Table 5.

Average susceptibility of isolated E. coli stains to clindamycin (Cli) and oxytetracycline (Oct) in each production cycle in E. coli–vaccinated birds.

Farm	Week	Antimicrobial	Average susceptibility of E. coli isolates in vaccinated chicken houses in each cycle
			Cycle 1	Cycle 2	Cycle 3
F1	3	Cli	0	0	0
		Otc	0	0	1.33
	6	Cli	0	0	0
		Otc	0	1	0
F2	3	Cli	0	0	0
		Otc	0	0	0
	6	Cli	0	0.38	0
		Otc	0	0	0
F3	6	Cli	0	ND1	ND
		Otc	0	ND	ND

The results of E. coli vaccine strains revealed that average susceptibility of this strain to clindamycin (Cli) and oxytetracycline (Oct) was 3. Field E. coli isolates were not susceptible to both antimicrobials at any point of the experiment.

Abbreviation: E. coli, Escherichia coli.

¹Not done.