Patrones de adherencia en células HEp-2 de cepas de Escherichia coli aisladas de ríos contaminados de La Habana / Adherence patterns in HEp-2 cells of Escherichia coli strains isolated from contaminated rivers in Havana

Introducción: El proceso de adherencia es fundamental en el desarrollo de la mayoría de las infecciones ocasionadas por Escherichia coli. Para los patotipos de esta especie se describen tres patrones de adherencia diferentes: adherencia localizada, adherencia difusa y adherencia agregativa, los cuales se relacionan con los procesos patogénicos específicos que ocasiona en la clínica. Sin embargo, son pocos los estudios en relación con los fenotipos de adherencia in vitro de E. coli aisladas del ambiente. Objetivo: Determinar los fenotipos de adherencia de cepas de E. coli aisladas de ecosistemas dulceacuícolas de La Habana. Métodos: Se analizaron 108 cepas de E. coli aisladas de los ríos Almendares, Quibú y Luyanó de La Habana. Se determinó el patrón de adherencia mediante ensayos de adherencia en cultivo celular de la línea HEp-2 así como el serotipo de cada cepa. Resultados: El 25 por ciento de las cepas de E. coli aisladas fueron adherentes y el 75 por ciento fueron no adherentes. Veintidós cepas mostraron el típico patrón de adherencia difusa y cinco cepas mostraron una adherencia agregativa. Se encontraron cepas de los dos patrones de adherencia en los tres ríos evaluados. Las cepas presentaron 24 serotipos diferentes. Conclusiones: Se demostró que las cepas de E. coli ambientales circulantes en estos ecosistemas presentan características adherentes, cuya patogenicidad implica un riesgo potencial para la salud humana, especialmente en edades pediátricas(AU)

Introduction: Adherence is crucial to the development of most Escherichia coli infections. Three different adherence patterns have been described for pathotypes of this species: localized, diffuse and aggregative adherence, based on the specific clinical pathogenic processes they bring about. However, few studies have been conducted about in vitro adherence phenotypes of E. coli isolated from the environment. Objective: Determine the adherence phenotypes of E. coli strains isolated from freshwater ecosystems in Havana. Methods: An analysis was conducted of 108 E. coli strains isolated from the rivers Almendares, Quibú and Luyanó in Havana. Determination was made of the adherence pattern by adherence assays in HEp-2 cell line cultures, as well as of the serotype for each strain. Results: Of the E. coli strains isolated, 25 percent were adherent and 75 percent were not. Twenty-two strains displayed the typical diffusely adherent pattern and five displayed aggregative adherence. Strains exhibiting the two adherence patterns were found in the three rivers evaluated. The strains contained 24 different serotypes. Conclusions: The environmental E. coli strains circulating in these ecosystems were found to have adherent characteristics whose pathogenicity implies a potential risk to human health, particularly in childhood(AU)

Persistencia, internalización y translocación de Escherichia coli O157:H7, O157:H16 y O105ab en plantas y frutos de tomate (Solanum lycopersicum L.) / Persistence, internalization and translocation of Escherichia coli O157:H7, O157:H16 and O105ab in plants and tomato fruits (Solanum lycopersicum L.)

La presencia de bacterias patógenas, como Escherichia coli, afecta la calidad e inocuidad de las hortalizas que se consumen en fresco y se relaciona con graves problemas de salud. El objetivo de este trabajo fue determinar si 3 cepas diferentes de E. coli tienen la capacidad de penetrar y permanecer en plantas y frutos de tomate. Se siguió un diseño experimental completamente al azar, para lo cual se estableció un cultivo de tomate (variedad «Cid¼) en condiciones de invernadero y se evaluaron 3 tratamientos, T1 (E. coli O157: H7), T2 (E. coli de cultivo de tomate -#91;EcT-#93; O157: H16), T3 (E. coli de cultivo de espinaca -#91;EcH-#93; EcH O105ab) y un testigo T4, con 100 plantas cada uno y 4 formas de inoculación: en el sustrato, en el tallo, en el pecíolo y en el pedúnculo. Se realizaron muestreos en etapa vegetativa, floración, fructificación y madurez fisiológica para cuantificar en placa las UFC/g y saber si las bacterias lograban moverse y recuperarse en la raíz, el tallo, la flor y el fruto. Los grupos filogenéticos a los que correspondieron las bacterias recuperadas fueron confirmados mediante pruebas bioquímicas, serotipificación y PCR. A los 120 días la recuperación de bacterias en la planta fue del 23% (E. coli O157: H7), 28% (EcT O157: H16) y 55% (EcH O105ab) con la inoculación al sustrato, mientras que con la inoculación por punción la recuperación fue (en igual orden) del 5%, 3% y 4% a los 30 días; del 37%, 35% y 30% a los 90 días; y del 42%, 39% y 13% a los 65 días. Las cepas utilizadas mostraron la capacidad de entrar en la planta de tomate y de permanecer en ella y transportarse hasta llegar al fruto, sin producir síntomas que indiquen su presencia.

