Antimicrobial susceptibility of Campylobacter jejuni with special reference to resistance patterns of Canadian isolates

Abstract

Agar dilution antimicrobial susceptibility testing of Camphylobacter jejuni showed that erythromycin, clindamycin, nitrofurantoin, and gentamicin were the most active compounds, inhibiting 90% of the isolates at a concentration of 1 ,tg/ ml or less. The frequency of high-level erythromycin resistance was 1%. Erythromycin-resistant isolates showed cross-resistance to clindamycin. All strains were inhibited by chloramphenicol at -8,ig/ml. About 20% of the isolates were resistant to tetracycline at 4 ,ug/ml. All strains were highly resistant to novobiocin, bacitracin, vancomycin, and trimethoprim and resistant to rifampin. The minrimal inhibitory concentrations (MICs) of metronidazole ranged from _0.5 to 128 ,g/ ml. The susceptibility of strains to sulfamethoxazole and polymyxin B sulfate was markedly influenced by inoculum size. The MICs of polymyxin B sulfate were significantly higher at 42 than 36°C. All strains were inhibited by nalidixic acid at 32 ,Ag/ml. In the penicillin group, ampicillin was the most active compound, inhibiting only about three-quarters of the strains at 8 ,ug/ml. The cephalosporins as a group showed only moderate to poor activity, the most active cephalosporin being cefotaxime, which inhibited about 90% of the strains at 8 ,ug/ml. The use of antibiotics in selective media is discussed.

Improvement of Modified Charcoal-Cefoperazone-Deoxycholate Agar by Supplementation with a High Concentration of Polymyxin B for Detection of Campylobacter jejuni and C. coli in Chicken Carcass Rinses

“…We used a twotimes-higher concentration of polymyxin B (100,00 IU/liter) than that suggested by Karmali et al (8,9), but our results indicate that the addition of polymyxin B to mCCDA at this concentration does not inhibit the growth of either the C. jejuni or the C. coli strains tested in this study.…”

“…The antibiotic is bactericidal for Gram-negative bacteria, and its mode of action comprises two major steps, permeabilization of the outer membrane and induction of lethal leakage of cytoplasmic components (16). Although Karmali et al (8,9) reported that a high concentration of polymyxin B (50,000 IU/liter) improved the selectivity of media for the primary isolation of Campylobacter jejuni, the agent has not been used at high concentrations in recent times because Campylobacter coli was found to be highly susceptible when the agent was added to media such as Mueller-Hinton (MH) agar and Preston enrichment media (5,7,11). Polymyxin B has not been used at high concentrations in selective media containing a combination of cefoperazone and activated charcoal, such as mCCDA.…”

“…Interestingly, upon the addition of polymyxin B, the growth of most C. coli strains tested in this study (n ϭ 88) was greatly inhibited on bloodsupplemented MH agar (85 strains), Preston agar (85 strains), and Campy-Cefex agar (78 strains), but not on mCCDA. The inhibitory effect of antibiotic agents might differ because of various factors, such as growth temperature, growth condition, antibiotic combination, and toxin-neutralizing supplements (9,11). Activated charcoal and cefoperazone in mCCDA may harmonize with polymyxin B, reducing the inhibitory effect on C. coli; however, the underlying mechanism remains unclear.…”

In vitro susceptibilities of Campylobacter jejuni and Campylobacter coli to azithromycin and erythromycin

“…More recently, in the United States, 3% of C. jejuni strains were resistant to erythromycin, but a much greater incidence was noted among C. coli isolates, with 70% of isolates from hogs found to be resistant (13). Others have also noted a greater prevalence of erythromycin-resistant strains among C. coli than among C. jejuni isolates (3,6). In a recent Centers for Disease Control survey, 2.4% of Campylobacter strains were found to be resistant to erythromycin (10).…”

Characterization of erythromycin resistance in Campylobacter jejuni and Campylobacter coli

“…Erythromycin is the drug of choice for the treatment of serious cases of campylobacter gastroenteritis. The incidence of isolation of erythromycinresistant campylobacter strains ranges from less than 1% in Canada and the United Kingdom (9,22,41) to 8.4% in Belgium and 10% in Sweden (46,47). In the United States, Wang et al reported that 3% of campylobacter strains from human sources were resistant to erythromycin (48).…”