Genotypic diversity of Salmonella ser. Abortusequi isolates from Argentina.

BACKGROUND: Salmonella enterica subsp. enterica serovar Abortusequi (S. Abortusequi) is a serotype restricted to equines, which produces abortion outbreaks. Nowadays the disease is being reported in different countries including Argentina thus generating an important impact in the equine industry. Molecular characterization of the 95 kb virulence plasmid and the spvC gene of S. Abortusequi demonstrated their importance in the pathogenicity of the serotype. In the last decades, high clonality of S. Abortusequi was identified in Japan, Mongolia and Croatia. OBJECTIVES: The aim of this work was to characterize S. Abortusequi isolates obtained in Argentina between 2011 and 2016 by virulence-gene profiling and pulsed-field gel electrophoresis. STUDY DESIGN: Case report. METHODS: S. Abortusequi isolates were studied by virulence-gene profiling and pulsed-field gel electrophoresis. RESULTS: Four virulence profiles and nine pulsed-field gel electrophoresis pulsotypes were identified among the 27 isolates included in the study. Different strains were found in the same outbreak and/or farm suggesting the presence of different sources of infection or mutation of isolates. MAIN LIMITATIONS: The number of related and nonrelated strains. More isolates may be necessary for a more intensive study. CONCLUSIONS: Most strains presented the same virulence profile, being positive for all the studied genes except gipA and sopE1, which are involved in intestinal virulence. Only few isolates showed different results in the same outbreak or farm. Unlike other studies, our results demonstrate a considerable diversity of S. Abortusequi pulsed-field gel electrophoresis pulsotypes, which suggests that different sources of infection may be involved within the same outbreak.

Prevalence, associated risk factors, and antimicrobial resistance profiles of non-typhoidal Salmonella in large scale swine production in Córdoba, Argentina.

Non-typhoidal Salmonella is considered a major public health concern. The growing relevance of pigs as reservoir of Salmonella spp. has prompted several countries to set up surveillance and control programs to fight Salmonella infection in swine and reduce public health risk. In the last decade, pork production in Córdoba increased significantly to become one of the most important pig production provinces in Argentina. The aim of this study was to estimate Salmonella spp. prevalence and associated risk factors in large scale-farms in this province. Mesenteric lymph nodes (MLN) of 580 pigs from 20 finishing large-scale farms were collected between 2014 and 2015 to estimate Salmonella infection. A prevalence of 41.5% (95%CI: 37.6-45.6%) was observed. Two major risk factors were significantly associated with Salmonella infection, both related to the pre-slaughter period (distance from the farm to the slaughterhouse and lairage time), highlighting the need to pay special attention to pre-slaughter practices in the province. Shortening transport times and complying with national regulations for lairage time at slaughter may help to reduce the prevalence of infection. Sixteen different serovars were identified, being S. Anatum and S. Typhimurium the most prevalent ones. Moreover, two isolate of the monophasic variant of Salmonella Typhimurium (I 4,5,12:i:-) resistant to enrofloxacin and which also displayed multidrug resistance was isolated for first time from pigs in Córdoba. The moderate to high levels of antimicrobial resistance detected for antibiotics commonly used in the pig sector suggested the need for implementing a plan to limit their use in the province.

[Serovars of Salmonella enterica subspecies enterica and its antimicrobial resistance in slaughterhouse pigs]. / Serovariedades de Salmonella enterica subespecie enterica en porcinos de faena y su resistencia a los antimicrobianos.

