Role of Lactic Acid Bacteria as a Bio-sanitizer to Prevent Attachment of Listeria Monocytogenes on Deli Slicer Contact Surfaces, and the Influence of Listeria Innocua on the Attachment of L. Monocytogenes on Selected Materials Located in the Food-processing Environment

Listeria monocytogenes an important foodborne pathogen that continues to be a serious problem for the food industry. This pathogen contaminates food primarily during post-harvest in the food-processing environment. Its ecology in the food-processing environment is not well understood but previous research has demonstrated the ability of L. monocytogenes to survive on food contact surfaces after cleaning and disinfection. The current study explored the attachment of three lactic acid bacteria (LAB) strains, Lactobacillus animalis , Lb. amylovorus and Pediococcus acidilactici , their combination in a cocktail, and their influence to prevent the attachment of L. monocytogenes at room temperature by examining their cell surface hydrophobicity, total carbohydrates production and adherence capability to stainless steel coupons made from a deli slicer. Subsequently, the study evaluated the influence of L. innocua on the attachment of L. monocytogenes on stainless steel, and on aluminum surfaces. The hydrophobicity tests were performed according to microbial adhesion to solvent (MATS). Extracellular carbohydrates were quantified using a colorimetric method. Based on these tests, Lb. animalis exhibited the greatest hydrophobicity (26.3 %) and its adherence increased sharply from 24 to 72 hr, whereas Lb. amylovorus yielded the lowest hydrophobicity 3.86 % and was only weakly adherent. P. acidilactici with a hydrophobicity of 10.1 % adhered strongly. The attached LAB strains produced significantly (P \u3c 0.05) higher total carbohydrates than their planktonic counterparts, which is an important characteristic for attachment. Three separate conditions, LAB first, LAB and L. monocytogenes concurrently and L. monocytogenes inoculated first then LAB, were simulated to evaluate the ability of the LAB cocktail (10 8 CFU/ml) to competitively exclude L. monocytogenes (103 CFU/ml) on the surface of the stainless coupons. In all the three comparisons, the LAB cocktail was able to reduce the attachment of L. monocytogenes significantly (P \u3c 0.05). Thus, the LAB cocktail indicated attachment on stainless steel and bacteriostatic activity against L. monocytogenes attached on stainless steel. These properties may be used in manufacturing a bio-sanitizer geared to prevent the formation L. monocytogenes biofilm on food contact surfaces. Preliminary data showed L. innocua had a positive effect on the attachment of L. monocytogenes on stainless steel or aluminum surfaces

Intramuscular fatty acid profiles in farm animals vis-a-vis meat eating and nutritional quality: A Review

In regards with fast growing meat consumption in modernizing countries in the 20th Century, recommendations for a public healthier eating were formulated. It is assumed that an increasing consumption of meat whose fat composition is considered too high in saturated fatty acids (SFA) and too low in Polyunsaturated fatty acids (PUFA), constitutes a public health hazard. The main health risk associated with consumption of meat rich in SFA is that they are reported to contribute to the development of cardiovascular disease in human. This paper aims to review the existing information on some of the most important aspects of intramuscular fatty acid composition and metabolism in farm animals. Trends in healthy eating resulted in selection for leaner animals that has characterized the meat production systems in developed countries, affecting de facto meat eating and technological indices. Similar predictions would be drawn for emerging societies thus; more reflections are needed to deal with human health aspects of meat, without affecting its eating quality and technological processing. Keywords: Intramuscular fat, fatty acid profiles, meat quality, modern eating trend

A systematic literature review of milk consumption and associated bacterial zoonoses in East Africa

Consumption of unsafe animal-source foods is the major cause of foodborne disease outbreaks in low-income countries. Despite current knowledge of the threat posed by raw milk consumption to human health, people in many countries in East Africa still consume unboiled milk. This literature review explored the association between milk consumption and the occurrence of five milk-borne bacterial zoonoses: brucellosis, salmonellosis, campylobacteriosis, Escherichia coli infections, and tuberculosis. A search for literature published up to 1 October 2021 was conducted through the Web of Science, PubMed, and Scopus databases, using Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. The selection process yielded 65 articles describing studies conducted in East Africa 2010-2021, which were carefully scrutinized. The most investigated pathogen was Brucella spp. (54.5%), followed by E. coli (18.2%), Salmonella spp. (12.1%), Mycobacterium spp. (6.1%), and E. coli O157: H7 (6.1%). The most common predisposing factors for potential milk-borne disease outbreaks were consumption of contaminated raw milk, inadequate cold storage along the milk value chain, poor milk handling practices, and lack of awareness of the health risks of consuming unpasteurized milk. Thus, a tailor-made training program is needed for all milk value chain actors to enhance the safety of milk sold in informal markets, and a One Health approach should be applied. Future studies should employ more advanced diagnostic techniques and countries in East Africa should invest in modern diagnostic tools and equipment, both in hospitals and in local rural settings where most cases occur

MILK Symposium review: Microbiological quality and safety of milk from farm to milk collection centers in Rwanda

