Synergistic effect of β-thujaplicin and tigecycline against tet(X4)-positive Escherichia coli in vitro / 生物工程学报

The widespread of tigecycline resistance gene tet(X4) has a serious impact on the clinical efficacy of tigecycline. The development of effective antibiotic adjuvants to combat the looming tigecycline resistance is needed. The synergistic activity between the natural compound β-thujaplicin and tigecycline in vitro was determined by the checkerboard broth microdilution assay and time-dependent killing curve. The mechanism underlining the synergistic effect between β-thujaplicin and tigecycline against tet(X4)-positive Escherichia coli was investigated by determining cell membrane permeability, bacterial intracellular reactive oxygen species (ROS) content, iron content, and tigecycline content. β-thujaplicin exhibited potentiation effect on tigecycline against tet(X4)-positive E. coli in vitro, and presented no significant hemolysis and cytotoxicity within the range of antibacterial concentrations. Mechanistic studies demonstrated that β-thujaplicin significantly increased the permeability of bacterial cell membranes, chelated bacterial intracellular iron, disrupted the iron homeostasis and significantly increased intracellular ROS level. The synergistic effect of β-thujaplicin and tigecycline was identified to be related to interfere with bacterial iron metabolism and facilitate bacterial cell membrane permeability. Our studies provided theoretical and practical data for the application of combined β-thujaplicin with tigecycline in the treatment of tet(X4)-positive E. coli infection.

Phylogenetic Group/Subgroups Distributions, Virulence Factors, and Antimicrobial Susceptibility of Escherichia coli Strains from Urinary Tract Infections in Hatay

Abstract INTRODUCTION: Nosocomial and community acquired urinary tract infections (UTIs) are one of the most encountered infections in the world. METHODS: This study aimed to determine the antibiotic susceptibility, phylogeny, and virulence genes of 153 Escherichia coli strains isolated from UTIs. Antimicrobial susceptibility of the isolates to different classes of antimicrobials was determined by the VITEK-2 automated system. Presence of virulence genes and phylogenetic groups were investigated by PCR. RESULTS: Regarding susceptibility to antimicrobials, ampicillin resistance was most abundant (67.3%), followed by amoxicillin-clavulanic acid (50.9%); least abundant was resistance to amikacin (1.3%) and nitrofurantoin (1.3%). Multi drug resistance (MDR) was observed in 34.6% of the isolates, and all isolates were found to be susceptible to imipenem, meropenem and fosfomycine. The majority of the isolates belonged to the phylogenetic group B23 (35.9%), followed by A1 (20.9%), D1 (18.9%), D2 (12.4%), A0 (%5.9), B1 (3.9%) and B2 (1.9%). Among E. coli strains examined, 49% had iucD, 32.7% papE-F, 26.1% papC, 15% cnf2, 11.1% sfa, 7.8% cnf1, 1.3% afaE, 1.3% afaD, 1.3% hlyA, 0.7% f17a-A, 0.7% clpG and 0.7% eaeA genes. CONCLUSIONS Our research demonstrated that virulence factors were distributed among different phylogroup/subgroups, which play a role in UTIs pathogenesis in humans. For this reason, complex and detailed studies are required to determine the relationship between virulence factors and specific E. coli strains that cause UTIs in humans.

Escherichia coli enterotoxigénica y enteroagregativa: prevalencia, patogénesis y modelos múridos / Enterotoxigenic and enteroaggregative Escherichia coli: prevalence, pathogenesis and murine models

Resumen Los patotipos de Escherichia coli enterotoxigénica (ETEC) y enteroagregativa (EAEC) son importantes agentes etiológicos causantes de diarrea en niños menores de cinco años de México y países en desarrollo, en quienes causan numerosas muertes. Ambos se han asociado con retraso en el crecimiento infantil y son los principales agentes causales de la "diarrea del viajero". La patogénesis de ambas bacterias se inicia cuando estas se adhieren al epitelio intestinal mediante fimbrias, denominadas factores de colonización en las cepas ETEC aisladas de humano y fimbrias de adherencia agregativa en las cepas de EAEC. Una vez que ETEC se adhiere al enterocito produce una o ambas de sus toxinas e induce la secreción de iones de cloruro, sodio y agua al lumen intestinal, produciendo su característica diarrea acusa. EAEC se une al epitelio intestinal formando una biopelícula, induce la producción de moco, libera sus toxinas y promueve inflamación. Modelos de infección de EAEC y ETEC con ratones C57BL/6 silvestres y deficientes del ligando de CD40 (con microbiotas intactas), respectivamente, revelaron que la desnutrición y la dieta baja en cinc incrementan la infección de EAEC causando retraso en el crecimiento y que ETEC coloniza, persiste e induce respuesta inmune humoral local y sistémica.

