Seasonal variation of Salmonella enterica prevalence in milk and cottage cheese along the dairy value chain in three regions of Ethiopia.

Seasonal fluctuations influence foodborne illness transmission and affect patterns of microbial contamination of food. Previous investigations on the seasonality of Salmonella enterica prevalence in dairy products in Ethiopia have been minimal. However, such data are needed to inform strategic development of effective interventions to improve food safety, as seasonal differences may affect intervention strategies. This study was conducted to identify differences in the prevalence of Salmonella in milk and cheese samples between wet and dry seasons. A longitudinal study design was utilized with a random sampling occurring during both dry and wet seasons. A total of 448 milk and cottage cheese samples were collected from Oromia, Sidama, and Amhara regions. Samples were tested for Salmonella using the ISO 6579-1: 2008 method, followed by PCR confirmation. A chi-square test was conducted to assess the significance of differences in the prevalence of Salmonella in the samples between the two seasons. Results from this study showed a higher prevalence of Salmonella in all sample types during the dry season (P < 0.05). Moreover, when comparing raw milk, pasteurized milk, and cottage cheese samples, a significant difference was observed in Salmonella prevalence from raw milk samples (27.08%) collected in the Oromia region. Additionally, data showed a significantly higher prevalence of Salmonella in samples collected from raw milk producers (29.17%) during the wet season (P < 0.05). This study indicates that in order to enhance the safety of dairy products in Ethiopia, comprehensive, long-term awareness building on hygienic milk production and handling that consider seasonal influence is warranted. Supplementary Information: The online version contains supplementary material available at 10.1186/s40550-024-00108-4.

Hygienic status of beef butcher shop facilities and antibiotic resistance profile of Salmonella enterica in Ethiopia.

The microbiological quality of meat is influenced by the conditions of hygiene prevailing during production and handling. Thus, this study aimed to assess the prevalence of Salmonella enterica and its antimicrobial resistance, load of hygiene indicator bacteria including E. coli (ECC), coliforms (CC), total coliform (TCC), Enterobacteriaceae (EB) and aerobic plate count (APC), and meat handler's food safety knowledge and hygiene practices in butcher shops in two cities, Addis Ababa and Hawassa in Ethiopia, during 2020 and 2021. A total of 360 samples of beef carcasses (n = 120), knives (n = 60), chopping boards (n = 60), weighing balance (n = 60), and personnel's hands (n = 60) were randomly collected for microbial analysis. Besides, 120 participants were selected to participate in a food safety knowledge and hygiene practices assessment. The S. enterica isolates were identified by agglutination test followed by qPCR targeting invA gene. Phenotypic antimicrobial resistance profiles of S. enterica were determined using disk diffusion assays as described in CLSI. The ECC, CC, TCC, EB, and APC populations were quantified by plating onto petrifilm plates. A structured questionnaire was used to determine food safety knowledge and hygiene practices of participants. Overall prevalence of S. enterica was 16.7% (95% CI, 8.3-26.7) and location seems to have no effect (p = 0.806). Only 20% of the S. enterica were resistant to ampicillin and tetracycline. However, the majority (80%) of S. enterica isolates were susceptible to the panel of 11 antimicrobials tested. The overall mean ± SD (log CFU/cm2) of ECC, CC, TCC, EB, and APC were 4.31 ± 1.15; 4.61 ± 1.33; 4.77 ± 1.32; 4.59 ± 1.38 and 5.87 ± 1.52, respectively. No significant difference (p = 0.123) in E. coli contamination was observed between samples of beef carcasses and chopping boards. The EB contamination showed no significant difference (p > 0.05) among sample sources. The APC contamination levels on beef carcass were significantly higher (p > 0.05) than other sample sources. A total of 56% (95% CI: 46.7 - 65.0) of the participants had poor knowledge and 65% (95% CI: 56.7 - 73.3) had poor hygiene practices towards food safety. This study highlighted the poor hygiene status of butcher facilities with a potential risk of beef safety. Thus, appropriate food safety control strategies and inspection is needed at retail establishments.

Prevalence and associated risk factors for Salmonella enterica contamination of cow milk and cottage cheese in Ethiopia.

