Category Archives: antimicrobial resistance

Research – Natural Antimicrobial Agents Utilized in Food Preservation

MDPI

Since the initial transformation of food surpluses, improving food quality and safety are of principal importance to human health. Due to the mass production (eggs, poultry, meat, grains, and pulses) of huge quantities of food, as well as storage and transport, food technologists are faced with challenges of contamination, undesirable microbial growth, the production of toxins, or the deterioration of food (food spoilage). Different food preserving methods (drying, smoking, etc.) have been developed throughout human history to increase the storage time of perishable raw materials or improve diets. For a long time, chemical preservatives used in the prevention of food spoilage or foodborne diseases were considered convenient for consumer protection. Effective in small concentrations and maintaining the sensory properties of food, as well as exhibiting stability at different temperatures or pH values, made their application in the prevention of food spoilage highly applicable. Indeed, they reduce food losses, increase quality, extend shelf life, and enable the development of new formulations as well as food stabilization and standardization [1]. Although consumers still demand safe, fresh-like (minimally processed), nutritionally highly valuable, high-quality foods, attitudes towards chemical conservatives have changed in contemporary nutrition. The continuous intake of chemicals during our (increasingly long-lived) lifetime and the documented adverse activity have changed consumer perceptions and attitudes towards synthetic preservatives in food technology [2]. More natural food production or the application of natural compounds in maintaining food safety have become highly desirable for many consumers in developed countries. Bio-preservatives, naturally occurring compounds from plants, animals, or microorganisms, can be successfully used in extending the shelf life of food, the inhibition/elimination of spoilage and pathogenic microorganisms, and the enhancement of food’s functionality and quality. Natural antimicrobials can be used directly in product formulation, incorporated into packaging material, or surface-coated to prevent spoilage processes or pathogen growth [3].
The most important naturally occurring used compounds in the food industry are essential oils, enzymes, and edible coatings.
Essential oils are highly volatile compounds from herbs and spices such as basil, thyme, oregano, cinnamon, clove, and rosemary, and are used to reduce spoilage microorganisms, increase overall food quality, and to inhibit food-borne pathogens such as SalmonellaListeria monocytogenesEscherichia coliBacillus cereus, and Staphylococcus aureus [4]. Essential oils are effective in inhibiting fungal growth as well as mycotoxin synthesis, reducing fungal damage and health risks [5,6]. Although essential oils are mainly used in the food industry as flavorings, by increasing knowledge of their modes of action and interactions with food matrix components, they can be successfully used in reducing targeted microbes.
Enzymes from animal sources such as lyzozime, lactoferrin, and bacteriocins (natamycin, nisin, pediocin, and reuterin) from bacteria are used in small concentrations in a similar way to prolong shelf life and inhibit pathogen proliferation [7].
Edible coatings, thin layers of naturally occurring polymers, with or without the addition of essential oils or enzymes, used for food coating reduce moisture loss, reduce microbial contamination, and minimize the impact of packaging materials on the environment [8].
Many natural compounds are promising for replacing synthetic food additives while improving overall quality and safety. Through cooperation, food scientists and food technologists can help meet consumer needs for safe and nutritionally valuable food without the adverse effect of synthetic preservatives.
This Special Issue aims to publish quality articles on natural antimicrobials in food preservation, their activity towards pathogens and contaminants, and novel formulations or applications in the production of safe and healthy foods.

Author Contributions

Conceptualization, S.K.-T. and H.P.; writing—original draft preparation, H.P.; writing—review and editing, S.K.-T.; supervision, S.K.-T. All authors have read and agreed to the published version of the manuscript.

Research – 2020 NARMS Update: Integrated Report Summary

FDA

The National Antimicrobial Resistance Monitoring System (NARMS) is a U.S. public health monitoring system that tracks antimicrobial resistance (AMR) in foodborne and other intestinal bacteria using a One Health approach. As outlined in the NARMS Strategic Plan: 2021-2025, the overall purpose of NARMS is to:

  • Monitor trends in antimicrobial resistance among enteric bacteria from humans, retail meats, and animals at the time of slaughter;
  • Disseminate timely information on antimicrobial resistance in pathogenic and commensal microorganisms to stakeholders in the U.S. and abroad to promote interventions that reduce resistance among foodborne bacteria;
  • Conduct research to better understand the emergence, persistence, and spread of antimicrobial resistance;
  • Provide timely antimicrobial resistance data for outbreak investigations; and
  • Provide data that assist the FDA in making decisions related to the approval of safe and effective antimicrobial drugs for animals.

