Occurrence of Aliarcobacter spp. in fresh and pre-cut vegetables of common use in San José, Costa Rica.

Aliarcobacter is a Gram-negative rod that can cause disease in both animals and humans. Several studies have evidenced its presence in a wide variety of foods. Given that the number of foodborne illness outbreaks linked to the consumption of vegetables has increased worldwide and that there is a lack of information about the occurrence of Aliarcobacter spp. in these, the aim of this study was to evaluate its presence and the occurrence of virulence factors in both fresh and ready-to-eat vegetable samples. 180 vegetable samples from Costa Rica were analyzed for the presence of Aliarcobacter spp., including 90 pre-cut vegetable packages and 90 fresh vegetables. Two (2.2%) of the isolates from pre-cut vegetables and 19 (21.1%) of the isolates obtained from fresh vegetables were confirmed as Aliarcobacter spp. One of the isolates from the pre-cut vegetable samples was identified as A. butzleri. For the fresh vegetables, 11 isolates were identified as A. skirrowii, one as A. butzleri, and the 7 remaining isolates could not be identified at a species level. There is an 87.5% positivity for hecA and 93.8% for pldA, virulence genes in strains isolated from fresh produce, contrasting with an absolute absence from pre-cut vegetable-isolated strains. These results evidence the presence of Aliarcobacter on fresh and pre-cut vegetables from Costa Rica and the potential hazard it might represent for public health.

Efecto de la actividad truchícola sobre la concentración de coliformes totales y Escherichia coli en aguas de la cuenca alta del río Savegre, Costa Rica

Introducción: La acuacultura de truchas ha incrementado gradualmente en las tierras altas de Costa Rica. Las aguas residuales de esta actividad son descartadas directamente en los ríos, sin tratamientos previos. Como consecuencia, la actividad truchícola puede contaminar severamente el agua de los ríos con bacterias que pueden afectar la salud humana. Objetivo: Evaluar la contaminación bacteriana por la acuacultura de truchas en el río Savegre, Costa Rica. Métodos: Contamos los coliformes totales y Escherichia coli de muestras mensuales (2015-2018) en tres secciones del proyecto de acuacultura más grande de la cuenca alta del río. Recolectamos las muestras en la entrada de los estanques para las truchas, a la salida, y 200 m hacia abajo. Resultados: Encontramos menos coliformes totales y E. coli en el agua recolectada justo en la salida del agua de los estanques. El número de coliformes totales fue mayor en el 2016 y 2017, y de E. coli en el 2016. Conclusiones: Conteos de coliformes y de E. coli es muy alto en el río, pero inesperadamente, su número disminuye en el agua residual descartada de los estanques. Podría ser que el mucus producido por las truchas o sustancias liberadas del musgo que cubre la pared de los estanques reduzca el crecimiento de bacterias, como se ha sido sugerido en otros estudios. La contaminación del río parece venir de otras fuentes.

Introduction: The trout aquacultural activity has gradually increased in Costa Rican highlands. Residual waters from this activity are discarded directly in the rivers without any previous treatment process. Consequently, this activity could severely contaminate the river with bacteria that can affect human health. Objective: To evaluate bacterial contamination from trout aquaculture on Río Savegre, Costa Rica. Methods: We counted total coliforms and Escherichia coli from monthly samples (2015-2018) at three sections of the largest aquacultural development in the upper drainage of the river. We collected samples at the fish ponds entrance, exit and 200 m downwards. Results: We found fewer total coliforms and E. coli in the water collected just at the exit of the fish ponds. We counted more total coliforms in 2016 and 2017, and more E. coli in 2016. Conclusions: Coliform and E. coli counts are high in the river, but, unexpectedly, low in the water discarded from the fish tanks. Perhaps the mucus produced by the trouts or substances released by mosses on the fish tank walls reduce bacterial growth, as suggested by other studies. River pollution appears to come from other sources.

Antimicrobial Resistance and Genetic Diversity of Campylobacter spp. Isolated from Broiler Chicken at Three Levels of the Poultry Production Chain in Costa Rica.