Animal sourced foods, such as dairy products, are common sources of Salmonella enterica, a foodborne pathogen of increasing global concern, particularly in developing countries. In Ethiopia, most data on the prevalence of Salmonella in dairy products is highly varied and limited to a specific region or district. Furthermore, there is no data available on the risk factors for Salmonella contamination of cow milk and cottage cheese in Ethiopia. This study was therefore conducted to determine the presence of Salmonella throughout the Ethiopian dairy value chain and to identify risk factors for contamination with Salmonella. The study was carried out in three regions of Ethiopia, including Oromia, Southern Nations, Nationalities and Peoples, and Amhara during a dry season. A total 912 samples were collected from milk producers, collectors, processors, and retailers. Samples were tested for Salmonella using the ISO 6579-1: 2008 method, followed by PCR confirmation. Concurrent with sample collection, a survey was administered to study participants to identify risk factors associated with Salmonella contamination. Salmonella contamination was highest in raw milk samples at the production (19.7%) and at milk collection (21.3%) levels. No significant difference in the prevalence of Salmonella contamination among regions was detected (p > 0.05). Regional differences were apparent for cottage cheese, with the highest prevalence being in Oromia (6.3%). Identified risk factors included the temperature of water used for cow udder washing, the practice of mixing milk lots, the type of milk container, use of refrigeration, and milk filtration. These identified factors can be leveraged to develop targeted intervention strategies aimed at reducing the prevalence of Salmonella in milk and cottage cheese in Ethiopia.

Investigation on Salmonella enterica, Escherichia coli, and coliforms in beef from Ethiopian abattoirs: A potential risk of meat safety.

The aims of this study were to determine the prevalence of Salmonella enterica (S. enterica) antimicrobial resistance based upon phenotypic assessment, and level of sanitation indicator organisms from 150 beef carcasses collected from three representative abattoirs in eastern, central, and southern Ethiopia. Samples were screened for S. enterica prevalence following the U.S. Department of Agriculture Microbiology Laboratory Guidebook (MLG) and confirmed by real-time PCR. The S. enterica isolates were phenotypically evaluated for susceptibility to a panel of 13 antimicrobials using disk diffusion method as described in Clinical and Laboratory Standard Institutes guidelines. In addition, the coliform, total coliform, and generic E. coli populations were quantified by plating onto E. coli/coliform petrifilms. A total of 45 isolates of S. enterica were confirmed using real-time PCR. The overall prevalence of S. enterica at the carcass level was 22.7% (95% CI, 16.0-30.0). However, based on the sampling points, S. enterica prevalence detected on hides was 13.3% (95% CI, 8.0-18.7), pre-evisceration was 12.0% (95% CI, 7.3-17.3), and post-evisceration was 4.7% (95% CI, 1.3-8.0). The prevalence of S. enterica was significantly lower on post-evisceration as compared to hides (p = .009) and pre-evisceration (p = .022). No differences were detected for the prevalence of S. enterica between abattoirs (p = .346). Finally, the prevalence of S. enterica was highest during the wet season (p = .011). The overall mean log CFU/cm2 ± SD of generic E. coli, coliform, and total coliform counts were 4.55 ± 0.99, 4.91 ± 1.13, and 4.98 ± 1.09, respectively. About 20% of S. enterica exhibited phenotypic multidrug resistant. The most frequently detected resistance was to Tetracycline (28.9%), followed by Streptomycin (22.2%) and Sulfisoxazole (20.0%). The data from this study highlight the need to implement interventions on improvement of sanitary practices in abattoirs.

Genotypic and Phenotypic Characterization of Antimicrobial Resistance Profiles in Non-typhoidal Salmonella enterica Strains Isolated From Cambodian Informal Markets.

Non-typhoidal Salmonella enterica is a pathogen of global importance, particularly in low and middle-income countries (LMICs). The presence of antimicrobial resistant (AMR) strains in market environments poses a serious health threat to consumers. In this study we identified and characterized the genotypic and phenotypic AMR profiles of 81 environmental S. enterica strains isolated from samples from informal markets in Cambodia in 2018-2019. AMR genotypes were retrieved from the NCBI Pathogen Detection website (https://www.ncbi.nlm.nih.gov/pathogens/) and using ResFinder (https://cge.cbs.dtu.dk/services/) Salmonella pathogenicity islands (SPIs) were identified with SPIFinder (https://cge.cbs.dtu.dk/services/). Susceptibility testing was performed by broth microdilution according to the Clinical and Laboratory Standards Institute (CLSI) standard guidelines M100-S22 using the National Antimicrobial Resistance Monitoring System (NARMS) Sensititre Gram Negative plate. A total of 17 unique AMR genes were detected in 53% (43/81) of the isolates, including those encoding tetracycline, beta-lactam, sulfonamide, quinolone, aminoglycoside, phenicol, and trimethoprim resistance. A total of 10 SPIs (SPI-1, 3-5, 8, 9, 12-14, and centisome 63 [C63PI]) were detected in 59 isolates. C63PI, an iron transport system in SPI-1, was observed in 56% of the isolates (n = 46). SPI-1, SPI-4, and SPI-9 were present in 13, 2, and 5% of the isolates, respectively. The most common phenotypic resistances were observed to tetracycline (47%; n = 38), ampicillin (37%; n = 30), streptomycin (20%; n = 16), chloramphenicol (17%; n = 14), and trimethoprim-sulfamethoxazole (16%; n = 13). This study contributes to understanding the AMR genes present in S. enterica isolates from informal markets in Cambodia, as well as support domestic epidemiological investigations of multidrug resistance (MDR) profiles.

