Disk diffusion was a reliable, easy, and inexpensive method for testing the susceptibility of Campylobacter jejuni to erythromycin (215 susceptible and 45 resistant isolates) and to ciprofloxacin (154 susceptible, two intermediate, and 124 resistant isolates) using, respectively, an erythromycin disk and ciprofloxacin and nalidixic acid disks.Campylobacter jejuni subsp. jejuni (C. jejuni) is a major human pathogen responsible of 85 to 95% of enterocolitis caused by Campylobacter spp. These infections need to be treated with an antimicrobial agent in less than 50% of cases (1). Macrolides and fluoroquinolones are the first-and second-choice antimicrobial agents for that purpose (1,4,8,9,11,13). With the development of resistance of C. jejuni strains to both erythromycin and ciprofloxacin, routine susceptibility testing has become a very important tool for appropriate antimicrobial treatment when needed (4, 6-9, 11, 13). The main erythromycin resistance mechanism of C. jejuni strains (mutation of 23S ribosomal rRNA and proteins) confers a high-level resistance with MICs of Ն128 g/ml (9). The main quinolone resistance mechanism (mutation[s] of DNA gyrase A) can confer a low, intermediate, or high resistance level to ciprofloxacin and confers a high resistance level to nalidixic acid (4,14).Antimicrobial susceptibility testing of Campylobacter spp. with an agar dilution method has been standardized by the CLSI (2), and the erythromycin, ciprofloxacin, tetracycline, and doxycycline MIC interpretive criteria for C. jejuni and Campylobacter coli have been reported previously (3). The agar dilution method, however, is not convenient for testing a few isolates at a time, and the disk diffusion method has not been standardized yet.The aim of this study was to compare the results obtained by the disk diffusion method with those obtained with the reference agar dilution method to test the susceptibility of C. jejuni isolates to erythromycin and ciprofloxacin.

With disk diffusion, the following zone diameters are suggested to be resistant and susceptible breakpoints, respectively: for susceptibility testing of Campylobacter coli, no inhibition zone and 15 mm or more for erythromycin, and 20 mm or less and 25 mm or more for ciprofloxacin, in the absence or presence of an inhibition zone around the nalidixic acid disk; and for susceptibility testing of C. coli and Campylobacter jejuni, 20 mm or less and 26 mm or more for tetracycline.

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The susceptibility of 47 strains of Haemophilus ducreyi to amoxicillin, clavulanic acid, and the combination of both drugs was determined by agar dilution susceptibility testing. A synergistic antibacterial activity of the combination was found for β-lactamase-producing strains.

SUMMARY:An 8 year old boy developed cerebral abscess and purulent meningitis due to Clostridium perfringens and Clostridium paraputrificum after trauma to the left orbit. The patient made a satisfactory recovery with surgical treatment and antibiotic therapy. A review of the literature revealed that meningitis due to Clostridia is rare and usually related to penetrating trauma, and that penetrating trauma to the orbit is associated with significant central nervous system morbidity.