Category Archives: Enterobacteriaceae

Research – Determination of Listeria monocytogenes, competitive microflora, microbial hygiene indicators and physico-chemical parameters during the shelf-life of the typical Mediterranean style fermented sausage “Salsiccia Sarda”

Journal of Food Protection

The aim of the present study was the determination of Listeria monocytogenes , competitive microbiota, microbial hygiene indicators and physico-chemical parameters in the typical Mediterranean Style fermented sausages “Salsiccia Sarda” . A batch of “Salsiccia Sarda” (25 samples) naturally contaminated by L. monocytogenes and vacuum packaged after 24 days of ripening was included in the study. Fifteen samples stored at 8° C were analysed after 13, 90 and lastly at the end of shelf-life, after 180 days from vacuum packaging. Ten vacuum packaged samples were stored at 12°C in a domestic fridge simulating temperature abuse and were evaluated at the end of the shelf-life. Samples were subjected to physico-chemical analysis (pH and aw) and investigated for the presence and enumeration of L. monocytogenes . Competitive microbiota, Lactic Acid Bacteria (LAB) and Coagulase negative Staphylococci (CNS), and microbial hygiene indicators (Total mesophilic bacterial counts, Enterobacteriaceae, Enterococcuss spp. and Staphylococcus aureus ) were determined in all the samples. Although a decreasing trend in L. monocytogenes prevalence was observed through the shelf-life, the detection of the pathogen in fermented sausages confirms the ability of L. monocytogenes to overcome the hurdles of the manufacturing process. The results of the present study highlight the importance to carefully evaluate the “Salsiccia Sarda” production process by Food Business Operators (FBOs) in order to maintain unfavourable conditions for the growth of L. monocytogenes .

Research – Microbiology and Epidemiology of Escherichia albertii—An Emerging Elusive Foodborne Pathogen


Escherichia albertii, a close relative of E. coli, is an emerging zoonotic foodborne pathogen associated with watery diarrhea mainly in children and immunocompromised individuals. E. albertii was initially classified as eae-positive Hafnia alvei, however, as more genetic and biochemical information became available it was reassigned to its current novel taxonomy. Its infections are common under conditions of poor hygiene with confirmed transmission via contaminated water and food, mainly poultry-based products. This pathogen has been isolated from various domestic and wild animals, with most isolates being derived from birds, implying that birds among other wild animals might act as its reservoir. Due to the absence of standardized isolation and identification protocols, E. albertii can be misidentified as other Enterobacteriaceae. Exploiting phenotypes such as its inability to ferment rhamnose and xylose and PCR assays targeting E. albertii-specific genes such as the cytolethal distending toxin and the DNA-binding transcriptional activator of cysteine biosynthesis encoding genes can be used to accurately identify this pathogen. Several gaps exist in our knowledge of E. albertii and need to be bridged. A deeper understanding of E. albertii epidemiology and physiology is required to allow the development of effective measures to control its transmission and infections. Overall, current data suggest that E. albertii might play a more significant role in global infectious diarrhea cases than previously assumed and is often overlooked or misidentified. Therefore, simple, and efficient diagnostic tools that cover E. albertii biodiversity are required for effective isolation and identification of this elusive agent of diarrhea. View Full-Text

Research – Plant Extract and Essential Oil Application against Food-Borne Pathogens in Raw Pork Meat


Herbal and plant extracts are being applied for a wide range of foods against different types of food-borne pathogens. In the present study, ethanolic and aqueous extracts (2% w/v) from cranberry (Vaccinium macrocarpon) and pomegranate (Punica granatum L.) plants were applied alone or in combination with two essential oils (thyme and oregano in a concentration of 0.150 μg/g) in pork meatballs and their antimicrobial activity was estimated. The extracts exhibited promising results (aqueous and ethanolic extracts of pomegranate and cranberry in a food-compatible concentration of 2% w/v) were applied to raw pork meatball production and their antimicrobial activity was recorded versus Enterobacteriaceae, total mesophilic bacteria, yeasts/molds, Staphylococcus spp., Pseudomonas spp. and lactic acid bacteria (LAB). The outcome demonstrated that meatballs containing aqueous extracts of pomegranate were more resistant to spoilage compared to all the other samples since they were preserved for more days. The chemical profiles of plant extracts were determined through LC-QTOF/MS and the chemical composition of the essential oils applied was determined with the use of GC/MS in order to identify the substances involved in the observed antimicrobial activity. Phenolic acids (quinic acid, chlorogenic acid), monoterpenes (p-cymene, carvacrol, thymol, limonene), organic acids (citric acid) and phenols were the main constituents found in the plant extracts and essential oils applied. These extracts of plant origin could be used as natural preservatives in meat products, even in low concentrations. View Full-Text

