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1.
J Public Health (Oxf) ; 45(1): e30-e37, 2023 03 14.
Artigo em Inglês | MEDLINE | ID: mdl-34969078

RESUMO

BACKGROUND: Shiga toxin-producing Escherichia coli (STEC) are enteric pathogens that cause hemolytic-uremic syndrome (HUS). Ruminants, especially cattle, are their main reservoir. This study describes the seroepidemiology of STEC in rural and urban populations in Argentina, a country with a high HUS incidence. METHODS: A cross-sectional study was performed in patients without gastrointestinal symptoms. IgG antibodies against Stx2 were detected by western blotting. RESULTS: Anti-Stx2 antibodies were detected in 14.56% of serum samples, more frequently in rural (19.38%) than urban residents (12%). Seropositivity was associated with lower socioeconomic status (SES). Among the other variables considered, thawing homemade hamburgers before cooking them, and the lack of knowledge about HUS were also associated with seropositivity. A multivariate logistic regression analysis performed with the variables that were statistically significant showed that only the SES index remained significant. As SES was measured based on several variables, we further analyzed each one of them and found that the lack of a high education level was statistically associated with seropositivity. CONCLUSIONS: The present findings have implications for STEC prevention efforts, highlighting the importance of considering SES and risks factors linked to different SES levels when targeting consumer-level public health interventions.


Assuntos
Infecções por Escherichia coli , Síndrome Hemolítico-Urêmica , Escherichia coli Shiga Toxigênica , Bovinos , Animais , Toxina Shiga II , Argentina/epidemiologia , Estudos Transversais , Estudos Soroepidemiológicos , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/veterinária , Síndrome Hemolítico-Urêmica/diagnóstico , Síndrome Hemolítico-Urêmica/epidemiologia
2.
Rev Argent Microbiol ; 50(2): 147-150, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29066034

RESUMO

Two cross-sectional studies were carried out in 2013 and 2015 monitoring for Mycoplasma hyopneumoniae presence in a swine farm. In these studies, the genetic diversity of M. hyopneumoniae was assessed in clinical specimens using a Multiple Locus Variable-number tandem repeat Analysis (MLVA) targeting P97 R1, P146 R3 and H4 loci. The samples from August 2015 showed the MLVA profile prevalent in June 2013, therefore it can be concluded that a same genetic type of M. hyopneumoniae can persist for at least two years in a closed herd. In addition, the nested PCR reactions implemented in this study showed to be useful for MLVA typing in non-invasive clinical samples.


Assuntos
Mycoplasma hyopneumoniae , Pneumonia Suína Micoplasmática , Animais , Estudos Transversais , Variação Genética , Repetições Minissatélites , Mycoplasma hyopneumoniae/genética , Mycoplasma hyopneumoniae/isolamento & purificação , Pneumonia Suína Micoplasmática/genética , Suínos
3.
Rev Argent Microbiol ; 48(4): 325-328, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27667362

RESUMO

Shigatoxigenic Escherichia coli (STEC) is a foodborne pathogen that causes hemolytic uremic syndrome (HUS) and the consumption of chicken products has been related to some HUS cases. We performed a non-selective isolation and characterization of STEC strains from retail chicken products. STEC isolates were characterized according to the presence of stx1, stx2, eae, saa and ehxA; stx subtypes and serotypes. Most of them carried stx2, showing subtypes associated with severe human disease. Although reported in other avian species, the stx2f subtype was not detected. The isolates corresponded to different serotypes and some of them, such as O22:H8, O113:H21, O130:H11, O171:H2 and O178:H19, have also been identified among STEC isolated from patients suffering from diarrhea, hemorrhagic colitis, HUS, as well as from cattle. Considering the virulence profiles and serotypes identified, our results indicate that raw chicken products, especially hamburgers sold at butcheries, can be vehicles for high-risk STEC strains.


