Category Archives: Microbiology

Research – Biofilm Formation by Pathogenic Bacteria: Applying a Staphylococcus aureus Model to Appraise Potential Targets for Therapeutic Intervention

MDPI

Staphylococcus

Carried in the nasal passages by up to 30% of humans, Staphylococcus aureus is recognized to be a successful opportunistic pathogen. It is a frequent cause of infections of the upper respiratory tract, including sinusitis, and of the skin, typically abscesses, as well as of food poisoning and medical device contamination. The antimicrobial resistance of such, often chronic, health conditions is underpinned by the unique structure of bacterial biofilm, which is the focus of increasing research to try to overcome this serious public health challenge. Due to the protective barrier of an exopolysaccharide matrix, bacteria that are embedded within biofilm are highly resistant both to an infected individual’s immune response and to any treating antibiotics. An in-depth appraisal of the stepwise progression of biofilm formation by S. aureus, used as a model infection for all cases of bacterial antibiotic resistance, has enhanced understanding of this complicated microscopic structure and served to highlight possible intervention targets for both patient cure and community infection control. While antibiotic therapy offers a practical means of treatment and prevention, the most favorable results are achieved in combination with other methods. This review provides an overview of S. aureus biofilm development, outlines the current range of anti-biofilm agents that are used against each stage and summarizes their relative merits. View Full-Text

Research – Safety and Quality of Canned Sardines after Opening: A Shelf-Stability Study

MDPI

This study aimed to define the shelf life of canned sardines after opening to increase consumer awareness of their quality and safety and reduce food waste. For this purpose, canned sardines (Sardina pilchardus) packed with different sauces were opened and stored at 4 °C for 7 days. Microbiological, sensorial, physical and chemical stability was monitored daily by standard methodologies. Results show that the overall quality and safety are highly dependent on the sauce type. To preserve their full quality, sardines in brine and in vegetable oil should be consumed up to 1 day after opening, while sardines in tomato sauce were stable for up to 3 days, although none were considered nonedible up to the 7th day. Many parameters demonstrated statistical differences and correlations with storage, although they were not as decisive as sensory evaluation. This integrated approach should be adopted by the food industry and regulating authorities to provide information to consumers regarding the quality and safety of handled goods. View Full-Text

Research – Food Poisoning While Breastfeeding – What you need to know.

Food Poisoning News

Food poisoning can be a scary prospect, especially for breastfeeding mothers. But with a little knowledge, you can keep yourself and your baby safe. It is a common illness that can affect anyone. If you are breastfeeding and experience food poisoning, it is important to know what to do to protect your baby.

You can continue breastfeeding if you have food poisoning. In fact, the Centers for Disease Control and Prevention (CDC) even recommends that you continue breastfeeding if you have food poisoning.

The reason is that most germs that cause food poisoning are not passed from mother to baby through breast milk. If you are feeling ill, be sure to drink plenty of fluids (rehydration solutions like Pedialyte are best) so that you don’t get dehydrated. Dehydration can make you feel worse and can make it harder for your body to fight off any infection.

USA – How to Report Seafood-Related Toxin and Scombrotoxin Fish Poisoning Illnesses

FDA

To help FDA effectively investigate, remove unsafe seafood products from the market, and develop new prevention strategies, the FDA relies on illness reporting from public health officials and healthcare providers. While most foodborne outbreaks are tracked through the FDA’s Coordinated Outbreak Response and Evaluation (CORE) network, seafood-related illnesses caused by natural toxins have a unique reporting mechanism. This web page provides information on commonly occurring seafood-related illnesses and how to report them to the FDA.  To report an illness from raw bivalve molluscan shellfish, email the FDA at shellfishepi@fda.hhs.gov.

The FDA receives reports of illnesses associated with the consumption of specific types of fish. These illnesses may originate from the activity of certain bacteria, toxins produced by marine algae, or hazards inherent in the fish.

Commonly occurring illness:

Illness and reporting information for the commonly occurring illnesses are provided in each section. Contact the FDA with any questions or need for clarification of the illness or reporting.

