Biofilms of Enterococcus faecalis and Enterococcus faecium isolated from the processing of ricotta and the control of these pathogens through cleaning and sanitization procedures

The biofilm formation of Enterococcus faecalis and Enterococcus faecium isolated from the processing of ricotta on stainless steel coupons was evaluated, and the effect of cleaning and sanitization procedures in the control of these biofilms was determined. The formation of biofilms was observed while varying the incubation temperature (7,25 and 39 degrees C) and time (0, 1, 2, 4, 6 and 8 days). At 7 degrees C, the counts of E. faecalis and E. faecium were below 2 log(10) CFU/cm(2). For the temperatures of 25 and 39 degrees C, after 1 day, the counts of E. faecalis and E. faecium were 5.75 and 6.07 log(10) CFU/cm(2), respectively, which is characteristic of biofilm formation. The tested sanitation procedures a) acid-anionic tensioactive cleaning, b) anionic tensioactive cleaning + sanitizer and c) acid-anionic tensioactive cleaning + sanitizer were effective in removing the biofilms, reducing the counts to levels below 0.4 log(10) CFU/cm(2). The sanitizer biguanide was the least effective, and peracetic acid was the most effective. These studies revealed the ability of enterococci to form biofilms and the importance of the cleaning step and the type of sanitizer used in sanitation processes for the effective removal of biofilms. (C) 2015 Elsevier B.V. All rights reserved.