The aim of this study was to generate knowledge on the most important milk quality and safety attributes, including somatic cell count (SCC), total bacterial count (TBC), Escherichia coli, Salmonella, and Brucella spp. antibodies and antibiotic residues in milk in the chain from farm to milk collection center (MCC) in Rwanda. In addition, we investigated farm and management factors associated with high TBC, SCC, and Salmonella counts. Raw milk was sampled at the farm and MCC levels. Milk samples were taken from dairy farms linked to 2 selected MCC in each of the 4 provinces in Rwanda. In total, 406 bulk milk samples from 406 farms and 32 bulk milk samples from 8 MCC were collected and analyzed. Farm milk average SCC varied between 180 × 103 and 920 × 103 cells/mL, whereas average SCC in milk samples at MCC varied between 170 × 103 and 1,700 × 103 cells/mL. The mean milk TBC of different farms per MCC varied between 1.1 × 106 and 1.6 × 107 cfu/mL, whereas in milk samples from different MCC, the mean TBC ranged between 5.3 × 105 and 2.4 × 108 cfu/mL. The high TBC in milk from MCC suggests proliferation or recontamination of milk by bacteria during transportation. Escherichia coli was detected in 35 of 385 farm milk samples and ranged between 5 cfu/mL and 1.1 × 104 cfu/mL, whereas in milk samples from the MCC, it was detected in 20 out 32 samples varying between 5 cfu/mL and 2.9 × 103 cfu/mL. Overall farm prevalence of Salmonella in milk samples was 14%, but no milk samples from MCC were positive for Salmonella. Five out of 22 bulk milk samples from different MCC were positive for Brucella spp. antibodies, but no Brucella antibodies were detected in milk samples from farms. The prevalence of antibiotic residues as detected by the Delvotest SP NT (DSM, Delft, the Netherlands) was low: 1.3% in farm milk samples and undetected in MCC milk samples. Lack of a separate milking area was associated with high TBC, whereas offering of supplemental feeds, keeping data of past diseases, and an unhygienic milking area were associated with high SCC. Lack of teat washing before milking was the only factor associated with Salmonella contamination of milk at the farm level. This study indicated high TBC and SCC of milk samples at the farm and MCC levels, which indicates both microbial contamination of milk and poor udder health in dairy cows. Presence of E. coli, Salmonella, and Brucella antibodies in milk was common, but finding antibiotic residues in milk was uncommon

Mastitis in dairy cows in Rwanda

The milk sector in Rwanda can be made competitive through improved udder health resulting in higher milk yields. This thesis investigated prevalence and aetiology of subclinical mastitis (SCM) in dairy cows, antimicrobial resistance and molecular epidemiology of udder pathogens. Screening for SCM with California Mastitis Test (CMT) was done in 828 cows in 429 herds from five regions in Rwanda. Milk was sampled from udder quarters with CMT score ≥3. Herd bulk milk quality and safety was investigated to generate knowledge for quality control. Overall SCM prevalence was 70.4% on herd level, 66.3% on cow level and 39% on quarter level. Overall 73.9% of all cultured milk samples were bacteriologically positive. Non-aureus staphylococci (NAS) followed by Staphylococcus (S.) aureus were the predominant pathogens. Staphylococcus chromogenes, epidermidis and sciuri were the most prevalent NAS. There was a high diversity of S. aureus sequence types, with both humans and cows as possible sources. Penicillin resistance exceeded 60% in all staphylococci. Among S. aureus isolates, 83.3% were resistant to penicillin, 100% to clindamycin and 20% to tetracycline. Main risk factors for SCM with implications on management routines included housing of cows in individual cattle kraal and on earthen floor, poor hygiene (hands, cows and milking area), absence of foremilk stripping, increasing stage of lactation, Holstein breed, lack of calf suckling and of feeding after milking. Total bacterial count and somatic cell count was high in milk from farms and milk collection centers, which indicate poor udder health and hygiene and contamination along the transport chain. Presence of Escherichia coli, Salmonella spp. and brucella antibodies in milk was common. Antimicrobial residues in milk was uncommon. In conclusion, SCM is common in dairy herds in Rwanda and the majority of causative pathogens exhibited penicillin resistance. The high microbial load has implications for milk quality, processability and public health. The high genetic diversity of S. aureus should be considered in future studies of disease spread. A mastitis control plan is recommended

Aetiology and prevalence of subclinical mastitis in dairy herds in peri-urban areas of Kigali in Rwanda

The aim of this cross-sectional study was to evaluate the prevalence of subclinical mastitis (SCM) and associated risk factors in dairy cows in peri-urban areas of Kigali, Rwanda, and identify causative udder pathogens. A sample of 256 cows from 25 herds was screened with the California Mastitis Test (CMT), and udder quarters with CMT score >= 3 (scale 1-5) were milk sampled for culture and final bacteriological identification with matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS). All resultant staphylococci species were tested for beta-lactamase production with the clover leaf method. In parallel, herd bulk milk somatic cell count (SCC) of each herd was analysed using a portable device, the DeLaval cell counter. The prevalence of SCM was 43.1% at quarter level and 76.2% at cow level based on CMT test. Multiparous, Holstein cows were 2.50 (C.I = 1.32-4.71) and 10.08 (C.I = 1.54-66.13) times more likely to contract SCM infection than primiparous animals or cows of other breeds, respectively. The median and mean SCC of all herds were 1108 x 10(3) cells/mL and 1179 x 10(3) cells/mL, respectively. The most prevalent pathogens were non-aureus staphylococci (NAS; 40.2%) followed by Staphylococcus aureus (22%) and less prevalent pathogens (6%). Samples with no growth or contamination constituted 30.4% and 1.4% of the diagnoses, respectively. The most prevalent species within NAS were S. epidermidis (38.2%) followed by S. sciuri (19.5%), S. chromogenes (9.8%), and nine less prevalent NAS species (32.5%). Out of 209 staphylococci isolates, 77% exhibited beta-lactamase production. The study shows that there is high prevalence of SCM and high herd bulk milk SCC in herds in Kigali, indicating udder health problems in dairy cows. Additionally, beta-lactamase production among staphylococci species was common. Improved milking hygiene and application of biosecurity measures, or a complete mastitis control plan, is required to lower the prevalence of SCM and minimize the spread of pathogens among dairy cows