Prevalence of Salmonella enterica Isolated from Food Contact and Nonfood Contact Surfaces in Cambodian Informal Markets.

ABSTRACT: The lack of hygiene and sanitation practices and insufficient infrastructure in Cambodian informal markets may increase the risk of food contamination, specifically raw vegetables, which in turn may increase the chances of contracting a foodborne disease. The aims of this study in informal markets in Cambodia were (i) to quantify the prevalence of Salmonella enterica based upon differences in season of the year (rainy versus dry), surface types (food contact surfaces versus nonfood contact surfaces), and location of vendors within the market (inside versus outside) and (ii) to characterize S. enterica serotype prevalence. A total of 310 samples were screened for S. enterica prevalence following the U.S. Department of Agriculture guidelines, and results were confirmed by PCR assay. Whole genome sequencing was used to determine the serotype for each isolate in silico using SeqSero 1.0 on draft genomes. A total of 78 samples were confirmed positive for S. enterica. During the dry season, S. enterica was more prevalent on food contact surfaces than on nonfood contact surfaces (estimated probability of detection [confidence interval]: 0.41 [0.25, 0.59] and 0.17 [0.08, 0.32], respectively; P = 0.002), but no differences were apparent in the rainy season. No differences in S. enterica prevalence were found based on location within the market (P = 0.61). Sixteen S. enterica serotypes were detected across multiple surfaces. The most common S. enterica serotypes were Rissen (18 isolates), Hvittingfoss (11), Corvallis (10), Krefeld (8), Weltevreden (6), and Altona (6). Accurate data on the prevalence of S. enterica in informal markets are crucial for the development of effective surveillance and implementation of suitable intervention strategies at the domestic level, thus preventing foodborne illness.

Investigating Salmonella enterica, Escherichia coli, and Coliforms on Fresh Vegetables Sold in Informal Markets in Cambodia†.

ABSTRACT: Vegetables in Cambodia are commonly sold in informal markets lacking food safety standards and controls. Current data on microbial contamination of vegetables in Cambodian informal markets are limited. The purpose of this study was to investigate Salmonella enterica and indicator organisms (Escherichia coli and coliforms) on the surface of fresh vegetables sold in informal markets in Cambodia. Samples of loose-leaf lettuce, tomatoes, and cucumbers were collected from 104 vendors at four informal markets in Battambang and Siem Reap provinces during the rainy and dry seasons. Detection methods for S. enterica were adapted from the U.S. Food and Drug Administration's Bacteriological Analytical Manual. Coliform and E. coli populations were quantified by plating onto E. coli/coliform count plates. S. enterica was most prevalent on lettuce during the dry season (56.5%, 95% confidence interval [CI] [41.0, 70.8]) than during the rainy season (15.4%, 95% CI [7.5, 29.1]), whereas no significant seasonal differences were apparent for tomatoes and cucumbers. Regardless of season, levels of S. enterica were highest on lettuce (5.7 log CFU/g, 95% CI [5.5, 5.9]), relative to cucumbers (4.2 log CFU/g, 95% CI [3.8, 4.6]) and tomatoes (4.3 log CFU/g, 95% CI [4.1, 4.6]). For E. coli, prevalence was higher during the rainy season (34.0%, 95% CI [25.4, 43.8]) than during the dry season (9.1%, 95% CI [4.9, 16.5]), with the highest prevalence estimated on lettuce. Coliform levels on lettuce and tomatoes were greater during the rainy season (6.3 and 5.3 log CFU/g, 95% CI [5.7, 6.8] and [4.7, 5.8], respectively) than during the dry season (5.2 and 3.9 log CFU/g, 95% CI [4.7, 5.7] and [3.4, 4.4], respectively). These results indicate seasonal patterns for microbial prevalence in lettuce and an overall high level of bacterial contamination on raw vegetables sold in Cambodian informal markets.

