A case-control study of nosocomial ampicillin-resistant enterococcal infection and colonization at a university hospital.
OBJECTIVE
To assess risk factors for colonization and nosocomial infection with ampicillin-resistant enterococci (ARE).


METHODS
Patients with ampicillin-resistant enterococci were compared retrospectively by logistic regression analysis with controls harboring susceptible strains. ARE were characterized by whole plasmid DNA analysis and restriction enzyme analysis of plasmid (REAP) DNA with EcoRI.


METHODS
The study was done at a 1,125 bed, tertiary-care teaching hospital in North Carolina with patients from whom enterococci were isolated from June 1, 1989, to March 30, 1991.


METHODS
The final study group comprised 44 cases with nosocomially-acquired colonization or infection with ARE and 100 controls with ampicillin-susceptible strains. Clinical and epidemiological risk factors for ARE were abstracted by chart review.


RESULTS
After controlling for age and site of infection, patients with ARE were more likely to have been admitted previously to our hospital and to have received third-generation cephalosporins and clindamycin. However, only advanced age and clindamycin therapy were independently associated with presence of ARE. REAP with EcoRI showed 20 groups of enterococci on 19 different wards.


CONCLUSIONS
These results suggest that ARE are endemic and multifocal in origin in our hospital and that advanced age and use of clindamycin are important selective risk factors for ARE colonization and infection.
Sexton
D J
DJ
Department of Medicine, Duke University Medical Center, Durham, NC 27710.
Harrell
L J
LJ
Thorpe
J J
JJ
Hunt
D L
DL
Reller
L B
LB
D000367:Age Factors; D000668:Ampicillin Resistance; D016022:Case-Control Studies; D002981:Clindamycin / Q000009:adverse effects; D015169:Colony Count, Microbial; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004269:DNA, Bacterial / Q000032:analysis*; D004587:Electrophoresis, Agar Gel; D016983:Enterococcus / Q000254:growth & development; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology; D006746:Hospital Bed Capacity, 500 and over; D006785:Hospitals, University / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008875:Middle Aged; D009657:North Carolina / Q000453:epidemiology; D010359:Patient Readmission; D010957:Plasmids; D015183:Restriction Mapping; D012189:Retrospective Studies; D012307:Risk Factors
D004269:DNA, Bacterial; D002981:Clindamycin