Diversity and biofilm-production ability among isolates of Escherichia coli phylogroup D belonging to ST69, ST393 and ST405 clonal groups
1 Departamento de Microbiologia, REQUIMTE, Faculdade Farmácia Universidade Porto, Rua Jorge Viterbo Ferreira n° 228, 4050–313 Porto, Porto, Portugal
2 Microbial Biofilm Laboratory (LABIM), IRCCS Fondazione Santa Lucia, Rome, Italy
3 Servicio de Microbiología and CIBER en Epidemiología y Salud Pública (CIBERESP), Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Hospital Universitario Ramón y Cajal, Madrid, Spain
BMC Microbiology 2013, 13:144 doi:10.1186/1471-2180-13-144Published: 21 June 2013
Phylogenetic group D Escherichia coli clones (ST69, ST393, ST405) are increasingly reported as multidrug resistant strains causing extra-intestinal infections. We aim to characterize inter- and intraclonal diversity of a broad sample (isolates from different geographic locations and origins with variable antibiotic resistance profiles, 1980-2010) and their ability to adhere and form biofilm by both a modified quantitative biofilm producing assay and Field Emission Scanning Electron Microscopy (FESEM).
High virulence scores were observed among ST69 (median 14/range 9–15) and ST393 (median 14/range 8–15) clones, particularly enriched in pap alleles, iha, kpsMTII-K5 and ompT, in contrast with ST405 (median 6/range 2–14) isolates, exhibiting frequently fyuA, malX and traT. All ST69 and ST393 and only two ST405 isolates were classified as ExPEC. Biofilm production was detected in two non-clinical ST69 and three ST393 isolates from different origins showing variable virulence profiles. Within each clonal group, and despite the high diversity of PFGE-types observed, isolates from different countries and recovered over large periods of time were clustered in a few groups sharing common virulence gene profiles among ST69 (n = 10 isolates) and ST393 (n = 9 isolates) (fimH-iha-iutA-kpsMTII-K5-(traT)-sat-(ompT)-papA-papEF-papGII-papC) or ST405 (n = 6 isolates) (fimH-traT-fyuA-malX).
This study highlights the circulation of highly transmissible ST69, ST393 and ST405 variants among different settings. Biofilm production seems not to be directly correlated with their epidemiological success.