A study was carried out in order to determine the prevalence of Salmonella and its serovars among porcine slaughterhouses, to evaluate the antimicrobial resistance profiles and to know the presence of class 1 integrons as possible reservoir of resistance. From a total of 386 samples from four porcine slaughterhouses of Buenos Aires and Santa Fe Provinces (Argentina), 93 (24.1%) Salmonella enterica subspecies enterica strains were identified, 52 (55.9%) from cecal contents and 41 (44.1%) from ileocecal lymph nodes. Thirteen serovars of S. enterica were found, the most prevalent were: S. Schwarzengrund, S. Heidelberg, S. subspecie I 6,8:e,h:-, S. Derby and S. Bredeney. Fifteen antimicrobials by the agar dilution method were tested: amikacin, gentamicin, ciprofloxacin, cephalotin, cefotaxime, enrofloxacin, fosfomycin, polimixin-B, tetracycline, chloramphenicol, streptomycin, trimethoprim-sulfamethoxazole, ampicillin, nitrofurantoin, and nalidixic acid. According to the CIM determination, 73% Salmonella enterica subspecies enterica strains were sensible to all the antimicrobials tested. Antimicrobial resistance was observed to tetracycline in 24 (25.8%) of 93 strains, to chloramphenicol in 22 (23.7%), to streptomycin in 22 (23.7%), to trimethoprim-sulfamethoxazole in 20 (21.5%), to ampicillin in 18 (19.4%), to nitrofurantoin in 3 (3.2%) and to nalidixic acid in 3 (3.2%). Some isolates of S. Typhimurium, S. Heidelberg, S. Derby, S. Orion showed multidrug resistance and carried the class 1 integrase gene. The highest percentage of resistance corresponded to the antimicrobials currently used in veterinary and porcine farms.

[Characterization of Vibrio cholerae non-O1 and non-O139 isolates associated with diarrhea]. / Caracterización de aislamientos de Vibrio cholerae no-O1, no-O139 asociados a cuadros de diarrea.

Vibrio cholerae, etiologic agent of cholera, is transmitted to humans by ingestion of contaminated food or water. Even though serogroups O1 and O139 are the ones usually associated to epidemic cholera, isolates from other serogroups also cause gastroenteritis and extraintestinal infections. During the period 2003-2005, presence of V. cholerae in stools was investigated in children with diarrhea that seaked assistance at the Niño Jesús Hospital in Tucumán. Thirty four isolates of V. cholerae non-O1, non-O139 were recovered. We characterized the isolates studying its virulence factors by PCR, antimicrobial susceptibility patterns and genetic diversity by pulsed-field gel electrophoresis. Eight virulence patterns were obtained although no isolate was positive for the cholera toxin or the thermostable toxin. Four isolates were positive for the type three secretion system. The 17.6% of the isolates were resistant or intermediate to ampicillin and 5.9% were resistant to trimethoprim-sulfamethoxazole. By Sfil-PFGE, all isolates were genetically very diverse, as 27 different patterns were identified in 29 typeable isolates by pulsed-field gel electrophoresis. Although it has a low incidence, V. cholerae continues to be a causative agent of diarrhea in children, who are affected by a variety of circulating strains of V. cholerae non-O1, non-O139.

Prevalence, antimicrobial resistance profile and comparison of selective plating media for the isolation of Salmonella in backyard chickens from Entre Rios, Argentina.

This study was conducted to estimate the apparent prevalence of Salmonella spp. in birds kept under backyard system in Entre Ríos, Argentina, and determine the performance of two selective plating media used for Salmonella isolation, and the antimicrobial resistance of the isolated. Also, the association of farms characteristics with Salmonella presence was evaluated. A total of 657 backyard chickens and 15 gooses were sampled one time by cloacal swab, belonging to 51 and one family farms, respectively, and four counties in Entre Rios state from April 2014 to May 2015. Only four samples from backyard chickens belonged to three family farms from Uruguay County were positive to Salmonella spp., so the apparent prevalence was 0.6% for this kind of chicken. Four serovars were isolated (Salmonella ser. Lille, S. ser. Newport, S. ser. Enteritidis and S. ser. Rissen), which were susceptible to all antibiotics tested with the exception of erythromycin. For Hektoen enteric agar and brilliant green agar, relative specificity and positive predictive value were 1, and the relative sensitivity and negative predictive value did not show any difference between them. The agreement was very good between these two plating media. None of the variables studied could be selected to calculate the risk factors associated with Salmonella isolation because p > .15. Although the prevalence of Salmonella spp. is low in backyard birds in Entre Rios, the presence of S. ser. Enteritidis should not be discounted, because it is found in the county that concentrates a large population of intensive poultry production in the state.

Prevalence, antimicrobial resistance profile and comparison of selective plating media for the isolation of Salmonella spp. in free-ranging waterfowl from Entre Rios, Argentina.