Assuntos
Microbiologia de Alimentos , Genes Bacterianos , Produtos Avícolas/microbiologia , Escherichia coli Shiga Toxigênica/isolamento & purificação , Animais , Argentina , Técnicas de Tipagem Bacteriana , Galinhas/microbiologia , Proteínas de Escherichia coli/genética , Sorotipagem , Escherichia coli Shiga Toxigênica/classificação , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/patogenicidade , Virulência
4.
Microbiology (Reading) ; 161(Pt 3): 451-62, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25479836

RESUMO

Shiga toxins are the main virulence factors of a group of Escherichia coli strains [Shiga toxin-producing E. coli (STEC)] that cause severe human diseases, such as haemorrhagic colitis and haemolytic-uraemic syndrome. The Shiga toxin family comprises several toxin subtypes, which have been differentially related to clinical manifestations. In addition, the phages that carry the Shiga toxin genes (stx phages) are also diverse. These phages play an important role not only in the dissemination of Shiga toxin genes and the emergence of new STEC strains, but also in the regulation of Shiga toxin production. Consequently, differences in stx phages may affect the dissemination of stx genes as well as the virulence of STEC strains. In addition to presenting an overview of Shiga toxins and stx phages, in this review we highlight current knowledge about the diversity of stx phages, with emphasis on its impact on STEC virulence. We consider that this diversity should be taken into account when developing STEC infection treatments and diagnostic approaches, and when conducting STEC control in reservoirs.


Assuntos
Bacteriófagos/metabolismo , Infecções por Escherichia coli/microbiologia , Toxinas Shiga/metabolismo , Escherichia coli Shiga Toxigênica/metabolismo , Escherichia coli Shiga Toxigênica/virologia , Animais , Bacteriófagos/genética , Humanos , Toxinas Shiga/toxicidade , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/patogenicidade , Virulência
5.
Rev Argent Microbiol ; 46(2): 122-5, 2014.
Artigo em Espanhol | MEDLINE | ID: mdl-25011596

RESUMO

In Argentina, EPEC is one of the most prevalent agents isolated from children with diarrhea. Because contamination with this pathotype could occur during slaughter, the aim of this study was to isolate and characterize EPEC strains obtained from live animals (cloacae), eviscerated carcasses, washed carcasses and water from chillers. Twenty nine isolates of atypical EPEC were characterized. These isolates presented a wide variety of serotypes, some of which (O2:H40, O8:H19 and O108:H9) had been reported in other animal species. Serotype O45:H8, previously isolated from children with diarrhea was also found. Isolates of serotypes O2:H40, O108:H9 and O123:H32 were detected at different stages of the slaughtering process, suggesting that the process is not adequately performed. This latter fact highlights the importance of reinforcing control and hygienic measures at different stages of the chicken slaughtering process in order to reduce microbial contamination.


Assuntos
Galinhas/microbiologia , Escherichia coli Enteropatogênica/isolamento & purificação , Matadouros , Animais
6.
Medicina (B Aires) ; 73(2): 127-35, 2013.
Artigo em Espanhol | MEDLINE | ID: mdl-23570760

RESUMO

The objectives of this study were (a) to describe and estimate the frequency of hemolytic uremic syndrome (HUS) in rural and urban populations in two regions of Buenos Aires Province, and (b) to compare the presentation and distribution of factors hypothetically associated with HUS. A total of 82 HUS cases, recorded during the years 2005-2010 in rural and urban areas of the south-central region of Buenos Aires Province, were clinically and epidemiologically characterized. Statistical data analysis included Chi square or Fisher test and median test. The incidence rate of HUS was significantly higher in the rural population, being 12.7 cases per 100 000 (CI 0-23.5) in rural inhabitants vs. 7.1 cases per 100 000 (CI 0-9.5) in urban inhabitants. The median age of the patients was 27 months (5-139 months), significantly lower in children from the rural area. This could be explained by a more frequent contact with bovine feces, the consumption of raw milk and a higher proportion of relatives who work in risk labors found in the rural population. Although HUS is often associated with the consumption of undercooked minced meat, most of the children cases here included did not present this antecedent. Clinical manifestations were similar in both subpopulations. One-third of urban patients had received antibiotics prior to HUS development.


