In vitro susceptibilities of Campylobacter-like organisms to twenty antimicrobial agents

Abstract

We determined MICs of 20 antimicrobial agents for 50 representative strains of four subgroups of Campylobacter-like organisms (CLOs) by agar dilution. Ampicillin, gentamicin, doxycycline, tetracycline, ceftriaxone, rifampin, spectinomycin, nalidixic acid, and chloramphenicol were active against all strains of CLOs. Most CLO strains (83%) were inhibited by 4 ,ug of sulfamethoxazole per ml and by 8 ,Ig of trimethoprim-sulfamethoxazole per ml. Of type 1 strains, 28% were resistant to 8 ,g of erythromycin per ml. In addition, cross resistance between erythromycin and clindamycin was always present. Type 1 strains exhibited a broad distribution of MICs of metronidazole and streptomycin, whereas all type 2 strains were uniformly susceptible to metronidazole and resistant to streptomycin. Unlike type 1 and 3 strains, type 2 CLOs were susceptible to cephalothin and penicillin G and highly resistant to streptomycin. The type 3 strain was uniquely resistait to cefazolin. The majority of strains were not inhibited by cefoperazone; and all were resistant to trimethoprim. In contrast to Campylobacterjejuni and Campylobacterfetus subsp. fetus, ail CLOs tested were susceptible to 0.5 ,ug of rifampin per ml.Increased awareness of the role of Campylobacter spp. in human disease and the development of improved selective media have resulted in recent isolation of several novel Campylobacter spp. from humans (7,8,10,13,14,(16)(17)(18). Among these, we isolated Campylobacter-like organisms (CLOs) from symptomatic and asymptomatic homosexual nmen being evaluated for enteritis, proctitis, and proctocolitis in a sexually transmitted diseases clinic. These organisms were isolated by using, a selective medium containing vancomycin, polymyxin B, trimethoprim, and amphotericin B supplemented with 10%o sheep blood (2) after incubation at 37°C in a microaerophilic environment. The classification of these CLOs within the genus Campylobacter and their phenotypic characterization into three subgroups were recently described by Fennell et al. (8). Further studies revealed four genetically distinct CLO subgroups (types 1A, 1B, 2, and 3), two of which (types 1A and 1B) were phenotypically identical (21a). The spectrum of diseases associated with CLO infection includes asymptomatic gastrointestinal colonization (17), proctocolitis (17)

Revision of Campylobacter, Helicobacter, and Wolinella Taxonomy: Emendation of Generic Descriptions and Proposal of Arcobacter gen. nov.

“…Susceptible to ampicillin, gentamicin, rifampin, and tetracycline; resistant to trimethoprim. Variable resistance to nalidixic acid and cephalothin (18,20). The G+C content of the DNA ranges from 35 to 44 mol%.…”

Helicobacter canis Bacteremia in a Patient with Fever of Unknown Origin

“…There are no guidelines from the Clinical and Laboratory Standards Institute for methods or breakpoints to assess antimicrobial susceptibility of H. canis. MICs of 20 antimicrobial agents for 43 and 6 isolates of Helicobacter cinaedi and Helicobacter fennelliae, respectively, were determined by Flores et al by agar dilution (18). Antibiotics that were active in vitro against all tested isolates were ampicillin, gentamicin, doxycycline, tetracycline, chloramphenicol, nalidixic acid, rifampin, and ceftriaxone.…”

Bacteremia due to Helicobacter cinaedi in Two Patients with Human Immunodeficinecy Virus Infection

“…Susceptibility testing of H cinaedi to a variety of antimicrobial agents suggests that isolates are generally susceptible to ampicillin, tetracycline, chloran1pheni-col, anunoglycosides and quinolones, although 28% of 43 isolates were found to be resistant to 8 µg/ mL erythromycin (14). Susceptibility testing for these slowgrowing organisms has not been standardized, and optimal therapy for H cinaedi infection has not been determined.…”