Assessment of Staphylococcus aureus along milk value chain and its public health importance in Sebeta, central Oromia, Ethiopia

Prevalence, Cross Contamination, Virulence, and Multidrug Resistance Profiles of Staphylococcus aureus Isolates from Four Middle-Scale Dairy Farms in Bareilly, Northern India

Milk, a nutritious global important food commodity, serves as an excellent medium for microbial growth as well. The foodborne pathogen Staphylococcus aureus is a commensal member of human microflora that enters the food chain through poor hygienic practices and cross contamination and causes various clinical manifestations in humans. During this study, raw milk and swab samples (milker's hand, udder, towel, milking bucket, and farm floor) were collected from four middle-scale buffalo dairy farms. The results revealed S. aureus presence in 11.6% (n = 56/448) bucket raw milk samples and 2.6% (n = 12/448) udder raw milk samples. Contrarily, S. aureus prevalence was significantly higher in farm floors (100%, n = 84/84), towel (35.7%, n = 10/28), milking bucket (11.6%, n = 56/448), milker's hand (10.7%, n = 3/28), and udder swab samples (4.0%, n = 18/448). The chi-square test yielded p values of 0.000, 0.005, and 0.0011 for udder raw milk, udder swab, and milker's hand swab, respectively. The p values of the milking bucket (p = 0.048) and farm floors (p = 0.0183) confirmed their possible role in S. aureus cross contamination. Gene amplifications of nuclease and enterotoxin A indicate potential virulence of S. aureus isolates in collected samples. Antibiotic susceptibility testing revealed multidrug resistance in 44% (n = 239) of S. aureus isolates with the highest resistance of 61% against penicillin. Resistance against ampicillin, streptomycin, and lincomycin was observed. Fewer S. aureus isolates were resistant to kanamycin and erythromycin, whereas the lowest number of resistant isolates was observed against chloramphenicol. A high prevalence of S. aureus in the farm environment and milking equipment suggested the cross contamination of potentially enterotoxin-producing and multidrug-resistant S. aureus to raw milk. Therefore, good hygiene practices should be enforced to avoid foodborne and zoonotic infections.

Occurrence, multidrug resistance and potential risk factors for Staphylococcus aureus infection at worker-animal and working equipment interfaces: a systematic review and meta-analysis of the Ethiopian literature

Background

Staphylococcus aureus (S. aureus) infecting animals and humans via close contact, handling, or consuming contaminated products is a growing public health concern. In Ethiopia, it is important to examine the overall prevalence of S. aureus, patterns of multidrug resistance, and potential risks in human-animal interface settings. Thus, this review was conducted to estimate the pooled prevalence of S. aureus, its multidrug resistance, and potential risk factors for worker-animal-working equipment interactions.

Methods

This systematic review and meta-analysis were carried out by the PRISMA guidelines. The research articles were searched from PubMed, HINARI, Web of Sciences, and Google Scholar databases.

Results

This meta-analysis included 13 independent articles and 52 dependent studies. In total, 5,329 humans, 5,475 animals, and 5,119 samples of working equipment were analyzed. The pooled prevalence of S. aureus at the interfaces between humans, animals, and working equipment was 22%, there was a high level of heterogeneity (I2 = 94%: p < 0.01). The overall pooled prevalence of S. aureus in dairy farm sources was 23% (95% CI, 17-30%) compared to 18% in abattoirs. The pooled prevalence of S. aureus was estimated to be 25% for human sources, 23% for animal sources, and 19% for working equipment. The total multidrug resistance (MDR) rate was 27%. The present study illustrates that a predominant antimicrobials comprising ampicillin, penicillin, chloramphenicol, tetracycline, and ciprofloxacin, accounts for the development of resistance in S. aureus strains, with a prevalence of 72%. According to the qualitative assessment of potential risk factors, animal age, worker education, lactation stage, and hand washing by milkers influenced the circulation of S. aureus at animal-worker and working equipment interfaces.

Conclusion

The pooled prevalence of S. aureus at the interface of human,-and animal-working equipment was quantified at 22%. S. aureus was found in humans, animals, and equipment at nearly the same rate. The results of this study demonstrate that S. aureus is hazardous and circulates among animals, workers, and equipment: farmers, animal owners, employees, and the public need to be educated about S. aureus. Moreover, animals and work equipment should be included in the control and prevention of S. aureus infection.