ABSTRACT: Campylobacter spp. are considered the most common bacterial cause of human gastroenteritis, one of the four main causes of diarrheal disease worldwide, and they are one of the main foodborne pathogens causing hospitalizations and deaths. Here, 148 strains of Campylobacter spp. isolated from poultry at farms, processing plants, and retail stores in Costa Rica were examined for resistance to six antibiotics. An agar dilution test was used to determine the MIC and susceptibility profiles against doxycycline, ciprofloxacin, nalidixic acid, enrofloxacin, chloramphenicol, and erythromycin. In addition, a pulsed-field gel electrophoresis analysis was carried out to determine the genotype relatedness of a representative subset of the isolates. Approximately 136 (92%) of the 148 analyzed isolates showed resistance to the tested drugs. Nalidixic acid, ciprofloxacin, and enrofloxacin were the antibiotics for which resistance occurred most frequently (91.2, 85.8, and 85.8%, respectively), followed by doxycycline (25.0%), chloramphenicol (5.4%), and erythromycin (2.7%). The profile conferring only resistance to quinolones was the most frequently found, and only 2.0% of the isolates showed resistance to quinolones and macrolides simultaneously. Results showed a high frequency of resistant Campylobacter spp. strains and evidenced the distribution, selection, and circulation of resistant strains along the poultry chain from farms to consumers. Cross-contamination and resistance seem to play important roles in the dissemination of these strains at specific points of the poultry chain, even when control measures are being taken. The establishment of effective surveillance and control strategies represents an essential tool for foodborne diseases mitigation. The rational use of antibiotics, especially those still showing efficacy, should be a priority in both human and veterinary medicine to contain the progress of this phenomenon and its consequences.

The ability of Aliarcobacter butzleri strains isolated from foods of animal origin in Costa Rica to form biofilm.

Aliarcobacter butzleri is a zoonotic emerging food and waterborne pathogen widely distributed in nature. It is present in food processing environments and can easily be spread through the food industry because of its ability to form biofilm. The aim of this work was to determine the ability of strains isolated in Costa Rica from different food matrixes of animal origin to form biofilm. Thirty-eight A. butzleri strains previously isolated and identified from animal origin products were analyzed using the method described by Stepmovic et al. (2000), in three culture broths, brain heart infusion broth, Boer broth and Houf broth. Results showed that 67% of poultry origin strains, 62.5% of meat origin strains and just 8% of milk origin strains showed ability to form biofilm. The findings of this study confirm the adherence ability of A. butzleri to form biofilm, a characteristic that can promote dispersion and cross contamination along food industry processing lines.

Presence of Listeria monocytogenes in Ready-to-Eat Meat Products Sold at Retail Stores in Costa Rica and Analysis of Contributing Factors.

ABSTRACT: Listeria monocytogenes is a pathogenic bacterium associated with ready-to-eat (RTE) meat products sold at the retail level. The objective of this research was to determine the prevalence of L. monocytogenes in RTE meat products sold at retail in Costa Rica and to study the factors associated with the levels of contamination; analyzed factors include hygienic practices within stores (cutting techniques and microbial contamination of products) and the behavior of the isolates (persistence against antimicrobials and transfer potential). A total of 190 samples of RTE meat products were collected and analyzed for the presence of coliforms and Listeria spp. Isolates of L. monocytogenes were then evaluated in terms of resistance to disinfectants (quaternary ammonium compound [QAC] and chlorine) and their transfer potential from food contact surfaces (knife and cutting boards). Overall Listeria spp. prevalence was 37.4% (71 of 190); Listeria innocua was present in 32.1% (61 of 190) of the products, and L. monocytogenes was found in just 2.6% (5 of 190) of the samples. Most contaminated samples were cut with a knife at the moment of purchase (44.2%). When analyzing practices within the stores, it was observed that L. monocytogenes transfer from inoculated knife to salchichón was higher for samples cut at the beginning of the experiment. In addition, L. monocytogenes transfer from inoculated cutting boards was independent of the number of slices but contamination from plastic was higher than wood. Regarding L. monocytogenes resistance to disinfectants, average reductions of 2.6 ± 1.1 log CFU/mL were detected after 6 min of exposure to 200 ppm of chlorine; however, chlorine resistance varied among the strains. Prevalence of L. monocytogenes in RTE meat products sold at retail could be associated with handling practices within the stores; further studies are necessary to estimate the impact of these practices on the overall risk for consumers.

