Abstract Diarrheagenic Escherichia coli comprises a heterogeneous group of pathotypes or pathogenic variants that share phenotypic characteristics with marked differences in virulence genes, colonization sites, pathogenesis, clinical presentation, and epidemiology of infection. The most studied pathotypes are Shiga toxin-producing E.coli (STEC), enterotoxigenic E.coli (ETEC), enteropathogenic E.coli (EPEC), enteroaggregative E.coli (EAEC), and enteroinvasive E.coli (EIEC). The objective of the study was to characterize the isolates of diarrheagenic E.coli from an outpatient pediatric population with diarrhea attended in two public hospitals from Buenos Aires, Argentina. Diarrheagenic E.coli pathotypes were investigated by amplifying characteristic virulence gene fragments: intimin (eae), heat-labile toxin (lt), heat-stable toxins (stp, sth), invasion plasmid antigen H (ipaH), transcriptional activator R (aggR) and Shiga toxins (stx1, stx2). Molecular subtyping of isolates was performed using PFGE (XbaI). Diarrheagenic E.coli was detected in 14% (84/601) of cases. The EAEC pathotype was prevalent, while ETEC, STEC, EPEC and EIEC were found in a lower proportion. EAEC isolates exhibited a high degree of genetic diversity. All pathotypes were found in children under 5years of age, while only EAEC, EIEC and ETEC were detected in the older population. Future studies that include the characterization of isolates from a greater number of genes and populations from other geographical areas will be necessary to determine the relevance of diarrheagenic E.coli in Argentina.

Resumen Escherichia coli diarreogénica abarca un grupo heterogéneo de patotipos o variantes patogénicas que comparten características fenotípicas con marcadas diferencias en genes de virulencia, sitios de colonización, patogenia, presentación clínica y epidemiología de la infección. Los patotipos más estudiados son E.coli productora de toxina Shiga (STEC), E.coli enterotoxigénica (ETEC), E.coli enteropatogénica (EPEC), E.coli enteroagregativa (EAEC) y E.coli enteroinvasiva (EIEC). El objetivo del estudio fue caracterizar los aislamientos de E.coli diarreogénica provenientes de población pediátrica ambulatoria con diarrea, atendida en dos hospitales públicos de Buenos Aires, Argentina. Los patotipos de E.coli diarreogénica se investigaron mediante la amplificación de fragmentos de genes de virulencia característicos: intimina (eae), toxina termolábil (lt), toxinas termoestables (stp, sth), antígeno plasmídico de invasiónH (ipaH), activador transcripcional R (aggR) y toxinas Shiga (stx1, stx2). La subtipificación molecular de aislamientos se realizó mediante PFGE (XbaI). E.coli diarreogénica fue detectada en el 14% (84/601) de los casos. El patotipo EAEC fue prevalente, mientras que ETEC, STEC, EPEC y EIEC fueron hallados en menor proporción. Los aislamientos de EAEC presentaron un alto grado de diversidad genética. Todos los patotipos fueron hallados en niños menores de 5años, mientras que solamente EAEC, EIEC y ETEC fueron detectados en población de mayor edad. Futuros estudios que incluyan la caracterización de aislamientos a partir de un mayor número de genes y población de otras áreas geográficas serán necesarios para determinar la relevancia de E.coli diarreogénica en Argentina.

Resumen Las infecciones del torrente sanguíneo asociadas a los cuidados de la salud constituyen una de las principales causas de morbilidad y mortalidad. La infección relacionada con catéteres vasculares es su fuente principal. Las bacterias Gram positivas, especialmente Staphylococcus spp., constituyen uno de los agentes etiológicos más frecuentes. Objetivo: evaluar la actividad inhibitoria del AP7121 sobre la adherencia de Staphylococcus aureus en catéteres vasculares. Se utilizó la cepa productora de biofilm S. aureus ATCC 35556 (SA). Se estimó CIMAP7121 para SA, se inocularon segmentos de 20 mm de catéter vascular (n = 3) con 104 UFCmL-1 de SA. Se probaron tres esquemas diferentes (A: simultáneo, B: anterior y C: después del desafío bacteriano) utilizando 1 x CIMAP7121. Se incluyeron grupos de control en cada esquema. La CIMAP7121 fue 0,48 mg/L. Con los esquemas A y B se logró una reducción de 2 logaritmos que representa una disminución del 99 % de células viables. El tratamiento posterior a la exposición con AP7121 (esquema C) produjo una reducción de 1 logaritmo que representa una disminución del 90 % de células viables. Estos resultados sugieren una rápida actividad antimicrobiana de AP7121 que podría ser beneficiosa para reducir la adherencia bacteriana en catéteres vasculares.

