Journal Article

<i>In vitro</i> activities of spectinomycin and comparator agents against <i>Pasteurella multocida</i> and <i>Mannheimia haemolytica</i> from respiratory tract infections of cattle

Stefan Schwarz, Corinna Kehrenberg, Sarah A. Salmon and Jeffrey L. Watts

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 53, issue 2, pages 379-382
Published in print February 2004 | ISSN: 0305-7453
Published online February 2004 | e-ISSN: 1460-2091 | DOI:
In vitro activities of spectinomycin and comparator agents  against Pasteurella multocida and Mannheimia haemolytica  from respiratory tract infections of cattle

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Objectives: Prior to the renewal of spectinomycin licensing for veterinary uses in Germany, 154 Pasteurella multocida and 148 Mannheimia haemolytica strains from respiratory tract infections in cattle were investigated for their MICs of spectinomycin and other antimicrobial agents. The data obtained should serve as a baseline from which to judge the future development of resistance. Moreover, the in vitro activity of spectinomycin in comparison with other antimicrobials should be assessed.

Methods: MIC determination for all 302 strains was performed by the broth dilution method and evaluated according to NCCLS standards. MIC50 and MIC90 values were calculated. Strains resistant to spectinomycin were subjected to PCR assays for genes known to mediate spectinomycin resistance in Gram-negative and Gram-positive bacteria.

Results: With the exception of resistance to sulfamethoxazole in P. multocida and M. haemolytica, and resistance to ampicillin in M. haemolytica, an overall low level of resistance was detected. A total of 93.5% of the P. multocida and 98.6% of the M. haemolytica strains were susceptible to spectinomycin, with MIC90s of 32 mg/L. PCR analysis showed that none of the spectinomycin-resistant strains carried any of the aadA gene subtypes, nor the genes spc or aad(9).

Conclusions: Prior to the renewal of spectinomycin, only a small number of spectinomycin-resistant strains was detected among bovine P. multocida and M. haemolytica. The genes responsible for spectinomycin resistance in these strains seemed to be different from those so far known to occur in other Gram-negative and Gram-positive bacteria.

Keywords: Keywords: antibiotic resistance, aminocyclitol antibiotics, MIC determination, PCR analysis

Journal Article.  2173 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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