R Araujo

Publications of R Araujo

• Effect of environmental parameters on the inactivation of the waterborne pathogen Campylobacter in a Mediterranean river.

  Authors: S Rodríguez, R Araujo

  Journal of water and health. 03/2012; 10(1):100-7.

  Campylobacter is a major waterborne pathogen that can be found in rivers of the Mediterranean area. Characteristics of these rivers change throughout the seasons due to variations in environmentalCampylobacter is a major waterborne pathogen that can be found in rivers of the Mediterranean area. Characteristics of these rivers change throughout the seasons due to variations in environmental parameters. As these variations may affect water survival of Campylobacter, we analyzed it in the Llobregat River using three approaches whose complexity increase progressively: (i) river water microcosms in the laboratory subjected to varying temperatures; (ii) in situ experiments carried out in the river, in which bacteria were exposed to varying levels of environmental parameters; and (iii) monitoring of thermotolerant Campylobacter in the river over two years. Campylobacter was quantified using the most probable number (MPN) method. The results showed that an increase in water temperature accelerates Campylobacter inactivation, measured as the loss of culturability. In situ experiments revealed that inactivation rates were also affected by sunlight, but not by pH, oxygen concentration or water conductivity. These observations are supported by the seasonality detected in Llobregat River. Campylobacter inactivation was fastest in spring and summer, when temperature and solar radiation were at their highest. The results highlight the importance of considering the inactivation rates in natural conditions to improve the monitoring of this pathogen and thus evaluate properly the health risk associated to water.

• Occurrence of thermotolerant Campylobacter species in surface waters of a Mediterranean area and in its prevailing pollution sources.

  Authors: S Rodríguez, R Araujo

  Journal of applied microbiology. 09/2010; 109(3):1027-34.

  To determine the prevalence of Campylobacter in surface waters of a highly populated Mediterranean area. Surface water and wastewater samples were collected from an area in the north-east of SpainTo determine the prevalence of Campylobacter in surface waters of a highly populated Mediterranean area. Surface water and wastewater samples were collected from an area in the north-east of Spain during a 2-year study. All the samples were analysed using the MPN method and Multiplex PCR to quantify and identify Campylobacter. It was detected in 82% of the samples from the Llobregat River with a mean of 1·3 MPN 100 ml(-1). The lowest counts were obtained in summer. Campylobacter coli was the predominant species in this river. The bacteria were isolated from marsh water but not from seawater samples. The highest counts of campylobacters were found in poultry wastewater where Camp. jejuni was the predominant species, as in urban sewage. In pig slurry, Camp. coli was the only species detected. Campylobacter jejuni and Camp. coli are present and widely distributed in the surface water of the studied area. The two species co-exist, with Camp. coli being predominant. In river water, campylobacter counts presented a seasonal distribution. No relationship with faecal indicators was found. This study provides the first data on the occurrence and concentrations of thermotolerant campylobacter species in surface water in a Mediterranean area.

• Detection of Helicobacter pylori DNA in human faeces and water with different levels of faecal pollution in the north-east of Spain.

  Authors: N Queralt, R Bartolomé, R Araujo

  Journal of applied microbiology. 02/2005; 98(4):889-95.

  AIMS: To assess the role of water in the faecal transmission of Helicobacter pylori by detecting the DNA of this pathogen in human faecal samples and environmental water samples with a range ofAIMS: To assess the role of water in the faecal transmission of Helicobacter pylori by detecting the DNA of this pathogen in human faecal samples and environmental water samples with a range of faecal pollution from the north-east of Spain. METHODS AND RESULTS: Semi-nested PCR was used to detect H. pylori in stools and water, both matrices with a complex biota. DNA was detected using highly specific primers of an ureA gene fragment. In addition, antigens were used to detect the bacteria in stools. Helicobacter pylori was detected in 33% of 36 human faecal samples and in 66% of wastewater samples, and 11% of river samples, but in none of the spring waters samples. Faecal pollution of the aquatic environment was tested analysing the presence of microbial indicators. CONCLUSIONS: We report the presence of H. pylori DNA in stools and in aquatic environments with different levels of faecal pollution, from the north-east of Spain. In this study a higher number of positive results were obtained in the more faecally polluted waters. SIGNIFICANCE AND IMPACT OF THE STUDY: These data indicate that water may be a vector of H. pylori in its faecal-oral route.