Abstract Healthcare-associated bloodstream infections are the leading cause of morbidity and mortality in hospitalized patients. Vascular catheter-related infection is its main source. Gram-positive bacteria, mainly Staphylococcus spp., are the most prevalent etiological agents. Our aim was to assess the inhibitory activity of the AP7121 on the Staphylococcus aureus adherence in vascular catheters. The biofilm-producer strain S. aureus ATCC 35556 (SA) was used. MIC AP7121 for SA was performed using 20 mm segments of the vascular catheter (n = 3) were inoculated with 104 UFC∙mL-1 of SA. Three different treatment schemes (A: simultaneous, B: previous, and C: following bacterial challenge) using 1 x MIC AP7121 were tested. Control groups were included in each scheme. The MICAP7121 was 0.48 mg/L. A reduction of 2log10 representing a decrease of 99 % of viable SA cells was achieved with schemes A and B. The post-challenge treatment with AP7121 (scheme C) produced a reduction of 1log10 representing a 90 % decrease of viable SA cells. The results observed in this work suggest an AP7121 fast-antimicrobial activity that could be beneficial to reduce bacterial adherence on medical devices such as vascular catheters.

Resumen Escherichia coli diarreogénica comprende un grupo heterogéneo de cepas que presentan diversos factores de virulencia y causan diferentes síndromes diarreicos. Los patotipos más estudiados son Escherichia coli enteropatogénica (EPEC), Escherichia coli enterotoxigé-nica (ETEC), Escherichia coli enteroagregativa (EAEC), Escherichia coli enteroinvasiva (EIEC) y Escherichia coli productora de toxina Shiga (STEC). El objetivo de este estudio fue estimar la frecuencia de infección de los diversos patotipos de E. coli diarreogénica en una población pediátrica ambulatoria con diarrea, atendida en el Hospital Sor María Ludovica de La Plata, Argentina, durante el período mayo-octubre de 2017. Los patotipos fueron detectados mediante la amplificación molecular de ocho genes de virulencia característicos. Se estudiaron las heces de 211 ninos (76% menores de 5 años). Se detectó infección con E. coli diarreogénica en el 12,3% (n = 26/211) de los niños con diarrea. Los patotipos identificados fueron EAEC, ETEC (todos lt positivos), EPEC y STEC (stx2 y eae positivos). El patotipo EAEC fue prevalente en todos los grupos etarios, mientras que los patotipos ETEC, EPEC y STEC solamente se observaron en niñnos menores de 5 anños. Este estudio constituye el primer reporte de detección por técnicas de amplificación molecular de Escherichia coli diarreogénica en una población pediátrica ambulatoria con diarrea, de la zona de La Plata. Se necesitan estudios más amplios que incluyan la caracterización de los aislamientos abarcando un mayor número de genes, controles asintomáticos, distintas épocas del ano y población de diversas áreas geográficas para esclarecer la relevancia de la infección por E. coli diarreogénica en niños de Argentina.

Abstract Diarrheagenic Escherichia coli is a heterogeneous group of strains that presents various virulence factors and causes different diarrheal syndromes. The most studied pat-hotypes are enteropathogenic Escherichia coli (EPEC), enterotoxigenic Escherichia coli (ETEC), enteroaggregative Escherichia coli (EAEC), enteroinvasive Escherichia coli (EIEC) and Shiga toxin-producing Escherichia coli (STEC). The objective was to estimate the frequency of infec-tion of diarrheagenic E. coli pathotypes in children with diarrhea, attended at the Sor María Ludovica Hospital in La Plata, Argentina, during the period May-October 2017. E. coli pathotypes were detected by molecular amplification of eight characteristic virulence genes. The feces of 211 children (76% under 5 years) were studied. Infection with diarrheagenic E. coli was detected in 12.3% of the samples. The pathotypes were EAEC (10.43%), ETEC (1.42%, all of them positive for thermolabile toxin), EPEC (0.95%) and STEC (0.47%, positive for Shiga toxin 2). The EAEC pathotype was prevalent in children of all age groups, while ETEC, EPEC and STEC were only observed in children under 5 years of age. This study constitutes the first report of diarrheagenic Escherichia coli detection in an outpatient pediatric population with diarrhea from La Plata, using molecular amplification techniques. Broader future studies, including the charac-terization of the isolates with the largest number of genes, asymptomatic controls, different times of the year and population from different geographic areas will be necessary to clarify the relevance of diarrheagenic E. coli infection in children from Argentina.