Optimization of the In Vitro Bactericidal Effect of a Mixture of Chlorine and Sodium Gallate against Campylobacter spp. and Arcobacter butzleri.

ABSTRACT: Campylobacter spp. and Arcobacter butzleri are foodborne pathogens associated with the consumption of contaminated raw chicken meat. At the industry level, the combination of new and common antimicrobials could be used as a strategy to control the presence of pathogens in chicken carcasses. The objective of this study was to determine the bacteriostatic and bactericidal effects of a mixture of chlorine (Cl) and sodium gallate (SG) on a mixture of two Campylobacter species (Campylobacter jejuni and Campylobacter coli) and A. butzleri. Using a central composite experimental design, it was established that the optimum inhibitory SG-Cl concentration for Campylobacter spp. was 44 to 45 ppm. After 15 h of incubation, Campylobacter species growth was reduced by 37.5% and the effect of Cl was potentiated by SG at concentrations above 45 ppm. In the case of A. butzleri, optimum levels of 28 and 41 ppm were observed for SG and Cl, respectively; no synergism was reported, as this bacterium was more sensitive to lower Cl concentrations than Campylobacter. After a 20-min pretreatment with peracetic acid (50 ppm), the optimum condition to achieve a >1.0-Log CFU/mL reduction of Campylobacter spp. was exposure to 177 ppm of Cl and 44 ppm of SG for 56 min. As A. butzleri showed lower resistance to the bacteriostatic effect of the Cl-SG combination, it was assumed that optimum bactericidal conditions for Campylobacter spp. were effective to control the former; this was confirmed with subsequent validation of the model. The SG-Cl combination has bactericidal properties against Campylobacter and A. butzleri, and it may be a useful strategy to improve sanitary practices applied in the poultry industry.

Angiostrongylus costaricensis, un parásito neotropical cuyo diagnóstico y tratamiento siguen siendo controversiales

La angiostrongilosis abdominal es una parasitosis esporádica, que ocurre en países del neotrópico, especialmente en Costa Rica. Es una enfermedad cuyo diagnóstico es infrecuente y su tratamiento controversial. Se presenta un caso de un adulto que muestra un malestar generalizado, dolor abdominal y una intensa eosinofilia que lleva a la detección de una masa en la fosa iliaca inferior derecha. El diagnóstico definitivo se hace mediante la prueba de Morera y el tratamiento incluye el uso de azitromicina y metronidazol, no obstante no se usan antihelmínticos ni se realiza cirugía. El caso descrito pone de manifiesto que tanto el diagnóstico como el tratamiento de esta enfermedad parasitaria continúan siendo inciertos. No se descarta que exista un subregistro importante de esta parasitosis o que los síntomas sean confundidos con otras patologías.

Abdominal angiostrogyliasis is a sporadic parasitosis that occurs in Neotropical countries, mainly in Costa Rica. It is a disease with an infrequent diagnosis and a controversial treatment. We discuss a case of an adult that presents a severe generalized discomfort, abdominal pain and an intense eosinophilia that leads to the detection of a mass at the right lower quadrant. Definitive diagnosis is achieved by the Morera Test and the treatment includes the use of azythromicin and metronidazole: no antihelmintic drugs or surgery were used. The case shows that both the diagnosis and treatment of this parasitosis are uncertain. An important underreporting of the disease may occur, as well as confusion of the symptoms with other pathologies.

Antimicrobial activity of different sodium and potassium salts of carboxylic acid against some common foodborne pathogens and spoilage-associated bacteria / Actividad antimicrobiana de diferentes sales de ácidos carboxílicos de sodio y potasio contra algunos microorganismos patógenos y de deterioro asociados a alimentos