• Conservation of phage reference materials and water samples containing bacteriophages of enteric bacteria.

  Authors: J Mendez, J Jofre, F Lucena, N Contreras, K Mooijman, R Araujo

  Journal of virological methods. 01/2003; 106(2):215-24.

  The survival was determined in different conservation conditions of: somatic coliphages, F-specific RNA bacteriophages and phages infecting Bacteroides fragilis proposed as model micro-organisms forThe survival was determined in different conservation conditions of: somatic coliphages, F-specific RNA bacteriophages and phages infecting Bacteroides fragilis proposed as model micro-organisms for water quality control. Titres of phages of all groups either in pure culture phage suspensions or in naturally occurring phage suspensions were stable at (-70+/-10) degrees C and at (-20+/-5) degrees C when protected with glycerol. Moreover, phage analysis of stored suspensions demonstrated that their numbers were homogeneous, both between vials and within vials, and consequently they can be used as reference materials. Furthermore, changes in the storage temperature of the vials cause unpredictable changes in the numbers of bacteriophages. Consequently, phage reference materials and samples containing a quantitative number of phages must be maintained and dispatched at a constant temperature. Consequently, the results indicate that bacteriophages should be packed in dry ice during transport and storage. Finally, the number of phages in water samples stored at (5+/-3) degrees C in the dark does not decrease significantly during the first 72 h of storage. In addition, phage concentrates from natural samples obtained by adsorption-elution to cellulose nitrate filters and mixed with 10% glycerol were stable at least for 2 months at (-70+/-10) degrees C and at (-20+/-5) degrees C.

• Optimisation and standardisation of a method for detecting and enumerating bacteriophages infecting Bacteroides fragilis.

  Authors: R Araujo, M Muniesa, J Méndez, A Puig, N Queralt, F Lucena, J Jofre

  Journal of virological methods. 05/2001; 93(1-2):127-36.

  A method for the detection and enumeration of bacteriophages infecting Bacteroides fragilis has been standardised. The recommended host strain is RYC2056 (ATCC 700786) because of the relatively highA method for the detection and enumeration of bacteriophages infecting Bacteroides fragilis has been standardised. The recommended host strain is RYC2056 (ATCC 700786) because of the relatively high counts (10(4)-10(5) PFU/100ml) that it recovers in sewage from very different geographical areas. The addition of 0.25% bile to the culture and assay media and the manipulation of the host strain under strict anaerobic conditions resulted in a significant increase (more than 100%) in the number of phages detected. No other changes in the media and culture conditions resulted in changes in the phage counts detected. However, these increases do not justify changing the culture conditions and media described, taking into consideration that bile renders the media cloudy making it difficult to follow the host growth and that most laboratories do not have the facilities to work under strict anaerobic conditions. Nalidixic acid (100 microg/ml) and kanamycin (100 microg/ml) in the assay medium significantly reduce the background flora from polluted samples without affecting the phage counts. Freezing cultures just before the end of the log-phage growth at (-70+/-10) degrees C with BSA-sucrose as cryoprotector, storing of 1-2 ml in glass vials at (-70+/-10) degrees C and using them directly to inoculate fresh broth allows the obtention of cultures ready for phage enumeration in about 2.5 h. All these developments have been incorporated into a procedure that makes the method for detecting phages infecting B. fragilis as workable as the standardised methods available for the detection of coliphages.

• Identification of cell wall proteins of Bacteroides fragilis to which bacteriophage B40-8 binds specifically.

  Authors: A Puig, R Araujo, J Jofre, J Frias-Lopez

  Microbiology (Reading, England). 03/2001; 147(Pt 2):281-8.