Nas infecções crônicas e recorrentes por Staphylococcus aureus, subpopulações de pequenas colônias (VCPSa) foram descritas. O objetivo desse trabalho foi reconhecer as características fenotípicas de VCPSa para otimizar sua detecção e caracterização a partir de materiais clínicos provenientes de infecções crônicas. Foram analisados n=3 VCPSa de pacientes adultos com infecções crônicas de tecidos moles. As amostras foram inoculadas em agar nutritivo, agar sangue; agar chocolate e agar Schaedler enriquecido. Foram realizados testes de coloração de Gram, catalase, coagulase livre, testes de dependência para hemina, menadiona e timidina, e desenvolvimento/fermentação do manitol em agar manitol salgado. A sensibilidade antibiótica foi realizada em agar Mueller Hinton suplementado, de acordo com os testes de dependência. Foi investigada a presença de proteína ligante de penicilina anômala (PBP2´) por aglutinação com látex. Os VCPSa foram detectados em meios de cultura enriquecidos. Estas bactérias deram positivas nos testes de catalase e coagulase positivos e eram dependentes de menadiona e hemina. A resistência à cefoxitina foi detectada nos três isolados e detectou-se a PBP2'.

In chronic and recurrent infections, small colonies of Staphylococcus aureus subpopulations (SCVSa) have been observed. The objective of the present study was to recognize the phenotypic characteristics of SCVSa isolated from patients with chronic infections to optimize their detection. SCVSa of adult patients n=3 with chronic soft tissue infections were analyzed. Samples were inoculated on nutritive agar, blood-agar, chocolate agar and supplemented Schaedler agar. Subsequently, Gram stain, catalase, free coagulase, dependence tests for hemin, menadione and thymidine, and growth/fermentation of mannitol on salt mannitol agar were performed. Antibiotic susceptibility tests were performed by the agar diffusion method on supplemented Mueller Hinton agar, according to dependence assays results. Anomalous penicillin binding protein (PBP2') was investigated by latex agglutination. SCVSa were detected in all enriched culture media. They showed catalase and coagulase activities, and menadione and hemin dependence. By the agar diffusion test, cefoxitin resistance was found in all isolates; PBP2' was detected as well.

En infecciones crónicas y recurrentes por Staphylococcus aureus se han descripto subpoblaciones de colonias pequeñas (VCPSa). El objetivo de este trabajo fue reconocer las características fenotípicas de VCPSa para optimizar su detección y caracterización a partir de materiales clínicos provenientes de infecciones crónicas. Se analizaron n=3 VCPSa de pacientes adultos con infecciones crónicas de tejidos blandos. Las muestras se inocularon en agar nutritivo, agar sangre, agar chocolate y agar Schaedler suplementado. Se realizaron tinción de Gram, catalasa, coagulasa libre, pruebas de dependencia para hemina, menadiona y timidina y, desarrollo/ataque del manitol en agar manitol salado. La sensibilidad antibiótica se efectuó en agar Mueller Hinton suplementado, según las pruebas de dependencia. Se investigó la presencia de proteína ligadora de penicilina anómala (PBP2´) por aglutinación con látex. Las VCPSa se detectaron en los medios de cultivo enriquecidos. Estas bacterias dieron positivas las pruebas de catalasa y coagulasa, y eran dependientes de menadiona y hemina. En los tres aislamientos se observó resistencia a cefoxitina y se detectó la PBP2´.