The present study was conducted to estimate the apparent prevalence of Salmonella spp. in free-ranging waterfowl that inhabitant Entre Ríos, Argentina, determine the antimicrobial resistance of the isolated, and compare the performance of two selective plating media used for Salmonella isolation. Five hundred ninety nine free-living waterfowl were sampled one time by cloacal swab from April 2014 to July 2016. Only 6 samples from waterfowl belonged to all counties sampled were positive to Salmonella spp., so the apparent prevalence was 1%. Four serovars were isolated (Salmonella ser. Typhimurium, S. ser. Schwarzengrund, S. enterica subsp. I [4,12: i: -], S. enterica subsp. IIIb [60: r: e, n, x, z15]), which were susceptible to 15 antibiotics tested and resistant to erythromycin. Furthermore, some strains showed an intermediate resistant to neomycin, ciprofloxacin and/or streptomycin. The multiple antibiotic resistances index was 0.05. For Hektoen enteric agar and Salmonella Shigella agar, the relative accuracy, sensitivity, specificity, positive predictive value, and negative predictive value did not show any difference between them. The agreement was good between these two plating-media and the difference between these plating-media was not statistically significant. The low prevalence of Salmonella spp. in waterfowl in Entre Rios should not be discounted, since Salmonella ser. Typhimurium was the most prevalent serovar and some free-ranging waterfowl species studied can migrate from/to different countries, increasing the possibility to cross-contaminated Salmonella to resident or other migrant birds.

Salmonella enteritidis in Argentina.

A significant increase in the number of isolations of Salmonella enteritidis has been observed in Argentina since 1986. Outbreaks of foodborne diseases in humans were associated with the consumption of raw or undercooked hens' eggs. Between 1986 and the first 6 months of 1993 there were 150 outbreaks reported, affecting more than 6000 persons. A total of 71.3% of these outbreaks were confirmed by stool cultures, and 47.3% by bacteriological study of the food implicated in the outbreak. A permanent surveillance of salmonellosis is imperative, taking into account the persistence of Salmonella enteritidis isolations in sporadic cases and in new outbreaks.

[Salmonella taxonomy]. / Taxonomía de Salmonella.

Throughout the years, Salmonella nomenclature has suffered continual revisions, due to the confusion created by the different criteria adopted by the several groups of researchers. At the present time, it is recognized that the genus Salmonella is a single species, composed by seven taxa, with the level of subspecies (subsp.), which can be divided into serovars, described in the Kauffmann-White scheme. The name of four the species type Salmonella is Salmonella enteral sp. nov. nom. rev. The serovar of the taxon I is designated, for instance, Salmonella subsp. I ser. Typhimurium. For the other taxa, less frequent in human or animal pathology, the name of the subsp., followed by the antigenic formula (e.g. Salmonella subsp. IV 50: b-) is used. This criterion has been validated by the International Committee of Systematic Bacteriology and the names of the serovars are included in the Approved Lists of Bacterial Names.

[Significance of Salmonella enteritidis in outbreaks of diseases transmitted by foods in Argentina, 1986-1988]. / Importancia de la Salmonella enteritidis en brotes de enfermedades transmitidas por alimentos en Argentina, años 1986-1988.

This paper reports on the outbreaks of food-borne-diseases due to Salmonella Enteritidis which occurred in Argentina between 1986 and 1988. In 39 registered episodes 210 strains were isolated from human feces (28 outbreaks) and 59 from food (23 outbreaks). More than 2,500 people in different provinces were affected, the chief characteristics of the clinical picture being the gravity of the symptoms (high temperature, vomiting, diarrhea and severe dehydration). The main source of infection was related to raw eggs, eaten in the form of home-made mayonnaise. It is considered necessary to carry out an effective control of poultry products, as well as a permanent surveillance of salmonellosis.

[New worldwide Salmonella serovar isolated in a case of diarrhea]. / Nueva serovariedad mundial de Salmonella aislada de un caso de diarrea.

The isolation of a new serovar of Salmonella from fecal material belonging to a child with acute diarrhea in the ville of Orán, province of Salta, is reported. Because of its biochemical characteristics it was classified within the sub-species IV, taxon 5, according to the present nomenclature for this genus, being its antigenic structure 50:b:-(S IV 50:b:-).

