TABLE 1.

Resistance of C. jejuni subsp. jejuni to four antibiotics^a

Antimicrobial agent	Rate of resistance (%) of C. jejuni strains from the following time periodsb:
	1985–1986 (n = 47)	1992–1993 (n = 86)	1995–1997 (n = 158)
Erythromycin	0	0	0
Tetracycline	19.1	40.7c	55.7d
Nalidixic acid	0	4.7	13.9e
Ciprofloxacin	0	3.5	12.7f

^aOne strain from each patient was tested. 

^bThe resistance breakpoints are those of the National Committee for Clinical Laboratory Standards (11) for the agar dilution method: ≥8 μg/ml for erythromycin, ≥16 μg/ml for tetracycline, and ≥4 μg/ml for ciprofloxacin and nalidixic acid (see text). 

^cFor C. jejuni strains from 1992 and 1993 versus C. jejuni strains from 1985 and 1986, P = 0.01. 

^dFor C. jejuni strains from 1995 to 1997 versus C. jejuni strains from 1992 and 1993 (P = 0.03) and C. jejuni strains from 1985 and 1986, P = 0.03 and P < 0.001, respectively. 

^eFor C. jejuni strains from 1995 to 1997 versus C. jejuni strains from 1992 and 1993 and C. jejuni strains from 1985 and 1986, P = 0.02 and P = 0.007, respectively. 

^fFor C. jejuni strains from 1995 to 1997 versus C. jejuni strains from 1992 and 1993 and C. jejuni strains from 1985 and 1986, P = 0.02 and P = 0.009, respectively.