Minnesota Department of Health (MDH) Bug Bytes
December 26, 2001
Vol. 2: No. 21
1. Update - Knee Surgery Deaths
2. Vaccine Shortages - DTaP and PCV
3. Loose Stools in School
4. Antibiotics and Chickens
1. Update - Knee Surgery Deaths
In the last issue of Bug
Bytes we provided an update on our investigation of three
deaths following knee surgery at two separate Minnesota hospitals.
Patient 1 had received a knee osteochondal allograft, and
patients 2 and 3 had undergone total knee replacement surgery.
Blood cultures from patient 1 prior to his death grew Clostridium
sordellii. The cause of death in patients 2 and 3 remains
unexplained. Culture of non-implanted knee tissue from the
same cadaveric donor source for Patient 1 has yielded growth
of Clostridium sordellii at CDC.
CDC has received at least 5 other reports of knee surgery and allograft recipients infected with clostridial species in four states including Minnesota. These cases, and the risk factors for contamination of allograft tissue from tissue harvesting and procurement to processing by tissue banks, are being investigated by CDC in cooperation with MDH.
2. Vaccine Shortages - DTaP and PCV
In response to a supply shortage, the Advisory Committee on
Immunization Practices (ACIP) is updating recommendations
for the diphtheria and tetanus toxoids and acellular pertussis
vaccine (DTaP). DTaP is recommended as a five-dose series:
three doses given to infants at ages 2, 4, and 6 months, followed
by two additional doses at age 15-18 months and at age 4-6
years. During the ongoing shortage of DTaP, ACIP recommends
that providers who do not have enough DTaP to vaccinate all
children with five doses give priority to vaccinating infants
with the first three doses. To assure an adequate supply of
DTaP to vaccinate infants, providers should first defer vaccination
of children aged 15-18 months with the fourth DTaP dose. If
deferring the fourth dose does not leave enough DTaP to vaccinate
infants, then the fifth DTaP dose (given to children aged
4-6 years) should also be deferred. Children traveling to
a country where the risk for diphtheria is high should be
vaccinated according to the Recommended Childhood Immunization
Schedule. When the DTaP shortage ends, providers should recall
all children who missed a DTaP dose and administer the vaccine.
Vaccination of children aged 4-6 years is needed to assure
immunity to pertussis, diphtheria, and tetanus during the
elementary school years.
The ACIP has also issued revised recommendations for pneumococcal
conjugate vaccine (at http://www.cdc.gov/mmwr/preview/
mmwrhtml/mm5050a4.htm) to decrease vaccine demand until
supplies are adequate. The revised recommendations call for
a reduced number of doses until the vaccine shortage is resolved.
The most notable change is for infants who receive their first
dose before 6 months of age. For these infants, vaccination
with a maximum of 3 doses is recommended, with deferral of
the fourth dose. Two key principles underlie the interim recommendations.
First, providers should conserve vaccine supply by decreasing
the number of doses administered to healthy infants rather
than leaving some children in the group recommended for vaccination
completely unprotected. Second, reductions in pneumococcal
conjugate vaccine use should be made by all providers, regardless
of the current vaccine supply in their own practice. Moreover,
as the amount of vaccine used decreases, providers should
reduce the size of their vaccine orders so that available
vaccine can be distributed as widely as possible.
3. Loose Stools in School
Last week we investigated an outbreak of gastrointestinal
illness at an elementary school in Becker County. The attack
rate at the school was high, with 33 of 78 students affected.
Illnesses were clustered in time, with most onsets ranging
from 12/14-12/17, suggesting a point source outbreak. Thirty
students were interviewed; all 30 were ill with diarrhea,
24 had fever (range of temps, 99-104 degrees), 21 reported
vomiting, and 2 had bloody stools. At the time of the interviews,
only nine of the ill had recovered; their duration of illness
was about 3 days. Food items, including some self-service
items, were implicated in the preliminary statistical analysis.
Similarly, there was opportunity for cross contamination of
utensils.
Six stools were collected and tested at MDH; all 6 were positive for Shigella sonnei. Control of this highly contagious bacteria is based on frequent and thorough hand washing. Treatment with antibiotics may shorten the duration of illness and the length of time that people are infectious to others. The outbreak strain is resistant to amoxicillin but susceptible to trimethoprim-sulfamethoxazole and third generation cephalosporins.
4. Antibiotics and Chickens
In the October 18 issue of the New England Journal of Medicine
was an article highlighting some work done by us in cooperation
with CDC and other EIP sites in Maryland, Georgia, and Oregon.
The combination of the streptogramins quinupristin and dalfopristin
was approved in 1999 for the treatment of vancomycin-resistant
Enterococcus faecium infections. Since 1974, another
streptogramin, virginiamycin, has been used at subtherapeutic
concentrations to promote the growth of farm animals, including
chickens. To determine the frequency of quinupristin-dalfopristin-resistant
E. faecium, we purchased chickens from grocery stores
and cultured them in our laboratory using selective media.
Between July 1998 and June 1999, samples from 407 chickens from 26 stores in the four states were cultured, as were 334 outpatient stool samples. Quinupristin-dalfopristin-resistant E. faecium was isolated from 237 chickens and three stool specimens. The resistant isolates from stool had low-level resistance (minimal inhibitory concentration [MIC], 4 µg/ml.; resistance was defined as a MIC of at least 4 µg/ml.). The resistant isolates from chickens had higher levels of resistance (MICs ranging from 4 to 32 µg/ml).
The low prevalence and low level of resistance of these strains in human stool specimens suggest that the use of virginiamycin in animals has not yet had a substantial influence in humans. However, foodborne dissemination of resistance may increase, as the clinical use of quinupristin-dalfopristin increases.
HAPPY HOLIDAYS & A HEALTHY 2002!!
Bug Bytes is a combined effort of the Infectious Disease Epidemiology, Prevention and Control Division and the Public Health Laboratory Division of MDH. We provide Bug Bytes as a way to say THANK YOU to the infection control professionals, laboratorians, local public health professionals, and health care providers who assist us.
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