Four main virotypes among extended-spectrum-β-lactamase-producing isolates of Escherichia coli O25b:H4-B2-ST131: bacterial, epidemiological, and clinical characteristics.

A total of 1,021 extended-spectrum-β-lactamase-producing Escherichia coli (ESBLEC) isolates obtained in 2006 during a Spanish national survey conducted in 44 hospitals were analyzed for the presence of the O25b:H4-B2-ST131 (sequence type 131) clonal group. Overall, 195 (19%) O25b-ST131 isolates were detected, with prevalence rates ranging from 0% to 52% per hospital. Molecular characterization of 130 representative O25b-ST131 isolates showed that 96 (74%) were positive for CTX-M-15, 15 (12%) for CTX-M-14, 9 (7%) for SHV-12, 6 (5%) for CTX-M-9, 5 (4%) for CTX-M-32, and 1 (0.7%) each for CTX-M-3 and the new ESBL enzyme CTX-M-103. The 130 O25b-ST131 isolates exhibited relatively high virulence scores (mean, 14.4 virulence genes). Although the virulence profiles of the O25b-ST131 isolates were fairly homogeneous, they could be classified into four main virotypes based on the presence or absence of four distinctive virulence genes: virotypes A (22%) (afa FM955459 positive, iroN negative, ibeA negative, sat positive or negative), B (31%) (afa FM955459 negative, iroN positive, ibeA negative, sat positive or negative), C (32%) (afa FM955459 negative, iroN negative, ibeA negative, sat positive), and D (13%) (afa FM955459 negative, iroN positive or negative, ibeA positive, sat positive or negative). The four virotypes were also identified in other countries, with virotype C being overrepresented internationally. Correspondingly, an analysis of XbaI macrorestriction profiles revealed four major clusters, which were largely virotype specific. Certain epidemiological and clinical features corresponded with the virotype. Statistically significant virotype-specific associations included, for virotype B, older age and a lower frequency of infection (versus colonization), for virotype C, a higher frequency of infection, and for virotype D, younger age and community-acquired infections. In isolates of the O25b:H4-B2-ST131 clonal group, these findings uniquely define four main virotypes, which are internationally distributed, correspond with pulsed-field gel electrophoresis (PFGE) profiles, and exhibit distinctive clinical-epidemiological associations.

Journal Article; Research Support, Non-U.S. Gov't;

A.M. acknowledges the Ramón y Cajal program from the Spanish Ministerio de Economía y Competitividad, Gobierno de España. R.M. acknowledges the grant of the Agencia Española de Cooperación Internacional (AECI) (Ministerio de Asuntos Exteriores y de Cooperación). This work was partially supported by the Red Española de Investigación en Patología Infecciosa (REIPI) (no. RD06/0008/1018-1016, RD12/0015) and grant no. PI09/01273, 070190, 10/02021, 10/01955, 10/00795, and PI11/ 01117 (Instituto de Salud Carlos III, Fondo de Investigación Sanitaria, Ministerio de Economía y Competitividad, Gobierno de España), CN2012/303 09TAL007261PR and 10MRU261023PR (Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia and the European Regional Development Fund [ERDF]), 0048/2008 and CTS-5259 (Junta de Andalucía), BFU2011-26608 (Spanish Ministry of Education), 282004/FP7- HEALTH.2011.2.3.1-2 (European VII Framework Program), and FEDERINNTERCONECTA-COLIVAC (CDTI, Ministerio de Economía y Competitividad, Gobierno de España; Consellería de Economía e Industria, Xunta de Galicia; ERDF). This material also is based partly upon work supported by the Office of Research and Development, Medical Research Service, Department of Veterans Affairs, grant no. 1 I01 CX000192 01.