Assuntos
Infecções por Escherichia coli/complicações , Escherichia coli/isolamento & purificação , Síndrome Hemolítico-Urêmica/epidemiologia , Animais , Argentina/epidemiologia , Bovinos , Criança , Pré-Escolar , Escherichia coli O157/isolamento & purificação , Fezes/microbiologia , Feminino , Manipulação de Alimentos , Higiene das Mãos , Síndrome Hemolítico-Urêmica/microbiologia , Humanos , Higiene , Incidência , Lactente , Masculino , Leite/microbiologia , Estudos Retrospectivos , População Rural , Fatores Socioeconômicos , População Urbana
7.
AIMS Microbiol ; 9(3): 570-590, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37649799

RESUMO

Shiga toxin-producing E. coli (STEC) are diarrheagenic strains that can cause bloody diarrhea and hemolytic-uremic syndrome. Their main virulence factor, the Shiga toxin (Stx), is encoded by phages integrated into the bacterial chromosome. Stx phages are widely diverse and carry many genes with limited or unknown function. As the toxin subtype Stx2a is associated with highly pathogenic strains, this study was mainly focused on the characterization of the stx flanking region of Stx2a phages. Of particular interest was a sialate O-acetylesterase (NanS-p), which has been described previously to be encoded downstream stx in some phage genomes and may confer a growth advantage for STEC. Complete DNA sequences of Stx2a phages and prophages were retrieved from the GenBank database, and the genomic regions from anti-terminator Q to holin S genes were bioinformatically analyzed. Predicted NanSp sequences from phages encoding other Stx subtypes were also studied. Additionally, expression of nanS-p was quantified by qPCR in strains selected from our laboratory collection. The analysis of Stx2a phage genomes showed that all carried the Q, stx2a, nanS-p and S genes, but with allele diversity and other sequence differences. In particular, sequence differences were detected in each of the three domains of NanS-p esterases encoded by Stx2a phages and other Stx phages; however, nanS-p was not identified in the Stx2e, Stx2f and Stx2g phages analyzed. The expression of nanS-p increased in most stx2a-positive strains under phage inducing conditions, as was previously shown for stx2a. As the present work showed diversity at the Q-S region among Stx phages, and particularly in the encoded NanS-p enzyme, future studies will be necessary to evaluate if NanS-p variants differ in their activity and to assess the impact of the absence of nanS-p in certain Stx phages.

8.
Curr Microbiol ; 65(3): 337-43, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22706777

RESUMO

Environmental samples were taken from ground, cattle water troughs, and feeders from a dairy farm with different STEC prevalence between animal categories (weaning calves, rearing calves, and dairy cows). Overall, 23 % of samples were positive for stx genes, stx(2) being the most prevalent type. Isolates were analyzed by PCR monoplex to confirm generic E. coli and by two multiplex PCR to investigate the presence of stx(1), stx(2), eae, saa, ehxA, and other putative virulence genes encoded in STEC plasmids: katP, espP, subA, and stcE. The toxin genes were subtyped and the strains were serotyped. The ground and the environment of the rearing calves were the sites with the highest number of STEC-positive samples; however, cattle water troughs and the environment of cows were the places with the greater chance of finding stx(2EDL933) which is a subtype associated with serious disease in humans. Several non-O157 STEC serotypes were detected. The serotypes O8:H19; O26:H11; O26:H-; O118:H2; O141:H-; and O145:H- have been asociated with human illness. Furthermore, the emergent pathogen STEC O157:H- (stx(1)-ehxA-eae) was detected in the environment of the weaning calves. These results emphasize the risk that represents the environment as source of STEC, a potential pathogen for human and suggest the importance of developing control methods designed to prevent contaminations of food products and transmission from animal to person.


Assuntos
Indústria de Laticínios , Microbiologia Ambiental , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/isolamento & purificação , Animais , Bovinos , Distribuição de Qui-Quadrado , Água Potável/virologia , Feminino , Esterco/virologia , Plasmídeos/genética , Toxinas Shiga/genética , Microbiologia do Solo
9.
Appl Environ Microbiol ; 77(1): 73-9, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21037301

