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Streptococcus mitis sepsis in bone marrow transplant patients receiving oral antimicrobial prophylaxis
D C Classen1, J P Burke, C D Ford
1Division of Infectious Disease, LDS Hospital, Salt Lake City, Utah 84143.
Purpose:
Streptococcal infection has increasingly become a problem in neutropenic patients. We report on an outbreak of Streptococcus mitis sepsis in six bone marrow transplant patients receiving oral antimicrobial prophylaxis.
Patients And Methods:
We performed an epidemiologic study of all patients in our bone marrow transplant program from 1986 to 1988. The hospital and microbiology records for all patients were reviewed. All bone marrow patients were treated according to specified protocols, including an oral prophylactic antimicrobial regimen that was changed in late 1987 from vancomycin/polymyxin/tobramycin to norfloxacin. Identification, susceptibility testing, and whole cell protein analysis of streptococcal isolates were performed at the Reference and Antimicrobial Investigations Laboratories at the Centers for Disease Control.
Results:
We detected six cases of S. mitis sepsis among 21 patients undergoing bone marrow transplantation. No other concurrent pathogen was isolated from any patient at the time of the S. mitis bacteremia. Bacteremia developed within 72 hours of transplant in five of six patients and was associated with severe mucositis in four patients. An environmental study failed to reveal any common source for the outbreak, and whole cell protein analysis of all six S. mitis isolates revealed each to be distinct. Of 12 patients receiving oral vancomycin/polymyxin/tobramycin, one developed S. mitis bacteremia, versus five of nine patients receiving norfloxacin (p less than 0.03).
Conclusion:
We believe S. mitis bacteremia is a potential complication of bone marrow transplantation and is associated with antimicrobial prophylaxis with norfloxacin, especially in the setting of mucositis.
Insights
Streptococcus mitis sepsis is a risk for neutropenic patients undergoing bone marrow transplant. Norfloxacin prophylaxis was associated with increased S. mitis bacteremia, particularly with mucositis.
Area of Science:
- Infectious Diseases
- Hematology
- Transplantation Medicine
Background:
- Neutropenic patients are susceptible to infections.
- Streptococcal infections pose a growing threat in this population.
- Bone marrow transplant (BMT) recipients are at high risk for severe infections.
Purpose of the Study:
- To investigate an outbreak of Streptococcus mitis sepsis in BMT patients.
- To identify risk factors associated with S. mitis bacteremia in this cohort.
- To evaluate the role of oral antimicrobial prophylaxis in the outbreak.
Main Methods:
- Conducted an epidemiologic study of BMT patients from 1986-1988.
- Reviewed hospital and microbiology records.
- Analyzed S. mitis isolates using whole cell protein analysis.
- Compared S. mitis bacteremia rates between different prophylactic antimicrobial regimens.
Main Results:
- Six cases of S. mitis sepsis occurred in 21 BMT patients.
- Bacteremia developed early post-transplant in most cases and was linked to mucositis.
- No common environmental source was identified for the outbreak.
- Patients receiving norfloxacin prophylaxis had a significantly higher incidence of S. mitis bacteremia compared to vancomycin/polymyxin/tobramycin.
Conclusions:
- S. mitis bacteremia is a significant complication in BMT patients.
- Norfloxacin prophylaxis is associated with an increased risk of S. mitis bacteremia.
- Mucositis may exacerbate the risk of S. mitis sepsis in patients on norfloxacin.