Abstract Enterotoxigenic (ETEC) and enteroaggregative Escherichia coli (EAEC) pathotypes are important etiological agents causative of diarrhea in children younger than 5 years of age in Mexico and in developing countries, where they cause numerous deaths. Both have been associated with delayed growth in children and are the main causative agents of traveler's diarrhea. The pathogenesis of both bacteria starts by adhering to the intestinal epithelium by means of fimbriae, called colonization factors in human ETEC isolates and aggregative adherence fimbriae in EAEC isolates. Once ETEC adheres to the enterocyte, it produces one or both of its toxins and induces the secretion of chloride and sodium ions and water into the intestinal lumen, producing its characteristic watery diarrhea. EAEC binds to the intestinal epithelium forming a biofilm, induces the production of mucus, releases its toxins and promotes inflammation. EAEC and ETEC infection models with wild-type C57BL/6 and CD40 ligand-deficient mice (with intact microbiota), respectively, revealed that undernutrition and low-zinc diet increases EAEC infection, causing growth retardation, and that ETEC colonizes, persists and induces local and systemic humoral immune response.

Genetic analysis of the first mcr-1 positive Escherichia coli isolate collected from an outpatient in Chile

ABSTRACT Global dissemination of mcr-like genes represents a serious threat to public health since it jeopardizes the effectiveness of colistin, an antibiotic used as a last-resort treatment against highly antibiotic-resistant bacteria. In 2017, a mcr-1-positive isolate of Escherichia coli was found in Chile for the first time. Herein we report the genetic features of this strain (UCO-457) by whole-genome sequencing (WGS) and conjugation experiments. The UCO-457 strain belonged to ST4204 and carried a 285 kb IncI2-type plasmid containing the mcr-1 gene. Moreover, this plasmid was transferred by conjugation to an E. coli J53 strain at high frequency. The isolate harbored the cma, iroN, and iss virulence genes and did carry resistance genes to trimethoprim/sulfamethoxazole and fluoroquinolones. Other antibiotic resistance determinants such as β-lactamases-encoding genes were not detected, making the isolate highly susceptible to these antibiotics. Our results revealed that such susceptible isolates could be acting as platforms to disseminate plasmid-mediated colistin resistance. Based on this evidence, we consider that mcr-like prevalence deserves urgent attention and should be examined not only in highly resistant bacteria but also in susceptible isolates.

Caracterização de Escherichia coli enteroagregativa entre crianças com diarreia na Amazônia ocidental brasileira / Characterization of enteroaggregative escherichia coli among diarrheal childrenin western brazilian amazon

ABSTRACT BACKGROUND: Enteroaggregative Escherichia coli (EAEC) is one of the main acute and chronic diarrhea causes both in children and adults, mainly in developing countries. OBJECTIVE: The aim of the present study is to characterize EAEC strains isolated from faecal samples and to identify genes potentially contributing to virulence, biofilm production and antimicrobial resistance in children admitted to a pediatric hospital in Porto Velho, Rondônia State. METHODS: The total of 1,625 E. coli specimens were isolated from 591 children in the age group 6 years or younger who were hospitalized in Cosme and Damião Children Hospital in Porto Velho, between February 2010 and February 2012, with acute gastroenteritis. Colonies suggestive of E. coli were subjected to polymerase chain reaction testing in order to identify the virulence factors. The in vitro adhesion assays using HEp-2 adherence were tests. Biofilm detection through spectrophotometry and antimicrobial susceptibility tests were conducted in the disk diffusion method. RESULTS: The mentioned study examined 591 stool samples from children with diarrhea. Diarrheogenic E. coli was found in 27.4% (162/591) of the children. EAEC was the diarreagenic E. coli most frequently associated with diarrhea 52.4% (85/162), which was followed by enteropathogenic E. coli 43.8% (71/162), enterotoxigenic E. coli 2.4% (4/162), and enterohemorrhagic E. coli 1.2% (2/162). The aggR gene was detected in 63.5% (54/85) of EAEC isolates; moreover, statistically significant correlation was observed among typical EAEC (aggR) and aatA (P<0.0001), irp2 (P=0.0357) and shf (P=0.0328). It was recorded that 69% (59/85) of the 85 analyzed EAEC strains were biofilm producers; 73% (43/59) of the biofilm producers carried the aggR gene versus 42.3% (11/26) of non-producers (P=0.0135). In addition, there was association between the aatA gene and biofilm production; 61% (36/59) of the samples presented producer strains, versus 19.2% (5/26) of non-producers (P<0.0004). Antibiotic sensitivity test evidenced that most EAEC were ampicillin 70.6% (60/85), sulfamethoxazole 60% (51/85), tetracycline 44.7% (38/85) and cefotaxime 22.4% (19/85) resistant. CONCLUSION: As far as it is known, the present study is pioneer in Northern Brazil to investigate EAEC virulence factors and to show the antimicrobial susceptibility of EAEC strains isolated from children with diarrhea.