Identification and antimicrobial susceptibility profiles of Staphylococcus species isolated from raw cow milk, and swabs in smallholder dairy farms in Meta district, Eastern Ethiopia

BACKGROUND

The safety of milk production in terms of foodborne infections is a worldwide issue, particularly in developing countries where production is often unhygienic. A cross-sectional study was conducted from December 2018 to August 2019 in the Meta District of Eastern Hararghe Zone, Oromia Regional State, Ethiopia. We aim to assess milk hygiene practices among smallholder dairy farmers, estimate the prevalence of Staphylococcus aureus in raw cow milk and swabs, assess associated risk factors, and the antimicrobial susceptibility test of S. aureus isolates. Face-to-face interviews with 30 respondents randomly selected from smallholder dairy farmers were used to assess the potential risk factors for S. aureus contaminations in milk. A total of 177 samples were examined using standard microbiological testing. The disc diffusion technique was also employed to assess the antibiotic susceptibility of the isolates. The data was analyzed using STATA® version 14.0 statistical software.

RESULTS

According to the milk hygiene assessment, 80% of respondents did not wash cow udder before milking, did not use detergent to clean milk containers, and did not keep milk refrigerated before consumption or sale, while 63.3% of milk consumers ingested raw milk. They had never heard of staphylococci foodborne disease. Likewise, the overall prevalence of S. aureus was 12.42% (95%CI: 8.32-18.98). The prevalence of S. aureus in udder milk, equipment swabs, and milkers' hands was 18.8%, 26.7%, and 30%, respectively. The prevalence of S. aureus in milk is significantly associated with age, and mastitis history (p < 0.05). Moreover, old and mastitis positive animals were eight (OR: 8.40; 95%CI: 1.68-41.89) and four (OR: 4.33; 95%CI: 1.37-13.66) times more likely to be infected by S. aureus than adult, and mastitis negative animal. The isolates were resistant to penicillin G (97.4%) and tetracycline (69.2%) whereas susceptible to kanamycin, streptomycin, vancomycin, and cefotaxime, at 84.6%, 71.8%, 64%, and 58.8%, respectively.

CONCLUSION

This study revealed the presence of antimicrobial-resistant patterns of S. aureus on commonly used antibiotics, as well as inadequate milk handling practices in the study area. Thus, awareness should be created on proper milk handling and hygiene as well as appropriate uses of antibiotics should be encouraged.

Isolation and antimicrobial resistance patterns of Methicillin-resistantStaphylococcus aureus from raw cow's milk in dairy farms of Wolaita Sodo Town, Southwest, Ethiopia

Staphylococcus aureus is a pathogenic bacterium-contaminating milk and milk products causing food poisoning primarily due to its enterotoxins. A cross-sectional study was conducted from November 2021 to June 2022 in Wolaita Sodo Town, to detect Methicillin-resistant Staphylococcus aureus (MRSA) in raw cow's milk and assess their resistance levels to different antimicrobials. Purposive sampling was used to select 34 dairy farms. Accordingly, 419 raw milk samples from the farm and collection centers were collected. Isolates of S. aureus showing resistance to Cefoxitin were classified as MRSA. From the total 419 samples, 22.19% (93/419) were contaminated with S. aureus in dairy cows. The prevalence of S. aureus in raw milk, bulk milk from the farm, and bulk tank milk from the collection centers was 16.9%, 2.1%, and 3.1%, respectively. The risk of S. aureus contamination in dairy farm owners and milkers who do not take food safety training was 5.303 times higher than the risk of S. aureus contamination in dairy farm owners and milkers who take food safety training. The risk of S. aureus contamination in dairy farms kept under poor management system was 7.34 times more than that of dairy farms kept under good management. The cefoxitin disk diffusion method was used to detect MRSA, 57.14% being resistant to Cefoxitin in total while approximately 87.5% were sensitive to Sulfamethoxazole-trimethoprim and Gentamycin, while Erythromycin registered 75%, Ciprofloxacin 62.5%, Chloramphenicol 62.5%, and Tetracycline 25%. This study revealed that MRSA exhibited a notable multidrug resistance pattern, encompassing resistance to multiple drugs, with a prevalence of 75%. Significantly, the hands of milkers and the milking containers emerged as pivotal sources of contamination. This underscores the crucial importance of maintaining stringent hygienic practices during the milking process, with particular emphasis on thorough cleaning and decontamination of utensils.

Occurrence, antimicrobial susceptibility, and resistance genes of Staphylococcus aureus in milk and milk products in the Arsi highlands of Ethiopia

BACKGROUND

In Ethiopia, milk production and handling practices often lack proper hygiene measures, leading to the potential contamination of milk and milk products with Staphylococcus aureus (S. aureus), including methicillin-resistant strains, posing significant public health concerns. This study aimed to investigate the occurrence, antimicrobial susceptibility profiles and presence of resistance genes in S. aureus strains isolated from milk and milk products.