The aim of this study was to investigate the immunomodulatory properties of cell wall extract from Enterococcus faecalis CECT7121, measuring the induction of cytokines TNF-α, IL-6, IL-10 and IL-12 from human peripheral blood mononuclear cells (PBMCs). Cell wall extract was prepared from their growth in brain heart infusion broth (18 h, 35 °C). Subsequently, toxicity of the obtained cell wall extract was tested in Balb-C mice. PBMCs were isolated from buffy coats at the Blood Transfusion Service of Hospital Ramón Santamarina (Tandil, Argentina). PBMCs were purified using standard Ficoll-Paque gradient centrifugation. Aliquots of purified leukocytes were incubated at 37 °C for 24 h with heat-killed E. faecalis CECT7121 and cell wall extract. Concentrations of IL-6, TNF-α, IL-10 and IL-12 (p70) were measured by solid phase sandwich ELISA. Changes in appearance and behavior of mice were evidenced only in the group with the maximal concentration of wall cell extract used (10,000 μg). Cell wall extract and heat-killed E. faecalisCECT7121 induced the production of significantly higher amounts of Il-12, IL-6, TNF-α and IL-10 cytokines compared to the nonstimulated PBMCs. These findings provide helpful information on immunomodulation activity by cell wall extract in sight of the application of this compound in controlling certain infectious diseases.

En Enterococcus spp. aislados de quesos de oveja se investigó la resistencia in vitro a antimicrobianos de utilización clínica. Se determinó la concentración inhibitoria mínima (CIM) para gentamicina, estreptomicina, vancomicina, teicoplanina, ampicilina, imipenem, linezolid y tigeciclina. Se detectó la producción de β-lactamasa y se realizaron experimentos de conjugación para transferir resistencia a gentamicina. En un aislamiento de E. faecalis y en 10 de E. faecium se observó resistencia a ampicilina; se demostró la producción de β-lactamasa en un E. faecalis. En E. faecium, 15 aislamientos fueron resistentes a imipenem; 4 a linezolid y 5 a glucopéptidos. En 4 aislamientos de E. faecalis se demostró alto nivel de resistencia plasmídica a gentamicina. No se observaron aislamientos resistentes a tigeciclina. El queso de oveja es un reservorio de enterococos resistentes con potencial diseminación al hombre a través de la cadena alimentaria.

In vitro resistance to clinically used antimicrobials was investigated in Enterococcus spp. isolated from goat cheese. The gentamycin, streptomycin, vancomycin, teicoplanin, ampicillin, imipenem, linezolid and tigecyclin minimum inhibitory concentration (MIC) was determined. Β-lactamase production was detected and conjugation experiments were carried out for transferring gentamycin resistance. In one E. faecalis and in 10 E. faecium isolates there was ampicillin resistance and β-lactamase production was demonstrated in one E. faecalis. Fifteen E. faecalis were imipenenem resistant; 4 linezolid resistant and 5 glucopeptide resistant. There was a high level of plasmidic resistance to tigecyclin in 4 E. faecalis isolates. There were no tigecyclin resistant isolates. Goat cheese is a reservoir of resistant enterococci with potencial human dissemination through the food chain.

Investigou-se a atividade antimicrobiana da lama termal (Complejo Termal Copahue, Argentina) sobre microorganismos da microbiota autóctone do homem, agentes infecciosos da comunidade, hospitalares e cepas AT CC. As cepas corresponderam a cocos Gram positivos, bacilos Gram negativos, leveduras e cepas AT CC. A lama foi obtida da Laguna Sulfurosa. A atividade inibitória se demonstrou utilizando fase líquida (FL) mediante a prova de difusão em ágar e por estudos de cinética bactericida. Com a primeira se observou halo inibitório perante Staphylococcus aureus e Cándida albicans, não se visualizando inibição para o resto dos microorganismos. O estudo dinâmico através do tempo sobre S. aureus, Enterococcus faecalis, Staphylococcus epidermis e C. albicans demonstrou ação inibitória antes das 6 hs de incubação, enquanto não se observou inibição perante os bacilos Gram negativos. É o primeiro trabalho que demonstra a atividade antimicrobiana da FL sobre as cepas ensaiadas.

