Table 1.

Antibiotic resistance phenotypes of E. coli and enterococci colonies isolated from soil amended with biosolids (days 0, 35 and 77) and carrots at harvest (day 77) in a greenhouse study. Note: Soil in pots were amended with biosolids on day 0. On days 0 and 35, soil E. coli and enterococci colonies were isolated from agar plates supplemented with antibiotics (ampicillin, tetracycline, or ciprofloxacin for E. coli and ampicillin or tetracycline for enterococci). On Day 77, soil and carrot E. coli colonies were isolated from non-supplemented plates (no E. coli growth was observed on antibiotic-supplemented plates and no enterococci growth was observed on antibiotic-supplemented or non-supplemented plates).

E. coli colonies isolated from mTEC agar
Antibiotic supplement		Ampicillin		Ciprofloxacin		Tetracycline		None
Day		0	35	0	35	0	35	77 (soil)	77 (carrots)
Resistance phenotype	Ampicillin	19	29	13	1	8	1	6	13
	Chloramphenicol	1	6	13	0	6	0	1	0
	Ciprofloxacin	4	2	29	1	7	0	0	0
	Gentamycin	0	6	5	0	3	0	0	0
	Tetracycline	4	9	22	1	15	0	0	0
	SXTa	1	9	14	1	6	0	0	0
Total colonies		20	33	29	1	15	1	8	14
Enterococci colonies isolated from mEnterococcus agar
Antibiotic supplement		Ampicillin		Tetracycline		None
Day		0	35	0	35	77
Resistance phenotype	Ampicillin	34		16	18
	Ciprofloxacin	29		27	36
	Erythromycin	26		22	31
	Tetracycline	12		31	40
	Vancomycin	15		13	21
Total colonies		39	0	31	40	0

^aTrimethoprim-sulfamethoxazole (SXT).