The activity of 29 antimicrobial agents was tested against 95 strains of Campylobacter fetus subsp. jejuni isolated from human stools. Furazolidone and gentamycin were the most active agents. The tetracyclines, erythromycin, and chloramphenicol were very active against most of the strains, but with each antibiotic a few resistant strains were found. The penicillins were relatively inactive, and the cephalosporins tested were only active against occasional strains.The aims of this study were to determine the general susceptibility pattern of Campylobacter fetus subsp.jejuni; to recognize those antimicrobial agents to which it is generally susceptible and which might therefore be useful in the treatment of enteritis or septicemia due to Campylobacter; and to identify those antimicrobial agents to which it is always resistant and which might be used to develop an improved selective medium.In an early study of susceptibilities, Butzler et al. (4) showed that most strains of Campylobacter (Vibrio) fetus were resistant to the penicillins and almost all to cephalothin. We have now determined the in vitro activity of 29 antimicrobial agents against 95 strains isolated from patients' stools. MATERIALS AND METHODSBacterial strains. Ninety-five strains of C. fetus subsp. jejuni were used in this study. They were isolated from human stools in the laboratory of the Sint Pierre Hospital in 1976 and 1977 by means of the selective coproculture technique described by Butzler et al. (3), simplified by omitting the preliminary filtration of the stools (10). Strains were preserved as suspensions in fluid thioglycolate agar medium (Difco no. 0256-01) and stored in liquid nitrogen. When required, the suspensions were thawed and inoculated onto petri dishes containing fluid thioglycolate agar medium (Difco no. 0256-01) and stored in liquid nitrogen. When required, the suspensions were thawed and inoculated onto petri dishes containing fluid thioglycolate agar medium (Difco no. 0256-01) to which had been added 0.075% agar and 10% defibrinated sheep blood and, per milliliter, 25 IU of bacitracin (Nutritional Biochemicals Corp., Cleveland, Ohio), 0.005 mg of novobiocin (The Upjohn Co., Kalamazoo, Mich.), and 0.05 mg of actidione (Upjohn). The inoculated plates were incubated at 370C for at least 3 days in ordinary air with 10% CO2 added, since it had been found that subcultures of these organisms did not require any further reduction of the oxygen tension for growth. The carbon dioxide level was maintained by an automatic C02 controller (Portamatic, Forma Scientific Inc.). The colonies from the plates were then suspended in fluid thioglycolate medium and incubated for 24 h in 10% C02. Before the overnight cultures were used for inoculum, their turbidity was adjusted to match a McFarland no. 2 standard.Antibiotic susceptibility tests. The replica-inoculating apparatus described by Steers et al. (15) was used to apply the organisms to the surface of plates containing twofold dilutions of the antimicrobial agents. The medium used for sus...

The bacteriostatic and bactericidal activities of 24 antimicrobial agents were tested with the Dynatech MIC 2000 system against 86 strains of Campylobacter fetus subsp. jejuni from human sources. The penicillins (penicillin G, ampicillin, amoxycillin, carbenicillin) had poor activity. Ampicillin and amoxycillin were equally active. Cefotaxime revealed a rather good activity. Erythromycin, gentamicin, tobramycin, amikacin, and furazolidone were the most active compounds. Two strains (2.3%) were resistant to erythromycin. One strain (1.2%) was completely resistant to tobramycin. The tetracyclines (tetracyline, doxycycline, minocycline) were generally effective, but 8% of the strains were totally resistant to them. Minocycline was the most active. Chloramphenicol, thiamphenicol, and clindamycin had good activity. The bacteriostatic and bactericidal distributions for colistin, nalidixic acid, and metronidazole were broad.Since King (8) identified campylobacters as a possible cause of enteritis in humans, these microorganisms have become important pathogens, especially since 1972 when workers in Brussels (5) facilitated the isolation of the organisms by use of a selective technique. Since that time Campylobacter fetus subsp. jejuni (C. jejuni) became a frequently isolated enteropathogenic microorganism (2, 7, 13) with a worldwide distribution (6, 9, 12). It has also been associated with other pathologies (4,11,19).The seriously ill and septicemic patient should be treated, but until now there has been little information to guide the therapy. The aim of this study was to determine the in vitro activity of various antibiotics, as well as their degree of bactericidal action on campylobacters. MATERIALS AND METHODSBacterial strains. Eighty-six strains of C. jejuni isolated from human stools (5) were used in this study.

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SUMMARY The minimum inhibitory concentrations (MIC)