The presence of pathogenic bacteria, such as Escherichia coli affects the quality and safety of vegetables that are consumed fresh and is associated with serious health problems. The objective of this study was to determine if three different strains of E. coli can penetrate and remain in plants and tomato fruits. A completely randomized experimental design was followed for which a tomato crop ("Cid" variety) was established under greenhouse conditions and three treatments were evaluated, T1 (E. coli O157: H7), T2 (E. coli from tomato cultivation -#91;EcT-#93; O157: H16), T3 (E. coli from spinach cultivation -#91;EcH-#93; O105ab) and a T4 control, with 100 plants each and four forms of inoculation: in the substrate, steam, petiole and the peduncle. Samples were carried out in vegetative stage, flowering, fruiting and physiological maturity to quantify in petri dish CFU/g and know if the bacteria managed to move around and recover in root, stem, flower and fruit. The phylogenetic groups that corresponded to the bacteria recovered were confirmed by biochemical tests, serotyping and PCR. At 120 days the recovery of bacteria in the plant was 23% (E. coli O157: H7), 28% (EcT O157: H16) and 55% (EcH O105ab) whit inoculation to the substrate while the inoculation by puncture the recovery was (in the same order) of 5%, 3%, and 4% at 30 days; 37%, 35% and 30% at 90 days; and 42%, 39% and 13% at 65 days. The strains submit the ability to enter the tomato plant and to stay in it and transported to the fruit, without producing that indicate their presence.

Listeriosis en México: importancia clínica y epidemiológica / Listeriosis in Mexico: Clinical and epidemiological importance

La listeriosis es una enfermedad transmitida por alimentos (ETA) y ocasionada por Listeria monocytogenes. La importancia de ésta se debe a su impacto clínico, la alta tasa de mortalidad y el efecto económico derivado de los brotes asociados con el consumo de alimentos. En México, las fallas en los sistemas de vigilancia epidemiológicos son causa de información imprecisa sobre la incidencia de la listeriosis y sobre su caracterización como ETA. En este trabajo se presentan datos referentes a la presencia de la bacteria en alimentos, reportes de casos de la enfermedad y patologías relacionadas con infección por L. monocytogenes. La falta de datos exactos sobre la importancia de esta bacteria plantea la necesidad de concientizar a las instancias correspondientes para definir estrategias de búsqueda intencionada de L. monocytogenes en alimentos y de la recopilación de información clínica precisa que permita conocer la importancia clínica y epidemiológica de la listeriosis en México.

Listeriosis is caused by Listeria monocytogenes, an important food-borne disease due to its clinical forms, high mortality rate, and the economic impact in both clinical and food production industries. In Mexico, the lack of epidemiological surveillance systems leads to the need of accurate data on the incidence of listeriosis and its association with food-borne disease. In this paper, we present data about the presence of this bacterium in food, reports related to clinical cases of listeriosis, and information of diseases in which L. monocytogenes may be involved. However, in most of these cases the etiology was not established. Given this, there's a need to inform and warn the appropriate entities, to define strategies for the mandatory search of L. monocytogenes through the whole food production chain and clinical suspects, for the epidemiological importance and control of listeriosis in Mexico.

Susceptibilidad antimicrobiana de aislamientos de Escherichia coli procedentes de ecosistemas dulceacuícolas / Antimicrobial susceptibility of Escherichia coli isolates from river water ecosystems

Introducción: la resistencia antimicrobiana constituye uno de los mayores problemas que afronta la salud pública mundial. La aparición de cepas resistentes no solo de origen clínico sino también ambiental agrava la situación. Entre los microorganismos que presentan esta característica se destaca la especie bacteriana Escherichia coli debido a su doble papel como indicador de contaminación fecal y como patógeno. Objetivos: aislar e identificar hasta especie aislamientos de Escherichia coli a partir de muestras de agua procedentes de ríos contaminados de La Habana y determinar la susceptibilidad antimicrobiana in vitro de estos aislados. Métodos: se estudiaron 113 aislamientos de bacterias coliformes aislados de 10 estaciones de muestreo ubicadas en la zona urbana de los ríos capitalinos Almendares, Quibú y Luyanó en el período comprendido de febrero de 2008 hasta junio de 2010. La identificación de los aislados, la determinación de la susceptibilidad antimicrobiana y la búsqueda de b-lactamasas de espectro extendido se realizó mediante el método automatizado VITEK. Resultados: se identificaron 113 cepas ambientales de Escherichia coli. Se demostró que 23 % de los aislamientos resultaron resistentes al menos a uno de los antimicrobianos evaluados. Los mayores porcentajes de resistencia se observaron frente a ampicilina, sulfametoxazol-trimetropin y ciprofloxacina. Conclusiones: la presencia de aislados de E. coli con multirresistencia antimicrobiana en estos ríos indica claramente el riesgo biológico que implica el uso de sus aguas.

