Methicillin-resistant Staphylococcus aureus carriage in a long-term care facility: hypothesis about selection and transmission.
BACKGROUND
many studies have identified long-term care facilities (LTCFs) as reservoirs of patients carrying methicillin-resistant Staphylococcus aureus (MRSA). However, few data about the mechanisms of MRSA diffusion in these settings are available.


OBJECTIVE
the purpose of our study was to suggest hypothesis on the possible ways of MRSA transmission to residents in or outside a LTCF.


METHODS
data concerning patients on the day of the survey and within the preceding year were collected. Multivariate analysis was performed by logistic regression to identify characteristics associated with MRSA carriage. MRSA strains were analysed by pulsed-field gel electrophoresis (PFGE) and the relatedness between DNA patterns was studied with Gel Compar software.


RESULTS
the prevalence of MRSA carriage was 37.6%. Treatment with fluoroquinolones or third-generation cephalosporins [odds ratio (OR) = 12.07; 95% confidence interval (CI) = 5.90-24.7], treatment with other antimicrobial agents (OR = 4.40; 95% CI = 2.43-7.97), at least one medical imaging session (OR = 5.08; 95% CI = 2.66-9.69) within the 12 preceding months, and the presence of a subcutaneous catheter on the day of the survey (OR = 3.09; 95% CI = 1.87-5.10) were independently associated with MRSA carriage. Twenty-eight of the 38 strains tested were clustered in two major groups. In each of these groups, strains had at least a 90% relatedness. These strains were isolated in patients hospitalised in different areas of the LTCF.


CONCLUSIONS
we identified that both molecular and epidemiological arguments support the hypothesis of the possibility of MRSA cross-transmission inside the LTCF. Further studies are needed to confirm and explain the association identified between MRSA carriage and medical imaging.
Eveillard
Matthieu
M
Hôpital Louis Mourier (AP-HP), Microbiologie-hygiène, France. maeveillard@chu-angers.fr
Charru
Philippe
P
Rufat
Pierre
P
Hippeaux
Marie-Claire
MC
Lancien
Evelyne
E
Benselama
Farida
F
Branger
Catherine
C
D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000009:adverse effects / Q000627:therapeutic use; D002353:Carrier State / Q000453:epidemiology; D002404:Catheterization / Q000009:adverse effects; D002511:Cephalosporins / Q000009:adverse effects / Q000627:therapeutic use; D003428:Cross Infection / Q000635:transmission; D003952:Diagnostic Imaging / Q000009:adverse effects; D005260:Female; D024841:Fluoroquinolones / Q000009:adverse effects / Q000627:therapeutic use; D006707:Homes for the Aged / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D016106:Methicillin Resistance; D008954:Models, Biological; D015995:Prevalence; D013203:Staphylococcal Infections / Q000635:transmission*; D013211:Staphylococcus aureus / Q000502:physiology*
D000900:Anti-Bacterial Agents; D002511:Cephalosporins; D024841:Fluoroquinolones