Cleaning and disinfection represent the most important activities associated with the elimination of dirt and microorganisms at food processing plants. Improper procedures may lead to cross contamination of food leading to its spoilage or even the transmission of foodborne pathogens. Several strategies have been used in order to achieve a good disinfection of sursalts; faces and products; nevertheless, microbial resistance to common-use-products has developed Potassium lately. Due to this fact, the development of new non-toxic-food compatible chemical agents that reduce the impact of foodborne pathogens and spoilage causing microorganisms is desirable for the food industry. The objective of the present study was to evaluate the antimicrobial activity of different sodium and potassium salts of aliphatic and aromatic carboxylic acid on the growth of common food spoilage and pathogenic microorganisms. Growth curves were determined for Leuconostoc mesenteroides, Lactobacillus plantarum, Enterococcus faecalis, Candida albicans, Pseudomonas aeruginosa, Salmonella Enteritidis, and Listeria monocytogenes in contact with different concentrations of carboxylic acid salts. The inhibitory effect of both aliphatic and aromatic carboxylic acid salts, in accordance with concentration levels, was 100 > 50 > 25 mg/ml. The inhibitory effect of aliphatic salts was butanoic > hexanoic> octanoic > decanoic and, benzoic > gallic > caffeic acid salts for aromatic salts. In general, sodium salts were more inhibitory than potassium salts (p < 0.05).

La limpieza y la desinfección representan las actividades más importantes asociadas a la eliminación de suciedad y microorganismos de las plantas procesadoras de alimentos. El uso de procedimientos incorrectos puede llevar a la contaminación cruzada de los alimentos y, por ende, al deterioro de estos o a la transmisión de patógenos de origen alimentario. Se han desarrollado varias estrategias con el fin de obtener una buena desinfección de superficies y productos; no obstante, ha aparecido resistencia microbiana frente a productos de uso común. Debido a esto, el desarrollo de agentes químicos no tóxicos capaces de reducir el impacto de patógenos de origen alimentario y microorganismos causantes de deterioro es deseable para la industria alimentaria. El objetivo de este estudio fue evaluar la actividad antimicrobiana de diferentes sales de sodio y potasio de ácidos carboxílicos alifáticos y aromáticos sobre algunos microorganismos patógenos y asociados a deterioro alimentario, analizando su impacto sobre el crecimiento. Se determinaron las curvas de crecimiento de Leuconostoc mesenteroides, Lactobacillus plantarum, Enterococcus faecalis, Candida albicans, Pseudomonas aeruginosa, Salmonella enteritidis y Listeria monocytogenes en presencia de diferentes concentraciones de las sales de ácidos carboxilicos. El efecto inhibitorio de las sales de ácidos carboxilicos alifáticos y aromáticos, según su nivel de concentración, se ordenó del siguiente modo: 100mg/ml > 50mg/ml > 25 mg/ml. El efecto de las sales de ácidos alifáticos siguió el orden butanoico > hexanoico > octanoico > decanoico, en tanto que las de ácidos aromáticos se ordenó del siguiente modo: benzoico > gálico >cafeico. En general, las sales de sodio fueron más inhibitorias que las de potasio (p < 0,05).

Antimicrobial activity of different sodium and potassium salts of carboxylic acid against some common foodborne pathogens and spoilage-associated bacteria.

Cleaning and disinfection represent the most important activities associated with the elimination of dirt and microorganisms at food processing plants. Improper procedures may lead to cross contamination of food leading to its spoilage or even the transmission of foodborne pathogens. Several strategies have been used in order to achieve a good disinfection of surfaces and products; nevertheless, microbial resistance to common-use-products has developed lately. Due to this fact, the development of new non-toxic-food compatible chemical agents that reduce the impact of foodborne pathogens and spoilage causing microorganisms is desirable for the food industry. The objective of the present study was to evaluate the antimicrobial activity of different sodium and potassium salts of aliphatic and aromatic carboxylic acid on the growth of common food spoilage and pathogenic microorganisms. Growth curves were determined for Leuconostoc mesenteroides, Lactobacillus plantarum, Enterococcus faecalis, Candida albicans, Pseudomonas aeruginosa, Salmonella Enteritidis, and Listeria monocytogenes in contact with different concentrations of carboxylic acid salts. The inhibitory effect of both aliphatic and aromatic carboxylic acid salts, in accordance with concentration levels, was 100>50>25mg/ml. The inhibitory effect of aliphatic salts was butanoic>hexanoic> octanoic>decanoic and, benzoic>gallic>caffeic acid salts for aromatic salts. In general, sodium salts were more inhibitory than potassium salts (p≤0.05).

