title: Mixed infection by Legionella pneumophila in outbreak patients.
abstract: During the molecular epidemiological study of a legionellosis outbreak, we obtained sequence based typing (SBT) profiles from uncultured respiratory samples of 15 affected patients. We detected several distinct allelic profiles some of which were a mixture of alleles present in the more common profiles. Chromatograms from the sequences of one patient with mixed profile showed polymorphisms in several positions, which could result from the simultaneous presence of different Legionella variants in the sample. In order to test this possibility, we cloned PCR amplification products from six loci for two patients with a mixed profile and a patient with a pure profile. After obtaining around 20 sequences for each locus of three patients, we detected several variants in two of them and two variants in the third one. In summary, the three analyzed patients showed evidence of more than one Legionella variant during the acute infection. These results indicate that probably some patients were infected by more than one strain, which could be due to co-infection from the same environmental source or, alternatively, to independent infections in a very short period of time. Although our data cannot discriminate between these hypotheses, these results suggest that Legionella infection patterns can be more complex than previously assumed. None of the environmental samples analyzed during this outbreak was even similar to any of the clinical ones.
authors.affiliation: Unidad Mixta Genómica y Salud, FISABIO-Salud Pública, Universidad de Valencia, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Valencia, Spain; CIBER en Epidemiología y Salud Pública (CIBERESP), Spain; Tuberculosis Research Unit, Swiss Tropical and Public Health Institute, Basel, Switzerland.
authors.forename: Mireia
authors.initials: M
authors.lastname: Coscollá
authors.affiliation: Centro de Salud Pública de Alzira, Conselleria de Sanitat, Valencia, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Fernández
authors.affiliation: Servicio de Microbiología, Hospital Universitario de La Ribera, Alzira, Valencia, Spain.
authors.forename: Javier
authors.initials: J
authors.lastname: Colomina
authors.affiliation: Unidad Mixta Genómica y Salud, FISABIO-Salud Pública, Universidad de Valencia, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Valencia, Spain; CIBER en Epidemiología y Salud Pública (CIBERESP), Spain.
authors.forename: Leonor
authors.initials: L
authors.lastname: Sánchez-Busó
authors.affiliation: Unidad Mixta Genómica y Salud, FISABIO-Salud Pública, Universidad de Valencia, Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Valencia, Spain; CIBER en Epidemiología y Salud Pública (CIBERESP), Spain. Electronic address: fernando.gonzalez@uv.es.
authors.forename: Fernando
authors.initials: F
authors.lastname: González-Candelas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D060085:Coinfection / Q000453:epidemiology* / Q000382:microbiology; D004196:Disease Outbreaks; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D016952:Legionella pneumophila / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D007877:Legionnaires' Disease / Q000453:epidemiology* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D058889:Molecular Typing; D017422:Sequence Analysis, DNA; D055815:Young Adult
keywords: Legionella pneumophila; Mixed infection; Outbreak; PCR products; Sequence-based typing; Uncultured samples