The microbial quality of ostrich carcases produced in a export-approved South African abattoir

The aim of this study was to evaluate the microbial quality of ostrich carcases produced in a South African export-approved ostrich abattoir. Ninety surface samples were collected on 30 ostrich carcases at three processing points in the abattoir: post-flaying, post-evisceration and post-chilling. Carcase samples were evaluated for the Aerobic Plate Count (APC), Pseudomonas spp., Enterobacteriaceae, Staphylococcus aureus and for the presence of Escherichia coli and presumptive Salmonella spp. One hundred isolates obtained from the APC were identified. The mean log CFU/cm2 and standard deviations for surface counts at post-flaying, post-evisceration and post-chilling processing points respectively were: 4.32 ±0.62, 4.21 ±0.63 and 4.57 ±0.48 for the APC; 2.82 ±1.65, 2.86 ±1.53 and 3.75 ±0.94 for Pseudomonas spp.; 2.89 ±0.78, 2.90 ±0.53 and 2.38 ±0.67 for S. aureus and 2.55 ±1.53, 2.78 ±1.31 and 2.73 ±1.46 for Enterobacteriaceae. No significant differences were detected between the mean log counts of the post-flaying and post-evisceration processing points for the above-mentioned bacterial counts. However, statistically significant differences were detected between the mean log CFU/cm2 counts for post-flaying and post-chilling and between the counts for the post-evisceration and the post-chilling processing points for the APC, Pseudomonas spp. and S. aureus. The trend was towards a marginal increase for the APC, and a negligible decrease for S. aureus counts obtained on samples collected post-chilling. However, there was an increase of practical significance for Pseudomonas spp. counts obtained post-chilling. Seventeen out of 90 (18.8%) samples were positive for E. coli in terms of samples collected and 13 out of 30 (43%) in terms of carcases sampled. Log CFU/cm2 counts for E. coli positive samples ranged from 1.0 to 3.79, with a mean log count of 2.15. Most of the samples, which were positive for E. coli were collected post-evisceration. The prevalence rate for presumptive Salmonella spp. on both Brilliant Green Agar and Xylose Lysine Desoxycolate Agar was 15.5% in terms of samples collected and 23.3% in terms of carcases sampled. Most of the positive samples were collected post-evisceration. The proportional distribution of one hundred (100) bacterial isolates identified was Enterobacteriaceae: 57%, Acinetobacter spp.: 24 %, Pseudomonas spp.: 11%, Aeromonas spp.: 3%, Micrococcus spp.: 3%, Staphylococcus spp.: 1% and yeasts: 1%. Enterobacteriaceae were the predominant bacteria in terms of the total number of isolates identified per processing point and for the whole study.Dissertation (MMedVet (Hyg))--University of Pretoria, 2001.Paraclinical Sciencesunrestricte

Virulence profiling of shiga toxin-producing Escherichia coli O111 : NM isolates from cattle

Shiga toxin-producing Escherichia coli (STEC) O111:NM is an important serotype that has been incriminated in disease outbreaks in the United States. This study characterized cattle STEC O111:NM for virulence factors and markers by PCR. Major conclusions are that STEC O111:NM characterized in this study lacks stx2 and the full spectrum of nle gene markers, and it has an incomplete OI-122.http://aem.asm.org/am2013mn201

Detection of tet(M) gene from raw milk by rapid DNA extraction followed by a two-step PCR with nested primers.

The likelihood that milk and milk products may act as a vehicle for antibiotic-resistant bacterial genes has become a concern to the food industry and a public health issue, and the demand for rapid tests has increased. The purity of DNA extracted from food samples is a key issue in the sensitivity and usefulness of biological analyses, such as PCR for pathogens and nonpathogens. A rapid, phenol-chloroform free method based on a modification of a sodium iodide DNA extraction, followed by a two-step PCR was developed for direct detection of the tet(M) gene in milk samples within a single working day. This study compares the proposed method with a traditional phenol solvent extraction method and with a commercial kit (QIAamp DNA blood mini kit, Qiagen). The three DNA extraction methods were used to ensure access to the tet(M) gene from 1 ml of raw milk, inoculated with a strain of Enterococcus faecalis, which carries the tet(M) gene. The proposed method, followed by a two-step PCR with nested primers specific for the tet(M) gene, was able to reach a detection limit below 10 CFU/ml in less than 4 h, including the two amplification cycles, thus outperforming in sensitivity and rapidity both the traditional and the commercial method

Enterotoxin production by Staphylococcus aureus isolated from mastitic cows.

