The Journal of Laryngology & Otology

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Molecular and epidemiological analysis of methicillin-resistant Staphylococcus aureus otorrhoea: hospital- or community-acquired?

R G Nassifa1 c1, R Solimana2, D H Edwardsa2, N Karaa1 and S S M Hussaina1

a1 Department of Otolaryngology, Ninewells Hospital and University of Dundee Medical School, Dundee, Scotland, UK

a2 Department of Medical Microbiology, Ninewells Hospital and University of Dundee Medical School, Dundee, Scotland, UK

Abstract

Objectives: (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.

Design and setting: 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.

Subjects: 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.

Main outcome measures: (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.

(Accepted March 22 2010)

(Online publication June 18 2010)

Correspondence:

c1 Address for correspondence: Mr Ramez George Nassif, Department of Otolaryngology, Ninewells Hospital, Dundee DD1 9SY, Scotland, UK. Fax: +44 (0)1382 632816 E-mail: ramgeorge@hotmail.com

Footnotes

Mr R G Nassif takes responsibility for the integrity of the content of the paper.

Competing interests: None declared