Table 2

Pattern of bacterial growth on epidural catheters

Patient no.	Number of CFU cultured from								Duration of epidural, hours
	Extracorporeal segment	Skin swab	Subcutaneous segment			Tip segment
	EC1	SkSw1	SC1	SC2	SC3	T1	T2	T3
2	316.5	0	0	0	0	0	0	0	173
8	0	16.66	0	0	0	0	0	0	76.5
11	0	≥4165	0	0	0	0	0	0	73.5
12	0	3332	0	0	0	0	0	0	101
14	1532.7	0	0	0	0	0	0	0	69
18	0	≥4165	0	0	0	0	0	0	74
17	0	0	<8.3	0	0	0	0	0	99
1	0	≥4165	0	0	<8.3	16.7	0	0	77
13	0	≥4165	0	0	0	25.0	0	0	80
27	0	0	0	0	0	0	<8.3	0	73
29	0	≥4165	0	<8.3	0	0	0	<8.3	72
7	0	0	0	0	0	0	0	<8.3	76
9	0	0	0	0	0	0	0	<8.3	70
4	0	0	0	0	0	0	41.7	0	96
3	0	0	0	0	0	0	0	25.0	73
5*	≥4165	≥4165	1774.3	158.3	91.6	Diagnosed as positive and evaluated in clinical lab			96

Values indicate numbers of CFU or in situ duration (hours). No growth is indicated as 0 CFU. Lower detection limit 8.3 CFU. Upper detection limit 4165 CFU. The average duration of epidural therapy in non-colonized patients was 95 hours (range: 72–171 hours) (data not shown).
Many diagnostic microbiology laboratories define at least 100 CFU in quantitativestudies as a threshold indicating colonization.
*Patient with superficial infection.
CFU, colony-forming units; EC1, extracorporeal catheter segment; SC1, subcutaneous catheter segment 1 (superficial); SC2, subcutaneous catheter segment 2; SC3, subcutaneous catheter segment 3 (deep); SkSw1, skin swab; T1, catheter tip segment 1; T2, catheter tip segment 2; T3, catheter tip segment 3 (utmost tip in epidural space).