Objectives:

Staphylococcus lugdunensis (Sl) is a coagulase-negative Staphylococcus known as a rare cause of severe infections. As a consequence of two serious infections we decided to optimise identification of Sl and make a comprehensive epidemiological analysis of the Sl infections in Viborg County (population: 235 000), Denmark.

Methods:

All specimens send to department of Clinical Microbiology, Viborg County from July to December 2002 were included. Specimens were inoculated on Columbia agar plates containing 5% sheep blood. Suspected staphylococci were identified by catalase, slide coagulase test, colony phleomorphism, b-haemolysis, and examined for a characteristic ‘Eikenella-like‘ smell after 2 days of incubation. Strains suspected to be Sl were examined with API-ID-32-Staph. All cases positive with Sl were followed up by a telephone interview with the general practitioners or by reading the hospital records.

Results:

When cultured on sheep blood agar, Sl develops a characteristic smell on the second day of culturing. This smell together with b-haemolysis and colony phleomorphism is very helpful as a first step screening for the presence of Sl in the routine cultures. The total incidence of Sl infection in Viborg County was 4/10 000 per year. Sl infections were three times more common in general practice than in hospitals. Sl was found in 13% of all microbiologically examined abscesses with bacterial growth from general practice. Most patients were otherwise healthy. All patients needed antibiotics and/or surgical treatment. Most of the infections were abscesses, and 70% of them were monocultures. The localisation of the infections seems to be age dependent.

Conclusions:

Calculated from our incidences 3–5% of the otherwise healthy population will be Sl infected at least once during their life span, and our findings are most probably a low estimate. Sl is an important and common cause of abscesses. It should be looked for and identified in all bacteriological examinations. Furthermore the microbiologists should make all general practitioners and hospital physicians acquainted with its name, the pathology and the risk of serious complications.