Research – Report on the equivalence between the disinfection of tools in slaughterhouses and cutting rooms with hot water, at a temperature not lower than 82 °C, and various alternative disinfection systems.


The different tools and utensils used in slaughterhouses and cutting rooms may lead to cross contamination if unsuitable cleaning and disinfecting procedures are used. In this regard, Regulation (EC) No. 853/2004 laying down specific hygiene rules for food of animal origin establishes that slaughterhouses and cutting rooms for ungulates as well as poultry and lagomorphs must have facilities for disinfecting

The Scientific Committee of the Spanish Agency for Food Safety and Nutrition (AESAN) has assessed several studies carried out in order to establish whether disinfection with four alternative systems may be considered equivalent to that conducted with water supplied at a temperature not less than 82 ºC.
After reviewing the studies, the AESAN Scientific Committee concludes that a notable effort has been made to demonstrate the equivalence of these systems. It is observed in these studies that the use of these compounds leads to reductions in the microorganisms studied which, under the testing conditions, appear to be similar to those obtained with the official method.
However, these studies have methodological limitations (number of repetitions, sampling plan, the microorganisms studied and method of analysis) which prevent establishing this equivalence.
Accordingly, the Committee makes a series of recommendations for conducting these studies: using swabs instead of contact slides; including the analysis of foodborne pathogenic microorganisms of interest in slaughterhouses; including detailed information on the disinfecting products used as well as the method of analysis; harmonising sampling and analysis procedures; guaranteeing the representativeness of the samples taken (it is suggested to take 5 samples per slaughterhouse per day-taken from at least 4 different locations-, using 4 different slaughterhouses in the study, during 5 non-consecutive days, uniformly distributed over a period of 3 months; that is to say, a total of 100 samples); ensuring that all samples analysed are acceptable based on the established criteria for mesophilic aerobes (0-10 cfu/cm2), enterobacteria (0-1 cfu/cm2), as well as the absence/cm2 for the pathogens Listeria monocytogenes and Salmonella.
Likewise, it is also recommended to draw up a sector-based Guide that, based on the recommendations made in this report, provides a detailed description of the protocol to be followed in order to demonstrate equivalence between the disinfection of tools in slaughterhouses and cutting rooms with hot water supplied at a temperature not less than 82 ºC and disinfection with alternative methods.

Research – Hygiene indicators and Salmonella sp. on swine carcass surfaces from two slaughterhouses in northern Portugal.

Journal of Food Protection

The monitorization of carcass surfaces contamination along the slaughter lines enables the verification of the slaughter operations hygiene and the good manufacturing practices. Pork meat is a common source of human non-typhoidal salmonellosis, one of the most frequently reported foodborne illnesses worldwide. This study aimed to gather data on microbial loads in carcass surfaces in two slaughterhouses, before and after evisceration. Salmonella enterica search was made after evisceration, due to the frequent reference to pork as being a common carrier of this microorganism. The contamination of carcass surfaces was evaluated by delimitation of surface area with sterilized templates (100 cm2), and sampled by gauze swabs. Enumeration of total aerobic mesophilic microorganisms, Enterobacteriaceae, and Escherichia coli was performed. The detection of Salmonella was performed for carcass surfaces after evisceration, and from animal liver and floor drains (environmental). Significant differences (p < 0.05) were observed for mesophilic microorganisms, Enterobacteriaceae, and E. coli counts on the external surfaces, with higher counts after evisceration. The neck and abdominal area presented higher levels for mesophilic microorganisms, Enterobacteriaceae and E. coli, and a high prevalence of Salmonella. Salmonella was detected only in one of the studied slaughterhouses; 19 out of 259 analysed carcass samples were positive for Salmonella (7.3%). Salmonella was also detected in two livers and in two floor drains. A collection of 52 Salmonella isolates (44 from carcasses, 5 from livers, 3 from drains) was gathered. Three serovars of Salmonella were identified (Typhimurium 4,5:i- , Wernigerone and Derby), and 53.8% of isolates were multidrug-resistant. The results demonstrate the need for continuous improvement of slaughtering operations and good manufacturing practices, to ensure food safety of pork produced in Portugal.

