under the microscope
By Rodney E. Rohde, PhD, MS, SM(ASCP)CM SVCM, MBCM, FACSc
The Environment Can Be a Dangerous Place
C
omprising about 50 species, Acinetobacter are mostly
nonpathogenic environmental organisms. They are
common in places like the soil and water. The most common
infection-causing species is A. baumannii, which is a pleomorphic
aerobic gram-negative bacillus. These bacteria cause infections
in the blood, urinary tract, and lungs (pneumonia), or in wounds
in other parts of the body. It can also “colonize” or live in a
patient without causing infections or symptoms, especially in
respiratory secretions (sputum) or open wounds.
In 2017, Carbapenem-resistant Acinetobacter baumannii
(CRAB) caused an estimated 8,500 infections in hospitalized pa-
tients and 700 estimated deaths in the U.S. They constantly find
new ways to avoid antibiotics used to treat the infections they
cause. Antibiotic resistance occurs when the germs no longer
respond to the antibiotics designed to kill them. If they develop
resistance to the group of antibiotics called carbapenems, they
become carbapenem-resistant. When resistant to multiple
antibiotics, they are multidrug-resistant. Carbapenem-resistant
Acinetobacter are usually multidrug-resistant. Like last month’s
column on Clostridioides difficile (C. diff), CRAB is considered
a healthcare associated infections (HAIs).
Which patients are at increased risk for A. baumannii
(CRAB)? Acinetobacter infections typically occur in people in
healthcare settings. People most at risk include patients in
hospitals, especially those who:
●are
on breathing machines (ventilators)
●have
devices such as catheters
●have
open wounds from surgery
●are
in intensive care units
●have
prolonged hospital stays
Acinetobacter infection can be increased by many factors,
including prior antibiotic exposure, ICU admission, use of
a central venous catheter, and mechanical ventilation or
hemodialysis use. Acinetobacter species can be transmitted to
patients because of their persistence on environmental surfaces
and because of colonization of the hands of healthcare workers.
As I have often mentioned, all #SurfacesMatter all the time, to
everyone in the war on pathogen transmission. Acinetobacter
can live for long periods on environmental surfaces and shared
equipment if they are not properly cleaned and disinfected.
Where is this microbe found? Are there special
environmental niches for it?
A. baumannii is an aquatic organism and preferentially
colonizes those environments. This organism is often cultured
from hospitalized patients’ sputum or respiratory secretions,
wounds, and urine. In a hospital setting, Acinetobacter commonly
colonizes irrigating solutions and intravenous solutions.
When these infections occur, they usually involve (multi-) organ
systems with a high fluid content (e.g., urinary tract, respiratory
tract, peritoneal fluid, CSF, etc.). Outbreaks from these infections
are more often than isolated cases of nosocomial pneumonia.
Infections may complicate continuous ambulatory peritoneal
dialysis (CAPD) or cause catheter-associated bacteriuria.
www.healthcarehygienemagazine.com • may 2020
What are the differences between colonization and
infection?
Acinetobacter species tend to be of low virulence but
capable of causing infection in organ transplants and febrile
neutropenia. Most isolates recovered from hospitalized pa-
tients, particularly those recovered from respiratory secretions
and urine, represent colonization rather than infection. Thus,
one must exercise caution in determining whether the isolate
is due to colonization or is a true infection.
As an example, Acinetobacter isolated from the sputum
of a ventilated patient is more likely to represent colonization
than infection in the absence of fever, leukocytosis, increased
respiratory secretions, need for additional respiratory support,
or a new abnormality on chest imaging. The difference is
critical for proper antibiotic stewardship.
Which laboratory tests are commonly used for
diagnosis?
To identify the best antibiotic to treat a specific infection,
healthcare providers will send a specimen to the medical
laboratory for a typical culture workup and test any bacteria
that grow against a set of antibiotics (antibiotic susceptibility
test) to determine which are active against the microbe.
How can you avoid getting an infection?
● Hand hygiene: healthcare professionals and patients
(and others) must keep their hands clean to avoid
getting sick and spreading germs that can cause
infections
● Wash hands with soap and water or use alcohol-based
hand sanitizer, particularly before and after caring for
wounds or touching medical devices
● Remind healthcare providers and caregivers to clean
their hands before touching the patient or handling
medical devices
● Allow environmental services (housekeeping staff) and
healthcare staff to clean their room daily when in a
healthcare setting
In addition to hand hygiene, healthcare providers should
pay careful attention to recommended infection control
practices, including rigorous environmental cleaning (e.g.,
cleaning of patient rooms and shared equipment), to reduce
the risk of spreading these germs to patient. As a final
reminder, environmental services professionals (and others
who have responsibility for cleaning/disinfection) are the
secret weapon in proactive prevention of the transmission
of antibiotic-resistant and other pathogens.
Rodney E. Rohde, PhD, MS, SM(ASCP)CM SVCM, MBCM,
FACSc, serves as chair and professor of the Clinical Laboratory
Science Program at Texas State; associate director for the
Translational Health Research Initiative; as well as associate
dean for research in the College of Health Professions. Follow
him on Twitter @RodneyRohde / @TXST_CLS, or on his website:
http://rodneyerohde.wp.txstate.edu/
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