RESUMO

In this study, we determined vt subtypes and evaluated verotoxicity in basal as well as induced conditions of verotoxin-producing Escherichia coli (VTEC) strains isolated from cattle and meat products. Most (87%) of the 186 isolates carried a vt(2) gene. Moreover, the vt(2) subtype, which is associated with serious disease, was present in 42% of our VTEC collection. The other vt subtypes detected were vt(1), vt(1d), vt(2vha), vt(2vhb), vt(2O118), vt(2d) (mucus activatable), and vt(2g). A total of 41 (22%) of the isolates possessed more than one vt subtype in its genome, and among them the most frequent combination was vt(1)/vt(2), but we also observed multiple combinations among vt(2) subtypes. Differences in verotoxicity titers were found among a selection of 54 isolates. Among isolates with a single vt(2) variant, those carrying the vt(2) subtype had high titers under both uninduced and induced conditions. However, the highest increase in cytotoxicity under mitomycin C treatment was detected among the strains carrying vt(2vha) or vt(2hb) variants. Notably, the isolates carrying the vt(1) subtype showed a lesser increase than that of most of the vt(2)-positive VTEC strains. Furthermore, the presence of more than one vt gene variant in the same isolate was not reflected in higher titers, and generally the titers were lower than those for strains with only one gene variant. The main observation was that both basal and induced cytotoxic effects seemed to be associated with the type and number of vt variants more than with the serotype or origin of the isolate.


Assuntos
Doenças dos Bovinos/microbiologia , Infecções por Escherichia coli/veterinária , Variação Genética , Carne/microbiologia , Toxinas Shiga/biossíntese , Toxinas Shiga/genética , Escherichia coli Shiga Toxigênica/isolamento & purificação , Animais , Bovinos , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/biossíntese , Proteínas de Escherichia coli/classificação , Proteínas de Escherichia coli/genética , Expressão Gênica , Genótipo , Fenótipo , Toxinas Shiga/classificação , Escherichia coli Shiga Toxigênica/genética
10.
Foodborne Pathog Dis ; 8(9): 1019-23, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21542769

RESUMO

Verocytotoxigenic Escherichia coli (VTEC) can produce serious human illness linked to the consumption of contaminated food, mainly of bovine origin. There is growing concern about non-O157 VTEC serotypes, which in some countries cause severe infections in a proportion similar to O157:H7 strains. As several epidemiological studies indicated the important role of meat as the major vehicle in the transmission of this pathogen to human consumers, our aim was to investigate the genetic diversity among non-O157:H7 VTEC isolated from raw beef products. We performed a multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA), and to our knowledge, this is the first time that VTEC serotypes O8:H19, O112:H2, O113:NM, O171:NM, ONT:H7, ONT:H19, and ONT:H21 were typed by this method. MLVA typing grouped the total number of strains from this study (51) into 21 distinct genotypes, and 11 of them were unique. Several MLVA profiles were found in different serotypes, O178:H19 being the most variable. The isolates could be principally discriminated by alleles of three of seven loci studied (CVN001, CVN004, and CVN014), and on the other hand, CVN003 rendered null alleles in all the isolates. As some VNTR markers might be serotype specific, it is possible that the implementation of new VNTR loci will increase intraserotype discrimination.


Assuntos
Genótipo , Carne/microbiologia , Tipagem de Sequências Multilocus , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/isolamento & purificação , Adesinas Bacterianas/genética , Alelos , Animais , Argentina , Bovinos , Proteínas de Escherichia coli/genética , Proteínas Hemolisinas/genética , Repetições Minissatélites , Filogenia , Sorotipagem , Toxinas Shiga/genética , Escherichia coli Shiga Toxigênica/classificação , Especificidade da Espécie
11.
Braz J Microbiol ; 42(2): 711-5, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24031684

RESUMO

We investigated the presence of the gene of subtilase cytotoxin (SubAB), described in certain highly virulent verocytotoxigenic E. coli strains, in isolates from Argentina and its relation with other virulence factors. The gene subA was present in eae-negative strains mostly associated with saa, vt2 and ehxA genes.

12.
Int J Med Microbiol ; 300(4): 212-7, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19850517

RESUMO

Although serotype O157:H7 has been implicated in most cases of haemolytic-uraemic syndrome (HUS), there is growing concern about non-O157 serotypes of verocytotoxigenic Escherichia coli (VTEC). Multiple-locus variable-number tandem repeat analysis (MLVA) has been focused on the specific typing of O157:H7 isolates, but recently, a generic MLVA assay for E. coli and Shigella has been developed. We performed a study of the polymorphism in 7 generic VNTR loci both in VTEC O157:H7 and non-O157 isolates from Argentina, in order to asses the ability of the method to type this group of isolates and to get insight into their genetic diversity. Sixty-four isolates from cattle, patients with diarrhoea, and contaminated food belonging to 8 different serotypes were studied. All of them could be typed by this method and revealed 41 different MLVA genotypes. The MLVA dendrogram showed 2 main clusters which corresponded to O157:H7 and non-O157, respectively. Our results confirm the suitability of this MLVA method for analyzing VTEC isolates belonging to several serotypes, both O157:H7 as well as non-O157, highlight the genetic variability of the O157:H7 serotype and the need of additional research in order to find more VNTR loci that could allow a higher discrimination among non-O157 VTEC.


