Jesus A Santos

University of Leon | UNILEON · Department of Hygiene and Food Technology

Citation: López-Díaz, T.M.; Alegría, Á.; Rodríguez-Calleja, J.M.; Combarros-Fuertes, P.; Fresno, J.M.; Santos, J.A.; Flórez, A.B.; Mayo, B. Blue Cheeses: Microbiology and Its Role in the Sensory Characteristics. Dairy 2023, 4, 410-422. https:// Abstract: Blue cheeses are those whose matrix is veined with a blue, blue-grey, or blue-green colour due...

Foods of animal origin are increasingly considered a source of extended spectrum β-lactamase (ESBL) producing bacteria which can disseminate throughout the food chain and become a health concern for humans. This work aimed to evaluate the occurrence of ESBL-producing Escherichia coli in 100 retail minced meat samples taken in markets in Pamplona, C...

The dissemination of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli continues to be an important health concern, with the food production chain as a suggested reservoir. A collection of 31 strains, including ESBL-producing E. coli strains isolated from foods of animal origin and from human patients and reference collection strains,...

This study was conducted to assess the survival of 2 wild Shiga toxin-producing Escherichia coli strains (one serotype O157:H7 and one non-O157:H7) in ewe milk stored at different conditions and to examine the fate of the O157 strain during the manufacture and ripening of a Spanish sheep hard variety of raw milk cheese (Zamorano). The strains were...

Given the importance of lactic acid bacteria (LAB) in dairy products, this study assessed the antimicrobial properties of lactobacilli against some toxigenic Penicillium spp and pathogenic bacteria commonly found in cheese. Lactobacilli previously isolated from an artisanal Brazilian cheese (n = 32) were identified to species level by amplification...

Citation: Pintor-Cora, A.; Álvaro-Llorente, L.; Otero, A.; Rodríguez-Calleja, J.M.; Santos, J.A. Abstract: Fresh vegetables are an essential part of a healthy diet, but microbial contamination of fruits and vegetables is a serious concern to human health, not only for the presence of foodborne pathogens but because they can be a vehicle for the tra...

Please cite this article as: J. Ramos-Pereira, J. Mareze, D. Fernández, et al., Antifungal activity of lactic acid bacteria isolated from milk against Penicillium commune, P. nordicum, and P. verrucosum, International Journal of Food Microbiology (2021), https://doi. Abstract Penicillium spp. is considered a major spoilage fungus of cheeses. The us...

The aim of this work was to assess the antifungal and antioxidant activity of essential oils and ethanolic extracts from distilled solid by-products from aromatic plants (Artemisia dracunculus, Hyssopus officinalis, Lavandula stoechas, Origanum vulgare and Satureja montana) against 14 fungi strains isolated from sheep cheese and identified at speci...

This study was carried out to assess the survival of Shiga toxin-producing E. coli (STEC) and atypical enteropathogenic Escherichia coli (aEPEC) during the traditional manufacturing and ripening of Spanish hard cheese from raw cow’s milk. Milk samples were spiked with up to 3.1–3.5 log cfu/mL of one strain of STEC (O140:H32 serotype) and one of aEP...

Dissemination of enterobacteria that produce extended spectrum β-lactamases (ESBL) throughout the food chain has become an important health concern. This work aimed to evaluate the occurrence of ESBL-producing bacteria in foods of animal origin and to investigate the similarities between food and human isolates. The presence of beta-lactam-resistan...

Resumen: Primer reporte de Escherichia coli Productora de Toxina Shiga no O157 que codifica el gen de la enterohemolisina en carne cruda en Colombia. STEC no O157 enterohemolisina positivo en carne cruda. Dentro de los patotipos de Escherichia coli, el grupo STEC puede producir en el ser humano desde diarrea hemorrágica hasta insuficiencia renal ag...

Twenty-seven samples of raw goat's milk were collected from four farms in the NorthWest of Spain with the aim of analysing counts of various mesophilic bacteria and of determining the physical and chemical composition during different seasons of the year. Overall mean values for mesophilic aerobic microorganisms (Standard Plate Counts, SPCs) were a...