Arcobacter Isolation from Minced Beef Samples in Costa Rica.

The presence of Arcobacter spp. in minced meat (including beef) samples has been well documented in different countries, with varying frequencies. Nevertheless, the only Latin American country reporting this bacterium in minced beef samples is Mexico, with a 28.8% frequency in 2003. Previous studies in Costa Rica have demonstrated the presence of Arcobacter species in samples taken from the poultry production chain, but still there are no studies performed in bovine meat. The aim of this study was to determine the frequency of this bacterium in 120 samples of minced beef acquired from the Central Valley region of Costa Rica and to describe the antibiotic sensitivity pattern of the isolates obtained. A total of 75 different Arcobacter strains were isolated from minced beef samples, for a final frequency of 48.3%. After species PCR identification, the strains were classified as A. butzleri (37.3%), A. cibarius (14.7%), A. thereius (12%), and Arcobacter spp. (36%). All samples were sensitive to gentamicin but were resistant to ampicillin, levofloxacin, nalidixic acid, and ciprofloxacin. The results obtained in this study show that the frequency of isolation of Arcobacter in minced beef samples is high and that there is a high resistance rate for antibiotics in common use. This suggests that Arcobacter represents a health risk for Costa Rica and that control measures should be developed to decrease its potential impact.

Formación de acrilamida durante el procesamiento de alimentos. Una revisión / Acrylamide formation during the processing of food. A review

ResumenEn abril del 2002, un grupo de investigadores suecos dio a conocer que algunos alimentos ricos en almidón y pobres en proteínas, sometidos a procesos con temperaturas mayores a 120°C (fritura, horneado, asado y tostado) contenían el pro-cancerígeno conocido como acrilamida. A partir de ese momento, se desató una verdadera carrera investigativa en torno al tema, generando más de 7000 publicaciones científicas relacionadas con el tema, solo en los últimos 4 años.Al día de hoy, las investigaciones realizadas dejan en claro que la formación de acrilamida en los alimentos involucra al aminoácido asparragina y a azúcares reductores, los cuales mediante la reacción de Maillard dan como resultado el mencionado compuesto, denominado actualmente como un contaminante del proceso o un contaminante neo formado.La investigación realizada, se puede decir tiene tres vertientes claramente definidas, una es explicar porque se da la presencia de acrilamida en los alimentos, otra se enfoca en el desarrollo de protocolos y tecnología de punta para la detección de la sustancia en diversos alimentos y la tercera tiene que ver con las medidas a tomar para mitigar la aparición de acrilamida en sustratos alimenticios. Esta revisión tiene como objetivo, brindar al lector una visión actualizada sobre estas tres vertientes anteriormente citadas.

AbstractIn April 2002, a Swedish group or researches informed that some food products with high starch and low protein constitution and submitted to temperature processes above 120°C contained a pro cancerigenous substance known as acrylamide. From this moment on, and until actual times, a research race around the theme has been established.Up to the date, research done clearly describes the formation of acrylamide in food from asparagine and reducing sugars, through Maillard's reaction, and is known as a process contaminant or a neo formed contaminant.Actual research on the theme has three different approaches, one that explains the presence of acrylamide in food, a second one that focusses in the development of protocols and technology for its detection in food and a third one that tries to develop mitigating measures for the appearance of acrylamide in food substrates. The aim of this review is to bring to the reader an actualized vision of these three approaches.

SURVIVAL CAPACITY OF Arcobacter butzleri INOCULATED IN POULTRY MEAT AT TWO DIFFERENT REFRIGERATION TEMPERATURES.