Staphylococcus aureus is an important cause of mastitis in cows. The ability of S. aureus strains to produce one or more enterotoxins in milk and dairy products is linked to staphylococcal food poisoning. To determine whether staphylococci causing bovine mastitis could cause human foodborne intoxication, the production of staphylococcal enterotoxins A through D (SEA, SEB, SEC, and SED) by 160 S. aureus isolates was evaluated with the use of a reverse passive latex agglutination enterotoxin kit. All S. aureus strains were isolated over a 9-month period from 2,343 routine submissions of a composite quarter collection of individual mastitic cows at 18 dairy farms in the San Joaquin Valley in California. Prior to enterotoxin detection, isolates were grown by a method that enhances the in vitro synthesis of enterotoxin. Twenty-two of 160 S. aureus isolates produced enterotoxin. Seven produced SEC, 12 produced SED, and 3 produced both SEC and SED. None of the isolates produced SEA or SEB

Is EU regulation on the use of antioxidants in meat preparation and in meat products still cutting edge?

The use of antioxidants in meat preparation and meat products is highly debated. Regulations define the use of antioxidants mostly in terms of the age-old subdivision between meat preparations and meat products. Best practices are not well represented in regulations. Antioxidants for foodstuffs during processing or before packing protect colour, aroma and nutrient content. As regards food safety regulations, long-term efforts have been made in terms of food standards, food control systems, food legislation and regulatory approaches. These have, however, generated several questions on how to apply the law to diverse food businesses. To answer these questions, a thorough examination of the EU legislator’s choices for food additives and definitions is provided and discussed in relation to factors affecting microbial growth. The paper highlights the regulatory aspects along with the correct application and interpretation of the norms.https://link.springer.com/journal/2172021-01-07hj2020Paraclinical Science

Evolution under different storage conditions of anomalous blue coloration of Mozzarella cheese intentionally contaminated with a pigment-producing strain of Pseudomonas fluorescens

Several widespread occurrences of anomalous blue coloration of Mozzarella cheese have been recorded in the United States and some European countries. Official laboratory analysis and health authorities have linked the occurrences to contamination of the processing water with strains of Pseudomonas fluorescens, although several experts questioned how to unequivocally link the blue color to the presence of the microorganism. To establish a method to determine whether a given Pseudomonas spp. strain is responsible for the defect and study the evolution of the coloration under different storage conditions, we developed an in vitro system for the evaluation of blue coloration of Mozzarella cheese intentionally contaminated with strains of P. fluorescens. The purpose of the system was to determine whether P.fluorescens strains, isolated from Mozzarella cheese with anomalous blue coloration, were able to reproduce the blue coloration under controlled experimental conditions. Thirty-six trials of experimental inoculation of Mozzarella cheese in different preservation liquids were conducted using various suspensions of P.fluorescens (P. fluorescens ATCC 13525, P.fluorescens CFBP 3150, and P. fluorescens 349 field strain isolated from blue-colored Mozzarella cheese) at different concentrations and incubated at different temperatures. Growth curves of all tested P.fluorescens strains demonstrated that after 3 d of incubation the concentration was generally >106 cfu/g of Mozzarella cheese incubated in either tryptic soy broth (control) or conditioning brine. Prolonged incubation for 5 d at either 20°C or 8°C led to concentrations up to 109 cfu/g of Mozzarella cheese incubated in tryptic soy broth and up to 108 cfu/g of Mozzarella cheese incubated in preservation liquid. All Mozzarella cheeses inoculated with the field strain of P. fluorescens, except those opened 1 h after packaging and stored at 8°C, showed the characteristic anomalous blue coloration, which appeared from 1 to 72 h after opening the packaging, and was proportional to colony count, duration of storage, and storage temperature. With the proposed system, which enabled a larger number of samples to be analyzed under controlled experimental conditions and a large amount of data to be generated in a short time, we described precisely how and under which conditions the presence of P. fluorescens in Mozzarella cheese is responsible for the anomalous blue coloration. The system will help producers intercept contaminated batches and help consumers avoid the conditions under which the defect can appear.Grants from Fondazione Cassa di Risparmio di Perugia (Italy) and from the Ministero degli Affari Esteri, Direzione Generale per la Promozione e Cooperazione Culturale (Rome, Italy),http://www.journals.elsevier.com/journal-of-dairy-sciencehb2017Paraclinical Science

New trends in meat packaging

The term ‘packaging’ refers to the technological intervention aimed at the protection of food from a variety of factors, which provokes the product detriment. Packaging is considered as one of the most interesting technological aspects and a constantly evolving issue in food production. This paper aims at the evaluation of the properties of packaging currently used in the meat industry and analyses the advantages, the disadvantages and the microbiota involved. Packaging is a coordinated system, which prepares the products for transportation, distribution, storage, marketing and consumption. Even if several packaging alternatives are proposed, the common purpose is to guarantee high standards, yet maintaining the required characteristics as long as possible. Meat is a dynamic system with a limited shelf-life and the nutritional and sensory properties may change during storage due to microbial activity and physical or chemical changes. Microbial spoilage, for instance, determines an impact in meat, producing unattractive odours, flavours, discolouration, gas and slime.EFSAam2021Paraclinical Science

