Healthcare Hygiene magazine October 2019 | Page 18

isolates can be achieved in 48 hours or less leading to the
potential for bedside diagnostics twinned with molecular
epidemiology of nosocomial patterns of transmission.
Currently, it is not often known when patients become
colonized – whether from the hospital environment or
endogenous carriers – and the extent of carriage in the
community remains largely unexamined.”
Lockhart (2019) indicates that rapid identification of colo-
nized patients followed by isolation and contact precautions
can help stem the spread of resistant clones: “Real-time
detection methods can not only rapidly identify colonized
patients but may also contribute to the rapid detection
of resistance. Besides the existing laboratory-developed
tests, there is at least one commercially available PCR test
for the rapid detection of C. auris. There are currently two
real-time assays for detection of anti-fungal resistance in C.
auris, one for detecting azole resistance and the other for
echinocandin resistance, as well as a report that echinocandin
resistance can be detected using MALDI-TOF. These rapid
platforms may become essential for the rapid determination
of appropriate therapy.”
Environmental Persistence of C. auris
Short, et al. (2019) are sounding the alarm about the
environmental persistence of C. auris; in their study, they
found show that the ability of this multidrug-resistant yeast
to form cellular aggregates increases survival after 14 days,
which coincides with the upregulation of biofilm-associ-
ated genes. The researchers also caution, “Additionally,
the aggregating strain demonstrated tolerance to clinical
concentrations of sodium hypochlorite and remained viable
14 days post treatment. The ability of C. auris to adhere to
and persist on environmental surfaces emphasizes our need
to better understand the biology of this fungal pathogen.”
The researchers explain, “A key attribute of its pathogenic
repertoire is its ability to survive and persist in the environment,
yet the methods employed by this multidrug-resistant patho-
gen to disseminate throughout healthcare environments are
still not fully understood. This has profound implications for
decontamination and infection control protocols. Therefore,
understanding the mechanisms of spread and survival in the
hospital environment is critical, particularly as it persists
on hospital fomites, extensively colonize individuals, and
to survive as biofilms. Although traditionally biofilms are
associated with formation on an indwelling medical device or
on a mucosal substrate, recent investigations have suggested
that these communities can facilitate residence and survival
upon surfaces within a clinical setting. Despite the lack of
nutrients, these communities adapt to survive and display
increased tolerance to both heat and conventional disinfec-
tion treatments compared to a free-floating, equivalent cell.
C. auris has been shown to readily transmit between hospital
equipment, such as reusable temperature probes, and patients
suggesting limitations of current infection control strategies.
Commonly used disinfectants have been shown to be highly
effective when tested in suspension, yet our previous data
indicate that adherent C. auris cells can selectively tolerate
biocides, including sodium hypochlorite and peracetic acid,
in a substrate-dependent manner.”
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To test the theory of biofilm formation being employed
as an endurance strategy of C. auris, Short, et al. (2019)
performed survival studies using two phenotypically distinct
isolates based on their ability to form cellular aggregates.
The researchers report, “Similar to previous findings, C. auris
was found to remain viable for at least two weeks within
a dry environment, regardless of the organic material in
which it was suspended. It was shown that aggregating
cells survived considerably better than their single-cell
counterparts in PBS (>2.5 log2 cfu/mL) and 10% FCS (>4
log2 cfu/mL).”
The researchers add, “To confirm a role for biofilms in
facilitating environmental persistence, a panel of biofilm
associated genes, selected according to our group’s pre-
vious transcriptional characterization of C. auris biofilms,
was assessed. These genes were highly expressed across
both phenotypes; however, comparative analysis revealed
increased expression of approximately two-fold of several
of these genes, which are involved in adhesion, extracellular
matrix (ECM) production, and efflux pumps. ECM production
is a well-documented resistance mechanism in pathogenic
fungal biofilms of Candida spp. Increasing ECM production
could provide the necessary protection for C. auris to survive
extended periods of desiccation and retain viability following
terminal disinfection.”
Using Infection Prevention and Control to
Fight C. auris
Case investigation by public health entities such as the
CDC and others has demonstrated that C. auris patients
within similar geographic regions commonly had overlapping
stays in the same acute-care hospital or long-term care
facility, further supporting healthcare exposure as a key
method of transmission.
Given the risk of nosocomial transmission of this
multidrug-resistant pathogen, Sears and Schwartz (2017)
emphasize that, “…infection control measures are vital to
slowing the spread of C. auris. CDC recommends that all
hospitalized patients with C. auris infection or colonization
be treated using both Standard Precautions and Contact
Precautions and housed in a private room with daily
and terminal cleaning with a disinfectant agent active
against Clostridium difficile spores (Cadnum et al., 2017).
Receiving healthcare facilities should also be notified prior
to transfer of an infected or colonized patient. Infection
control precautions should be maintained until a patient
is no longer infected or colonized with C. auris although
there is uncertainty as to how best to monitor for ongoing
colonization (CDC, 2017). There are no clear data on the
efficacy of decolonization measures for patients colonized
with C. auris, however this has been attempted with
chlorhexidine in healthcare facilities during outbreaks.”
Kean, et al. (2018) articulate one of the greatest worries
about C. auris: “The ability of this organism to survive on
surfaces and withstand environmental stressors creates a
challenge for eradicating it from hospitals.”
An experience with surface cleaning and disinfection
to help combat C. auris in a U.S. healthcare facility was
documented by Marrs, et al. (2017) who reported on two
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