Arcobacter spp. are emerging enteropathogens and potential zoonotic agents that can be transmitted by food and water, being considered a public health risk. The high isolation rate of these bacteria from poultry products suggests that it may be a major source of human infections. One hallmark for differentiating the genus Arcobacter from Campylobacter includes their growing capacity at low temperatures (15-30 °C) under aerobic conditions. However, little is known about the population density variation of these bacteria at different refrigeration temperatures. The aim of this study was to determine the survival behavior of two different Arcobacter butzleri concentrations (10(4) CFU/mL and 10(7) CFU/mL) inoculated on chicken legs and held at two different refrigeration temperatures (4 and 10 °C) throughout storage time. Results have shown that A. butzleri had growing capacity both at 4 and 10 °C. No statistical difference between the survival trends was found for both bacterial concentrations and temperatures tested. This study shows that A. butzleri is a robust species with regard to storage temperature, and represents a potential health risk for poultry meat consumers.

Arcobacter: comparison of isolation methods, diversity, and potential pathogenic factors in commercially retailed chicken breast meat from Costa Rica.

Arcobacter species have been recognized as potential food- and waterborne pathogens. The lack of standardized isolation methods and the relatively scarce knowledge about their prevalence and distribution as emerging pathogens are due to the limitations in their detection and identification. This study aimed to determine the presence and the identification of Arcobacter in chicken breast samples commercially retailed in San José, Costa Rica, as well as to describe the adherence and invasive potential of the strains to human cells (HEp-2). Fifty chicken breast samples were collected from retail markets in the metropolitan area of the country. Six different isolation methodologies were applied for the isolation of Arcobacter. Isolation strategies consisted of combinations of enrichments in de Boer or Houf selective broths and subsequent isolation in blood agar (directly or with a previous passive membrane filtration step) or Arcobacter selective agar. Suspicious colonies were identified with a genus-specific PCR, whereas species-level identification was achieved with a multiplex PCR. The overall isolation frequency of Arcobacter was 56%. From the isolation strategies, the combination of enrichment in Houf selective broth followed by filtration on blood agar showed the best performance, with a sensitivity of 89% and a specificity of 84%. A total of 46 isolates were confirmed as Arcobacter with the genus-specific PCR, from which 27 (59%) corresponded to Arcobacter butzleri, 9 (19%) to Arcobacter cryaerophilus, and 10 (22%) were not identified with this multiplex PCR. Regarding the potential pathogenicity, 75% of the isolates presented adherence to HEp-2 cells, while only 22% were invasive to that cell line. All invasive strains were A. butzleri or nonidentified strains. The results show the presence of potentially pathogenic Arcobacter in poultry and recognize the importance it should receive as a potential foodborne pathogen from public health authorities.

[Microbiological stability through storage period of Sphyraena ensis in Costa Rica]. / Estudio de la estabilidad microbiológica de la barracuda a través del tiempo de almacenaje en Costa Rica.

At the present study some of the microbiological and biochemical changes that occur through storage period in Sphyraena ensis, a fish specie of frequent consumption in Costa Rica were studied. Samples of S. ensis obtained during rainy and dry season were evaluated. Analysis included aerobic psychrotrophic count, identification and count of Vibrio, Enterococcus and Pseudomonas through a six day storage period at two different refrigeration temperatures, 2 and 7 degrees C. Same time, a commercial enzymatic immunoassay was used for the evaluation of the variation on the concentration of histamine produced in the different samples. Results obtained show that there is an increase on the bacteriological counts through the storage period, this increase is bigger as refrigeration temperature increases. Most of the samples maintained at 7 degrees C showed counts above 106 CFU/g after three days of storage, those stored at 2 degrees C did not present such high population levels. Nevertheless, after 6 days of storage, all samples, despite the storage temperature used, presented levels above the described one. Also, an histamine concentration increased through storage time, especially when the product was conserved at the higher temperature due to an increase in the number of histidine descarboxilating bacteria. There is no statistical difference between the counts obtained during rainy or dry season; nevertheless, there is a difference assicieated to the bacterial genera isolated.