METHODS

A cross-sectional study was conducted in the Arsi highlands, Oromia, Ethiopia from March 2022 to February 2023. A total of 503 milk and milk product samples were collected, comprising 259 raw milk, 219 cottage cheese, and 25 traditional yogurt samples. S. aureus isolation and coagulase-positive staphylococci enumeration were performed using Baird-Parker agar supplemented with tellurite and egg yolk. S. aureus was further characterized based on colony morphology, Gram stain, mannitol fermentation, catalase test, and coagulase test. Phenotypic antimicrobial resistance was assessed using the Kirby-Bauer disc diffusion method, while the polymerase chain reaction (PCR) was employed for confirming the presence of S. aureus and detecting antimicrobial resistance genes.

RESULTS

S. aureus was detected in 24.9% of the milk and milk products, with the highest occurrence in raw milk (40.9%), followed by yogurt (20%), and cottage cheese (6.4%). The geometric mean for coagulase-positive staphylococci counts in raw milk, yogurt, and cottage cheese was 4.6, 3.8, and 3.2 log10 CFU/mL, respectively. Antimicrobial resistance analysis revealed high levels of resistance to ampicillin (89.7%) and penicillin G (87.2%), with 71.8% of the isolates demonstrating multidrug resistance. Of the 16 S. aureus isolates analyzed using PCR, all were found to carry the nuc gene, with the mecA and blaZ genes detected in 50% of these isolates each.

CONCLUSION

This study revealed the widespread distribution of S. aureus in milk and milk products in the Arsi highlands of Ethiopia. The isolates displayed high resistance to ampicillin and penicillin, with a concerning level of multidrug resistance. The detection of the mecA and blaZ genes in selected isolates is of particular concern, highlighting a potential public health hazard and posing a challenge to effective antimicrobial treatment. These findings highlight the urgent need to enhance hygiene standards in milk and milk product handling and promote the rational use of antimicrobial drugs. Provision of adequate training for all individuals involved in the dairy sector can help minimize contamination. These measures are crucial in addressing the threats posed by S. aureus, including methicillin-resistant strains, and ensuring the safety of milk and its products for consumers.

Zoonotic tuberculosis in a high bovine tuberculosis burden area of Ethiopia

Background

Tuberculosis (TB) is a major cause of ill health and one of the leading causes of death worldwide, caused by species of the Mycobacterium tuberculosis complex (MTBC), with Mycobacterium tuberculosis being the dominant pathogen in humans and Mycobacterium bovis in cattle. Zoonotic transmission of TB (zTB) to humans is frequent particularly where TB prevalence is high in cattle. In this study, we explored the prevalence of zTB in central Ethiopia, an area highly affected by bovine TB (bTB) in cattle.

Method

A convenient sample of 385 patients with pulmonary tuberculosis (PTB, N = 287) and tuberculous lymphadenitis (TBLN, N = 98) were included in this cross-sectional study in central Ethiopia. Sputum and fine needle aspirate (FNA) samples were obtained from patients with PTB and TBLN, respectively, and cultures were performed using BACTEC™ MGIT™ 960. All culture positive samples were subjected to quantitative PCR (qPCR) assays, targeting IS1081, RD9 and RD4 genomic regions for detection of MTBC, M. tuberculosis and M. bovis, respectively.

Results

Two hundred and fifty-five out of 385 sampled patients were culture positive and all were isolates identified as MTBC by being positive for the IS1081 assay. Among them, 249 (97.6%) samples had also a positive RD9 result (intact RD9 locus) and were consequently classified as M. tuberculosis. The remaining six (2.4%) isolates were RD4 deficient and thereby classified as M. bovis. Five out of these six M. bovis strains originated from PTB patients whereas one was isolated from a TBLN patient. Occupational risk and the widespread consumption of raw animal products were identified as potential sources of M. bovis infection in humans, and the isolation of M. bovis from PTB patients suggests the possibility of human-to-human transmission, particularly in patients with no known contact history with animals.

Conclusion

The detected proportion of culture positive cases of 2.4% being M. bovis from this region was higher zTB rate than previously reported for the general population of Ethiopia. Patients with M. bovis infection are more likely to get less efficient TB treatment because M. bovis is inherently resistant to pyrazinamide. MTBC species identification should be performed where M. bovis is common in cattle, especially in patients who have a history of recurrence or treatment failure.

Pathogenic Bacteria and Their Antibiotic Resistance Patterns in Milk, Yoghurt and Milk Contact Surfaces in Debre Berhan Town, Ethiopia

Background

Bacterial contamination of milk is a primary culprit for causing foodborne illnesses, presenting a significant health hazard for millions of individuals around the globe. The level and variety of microorganisms present in raw milk determine its degree of contamination and the potential health risks it poses.