[Salmonella Freetown: 1st isolation in Argentina]. / Salmonella Freetown: primer aislamiento en Argentina.

In this paper we report the first case of Salmonella Freetown in Argentina. It was isolated from a stool sample of a child of 1 month and 7 days, assisted as outpatient in the Hospital de Niños Dr. Ricardo Gutiérrez of the city of Santa Fe. On the basis of the biochemical characteristics and antigenic formulae, this new serovar belongs to the species Salmonella enterica subspecies enterica.

[Presentation of salmonellosis in the Tandil district, Argentina]. / Presentación de salmonelosis en el partido de Tandil, Argentina.

From January 1990 to July 1992 a prospective study on the salmonellosis form of presentation, reservoirs and transmission in Tandil was carried out. Forty strains of Salmonella enterica were isolated with the following distribution: 28 humans (17 children and 11 adults), 6 in foods (1 in raw milk, 3 in well water, 1 in home made mayonnaise and 1 in chicken salad) and 6 in animals (1 in cow, 2 in chicken and 2 in calves). Salmonella Enteritidis was the most frequent isolate. Disease was evident only in a few susceptible hosts and the epidemiological chain could not be determined in all the cases.

[Diagnosis of entero-invasive Escherichia coli associated with diarrhea]. / Diagnóstico de Escherichia coli enteroinvasiva asociada a diarrea.

Sixteen Escherichia coli strains isolated from diarrhea patients, characterized as enteroinvasive (EIEC) by the keratoconjunctivitis test (Sereny test), and 15 non-EIEC strains, were studied. The aim of this study was to establish a possible correlation between the Sereny test and several other tests as enzyme-linked immunosorbent assay (ELISA) and biochemical markers, which are more easily accessible to general practice laboratories. Strains were assayed for the virulence marker antigen (the outer membrane proteins) by direct ELISA, biochemical tests, antimicrobial susceptibility profile and serotyping. Mean optical density (OD) values in the ELISA were 2.018 +/- 0.336 for EIEC strains, and 0.569 +/- 0.283 for non-EIEC strains. Difference between the OD values of the two groups was found to be significant at p < 0.01 by the one-tailed Student's test. One (6.2%) of the 16 Sereny test-positive strains was negative by ELISA. Considered as a group, the EIEC strains are rather heterogeneous in their biochemical characteristics. Lysine decarboxylase test appeared as the most relevant assay, since all EIEC strains were negative for this enzyme, whereas 66.7% of non-EIEC strains were positive. Other helpful tests performed for strain characterization were: gas production from glucose and from glycerol, sucrose and salicin fermentation, and esculin hydrolysis (p < 0.01). However, strains behaviour was variable with these tests. Differences between both groups of strains with regard to mucate utilization and dulcitol fermentation was significative only to a 5% level. Antibiotic sensitivity patterns showed differences between EIEC and non-EIEC strains: 37.5% of the former vs 80% of the latter, were resistant to at least four of the antibiotics tested.(ABSTRACT TRUNCATED AT 250 WORDS)

[Bacteria of the genus Yersinia in chickens for human consumption and in balanced bird food]. / Investigación de bacterias del género Yersinia en pollos destinados al consumo y en alimento balanceado para aves.

Yersinia was investigated in 50 skin samples of chicken carcasses from retail shops and 65 samples of balanced food for domestic fowl. Enrichments were performed in saline phosphate buffer 0.067 M, pH 7.6 and post-enriched in 0.5% KOH. Subcultures were performed in Salmonella-Shigella agar and MacConkey agar. Isolates were identified through biochemical, serological and lysotyping methods. The following biovar (B), serovar (O) and phagovar (Lis) were isolated from chickens: Y. enterocolitica (five strains) B:1:O:6,47;Lis Xz; B:1;O:6:Lis Xz; B:1:O:5,Lis Xz; Y.intermedia (two strains) B:1;O:52;Lis Xz; B:1;O:52,53,54;Lis Xz (NRA, nitrate reductase type A); Y. frederiksenii (two strains) O:10,K1,25,35,38,46:Lis Xz; (citrate): O:10,K1,25,35,38,46:Lis Xz (ONPG-: citrate +); Y. kristensenii (one strain) does not agglutinate; Lis Xo. Yersinia were not isolated from balanced food for domestic fowl. Virulence tests (calcium dependency and autoagglutination at 37 degrees C) were negative in all instances. It is concluded from this study that Yersinia isolated from chickens are without pathogenic importance.