RESUMO CONTEXTO: A Escherichia coli enteroagregativa (EAEC) é um dos principais agentes causadores de diarreia aguda e crônica em crianças e adultos, principalmente em países em desenvolvimento. OBJETIVO: Caracterizar cepas de EAEC isoladas de amostras fecais e identificar genes que potencialmente contribuem para a virulência, produção de biofilme e resistência antimicrobiana em crianças internadas em um hospital pediátrico em Porto Velho, Rondônia. MÉTODOS: Um total de 1.625 cepas de E. coli foram isolados de 591 crianças com gastroenterite aguda na faixa etária de 6 anos que foram internadas no Hospital Infantil Cosme e Damião na cidade de Porto Velho, entre fevereiro de 2010 e fevereiro de 2012. Colônias sugestivas de E. coli foram submetidas a reação em cadeia da polimerase para identificação de fatores de virulência. O ensaio de adesão in vitro foi desenvolvido com célula HEp-2. A detecção de biofilme foi realizada através do teste de espectrofotometria e os testes de susceptibilidade aos antimicrobiana foram realizados através do método de difusão em disco. RESULTADOS: A E. coli diarreiogênica foi encontrada em 27,4% (162/591) das crianças e a EAEC foi a E. coli diarreiogênica mais frequentemente associada à diarreia com 52,4% (85/162), seguida pela E. coli enteropatogênica 43,8% (71/162), E. coli enterotoxigênica 2,4% (4/162) e E. coli enterohemorrágica 1,2% (2/162). O gene aggR foi detectado em 63,5% (54/85) dos isolados de EAEC com correlação estatisticamente significante entre esse gene com os genes aatA (P<0,0001), irp2 (P=0,0357) e shf (P=0,0328). Neste estudo 69% (59/85) das cepas de EAEC eram produtoras de biofilme, destas 73% (43/59) possuíam o gene aggR, ao passo que entre as não produtoras 42,3% (11/26) possuíam o gene (P=0,0135). Essa associação também foi observada com o gene aatA, presente em 61% (36/59) das cepas produtoras e em 19,2% (5/26) das não produtoras (P<0,0004). O teste de sensibilidade aos antibimicrobianos evidenciou que a maioria das EAEC eram resistentes a ampicilina 70,6% (60/85), ao sulfametoxazol 60% (51/85), a tetraciclina 44,7% (38/85) e a cefotaxima 22,4% (19/85). CONCLUSÃO: Este é o primeiro estudo no Norte do Brasil sobre a investigação dos fatores de virulência de EAEC mostrando a susceptibilidade antimicrobiana de cepas de EAEC isoladas de crianças com diarreia.

Detección y caracterización de Escherichia coli productor de toxina Shiga en ninos atendidos en un hospital pediátrico interzonal de la ciudad de La Plata / Detection and characterization of Shiga toxin-producing Escherichia coli in children treated at an inter-zonal pediatric hospital in the city of La Plata

Escherichia coli productor de toxina Shiga (STEC) es un patógeno transmitido por alimentos que puede causar diarrea acuosa, diarrea sanguinolenta (DS) y síndrome urémico hemolítico (SUH). El objetivo de este estudio fue determinar las características fenotípicas y genotípicas de cepas STEC aisladas de niños con DS y SUH atendidos en un hospital pediátrico de la ciudad de La Plata en el período 2006-2012 y establecer la relación clonal de los aislamientos O157: H7 mediante electroforesis de campo pulsado. El porcentaje de muestras positivas fue de 4,9 y 39,2% en los pacientes que presentaron DS y SUH, respectivamente. Se aislaron 77 cepas STEC de 10 serotipos distintos, con el 100% de recuperación de colonias. El serotipo más frecuente fue O157: H7 (71,4%), seguido por O145: NM (15,6%). El 98,2% de los aislamientos O157: H7 correspondió al biotipo C y fue sensible a los antibióticos ensayados. Todos esos aislamientos presentaron el genotipo stx2, eae, fliC H7, ehxA, iha, efa, toxB, lpfA1-3 y lpfA2-2.Al estudiar la relación clonal de las cepas O157: H7, se identificaron un total de 42 patrones con al menos un 88% de similitud y se establecieron 6 clústeres que agruparon cepas con perfiles idénticos. Los aislamientos eae negativos pertenecieron a los serotipos O59: H19, O102: H6, O174: NM y O174: H21. Las cepas O59: H19 y O174: H21 fueron positivas para el gen aggR. Este estudio muestra que en la ciudad de La Plata y alrededores circulan STEC de diferentes serotipos y genotipos. A pesar de la diversidad genética observada entre los aislamientos O157: H7, algunos fueron indistinguibles por las técnicas de subtipificación utilizadas.