Abstract Antimicrobial resistance (AMR) represents a major challenge for Public Health and the scientific community, and requires immediate and drastic solutions. Acquired resistance to certain antimicrobials is already widespread to such an extent that their efficacy in the treatment of certain life‐threatening infections is already compromised. T...

The authors wish to make the following changes to their paper [1]. Due to an undetected mistake in the references management, certain errors appeared in the reference list and a reference was duplicated in Table 1[...]

There is currently significant international interest in promoting and enhancing the consumption of insects. Due to the nutritional properties together with the low ecological and economic impact of production, insect farming and the use of its by-products is turning into a promising food industry which is gradually being developed in Europe, suppo...

Antimicrobial resistance (AMR) surveillance is a critical step within risk assessment schemes, as it is the basis for informing global strategies, monitoring the effectiveness of public health interventions, and detecting new trends and emerging threats linked to food. Surveillance of AMR is currently based on the isolation of indicator microorgani...

Iron availability plays an important role in the virulence of micro-organisms, which develops different systems for iron acquisition. The expression of genes involved in iron uptake systems is usually regulated by Fur, a transcriptional regulator. Plesiomonas shigelloides is a Gram-negative food- and water-borne enteropathogen. Even though the mech...

A study about the influence of commercial packaging on physicochemical and microbiological characteristics of Spanish cured meat products was performed. For this purpose, 100 samples of fermented sausages (FS) and pieces of cured meat (P) were analyzed. Results for mean pH values were 5.12 (FS) and between 5.79–5.83 (P). All mean values for aw were...

The aim of this study was to characterize a collection of 44 Shiga toxin-producing (STEC) and enteropathogenic Escherichia coli (EPEC) isolated from goat milk and goat farm environment. Of the 19 STEC isolates, five (26.3%) carried the stx1 gene, four (21.1%) the stx2 gene and 10 (52.6%) presented both stx genes. Six (31.6%) STEC strains were eae-p...

The aim of this study was the characterization of a collection of 8 methicillin-resistant Staphylococcus aureus (MRSA) isolates, obtained from samples of fresh cheese (Doble Crema) elaborated from raw cow milk in small dairies in Colombia. All the isolates harbored the mecA and Panton-Valentine leukocidin (PVL) genes, presented with SCCmec type IV,...

The purpose of the study was to evaluate the microbiological status (mesophilic aerobic microorganism counts) of 68 samples of bulk tank goat's milk and determine the risk associated with the foodborne pathogens Staphylococcus aureus, enteropathogenic and Shiga toxin–producing Escherichia coli, and Cronobacter sakazakii. Most samples (83.8%) compli...

Full text available at http://revistas.unicordoba.edu.co/revistamvz/mvz-201/v20n1a10.pdf

The genus Psychrobacter includes Gram-negative bacteria, which are psychrophilic to psychrotolerant, halotolerant, and resistant to ionizing radiation. It belongs to the family Moraxellaceae and currently includes 34 valid species, some of them being associated with food spoilage and involved in human and animal diseases. Except for certain marine...

The genus Plesiomonas consists of only one species (Plesiomonas shigelloides) of Gram-negative bacilli, which belongs to the family Enterobacteriaceae. It is a microorganism of aquatic origin, pathogenic both for humans and animals that is recognized as a cause of extraintestinal infections and increasingly as an agent of gastrointestinal illness....

The antimicrobial activity of two packaging films (polypropylene – PP- and polyethylene terephthalate – PET-) coated with different concentrations (0, 4, 6 and 8%) of essential oil from Origanum vulgare (OR) and Ethyl Lauroyl Arginate HCl (LAE) was tested against two Escherichia coli O157:H7 strains using in vitro systems and a raw milk sheep chees...

Abstract The species diversity of 192 isolates of a collection of Gram-positive catalase-negative cocci (GPCNC) from sheep bulk tank milk was investigated using 16S rDNA sequencing. A molecular approach enabled the identification of 23 species of GPCNC of sanitary and technological importance within the Enterococcus, Streptococcus, Lactococcus, Aer...