NARMS gathers surveillance data from human clinical samples, animal slaughter samples and retail meat samples. This approach to integrated surveillance provides information needed to assess the nature and magnitude of resistance in bacteria moving through the food supply and causing illnesses in humans. The NARMS interactive data dashboards found below allow the user to explore data in different ways.

To learn how to access NARMS data via NARMS Now: Integrated Data, please view this tutorial.

Note: Users who create their own estimates using these data should cite the National Antimicrobial Resistance Monitoring System (NARMS) as the source of the original data. The data in these tables and displays are not confidential. Additional information on sampling and testing methodologies can be found on the NARMS Resources webpage.

Research -Holistic Strategies to Control Salmonella Infantis: An Emerging Challenge in the European Broiler Sector

MDPI

Abstract

Salmonella spp. has been globally recognized as one of the leading causes of acute human bacterial gastroenteritis resulting from the consumption of animal-derived products. Salmonella Enteritidis, S. Typhimurium, and its monophasic variant are the main serovars responsible for human disease. However, a serovar known as S. Infantis has emerged as the fourth most prevalent serovar associated with human disease. A total of 95% of isolated S. Infantis serovars originate from broilers and their derived products. This serovar is strongly associated with an elevated antimicrobial (AMR) and multidrug resistance, a resistance to disinfectants, an increased tolerance to environmental mercury, a heightened virulence, and an enhanced ability to form biofilms and attach to host cells. Furthermore, this serovar harbors genes that confer resistance to colistin, a last-resort antibiotic in human medicine, and it has the potential to acquire additional transferable AMR against other critically important antimicrobials, posing a new and significant challenge to global public health. This review provides an overview of the current status of the S. Infantis serovar in the poultry sector, focusing on its key virulence factors, including its virulence genes, antimicrobial resistance, and biofilm formation. Additionally, novel holistic strategies for controlling S. Infantis along the entire food chain are presented in this review.

Research – Staphylococcus aureus in the Processing Environment of Cured Meat Products

MDPI

Abstract

The presence of Staphylococcus aureus in six dry-cured meat-processing facilities was investigated. S. aureus was detected in 3.8% of surfaces from five facilities. The occurrence was clearly higher during processing (4.8%) than after cleaning and disinfection (1.4%). Thirty-eight isolates were typified by PFGE and MLST. Eleven sequence types (STs) were defined by MLST. ST30 (32%) and ST12 (24%) were the most abundant. Enterotoxin genes were detected in 53% of isolates. The enterotoxin A gene (sea) was present in all ST30 isolates, seb in one ST1 isolate, and sec in two ST45 isolates. Sixteen isolates harbored the enterotoxin gene cluster (egc) with four variations in the sequence. The toxic shock syndrome toxin gene (tst) was detected in 82% of isolates. Regarding antimicrobial resistance, twelve strains were susceptible to all the antibiotics tested (31.6%). However, 15.8% were resistant to three or more antimicrobials and, therefore, multidrug-resistant. Our results showed that in general, efficient cleaning and disinfection procedures were applied. Nonetheless, the presence of S. aureus with virulence determinants and resistance to antimicrobials, particularly multidrug-resistant MRSA ST398 strains, might represent a potential health hazard for consumers.

Research – Evaluation of antimicrobial activity and mechanism of Mentha longifolia L. essential oil

Wiley Online

As the interest in “natural” and “safe” products grows, the use of natural products instead of synthetic preservatives to combat food spoilage and poisoning caused by microorganisms during processing and storage has become a prioritized option. The present research evaluated the antibacterial activity of the Mentha longifolia L. essential oil (MLEO) against several pathogenic bacteria, and the mechanism of action against methicillin-resistant Staphylococcus aureus (MRSA). Gas Chromatography Quadrupole Time-of-Flight Mass Spectrometry (GC-Q-TOF MS) analysis suggested that main components of MLEO were carvone (47.39%) and limonene (12.48%). The oil showed considerable antibacterial activity with MIC values of 0.394–1.576 mg/mL, and could be a promising bactericide. Non-targeted metabolomics analysis based on GC-Q-TOF MS identified 66 different metabolites, and Kyoto Encyclopedia of Genes and Genomes enrichment analysis of these metabolites revealed that MLEO achieves the effects by affecting amino acid metabolism in MRSA.

