ABSTRACT
Objective To analyze the subtypes of eae genes in various non-O157 Shiga toxin-pro-ducing Escherichia coli ( STEC) strains isolated in China.Methods The complete nucleotide sequences of 10 eae genes were amplified by PCR and sequenced.The BLASTn software was used to analyze the se-quences for eae gene subtyping.A phylogenetic tree was constructed based on the10 ea e gene sequences to-gether with the gene sequences of 30 different subtypes in GenBank and those of STEC strains of 7 prevalent serotypes (O157 ∶H7, O26 ∶H11, O103 ∶H2, O111 ∶H8, O145 ∶H28, O45 ∶H2 and O121 ∶H19) using MEGA 5.0.Multilocus sequence typing (MLST) was performed on the 10 STEC strains with reference to the Escherichia coli ( E.coli) MLST website ( http://mlst.warwick.ac.uk/mlst/dbs/Ecoli) for the typing of multiple loci.A minimum spanning tree ( MST) was constructed using the BioNumerics software to inves-tigate the phylogenetic relationships between the 10 eae gene-positive STEC strains in this study and hemolyt-ic uremic syndrome-associated enterohemorrhagic E.coli ( HUSEC) strains as well as all human STEC strains of O157, O26, O45, O103, O111, O121 and O145 serotypes submitted to the E.coli MLST website data-base.Results The complete nucleotide sequences of eae genes in 10 non-O157 STEC strains were 2.8 kb in length and belonged to 3 known subtypes.The predominant subtype wasβ1, accounting for 60%of the 10 STEC strains (6/10), followed byθandγ1 subtypes with two strains in each type.The eae gene sequences in certain strains were identical to those of the prevalent serotypes.Seven sequence types ( STs) were identi-fied from the 10 STEC strains carrying eae gene.Conclusion The eae genes harbored by the non-O157 STEC strains isolated from different specimens in China were diverse and had close phylogenetic relationships with the highly pathogenic and prevalent STEC strains.This study implied that the STEC strains harboring eae gene had high pathogenic potential.
ABSTRACT
Mastitis has been recognized for some time as the most costly disease in dairy herds. From February to November 2004, 670 samples of bovine mastitic milk from which 231 Escherichia coli strains were isolated, were collected from two Brazilian states. The strains were screened for the presence of Shiga toxin-producing (stx 1 and stx 2) and intimin (eae) genes. Twenty (8.6 percent) strains were detected by PCR to harbor the Shiga toxin genes (8 the stx 1 gene, 12 the stx 2 gene and none both of them). Two (0.8 percent) of the Escherichia coli strains studied were eae positive non Shiga toxin-producing. The strains were also examined for resistance to 12 antimicrobial agents. The predominantly observed resistance was to tetracycline (92.2 percent), streptomycin (90.4 percent), nalidixic acid (88.3 percent), amikacin (86.5 percent) and cephalothin (84.8 percent). Multidrug resistance was found among 152 isolates (65.8 percent).
A um longo tempo a mastite tem sido reconhecida como a doença que provoca as maiores perdas econômicas nos rebanhos leiteiros. De fevereiro a novembro de 2004, foram coletadas 670 amostras de leite mastítico de vacas, provenientes de dois estados brasileiros, das quais foram isoladas 231 cepas de Escherichia coli. Estas cepas foram analisadas para a detecção dos genes de produção de Shiga toxina (stx 1 e stx 2) e do gene da intimina (eae). Vinte cepas (8,6 por cento) foram detectadas através de PCR como contendo os genes da Shiga toxina (8 stx 1, 12 stx 2 e nenhuma delas ambos os genes). Duas cepas (0,8 por cento) de E. coli eram eae positivo não produtoras de Shiga toxina. As cepas de E. coli foram também examinadas para detectar a resistência a 12 agentes antimicrobianos. As resistências mais freqüentes foram para tetraciclina (92,2 por cento), estreptomicina (90,4 por cento), ácido nalidixico (88,3 por cento), amicacina (86,5 por cento) e cefalotina (84,8 por cento). A resistência a múltiplas drogas foi encontrada em 152 cepas (65,8 por cento).
Subject(s)
Animals , Female , Shiga-Toxigenic Escherichia coli/isolation & purification , Drug Resistance, Multiple, Bacterial , Mastitis, Bovine , Polymerase Chain Reaction , CattleABSTRACT
Shiga toxigenic Escherichia coli (STEC) and Attaching and effacing E. coli (AEEC) have been associated with diarrhea illness in dogs. From January to December 2006, 92 E. coli isolates from 25 diarrheic dogs were analyzed, by screening for the presence of Shiga toxin-producing (stx 1 and stx 2) and intimin (eae) genes. Twelve isolates were detected by PCR to harbor the Shiga toxin genes (7 the stx 1 (7.6 percent); 5 the stx 2 (5.4 percent); and none both of them). Nine (9.8 percent) of the E. coli isolates studied were eae positive non Shiga toxin-producing. Thirteen (62.0 percent) isolates, carrying stx or eae gene, also showed a hemolysin production. The strains with virulence genes were also examined for resistance to 12 antimicrobial agents. Resistances to cephalothin (85.7 percent), streptomycin (81.0 percent), amoxicillin (71.4 percent) and gentamicin (71.4 percent) were predominantly observed.
Escherichia coli Shiga toxigênica (STEC) e E. coli Attaching- effacing (AEEC) têm sido associadas à doença diarréica em cachorros. Entre janeiro e dezembro de 2006, 92 cepas de E. coli isoladas de 25 cachorros diarréicos foram examinadas. As cepas foram analisadas para a detecção dos genes produtores de Shiga toxina (stx 1 e stx 2) e da intimina (eae). Por meio de PCR foi observado que sete cepas (7,6 por cento) portavam o gene stx 1, cinco cepas (5,4 por cento) carregavam o gene stx 2 e nenhum cepa apresentou ambos os genes associados. Nove cepas de E. coli (9,8 por cento) apresentaram o gene eae isoladamente. Treze das cepas (62,0 por cento) que apresentaram os genes stx ou eae também apresentaram a produção de a hemolisina. As cepas que apresentaram genes de virulência foram também examinadas em relação à resistência a 12 agentes antimicrobianos. As resistências mais comuns foram para cefalotina (85,7 por cento), estreptomicina (81,0 por cento), amoxicilina (71,4 por cento) e gentamicina (71,4 por cento).