The susceptibility patterns of 480 isolates representing six recently defined species of coryneform bacteria (Corynebacterium amycolatum [n = 101], Corynebacterium auris [n = 48], Corynebacterium glucuronolyticum [n = 86], Brevibacterium casei [n = 50], Dermabacter hominis [n = 49], and Turicella otitidis [n = 146]) to 17 antimicrobial agents were determined by an agar dilution method. Most significantly, for C. amycolatum strains the MICs at which 90% of isolates are inhibited were > or = 32 micrograms/ml for nearly all agents. However, all 480 strains examined were susceptible to glycopeptide antibiotics.

The activities of BAL9141 (formerly Ro 63-9141), a novel pyrrolidinone-3-ylidenemethyl cephalosporin, against 244 strains of gram-negative nonfermenters were evaluated. The overall MIC at which 50% of isolates are inhibited (MIC 50 ) and the overall MIC 90 were 2 and 64 g/ml, respectively, which are similar to those of imipenem, lower than those of the other cephalosporins tested, amoxicillin, and the ticarcillin-clavulanic acid combination, and much higher than those of ciprofloxacin. BAL9141 shows species-dependent activity in vitro against a variety of gram-negative nonfermentative pathogens.BAL9141 (formerly Ro 63-9141) is a novel pyrrolidinone-3-ylidenemethyl cephalosporin that consistently has activity against methicillin-resistant strains of Staphylococcus spp. but that exhibits promising in vitro and in vivo activities against a variety of gram-negative pathogens (1). The purpose of this study was to evaluate the activity of BAL9141 against a broad range of aerobic gram-negative glucose-nonfermentative rods.(Part of this work was presented at the 38th Interscience Conference on Antimicrobial Agents and Chemotherapy, San Diego, Calif., 1998 [R. Zbinden, V. Puenter, and A. von Graevenitz, Abstr. 38th Intersci. Conf. Antimicrob. Agents Chemother., abstr. F-19, 1998].).The MICs of BAL9141 and nine other antimicrobials were determined by the NCCLS agar dilution method on non-cation-adjusted Mueller-Hinton agar (Becton Dickinson Microbiology Systems, Cockeysville, Md.) for 244 gram-negative nonfermenters that were collected through 1995 in the Department of Medical Microbiology, University of Zurich, Zurich, Switzerland, and a reference strain, Pseudomonas aeruginosa ATCC 27853 (5). A 0.5 McFarland suspension in phosphatebuffered saline was diluted 1/10 to obtain the desired inoculum of 10 7 CFU/ml. A multipoint inoculator was used to deliver 10 4 CFU per spot to each test plate and to control plates without antibiotics. Cultures were incubated at 35°C for 20 h in an aerobic atmosphere in accordance with the NCCLS methodology (5). BAL9141 of known potency was supplied by F. Hoffmann-La Roche, Basel, Switzerland (courtesy of P. Hebeisen). The other compounds were obtained from commercial sources. Identification of the isolates studied was in accordance with recommended methods (4). The MICs of BAL9141 and the other antimicrobial agents are shown in Table 1. The modal MIC of BAL9141 for P. aeruginosa ATCC 27853 was 2 g/ml; the MICs of the other antimicrobial agents for P. aeruginosa fell within expected ranges (6). The MICs at which 50% of isolates are inhibited (MIC 50 s) and MIC 90 s for all 244 strains were 2 and 64 g/ml, respectively, for BAL9141; 8 and 64 g/ml, respectively, for cefepime; 64 and Ͼ64 g/ml, respectively, for cefotetan; 8 and Ͼ64 g/ml, respectively, for cefozopran; 8 and Ͼ64 g/ml, respectively, for ceftazidime; 8 and Ͼ64 g/ml, respectively, for ceftriaxone; 32 and Ͼ64 g/ml, respectively, for amoxicillinclavulanic acid; 32 and Ͼ64 g/ml, respectively, for ticarcillinclavulanic acid; 1 and 64 g/m...

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The identification of 202 isolates of aerobically growing Gram‐positive rods from clinical material was attempted by using a combination of “traditional” morphological and biochemical tests (Hollis & Weaver (20)) plus patterns of cellular and metabolic fatty acids. This system served as the “gold standard” for three others, i.e. API Coryne (Rapid Coryne), MIDI TSBA and MIDI CLIN Aerobic. In addition, several growth, biochemical and susceptibility tests (growth on cystine‐tellurite blood agar, DNase, hippurate and starch hydrolysis, methanethiol formation, API ZYM, CAMP reaction, susceptibility to O/129 and to six antimicrobials) were done in order to check their usefulness for the identification of this group of bacteria. Our system, with the help of chemotaxonomic tests (m‐DAP and mycolic acids), was able to identify 154/202 (76%) of the isolates by species and an additional 41/202 (21%) by genus only; 7 (3%) could not be identified. The API Coryne system identified to species or genus level 140/195 isolates (72%). Corresponding figures for the MIDI TSBA and CLIN systems were 63/195 (32%) and 88/195 (45%); further details of species and genus identification are presented in the text. The main drawback of the commercial systems is the extent and probably the numerical depth of the data base. We recommend the use of our multisystem approach for the identification of Gram‐positive rods until commercial systems are based on a broader and numerically more extensive data base. The additional tests did not prove species‐ or genus‐specific.

OBJECTIVE: The susceptibilities to penicillin, tetracycline, erythromycin, gentamicin, vancomycin and teicoplanin of 58 strains of Corynebacterium jeikeium were assessed by disk diffusion and agar dilution reference methods. METHODS: Zone sizes and minimal inhibitory concentrations (MIC) by agar dilution were interpreted using the ranges in the NCCLS tables for organisms other than Haemophilus, Neisseria gonorrhoeae, and Streptococcus pneumoniae. RESULTS: By agar dilution, 14%, 88%, 17% and 26% of the 58 isolates were susceptible to penicillin, tetracycline, erythromycin, and gentamicin, respectively. Using the breakpoints for Listeria monocytogenes, all strains showed concordant results for penicillin by disk diffusion. Discrepancies in the interpretative categories by disk diffusion were found in four cases (two very major and two minor) for tetracycline, in nine (two very major, two major, and five minor) for erythromycin, and in 1 case (very major) for gentamicin. All 58 strains were susceptible to vancomycin and teicoplanin by agar dilution and disk diffusion. The overall agreement of interpretative disk diffusion for all six antibiotics was 95.9%. In addition, all strains were susceptible to both glycopeptides by E-test. However, for vancomycin the MIC results in 58.6% were two log2 dilutions and in 1.7% more than two log2 dilutions higher by E-test than by agar dilution, whereas for teicoplanin agreement within one log2 dilution was 100%. CONCLUSIONS: Further evaluation of methodologies of disk diffusion is required to obtain a better agreement for erythromycin and tetracycline. The criteria of the NCCLS for interpretation of disk diffusion are adequate for susceptibility testing of C. jeikeium to penicillin, gentamicin, vancomycin and teicoplanin.