TABLE 3.

S. iniae infection of murine macrophages

Time (h)	No. of bacteria (CFU/ml)a
	9117			G1-6
	Extracellularb	Intracellular + attachedc	Intracellular + gentamicind	Extracellularb	Intracellular + attachedc	Intracellular + gentamicind
2	4.30 × 102 ± 85	1.19 × 104 ± 2.11 × 103	1.13 × 104 ± 1.5 × 103	2.68 × 102 ± 51	2.08 × 104 ± 4.76 × 10	1.51 × 104 ± 3.85 × 103
4	6.70 × 103 ± 4.83 × 103	1.14 × 104 ± 8.41 × 103	9.21 × 103 ± 2.5 × 103	1.30 × 103 ± 6.14 × 102	1.01 × 104 ± 2.88 × 103	6.38 × 103 ± 1.31 × 103
24	3.72 × 107 ± 1.71 × 107	3.02 × 107 ± 8.48 × 106	0	1.37 × 107 ± 4.12 × 106	7.91 × 106 ± 1.01 × 106	0

^aAll infections were performed with a 1-h incubation with gentamicin (100 μg/ml) and penicillin (5 μg/ml) to kill extracellular bacteria. Timing of infections began after this 1-h incubation. The medium was then replaced with either fresh medium without antibiotics (Intracellular + attached) or fresh medium containing 5 μg of gentamicin per ml and 1 μg of penicillin per ml for 24 h (Intracellular + gentamicin). Results are presented as means ± standard errors of the means from four macrophage infection experiments.

^bExtracellular numbers refer to the number of viable bacteria that have reemerged from the intracellular environment into the culture medium.

^cIntracellular + attached numbers refer to the viable intracellular bacteria and those that are strongly attached to the outside of the cell. Extracellular numbers and Intracellular + attached numbers come from the same well.

^dIntracellular + gentamicin numbers only refer to viable intracellular bacteria. No viable extracellular bacteria were recovered from these wells.