## 4 Discussion
Stressful situations, and particularly the acute ones, increase the SCC in healing and in infected mammary glands [48]. In our study most farms had livestock consisting of both ewes and goats. In sheep SCC are more valid as an index of subclinical or clinical mastitis than in goats [49] where often no significant differences are recorded between bacteriologically positive and bacteriologically negative udders [50; 51]. Differences in flock management as well as in the milking type, season (month, year), resistance to antibiotics and dry therapy can also affect the SCC and cause significant variations among flocks and within the same flock [52]. All these factors as well as breed, parity, estrus, and vaccination [53] can explain the differences reported in Table 1 and in Figure 1.  
It should be noted that the coefficient of variation of the average SCC values presented in Table 1 were low, ranging from 6.60% to 9.28% for group A and from 4.59% to 12.69% for group B. This finding in turn, indicates a low variation of the SCC among the bulk tanks every month. Furthermore, the average SCC values of group A are not significantly different from the ones of group B (Mann-Whitney U = 17, \(p\) = 0.93624). _S. aureus_ is classified among the most frequent bacterial causative agents of clinical mastitis in small ruminants [54; 55; 56; 57]. The isolation frequencies in the present study were low: two strains out of 120 samples in group A and six strains out of 120 samples in group B. This finding must be attributed to the effective use of antibiotics since all farmers are aware of the clinical manifestation of mastitis and most of them act immediately. The two strains isolated from group A had multi resistant profiles against seven substances, while the other six strains from group B had lower resistance profiles since one strain was sensitive to all substances, two strains to one substance, two strains in two substances and one strain to three substances. Ampicillin and tetracycline were the substances with increased recorded resistance (against seven and five strains, respectively). This is not a surprise because these two antibiotics are the commonly used in Greece. _E coli_ is a bacterium often associated with compromised hygiene of the milking process [58]. One strain was isolated from group B and 7 strains from group A out of 120 samples for every group. This low frequency implies that the hygiene of the milking process as well as the hygiene of the facilities, of the equipment, etc., are in a satisfactory level. Six of seven strains isolated from group A showed a multi resistant profile (three strains against seven substances, one strain against six substances, one strain against seven substances and one strain against three substances) while the sole strain isolated from group B was found multi resistant too. Ampicillin, Amoxicillin -clavulanic acid and tetracycline were the substances with the highest recorded resistance (seven, six and six strains, respectively) as in the case of _S. aureus_ and for the same reason. The two species were tested in different panel of antibiotics with only 6 common substances against which _E. coli_ strains expressed increased resistance with respect to those of _S aureus_, while all strains of both species were sensitive to ceftouf. A statistical correlation could not be established between the isolated strains resistance and other parameters such as season, SCC, or CNS counts. The reason for this can be attributed to the small size of the isolates. However, another possible explanation is that the resistance observed is a remainder of antibiotic abuse in the past. Even in the absence of disease (as the low SCC imply) the surviving strains carry the resistance conferred by past abuse or extensive use of antibiotics in previous years. The _S. aureus_ and _E. coli_ resistant isolates were relatively few and scarce since they were originating from different farms. Molecular methods such as sequencing, and genotyping could reveal the genetic determinants of this resistance [59; 60].