In addition to the illnesses listed above, reporting of other less frequently occurring illnesses from natural toxins may be accomplished by emailing the FDA at Seafood.Illness@fda.hhs.gov.  Refer to Chapter 6 of the “Fish and Fishery Products Hazards and Controls Guidance” for a comprehensive list of natural toxin illnesses. To report illnesses related to miscellaneous natural toxin illnesses, please email FDA at Seafood.Illness@fda.hhs.gov.

The FDA works with first responders, physicians, and state and local health departments to investigate illnesses and outbreaks, manage them, and learn how to lessen future occurrences.

Research – A Multi-Skilled Mathematical Model of Bacterial Attachment in Initiation of Biofilms

MDPI

Biofilm of antibiotic resistant bacteria

The initial step of biofilm formation is bacteria attachment to biotic or abiotic surfaces and other bacteria through intra or interspecies interactions. Adhesion can be influenced by physicochemical conditions of the environment, such as iron. There is no available mathematical model of bacterial attachment giving realistic initiation rather than random adhesion. We describe a simple stochastic attachment model, from the simplest case in two dimensions with one bacterial species attaching on a homogeneous flat surface to more complex situations, with either several bacterial species, inhomogeneous or non-flat surfaces, or in three dimensions. The model depends on attachment probabilities (on the surface, laterally, or vertically on bacteria). Effects of each of these parameters were analyzed. This mathematical model is then applied to experimental oral microcolonies of Porphyromonas gingivalisStreptococcus gordonii, and Treponema denticola, either as mono-, two, or three species, under different iron concentrations. The model allows to characterize the adhesion of three bacterial species and explore the effect of iron on attachment. This model appears as a powerful tool for initial attachment analysis of bacterial species. It will enable further modeling of biofilm formation in later steps with biofilm initialization more relevant to real-life subgingival biofilms. View Full-Text

Research – Molecular Characterization of Staphylococcus aureus Strains Isolated from Mobile Phones

MDPI

Staph

The widespread use of mobile phones (MP) among healthcare personnel might be considered as an important source of contamination. One of the most pathogenic bacteria to humans is Staphylococcus aureus, which can be transmitted through the constant use of MP. Nevertheless, which specific type of strains are transmitted and which are their sources have not been sufficiently studied. The aim of this study is to determine the source of contamination of MP and characterize the corresponding genotypic and phenotypic properties of the strains found. Nose, pharynx, and MP samples were taken from a group of health science students. We were able to determinate the clonality of the isolated strains by pulsed-field gel electrophoresis (PFGE) and spa gene typing (spa-type). Adhesin and toxin genes were detected, and the capacity of biofilm formation was determined. Several of the MP exhibited strains of S. aureus present in the nose and/or pharynx of their owners. methicillin-susceptible Staphylococcus aureus (MSSA), hospital-acquired methicillin-resistant S. aureus (HA-MRSA), and community-acquired methicillin-resistant S. aureus (CA-MRSA) strains were found, which indicated a variety of genotypes. This study concludes that MP can be contaminated with the strains of S. aureus present in the nose and/or pharynx of the owners; these strains can be of different types and there is no dominant genotype. View Full-Text

Research – Comprehensive Review of Fungi on Coffee

MDPI

Coffee is grown in more than 80 countries as a cash crop and consumed worldwide as a beverage and food additive. It is susceptible to fungal infection during growth, processing and storage. Fungal infections, in particular, can seriously affect the quality of coffee and threaten human health. The data for this comprehensive review were collected from the United States Department of Agriculture, Agricultural Research Service (USDA ARS) website and published papers. This review lists the fungal species reported on coffee based on taxonomy, life mode, host, affected plant part and region. Five major fungal diseases and mycotoxin-producing species (post-harvest diseases of coffee) are also discussed. Furthermore, we address why coffee yield and quality are affected by fungi and propose methods to control fungal infections to increase coffee yield and improve quality. Endophytic fungi and their potential as biological control agents of coffee disease are also discussed.

