Birgül KAÇMAZ, Teoman Zafer APAN, J. Sedef GÖÇMEN, Altan AKSOY, Murat YILDIRIM

Verotoxin production in strains of escherichia coli ısolated from cattle and sheep, and their resistance to antibiotics

Özet: Bu çalışmada, sığır ve koyun dışkısından izole edilen toplam 306 Escherichia coli susunun 10 antibiyotiğe direnç durumu ve bu suşlardan 130'unun verotoxin üretimi ve hemoliz özelliği araştırılmıştır. E. coli suşlarında tespit edilen antibiyotik direnç oranları sırasıyla; tetrasiklin % 51,6, streptomisin % 24,2, ampisilin % 13,1, amoksisilin-klavulanik asit % 5,2, gentamisin % 4,6, siprofloksasin % 4,6 ve trimetoprim-sulfametaksazol % 4,3, sefotaxim % 0,7 olup sefepim ve seftazidim'e dirençli suş saptanmamıştır. Test edilen antibiyotikler arasında sadece streptomisin direncinin sığır suşlarında koyun suşlarından yüksek olduğu tespit edilmiştir (P = 0,043). Sığır suşları cinsiyete ve yaşa göre değerlendirildiğinde dişi sığırlarda tetrasiklin ve streptomisin direncinin erkek sığırlara göre yüksek olduğu, ayrıca 2 yaş ve altındaki sığırlarda 3 yaşın üzerindeki sığırlara göre tetrasiklin direncinin anlamlı oranda yüksek olduğu görülmüştür. Sığırlardan izole edilen suşlardan dört tanesinin (% 2,2) VTEC O"157 serotipine ait olduğu, bu suşların test edilen antibiyotiklere duyarlı olduğu ve VTEC non-0157 serotipinin izolasyon oranının % 14,5 olduğu görüldü.E. colisuşlarında yerotoxin üretimi % 36,9 olup, koyun suşlannda bu oran % 61,1 ve sığır suşlarında % 19,7'dir. Koyunlardan izole edilen suşlarda verotoxin üretiminin sığırlardan izole edilen suşlardan anlamlı düzeyde yüksek olduğu görülmüştür (P < 0,001). Sığır suşlarında verotoxin üretimiyle antibiyotik direnci arasında bir ilişki tespit edilememiş olmasına rağmen koyun suşlannda ampisilin ve streptomisin direnci verotoxin salgılamayan suşlarda verotoxin salgılayan suşlara göre yüksek bulunmuştur (sırasıyla P = 0,048 ve P = 0,009). . E. co//suşlannda en sık rastlanan .hemoliz tipinin gamma hemoliz (% 46,2) olduğu, ampisilin ve amoksisilin-klavulanik asit direncinin hemoliz oluşturan suşlarda hemoliz oluşturmayan suşlardan anlamlı oranda yüksek olduğu tespit edilmiştir. Sonuç olarak, verotoxin salgılayan E. coli suşları açısından koyunların sığırlara göre daha fazla risk teşkil ettiği ayrıca insan enfeksiyonlarının tedavisinde de kullanılan tetrasiklin ve streptomisin gibi antibiyotiklere direnç oranlarının yüksek düzeyde bulunduğu ve bu direncin özellikle verotoksijenik türlerde de yüksek düzeyde bulunması antibiyotik seçiminde daha titiz davranılması gereğini ortaya koymuştur.

Sığır ve koyunlardan izole edilen escherichia coli suşlarında verotoxin üretimi ve antibiyotiklerde direnç durumu

Abstract: In this study, 130 Escherichia coli strains isolated from 306 cattle and sheep fecal samples were studied for their resistance to 10 antibiotics, verotoxin production, and hemolyzation. The antibiotic resistance rates of the E. coli strains were as follows: tetracycline, 51.6%; streptomycin, 24.2%; ampicillin, 13.1%; amoxicillin/clavulanic acid, 5.2%; gentamycin, 4.6%; ciprofloxacin, 4.6%; trimethoprim-sulfamethoxazole, 4.3%; cefotaxime, 0.7%. None of the strains were resistant to cefepime or ceftazidime. Of all the antibiotics tested, only resistance to streptomycin was higher in the strains isolated from cattle than in the sheep strains (P = 0.043). The evaluation of the cattle strains, based on gender and age, indicated that the resistance to tetracycline and streptomycin was higher in the female cattle than in male cattle, whereas in cattle under 2 years of age resistance to tetracycline was significantly higher than in 3-year-old cattle. Among the cattle strains there were 4 (2.2%) of the VTEC 0157 serotype. All were sensitive to the antibiotics tested, and the isolation rate of VTEC non-0157 serotypes was 14.5%. The overall verotoxin production rate of the E. constrains was 36.9%, while it was 61.1% in sheep strains and 19.7% in cattle strains. Verotoxin production in sheep strains was significantly higher than in cattle strains (P < 0.001). No correlation was detected between verotoxin production in the cattle strains and antibiotic resistance; however, resistance to ampicillin and streptomycin in the sheep strains that did not produce verotoxin was higher than that observed in the sheep strains that did (P = 0.048 and P = 0.009, respectively). The most common hemolysis type in the isolated E. coli strains was gamma hemolysis (46.2%). Ampicillin and amoxicillin/clavulanic acid resistance was significantly higher in the strains that hemolyzed than in the strains that did not. . In conclusion, sheep carry higher risks of verotoxin produced by E. coli strains than cattle do. Furthermore, due to higher resistance rates to such antibiotics as tetracycline and streptomycin, careful antibiotic selection for infections, particularly those caused by verotoxigenic E. coli, is of extreme importance.

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