Correspondence

Department of Clinical Microbiology, Albert Szent-Gyirgyi Medical University, P.O. Box 482 6701 Szeged, Hungary

References Acar, J. F., Gutmann, L. & Kitzii, M. D. (1988). Beta-lactamases in dinimi isolates fpectrum implication of nilbactam/ampkallin. Drugs 35, Suppl. 7, 12-6. Arisawa, M. & Then, R. L. (1982). 6Acetylmethylenepenicillianic acid: a potent bctalactamase inhibitor. I. Inhibition of chromosomalry and R-factor-mediated betalactamasa. Journal of Antibiotics 35, 1578-83. Barry, A. L., Jones, R. N. and.the Collaborative Antimicrobial Susceptibility Testing Group (1988). Criteria for disc susceptibility tests and quality control guidelines for the cefoperazonesulbactam combination. Journal of Clinical Microbiology26, 13-7. Crosby, M. A. & Gump, D. W. (1982). Activity of cefoperazone and two beta-lactamase inhibitors, sulbactam and clavulanic acid against Bacteroides spp. correlated with beta-lactamase production.

Antimicrobial Agents and Chemotherapy 22, 398-^05. FaTimilly J. (1976). Susceptibility of Haemophiha inftuenzae to ampicillin as determined by use of modified, one minute beta-lactamase test. Antimicrobial Agents and Chemotherapy 9, 196-8. Jacobs, M. R., Aronoff, S. C , Johenning, S., Shlaes, D. M. & Yamabe, S. (1986). Comparative activities of the 0-lactamase inhibitors YTR 830, davulanate and sulbactam combined with ampicillin and broad-spectrum penicillins against defined beta-lactamase-producing aerobic Gramnegative bacilli. Antimicrobial Agents and Chemotherapy 29, 980-5. Jones, R. N., Wilson, H. W., Thomsberry, C. & Barry, A. L. (1985). In vitro antimicrobial activity of cefoperazone-sulbactam combinations against 554 clinical isolates including t review and betalactamase studies. Diagnostic Microbiology and Infectious Diseases 3, 489-99.

In-rHro activity of ten antibiotics against clinical isolates of Bacteroides urtofytiau Sir, Bacteroides weolyticus has been isolated increasingly from clinical specimens, especially from soft-tissue and genital infections (Duerden, Bennett & Faulkner, 1982; Eley, Garry & Bennett, 1989), including non-gonococcal urethritis (Fontaine et at., 1982). Since there have been few reports on the antimicrobial susceptibility of B. weolyticus isolated in the United Kingdom, we have evaluated the in-vitro activity of ten antibiotics against five NCTC strains and 49 distinct clinical isolates of B. weolyticus: 25 isolates from soft tissue infections and ulcers, including perineal, genital and peripheral ulcers, and 24 isolates from men with non-gonococcal, non-chlamydial urethritis. The strains were recently isolated from clinical specimens and identified as described previously (Eley et at., 1989). MIC determinations were made by an agar dilution method (Jones et al., 1985) using Brain Heart Infusion (BHI) agar supplemented with yeast extract (5 g/1), sodium formate (1 g/1), and sodium fumarate (15 g/1), and containing doubling dilutions of the different antibiotics. Test organisms were grown anaerobically for 72 h. Growth was harvested and suspended in supplemented BHI broth (as above) to match Wellcome opacity tube no. 1 at a concentration of 10*cfu/ml and diluted 1 in 100. A multipoint inoculator was used to deliver a 1 /d inoculum containing 104 cfu/spot. Plates were incubated at 36-5°C in an anaerobic cabinet and examined for the presence or

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K. aerogenes strains had a 0-lactamase resembling the SHV-type enzyme. It is well documented (Jacobs et al., 1986; Acar, Gutmann & Kitzis, 1988) that sulbactam is much less active than clavulanic acid against such /J-lactamases. In its combinations with ampicillin, ticarcillin, azlocillin, mezlociltin, piperaciUin and apalcillin, sulbactam caused practically no decrease in the MICs for the strains producing TEMtype and SHV-1-type /Mactamases (Jacobs et at., 1986). Combinations of these /J-lactams with clavulanic acid produced a four-fold or greater reduction in MIC. Arisawa & Then (1982) found that the concentrations of clavulanic acid required to reduce the activity of TEM-type /Mactamases by 50% are much less than the corresponding concentrations of sulbactam. Efforts were earlier made to combine cefoperazone with a fixed amount of sulbactam to extend its antibacterial activity against certain /Mactamase-producing Bacteroides spp. Using the MIC determination method, Crosby & Gump (1982) showed that the combination of cefoperazone with 2 mg/1 clavulanic acid caused a synergistic effect in 72-4% of the tested Bacteroides strains, whereas the combination of cefoperazone with 10 mg/1 sulbactam did so only in 65-5% of the strains. The results we report here support the earlier observations that sulbactam is less active than clavulanic acid against certain /?lactamases of the family Enterobacteriaceae. ELISABETH NAGY EDITH HAJDU J. FOLDES

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Table L Antimicrobial susceptibility of 49 clinical isolate* of B. weolyticus MICJK,

(mg/1)

(mg/1)

Range (mg/1)

ClirKJamycin Trospectomycin Benzylpenidllin Amoxicillin Augmentin Tetra cycline Minocydine Ciprofloxacin lmipenem Metronidazole

0-12 0-25

In-vitro activity of ten antibiotics against clinical isolates of Bacteroides ureolyticus.

Correspondence Department of Clinical Microbiology, Albert Szent-Gyirgyi Medical University, P.O. Box 482 6701 Szeged, Hungary References Acar, J. F...
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