TABLE 3.

S. mutans cell survival of exposure to different drugs

Drugb	% cell survival in S. mutans straina:
	WT(pIB184)	ΔlexA(pIB184) mutant	ΔlexA(pVL3) mutant
Ofloxacin	(110 ± 5.0) × 10−3	(30 ± 20) × 10−3*	(4.8 ± 1.2) × 10−3*
Mitomycin C	(67 ± 1.0) × 10−4	(7 ± 2.1) × 10−4*	(1.6 ± 1.3) × 10−4*
Oxacillin	2.2 ± 1.0	1.6 ± 0.8	1.6 ± 0.7

^aAliquots of cells were removed at the introduction of the drug and after the treatment (h 24) to determine cell survival by spot plating onto THYE agar plates. The data are the averages and standard errors of results from three independent cultures. Statistical significance was determined by using Student's t test with the parametric P value cutoff set at <0.01 [*, mutant versus WT(pIB184)].

^bLethal concentrations of drugs were used.