Genotype diversity of brucellosis agents isolated from humans and animals in Greece based on whole-genome sequencing.

BACKGROUND: Brucellosis is a zoonotic disease whose causative agent, Brucella spp., is endemic in many countries of the Mediterranean basin, including Greece. Although the occurrence of brucellosis must be reported to the authorities, it is believed that the disease is under-reported in Greece, and knowledge about the genomic diversity of brucellae is lacking. METHODS: Thus, 44 Brucella isolates, primarily B. melitensis, collected between 1999 and 2009 from humans and small ruminants in Greece were subjected to whole genome sequencing using short-read technology. The raw reads and assembled genomes were used for in silico genotyping based on single nucleotide substitutions and alleles. Further, specific genomic regions encoding putative virulence genes were screened for characteristic nucleotide changes, which arose in different genotype lineages. RESULTS: In silico genotyping revealed that the isolates belonged to three of the known sublineages of the East Mediterranean genotype. In addition, a novel subgenotype was identified that was basal to the other East Mediterranean sublineages, comprising two Greek strains. The majority of the isolates can be assumed to be of endemic origin, as they were clustered with strains from the Western Balkans or Turkey, whereas one strain of human origin could be associated with travel to another endemic region, e.g. Portugal. Further, nucleotide substitutions in the housekeeping gene rpoB and virulence-associated genes were detected, which were characteristic of the different subgenotypes. One of the isolates originating from an aborted bovine foetus was identified as B. abortus vaccine strain RB51. CONCLUSION: The results demonstrate the existence of several distinct persistent Brucella sp. foci in Greece. To detect these and for tracing infection chains, extensive sampling initiatives are required.

Typing of Legionella strains isolated from environmental samples in Crete, Greece, during the period 2004-2011.

In Greece, standard tests are performed in watering and cooling systems of hotels. A total of 1,494 water samples were collected during 2004-2011 from 124 hotels from four regions in Crete (Greece). Samples were tested for the presence of Legionella spp.; 103 isolates were identified and typed by polymerase chain reaction (PCR)-sequencing and sequence-based typing (SBT) (in case of L. pneumophila sg 1). Of those, 48 belonged to various serogroups of L. pneumophila (sg 1, 2, 3, 5, 6, 8, 12, 13, and 15), 32 were characterized as L. anisa, 17 as L. taurinensis and there was a single occurrence of L. quinlivanii, L. maceachernii, and L. oakridgensis. In the case of L. pneumophila SG1, one prevalent sequence type was revealed (ST37). The variability of Legionella spp. observed questions the existence of a single ST of the L. pneumophila sg1 species and leads towards the need for a genetic level investigation of all Legionnaires' disease cases.