Characterisation of Listeria monocytogenes strains isolated from soft and semi-soft cheeses sampled in a region of Italy

Veterinaria Italiana

关键词: Antibiotic resistance;    Cheese;    Italy;    Listeria monocytogenes;    PFGE;    Pulsed-field gel electrophoresis;    Serotype.;   

DOI  :  

来源: DOAJ

【 摘 要 】

A total of 47 Listeria monocytogenes strains isolated in a survey of cheeses sampled from retail outlets were characterised. Five cheeses (Gorgonzola, Taleggio, Asiago, Crescenza and Brie) were chosen from the most popular soft and semi-soft cheeses consumed in Italy andmost commonly contaminated with L. monocytogenes. The serotype and antibiotic resistance pattern were determined for each strain and their macrorestriction profile was analysed with pulsed-field gel electrophoresis (PFGE). The main serotypes detected were 1/2a (76.6%) and 1/2c (21.3%). Serotype 1/2b was found in only one sample. A total of 97.9% of strains were resistant to oxacillin (OX), 80.9% to lincomycin (L) and 78.7% to clindamycin (CC). Of these strains, 17% were found to be resistant to two antibiotics (OX-CC or OX-L) while 70.2% were resistant to three antibiotics (OX-CC-L). No strains were susceptible to all the compounds tested. A combined analysis of the macrorestriction profiles AscI and ApaI identified eleven pulsotypes divided into three clusters. Two pulsotypes predominated, accounting for 57.4% and 21.3% of the isolated strains. Analysis of the PFGE profiles did not reveal any correlation between pulsotype and type of cheese, producer or retail outlet. A temporal analysis revealed that one pulsotype was persistent throughout the study period, with the exception of August and September, in which time a different pulsotype was detected. This variability suggests the influence of factors affecting the dynamics of the contamination of these products. Large-scale studies could help clarify this phenomenon.

【 授权许可】

Unknown