Molecular and epidemiological analysis of methicillin-resistant Staphylococcus aureus otorrhoea: hospital- or community-acquired?
OBJECTIVE
(1) To identify newly diagnosed cases of methicillin-resistant Staphylococcus aureus ear infection in our local population; (2) to determine the risk factors involved in these patients' clinical courses, and (3) to type the bacterial strains isolated and thus identify whether they were hospital- or community-acquired.


METHODS
Retrospective review of case notes, together with laboratory-based molecular studies in the departments of otolaryngology and medical microbiology in a university teaching hospital in Scotland, UK.


METHODS
Over a two-year period, 35 patients were identified with ear swabs positive for methicillin-resistant Staphylococcus aureus infection. These cases came from both hospital and community settings.


METHODS
(1) Identification of primary methicillin-resistant Staphylococcus aureus otorrhoea in patients with no previously documented colonisation; and (2) molecular typing of the strains isolated, using spa technology, to identify whether they were hospital- or community-acquired.


RESULTS
Of the 35 positive patients, 27 were previously known carriers of methicillin-resistant Staphylococcus aureus. The eight patients with newly diagnosed methicillin-resistant Staphylococcus aureus otorrhoea presented initially in the community. All of these patients had had contact with hospital staff (as in-patients or out-patients) in the weeks preceding development of their ear infection. Using the spa technique for molecular typing, we identified hospital-acquired ('epidemic') methicillin-resistant Staphylococcus aureus type 15 in all eight patients' isolates. All were sensitive to topical gentamicin.


CONCLUSIONS
In our cohort, hospital-acquired methicillin-resistant Staphylococcus aureus type 15 was the commonest cause of methicillin-resistant Staphylococcus aureus otorrhoea, despite the fact that these patients all first presented in the community. We believe that contact with hospital staff or health care workers is a risk factor for acquiring methicillin-resistant Staphylococcus aureus otorrhoea in the community.
Nassif
R G
RG
Department of Otolaryngology, Ninewells Hospital and University of Dundee Medical School, Dundee, Scotland, UK. ramgeorge@hotmail.com
Soliman
R
R
Edwards
D H
DH
Kara
N
N
Hussain
S S M
SS
D000293:Adolescent; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D017714:Community-Acquired Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology; D003428:Cross Infection / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D058889:Molecular Typing / Q000379:methods; D010032:Otitis Externa / Q000382:microbiology; D010035:Otitis Media, Suppurative / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D012189:Retrospective Studies; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000453:epidemiology / Q000382:microbiology*; D006113:United Kingdom / Q000453:epidemiology
D000900:Anti-Bacterial Agents