Shiga toxin-producing Escherichia coli (STEC) is a foodborne pathogen that can cause watery diarrhea, bloody diarrhea (BD), and hemolytic uremic syndrome (HUS). The objective of this study was to determine the phenotypic and genotypic profiles of STEC strains isolated from children with BD and HUS treated at a pediatric hospital in the city of La Plata in the period 2006-2012, and to establish the clonal relationship of O157: H7 isolates by pulsed field electrophoresis. The percentage of positive samples was 4.9% and 39.2% in patients with BD and HUS, respectively. Seventy-seven STEC strains from 10 different serotypes were isolated, with 100% colony recovery, O157: H7 being the most frequent (71.4%) serotype, followed by O145: NM (15.6%). An average of 98.2% of O157: H7 isolates belonged to biotype C and were sensitive to all the antibiotics tested. All of them (100%) carried genotype stx2, eae, fliC H7, ehxA, iha, efa, toxB, lpfA1-3 and lpfA2-2. When the clonal relationship of the O157: H7 strains was studied, a total of 42 patterns with at least 88% similarity were identified, and 6 clusters with identical profiles were established. The eae-negative isolates belonged to serotypes O59: H19, O102: H6, O174: NM and O174: H21. The strains O59: H19 and O174: H21 were positive for the aggR gene. This study shows that STEC of different serotypes and genotypes circulate in the city of La Plata and surroundings. Despite the genetic diversity observed between the O157: H7 isolates, some were indistinguishable by the subtyping techniques used.

pMEX01, a 70kb Plasmid Isolated From Escherichia Coli That Confers Resistance to Multiple ß-Lactam Antibiotics

Abstract Multidrug-resistant microorganisms are of great concern to public health. Genetic mobile elements, such as plasmids, are among the most relevant mechanisms by which bacteria achieve this resistance. We obtained an Escherichia coli strain CM6, isolated from cattle presenting severe diarrheic symptoms in the State of Querétaro, Mexico. It was found to contain a 70 kb plasmid (pMEX01) with a high similarity to the pHK01-like plasmids that were previously identified and described in Hong Kong. Analysis of the pMEX01 sequence revealed the presence of a blaCTX-M-14 gene, which is responsible for conferring resistance to multiple β-lactam antibiotics. Several genes putatively involved in the conjugative transfer were also identified on the plasmid. The strain CM6 is of high epidemiological concern because it not only displays resistance to multiple β-lactam antibiotics but also to other kinds of antibiotics.

Evaluación de susceptibilidad y respuesta al tratamiento con piperacilina/tazobactam en pacientes con infecciones por Escherichia coli productoras de β -lactamasas de espectro extendido (BLEE) CTX-M / Evaluation of susceptibility and response to therapy with piperacillin-tazobactam in patients with infections caused by Escherichia coli with extended-spectrum β -lactamase (ESBL) CTX-M

Resumen Introducción: En las infecciones por enterobacterias productoras de β-lactamasas de espectro extendido (BLEE), los β-lactámicos preferidos para tratamiento son los carbapenémicos. Sin embargo, estudios clínicos muestran eficacia de piperacilina/tazobactam en ciertas infecciones por Escherichia coli productoras de BLEE. Objetivo: Determinar la cura clínica y microbiológica con piperacilina/tazobactam en pacientes con infecciones por E. coli productoras de BLEE, tipo CTX-M. Materiales/Métodos: Estudio descriptivo, retrospectivo, con adultos internados en un hospital universitario. Incluimos infecciones del tracto urinario (ITU), intra-abdominales (IIA) e infecciones de tejidos blandos (ITB). Resultados: Estudiamos 40 pacientes, donde 65% correspondían a ITU, 25% IIA y 10 % ITB. La cura clínica global se logró en 89,4%, con mejores resultados en las ITU (100%), seguidas de ITB (80%) e IIA (70%). El 85% de las cepas tenía concentraciones inhibitorias mínimas (CIM) ≤ 8 μg/mL y 70% con CIM ≤ 4 μg/mL. La tasa de fracaso fue mayor en las infecciones con inóculos altos intraabdominales. La BLEE del tipo CTX-M-15 se encontró en 62,5%. Conclusiones: Piperacilina/tazobactam logró cura clínica y microbiológica, en pacientes con infecciones por E. coli productoras de BLEE susceptibles, especialmente en ITU e IPB y en menor medida en IIA.

