Additionally, it would explain why only a 3–30% of lactating women suffer from such infection when it is the predominant bacterial species found in breast milk of healthy women [29,30]. Conclusion Staphylococcus epidermidisis the most prevalent staphylococcal species isolated from breast milk of women suffering mastitis, where it is present at a concentration notably higher than that present in milk of healthy woman (≥ 4.0 versus ≤ 3.0 log10cfu mL-1, respectively). The percentage of strains showing biofilm production

ability and resitance to mupirocin, erythromycin, clindamicyn and/or methicillin was significantly SHP099 higher among those obtained from women with lactational mastitis than among those isolated from healthy Momelotinib purchase women. The random method used to select staphylococcal colonies from the samples could introduce a bias regarding the low number of samples from whichS. aureuswas isolated. Traditionally,S. aureushas been considered as the main etiological agent of mastitis. However, the results of this work suggest thatS. epidermidiscould be an additional and underrated cause of lactational mastitis; as a consequence, its presence should be also considered in bacteriological analyses of human milk when there is a suspicious

of a mastitis infection. Further studies involving a larger number of samples and staphylococcal isolates will be required to confirm the results obtained in this study. Methods Samples and isolation of staphylococcal isolates A total of 30 women aged 25–34 years with clinical symptoms of infectious mastitis participated in the study (Table1). They were diagnosed Phospholipase D1 by the lactation consultants attending different primary health-care centers in Spain in a 2-months period (October-November 2007). The total staphylococcal count was higher ≥ 4 log10cfu mL-1in all their samples. Women with mammary abscesses or any kind of parallel diseases and patients treated with antibiotherapy during the previous two weeks of the study were excluded.

All volunteers gave written informed consent to the protocol, which was approved by the Ethical Committee of Hospital Clínico of Madrid (Spain). The milk samples were collected as described previously [31], and plated onto ready to use Baird Parker (BP) plates supplied by bioMérieux (Marcy l’Etoile, France). The plates were incubated in aerobiosis at 37°C for 48 h. Identification of staphylococci Initially, a total of 270 isolates (10 from each sample displaying bacterial Selleckchem EPZ015938 growth on BP plates) were randomly selected and tested for catalase and coagulase activities and for their resistance to lysozyme and lysostaphin [32]. All of them were subjected to a novel multiplex PCR method designed to allow a rapid identification ofS. epidermidisandS. aureusisolates. The new primers (see below) were designed on the basis of the variable regions of thetufgene sequence ofStaphylococcususing the program Clone Manager Suite 7.0 (Sci Ed Central, USA).