Methods

A cross-sectional survey was conducted from February to August. A questionnaire was used to collect data on socio-demographic characteristics and hygiene practices from milk distributors and traders. Raw milk, yoghurt, swabs from milk containers and drinking cups were collected and processed for bacterial isolation and identification, antibiotic susceptibility testing, MDR screening and confirmation, ESBL screening and confirmation. Finally, all data were pooled and analyzed using SPSS software version 25.

Results

A total of 120 samples of fresh milk, yogurt and cotton swabs from milk containers and cups were collected. A total of 80 bacterial isolates were isolated from 120 samples. Among the bacteria isolated, S. aureus 17 (21.3%), E. coli 17 (21.3%), S. epidermidis 14 (17.5%), Klebsiella spp. 9 (11.3%) and Salmonella spp. 7 (8.8%) were detected most often. High rate of contamination was observed in fresh milk 23 (28.8%) and yogurt 23 (28.8%). All isolates were resistant to at least one antibiotic tested. Comparatively, high rates of resistance were observed in all isolates to the most commonly prescribed antibiotics in Ethiopia. However, lower rates of resistance have been observed for recently introduced antibiotics in Ethiopia. Of the isolates, 20 (25.0%) were resistant to eight or more antibiotics. While 16 (20.0%), 12 (15.0%), 9 (11.3%) isolates were resistant to two, three and five antibiotics, respectively. Of the bacteria isolated, 52/80 (65.0%) were MDR, 25/49 (51.0%) were screened for ESBL production, and 20/49 (40.8%) isolates were confirmed as ESBL producer.

Conclusion

This study showed a high rate of bacterial isolates along with MDR and ESBL-producing strains in raw milk, yoghurt, milk container swabs and drinking cup swab samples, associated with poor hygiene and sanitation practices.

Factors affecting the microbiological quality and contamination of farm bulk milk by Staphylococcus aureus in dairy farms in Asella, Ethiopia

BACKGROUND

The determination of the microbiological quality and safety of raw milk and the associated influencing factors at the farm level is very critical given that the quality or safety of subsequent products that are further produced depends on this. Therefore, this study aimed to determine the microbiological quality and safety of bulk milk and identify associated risk factors, and assess the presence/absence of S. aureus in bulk milk with potential contaminating sources in dairy farms in Asella, Ethiopia.

RESULTS

The geometric means of bacterial counts in farm bulk milk were 5.25 log cfu/ml, 3.1 log cfu/ml and 2.97 log cfu/ml for total bacterial count (TBC), coliform count (CC) and coagulase-positive staphylococci count (CPS), respectively. Of the 50 dairy farms, 66, 88, and 32% had TBC, CC and CPS counts, respectively, that exceeded the standard international limits for raw cow's milk intended for direct human consumption. TBC tended to increase as CC increased in bulk milk (r = 0.5). In the final regression model, increased TBC, CC and the contamination of farm bulk milk by S. aureus were significantly associated with dirty barns, dirty cows and soiled udder and teats. TBC was higher during the rainy season than during the dry season. The reported practice of washing teats with warm water significantly decreased CC and CPS. The occurrence of S. aureus was significantly (p < 0.05) higher in bulk farm milk (42%) than in pooled udder milk (37.3%), teat swabs (22.5%), milkers' hand swabs (18%), bulking bucket swabs (16.7%), milking container swabs (14%), and water for cleaning of udder and milkers' hands (10%). The questionnaire survey result showed widespred raw milk consumption habits, low level of training and poor hygienic milking practices.

CONCLUSIONS

This study revealed low-quality bulk farm milk with high bacterial counts and a high occurrence of S. aureus. This indicates the potential food safety risks due to consumption of raw milk or its products. This study suggests awareness creation to dairy farmers and the public on hygienic milk production and heat treatment of milk before consumption.

Foodborne disease hazards and burden in Ethiopia: A systematic literature review, 1990–2019

Background

Foodborne disease (FBD) affects millions of people each year, posing a health burden similar to malaria, tuberculosis or HIV. A recent World Bank study estimated the productivity losses alone attributed to unsafe food within Africa at $20 billion in 2016, and the cost of treating these illnesses at an additional $3.5 billion. Ethiopia faces multiple food safety challenges due to lack of infrastructure and basic pre-requisites for food safety such as clean water and environment, washing facilities, compounded by limited implementation of food safety regulations, and a lack of incentives for producers to improve food safety. A consolidation of our understanding and evidence of the source, nature and scale of FBD in Ethiopia is needed to inform policy and future research. We performed a Systematic Literature Review (SLR) of publications on FBD occurrence in Ethiopia including hazard presence and impact.

Method

The SLR followed Cochrane and PRISMA guidelines. We searched PubMed and CAB-Direct for relevant publications between 1990 and 2019 (inclusive). Observational studies and reviews were included. Two reviewers screened titles and abstracts, and retained publications were reviewed in full for quality and data extraction.

