Healthcare Hygiene magazine October 2019 | Page 16

with respect to turnaround time on a diagnosis, so there’s
a significant challenge.”
Kenters, et al. (2019) confirms that C. auris is a budding
yeast that forms white, pink, or purple colonies on CHRO-
Magar and can be difficult to distinguish from C. glabrata:
“Some strains form aggregates of cells while others do
not. In contrast to most other Candida species, it grows
well at higher temperature (40-42° C) … First attempts to
identify C. auris using PCR directly from swabs, seem to
produce frequent ‘false positive’ results — positive in PCR,
negative in culture swabs. The first report of three cases of
nosocomial fungemia due to C. auris showed that this yeast
is commonly misidentified as C. haemulonii and Rhodotorula
glutinis using traditional phenotypic methods. These widely
used routine identification methods for yeasts are based on
phenotypic assimilation/fermentation tests using sets of
carbon and nitrogen compounds. An investigation of 102
clinical isolates, previously identified as C. haemulonii or C.
famata, showed that 88.2 percent of the isolates were in
fact C. auris, when confirmed by ITS sequencing. Several
studies have since reported that, in routine microbiology lab-
oratories, C. auris remains a problematic, difficult to identify
pathogen, because commercial biochemical identification
systems lacked this yeast in their databases.”
“C. auris transmission might be happening in a healthcare
facility where professionals are completely unaware; they
haven’t been able to detect it, or they are just missing it due
to false negatives, and it begs the issue of the importance of
having access to clinical microbiology services,” Rohde says.
“An expert in clinical microbiology and medical laboratory
needs to be part of this equation — and not just for Candida
auris, but for all pathogens in the healthcare setting.”
He continues, “People may argue with me on this, but
physicians and others in healthcare who are responsible for
patient outcomes, often do not have the kind of expertise,
education and background to immediately identify prob-
lematic organisms; not to detract from their other medical
diagnostic skills, but you cannot know intuitively which
microbe is infecting a patient without a medical laboratorian
conducting a test — it’s just not going to happen. Unless
of course you have those cases where a physician might
have the training and the background to do so, but that’s
rare. Unfortunately, healthcare has become so lean that
many laboratories are being consolidated, with their full
microbiology toolbox being moved to a central location. This
makes sense from an economic perspective, but sometimes
for clinicians, that’s not the best scenario.”
That becomes even more of an issue when considering
the long list of risk factors for patients, including immuno-
suppressed state, significant medical comorbidities, central
venous catheters, urinary catheters, recent surgery, paren-
teral nutrition, exposure to broad spectrum antimicrobials,
intensive care unit admission, and residence in a high-acuity
skilled nursing facility.
Sears and Schwartz (2017) point out that C. auris has been
recovered in samples from blood, catheter tips, cerebrospinal
fluid, bone, ear discharge, pancreatic fluid, pericardial fluid,
peritoneal fluid, pleural fluid, respiratory secretions (including
16
sputum and bronchoalveolar lavage), skin and soft tissue
samples (both tissue and swab cultures), urine, and vaginal
secretions. Clinically, it has been implicated as a causative
agent in fungemia, ventriculitis, osteomyelitis, malignant
otitis, complicated intra-abdominal infections, pericarditis,
complicated pleural effusions, and vulvovaginitis. They add
that, “Much like other Candida species, there is uncertainty
about the ability of C. auris to cause true respiratory, urinary,
and skin and soft tissue infections despite being isolated
from such samples.”
Cortegiani, et al. (2019) observe that, “It is likely that
many cases are missed, due to its misidentification with
other non-albicans Candida spp. (e.g., C. haemulonii) by
common microbiological diagnostic methods. Most of the
reports occurred in critically ill adults, with risk factors for
invasive fungal infections, such as immunosuppression,
surgery, or indwelling catheters. The most common form of
infection was candidemia, with a crude mortality of nearly
30 percent, but up to 70 percent in some reports.”
Cortegiani, et al. (2019) emphasize the criticality of
fighting C. auris in the intensive care unit (ICU): “Despite
implementation of countermeasures to limit colonization
and infections in ICUs, cases continue to be reported,
with a tendency to an endemic pattern. This reflects the
ability of C. auris to persist in the clinical environment,
facilitating its transmission within the critical-care setting.
Multidrug-resistant (MDR) pattern and has been frequently
observed (around 40 percent) with serious and complex
consequences for antifungal therapy.”
The researchers note that due to the progressive spread
of C. auris and treatment-related concerns, attention should
be focused on the following major issues: worldwide trans-
mission, anti-fungal treatment resistance, resilience and
mechanisms of transmission, Implementation of infection
prevention and control measures, and surveillance.
Let’s review each issue:
Antifungal treatment resistance
Cortegiani, et al. (2019) note that, “To date, there are
not established minimum inhibitory concentrations (MICs)
breakpoints for susceptibility testing of C. auris. Antifungal
susceptibility data from three continents demonstrated that
nearly 40 percent were MDR, with strains being resistant
to fluconazole (90 percent), amphotericin B (30 percent to
40 percent) and echinocandins (5 percent to 10 percent).
Moreover, a small percentage were also resistant to all an-
tifungals available. C. auris demonstrates a high propensity
to develop antifungal resistance under selective pressure.
Recent studies demonstrated mutations in ERG11 (encoding
lanosterol demethylase, the target of azoles) and FKS1
genes (encoding 1,3-beta-glucan synthase, the target of
echinocandins). The recommended antifungals for C. auris
treatment are mainly based on in-vitro testing and on the
most frequently retrieved resistance profiles. Echinocandins
are the recommended first-line treatment, pending specific
susceptibility testing. Lipid formulation of amphotericin
B should be an alternative in patients not responding to
echinocandins. Close monitoring to early detect therapeutic
failures and evolution of antifungal resistance is needed.
october 2019 • www.healthcarehygienemagazine.com