The antimicrobial activity of thermal mud from Copahue Thermal Complex against microorganisms from human microbiota, community and hospital infections agents and AT CC strains was investigated. Thermal mud samples were obtained from Sulfurous Lagoon located within the Complex. To determine the antimicrobial properties of the liquid phase (LP) of Copahue thermal mud we used in vitro assays, agar diffusion test and bactericidal rate, using gram-positive cocci, gram-negative bacilli, yeast and AT CC strains. Inhibition zones around the disk against Staphylococcus aureus and Candida albicans was showed with the first technique. No inhibition zones were observed for the rest of the microorganisms assayed. With the killing curve technique, inhibitory action before 6 h of incubation was observed against S. aureus, E. faecalis, S. epidermidis and C. albicans while there was no inhibition against gram negative bacillus. This is the first study that demonstrates the antimicrobial activity of LP on certain assayed strains.

Se investigó la actividad antimicrobiana del fango termal (Complejo Termal Copahue, Argentina) sobre microorganismos de la microbiota autóctona del hombre, agentes infecciosos de la comunidad, hospitalarios y cepas AT CC. Las cepas correspondieron a cocos Gram positivos, bacilos Gram negativos, levaduras y cepas AT CC. El fango se obtuvo de la Laguna Sulfurosa. La actividad inhibitoria se demostró utilizando fase líquida (FL) mediante la prueba de difusión en agar y por estudios de cinética bactericida. Con la primera se observó halo inhibitorio frente a Staphylococcus aureus y Cándida albicans, no visualizándose inhibición para el resto de los microorganismos. El estudio dinámico a través del tiempo sobre S. aureus, Enterococcus faecalis, Staphylococcus epidermis y C. albicans demostró acción inhibitoria antes de las 6 hs de incubación, mientras que no se observó inhibición frente a los bacilos Gram negativos. Es el primer trabajo que demuestra la actividad antimicrobiana de la FL sobre las cepas ensayadas.

This report describes two cases of cutaneous cellulitis in workers at the same poultry farm in the rural area of Tandil, Argentina. In both patients E. rhusiopathiae was identified from culture samples obtained through biopsy. Investigation of the reservoir showed that, in all samples of fowl waste and in 2 samples of feed, E. rhusiopathiae was isolated with identical biochemical and antibiotic resistance profiles to those of the isolated strains in the case reports. Even though molecular analyses are required to establish an epidemiologic relation between the strains found in the patients and those on the farm, it can be inferred that the source of human infection was the extensive poultry farm.

Se informan dos casos de celulitis cutánea en trabajadores de un mismo criadero de aves a corral del área rural de la ciudad de Tandil, Argentina. En ambos pacientes fue identificado E. rhusiopathiae a partir de cultivos de muestras obtenidas por biopsia. La investigación del reservorio evidenció que en todas las muestras de las excretas de aves y en dos muestras de los residuos del alimento, se aisló E. rhusiopathiae con idéntico perfil bioquímico y de resistencia antimicrobiana al de las cepas aisladas de los dos casos clínicos. Si bien son necesarios estudios moleculares para establecer la relación epidemiológica entre las cepas aisladas de los pacientes y las del criadero, se puede inferir que la fuente de infección humana fue el criadero extensivo de aves de corral.

The aim of the present paper was to evaluate the larvicidal effect of Enterococcus faecalis CECT7121 (Ef7121) on the Toxocara canis cycle both in vitro and in vivo. For the in vitro experiments, T. canis larvae were incubated with the supernatants of Ef7121 (EI) and mutant Ef7121 (EIm), in a pre-culture of Ef7121 (EII) and in a fresh culture with Ef7121 (EIII) and the Ef7121 mutant strain (EIIIm). The viability of the larvae was calculated after a 48 h incubation. A significant reduction of the viability of T. canis larvae was observed in EI, EII and EIII. A decrease of this inhibitory effect was observed in EIm and EIIIm (p = 0.008). In the in vivo experiments, mice were orally inoculated with three doses of Ef7121. To study the probiotic persistence in the intestine, the animals were sacrificed every four days and their intestines were dissected. The initial average bacterial levels were 9.7 x 10(4) for Ef7121 (colony forming units/g). At the end of the assay the levels were 1.46 x 10(4). No bacterial translocation was detected in mesenteric lymphatic nodules and spleen. Ef7121 interference with the biological cycle was evaluated in mice challenged with T. canis. The interference was significant when the mice were challenged with probiotic and T. canis simultaneously (p = 0.001), but it was not significant when the challenge was performed 15 days after administration of the bacterial inoculum (p = 0.06). In conclusion, Ef7121 possessed in vitro and in vivo larvicidal activity.