[Evaluation of the hygienico-sanitary quality of fresh noodles]. / Determinación de la calidad higiénico-sanitaria de fideos frescos.

Total mesophyllic aerobes (MT), total coliforms (CT), fecal coliforms (CF), Escherichia coli (EC), molds and yeasts (HyL) and Salmonella were studied in 50 samples of fresh noodles (32 to 35% water) prepared with dried or with liquid egg. Values obtained were: (in parenthesis number of positive samples) MT, 10(4) to 10(6) CFU/g (48%). HyL, 10(2) to 10(4) CFU/g (76%). CT, 4 to 100/g (32%) and 460/g (2%). CF, 3 to 10/g (14%) and 21/g (6%). For EC only two samples were positive with 4 and 9/g respectively. The same serovar of Salmonella (S. oranienburg) was detected in 88% of the samples.

[Comparative study of 4 methods for isolating Salmonella from surface waters]. / Estudio comparativo de cuatro métodos de aislamiento de salmonelas de aguas superficiales.

The study presented here is the first stage of a project designed to determine the presence of Salmonella serotypes in Lujan river waters, which flow beside the urban area of the homonymous city, in the province of Buenos Aires. It consisted in a comparative study of four methods for Salmonellae detection in 200 samples: Tetrathionate-brilliant green; mannitol-selenite; Rappaport 25 and modified Rappaport-Vassiliadis broth, each of them with and without pre-enrichment in buffered peptone water. The submerged gauze technique was applied to the sampling in three different spots of the river: at the town center, two km water above, and two down-stream from the city. Best results were obtained when modified Rappaport-Vassiliadis enrichment broth and brilliant green agar with 0.25% of sodium deoxycholate were used, after pre-enrichment of the samples in buffered peptone water. Salmonella were isolated from 46% of the samples studied, and 16 serotypes were identified: S. Typhimurium, S. Enteritidis, S. Infantis, S. Mbandaka, S. Israel and S. Subspecies IV 18 z36: z38:-, among them.

[Agglutination of hen egg-yolk immunoglobulins (IgY) against Salmonella enterica, serovar enteritidis]. / Aglutinación de inmunoglobulinas de yema de huevo de gallina (IgY) contra Salmonella enterica serovariedad enteritidis.

Two groups of 6 laying hens were used to produce IgY. In the vaccinated group (V), hens were injected by intramuscular route with two doses of a Salmonella enterica serovar Enteritidis bacterin at 20-day interval. In the control group (T) hens remained unvaccinated. Four IgY extractions were performed on the egg production of both groups. The first two extractions were carried out using the yolks obtained from the eggs produced during the 4th and 5th post-vaccination week (extracts 1V and 1T) and the other two using the ones from the 6th, 7th and 8th week (2V and 2T). Starting from the extracts 1V and 1T other products were obtained by freezing-thawing (1V-A and 1T-A) and simple (1V-B and 1T-B) or double (1V-C and 1T-C) flow capillary dialysis concentration. All these products were compared using an ELISA test specific for the detection of chicken antibodies against flagellar antigens of S. Enteritidis. In this test, V extracts were positive whereas T extracts were negative. The extract 1V was more positive than the extract 2V. The extract 1V-C was the most positive and was therefore selected to be used as an antiserum in the agglutination tests. This extract contained 1.9 g/dl of total proteins, 0.028 g/dl of triglycerides and 0.012 g/dl of cholesterol and showed an electrophoretic pattern characteristic of IgY. The 1T-C extract was used as a negative control in the agglutination tests. Slide somatic and tube flagellar agglutination tests were simultaneously carried out using both IgY extracts and a standard rabbit anti-Salmonella (IgG) sera. Overall 367 strains from the Enterobacteriaceae family were tested together with two other strains belonging to the Vibrionaceae family. The 1V-C extract specifically agglutinated S. Enteritidis strains in the same way as the rabbit sera. This extract also agglutinated other Salmonella strains antigenically related to S. Enteritidis. Salmonella which did not share somatic or flagellar antigens with S. Enteritidis, other different species of the Enterobacteriaceae family and the two strains of the Vibrionaceae family were all negative. None of the strains tested was agglutinated by the 1T-C extract. This paper show that it is possible to use specific IgY to identify S. enterica serovars. The more extended use of IgY for diagnostic purposes may be a convenient way to complement the current use of mammal polyclonal antibodies.