Capacidad de formación de biopelículas de cepas de Listeria monocytogenes aisladas a partir de queso tierno de origen costarricense / Biofilm formation capacity of Listeria monocytogens strains isolated from soft cheese from Costa Rica

Listeria monocytogenes, además de ser un género capaz de producir una enfermedad infecciosa grave en el hombre, puede formar biopelículas en distintas superficies relacionadas con el ambiente de producción alimentario. Éstas constituyen un serio problema debido a que son una fuente importante y constante de contaminación para los alimentos y el ambiente de producción, además de que las bacterias presentes en ellas poseen una aumentada resistencia hacia agentes físicos y químicos de uso frecuente. En el presente trabajo se estudió la capacidad de formación de biopelícula de cepas de L. monocytogenes previamente aisladas a partir de queso tierno bajo diferentes condiciones de temperatura y cultivo. Se utilizó una técnica de microplaca con diferentes medios de cultivo (CICC, CTS 1:20 y suero de queso) a diferentes temperaturas de incubación (refrigeración, ambiente y 35ºC). La capacidad de formación de biopelícula fue clasificada según la densidad óptica obtenida a 620 nm. Ninguna de las cepas evaluadas fue clasificada como formadora fuerte de biopelicula bajo ninguna de las variables estudiadas, sí se detectaron formadoras débiles y moderadas. Los resultados obtenidos ponen de manifiesto la influencia del contenido de nutrientes en el medio de cultivo sobre la formación de biopelícula, no obstante, el CICC fue el único medio que permitió la expresión de formadores moderados. Por el contrario, el suero de queso resultó poco favorecedor. La formación de biopelícula es un proceso multifactorial, donde el nivel de adsorción depende de gran cantidad de variables y cuyo estudio debe fomentarse, de manera que se desarrollen metodologías que permitan su reducción o eliminación, de manera que las industrias alimentarias aseguren productos inocuos y de buena calidad microbiológica.

Listeria monocytogenes is a bacteria associated with the production of severe infectious disease in human being, but also with the formation of biofilms in different surfaces related to the food production environment. Biofilm represents a serious problem in food industry, since it is a constant and important contamination source and also, bacteria present in it have an increased resistance towards physical and chemical agents of common use. The capacity of biofilm formation of L. monocytogenes strains previously isolated from soft cheese samples from Costa Rica was studied under different temperature and culture conditions. The microplate technique was performed using different culture media (BHIB, TSB 1:20 and cheese serum) and at different incubation temperatures (refrigeration, environmental and 35ºC). Biofilm formation capacity was classified according to the optical density obtained at 620nm. None of the strains evaluated was classified as strong biofilm former under any of the variables studied, nevertheless, weak and moderate formers were detected. The results obtained show the influence of the nutrient content of the culture media used over biofilm formation; BHIB was the only culture media that allowed the expression of moderate biofilm forms, contrary to cheese serum that did not promote biofilm production. Biofilm formation is a multifactorial process, where adsorption level depends on several variables and its study must be promoted in order to develop methodologies that allow its reduction or elimination, so food industries may offer safe food products to consumers.

[Biofilm formation capacity of Listeria monocytogens strains isolated from soft cheese from Costa Rica]. / Capacidad de formación de biopelículas de cepas de Listeria monocytogenes aisladas a partir de queso tierno de origen costarricense.

Listeria monocytogenes is a bacteria associated with the production of severe infectious disease in human being, but also with the formation of biofilms in different surfaces related to the food production environment. Biofilm represents a serious problem in food industry, since it is a constant and important contamination source and also, bacteria present in it have an increased resistance towards physical and chemical agents of common use. The capacity of biofilm formation of L. monocytogenes strains previously isolated from soft cheese samples from Costa Rica was studied under different temperature and culture conditions. The microplate technique was performed using different culture media (BHIB, TSB 1:20 and cheese serum) and at different incubation temperatures (refrigeration, environmental and 35 degrees C). Biofilm formation capacity was classified according to the optical density obtained at 620 nm. None of the strains evaluated was classified as strong biofilm former under any of the variables studied, nevertheless, weak and moderate formers were detected. The results obtained show the influence of the nutrient content of the culture media used over biofilm formation; BHIB was the only culture media that allowed the expression of moderate biofilm forms, contrary to cheese serum that did not promote biofilm production. Biofilm formation is a multifactorial process, where adsorption level depends on several variables and its study must be promoted in order to develop methodologies that allow its reduction or elimination, so food industries may offer safe food products to consumers.

[Evaluation of the potential adulteration of commercial honey distributed in Costa Rica compared with artesanian honey samples coming from specific apiaries]. / Evaluación de la posible adulteración de mieles de abeja comerciales de origen costarricense al compararlas con mieles artesanales provenientes de apiarios específicos.