Introduction: antimicrobial resistance is one of the biggest problems facing global public health. The emergence of resistant clinical and environmental strains worsens the situation. Among the microorganisms with antimicrobial resistance, Escherichia coli species stands out due to its dual role as fecal contamination indicator and pathogen. Objectives: to isolate and identify Escherichia coli isolates from water samples from polluted rivers located in La Habana, and to determine their antimicrobial in vitro susceptibility. Methods: one hundred thirteen isolates of coliform bacteria isolated from 10 sampling stations in the capital´s urban areas near Almendares, Quibú and Luyanó rivers were studied in the period of February 2008 to June 2010. The identification of isolates, the determination of antimicrobial susceptibility and the search for extended-spectrum b-lactamase were all performed using VITEK automated method. Results: one hundred thirteen environmental strains of Escherichia coli were identified. It showed that 23 % of the isolates were resistant to at least one of the tested antimicrobials. The highest percentages of resistance were observed to ampicilline, sulfamethoxazole-trimethoprim and ciprofloxacin. Conclusions: the presence of E. coli isolates with multiple antimicrobial resistances in these rivers clearly indicates the biological risk involving the use of their waters.

Serogroups, K1 antigen, and antimicrobial resistance patterns of Aeromonas spp. strains isolated from different sources in Mexico

A total of 221 strains of Aeromonas species isolated in Mexico from clinical (161), environmental (40), and food (20) samples were identified using the automated system bioMérieux-Vitek®. Antisera for serogroups O1 to 044 were tested using the Shimada and Sakazaki scheme. The K1 antigen was examined using as antiserum the O7:K1C of Escherichia coli. Besides, we studied the antimicrobial patterns according to Vitek AutoMicrobic system. Among the 161 clinical strains 60 percent were identified as A. hydrophila, 20.4 percent as A. caviae, and 19.25 percent as A. veronii biovar sobria. Only A. hydrophila and A. veronii biovar sobria were found in food (55 and 90 percent respectively) and environmental sources (45 and 10 percent respectively). Using "O" antisera, only 42.5 percent (94/221) of the strains were serologically identified, 55 percent (121/221) were non-typable, and 2.5 percent (6/221) were rough strains. Twenty-two different serogroups were found, O14, O16, O19, O22, and O34 represented 60 percent of the serotyped strains. More than 50 percent of Aeromonas strain examined (112/221) expressed K1 encapsulating antigen; this characteristic was predominant among Aeromonas strains of clinical origin. Resistance to ampicillin/sulbactam and cephazolin was detected in 100 and 67 percent of Aeromonas strain tested for their susceptibility to antibiotics. In conclusion, antibiotic-resistant Aeromonas species that possess the K1 encapsulating antigen and represent serogroups associated with clinical syndrome in man are not uncommon among Aeromonas strains isolated from clinical, food and environmental sources in Mexico.

Serotypes of Vibrio cholerae non-O1 isolated from water supplies for human consumption in Campeche, México and their antibiotic susceptibility pattern

The presence of Vibrio cholerae non-O1 in water supplies for human consumption in the city of Campeche and rural locality of Becal was investigated. V. cholerae non-O1 was detected in 5.9 per cent of the samples obtained in deep pools of Campeche. Studies conducted in Becal and neighbourhood of Morelos in Campeche indicated that collected samples harbored V. cholerae non-O1 in 31.5 per cent and 8.7 per cent respectively. There was a particular pattern of distribution of V. cholerae non-O1 serotypes among different studied regions. Accordingly, V. cholerae non-O1 serotype O14 predominated in the deep pools of Campeche and together with V. cholerae non-O1, O155 were preferentially founds in samples taken from intradomiciliary faucets in the neighbourhood of Morelos. Samples from Becal predominantly presented the serotype O112. 60 per cent and 53.8 per cent of all studied strains of V. cholerae non-O1 proved to be resistant to amplicillin and carbenicillin. 3.1 per cent, 7.7 per cent and 6.2 per cent presented resistant to doxycycline, trimethroprim-sulfamethoxale and erythromycin respectively. The study showed the necessity of performing a strong epidemiologic surveillance for emergence and distribution of V. cholerae non-O1.