Table 2 - Frequency of transferable multiple antibiotic resistance amongst coliform bacteria isolated from a treated sewage effluent in Antofagasta, Chile

Table 2. Percentages of resistance to different antibiotics in coliform species isolated from raw and treated sewage from the Antofagasta sewage treatment plant.

Antimicrobial Drugs	*Escherichia coli*		Enterobacter spp		Klebsiella spp		Citrobacter spp		Serratia spp
Antimicrobial Drugs	Raw n=100	Treated n=46	Raw n=13	Treated n=10	Raw n=20	Treated n=29	Raw n=7	Treated n=6	Raw n=4	Treated n=7
Ampicillin	74	89*	85	90	90	96	86	100	75	100
Nalidixic acid	15	24	8	10	25	21	14	17	25	43
Cephradine	22	35*	54	80*	15	41	28	50	25	29
Chloramphenicol	43	50	15	30	30	45	71	67	50	71
Streptomycin	44	54	23	40	55	58	29	50	50	71
Gentamicin	4	15*	8	30	5	17	14	17	25	43
Kanamicin	17	26	15	20	15	31	14	17	25	43
Cotrimoxazole	65	78	15	20	70	79	71	67	75	71
Tetracycline	67	72	38	50	75	86	57	83	50	71

*The difference in proportions of the resistant coliform species between raw and treated sewage is significant for some species (P < 0,05).