Background: Carbapenems are the preferred β-lactamics for treatment for infections caused by enterobacteria producing extended-spectrum β-lactamases (ESBL); however, clinical studies show effectiveness of piperacillin/tazobactam in certain infections by Escherichia coli ESBL producers. Aim: To determine the clinical and micro-biological cure with piperacillin/tazobactam in patients with infections caused by E. coli ESBL producers, CTXM type. Methods: Retrospective descriptive study with adults hospitalized in a university hospital. We included urinary tract infections (UTI), intra-abdominal infections (IAI), soft tissue infections (STI) and/or bacteremia. Results: We studied 40 patients, where 65% corresponded to UTI, 25% to IAI and 10% were STI. The overall clinical cure was achieved in 89.4%, with the best results in the ITU (100%), followed by STI (80%) and 70% in IAI. The 85% of the strains had minimum inhibitory concentrations (MIC) ≤8 μg/ml and 70% with MIC ≤4 μg/mL, however the rate of failure were high in intra-abdominal infections with high inocula or not controlled; CTX-M-15 was found in the 62.5%. Conclusions: Piperacillin/tazobactam was efficient to obtain clinical and microbiological cure in patients with infections caused by ESBL producers but susceptible E. coli, especially in UTI and STI and to a lesser extent in IAI.

Primera comunicación en Chile de la detección del gen mcr-1 en un aislado clínico de Escherichia coli resistente a colistín / First report in Chile of a clinical isolate of Escherichia coli resistant to colistin harbouring the mcr-1 gene

Recently it was described the plasmidial gene mcr-1 associated with colistin resistance. We screened by PCR and sequencing for gene mcr-1 in thirteen clinical isolates resistant to colistin. We observed amplification in one E. coli. To our knowledge, this is the first report of the presence of mcr-1 gene in Chile.

Sensibilidad a fosfomicina en Escherichia coli productoras de betalactamasas de espectro extendido / Sensitivity to Fosfomycin in Extended-spectrum Betalactamase-producing Escherichia coli

RESUMEN Las infecciones urinarias son causadas mayormente por Escherichia coli (E. coli), el uso indiscriminado de antibióticos ha originado un aumento de infecciones por cepas productoras de betalactamasas de espectro extendido (BLEE). Con el objetivo de determinar la sensibilidad a fosfomicina se realizó un estudio en cepas de E. coli productoras de BLEE aisladas de urocultivos provenientes de un hospital de Perú. Se recolectaron 266 cepas de E. coli identificadas por métodos convencionales como productoras de BLEE. Se determinó la sensibilidad de fosfomicina por concentración inhibitoria mínima mediante el método de dilución en agar y por el método de disco difusión. Se encontró 192 (72,2 %) cepas de E. coli productora de BLEE sensibles a fosfomicina. Se concluye que la fosfomicina presenta actividad antimicrobiana frente a cepas de E. coli productoras de BLEE, y podría ser considerada una buena opción terapéutica frente a cepas resistentes.

ABSTRACT Urinary infections are caused mainly by Escherichia coli (E. coli); indiscriminate use of antibiotics has caused an increase in infections due to extended-spectrum beta-lactamase (ESBL)-producing strains. Aiming to determine the sensitivity to fosfomycin, a study was conducted in ESBL-producing E. coli strains isolated from urine cultures at a hospital in Peru. Two hundred and sixty-six (266) strains of E. coli were collected, which were determined by conventional methods to be ESBL- producing. Sensitivity to fosfomycin was determined through minimum inhibitory concentration with the agar dilution method and the diffusion disc method. One hundred and ninety-two (192) (72.2%) strains of ESBL-producing E. coli strains sensitive to Fosfomycin were found. It, therefore, follows that fosfomycin exhibits antimicrobial activity against ESBL-producing E. coli strains and that it could be considered a good treatment option for resistant strains.

Characterization of avian pathogenic Escherichia coli isolated from free-range helmeted guineafowl

Abstract Avian pathogenic Escherichia coli (APEC) isolates from apparently healthy free range helmeted guineafowl were characterized. Most of them had a high frequency of virulence associated genes, multi drug resistance and high pathogenicity. We demonstrated that helmeted guineafowl have potential to transmit antibiotic resistant APEC to other species including humans.

Survey on pathogenic Escherichia coli and Salmonella spp. in captive cockatiels (Nymphicus hollandicus)

Abstract We surveyed healthy captive cockatiels (Nymphicus hollandicus) for Escherichia coli and Salmonella spp. Cloacal swabs were collected from 94 cockatiels kept in commercial breeders, private residencies and pet shops in the cities of São Paulo/SP and Niterói/RJ (Brazil). Three strains of E. coli from each individual were tested for the presence of ExPEC-, APEC- and DEC-related genes. We evaluated the blaTEM, blaSHV, blaOXA, blaCMY, blaCTX-M, tetA, tetB, aadA, aphA, strAB, sul1, sul2, sul3, qnrA, qnrD, qnrB, qnrS, oqxAB, aac (6)′-Ib-cr, qepA resistance genes and markers for plasmid incompatibility groups. Salmonella spp. was not detected. E. coli was isolated in 10% of the animals (9/94). Four APEC genes (ironN, ompT, iss and hlyF) were detected in two strains (2/27-7%), and iss (1/27-4%) in one isolate. The highest resistance rates were observed with amoxicillin (22/27-82%), ampicillin (21/27-79%), streptomycin (18/27-67%), tetracycline (11/27-41%). Multiresistance was verified in 59% (16/27) of the isolates. We detected strAB, bla TEM, tetA, tetB, aadA, aphaA, sul1, sul2, sul3 resistance genes and plasmid Inc groups in 20 (74%) of the strains. E. coli isolated from these cockatiels are of epidemiological importance, since these pets could transmit pathogenic and multiresistant microorganisms to humans and other animals.