[The first isolations of Salmonella Zaiman in humans]. / Primeros aislamientos de Salmonella Zaiman en humanos.

This paper describes the first three Salmonella Zaiman cases in children of more than one year old with acute infectious diarrhoea of less than seven days evolution, in the Pediatric Department of R. Madariaga Hospital in Posadas, Misiones. This sero-variety was isolated by hemoculture in an 11 year old girl with urinary infection and sepsis. This Salmonella is a new sero-variety isolated from Zaiman river which flows through suburbs of Posadas.

[Cases of gastroenteritis associated to Vibrio cholerae no 01 in Oran, Salta]. / Casos de gastroenteritis asociados a Vibrio cholerae no O1 en Orán, Salta.

Forty-one sporadic cases of non-O group 1 Vibrio cholerae gastroenteritis were detected in Orán, Salta, between February 1992 and February 1995. The frequency of isolation was 0.9% of the diarrhea cases. Out of 41 patients, 21 (51.2%) were older than 15 years and 25 (60.9%) were male. All the patients had diarrhea, 24 (58.5%) had watery stools and 6 (14.6%) cholera-like diarrhea; 10 (24.4%) presented vomiting and 12 (29%) mild dehydration. Six malnourished children who suffered from diarrhea with moderate dehydration for more than a week, were hospitalized. V. cholerae non O1 and Shigella flexneri were isolated from one patient, during the first outbreak and V. cholerae non O1 and Salmonella IV 50:b:- were recovered simultaneously from another patient during the fourth outbreak. A 72 year old woman died during the second cholera outbreak. The symptoms were: watery diarrhea, vomiting, fever and mild dehydration. A strain of V. cholerae O5, that did not produce cholera toxin, heat-stable enterotoxin, Kanagawa-like hemolysin or verocitotoxin was detected. It was positive for El Tor hemolysin and D-mannose and L-fucose resistant cells-associated hemagglutinins. Among the 41 isolates studied, all were oxidase and indole positive, fermented glucose, saccharose and mannitol. They were all motile, produced lysine and ornithine decarboxylases but not arginine dihydrolase or hydrogen sulfide. They were sensitive to O129 vibriostatic compound. None of them belonged to O1 or O139 serogroup and they did not produce cholera troxin. Among the V. cholerae non O1 strains isolated, 9.5% were resistant to ampicillin and 4.9% to trimethoprim-sulfamethoxazole. Active surveillance had shown that V. cholerae non-O1 is not an important agent of diarrhea in Orán, Salta.

Environment and virulence factors of Vibrio cholerae strains isolated in Argentina.

AIMS: To determine the presence of Vibrio cholerae in different areas of Argentina in three sample types, to determine the composition of planktonic communities in areas at which this pathogen was detected and to characterize the virulence properties and antimicrobial resistance of the recovered environmental isolates. METHODS AND RESULTS: Water and plankton samples were collected in marine, brackish and freshwater environments. Vibrio cholerae non-O1, non-O139 was isolated in 36.1% of the samples analysed. The micro-organism was detected in freshwater but not in marine or brackish samples. No relationship was found between isolation of V. cholerae and presence of any species of plankton. All the isolates presented very similar virulence profiles by PCR, lacking ctxA and tcpA El Tor and containing hlyA (98.7%), rtxA (99.0%), toxR (98.7%) and stn-sto (1.9%). Resistance to ampicillin was found in both Tucumán (21%) and Buenos Aires isolates (45%). CONCLUSIONS: We identified two geographic areas in Argentina where V. cholerae was present: freshwaters of the rivers from Tucumán and the Río de la Plata. SIGNIFICANCE AND IMPACT OF THE STUDY: The identification of V. cholerae strains in the environment, carrying both virulence factors and resistance to antimicrobial agents, highlight the need for a continuous and active surveillance of this pathogen.