S. Loncarevic et al., CHARACTERIZATION OF LISTERIA STRAINS ISOLATED FROM SOFT AND SEMI-SOFTCHEESES, Food microbiology (Print), 15(5), 1998, pp. 521-525
Two hundred strains of Listeria monoctyogenes previously isolated from
19 soft and semi-soft cheeses by enrichment were characterized by ser
otyping and pulsed-field gel electrophoresis (PFGE). Strains of serogr
oup 1/2 predominated, with 33.5% of all strains belonging to serovar 1
/2a, 58.5% to serovar 1/2b and 5% to serovar 1/2c. By using a PFGE met
hod, 16 different clonal types were obtained All 10 isolates oft. mono
cytogenes recovered from one white mould cheese were serovar 1/2a, but
displayed two different PFGE profiles. Another 10 L. monocytogenes is
olates from white mould cheese recovered after a 48-h enrichment broth
procedure revealed two clonal types, only one of which could be detec
ted after 5 additional days of incubation in the same enrichment broth
. Cross-contamination in dairy plants and/or retail stores may play an
important role in the incidence and diversify of L. monocytogenes clo
nal types recovered from soft and semi-soft cheeses. Therefore, if is
necessary to characterize several isolates from the same sample when c
onducting epidemiological investigations. (C) 1998 Academic Press.