Research -Antimicrobial-Resistant Listeria monocytogenes in Ready-to-Eat Foods: Implications for Food Safety and Risk Assessment

MDPI

Abstract

Antimicrobial resistance is an existential threat to the health sector, with far-reaching consequences in managing microbial infections. In this study, one hundred and ninety-four Listeria monocytogenes isolates were profiled for susceptibility using disc diffusion techniques. Possible foodborne listeriosis risk associated with ready-to-eat (RTE) foods (RTEF) and the risk of empirical treatment (EMPT) of L. monocytogenes infections, using multiple antimicrobial resistance indices (MARI) and antimicrobial resistance indices (ARI), respectively, were investigated. Twelve European Committee on Antimicrobial Susceptibility Testing (EUCAST) prescribed/recommended antimicrobials (EPAS) for the treatment of listeriosis and ten non-prescribed antimicrobials (non-PAS)] were evaluated. Antimicrobial resistance > 50% against PAs including sulfamethoxazole (61.86%), trimethoprim (56.19%), amoxicillin (42.27%), penicillin (41.24%), and erythromycin (40.21%) was observed. Resistance > 50% against non-PAS, including oxytetracycline (60.89%), cefotetan (59.28%), ceftriaxone (53.09%), and streptomycin (40.21%) was also observed. About 55.67% and 65.46% of the isolates had MARI scores ranging from 0.25–0.92 and 0.30–0.70 for EPAs and non-PAs, respectively. There was a significant difference (p < 0.01) between the MARI scores of the isolates for EPAs and non-PAs (means of 0.27 ± 0.21 and 0.31 ± 0.14, respectively). MARI/ARI scores above the Krumperman permissible threshold (>0.2) suggested a high risk/level of antimicrobial-resistant L. monocytogenes. The MARI risks of the non-success of empirical treatment (EMPT) attributed to EPAs and non-PAs were generally high (55.67% and 65.463%, respectively) due to the antimicrobial resistance of the isolates. MARI-based estimated success and non-success of EMPT if EUCAST-prescribed antimicrobials were administered for the treatment of listeriosis were 44.329% and 55.67%, respectively. The EMPT if non-prescribed antimicrobials were administered for the treatment of listeriosis was 34.53% and 65.46%, respectively. This indicates a potentially high risk with PAs and non-PAs for the treatment of L. monocytogenes infection. Furthermore, ARI scores ≤ 0.2 for EPAs were observed in polony, potato chips, muffins, and assorted sandwiches, whereas ARI scores for non-PAs were >0.2 across all the RTE food types. The ARI-based estimate identified potential risks associated with some RTE foods, including fried fish, red Vienna sausage, Russian sausage, fruit salad, bread, meat pies, fried chicken, cupcakes, and vetkoek. This investigation identified a high risk of EMPT due to the presence of antimicrobial-resistant L. monocytogenes in RTE foods, which could result in severe health consequences.

Research – The Role of Biofilms in the Pathogenesis of Animal Bacterial Infections

MDPI

Abstract

Biofilms are bacterial aggregates embedded in a self-produced, protective matrix. The biofilm lifestyle offers resilience to external threats such as the immune system, antimicrobials, and other treatments. It is therefore not surprising that biofilms have been observed to be present in a number of bacterial infections. This review describes biofilm-associated bacterial infections in most body systems of husbandry animals, including fish, as well as in sport and companion animals. The biofilms have been observed in the auditory, cardiovascular, central nervous, digestive, integumentary, reproductive, respiratory, urinary, and visual system. A number of potential roles that biofilms can play in disease pathogenesis are also described. Biofilms can induce or regulate local inflammation. For some bacterial species, biofilms appear to facilitate intracellular invasion. Biofilms can also obstruct the healing process by acting as a physical barrier. The long-term protection of bacteria in biofilms can contribute to chronic subclinical infections, Furthermore, a biofilm already present may be used by other pathogens to avoid elimination by the immune system. This review shows the importance of acknowledging the role of biofilms in animal bacterial infections, as this influences both diagnostic procedures and treatment.