Caracterización molecular y patrón de susceptibilidad antimicrobiana de Escherichia coli productora de β -lactamasas de espectro extendido en infección del tracto urinario adquirida en la comunidad / Molecular characterization and antimicrobial susceptibility pattern of extended-spectrum β -lactamase-producing Escherichia coli as cause of community acquired urinary tract infection

Resumen Introducción Las infecciones del tracto urinario adquiridas en la comunidad (ITUac) causadas por cepas de Escherichia coli productoras de β-lactamasas de espectro extendido (BLEE), principalmente por cepas que contienen el gen blaCTX-M-15, es un fenómeno creciente a nivel mundial. Objetivo Determinar el patrón de susceptibilidad a antimicrobianos de cepas de E. coli productoras de BLEE causantes de ITUac y conocer su patrón molecular. Materiales y Métodos Se realizó un estudio descriptivo en Oaxaca, México, donde se incluyeron 288 cepas de E. coli aisladas de pacientes adultos con posible ITUac. Para obtener los patrones de susceptibilidad antimicrobiana se siguieron los criterios del CLSI y para obtener el análisis molecular se utilizó la técnica de RPC. Resultados Del total de cepas de E. coli aisladas, 31,3% fueron productoras de BLEE, presentando una menor susceptibilidad a antimicrobianos que las cepas no productoras de estas enzimas. El 95,6% de las cepas BLEE estudiadas fueron portadoras del gen blaCTX-M. Conclusiones Un tercio de las ITUac causadas por E. coli en nuestra población fueron causadas por cepas BLEE, mostrando un alto nivel de resistencia a los antimicrobianos comúnmente utilizados en su tratamiento y disminuyendo las opciones terapéuticas para tratamientos empíricos en esta población.

Background Community acquired urinary tract infections (CaUTI) caused by strains of extended-spectrum β-lactamases (ESBL) - producing Escherichia coli, mainly by strains carrying the blaCTX-M-15 gene, is a growing phenomenon worldwide. Aim To determine the antibiotic susceptibility pattern of ESBL-producing E. coli as cause of CaUTI and to identify their molecular pattern. Methods A descriptive study was performed in the city of Oaxaca, Mexico, from where 288 strains of CaUTI-producing strains of E. coli in adults with possible UTI were isolated. The CLSI criteria was followed to determine the antimicrobial susceptibility patterns, and their molecular characterization was performed by using PCR. Results 31.3% of E. coli strains isolated in our population were ESBL producers, which presented higher levels of antibiotic resistance than those of non-producers of these enzymes. 95.6% of the studied strains were carriers of the blaCTX-M gene. Conclusions One-third of the Ca-UTI caused by E. coli in our population are caused by ESBL-producing strains, which present high levels of resistance to the antibiotics widely used in our community. This situation considerably decreases the number of antibiotics available for an empiric treatment against these infections.

Clinical characterization and antimicrobial resistance of Escherichia coli in pediatric patients with urinary tract infection at a third level hospital of Quito, Ecuador / Caracterización clínica y resistencia antimicrobiana de Escherichia coli en pacientes pediátricos con infección del tracto urinario en un hospital de tercer nivel en Quito, Ecuador

Abstract: Background: Urinary tract infections (UTI) are among the most common infections in pediatric patients. The main etiopathogenic agent is Escherichia coli. The purpose of this study was to determine the antimicrobial resistance pattern of E. coli in pediatric patients and to understand their main clinical and laboratory manifestations. Methods: Fifty-nine patients were included in the study and classified into two groups: hospitalization (H) and external consultation (EC). Every patient presented urine cultures with the isolation of E. coli that included an antibiogram. Clinical signs and symptoms, urinalysis, complete blood count (CBC) and serum inflammatory markers were analyzed. Results: The most common clinical manifestations were fever (H: 76.5%; EC: 88%), vomiting (H: 32.4%; EC: 32%), hyporexia (H: 20.6%; EC: 16%), abdominal pain (H: 20.6%: EC: 28%), and dysuria (H: 14.7%; EC: 32%). Ten patients (16.95%) presented UTI for extended spectrum beta-lactamase (ESBL) E. coli. Ampicillin, nalidixic acid, and trimethoprim-sulfamethoxazole showed a higher resistance rate, being ampicillin the most significant (H: 88.2%; EC: 92%). Leukocyturia, bacteriuria and urine nitrites were frequent alterations in urinalysis (H: 52.9%; EC: 92%). In ESBL E. coli patients, a positive correlation was found between leukocytes in CBC and C-reactive protein (r = 0.9, p < 0.01). Diarrhea and foul-smelling urine were associated with E. coli resistance. Conclusions: The presence of leukocytes, bacteria, nitrites and the Gram stain are the most common indicators. Nitrofurantoin and phosphomycin are good therapeutic options. However, an antibiogram must be conducted to determine the best therapeutic agent.

