title: Typing of Listeria monocytogenes strains isolated in Italy by inlA gene characterization and evaluation of a new cost-effective approach to antisera selection for serotyping.
abstract: OBJECTIVE
  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.
  
  
  RESULTS
  The isolates were analysed by conventional serotyping, multiplex-PCRs for serogroup and lineage identification and PCR-RFLP of inlA 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.
  
  
  CONCLUSIONS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Health Sciences, Faculty of Medicine and Surgery, University of Molise, Campobasso, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Tamburro
authors.forename: G
authors.initials: G
authors.lastname: Ripabelli
authors.forename: I
authors.initials: I
authors.lastname: Fanelli
authors.forename: G M
authors.initials: GM
authors.lastname: Grasso
authors.forename: G Maria
authors.initials: GM
authors.lastname: Grasso
authors.forename: M L
authors.initials: ML
authors.lastname: Sammarco
authors.forename: M Lucia
authors.initials: ML
authors.lastname: Sammarco
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D004783:Environmental Microbiology; D005516:Food Microbiology; D006801:Humans; D007106:Immune Sera / Q000378:metabolism; D007558:Italy; D008089:Listeria monocytogenes / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D008088:Listeriosis / Q000382:microbiology; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length; D012703:Serotyping / Q000191:economics* / Q000379:methods*
chemical_list: D001426:Bacterial Proteins; D007106:Immune Sera; C069761:internalin protein, Bacteria