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Typing of Listeria monocytogenes strains isolated in Italy by inl A gene characterization and evaluation of a new cost‐effective approach to antisera selection for serotyping
Author(s) -
Tamburro M.,
Ripabelli G.,
Fanelli I.,
Maria Grasso G.,
Lucia Sammarco M.
Publication year - 2010
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/j.1365-2672.2009.04555.x
Subject(s) - serotype , listeria monocytogenes , typing , biology , multiplex polymerase chain reaction , lineage (genetic) , subtyping , antiserum , microbiology and biotechnology , polymerase chain reaction , virology , gene , bacteria , genetics , antigen , computer science , programming language
Aims: In this study, 105 Listeria monocytogenes strains isolated from humans, foods and environmental samples were characterized using several typing methods. Moreover, serotyping procedure was evaluated, and a cost‐effective methodological approach based on preliminary PCRs screening was proposed. Methods and Results: The isolates were analysed by conventional serotyping, multiplex‐PCRs for serogroup and lineage identification and PCR–RFLP of inl A gene to identify potentially noninvasive L. monocytogenes . Among the strains, only the serotypes 1/2a, 1/2c, 1/2b, 4b and 3a were identified. The isolates were classified into serogroups I (58·10%), II (22·85%), III (12·38%) and IV (6·67%). Among clinical strains, lineage I was more represented (68·75%) than lineage II; whereas, lineage II was more associated with food (90·24%) and environmental (85·72%) isolates. Most of food (89·02%) and environmental (85·71%) isolates were classified into truncated InlA profiles, whereas the 93·75% of clinical strains were associated with a complete form of the protein. Conclusion: Molecular techniques were sensitive and specific for classifying strains into serogroup and lineage and in agreement with the serotyping. Moreover, a preliminary PCRs‐based screening was proposed to select only the necessary antisera by a flow chart; this methodological approach allows cost saving up to 42%. Our results further suggest the role of InlA protein in human listeriosis, particularly in immunocompetent individuals, and a correlation between truncated protein and serotype. Significance and Impact of the Study: This study further validates molecular methods for L. monocytogenes analysis and proposed a new cost‐effective approach for serotyping. It could help to improve a national surveillance network for L. monocytogenes infections in Italy.