Abstract
Coagulase-negative staphylococci (CNS) are generally considered to be opportunistic pathogens. Controlling CNS mastitis is difficult because the epidemiology is not clear, and the CNS group consists of about 40 different Staphylococcus species. Therefore, the aim of this study was to determine the prevalence of coagulasenegative staphylococci in milk of the cows with subclinical mastitis, as well as to determine different CNS species isolated from quarter milk samples for their susceptibility to antimicrobials used commonly for mastitis therapy. On the farm where there was found an increase of somatic cells in bulk milk, 112 dairy cows were examined by mastitis test. From 52 udder quarters where mastitis test showed an increase of somatic cells, milk samples were taken for bacteriological examination. For isolating the causes of mastitis there was used blood agar. Identification of the causative agents of mastitis was carried out on the basis of colony appearance on blood agar and their physiological characteristics. Coagulasepositive staphylococci sensitivity which cause mastitis was tested by Kirby Bauer method. For susceptibility testing there were used commercially produced discs containing: 10 IU penicillin, amoxicillin/clavulanic acid (20 +10 ?g), cloxacillin 25 ?g, 30 ?g amoxicillin, cephalexin 30 ?g, ceftiofur 30 ?g, 15 ?g lincomycin, gentamicin and tetracycline 30 ?g. The sensitivity of microorganisms was evaluated on the basis of inhibition zone diameter recommended by the manufacturer and was labeled as sensitive (S) moderately sensitive (I) or resistant (R). Coagulase-negative staphylococci were isolated from 61.53% of samples from cows with subclinical mastitis, making them the most common cause of subclinical mastitis. The highest resistance of coagulase-negative staphylococci was found to penicillin G (58.33% of isolates). Full sensitivity of coagulase-negative staphylococci was found to amoxicillin / clavulanic acid (100% of isolates), a good sensitivity to ceftiofur (83.33% of isolates), cefalexin (70.83% of isolates) and ceftriaxone (41.66% of isolates).
Highlights
Koagulaza negativne stafilokoke se smatraju oportunisti~ki patogenim mikroorganizmima
Svi izolati koagulaza negativnih stafilokoka su bili osetljivi na amoksicilin/klavulansku kiselinu, 83,33% izolata je bilo osetljivo na ceftiofur, 70,83% izolata je bilo osetljivo na cefaleksin i 41,66% izolata je bilo osetljivo na ceftriakson
Ova grupa autora smatra da otpornost koagulaza negativnih stafilokoka, izolovanih u slu~ajevima subklini~kih i klini~kih mastitisa, zavisi od starostiivotinje i da je manja (26%) u slu~aju prvotelki, u odnosu na krave sa ve}im brojem laktacija (39%)
Summary
Koagulaza negativne stafilokoke se smatraju oportunisti~ki patogenim mikroorganizmima. 2007; Bal i sar., 2010; Pyörälä i Taponen, 2009) navodi porast prevalence koagulaza negativnih stafilokoka kao uzro~nika mastitisa i smanjenje njihove osetljivosti na antimikrobna sredstva, Koagulaza negativne stafilokoke u okolini predstavljaju zna~ajan rezervoar gena rezistencije na antimikrobna sredstva, {to je prema Rajala-[ulc i sar. Bakteriolo{kim ispitivanjem 52 uzorka mleka uzetih iz pojedinih ~etvrti vimena krava, u kojima je mastitis testom utvr|eno pove}anje broja somatskih }elija, naj~e{}e su kao uzro~nici mastitisa izolovani gram-pozitivni mikroorganizmi iz 37 (71,15%) uzoraka mleka, dok su gram-negativni mikroorganizmi izolovani iz samo dva (3,84%) uzorka mleka, a 13 (25%) ispitivanih ~etvrti je bilo bakteriolo{ki negativno. 2007; Bal i sar., 2010; Pyörälä i Taponen, 2009) navodi porast prevalence koagulaza negativnih stafilokoka, kao uzro~nika mastitisa, i smanjenje njihove osetljivosti na antimikrobna sredstva. Rezultati ispitivanja osetljivosti koagulaza negativnih stafilokoka na penicilinske preparate prikazani su u Tabeli 2
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