The genus Plesiomonas consists of only one species (P. shigelloides) of Gram-negative bacilli, currently included in the family Enterobacteriaceae. It is a microorganism considered of aquatic origin, pathogenic both for humans and animals that is recognized as a cause of extraintestinal infections and increasingly as an agent of gastrointestinal il...

To analyse the effect of bulk tank Staphylococcus aureus and Escherichia coli presence on total bacterial count (BTTBC) and somatic cell count (BTSCC), and to study the factors influencing their prevalence, a total of 752 bulk tank milk samples from 205 dairy sheep flocks belonging to Consortium for Ovine Promotion (CPO) were collected between Janu...

A collection of 81 isolates of enteropathogenic Escherichia coli (EPEC) was obtained from samples of bulk tank sheep milk (62 isolates), ovine feces (4 isolates), sheep farm environment (water, 4 isolates; air, 1 isolate), and human stool samples (9 isolates). The strains were considered atypical EPEC organisms, carrying the eae gene without harbor...

Este trabajó fue llevado a cabo para: (a) encontrar la fuente de contaminación por EPECa en leche de ovino y, (b) determinar si existe relación entre cepas de origen ovino y humano. Se tipificaron 81 cepas EPECa, 72 de origen ovino (62 procedentes de muestras de leche y 10 de muestras ambientales de explotaciones) y 9 obtenidas de pacientes del Hos...

Aim: To isolate and characterize strains of Mycoplasma agalactiae from bulk tank and silo ewes' milk. Methods and results: Thirteen mycoplasma isolates were obtained from samples of sheep milk taken from bulk tank and large silos and identified as Myc. agalactiae by PCR-DGGE. The isolates were typed by pulsed field gel electrophoresis (PFGE), SD...

To analyze the relationship among the counts of different organisms and total bacterial count (BTTBC) and somatic cell count (BTSCC) as determined in dairy laboratories in ovine bulk tank milk, 751 bulk tank milk samples from 205 dairy sheep flocks belonging to Consortium for Ovine Promotion (CPO) were collected between January and December 2011. F...

The prevalence of coagulase-positive staphylococci (CPS) was studied among 390 samples of ewe milk. Fifty-seven (14.85%) samples of tank milk and all samples (6) of silo milk gave a positive result on Baird-Parker agar base supplemented with rabbit plasma fibrinogen, whereas amplification of the coagulase (coa) gene was successful in 6 (1.56%) samp...

A collection of Aeromonas isolates obtained over a three-year period in the same geographic area (León, NW of Spain) was characterized by (GTG)₅-PCR fingerprinting, amplified fragment length polymorphism (AFLP) analysis and gyrB gene sequence analysis. The isolates originated from human diarrheal stools (29 isolates), potable water (13 isolates), r...

This study was designed to analyze the effects of the storage and preservation conditions on counts of mesophilic, thermoduric, psychotrophic, coliform, Escherichia coli, Streptococcus agalactiae, and Staphylococcus aureus organisms in silo ovine milk. A total of 910 analytical determinations were conducted from aliquots of 10 silo ovine milks. The...

Among 800 stool specimens from patients with diarrhea submitted by Primary Care Centers for routine analysis to the Hospital of León (NW Spain) Microbiology and Parasitology Service, 32 (4%) were tested positive for Aeromonas spp. Mixed infections with other enteric pathogens occurred in 12 patients. A. caviae was isolated from 23 clinical specimen...

Rabbit hind legs were packaged under different modified atmospheres (Vacuum packaging (VP), 100% CO2 and a commercial gas blend) to determine an applicable packaging method for improving quality and durability of rabbit meat. The best atmosphere for preserving microbiological quality and extending shelf-life was 100% CO2 (5 weeks) followed by VP (b...

Aeromonas-associated cases of gastroenteritis are generally considered waterborne. The purpose of this study was to evaluate the potential microbiological risk associated with the presence of these bacteria in public drinking water. Over a period of one year, 132 drinking-water samples were monitored in León (NW of Spain, 137,000 inhabitants) for m...

