New Antibiotic-resistant Salmonella Bacteria Identified;
Study Appears in New England Journal of Medicine
Researchers from the University of Nebraska Medical Center have teamed
with the Nebraska Department of Health and Human Services and the Centers
for Disease Control to determine how antibiotic-resistant bacteria develop
to cause disease in humans. The investigation, which is detailed in an
article in the April 27 edition of the New England Journal of Medicine,
was prompted by the identification of a salmonella bacteria in a child
that was more resistant than any other previously found.
Salmonella is the most common cause of foodborne-related illnesses in
the United States. Outbreaks have been linked to a variety of foods, including
poultry and other meats, dairy products, fresh produce and dried cereals.
Salmonella typically causes short-term diarrhea in otherwise healthy individuals.
Serious disease may occur in very young children, the elderly, people with
impaired immune systems or people being treated with antibiotics.
Salmonella also is known to cause diarrhea in animals, including cattle.
The bacteria affect calves most severely.
The child who became sick lived in an area in which salmonellosis occurred
in at least two cattle herds. The investigation included the evaluation
of several different strains of salmonella isolated from cattle involved
with the outbreak. Those strains were compared with the isolate from the
boy as well as strains from the CDC and Nebraska. It is not known how the
child acquired the infection.
The feature that distinguishes this particular bacteria from others
is the presence of resistance to a group of antibiotics known as cephalosporins,
Dr. Fey said. This is particularly worrisome because there are very few
other antibiotics that can be used to treat children with salmonellosis
if the bacteria enters the blood stream.
Although organisms with a similar resistance pattern have been imported
into the United States on at least three previous occasions, Dr. Fred Angulo
of the CDCs Foodborne and Diahrreal Diseases Branch said the childs isolate
was the first example of an organism having developed this pattern of antibiotic
resistance within the United States. A national surveillance program
is in place to identify similar bacteria and prevent their spread.
Keeping hot foods hot and cold foods cold, and preventing cross-contamination
during food preparation can prevent the majority of foodborne diseases,
said co-author Thomas Safranek, M.D., epidemiologist for the State of Nebraska.
This project demonstrates the ability of nationwide monitoring programs
to detect new strains of antibiotic-resistant bacteria before they become
a general threat to the public. Continued monitoring by public health
officials did not find any additional cases in Nebraska.
Recognition that this type of problem can occur on the farm and ranch
is important to protect the health of farm and ranch families. I have no
doubt that many people thought salmonella infection occurred only through
contaminated food, said Steven Hinrichs, M.D., director of the Nebraska
Public Health Laboratory at UNMC, where the tests were conducted.
The researchers found that the mechanism for antibiotic resistance was
due to a bacterial virus that is capable of spreading to other bacteria.
This research is important in showing how the resistance developed and
in tracking further spread of the bacterial virus.
In addition to Drs. Fey and Hinrichs, other UNMC researchers involved
in the study were Mark Rupp, M.D., associate professor, Department of Internal
Medicine – Infectious Diseases and epidemiologist for Nebraska Health System,
and Peter Iwen, assistant professor, Department of Pathology & Microbiology.
UNMC is the only public academic health science center in the state.
Through its commitment to research, education, outreach and patient care,
UNMC has established itself as one of the country’s leading centers for
cancer research and treatment, solid organ transplantation and arthritis.
During the past year, nearly $31 million in research grants and contracts
were awarded to UNMC scientists, and UNMCs funding from the National Institutes
of Health increased by 28 percent, going from $16.2 million to $20.7 million.
UNMC’s educational programs are responsible for training more health professionals
practicing in Nebraska than any other institution.
NHS is the partnership of the former Clarkson Hospital, the first hospital
in Nebraska, and the former University Hospital, the primary teaching facility
for UNMC. The combined hospital is a 685-bed facility and serves approximately
25 percent of the Omaha-area market. NHS operates clinics and health care
centers serving Omaha, Plattsmouth and Auburn in Nebraska; and Council
Bluffs and Shenandoah in Iowa. In addition, NHS physicians operate more
than 300 outpatient clinics in 100 communities in four states. NHS provides
access to tertiary and primary care including world-class specialized treatment
such as solid organ transplantation, burn care, wound care, geriatrics,
bone marrow (stem cell) transplantation and other cancer treatments.