Research – Selection of Microbial Targets for Treatments to Preserve Fresh Carrot Juice

MDPI

Fresh carrot juice presents nutritional and organoleptic qualities which have to be preserved. However, it is a fast perishable beverage, and its low-acidic pH promotes the development of foodborne pathogens and spoilage microorganisms. This study aims to assess the modification and variability of physicochemical and microbial indicators during storage of carrot juice, and to isolate and select microorganisms to be used as promoters of spoilage to quantify the effect of preservation treatments. To achieve that, 10 batches of carrot Daucus carota cv. Maestro juice were prepared independently, stored up to 14 days at 4 °C and analyzed. Volatile compound composition differed mainly according to the analyzed batch. During storage, an increase of the content of ethanol, ethyl acetate or 2-methoxyphenol, which are produced by different microorganisms, was noticed. Isolation of bacteria revealed Pseudomonas, lactic acid bacteria, and enterobacteria, some of them provoking odor modification of carrot juice at 4 °C. Assays in carrot juice with isolated yeasts and molds showed the ability of Meyerozyma guillermondii to induce texture modification and some isolates, e.g., Pichia guillermondii, resulted in gas production. Selected isolates able to induce spoilage are useful to test preservative treatments of fresh carrot juice under controlled conditions. View Full-Text

Research – The epidemiology of Shiga toxin-producing Escherichia coli serogroup O157 in England, 2009–2019

Cambridge Org

Shiga toxin-producing Escherichia coli (STEC) serogroup O157 is a zoonotic, foodborne gastrointestinal pathogen of major public health concern. We describe the epidemiology of STEC O157 infection in England by exploring the microbiological and clinical characteristics, the demographic and geographical distribution of cases, and examining changes in environmental exposures over 11 years of enhanced surveillance. Enhanced surveillance data including microbiological subtyping, clinical presentations and exposures were extracted for all cases resident in England with evidence of STEC O157 infection, either due to faecal culture or serology detection. Incidence rates were calculated based on mid-year population estimates from the Office of National Statistics (ONS). Demographics, geography, severity and environmental exposures were compared across the time periods 2009–2014 and 2015–2019. The number of cases reported to national surveillance decreased, with the mean cases per year dropping from 887 for the period 2009–2014 to 595 for the period 2015–2019. The decline in STEC O157 infections appears to be mirrored by the decrease in cases infected with phage type 21/28. Although the percentage of cases that developed HUS decreased, the percentage of cases reporting bloody diarrhoea and hospitalisation remained stable. The number of outbreaks declined over time, although more refined typing methods linked more cases to each outbreak. Integration of epidemiological data with microbiological typing data is essential to understanding the changes in the burden of STEC infection, assessment of the risks to public health, and the prediction and mitigation of emerging threats.

Research – Impact of Quercetin against Salmonella Typhimurium Biofilm Formation on Food–Contact Surfaces and Molecular Mechanism Pattern

MDPI

Quercetin is an active nutraceutical element that is found in a variety of foods, vegetables, fruits, and other products. Due to its antioxidant properties, quercetin is a flexible functional food that has broad protective effects against a wide range of infectious and degenerative disorders. As a result, research is required on food-contact surfaces (rubber (R) and hand gloves (HG)) that can lead to cross-contamination. In this investigation, the inhibitory effects of quercetin, an antioxidant and antibacterial molecule, were investigated at sub-MIC (125; 1/2, 62.5; 1/4, and 31.25; 1/8 MIC, μg/mL) against Salmonella Typhimurium on surfaces. When quercetin (0–125 μg/mL) was observed on R and HG surfaces, the inhibitory effects were 0.09–2.49 and 0.20–2.43 log CFU/cm2, respectively (p < 0.05). The results were confirmed by field emission scanning electron microscopy (FE-SEM), because quercetin inhibited the biofilms by disturbing cell-to-cell connections and inducing cell lysis, resulting in the loss of normal cell morphology, and the motility (swimming and swarming) was significantly different at 1/4 and 1/2 MIC compared to the control. Quercetin significantly (p < 0.05) suppressed the expression levels of virulence and stress response (rpoSavrA, and hilA) and quorum-sensing (luxS) genes. Our findings imply that plant-derived quercetin could be used as an antibiofilm agent in the food industry to prevent S. Typhimurium biofilm formation. View Full-Text