Characterization of A Staphylococcal Food Poisoning Outbreak in A Workplace Canteen during the Post-Earthquake Reconstruction of Central Italy
Fabrizia Guidi,
Anna Duranti,
Silvia Gallina,
Yacine Nia,
Annalisa Petruzzelli,
Angelo Romano,
Valeria Travaglini,
Alberto Olivastri,
Vincenzo Calvaresi,
Lucia Decastelli,
Giuliana Blasi
Affiliations
Fabrizia Guidi
Istituto Zooprofilattico Sperimentale Umbria e Marche “Togo Rosati”, via G. Salvemini 1, 06126 Perugia, Italy
Anna Duranti
Istituto Zooprofilattico Sperimentale Umbria e Marche “Togo Rosati”, via G. Salvemini 1, 06126 Perugia, Italy
Silvia Gallina
National Reference Laboratory for Coagulase Positive Staphylococci - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, via Bologna 148, 10154 Torino, Italy
Yacine Nia
European Union Reference Laboratory for Coagulase Positive Staphylococci - Laboratory for Food Safety, Anses, Université Paris-Est, F-94700 Maisons-Alfort, France
Annalisa Petruzzelli
Istituto Zooprofilattico Sperimentale Umbria e Marche “Togo Rosati”, via G. Salvemini 1, 06126 Perugia, Italy
Angelo Romano
National Reference Laboratory for Coagulase Positive Staphylococci - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, via Bologna 148, 10154 Torino, Italy
Valeria Travaglini
Presidio Ospedaliero C. e G. Mazzoni, Azienda Sanitaria Unica Regione Marche, Area Vasta n°5, via Degli Iris 1, 63100 Ascoli Piceno, Italy
Alberto Olivastri
Dipartimento di Prevenzione, Azienda Sanitaria Unica Regione Marche, Area Vasta n°5, Viale Marcello Federici, 63100 Ascoli Piceno, Italy
Vincenzo Calvaresi
Dipartimento di Prevenzione, Azienda Sanitaria Unica Regione Marche, Area Vasta n°5, Viale Marcello Federici, 63100 Ascoli Piceno, Italy
Lucia Decastelli
National Reference Laboratory for Coagulase Positive Staphylococci - Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d’Aosta, via Bologna 148, 10154 Torino, Italy
Giuliana Blasi
Istituto Zooprofilattico Sperimentale Umbria e Marche “Togo Rosati”, via G. Salvemini 1, 06126 Perugia, Italy
In summer 2017, a foodborne outbreak occurred in Central Italy, involving 26 workers employed in the post-earthquake reconstruction. After eating a meal provided by a catering service, they manifested gastrointestinal symptoms; 23 of them were hospitalized. The retrospective cohort study indicated the pasta salad as the most likely vehicle of poisoning. Foods, environmental samples, and food handlers’ nasal swabs were collected. Bacillus cereus (Bc) and coagulase-positive staphylococci (CPS) including S. aureus, together with their toxins, were the targets of the analysis. CPS, detected in all the leftovers, exceeded 105 CFU/g in the pasta salad, in which we found Staphylococcal Enterotoxins (SEs) (0.033 ng SEA/g; 0.052 ng SED/g). None of the environmental and human swabs showed contamination. We characterized 23 S. aureus from foods. They all belonged to the human biotype, showed the same toxigenic profile (sea, sed, sej, and ser genes), and had the same Pulsed Field Gel Electrophoresis (PFGE) pattern; none of them harbored mecA or mupA genes. We also detected Bc contamination in the pasta salad but none of the isolates harbored the ces gene for the emetic toxin cereulide. The EU Reference Laboratory for CPS confirmed the case as a strong-evidence outbreak caused by the ingestion of SEs produced by a single strain of S. aureus carried by the same human source. This outbreak was successfully investigated despite the emergency situation in which it occurred.
