Minnesota Department of Health (MDH) Bug Bytes

December 26, 2001
Vol. 2: No. 21

Topics in this Issue:

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/
) 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 g/ml.; resistance was defined as a MIC of at least 4 g/ml.). The resistant isolates from chickens had higher levels of resistance (MICs ranging from 4 to 32 g/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.


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Updated Friday, November 19, 2010 at 02:16PM