  Bacteriophage infecting Bacteroides fragilis, one of the most abundant bacteria in the human colon, have been proposed as indicators of virological faecal pollution. The first identification of aBacteriophage infecting Bacteroides fragilis, one of the most abundant bacteria in the human colon, have been proposed as indicators of virological faecal pollution. The first identification of a receptor for a bacteriophage in B. fragilis is reported here. First, resistant mutants were characterized following phage inactivation, and it was shown that cell wall proteins are involved in phage binding. Then the proteins involved were identified by various approaches: (i) comparison of the protein profiles of wild-type B. fragilis HSP40 and phage-resistant mutants; (ii) application of a modification of the virus overlay protein blot assay (VOPBA). At least two proteins of B. fragilis, with apparent molecular masses of 35 +/- 5 kDa and 65 +/- 5 kDa, bind to B40-8. This result was later confirmed by running a complex consisting of this phage bound to radiolabelled proteins of B. fragilis on an immunoaffinity column loaded with a specific antibody against the phage. Cell proteins retained in the column also coincided with the proteins that differed in the profiles of resistant mutants. Finally, to identify the potential function of these two proteins, their N-terminal sequences were determined and compared to published sequences, but no homologies were found.

• Diversity of bacteroides fragilis strains in their capacity to recover phages from human and animal wastes and from fecally polluted wastewater.

  Authors: A Puig, N Queralt, J Jofre, R Araujo

  Applied and environmental microbiology. 05/1999; 65(4):1772-6.

  Great differences in capability to detect bacteriophages from urban sewage of the area of Barcelona existed among 115 strains of Bacteroides fragilis. The capability of six of the strains to detectGreat differences in capability to detect bacteriophages from urban sewage of the area of Barcelona existed among 115 strains of Bacteroides fragilis. The capability of six of the strains to detect phages in a variety of feces and wastewater was studied. Strains HSP40 and RYC4023 detected similar numbers of phages in urban sewage and did not detect phages in animal feces. The other four strains detected phages in the feces of different animal species and in wastewater of both human and animal origin. Strain RYC2056 recovered consistently higher counts than the other strains and also detected counts ranging from 10(1) to approximately 10(3) phages per ml in urban sewage from different geographical areas. This strain detected bacteriophages in animal feces even though their relative concentration with respect to the other fecal indicators was significantly lower in wastewater polluted with animal feces than in urban sewage.

• Bacteriophages of enteric bacteria in drinking water, comparison of their distribution in two countries.

  Authors: R Armon, R Araujo, Y Kott, F Lucena, J Jofre

  Journal of applied microbiology. 12/1997; 83(5):627-33.

  The presence of bacteriophages infecting enteric bacteria was tested in more than 1500 drinking water samples in Israel and Spain. Bacteriophages tested were somatic coliphages, F-specificThe presence of bacteriophages infecting enteric bacteria was tested in more than 1500 drinking water samples in Israel and Spain. Bacteriophages tested were somatic coliphages, F-specific bacteriophages and Bacteroides fragilis bacteriophages. The three groups of bacteriophage were isolated in 100 ml water samples by the presence/absence test with similar frequencies, which ranged from 4.4% for somatic coliphages to 6.1% for bacteriophages infecting Bact. fragilis. In contrast, the frequency of isolation of bacteriophages was significantly higher than the frequency of isolation of faecal coliforms, which averaged only 1.9%. No significant differences were observed between the frequencies of isolation between the samples tested in Spain and those tested in Israel. The percentage of groundwater samples containing faecal coliforms and somatic coliphages was reduced significantly by chlorination, despite known deficiencies. However, there was no effect on the occurrence of F-specific bacteriophages and Bact. fragilis bacteriophages.

• Simple concentration method for bacteriophages of Bacteroides fragilis in drinking water.

  Authors: F Lucena, M Muniesa, A Puig, R Araujo, J Jofre

  Journal of virological methods. 09/1995; 54(2-3):121-30.

