The development and validation of a bacteriological screening test for antimicrobial residues in eggs

Microbiological screening of antimicrobial residues in eggs needs special attention because of the high level of naturally occurring inhibitors contained in eggs which often lead to false positive results. However, it was discovered that heating egg samples at 800C for 10 minutes inactivated the inhibitors. The new bacteriological screening test for antimicrobial residues in eggs which was developed during this study, contains viable spores of Geobacillus stearothermophilus which are sensitive to antimicrobial residues including beta-lactams, tetracycline’s and macrolides. The new test method was validated based on the comparison with a reference method, namely the Kundrat micro-screening four-plate test,1 and published literature of another standard reference method, the Premi®Test. A preliminary trial was conducted on 36 hens that were given therapeutic oral doses of overthe- counter antimicrobials daily for seven days with one of eleven antimicrobials based on the manufacturer’s recommendations. Eggs were collected from the hens during and after treatment and tested for the presence or absence of antimicrobial residues. Several performance criteria and minimum detection concentrations were estimated and discussed. Some agreements and differences were found between the new and the reference tests with the new test being more sensitive to beta-lactams, tetracyclines and macrolides than the Kundrat and Premi®Test on the average. The use of florfenicol and norfloxacin in laying hens is banned and therefore there are no maximum residue limits (MRL) or published Premi®Test values. For meat, the MRL is 100mg/kg. It was therefore concluded that the new screening test could be used for routine screening of antimicrobial residues in eggs. A two seasonal survey was also conducted to determine the prevalence of antimicrobial residues in commercial chicken eggs in Tshwane area of Gauteng Province, South Africa. Although the season did not impact statistically on the antibiotic residues found in the eggs; eggs sold at the roadside (informal businesses), certain egg brands, and those sold at lower prices were found to be more likely to contain antibiotic residues than those obtained from formal outlets and at higher prices. CopyrightDissertation (MSc)--University of Pretoria, 2011.Production Animal Studiesunrestricte

Bacterial species from retailed poultry eggs in Tshwane, South Africa : implication for consumers

Food safety is an important public health issue and governments across the world are intensifying their efforts to improve the quantity, quality and the safety of national food supplies. Bacteria, especially Salmonella species, present in or on chicken meat and hens’ eggs in particular are the most common causes of food poisoning and the major sources of human salmonellosis. Literature reveals little information on the risk factors for salmonellae infection in Africa. The aim of this study was to determine which, if any, bacteria, especially Salmonella species, are present in and on hens’ eggs. Representative bacterial colonies were confirmed with Gram staining and then identified using the MALDI-TOF Biotyper assay. The genera identified were Escherichia coli (34%), Enterococcus faecalis (14%), Proteus mirabilis (9%), Klebshiella pneumoniae (7%), Salmonella Typhimurium (6%), Enterobacter cloacae (1%), Stenotrophomonas maltophilia (0.6%), Salmonella Dublin (0.6%) and Salmonella Braenderup (0.2%). Raw hens’ eggs and products containing raw hens’ eggs may contain pathogenic bacteria, thereby exposing a large number of consumers to the risk of contracting food poisoning when undercooked or uncooked hens’ eggs are consumed. SIGNIFICANCE : • Enterobacteriaceae counts are used as an indicator to evaluate the hygienic quality of food. • The presence of Salmonella species and other Enterobacteriaceae in raw hens’ eggs poses a health risk to consumers. • Any product in which raw eggs are used must be provided with a conspicuous label stating that it may contain pathogenic bacteria.Funding of the project was through the research funds of F.S.B. and E.M.B.http://www.sajs.co.zaam2018Food ScienceParaclinical Science

Potency and selectivity indices of acetone leaf extracts of nine selected South African trees against six opportunistic Enterobacteriaceae isolates from commercial chicken eggs

BACKGROUND : The rise in antimicrobial resistance in a plethora of nosocomial and opportunistic bacterial pathogens often isolated from commercial eggs, poses a serious public health concern. The existence of these contaminants may also serve as a drawback in the current efforts of improving the well-being of immunocompromised patients. The aim of this study was to determine the efficacy of plant extracts that had good activity on Escherichia coli in previous word on pathogens isolated from eggs for possible use in combating pathogens from eggs. METHODS : Acetone leaf extracts of nine trees with good activities against Escherichia coli were tested for their in vitro antibacterial activity against six opportunistic bacterial isolates from commercial eggs (Stenotrophomonas maltophilia, Klebsiella pneumoniae, Salmonella serotype Typhimurium, Proteus mirabilis, Enterobacter cloacae and Escherichia coli) using a serial microdilution method with tetrazolium violet as indicator of growth. Cytotoxicity was determined using a tetrazolium-based colorimetric assay against Vero kidney cells, and selectivity index calculated. RESULTS : The MIC values range of the different extracts against Stenotrophomonas maltophilia was 0.08-0.31 mg/ml, Klebsiella pneumonia 0.08-0.63 mg/ml, Salmonella ser. Typhimurium 0.08-0.63 mg/ml, Proteus mirabilis 0.02-1.25 mg/ ml, Enterobacter cloacae 0.08-0.31 mg/ml and Escherichia coli 0.08-0.16 mg/ml respectively. Escherichia coli was the most sensitive while Proteus mirabilis was most resistant pathogen to the different test extracts, with mean MIC values of 0.08 mg/ml and 0.46 mg/ml respectively. Cremaspora triflora extracts had good activity against all the pathogenic egg isolates, with the exception of Proteus mirabilis. Maesa lanceolata and Elaeodendron croceum had the best total antibacterial activity (TAA), while generally the selectivity index of the extract was low (SI < 1). CONCLUSION : The exceptional activity of C. triflora extracts suggests that the plant has potential as a therapeutic agent against some members of the Enterobacteriaceae. Further pharmacological investigations may be interesting in the search for new antimicrobial leads.This manuscript is an output of a Ph. D. research project.The National Research Foundation of South Africa (Eloff IPPR 953991), the South African Medical Research Council and the University of Pretoria.http://www.biomedcentral.com/bmccom/plementalternmedam2017Food ScienceParaclinical Science

Salmonella enterica Newserovar Abeokuta Genome Sequence, Strain OG19FER4 Isolated from Poultry Feed in Nigeria.

This report announces the genome of a newly confirmed Salmonella serovar (Salmonella enterica serovar Abeokuta) that was isolated from a poultry feed sample collected on a farm in Abeokuta, capital of Ogun State in Nigeria. Salmonella Abeokuta has not been identified outside Nigeria, nor does it appear to be a cause for concern for animal and human health