title: Emergence of Ciprofloxacin-Resistant Salmonella enterica Serovar Typhi in Italy.
abstract: In developed countries, typhoid fever is often associated with persons who travel to endemic areas or immigrate from them. Typhoid fever is a systemic infection caused by Salmonella enterica serovar Typhi. Because of the emergence of antimicrobial resistance to standard first-line drugs, fluoroquinolones are the drugs of choice. Resistance to ciprofloxacin by this Salmonella serovar represents an emerging public health issue. Two S. enterica ser. Typhi strains resistant to ciprofloxacin (CIP) were reported to the Italian surveillance system for foodborne and waterborne diseases (EnterNet-Italia) in 2013. The strains were isolated from two Italian tourists upon their arrival from India. A retrospective analysis of 17 other S. enterica ser. Typhi strains isolated in Italy during 2011-2013 was performed to determine their resistance to CIP. For this purpose, we assayed for susceptibility to antimicrobial agents and conducted PCR and nucleotide sequence analyses. Moreover, all strains were typed using pulsed-field gel electrophoresis to evaluate possible clonal relationships. Sixty-eight percent of the S. enterica ser. Typhi strains were resistant to CIP (MICs, 0.125-16 mg/L), and all isolates were negative for determinants of plasmid-mediated quinolone resistance. Analysis of sequences encoding DNA gyrase and topoisomerase IV subunits revealed mutations in gyrA, gyrB, and parC. Thirteen different clonal groups were detected, and the two CIP-resistant strains isolated from the individuals who visited India exhibited the same PFGE pattern. Because of these findings, the emergence of CIP-resistant S. enterica ser. Typhi isolates in Italy deserves attention, and monitoring antibiotic susceptibility is important for efficiently managing cases of typhoid fever.
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Aurora
authors.initials: A
authors.lastname: García-Fernández
authors.affiliation: Regional Reference Centre for Salmonella serotyping, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Gallina
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Slawomir
authors.initials: S
authors.lastname: Owczarek
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Dionisi
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Ildo
authors.initials: I
authors.lastname: Benedetti
authors.affiliation: Food Hygiene and Safety Department, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Turin, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Decastelli
authors.affiliation: Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Ida
authors.initials: I
authors.lastname: Luzzi
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002939:Ciprofloxacin / Q000494:pharmacology*; D027081:DNA Gyrase / Q000235:genetics; D027101:DNA Topoisomerase IV / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D024841:Fluoroquinolones / Q000494:pharmacology; D007558:Italy; D008826:Microbial Sensitivity Tests; D016133:Polymerase Chain Reaction; D012485:Salmonella typhi / Q000187:drug effects* / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D024841:Fluoroquinolones; D002939:Ciprofloxacin; D027101:DNA Topoisomerase IV; D027081:DNA Gyrase