Result

In total 128 articles met the inclusion criteria. Most articles focused on the identification of biological hazards in food. High levels of microbial contamination in different food value chains were often found in the small, ad hoc, observational studies that dominated the literature. Raw milk (22/128, 17.0%) and raw beef (21/128, 16.4%) were the most studied food products. Foodborne (FB) parasites were often found at higher rates in food than bacterial and viral pathogens, possibly due to differences in ease of identification. High levels of bacterial contamination on the hands of food handlers were widely reported. There were no reports on the incidence of human FBDs or resulting health and economic impacts.

Conclusion

Our findings reflect existing concerns around food safety in Ethiopia. A lack of substantial, coordinated studies with robust methodologies means fundamental gaps remain in our knowledge of FBD in Ethiopia, particularly regarding FBD burden and impact. Greater investment in food safety is needed, with enhanced and coordinated research and interventions.

Swarming Magnetic Microrobots for Pathogen Isolation from Milk

Bovine mastitis produced by Staphylococcus aureus (S. aureus) causes major problems in milk production due to the staphylococcal enterotoxins produced by this bacterium. These enterotoxins are stable and cannot be eradicated easily by common hygienic procedures once they are formed in dairy products. Here, magnetic microrobots (MagRobots) are developed based on paramagnetic hybrid microstructures loaded with IgG from rabbit serum that can bind and isolate S. aureus from milk in a concentration of 3.42 10⁴ CFU g^-1 (allowable minimum level established by the United States Food and Drug Administration, FDA). Protein A, which is present on the cell wall of S. aureus, selectively binds IgG from rabbit serum and loads the bacteria onto the surface of the MagRobots. The selective isolation of S. aureus is confirmed using a mixed suspension of S. aureus and Escherichia coli (E. coli). Moreover, this fuel-free system based on magnetic robots does not affect the natural milk microbiota or add any toxic compound resulting from fuel catalysis. This system can be used to isolate and transport efficiently S. aureus and discriminate it from nontarget bacteria for subsequent identification. Finally, this system can be scaled up for industrial use in food production.

Staphylococcus aureus in cow milk and milk products in Ambo and Bako towns, Oromia, Ethiopia: prevalence, associated risk factors, hygienic quality, and antibiogram

BACKGROUND

Staphylococcus aureus (S. aureus) is a foodborne bacterial pathogens that can cause staphylococcal food poisoning and contaminate food of animal origin worldwide. The current study was conducted to estimate the prevalence and assess risk factors, hygienic quality, and antibiogram of S. aureus in raw milk and milk products of cows in Ambo and Bako towns, Ethiopia.

RESULTS

The overall prevalence of S. aureus in milk and milk products was 15.6% (94/601) with the highest prevalence in bulk tank raw milk (17.50%) and the lowest in "Ergo" (13.11%). High S. aureus contamination at farm level were associated with poor farm hygiene, extensive management system, medium farm size, loose housing, and less frequent removal of bedding. At the cow level, a high S. aureus isolation rate was observed in crossbred cows; cows with age equal to or greater than 5 years old, tick infestation, history of mastitis treatment, and udder washing were not practiced before milking. On the other hand, the type of container, hygiene of milk handler, and container were the major risk factors for bulk tank milk contamination with S. aureus. S. aureus counts ranging from 1.25 × 10⁴ to 1.92 × 10⁴ CFU/mL were detected in 28.33% of the bulk tank milk samples.. Antimicrobial susceptibility test showed higher resistance of S. aureus to amoxicillin (98.48%), oxacillin (98.48%), ampicillin (98.48%), cefoxitin (92.42%), and tetracycline (83.33%), with 43.94% of isolates showing multidrug resistance (MDR). The high prevalence of oxacillin and cefoxitin-resistant isolates, which is a possible indicator of the existence of methicillin-resistant Staphylococcus aureus (MRSA), was also noted in the current study.

CONCLUSION

Higher prevalence of S. aureus and MDR isolates in milk and milk products was detected in study areas. Therefore, to make milk and milk products safe for human consumption, hygienic handling of milk and milk products, regular surveillance of antimicrobial resistance, and prudent use of drugs are recommended.

