## 4 Discussion
vulgare_ changes depending on the location; therefore, reports on medicinal effects might differ in each study. In comparison, _T. vulgare_ flower extracts had a lesser antibacterial effect than the essential oil obtained from it. The essential oil from _T. vulgare_ inhibited the growth of some Gram-positive bacteria such as _S. aureus_, _B. cereus_, _B. subtilis_, and _S. epidermidis_, and had no effect on Gram-negative bacteria. It is possible that the essential oil could be responsible for antibacterial effects in the extracts made from _T. vulgare_ flowers, or the yield of specific phenolic compounds was not substantial enough in the _T. vulgare_ extract. It was reported that the extract of _Tanacteum balsamita_, which contained twice the amount of flavonoids, had a better antibacterial effect [46]. When comparing the results of the antibacterial effects in our study, it should be noted that bovine mastitis isolates were used, but other research studies focused on human disease-causing bacterial isolates or reference strains. Along with our results, a study conducted in Romania found that herbal extracts had better inhibition of _S. aureus_ growth and a lower inhibition of _E. coli_, both isolated from bovine mastitistis [47]. Conversely, our study revealed that _T. vulgare_ extracts had some antibacterial effects against tested _Streptococcus_ strains and _Serratia liquefaciens_. Extracts from the flowers of _T. vulgare_ minimally inhibited the growth of _S. agalaciae_, but extracts from the leaves had minimal effects against _S. uberis_ and _Serratia liquefaciens_. When the same bacterial isolates of bovine mastitis were tested, 70% acetone extracts of _Quercus robur_ bark and 30% ethanol extracts of _Calluna vulgaris_ herb had broader antibacterial spectra and lower MIC and MBC [48]. One study reported that _Serratia liquefaciens_ was sensitive to ethanolic extracts of _Methula pulegium_, _Nepeta cararia_, _Melissa officinalis_, _Agastache foreticulum_, _Lavadula angustifolia_, _Origanum vulgare_, _Althaea officinalis_, _Plantago lanccolata_, _Artemisia abstitutium_, _Populus nigra_, and _Eerennia prunustri_, all of which contain both essential oil and phenolic compounds. The 80% ethanol extracts of _Senna macanthhera_, _Artemisia abstitutium_, _Cymbopogon nardus_, and _Baccharis dracuncullifolia_ showed promising antibacterial effect against _S. aureus_ strains isolated from bovine mastitistis [49]. _T. vulgare_ extracts were also effective against some resistant strains isolated from bovine mastitistis-infected udders. The sensitivity of the bacteria is shown in Figure 3. The 70% ethanol extracts of _T. vulgare_ flowers showed antibacterial activity against _S. aureus V256_, which is resistant to amoxicillin, ampicillin, erythromycinocin, novobiocin, and penicillin G. The 70% ethanol extracts of the leaves of _T. vulgare_ had weaker effects than the flower extracts against the same _S. aureus_ strain. The usual resistance cut-off point for penicillin is at a 26 mm inhibition zone diameter [30]. As _T. vulgare_ extracts measured 20-24 mm, they are considered weaker than penicillin [30]. The growth of _E. coli V4_ (resistant to amoxicillin, amoxicillinin/clavulanic acid, ampicillin, cephalexin, neomycin, penicillin) and _E. coli V252_ (resistant to amoxicillinin, amoxicillinin/clavulanic acid, cephalexin, erythromycincin, neomycin, novobiocin, penicillin) was inhibited by 70% ethanol extracts of _T. vulgare_ flowers. In this case, the necessary concentration was high and measured inhibition zones were low (8-10 mm). This is significantly lower than the breakpoint for standard treatments [30]. _S. uberis_ (resistant to amoxicillinin, gentamycin, neomycin, oxytetracycline, penicillin G, novobiocin) and _S. agalaciae_ (resistant to enrofloxacin, gentamycin, linomycin, oxytetracycline, penicillin G, trimethoprim/sulfamethoxazole), and _Serratia liquefaciens_ (resistant to amoxicillinin, ampicillin, erythromycinocin, nevobiocin, penicillin G) were sensitive to _T.