Fluoroquinolone resistance in the hospital versus outpatient setting

The Lomefloxacin International Surveillance Trial (LIST) is an in vitro testing program specifically designed to assess the antimicrobial activity of lomefloxacin against a wide range of clinical isolates from hospitals, clinics, and laboratories worldwide. Lomefloxacin was used as a representative quinolone to assess susceptibility patterns of fresh clinical isolates for new fluoroquinolones. Between June 1989 and December 1990, hospitals and clinics in France contributed zone-diameter data (5 mug disk) on approximately 45 000 clinical isolates. Data were collected by a processing center in the USA and were analyzed to identify susceptibility patterns by region and by country in addition to identifying trends in high-grade fluoroquinolone resistance. This analysis showed that an unusual and widespread pattern of fluoroquinolone resistance was observed for isolates tested at tertiary-care centers in France. In order to assess whether high levels of fluoroquinolone usage in these centers might be responsible for this level of resistance, a group of six French Community Clinics was added to the testing program in 1990. From May 1990 until April 1991, these clinics contributed data on almost 4500 strains to the testing program. In most cases, there was little or no difference between susceptibility patterns obtained in French Community Clinics and University Hospitals. The only statistically significant difference noted was for Staphylococcus aureus: only 70% of French University Hospital strains were susceptible to lomefloxacin compared with 92% of Community Clinic strains (p<0.05). This result is in agreement with other studies of new fluoroquinolones carried out in the USA and worldwide. Many of the fluoroquinolone-resistant strains of Staphylococcus aureus were also resistant to methicillin and other anti-bacterial drugs.