Assuntos
Doenças dos Bovinos/microbiologia , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/veterinária , Microbiologia de Alimentos , Variação Genética , Escherichia coli Shiga Toxigênica/classificação , Escherichia coli Shiga Toxigênica/isolamento & purificação , Animais , Argentina/epidemiologia , Técnicas de Tipagem Bacteriana , Bovinos , Análise por Conglomerados , Impressões Digitais de DNA , DNA Bacteriano/genética , Infecções por Escherichia coli/microbiologia , Genótipo , Humanos , Repetições Minissatélites , Epidemiologia Molecular , Sensibilidade e Especificidade , Sorotipagem , Escherichia coli Shiga Toxigênica/genética
13.
Zoonoses Public Health ; 67(1): 44-53, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31868306

RESUMO

Shiga toxin-producing Escherichia coli (STEC) can cause diarrhoea and severe diseases in humans, such as haemolytic uraemic syndrome. STEC virulence is considered to correlate with the amount of Shiga toxins (Stx) produced, especially Stx2, whose subtype Stx2a is most frequently associated with high virulence. Stx are encoded in prophages, which play an important role in STEC pathogenesis. The aim of this study was to evaluate stx2a expression levels and Stx2a phage production using qPCR and the double-agar-layer method in 29 STEC strains, corresponding to serotypes O26:H11 (6), O91:H21 (1), O145:H- (11) and O157:H7 (11), isolated from cattle and humans. Results were then tested for possible associations with serotype, origin or some genetic features. We observed heterogeneous levels of stx2a expression and Stx2a phage production. However, statistical comparisons identified a higher stx2a expression in response to mitomycin C in strains isolated from cattle than in those from humans. At the same time, compared to stx2a /stx2c strains, stx2a strains showed a higher increase in phage production under induced conditions. Notably, most of the strains studied, regardless of serotype and origin, carried inducible Stx2a phages and evidenced expression of stx2a that increased along with phage production levels under induced conditions.


Assuntos
Bacteriófagos/fisiologia , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Toxina Shiga II/metabolismo , Escherichia coli Shiga Toxigênica/metabolismo , Escherichia coli Shiga Toxigênica/virologia , Alquilantes/farmacologia , Animais , Bovinos , Humanos , Mitomicina/farmacologia , Prófagos , RNA Bacteriano , Toxina Shiga , Toxina Shiga II/química , Toxina Shiga II/genética , Escherichia coli Shiga Toxigênica/efeitos dos fármacos , Escherichia coli Shiga Toxigênica/genética
14.
Braz J Microbiol ; 40(4): 927-32, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24031443

RESUMO

The aim of this work was to adapt described MLVA protocols to the molecular typing and characterization of VTEC O157:H7 isolates from Argentina. Nine VNTR loci were amplified by PCR showing diversity values from 0.49 to 0.73. Nine MLVA profiles were observed and the cluster analysis indicated both unrelated and closely related VTEC O157:H7 strains. In spite of the limited number of isolates studied, the panel of VNTR used made it possible to perform a first approach of the high genetic diversity of native strains of O157:H7 by MLVA.

15.
J Med Microbiol ; 56(Pt 11): 1474-1478, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17965347

RESUMO

Verotoxin-producing Escherichia coli (VTEC) are important pathogens that can cause severe human disease, including haemorrhagic colitis and haemolytic-uraemic syndrome. A new variant of verotoxin, vt2g, has recently been described. It was possible to find this variant for the first time in Argentina among VTEC isolated from cattle. The present study evaluated the identification of this gene with three conventional methods used for subtyping the vt2 gene. The results show that it is possible to screen VTEC strains for the presence of vt2g without the implementation of new protocols.