Molecular profiling and antimicrobial resistance of Shiga toxin-producing Escherichia coli O26, O45, O103, O121, O145 and O157 isolates from cattle on cow-calf operations in South Africa

In this study, 140 cattle STEC isolates belonging to serogroups O157, O26, O145, O121, O103 and O45 were characterized for 38 virulence-associated genes, antimicrobial resistance profiles and genotyped by PFGE. The majority of isolates carried both stx1 and stx2 concurrently, stx2c, and stx2d; plasmidencoded genes ehxA, espP, subA and saa but lacked katP and etpD and eaeA. Possession of eaeA was significantly associated with the presence of nle genes, katP, etpD, ureC and terC. However, saa and subA, stx1c and stx1d were only detected in eaeA negative isolates. A complete OI-122 and most non- LEE effector genes were detected in only two eaeA positive serotypes, including STEC O157:H7 and O103:H2. The eaeA gene was detected in STEC serotypes that are commonly implicated in severe humans disease and outbreaks including STEC O157:H7, STEC O145:H28 and O103:H2. PFGE revealed that the isolates were highly diverse with very low rates of antimicrobial resistance. In conclusion, only a small number of cattle STEC serotypes that possessed eaeA, had the highest number of virulenceassociated genes, indicative of their high virulence. Further characterization of STEC O157:H7, STEC O145:H28 and O103:H2 using whole genome sequencing will be needed to fully understand their virulence potential for humans.This manuscript is part a dissertation submitted in the Veterinary Public Health section, Department of Paraclinical Sciences, University of Pretoria, in partial fulfilment of the requirements for the degree of Master of Science (Veterinary Science). (http://hdl.handle.net/2263/65499)The Gauteng Department of Agriculture and Rural Development (GDARD) (Grant No. FY 2013/14‐A0W907), the Global Disease Detection (GDD) Program of the Centers for Disease Control and Prevention (CDC) (Grant No. 1U2GGH001874‐01) and the National Research Foundation (NRF) of South Africa Thuthuka (TTK13062619943), Research Technology (RTF14012762427) Funds.https://www.nature.com/srepam2019Paraclinical Science

Growth inhibition of selected microorganisms by an association of dairy starter cultures and probiotics

Several growth curves for selected pathogens and hygiene indicators alone and vs selected dairy starter cultures (LAB) and commercial probiotics have been performed. All strains for LAB and commercial probiotics were inoculated as pure cultures into skim milk to get an initial cocci:bacilli:enterocci ratio of 2:1:1 and a concentration of approx 107 cfu mL–1 until challenge vs selected pathogens and hygiene indicators. Selected pathogens came from the collection of the Laboratorio di Ispezione degli Alimenti di O.A. or were reference strains (Escherichia coli, CSH26 K12, Staphylococcus aureus, 27R, Salmonella Derby 27, Pseudomonas fluorescens ATCC 13525, Listeria innocua ATCC 33090). Each strain was inoculated into skim milk to get an initial concentration of approx 106 cfu mL–1. Growth curves in skim milk for the following challenges were studied: i) sterility control; ii) association LAB; iii) association of LAB vs each selected pathogen or hygiene indicator; iv) selected pathogen or hygiene indicator alone. The challenges were carried out in BHI broth and in skim milk at 37°C. The highest reduction was observed in milk but in general the association of LAB and the probiotic was able to limit the growth of pathogens and hygiene indicators.http://www.aspajournal.itindex.php/ijas/indexam201

Two screening assays to detect vancomycin-resistant Enterococcus spp.

Enterococci have become major nosocomial pathogens. An increasing number of these infections are as a result of vancomycin-resistant enterococci. Accurate detection of vancomycinresistant enterococci (VRE) is important, so that appropriate therapy and infection control measures may be instituted, including veterinary surveillance. Two screening assays to detect vancomycin resistance in enterococci are proposed. Barnes Basal Medium agar (Ba) and Brain Heart Infusion (BHI) broth (plus 1% TTC-2,3,5-triphenyltetrazolium chloride) with several concentrations of vancomycin were used in this work. Five Enterococcus casseliflavus strains with low-level resistance to vancomycin (4 g/mL) were used. Both media were able to quickly detect the breakpoint of the vancomycinresistant strains used in this work, and also provided insight into the dynamics of the antibiotic effect at a low concentration on the tested bacterial suspensions.European Food Safety Authority (EFSA).https://www.mdpi.com/journal/microbiolresam2023Paraclinical Science