Galicia's coast (northwestern Spain) is a major producer of bivalve molluscs. Over an 18-month period, the presence of Salmonella, Aeromonas, Plesiomonas shigelloides, Vibrio parahaemolyticus, and Clostridium botulinum was determined by PCR methods in mussels (22 batches) and infaunal bivalves (31 batches of clams and cockles) before and after depu...

Hemolysis is a means of providing pathogenic bacteria with heme iron in vivo. In a previous work, iron-influenced hemolytic activity against sheep erythrocytes was detected in cell-free supernatants, but not in the cell fraction of two environmental Plesiomonas shigelloides strains incubated without shaking. Both strains have the hugA gene, which e...

Lamb chops inoculated with 2.23-2.83 log cfu/g of E. coli O157:H7 strain NCTC 12900 were packed in air (AP), vacuum (VP), and two modified atmospheres (MAP) consisting of 100% CO2 and a commercial mixture of 35% CO2/35% O2/30% N2. All samples (initial total counts <3.5 log cfu/g) were stored in a commercial cold storage facility set at 4 degrees C...

Twenty-six Staphylococcus aureus isolates were recovered from rabbit carcasses and cuts during a period of seven months. Samples from 51 different animals, flocks and farms were obtained from five establishments in four Spanish provinces. To determine their diversity and possible origin, isolates were typed by three molecular and three phenotypic m...

Even though worldwide production of rabbit meat is >1,000,000 tons, little information is available for rabbit meat microbiology. This study provides data on the prevalence of Salmonella, Escherichia coli O157:H7, Yersinia enterocolitica, Listeria spp., motile Aeromonas spp., and Staphylococcus aureus on rabbit meat. A total of 24 rabbit carcasses...

PCR primers were designed and used to amplify a 435-bp fragment from the Plesiomonas shigelloides hugA gene. The PCR assay combined with a non-selective enrichment step proved to be a reliable procedure for P. shigelloides detection in fish meat. The incidence of this bacterium was investigated in 52 lots of pre-packed saltwater fish portions (cong...

To survey the presence of indigenous and nonindigenous foodborne bacterial pathogens in displayed prepacked portions of fresh marine fish. A survey of 50 different samples of fresh marine fish (conger, swordfish, sole, grouper and whiting) was conducted over a period of 5 months. Trays of fillets and steaks were obtained at retail level and tested...

Even though worldwide production of rabbit meat is over 1,000,000ton, little information is available on rabbit meat microbiology. This paper reports on the microflora developing on chill-stored rabbit carcasses. Four different lots of 24h post-mortem rabbit carcasses dressed and kept at 0°C in a medium-size abattoir were collected and evaluated fo...

The relative incidence of Psychrobacter spp. in rabbit meat, the radioresistance of these bacteria, and the growth of nonirradiated and irradiated psychrobacter isolates, alone and in coculture, during chilled storage of inoculated sterile rabbit meat was investigated. Psychrobacter spp. accounted for 4.2% of the storage psychrotrophic flora of 30...

Se estudió la prevalencia de Salmonella spp. en muestras de pescado fresco expendido en la ciudad de Pamplona encontrando una incidencia del 12%. Al comparar los métodos de aislamiento, se observó que la técnica de aislamiento que mayor número de cepas recuperó, fue la tradicional. En cualquiera de los casos, el medio de cultivo que presentó una ma...

World rabbit meat production is estimated to be over 1 million tons, and Spain is the third largest producer. Although rabbit meat is marketed and consumed worldwide, information on microbiological quality is very scarce. Here, we report indicator organisms, spoilage flora, sensory quality, and some physicochemical traits of 24 h postmortem chilled...

Expression of hemolytic and proteolytic activities throughout the growth cycle was investigated with two enterotoxic aeromonad strains assigned to the species Aeromonas hydrophila and Aeromonas veronii biovar sobria. Although growth kinetic data were dependent on strain, temperature, and substrate, maximum populations attained were higher than 9 lo...

Characterization of nonmotile bacteria associated with freshwater fish spoilage and that phenotypically resembled Psychrobacter spp. A population of 44 nonmotile Gram-negative rods could not be assigned to the genus Psychrobacter on the basis of a definitive test (transformation assay). Conventional and commercial phenotypic systems did not help in...

