The rate of antibiotic resistance of S epidermidis over three-time points of specimen collection: penicillin (83.3%; 95.5% and 100%); erythromycin (72.2%; 86.4% and 100%); oxacillin (58.3%; 59.1% and 75%); trimethoprim-sulfamethoxazole (36.1%; 59.1% and 75%); ciprofloxacin (30.6; 36.4 and 0%); clindamycin (16.7%; 22.7% and 50%); levofloxacin (22.2%; 22.7% and 0%); tetracycline (19.4%; 22.7% and 0%); gentamycin (20.8%; 13.6% and 25%); doxycycline (1.4%; 0% and 0%).