Resumen: Introducción: Las infecciones de tracto urinario (ITU) se encuentran entre las más frecuentes en pediatría, siendo Escherichia coli el principal agente etiopatogénico. El objetivo de este estudio fue determinar el patrón de resistencia antimicrobiana de E. coli en pacientes pediátricos y conocer sus principales manifestaciones clínicas y de laboratorio. Métodos: Se incluyeron en el estudio 59 pacientes en dos grupos: hospitalización (H) y consulta externa (CE). En cada uno se realizó un urocultivo y un antibiograma con aislamiento de E. coli. Se analizaron signos y síntomas, uroanálisis, hemograma y marcadores séricos de inflamación. Resultados: Las manifestaciones clínicas más frecuentes fueron fiebre (H: 76.5%; CE: 88%), vómito (H: 32.4%; CE: 32%), hiporexia (H: 20.6%; CE: 16%), dolor abdominal (H: 20.6%: CE: 28%) y disuria (H: 14.7%; CE: 32%). Diez pacientes (16.95%) presentaron ITU por E. coli beta-lactamasa de espectro extendido (BLEE). La ampicilina, ácido nalidíxico y trimetroprim con sulfametoxazol mostraron alta resistencia, siendo ampicilina la más significativa (H: 88.2%, CE: 92%). Leucocituria, bacteriuria y nitritos en orina fueron frecuentes en el uroanálisis. En pacientes con E. coli BLEE se encontró una correlación positiva entre los leucocitos y la proteína C reactiva (r = 0.9, p < 0.01). La diarrea y el mal olor en la orina se asociaron con resistencia de E. coli. Conclusiones: La leucocituria, la bacteriuria, los nitritos y la tinción Gram son los indicadores más frecuentes de ITU. La nitrofurantoina y fosfomicina son buenas opciones terapéuticas. Sin embargo, debe realizarse un antibiograma para determinar el mejor tratamiento.

Microbiological and serological control of Escherichia coli O157: H7 in kindergarten staff in Buenos Aires city and suburban areas

Shiga toxin (Stx)-producing Escherichia coli (STEC) infections are implicated in the development of the life-threatening hemolytic-uremic syndrome (HUS). Despite the magnitude of the social and economic problems caused by HUS, no licensed vaccine or effective therapy is currently available for human use. Prevention of STEC infections continues being the most important measure to reduce HUS incidence. This is especially true for Argentina where HUS incidence among children is extremely high and shows an endemic pattern. The aim of this work was to investigate serologically adult staff of kindergartens in Buenos Aires city and suburban areas in order to detect possible carriers, and to educate personnel about good practices to reduce HUS transmission. We also assessed the microbiological quality of water and meal samples from the same kindergartens. We tested 67 healthy adults, 13 water supplies and 6 meals belonging to 6 public kindergartens. We analysed hand swabs for isolation of STEC and serum samples for the presence of antibodies against Stx and lipopolysaccharide (LPS) of O157 serogroup. We identified 46 Stx2-positive individuals, but only 7 for O157 LPS. No presence of STEC pathogens was detected in hands of staff, water or meal samples.

Las infecciones bacterianas con Escherichia coli productor de toxina Shiga (Stx) (STEC) están implicadas en el desarrollo del síndrome urémico hemolítico (SUH). A pesar de la magnitud del problema social y económico causado por el SUH, actualmente no existe un tratamiento específico o una vacuna eficaz para uso humano. Por lo tanto, la prevención de las infecciones por STEC es la tarea central para reducir la incidencia del SUH. Esto es especialmente cierto para Argentina en donde el SUH muestra un comportamiento endémico y presenta una incidencia extremadamente alta entre los niños. En efecto, la mediana de casos notificados en menores de 5 años para el periodo 2010-2015 fue 306, mientras que la tasa de notificación fue 8.5 casos cada 100 000 menores/año (http://www.msal.gob.ar/images/stories/boletines/boletin_integrado_vigilancia_N335-SE45.pdf). El objetivo de este trabajo fue analizar serológicamente al personal adulto de jardines de infantes de la ciudad de Buenos Aires y el área suburbana con el fin de detectar portadores, y brindarles formación sobre las buenas prácticas para reducir la transmisión de infecciones con STEC y así evitar el SUH. También se evaluó la calidad microbiológica de las muestras de agua y de la comida elaborada en los mismos jardines. Hemos estudiado 67 adultos, a través del hisopado de manos para la búsqueda de STEC y suero para la presencia de anticuerpos contra Stx y el lipopolisacárido (LPS) de serogrupo O157. También se analizaron 13 suministros de agua y 6 muestras de comida pertenecientes a 6 jardines de infantes públicos. Se identificaron 46 individuos positivos para Stx2, pero solo 7 para LPS-O157. No se detectó presencia de patógenos STEC en las muestras de las manos del personal, ni en los reservorios de agua o muestras de comida.