Development of a PCR assay for detection of aeromonads carrying the hlyA and/or aerA genes in fish. The protocol involves an overnight selective enrichment step in tryptic soy broth yeast extract containing 10 microg ml(-1) of ampicillin followed by extraction of DNA and PCR amplification of two haemolysin genes that contribute to the virulence of...

Fifty-four packages (each one belonging to a different lot) of vacuum-packed cold-smoked salmon (30) and trout (24) produced by six Spanish smokehouses were obtained at retail level after 3 weeks storage at 2+/-1 degrees C. Sensorial, chemical, physicochemical and microbiological characteristics were examined. Overall, pH, a(w), salt content in wat...

Twelve lots of fresh unskinned fillets of rainbow trout (Oncorhynchus mykiss) and 10 lots of fresh sliced salmon (Salmo salar) prepacked in trays wrapped with an oxygen-permeable film were obtained immediately after packing from two supermarkets having in-plant facilities for packaging wet fish. During storage at 3 degrees C, Listeria innocua was d...

To evaluate the public health significance of representative strains of two Aeromonas spp., mainly from freshwater fish, on the basis of production of virulence-associated factors and presence of the haemolytic genes aerA and hlyA. Eleven strains of Aer. hydrophila, three strains of Aer. veronii biovar sobria (all from freshwater fish) and one stra...

Fresh trout fillets and salmon slices packed in trays were obtained from two multinational chain supermarkets and evaluated for freshness and bacteriological quality immediately after packaging and during storage at 3 degrees C. Initial aerobic counts at 30 and 25 degrees C were significantly (P < 0.05) lower in trout fillets (5.27 +/- 0.57 and 4.8...

The surface mycoflora of "chorizo de Cantimpalos", a Spanish variety of fermented meat sausage characterised by a natural white covering, has been investigated. Among 54 mould strains isolated, 38 belonged to Penicillium subgenus Penicillium. The major species found (18 isolates) was identified as Penicillium commune, and the other dominant species...

Numbers and species of motile Aeromonas were determined in freshly caught freshwater fish, in the surrounding environment, and also during iced chilled storage of fish specimens. Although no significant differences were observed in water samples, initial levels for skin, gill, and intestines were significantly lower in farmed rainbow trout (Oncorhy...

Three phenotypic identification systems were employed to identify 106 strains of gram-negative, nonmotile, aerobic bacteria obtained during iced storage of wild (Salmo trutta and Esox lucius) and farmed (Oncorhynchus mykiss) freshwater fish. Using diagnostic tables and computer-assisted identification, the isolates were Psychrobacter (64 strains),...

The aim of this study was to determine the presence of hemolytic and elastolytic enzymes in several strains of Plesiomonas shigelloides in relation to the availability of iron in culture media. Hemolytic activity and elastolytic activity were detected in strains of P. shigelloides and were enhanced when the strains were grown in an iron-depleted me...

The hemolytic activity and siderophore production of several strains of motile aeromonads were determined. The hemolytic activity of Aeromonas caviae and Aeromonas eucrenophila was enhanced after trypsinization of the samples. The enhancement of hemolysis was observed in strains that carried an aerolysin-like gene, detected by a PCR procedure. Side...

Basic compositional and microbiological characteristics of Castellano cheese, a Spanish ripened variety made from ewes' milk, were studied. Mean values of moisture, total solids, total protein, fat, ash, NaCl, lactic acid, lactose, pH and aw in 25 cheeses produced from pasteurised milk were: 29.89%, 70.11%, 36.49%, 53.5%, 7.5%, 3.87%, 0.889%, 0.014...

The organization of the clusters of genes encoding proteins of the botulinum neurotoxin (BoNT) progenitor complex was elucidated in a strain of Clostridium botulinum producing type B and F neurotoxins. With PCR and sequencing strategies, the type B BoNT-gene cluster was found to be composed of genes encoding BoNT/B, nontoxic nonhemagglutinin compon...