Pseudoepidemic of streptococcal pharyngitis in a hospital pharmacy.
BACKGROUND
Streptococcus pyogenes has recently re-emerged as a significant pathogen causing disease ranging from pharyngitis to lethal systemic infection. Six hospital pharmacy employees were diagnosed as having streptococcal pharyngitis during 1 week, and antibiotic prophylaxis was requested to halt the outbreak.


OBJECTIVE
Outbreak investigation.


METHODS
Review of initial cases and prospective evaluation of the remaining pharmacy employees and the antigen detection test being used.


METHODS
Pharmacy and occupational health department of a university hospital.


METHODS
Sixteen employees of the hospital pharmacy and 19 other employees of the hospital.


RESULTS
The 6 pharmacy employees who had positive streptococcal antigen detection tests did not have symptoms suggesting streptococcal pharyngitis. Of the 10 remaining pharmacy employees, none had a positive throat culture for S pyogenes. Specificity of the antigen detection test being used was 53% (95% CI, 30%-75%) in prospective evaluation.


CONCLUSIONS
This was believed to represent a pseudoepidemic because none of the 6 cases had signs or symptoms typical of streptococcal pharyngitis, none of the remaining 10 pharmacy employees had positive throat cultures, and prospective evaluation found low specificity of the antigen detection test. Whereas use of an accurate test in such a low prevalence setting could have resulted in a higher percentage of results being false-positive, the low specificity of the antigen detection test being used also contributed to the pseudoepidemic.
Karchmer
T B
TB
University of Virginia Health System, Charlottesville, VA 22908, USA.
Anglim
A M
AM
Durbin
L J
LJ
Farr
B M
BM
D000900:Anti-Bacterial Agents / Q000627:therapeutic use; D003951:Diagnostic Errors / Q000706:statistics & numerical data; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D005189:False Positive Reactions; D006785:Hospitals, University; D006801:Humans; D007118:Immunoassay / Q000592:standards; D017053:Infection Control / Q000379:methods; D007841:Latex Fixation Tests / Q000592:standards; D016272:Occupational Health; D010564:Personnel, Hospital / Q000706:statistics & numerical data; D010607:Pharmacy Service, Hospital; D010612:Pharyngitis / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology / Q000382:microbiology* / Q000517:prevention & control; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D013290:Streptococcal Infections / Q000175:diagnosis* / Q000453:epidemiology / Q000209:etiology / Q000382:microbiology* / Q000517:prevention & control; D013297:Streptococcus pyogenes; D000078329:Workforce
D000900:Anti-Bacterial Agents