Honey is the principal apiculture product, produced by Apis mellifera bee. This, as any other food product, has to accomplish certain quality standards, including physicochemical, organoleptic and microbiological properties. Within these parameters, different measures are considered as adulteration indicators, including hydroxymethylfurfural and diastase enzyme activity which are associated to overheating, and the sucrose, glucose and fructose content. In this study, a determination of previous parameters, additional to glucose, fructose and fructose/glucose index was performed to 35 artisan samples, obtained directly from beekeeper, previously characterized as having good productive practices and 25 commercial samples. Same time, the results obtained were compared and interpreted, in order to determine the kind of adulteration present in the honey sample. The 89% of artesian samples accomplished the parameters established by the Codex Alimentarius for HMF content, diastase activity, sucrose and simple sugars content. Nevertheless, only 20% (5) of the commercial samples accomplished the international and national normative. 24% of these samples presented succrose addition, 32% overheating or inverted sugar syrup addition, and 24% were adulterated with inverted sugar syrup.

Inmunoglobulina G Anti Helicobacter Pylori por ELISA y Western-blot en pacientes del Servicio de Gastroenterología del Hospital San vicente de Paul, Heredia / Immunoglobulin G Anti Helicobacter Pylori by ELISA and Western-blot in patients of Gastroenterology Service of San Vicente de Paul Hospital, Heredia

Justificación y objetivo: en Costa Rica el cáncer gástrico es una de las malignidades más frecuentes y de la mayor mortalidad y otros estudios han encontrado asociación entre este y el Helicobacter pylori. Esta bacteria es capaz de producir sustancias que alteran la mucosa gástrica, antígenos que han sido reconocidos por medio del Western-blot. El propósito de este trabajo fue realizar, por primera vez en nuestro país, un estudio de anticuerpos IgG-anti H. pylori por medio de Western-blot y lograr identificar los tipos de antígenos contra los cuales se desarrolla la respuesta inmunológica. Para ello se utilizaron sueros y cepas de H. pylori aisladas de pacientes costarricenses. Asimismo, se compararon los resultados obtenidos del Western-blot con una prueba de ELISA, para determinar la sensibilidad y especificidad diagnóstica, utilizando como referencia el estudio histológico de biopsia gástrica. Métodos: Se obtuvieron muestras de biopsia gástrica y suero de 83 pacientes referidos al Servicio de Gastroscopía del Hospital San Vicente de Paúl, Heredia. A cada uno se le realizó estudio histológico de biopsia gástrica y de anticuerpos IgG-anti H. pylori, por los métodos de ELISA y Western-blot. Resultados y Conclusiones: Por Western-blot se observaron bandas de proteínas de diferentes pesos moleculares, con un predominio de antígenos de H. pylori de bajo peso molecular. El Western-blot y el ELISA presentaron sensibilidades dianósticas del 89 por ciento y el 88 por ciento y especificades diagnósticas del 73 por ciento y el 71 por ciento, respectivamente, comparados con el estudio histológico. Descriptores: H. pylori, IgG, ELISA, Western-blot, suero

Análisis bacteriologico de helados, queso y empanadas de venta ambulante / Bacteriological analysis of ice cream, cheeses, small meat and cheese pies bought at street sellings (peddlings)

Se analizó la presencia de coliformes totales, coliformes fecales, Escherichia coli, Staphylococcus aureus, Salmonella sp y Shigella sp en 150 muestras de comida vendida en la calle: 50 helados caseros, 50 quesos no pasteurizados, y 50 empanadas, todo comprado en sitios y fechas diferentes en San José, Costa Rica, durante el período de enero a julio de 1990. Se utilizó la técnica del Número Más Probable y los métodos cualitativos de aislamiento recomendados por "Bacteriological Analytical Manual", 1974. Los resultados muestran una alta prevalencia de coliformes totales, coliformes fecales, Escherichia coli y Staphylococcus aureaus en los helados caseros y los quesos no pasteurizados. En las empanadas no se aisló alguna de estas bacterias, probablemente debido al proceso término que llevan en su fabricación. No se aisló. Salmonella ni Shigella