Table 2.

Antibacterial efficacy as established using the modified Kirby-Bauer test*

Time after elution (hours)	0	6	24	72	168	336	504	672
Palacos R-G
Staphylococcus aureus 7323	+	±	±	±	−	−	NT	NT
Coagulase-negative staphylococcus 5277	−	−	−	−	−	−	NT	NT
Copal
Staphylococcus aureus 7323	++	+	+	+	+	+	+	+
Coagulase-negative staphylococcus 5277	++	++	++	++	+	+	+	+

* Inhibition zones against a gentamicin-sensitive Staphylococcus aureus 7323 and a gentamicin-resistant coagulase-negative staphylococcus 5277 strain for Palacos R-G and Copal bone cement at different times after elution; sensitivity is recorded with modified Kirby-Bauer test if an inhibition zone of at least 3 mm is present around the cement sample; therefore, zones with a width 3 mm or less were scored with (−), zones between 4 and 10 mm were scored with (±), zones between 11 and 20 mm were scored with (+), and zones larger than 21 mm were scored with (++); modified Kirby-Bauer test was performed in duplicate; NT = not tested.