title: Nosocomial outbreak caused by Salmonella enterica serotype Livingstone producing CTX-M-27 extended-spectrum beta-lactamase in a neonatal unit in Sousse, Tunisia.
abstract: In this study, we report an outbreak of Salmonella enterica serotype Livingstone resistant to extended-spectrum cephalosporins that occurred in a neonatal ward of the maternity department of Farhat Hached Hospital, Sousse, Tunisia, in 2002. A total of 16 isolates were recovered from 16 babies hospitalized in the ward during the period 1 to 16 July. All these babies developed diarrhea, and three of them developed septicemia. All the isolates demonstrated resistance to ceftriaxone and ceftazidime due to the production of an extended-spectrum beta-lactamase (ESBL). The isolates were also resistant to aminoglycosides (kanamycin, tobramycin, netilmicin, gentamicin, and amikacin) and sulfamethoxazole-trimethoprim. DNA profiles were determined by pulsed-field gel electrophoresis using the XbaI and SpeI endonucleases and by ribotyping with PstI digestion. They yielded the same patterns, showing that the outbreak was caused by a single clone. The ESBL was identified as CTX-M-27 by sequencing of PCR products and by isoelectric focusing. The ESBL resistance was transferred by a 40-kb conjugative plasmid. The mobile insertion sequence ISEcp1 was found to be located upstream of bla(CTX-M-27) in the same position as that known for a bla(CTX-M-14) sequence. A new gene named dfrA21, encoding resistance to trimethoprim and carried by a 90-kb plasmid, was characterized. The dfrA21 gene was inserted as a single resistance cassette in a class I integron. The babies were treated with colistin, and all except two recovered. The outbreak came to an end when appropriate actions were taken: patient isolation, hand washing, and disinfection of the ward.
authors.affiliation: Centre National de Référence des Salmonella, Unité de Biodiversité des Bactéries Pathogènes Emergentes, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris cedex 15, France.
authors.forename: Olfa
authors.initials: O
authors.lastname: Bouallègue-Godet
authors.forename: Youssef
authors.initials: Y
authors.lastname: Ben Salem
authors.forename: Laëtitia
authors.initials: L
authors.lastname: Fabre
authors.forename: Marie
authors.initials: M
authors.lastname: Demartin
authors.forename: Patrick A D
authors.initials: PA
authors.lastname: Grimont
authors.forename: Ridha
authors.initials: R
authors.lastname: Mzoughi
authors.forename: François-Xavier
authors.initials: FX
authors.lastname: Weill
mesh_terms: D000595:Amino Acid Sequence; D003227:Conjugation, Genetic; D003428:Cross Infection / Q000209:etiology*; D004196:Disease Outbreaks; D024881:Drug Resistance, Bacterial / Q000235:genetics; D006801:Humans; D007231:Infant, Newborn; D032023:Integrons; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D012480:Salmonella Infections / Q000209:etiology*; D019779:Salmonella enterica / Q000145:classification / Q000187:drug effects / Q000201:enzymology / Q000302:isolation & purification*; D014416:Tunisia / Q000453:epidemiology; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D001618:beta-Lactamases