Aktuelle Daten zur Antibiotikaresistenz der wichtigsten bovinen Mastitiserreger in der Schweiz

Abstract

100 strains of Staphylococcus aureus (S. aureus), 100 strains of coagulase-negative staphylococci (CNS), 100 strains of Streptococcus spp. and 100 strains of Escherichia coli (E. coli), isolated from bovine mastitis milk samples between November 2002 and April 2003, were tested for their sensitivity to various antibiotics by means of the agar diffusion method. The antibiotics were chosen on the basis of their licenses for intramammary application in Switzerland (www.vetpharm.unizh.ch). 91% of the S. aureus strains were sensitive to all the antibiotics tested. Only 9% of the strains were resistant to Penicillin G and 7% to Ampicillin. 53% of the CNS strains were sensitive to all the antibiotics tested. 31% exhibited resistance to Penicillin G, 26% to Ampicillin, 16% to Cloxacillin and 14% to Lincomycin. 30% of the Streptococcus spp. strains were sensitive to all the antibiotics tested. 4% were resistant to Penicillin G, 4% to Amoxicillin/clavulanic acid, 1% to Cefoperazone, 2% to Cefquinome, 35% to Neomycin, 22% to Gentamicin, 61% to Kanamy-cin and 11% to Lincomycin. 43% of the strains showed multiple resistance. 79% of the E. coli strains were sensitive to all the antibiotics tested. 20% exhibited resistance to Ampicillin, 9% to Neomycin and 10% to Kanamycin. A comparison of the own results with data of other authors in Switzerland shows no important changes in the resistance situation during the last 20 years. With the exception of two strains (Streptococcus spp.), all tested isolates were sensible against Cefquinome.

Comparison of Antibiotic Resistance of Udder Pathogens in Dairy Cows Kept on Organic and on Conventional Farms

“…Nonaureus staphylococci had a higher percentage of antibiotic resistance than Staphylococcus aureus, which was in agreement with previously reported data of Corti et al (2003). The number of nonaureus staphylococci that showed resistance to at least one antibiotic was higher than that described by Rajala-Schultz et al (2004).…”

“…De Oliveira et al (2000) found only a low level of antibiotic resistance of bovine mastitis pathogens from Europe and the United States. In Switzerland, there was no increase of antibiotic resistance of mastitis pathogens during the last 20 yr (Corti et al, 2003). A recent review found no evidence that antibiotic therapy has led to a problem of resistance in mastitis-causing bacteria (NMC, 2004).…”

Antimicrobial susceptibility of mastitis pathogens of dairy cows in Switzerland

“…Although coliform pathogens had good overall susceptibility to gentamicin, cefoperazone and amoxicillin clavulanic acid ranging from 83.3 to 90.3 %, a considerable proportion of the isolates were resistant. This signals a change from earlier studies in which all investigated coliforms were sensitive to these drugs (Corti et al, 2003) or resistances were seen in less than 3 % of isolates (Moser et al, 2013). The susceptibility prevalences calculated in this study were subject to a selection bias and are not in consistence with a recently published study (Moser et al, 2013).…”

“…This was surprising because ten years earlier, the prevalence of penicillin-resistant Staph. aureus isolates was only 9 % in Switzerland (Corti et al, 2003), and 16.4 % (Overesch et al, 2013) and 20 % (Kretzschmar et al, 2013) in more recent studies. The prevalence of penicillin-resistant Staphylococcus spp.…”

“…The prevalence of penicillin-resistant Staphylococcus spp. was 31 % (Corti et al, 2003), 38 % (Kretzschmar et al, 2013), and 23.3 % (Frey et al, 2013). However, because of methodological differences in resistance testing, direct comparison of these studies is diffi cult.…”