Antibiotic-Resistant Strain of E. Coli Increasing
Among Senior Citizens in Nursing Homes
Spread of E. coli ST131 already a pandemic but has
received little attention in the U.S. making development of
strategies to halt further emergence and spread of these strains a
public health priority
March 12, 2013 - Antibiotic-resistant Escherichia
coli (E. coli) continues to proliferate, driven largely by expansion of
a strain of E. coli know as sequence type ST131. A new study points to
hospitals and long-term care facilities (LTCF) as settings in which this
antibiotic-resistant strain is increasingly found, particularly among
"The expansion of E. coli strain ST131 is
recognized as a pandemic, but has received comparatively little
attention in the United States," said Ritu Banerjee, lead investigator
of the study.
"Alarmingly, the pace of new antibiotic development
has not kept up with the emergence of antibiotic-resistant E. coli,
making development of strategies to halt further emergence and spread of
these strains a public health priority."
The study is published in the April issue of
Infection Control and Hospital Epidemiology, the journal of the
Society for Healthcare Epidemiology of America.
E. coli is the most common gram-negative pathogen,
causing both gastrointestinal disease and extra-intestinal infections
such as pneumonia, meningitis, and bloodstream, urinary tract,
abdominal, and wound infections.
Strains of E. coli that are resistant to single or
multiple classes of antibiotics are becoming more prevalent. E. coli
ST131 is commonly associated with fluoroquinolone resistance.
In this retrospective study, investigators
evaluated nearly 300 consecutive patients in Olmsted County, Minnesota
with extra-intestinal E. coli infections and found ST131 to be a
dominant, antimicrobial-resistant clonal group associated with older
age, long-term care facility residence, complicated infections, history
of urinary tract infection, and prior antimicrobial use.
LTCF residence was the strongest predictor of ST131
infection, with LTCF residents having 8 times the risk of contracting E.
coli ST131 compared with non-LTCF residents.
Escherichia coli (E. coli)
bacteria normally live in the intestines of people and animals.
Most E. coli are harmless and actually are an important part of
a healthy human intestinal tract. However, some E. coli are
pathogenic, meaning they can cause illness, either diarrhea or
illness outside of the intestinal tract. The types of E. coli
that can cause diarrhea can be transmitted through contaminated
water or food, or through contact with animals or persons.
E. coli consists of a diverse
group of bacteria. Pathogenic E. coli strains are categorized
into pathotypes. Six pathotypes are associated with diarrhea and
collectively are referred to as diarrheagenic E. coli.
Elderly most endangered
This trend coincides with the increasing prevalence
of ST131 among patients 65 years and older. It is likely that extensive
antibiotic exposure, close contact with other antibiotic-exposed
individuals, age and health-associated alterations in intestinal
microbiota all contribute to the high prevalence of ST131 among the
Patients with ST131 isolates were often treated
with ineffective antibiotics at first and as a result they had recurrent
or persistent symptoms. In the cohort, ST131 isolates were also more
than twice as likely to be healthcare-associated infections as compared
to community-associated infections.
"The finding that clonal expansion of ST131 is
occurring primarily in healthcare and long-term care facilities
indicates an urgent need for improved antibiotic use and infection
control practices within such institutions, both to reduce selection for
ST131 and to block further transmission. Efforts that focus on reducing
overuse and misuse of fluoroquinolones are likely to have the greatest
impact on ST131 prevalence, given the strong association between ST131
and fluoroquinolone resistance," said Banerjee.
Published through a partnership between the Society
for Healthcare Epidemiology of America and The University of Chicago
Press, Infection Control and Hospital Epidemiology provides
original, peer-reviewed scientific articles for anyone involved with an
infection control or epidemiology program in a hospital or healthcare
facility. ICHE is ranked 15 out of 140 journals in its discipline in the
latest Journal Citation Reports from Thomson Reuters.
SHEA is a professional society representing more
than 2,000 physicians and other healthcare professionals around the
world with expertise in healthcare epidemiology and infection prevention
and control. SHEA's mission is to prevent and control
healthcare-associated infections and advance the field of healthcare
epidemiology. The society leads this field by promoting science and
research and providing high-quality education and training in
epidemiologic methods and prevention strategies. SHEA upholds the value
and critical contributions of healthcare epidemiology to improving
patient care and healthcare worker safety in all healthcare settings.
Visit SHEA online at
http://www.shea-online.org, on Twitter @SHEA_Epi and Facebook
Ritu Banerjee, Brian Johnston, Christine Lohse,
Stephen B.Porter, Connie Clabots and James R. Johnson. "Escherichia coli
Sequence Type 131 Is a Dominant, Antimicrobial-Resistant Clonal Group
Associated with Healthcare and Elderly Hosts." Infection Control and
Hospital Epidemiology 34:4 (April 2013).
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