Prevalence, Contamination Level, and Associated Factors of Methicillin-Resistant Staphylococcus aureus in Raw Cow Milk at Selected Districts of Gamo Zone, Southern Ethiopia

Staphylococcus aureus is pathogenic bacterium contaminating milk and milk products causing bacterial food poisoning. In the current study sites, there is no information on methicillin-resistant Staphylococcus aureus. Thus, the current study sought to assess the risk factors that contribute to the contamination of raw cow milk, the bacterial load, and the prevalence of methicillin-resistant Staphylococcus aurous. A cross-sectional study was conducted, January to December, 2021, on randomly selected 140 milk samples from selling point of Arba Minch Zuria and Chencha districts. Fresh milk samples were processed and tested for bacterial load, bacterial isolation, and methicillin susceptibility patterns. Questionnaire survey was conducted on 140 producers and collectors to assess hygienic factors attributed to contamination of raw cow milk with Staphylococcus aureus. The overall prevalence of S. aureus was 42.1% (59/140) (95% confidence interval (CI): 34.80-51.40%). About 15.6% (22/140) of the milk samples assessed had the viable count and total S. aureus count higher than 5log cfu/mL with 5.3 + 1.68 and 1.36 + 1.7log cfu/ml^-1 bacterial loads, respectively. The rate of isolation of S. aureus was significantly high in milk from highland than lowland (p=0.030). The multivariable logistic regression revealed that educational status (OR: 6.00; 95% CI: 4.01-8.07), picking one's nose while working on milk (OR: 1.41; 95% CI: 0.54-2.25), cleaning the milk can (OR: 4.5; 95% CI: 2.61-5.17), hand washing activities (OR: 3.4; 95% CI: 1.670-6.987), check for abnormal milk (OR: 2; 95% CI: 1.55-2.75), and container for milk (OR: 3; 95% CI: 0.12-0.67) were risk factors significantly associated with the occurrence of S. aureus in milk. In conclusion, the highest rate of resistance was observed to ampicillin (84.7%) and cefoxitin (76.3%). All isolates are resistant to at least two types of antimicrobial drugs, while 65.0% of the isolates were found to be multidrug-resistant. The higher prevalence, high load, and antimicrobial resistance of S. aureus indicate the higher public health risk due to the widespread consumption of raw milk in the area. Furthermore, consumers in the study area should be aware of the risks associated with consuming raw milk.

Occurrence and antimicrobial susceptibility of Staphylococcus aureus in dairy farms and personnel in selected towns of West Shewa Zone, Oromia, Ethiopia

Staphylococcus aureus is one of the foodborne disease-causing bacterial pathogens. A cross-sectional study was conducted in selected towns of the West Shewa Zone, Oromia, Ethiopia from December 2020 to April 2021. The objectives of the study were to estimate the occurrence and load of S. aureus in raw cows' milk, the antimicrobial susceptibility patterns of the S. aureus isolates, and assess the knowledge, attitude, and practice of the farmers on factors of antimicrobial resistance. A total of 311 samples from raw cows' milk (212), milkers' hands (44), and milking buckets (55) swabs were collected and tested. The disc diffusion method was used to test the antimicrobial susceptibility of the isolates. A questionnaire survey was conducted to assess the factors of milk contamination with S. aureus and antimicrobial resistance. The Chi-square test, one-way analysis of variance, and logistic regression analysis were used for data analyses. The result indicated that 16.72% (52/311) (95% CI: 12.75-21.34%) of the samples were positive for S. aureus. The occurrence of S. aureus was 22.73%, 16.51%, and 12.73% in milkers' hand swabs, cow milk, and milking bucket swabs, respectively. The mean count of S. aureus from raw cows' milk was 4.3± 1.45 log10 CFU/ml. About 88% of S aureus isolates were resistant to ampicillin while 82.9% and 70.7% of the isolates were susceptible to ciprofloxacin and cefotaxime respectively. The majority of the S. aureus isolates (61%) showed multi-drug resistance. The odds of S. aureus isolation from the milk of cows were significantly high in older cows (Adjusted Odds Ratio [AOR]: 5.54; p = 0.001), in late lactation stages (AOR: 3.6; p = 0.012), and in farms where house cleaning was done twice per week (AOR: 8.7; p = 0.001). A high percentage of farmers had insufficient knowledge, attitude, and practice (KAP) about the factors contributing to antimicrobial resistance. In conclusion, the poor milk hygienic practices, high rate of antimicrobial resistance (AMR), and inadequate KAP of farmers about factors of AMR suggest potential public health risks thus requiring training and surveillance programs.

Raw cow milk nutritional content and microbiological quality predictors of South Gondar zone dairy farmers in Ethiopia, 2020

Background

Raw milk is a good growth medium for microbes because of its neutral pH and nutrient content. In Ethiopia; few studies were done to assess the microbial quality of raw cow milk. But, none of them focused on the nutrient content of raw cow milk. Therefore; this study aimed at evaluating raw cow milk nutrient content and predictors of microbial quality of raw cow milk among milk in the dairy farmers of South Gondar zone (SGZ), Ethiopia.