Assuntos
Técnicas de Tipagem Bacteriana/métodos , Toxina Shiga II/genética , Escherichia coli Shiga Toxigênica/classificação , Escherichia coli Shiga Toxigênica/genética , Animais , Argentina , Infecções por Escherichia coli/microbiologia , Humanos
16.
Res Microbiol ; 157(3): 263-6, 2006 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-16171978

RESUMO

The pathogenesis of verocytotoxigenic Escherichia coli (VTEC) infection in humans is multifactorial, given that verocytotoxins are the principal virulence factor. Most strains causing serious diseases possess the eae gene that encodes the adhesin intimin, but its presence is not essential for virulence as some cases are caused by eae-negative strains. An autoagglutinating adhesin designated Saa was found in some eae-negative strains. This protein varies in size as a consequence of variation in the number of copies of a 37-aa repeat unit in the C-terminal region. Based on these findings, we designed PCR primers to amplify the region coding for these differences to detect saa gene variants present in VTEC strains isolated in Argentina from cattle and meat. The gene saa was detected in 36 (31.6%) eae-negative strains and 5 variants were found. Strains isolated from cattle possessed 4 saa variants, whereas 2 variants were present in isolates from meat. Saa variant 1 predominated (18 strains) and was distributed in strains isolated both from cattle and from meat. Our study revealed the existence of two novel saa variants, termed 4 and 5, which have a higher number of 111-bp repeats than saa genes previously studied.


Assuntos
Adesinas Bacterianas/genética , Bovinos/microbiologia , Proteínas de Escherichia coli/genética , Escherichia coli/genética , Carne/microbiologia , Animais , Escherichia coli/isolamento & purificação , Microbiologia de Alimentos , Variação Genética , Splicing de RNA
17.
J Med Microbiol ; 55(Pt 5): 545-549, 2006 May.
Artigo em Inglês | MEDLINE | ID: mdl-16585641

RESUMO

Most cases of diarrhoea-associated haemolytic uraemic syndrome (HUS) are caused by verocytotoxin-producing Escherichia coli (VTEC). Argentina has the highest worldwide incidence of HUS, but with a lower incidence of VTEC O157 : H7 serotype than non-Latin American countries. A large number of VTEC serotypes have been isolated from cattle and cattle-derived food products in Argentina. The aim of this work was to study intraserotype genetic diversity among these VTEC strains by random amplification of polymorphic DNA (RAPD). Strains were selected that belonged to the same serotype, but had been isolated from different sources (cattle and meat). Intraserotype genetic diversity was detected among strains belonging to O20 : H19, O113 : H21, O117 : H7, O157 : H7, O171 : H2 and O174 : H21, but only one RAPD profile corresponded to strains belonging to O91 : H21, although these isolates were from different sources.


Assuntos
Infecções por Escherichia coli/veterinária , Escherichia coli O157/classificação , Escherichia coli/classificação , Polimorfismo Genético , Toxinas Shiga/biossíntese , Animais , Antígenos de Bactérias/análise , Argentina , Bovinos , Doenças dos Bovinos/microbiologia , Impressões Digitais de DNA , DNA Bacteriano/análise , DNA Bacteriano/genética , Escherichia coli/isolamento & purificação , Escherichia coli/patogenicidade , Escherichia coli/fisiologia , Infecções por Escherichia coli/microbiologia , Escherichia coli O157/isolamento & purificação , Escherichia coli O157/patogenicidade , Escherichia coli O157/fisiologia , Variação Genética , Carne/microbiologia , Antígenos O/análise , Técnica de Amplificação ao Acaso de DNA Polimórfico , Sorotipagem
18.
Front Microbiol ; 7: 992, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27446032

RESUMO

Induction and propagation of bacteriophages along the food production chain can represent a significant risk when bacteriophages carry genes for potent toxins. The aim of this study was to evaluate the effect of different compounds used in the food industry on the growth of Shiga toxin-producing Escherichia coli (STEC) and the production of stx-phage particles and Shiga toxin. We tested the in vitro effect of lactic acid, acetic acid, citric acid, disodium phosphate, and sodium citrate on STEC growth. A bacteriostatic effect was observed in most of treated cultures. The exceptions were those treated with sodium citrate and disodium phosphate in which similar growth curves to the untreated control were observed, but with reduced OD600 values. Evaluation of phage production by plaque-based assays showed that cultures treated with sodium citrate and disodium phosphate released phages in similar o lower levels than untreated cultures. However, semi-quantification of Stx revealed higher levels of extracellular Stx in STEC cultures treated with 2.5% sodium citrate than in untreated cultures. Our results reinforce the importance to evaluate if additives and other treatments used to decrease bacterial contamination in food induce stx-phage and Stx production.