Research – Foodborne Pathogen Biofilms: Development, Detection, Control, and Antimicrobial Resistance

MDPI

Bacteria can grow either as planktonic cells or as communities within biofilms. The biofilm growth mode is the dominant lifestyle of most bacterial species and 40–80% of microorganisms are associated with biofilms [1]. Biofilm is a sessile community that is irreversibly attached to a substratum or interface or to other members of the community [2]. It is surrounded by extracellular polymeric substances (EPS) that include extracellular polysaccharides, extracellular DNA, lipids, proteins, and other elements [3]. Biofilm formation is a complex but well-regulated process that can be classified into five distinct stages [4]. In the first stage, planktonic bacteria attach to a surface. Salmonella species, Listeria monocytogenesCampylobacter jejuni, or Escherichia coli have specific structures on the surface of the bacteria, such as flagella, curli, fimbriae, and pili, which help the bacteria attach [5].
The second stage is the adhesion step, which includes an initial reversible adhesion resulting in loose adhesion and a subsequent irreversible adhesion resulting in more stable adhesion. The third stage is to secrete EPS and form microcolonies. This is followed by biofilm maturation, which produces large amounts of EPS to grow in size and build three-dimensional structures. The final stage is the stage in which the biofilm is dispersed, releasing the planktonic cells and initiating the formation of a new biofilm at another location.
Microbial cells living within biofilms are protected from various environmental stresses such as desiccation, osmotic changes, oxidative stress, metal toxicity, radiation, antibiotics, disinfectants, and the host immune system [6]. Biofilms are much less sensitive to antimicrobial agents than planktonic cells, and several mechanisms contribute to their resistance to antimicrobials [7]. The exopolysaccharide matrix prevents the entry of antimicrobial agents by reducing diffusion and acting as a primary barrier [8]. Most antimicrobial agents kill rapidly dividing cells more effectively, but slow growth of biofilms leads to resistance [9]. Changes in metabolic activity within biofilms, genetic changes of antimicrobial resistant determinants in target cells, extrusion of antimicrobial agents using efflux pumps, and the presence of persistent cells also contribute to antimicrobial resistance [10].

Research – Recent insights into green antimicrobial packaging towards food safety reinforcement: A review

Wiley Online

Abstract

Food packaging is widely used method of food preservation around the world. It is an element that enhances the quality and food product safety. The primary function of packaging is to protect food from contamination, undesirable chemical reactions and to provide physical protection. Food spoilage caused by food-borne pathogens and microbes is increasing tremendously posing an enormous threat. In the field of food packaging, new biodegradable and natural antimicrobial agents from plants and animals are gaining popularity. Recent foodborne outbreaks have prompted more creative and safe ways to initiate efficient packaging systems in food industries. However, as consumer demand for natural food ingredients has grown as a result of increasing safety and availability, natural substances are thought to be safer. Antimicrobial packaging that incorporates natural antimicrobials is thus a viable active packaging innovation. One possibility for increasing the safety and quality of foods while prolonging their shelf life is to employ natural antibacterial packaging. This article focuses on environmentally friendly bio-based polymers that can be utilized in food packaging to enhance mechanical strength, gas permeability, and water resistance, among other features. It also includes useful information about natural antimicrobial agents found in fruits and vegetables, as well as animal by-products, their properties, safety laws, and uses aimed at improving and increasing food quality and safety.

Research – Campylobacter jejuni and Campylobacter coli from Houseflies in Commercial Turkey Farms Are Frequently Resistant to Multiple Antimicrobials and Exhibit Pronounced Genotypic Diversity

MDPI

Abstract

Campylobacter is a leading foodborne pathogen, and poultry are a major vehicle for infection. Houseflies play important roles in colonization of broiler flocks with Campylobacter but comparable information for turkey farms is limited. Here, we investigated houseflies as potential vectors for Campylobacter in 28 commercial turkey flocks. We characterized species, genotypes, and the antimicrobial resistance (AMR) profiles of Campylobacter from turkey feces and houseflies in the same turkey house. Of the 28 flocks, 25 yielded Campylobacter from turkey droppings and houseflies, with an average of 6.25 and 3.11 Campylobacter log CFU/g feces and log CFU/fly, respectively. Three flocks were negative for Campylobacter both in turkey feces and in houseflies. Both C. coli and C. jejuni were detected in turkey feces and houseflies, with C. coli more likely to be recovered from houseflies than feces. Determination of Campylobacter species, genotypes, and AMR profiles revealed up to six different strains in houseflies from a single house, including multidrug-resistant strains. For the predominant strain types, presence in houseflies was predictive of presence in feces, and vice versa. These findings suggest that houseflies may serve as vehicles for dissemination of Campylobacter, including multidrug-resistant strains, within a turkey house, and potentially between different turkey houses and farms in the same region.