Methods

A community-based cross-sectional study was conducted from January to May 2020. 160 randomly selected raw cow milk, water, and utensil samples each were collected for microbial analysis. Besides, nutrient content indicators such as TotalSolid (TS), and Specific Gravity (SG) were analyzed from milk samples. Sequentially, The Knowledge, Attitude, and Practices (KAP) of millers were also assessed using a pretested structured questionnaire. Chi-square test and multiple linear regression models were used.

Results

The overall mean SG and TS of raw cow milk were 1.027 (95% CI, 1.013-1.039) and 12.55% (95%CI, 12.20%-12.89%) respectively.38.13% had the better nutrient content, and the rest, 61.87% of raw cow milk hadn't the better nutrient content. Besides, the mean (SD) in log CFU/100mL-1of the Escherichia coli count of raw cow milk was 15 (0.3). Educational status, milk handling experience, KAP of milkers, water microbial count, Nutrient content, and microbial load of milk utensils were independently predicted microbial quality of raw cow milk.

Conclusions and implications

The result signifies that the raw cow milk hadn't better nutrient content and the educational status and KAP of milkers, and the qualities of water were the major factors affecting the microbial quality of raw cow milk. It could greatly affect the Food and Nutrition Security of the country. Hence, measures should be taken to enhance the KAP of milkers for improving this enteropathy.

Genomic analysis, antibiotic resistance, and virulence of Staphylococcus aureus from food and food outbreaks: A potential public concern

Transmission and outbreaks of Staphylococcus aureus among retail food highlights the need to comprehensive analysis the molecular characteristic of Staphylococcus aureus in foods. However, the information about Staphylococcus aureus in north China is limited. In this study, 97 and 28 S. aureus strains were isolated for analysis from 4262 samples of retail food and 61 samples food outbreaks with prevalence rate 2.28 % and 45.9 %, respectively in Jilin, China from 2014 to 2018. This study aimed to investigate the prevalence of S. aureus isolates and characterize by antimicrobial resistance testing, virulence profiles, spa typing, and multilocus sequence typing (MLST) analysis. 60 % (75/125) of the isolates contained at least enterotoxin genes including classic and new SEs genes as following: sea (40/125,32 %), see (36/125,28.8 %), sec (29/125,23.2 %), sell (29/125,23.2 %), seb (25/125,20 %), seh (22/125,17.6 %), sed (6/125,4.8 %), selq (6/125,4.8 %), and selk (6/125,4.8 %). In antimicrobial susceptibility tests, 59.2 % of the isolates (74/125) were considered as multi-drug-resistant isolates and four MRSA strains were all found with high multi-drug-resistance. Phenotype resistance to penicillin (94.4 %), erythromycin (84.2 %), clindamycin (63.9 %), and tetracycline (47.2 %) was observed which was corresponding with genotype resistance. The strains were classified to twenty-two sequence types (STs), fourteen clonal complexes (CCs), and forty-seven spa types. The predominant ST and spa types were ST1(22/125,17.6 %), ST25(20/125,16.00 %), ST398 (14/125,11.2 %) and t127 (20/125,16 %), t078 (14/125,11.2 %), t803 (7/125,5.6 %). The wgSNP analysis of these isolates in food represents showed close relatedness with food outbreaks which pose a potential health risk for consumers and warrants further attention.

Detection of mecA gene and methicillin-resistant Staphylococcus aureus (MRSA) isolated from milk and risk factors from farms in Probolinggo, Indonesia

Background: Staphylococcus aureus is commonly found in dairy cows and is a source of contamination in milk. S. aureus that are resistant to beta-lactam antibiotics (especially cefoxitin) are referred to as methicillin-resistant Staphylococcus aureus (MRSA).  The spread of MRSA cannot be separated from sanitation management during milking; it can originate from milk collected from the udder or from the hands of farmers during the milking process. The purpose of this study was to examine the level of MRSA contamination in dairy cow's milk and farmer's hand. Methods: A total of 109 samples of dairy cow's milk and 41 samples of farmer's hand swabs were collected at a dairy farm in Probolinggo, East Java, Indonesia. Samples were cultured and purified using mannitol salt agar (MSA). The profile of S. aureus resistance was established by disk diffusion test using a disk of beta-lactam antibiotics, namely oxacillin and cefoxitin. Results: The S. aureus isolates that were resistant to oxacillin and cefoxitin antibiotics were then tested for oxacillin resistance screening agar base (ORSAB) as a confirmation test for MRSA identity. S. aureus isolates suspected to be MRSA were then tested genotypically by polymerase chain reaction (PCR) method to detect the presence of the mecA gene. The results of the isolation and identification found 80 isolates (53.33%) of S. aureus. The results of the resistance test found that 42 isolates (15%) of S. aureus were resistant to oxacillin and 10 isolates (12.5%) were resistant to cefoxitin. The ORSAB test found as many as 20 isolates (47.62%) were positive for MRSA. In PCR testing to detect the presence of the mecA gene, three isolates (30%) were positive for the mecA gene. Conclusions: This study shows that several S. aureus isolates were MRSA and had the gene encoding mecA in dairy farms.

