Genotyping by restriction endonuclease analysis compared to phenotyping by antibiogram for typing methicillin-resistant Staphylococcus aureus strains colonizing patients in a nursing home.
OBJECTIVE
To assist in defining patterns of methicillin-resistant Staphylococcus aureus (MRSA) colonization in a skilled nursing facility (SNF), we compared genotyping by field-inversion gel electrophoresis (FIGE) restriction endonuclease digestion analysis (REA) with phenotyping by antibiogram for defining strain relatedness among MRSA isolates from SNF patients.


METHODS
Prospective screening culture surveillance for MRSA among patients in a community SNF.


METHODS
Nares and stool swab cultures were obtained from newly admitted patients and from all patients quarterly. MRSA were isolated by oxacillin screening agar. Antibiograms were determined by the disk-diffusion method, and genotyping was by FIGE REA.


RESULTS
It was shown that, among isolates with the same genotypes, many had different antibiograms; among isolates with the same antibiograms, many had different genotypes; and the discriminatory indices for isolates of MRSA by FIGE REA and by antibiogram were 0.56 and 0.78, respectively.


CONCLUSIONS
Our study demonstrated that, in patients from one SNF, genotyping by FIGE REA identified two prevalent REA DNA types, but with variability of antibiogram patterns within each DNA type; the antibiogram also identified prevalent patterns with variability of REA DNA type within each antibiogram pattern. The discriminatory index of antibiograms alone, or of genotypes alone as determined by FIGE REA, was poor for strains of MRSA isolated from the SNF patients in our study.
Lee
Y L
YL
Infectious Disease Division, Department of Medicine, University of California Irvine, USA.
Thrupp
L
L
D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology; D004262:DNA Restriction Enzymes / Q000378:metabolism*; D005838:Genotype; D006801:Humans; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D000091402:Prohibitins; D015183:Restriction Mapping; D012866:Skilled Nursing Facilities; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification
C000717331:PHB2 protein, human; D000091402:Prohibitins; D004262:DNA Restriction Enzymes