Ex vivo model of rabbit intestinal epithelium applied to the study of colonization by enteroaggregative escherichia coli / Modelo ex vivo de epitélio intestinal de coelho aplicado ao estudo de colonização por Escherichia coli enteroagregativa

ABSTRACT BACKGROUND The diarrheal syndrome is considered a serious public health problem all over the world and is considered a major cause of morbidity and mortality in developing countries. The high incidence of enteroaggregative Escherichia coli in diarrheal syndromes classified as an emerging pathogen of gastrointestinal infections. After decades of study, your pathogenesis remains uncertain and has been investigated mainly using in vitro models of adhesion in cellular lines. OBJECTIVE The present study investigated the interaction of enteroaggregative Escherichia coli strains isolated from childhood diarrhea with rabbit ileal and colonic mucosa ex vivo, using the in vitro organ culture model. METHODS The in vitro adhesion assays using cultured tissue were performed with the strains co-incubated with intestinal fragments of ileum and colon over a period of 6 hours. Each strain was tested with three intestinal fragments for each region. The fragments were analysed by scanning electron microscopy. RESULTS Through scanning electron microscopy we observed that all strains adhered to rabbit ileal and colonic mucosa, with the typical aggregative adherence pattern of “stacked bricks” on the epithelium. However, the highest degree of adherence was observed on colonic mucosa. Threadlike structures were found in greater numbers in the ileum compared to the colon. CONCLUSION These data showed that enteroaggregative Escherichia coli may have a high tropism for the human colon, which was ratified by the higher degree of adherence on the rabbit colonic mucosa. Finally, data indicated that in vitro organ culture of intestinal mucosa from rabbit may be used to elucidate the enteroaggregative Escherichia coli pathogenesis.

RESUMO CONTEXTO A síndrome diarréica é considerada um grave problema de saúde pública em todo o mundo e é considerada uma das principais causas de morbidade e mortalidade nos países em desenvolvimento. A elevada incidência de Escherichia coli enteroagregativa nas síndromes diarreicas a classificou como um patógeno emergente de infecções gastrintestinais. Depois de décadas de estudo, sua patogênese ainda é incerta e tem sido investigada usando principalmente modelos in vitro de adesão em linhagens celulares. OBJETIVO O presente estudo investigou a interação de cepas de Escherichia coli enteroagregativa isoladas de diarreia infantil com mucosa ileal e colônica de coelho ex vivo, utilizando o modelo de cultura de órgão in vitro. MÉTODOS Os ensaios de adesão in vitro utilizando tecido cultivado foram realizados com as cepas co-incubadas com fragmentos intestinais de íleo e de cólon durante um período de 6 horas. Cada cepa foi testada em três fragmentos intestinais para cada região. Os fragmentos foram analisados por microscopia eletrônica de varredura. RESULTADOS Através da microscopia eletrônica de varredura observamos que todas as cepas aderiram a mucosa ileal e colônica de coelho, com o padrão de aderência agregativo típico de “tijolos empilhados” no epitélio. Entretanto, o maior grau de adesão foi observado na mucosa do cólon. Estruturas filiformes foram encontradas em maior número no íleo em comparação com o cólon. CONCLUSÃO Esses dados mostraram que Escherichia coli enteroagregativa pode ter um maior tropismo para o cólon humano, o que foi ratificado pelo maior grau de aderência na mucosa do cólon de coelho. Finalmente, os dados indicaram que a cultura de órgão in vitro da mucosa intestinal de coelho pode ser utilizado para elucidar a patogênese de Escherichia coli enteroagregativa.

Diarrheagenic Escherichia coli

ABSTRACT Most Escherichia coli strains live harmlessly in the intestines and rarely cause disease in healthy individuals. Nonetheless, a number of pathogenic strains can cause diarrhea or extraintestinal diseases both in healthy and immunocompromised individuals. Diarrheal illnesses are a severe public health problem and a major cause of morbidity and mortality in infants and young children, especially in developing countries. E. coli strains that cause diarrhea have evolved by acquiring, through horizontal gene transfer, a particular set of characteristics that have successfully persisted in the host. According to the group of virulence determinants acquired, specific combinations were formed determining the currently known E. coli pathotypes, which are collectively known as diarrheagenic E. coli. In this review, we have gathered information on current definitions, serotypes, lineages, virulence mechanisms, epidemiology, and diagnosis of the major diarrheagenic E. coli pathotypes.