  A membrane of inorganic material with a honeycomb pore structure was used to concentrate phages infecting Bacteroides fragilis from drinking water. Phages were removed from the membrane with 0.25 MA membrane of inorganic material with a honeycomb pore structure was used to concentrate phages infecting Bacteroides fragilis from drinking water. Phages were removed from the membrane with 0.25 M glycine buffer pH 9.5. Phages were not inactivated by storage in this buffer neutralized to pH 7.0 for at least 9 days at 4 degrees C. The method allows recovery of around 50% in drinking water. When the turbidity of the water increased, the efficiency of the concentration decreased markedly. The efficiency of concentration was evaluated versus a presence/absence test in 317 water samples with turbidity level below the threshold of drinking water. Results obtained by concentration of 11 provided data which were significantly more informative than the presence/absence tests carried out on 100 ml. A number of additional tests carried out with both somatic and F-specific coliphages indicated that these conclusions can be extended to these groups of bacteriophages.

• Culture and decontamination methods affecting enumeration of phages infecting Bacteroides fragilis in sewage.

  Authors: C Tartera, R Araujo, T Michel, J Jofre

  Applied and environmental microbiology. 09/1992; 58(8):2670-3.

  A new medium has been adapted for the growth of Bacteroides fragilis so that its phages can be recovered from environmental samples, and its efficiency has been assessed. Polyvinylidene difluorideA new medium has been adapted for the growth of Bacteroides fragilis so that its phages can be recovered from environmental samples, and its efficiency has been assessed. Polyvinylidene difluoride membranes allow significantly higher recoveries among different membrane filters used to decontaminate the samples. In all cases, a number of phages remain in the filters and a percentage of them can be recovered by treatment with an eluant.

• Comparison of different media for the identification and quantification of Aeromonas spp. in water.

  Authors: F Ribas, R Araujo, J Frias, J M Huguet, F R Ribas, F Lucena

  Antonie van Leeuwenhoek. 05/1991; 59(4):225-8.

  In order to assess the suitability of the Starch glutamate ampicillin penicillin-10C agar for the isolation of Aeromonas spp. from waters it was necessary to compare the properties of this mediumIn order to assess the suitability of the Starch glutamate ampicillin penicillin-10C agar for the isolation of Aeromonas spp. from waters it was necessary to compare the properties of this medium with those of three others, Starch ampicillin agar, Ampicillin dextrin agar and m-Aeromonas medium, and to monitor different kinds of waters. A selection of forty eight samples were taken from moderately polluted river water, highly polluted river water, polluted sea water (littoral) and treatment & distribution water and monitored using these media. The results were similar with Ampicillin dextrin agar, m-Aeromonas medium and Starch glutamate ampicillin penicillin-10C, but the simplicity of composition and use and its selectivity recommends the last medium as the most adequate for the isolation of Aeromonas spp.

• Usefulness of bacteriophages infecting Bacteroides fragilis as index microorganisms of remote faecal pollution

  Authors: F. Lucena, R. Araujo, J. Jofre

  Water Research.

  Levels of faecal bacteria, somatic coliphages and bacteriophages of Bacteroides fragilis were counted in marine sediments and groundwater as representatives of environments with remote faecalLevels of faecal bacteria, somatic coliphages and bacteriophages of Bacteroides fragilis were counted in marine sediments and groundwater as representatives of environments with remote faecal pollution. Additionally, enterovirus were measured in the marine sediments. Clear changes of the proportions of the different microorganisms are observed when microbial numbers in groundwater and marine sediments are compared to the numbers found in sewage or water recently polluted by sewage. These changes show that phages of B. fragilis reach sites that receive persistent pollution more successfully than somatic coliphages or indicator bacteria, with the exception of Clostridium perfringens. Multifactorial analysis of marine sediments and groundwater data clustered phages, viruses and C. perfringens in one factor and faecal bacteria in another. These data clearly suggest that Clostridium, phages of B. fragilis and, in some cases enteroviruses, are better index microorganisms of remote faecal pollution than present bacterial indicators.