elizabethkingia includes not only E. meningoseptica, but E. miricola, E. endophytica, and E. anophelis - which in 2011 was initially found in the gut of an Anopheles gambiae mosquito (cite).
Despite its name E. anophelis has since been detected in the environment (both water and soil) and in health care settings (cite), and there's no solid evidence of transmission via mosquitoes.

While community acquired infections are rare, Elizabethkingia is viewed as an emerging nosocomial pathogen.  A few past outbreaks include:

A little over two years ago we were following an unusual event; for more than two months we watched an unprecedented 3-state Elizabethkingia anophelis outbreak unfold in America's Midwest (see WHO Takes Notice Of U.S. Elizabethkingia Outbreak).
Unlike the examples listed above - this was a community outbreak - and despite  intense multi-agency investigations, no epidemiological link has been found to explain the mysterious spike in the number of infected.
Had this outbreak occurred during the summer a mosquito vector might have been considered, but the first cases in this outbreak were detected in December and January, a time when mosquitoes aren't active in the upper Midwest. 
After 65 cases and 20 deaths were reported across 3 states - but mostly in Wisconsin - this outbreak ended as mysteriously as it began by early summer.

A paper published in Nature Comms the following year called Evolutionary dynamics and genomic features of the Elizabethkingia anophelis 2015 to 2016 Wisconsin outbreak strain found the Wisconsin isolates had demonstrated remarkable evolution over a short period of time.

They wrote:
Unlike other E. anophelis , the outbreak strain had a disrupted DNA repair mutYgene caused by insertion of an integrative and conjugative element. This genomic change probably contributed to the high evolutionary rate of the outbreak strain and may have increased its adaptability, as many mutations in protein-coding genes occurred during the outbreak. This unique discovery of an outbreak caused by a naturally occurring mutator bacterial pathogen provides a dramatic example of the potential impact of pathogen evolutionary dynamics on infectious disease epidemiology.
Two years later this  outbreak remains under investigation, and state health officials continue to monitor for any signs of a recurrence. 
Singapore, in the meantime, experienced a relatively small (3 case) nosocomial outbreak last year in a children’s intensive care unit.
Yesterday the EID Journal published a Dispatch describing the epidemiological investigation which found (as seen before) that hand washing stations were the likely source of the infection, which ironically, was spread to patients by HCWs after washing their hands.

The full article is worth reading, including their recommendation prioritizing the use of ABHR (Alcohol Based Hand Rubs) over hand washing in clinical care settings unless hands are visibly soiled.

Volume 24, Number 9—September 2018
Elizabethkingia anophelis and Association with Tap Water and Handwashing, Singapore

Chee-Fu Yung , Matthias Maiwald, Liat H. Loo, Han Y. Soong, Chin B. Tan, Phaik K. Lim, Ling Li, Natalie WH Tan, Chia-Yin Chong, Nancy Tee, Koh C. Thoon, and Yoke H. Chan

Author affiliations: KK Women’s and Children’s Hospital, Singapore.

We report an Elizabethkingia anophelis case cluster associated with contaminated aerators and tap water in a children’s intensive care unit in Singapore in 2017. We demonstrate a likely transmission route for E. anophelis to patients through acquisition of the bacteria on hands of healthcare workers via handwashing.

Elizabethkingia anophelis is an emergent pathogen first described from midgut specimens of the Anopheles gambiae mosquito (1). To date, there have been 2 reported confirmed E. anophelis outbreaks in humans. One occurred in an adult critical care unit in Singapore; the second was a large community outbreak in the United States (Wisconsin, Michigan, and Illinois) (25).

Water sources have been identified to harbor members of the genus Elizabethkingia, but the source of the community outbreak in the United States remains unknown (3,6). Effective interventions for outbreak control and transmission routes of E. anophelis remain unclear (3).

KK Women’s and Children’s Hospital (KKH) is the single largest public tertiary-care specialist women’s and children’s hospital in Singapore. The Children’s Intensive Care Unit (CICU) is a 16-bed unit that provides advanced monitoring and therapeutic technologies for critical pediatric cases.

On May 30, 2017, an alert was triggered due to the detection of 3 patients with Elizabethkingia spp. within 13 days in the unit. The incidence rate of the cluster, 2.87/1,000 bed-days, was ≈4 times higher than the average rate in the previous 5 years, 0.63/1,000 bed-days (2012 through 2016).

Initially, the strains were reported as E. meningoseptica, but subsequent testing confirmed the cluster to be associated with E. anophelis. We conducted an epidemiologic investigation to identify the source of the cluster. We also conducted a pragmatic experiment to test our hypothesis that E. anophelis could be transmitted by healthcare workers during handwashing with water contaminated with E. anophelis.

We showed how handwashing, despite the use of chlorhexidine soap, is a possible vehicle of transmission for E. anophelis from an affected tap outlet via the hands of healthcare workers to patients. Perinatal transmission of E. anophelis was previously documented to have occurred from a mother with chorioamnionitis to her neonate (11).
We confirmed that hand hygiene using ABHR was effective in removing E. anophelis from hands of healthcare workers, which has implications for infection control. Although current hand hygiene guidelines prioritize ABHR over handwashing when hands are not visibly soiled, there is no requirement to perform ABHR in addition to handwashing (12).
Therefore, most staff consider handwashing as complying with hand hygiene requirements. Our findings support using ABHR as the primary hand-hygiene method in clinical care, especially in critical care units and in outbreak situations involving waterborne organisms such as E. anophelis.
        (Continue . . . .)

Alcohol rub has some weaknesses as well; the CDC states that soap and water are more effective than hand sanitizers at removing or inactivating certain kinds of germs, like Cryptosporidium, norovirus, and Clostridium difficile 11-15.
All of which suggests that a traditional soap and water hand scrub followed by a healthy dollop of ABHR - particularly in certain clinical settings - may be the better overall solution. 
Achieving a high level of compliance, however (see APIC: The Impact Of The Hawthorne Effect On Hand Hygiene Audits), is another matter entirely.

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