19.
Artigo em Inglês | MEDLINE | ID: mdl-26539413

RESUMO

The Shiga-toxin producing Escherichia coli (STEC) may cause serious illness in human. Here we analyze O26:H11 strains known to be among the most reported STEC strains causing human infections. Genetic characterization of strains isolated from animal, food, and clinical specimens in Argentina showed that most carried either stx 1a or stx 2a subtypes. Interestingly, stx 2a-positive O26:H11 rarely isolated from cattle in other countries showed to be an important proportion of O26:H11 strains circulating in cattle and food in our region. Seventeen percent of the isolates harbored more than one gene associated with antimicrobial resistance. In addition to stx, all strains contained the virulence genes eae-ß, tir, efa, iha, espB, cif, espA, espF, espJ, nleA, nleB, nleC, and iss; and all except one contained ehxA, espP, and cba genes. On the other hand, toxB and espI genes were exclusively observed in stx 2-positive isolates, whereas katP was only found in stx 1a-positive isolates. Our results show that O26:H11 STEC strains circulating in Argentina, including those isolated from humans, cattle, and meat products, present a high pathogenic potential, and evidence that cattle can be a reservoir of O26:H11 strains harboring stx 2a.


Assuntos
Infecções por Escherichia coli/microbiologia , Infecções por Escherichia coli/veterinária , Variação Genética , Genótipo , Carne Vermelha/microbiologia , Sorogrupo , Escherichia coli Shiga Toxigênica/classificação , Animais , Argentina , Bovinos , Farmacorresistência Bacteriana , Genes Bacterianos , Humanos , Toxina Shiga I/genética , Toxina Shiga II/genética , Escherichia coli Shiga Toxigênica/genética , Escherichia coli Shiga Toxigênica/isolamento & purificação , Fatores de Virulência/genética
20.
BMC Microbiol ; 2: 3, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-11869455

RESUMO

BACKGROUND: Horses infected with Leptospira present several clinical disorders, one of them being recurrent uveitis. A common endpoint of equine recurrent uveitis is blindness. Serovar pomona has often been incriminated, although others have also been reported. An antigenic relationship between this bacterium and equine cornea has been described in previous studies. A leptospiral DNA fragment that encodes cross-reacting epitopes was previously cloned and expressed in Escherichia coli. RESULTS: A region of that DNA fragment was subcloned and sequenced. Samples of leptospiral DNA from several sources were analysed by PCR with two primer pairs designed to amplify that region. Reference strains from serovars canicola, icterohaemorrhagiae, pomona, pyrogenes, wolffi, bataviae, sentot, hebdomadis and hardjo rendered products of the expected sizes with both pairs of primers. The specific DNA region was also amplified from isolates from Argentina belonging to serogroups Canicola and Pomona. Both L. biflexa serovar patoc and L. borgpetersenii serovar tarassovi rendered a negative result. CONCLUSIONS: The DNA sequence related to the antigen mimicry with equine cornea was not exclusively found in serovar pomona as it was also detected in several strains of Leptospira belonging to different serovars. The results obtained with L. biflexa serovar patoc strain Patoc I and L. borgpetersenii serovar tarassovi strain Perepelicin suggest that this sequence is not present in these strains, which belong to different genomospecies than those which gave positive results. This is an interesting finding since L. biflexa comprises nonpathogenic strains and serovar tarassovi has not been associated clinically with equine uveitis.


Assuntos
Antígenos de Bactérias/genética , Córnea/imunologia , Córnea/microbiologia , DNA Bacteriano/genética , Leptospira interrogans serovar pomona/genética , Leptospira/genética , Animais , Doenças da Córnea/imunologia , Doenças da Córnea/microbiologia , Doenças da Córnea/veterinária , Doenças dos Cavalos/genética , Doenças dos Cavalos/imunologia , Cavalos , Leptospirose/genética , Leptospirose/imunologia , Leptospirose/veterinária
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