Genotypic characterization of Escherichia coli O157:H7 strains that cause diarrhea and hemolytic uremic syndrome in Neuquén, Argentina.
Shiga toxin-producing Escherichia coli (STEC) are important food-borne pathogens associated with cases of diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS). E. coli O157:H7 is the dominant serotype in Argentina and also in Neuquén Province, in which HUS incidence is above the national average, with a maximum of 28.6 cases per 100,000 children less than 5 years old reported in 1998. The aim of this study was to characterize a collection of 70 STEC O157 strains isolated from patients with diarrhea and HUS treated in the province of Neuquén, Argentina, between 1998 and 2011. All strains harbored eae, ehxA, rfbO157, and fliCH7 genes, and stx2a/stx2c (78.7%) was the predominant genotype. A total of 64 (91.4%) STEC O157 strains belonged to the hypervirulent clade 8 tested using both 4 and 32 SNP typing schemes. The strains showed the highest values reported in the literature for 6 of the 7 virulence determinants described in the TW14359 O157 strain associated with the raw spinach outbreak in the U.S. in 2006. Clade 8 strains were strongly associated with two of them: ECSP_3286, factor encoding an outer membrane protein that facilitates the transport of the heme complex (P=0.001), and in particular extracellular factor ECSP_2870/2872, coding proteins related to adaptation to plant hosts (P=0.000004). The q933 allele, which has been related to high toxin production, was present in 97.1% of the strains studied for the anti-terminator Q gene. In summary, this study describes, for the first time in Argentina, the almost exclusive circulation of strains belonging to the hypervirulent clade 8, and also the presence of putative virulence factors in higher frequencies than those reported worldwide. These data may help to understand the causes of the particular epidemiological situation related to HUS in Neuquén Province.
Laboratorio Central, Subsecretaría de Salud de Neuquén, Gregorio Martínez 65, 8300 Neuquén, Argentina. Electronic address: luispianciola@yahoo.com.ar.
Luis
L
Pianciola
Servicio Fisiopatogenia, INEI-ANLIS "Dr. Carlos G. Malbrán", Av. Vélez Sarsfield 563, 1281 Buenos Aires, Argentina.
Isabel
I
Chinen
Laboratorio Central, Subsecretaría de Salud de Neuquén, Gregorio Martínez 65, 8300 Neuquén, Argentina.
Melina
M
Mazzeo
Servicio Fisiopatogenia, INEI-ANLIS "Dr. Carlos G. Malbrán", Av. Vélez Sarsfield 563, 1281 Buenos Aires, Argentina.
Elizabeth
E
Miliwebsky
Laboratorio de Microbiología, Hospital "Dr. Horacio Heller", Godoy y Lighuén, 8300 Neuquén, Argentina.
Gladys
G
González
Laboratorio Central, Subsecretaría de Salud de Neuquén, Gregorio Martínez 65, 8300 Neuquén, Argentina.
Constanza
C
Müller
Servicio Fisiopatogenia, INEI-ANLIS "Dr. Carlos G. Malbrán", Av. Vélez Sarsfield 563, 1281 Buenos Aires, Argentina.
Carolina
C
Carbonari
Laboratorio Central, Subsecretaría de Salud de Neuquén, Gregorio Martínez 65, 8300 Neuquén, Argentina.
Mariano
M
Navello
Laboratorio Central, Subsecretaría de Salud de Neuquén, Gregorio Martínez 65, 8300 Neuquén, Argentina.
Eugenia
E
Zitta
Servicio Fisiopatogenia, INEI-ANLIS "Dr. Carlos G. Malbrán", Av. Vélez Sarsfield 563, 1281 Buenos Aires, Argentina.
Marta
M
Rivas
D001118:Argentina / Q000453:epidemiology; D016000:Cluster Analysis; D003967:Diarrhea / Q000453:epidemiology / Q000382:microbiology*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology*; D019453:Escherichia coli O157 / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D029968:Escherichia coli Proteins / Q000235:genetics; D005517:Foodborne Diseases / Q000453:epidemiology / Q000382:microbiology*; D005838:Genotype; D006463:Hemolytic-Uremic Syndrome / Q000453:epidemiology / Q000382:microbiology*; D006801:Humans; D017720:Molecular Epidemiology; D058889:Molecular Typing; D037521:Virulence Factors / Q000235:genetics
D029968:Escherichia coli Proteins; D037521:Virulence Factors
Clades; E. coli; Hypervirulent; O157; stx2; stx2c