RASFF Alert – Animal Feed – Enterobacteriaceae – Dog Chews


Enterobacteriaceae in dog chews from the Netherlands in Belgium

RASFF Alert – Animal Feed – Enterobacteriaceae


Enterobacteriaceae in dog chews from Poland in France and Belgium

Research – Characterization of Microbiological Quality of Whole and Gutted Baltic Herring


There is growing interest in Baltic herring (Clupea harengus membras) and other undervalued, small-sized fish species for human consumption. Gutting or filleting of small-sized fish is impractical; hence, the aim of this study was to explore the suitability of the whole (ungutted) herring for food use. The microbiological quality of commercially fished whole and gutted herring was analysed with culture-dependent methods combined with identification of bacterial isolates with MALDI-TOF Mass Spectrometry and culture-independent 16S rRNA gene amplicon sequencing. Whole and gutted herring had between 2.8 and 5.3 log10 CFU g−1 aerobic mesophilic and psychrotrophic bacteria and between 2.2 and 5.6 log10 CFU g−1 H₂S-producing bacteria. Enterobacteria counts remained low in all the analysed herring batches. The herring microbiota largely comprised the phyla Proteobacteria, Firmicutes, and Actinobacteria (71.7% to 95.0%). ShewanellaPseudomonas, and Aeromonas were the most frequently isolated genera among the viable population; however, with the culture-independent approach, Shewanella followed by Psychrobacter were the most abundant genera. In some samples, a high relative abundance of the phylum Epsilonbacteraeota, represented by the genus Arcobacter, was detected. This study reports the bacterial diversity present in Baltic herring and shows that the microbiological quality was acceptable in all the analysed fish batches. View Full-Text

Research – Comparing the effectiveness of Cinnamomum zeylanicum essential oil and two common household sanitizers to reduce lettuce microbiota and prevent Salmonella enterica recontamination

Wiley Online

Vegetable Bacteria Danger

The washing step is necessary to remove biological and physical hazards from minimally processed vegetables. Nevertheless, the risk of foodborne diseases could persist even after washing due to postsanitizing contamination, and little is known about the antimicrobial effect of residual sanitizers. This study was conducted to compare the effectiveness of sodium hypochlorite (SH), sodium bicarbonate, and Cinnamomum zeylanicum essential oil (CEO) as sanitizers on lettuce (8°C, 48 h). First, the effect of sanitizers in reducing total aerobic mesophilic and psychrotrophic bacteria, yeast and molds, lactic acid bacteria, and Enterobacteriaceae on lettuce was evaluated with some insights on lettuce quality attributes (pH, color, and sensory analysis). Then, the capability of the treatments in preventing postwashing Salmonella adhesion on lettuce surface was investigated. Commercial SH disinfectant (solution at 2%) and CEO (0.5%) reduced microbial contamination in lettuce, without affecting the overall acceptability after 48 h at 8°C. SH reduced postsanitizing Salmonella adhesion of about 2.7 Log colony forming unit (CFU)/g. The microbial reduction was confirmed by confocal laser scanning microscopy, which also evidenced Salmonella internalization within stomata. Interestingly, CEO as well reduced Salmonella adhesion but with lower efficacy (0.44–1.00 Log CFU/g reduction), while sodium bicarbonate (15 mg/ml) was not effective. In conclusion, SH and CEO seem to be effective sanitizing agents, capable of improving the microbiological profile of fresh produce. In addition, the residual sanitizers, that remain on lettuce after washing, play a role in reducing Salmonella adhesion.

RASFF Alert – Animal Feed – Enterobacteriaceae –


Too high count of Enterobacteriaceae (> 30000 CFU/g) in dog chew products from Belgium in France, Germany and the Netherlands