Surveillance of staphylococci susceptibility for antibiotics using the microdilution method

The susceptibility to antibiotics was determined for 192 coagulase-positive and 259 coagulase-negative staphylococci. The isolates were obtained in three regional laboratories in the Netherlands and tested using the microdilution method. After incubation the turbidity was measured in a photometer and the results were analyzed using a computer program. Less than 5% of the isolates of Staphylococcus aureus were resistant to any of the antibiotics, except amoxycillin (73% beta-lactamase producers). The percentages resistance for coagulase-negative staphylococci were generally higher: clindamycin (21%), erythromycin (33%), fusidic acid (14%), gentamicin (36%), doxycycline (12%), cotrimoxazole (27%) and ciprofloxacin (13%). The percentage beta-lactamase producers was 69%.De gevoeligheid voor antibiotica werd bepaald bij 192 coagulase-positieve en 259 coagulase-negatieve stafylokokken. De bacterien werden geisoleerd in drie regionale laboratoria en onderzocht met de microtiter-methode. De groei werd gemeten met een microtiterscanner en de resultaten werden verwerkt met een computerprogramma. De resistentie van Staphylococcus aureus tegen de onderzochte antibiotica was lager dan 5%, behalve dat 73% van de isolaten beta-lactamase vormde en dus resistent was tegen amoxicilline. Coagulase-negatieve stafylokokken waren vaker resistent, bijv. tegen clindamycine (21%), erytromycine (33%), fusidinezuur (14%), gentamicine (36%), doxycycline (12%), cotrimoxazol (27%) en ciprofloxacine (13%). Het percentage beta-lactamase vormers was 69%