Draft Genome Sequences of 81 Salmonella enterica Strains from Informal Markets in Cambodia.

Salmonella enterica is an important global pathogen due to its contribution to human morbidity and death. The presence of S. enterica in Southeast Asian informal markets is amplified by cross-contamination between market surfaces and food products. Here, we describe the draft genome sequences of 81 Salmonella enterica isolates from informal markets in Cambodia.

Evaluation of marbling and enhancement's abilities to compensate for reduced beef palatability at elevated degrees of doneness.

The objectives of this study were to evaluate the extent marbling compensates for reduced beef palatability at elevated degrees of doneness and to determine the relationship of residual moisture and fat in cooked steaks to beef palatability, specifically beef juiciness. Paired strip loins (IMPS # 180) were collected to equally represent five quality treatments [Prime, Top Choice (modest and moderate marbling), Low Choice, Select, and Select Enhanced (110% of raw weight)]. Steaks were grouped into sets of three consecutively cut steaks and randomly assigned a degree of doneness (DOD): very-rare (VR; 55 °C), rare (R; 60 °C), medium-rare (MR; 63 °C), medium (M; 71 °C), well done (WD; 77 °C), or very well done (VWD; 82 °C). Samples were subjected to consumer and trained sensory evaluation, Warner-Braztler shear force (WBSF), slice shear force (SSF), pressed juice percentage (PJP) evaluation, and raw and cooked proximate analysis. There were no (P > 0.05) quality treatment × DOD interactions for consumer sensory ratings, indicating increased DOD had the same negative impact regardless of marbling level. There was a quality treatment × DOD interaction (P < 0.05) for the percentage of steaks rated acceptable by consumers for juiciness. Increased marbling modified the point in which steaks became unacceptable for juiciness. Similarly, there was a quality treatment × DOD interaction (P < 0.05) for trained juiciness ratings. When cooked to MR and lower, Prime was rated only 8% to 18% higher (P < 0.05) than Select for trained juiciness ratings, but was rated 38% to 123% higher (P < 0.05) than Select when cooked to M and higher. Besides cooking loss, combined cooked moisture and fat percentage was more highly associated (P < 0.01) to consumer juiciness (r = 0.69) and trained initial (r = 0.84) and sustained (r = 0.85) juiciness ratings than all other objective evaluations. Using regression analyses, cooked moisture and fat percentages, alone, were poor indicators of consumer and trained juiciness ratings. However, when combined, the regression equations explained 45%, 74%, and 69% of the variation in consumer, trained initial, and trained sustained juiciness ratings, respectively. These results indicate that increased marbling levels only offer "insurance" for juiciness of steaks that are cooked to high degrees of doneness, but not for other palatability traits. Additionally, cooked residual moisture and fat percentages, when combined, are a good indicator of sensory juiciness ratings.

Salmonella and Campylobacter baseline in retail ground beef and whole-muscle cuts purchased during 2010 in the United States.

Salmonella enterica and Campylobacter spp. cause a considerable number of human illnesses each year, and the vast majority of cases are foodborne. The purpose of this study was to establish the baseline of Salmonella and Campylobacter in beef products purchased from U.S. retail markets. Sampling was carried out in 38 American cities. Retail raw ground and whole-muscle beef (n = 2,885) samples were purchased and examined for the presence of Salmonella. Samples testing positive for Salmonella were identified with the commercial BAX System, which is a real-time PCR-based system. Of the original samples purchased, 1,185 were selected and tested for the presence of Campylobacter. Positive samples were isolated via direct plating and confirmed via agglutination and biochemical testing. Salmonella was detected in 0.66% of the total samples purchased. The prevalence of Salmonella in ground beef packages was 0.42% for modified atmosphere packaging, 0.63% for chub packaging, and 0.59% for overwrapped packages. Salmonella was detected in 1.02% of whole-muscle cuts. There was no relationship (P = 0.18) between product type (ground or whole muscle) and the percentage of positive samples. Campylobacter was recovered from 9.3% of samples. A greater percentage (17.24%, P < 0.01) of whole-muscle cuts tested positive for Campylobacter compared with ground beef samples (7.35%). Estimating pathogen baselines in U.S. retail beef is essential for allotting resources and directing interventions for pathogen control. These data can be utilized for a more complete understanding of these pathogens and their impact on public health from the consumption of beef products.