Detection of mecA gene and methicillin-resistant Staphylococcus aureus (MRSA) isolated from milk and risk factors from farms in Probolinggo, Indonesia

Background: Staphylococcus aureus is commonly found in dairy cows and is a source of contamination in milk. S. aureus that are resistant to beta-lactam antibiotics (especially cefoxitin) are referred to as methicillin-resistant Staphylococcus aureus (MRSA). The spread of MRSA cannot be separated from sanitation management during milking; it can originate from milk collected from the udder or from the hands of farmers during the milking process. The purpose of this study was to examine the level of MRSA contamination in dairy cow's milk and farmer's hand. Methods: A total of 109 samples of dairy cow's milk and 41 samples of farmer's hand swabs were collected at a dairy farm in Probolinggo, East Java, Indonesia. Samples were cultured and purified using mannitol salt agar (MSA). The profile of S. aureus resistance was established by disk diffusion test using a disk of beta-lactam antibiotics, namely oxacillin and cefoxitin. Results: The S. aureus isolates that were resistant to oxacillin and cefoxitin antibiotics were then tested for oxacillin resistance screening agar base (ORSAB) as a confirmation test for MRSA identity. S. aureus isolates suspected to be MRSA were then tested genotypically by polymerase chain reaction (PCR) method to detect the presence of the mecA gene. The results of the isolation and identification found 80 isolates (53.33%) of S. aureus. The results of the resistance test found that 42 isolates (15%) of S. aureus were resistant to oxacillin and 10 isolates (12.5%) were resistant to cefoxitin. The ORSAB test found as many as 20 isolates (47.62%) were positive for MRSA. In PCR testing to detect the presence of the mecA gene, three isolates (30%) were positive for the mecA gene. Conclusions: This study shows that several S. aureus isolates were MRSA and had the gene encoding mecA in dairy farms.

Detection of mecA gene and methicillin-resistant Staphylococcus aureus (MRSA) isolated from milk and risk factors from farms in Probolinggo, Indonesia

Background: Staphylococcus aureus is commonly found in dairy cows and is a source of contamination in milk. S. aureus that are resistant to beta-lactam antibiotics are referred to as methicillin-resistant Staphylococcus aureus (MRSA). The spread of MRSA cannot be separated from sanitation management during milking; it can originate from milk collected from the udder or from the hands of farmers during the milking process. The purpose of this study was to examine the level of MRSA contamination in dairy cow's milk and farmer's hand swabs. Methods: A total of 109 samples of dairy cow's milk and 41 samples of farmers' hand swabs were collected at a dairy farm in Probolinggo, East Java, Indonesia. Samples were cultured and purified using mannitol salt agar (MSA). The profile of S. aureus resistance was established by disk diffusion test using a disk of beta-lactam antibiotics, namely oxacillin and cefoxitin. Results: The S. aureus isolates that were resistant to oxacillin and cefoxitin antibiotics were then tested for oxacillin resistance screening agar base (ORSAB) as a confirmation test for MRSA identity. S. aureus isolates suspected to be MRSA were then tested genotypically by polymerase chain reaction (PCR) method to detect the presence of the mecA gene. The results of the isolation and identification found 80 isolates (53.33%) of S. aureus. The results of the resistance test found that 42 isolates (15%) of S. aureus were resistant to oxacillin and 10 isolates (12.5%) were resistant to cefoxitin. The ORSAB test found as many as 20 isolates (47.62%) were positive for MRSA. In PCR testing to detect the presence of the mecA gene, three isolates (30%) were positive for the mecA gene. Conclusions: This study shows that several S. aureus isolates were MRSA and had the gene encoding mecA in dairy farms.

Detection and Determination of Staphylococcus aureus in Camel Milk and Associated Factors in Fedis, Eastern Hararghe, Ethiopia

Background

Camel milk is the key food for pastoralists in the arid and semi-arid areas of the eastern lowlands of Ethiopia. Unless it is handled under good hygienic conditions, milk can be a good medium for bacterial growth and can lead to foodborne diseases caused by various pathogenic microorganisms, such as Staphylococcus aureus. The current study was aimed to determine the prevalence of Staphylococcus aureus in raw camel milk and associated factors in Fedis, Eastern Ethiopia.

Methods

A cross-sectional study was conducted from December 2, 2018 to May 26, 2019 in Fedis, Eastern Hararghe, Ethiopia. The questionnaire was used to determine the hygienic practices of camel milkers and sellers. Laboratory analysis was conducted to determine the level of Staphylococcus aureus. A total of 156 (78 from households and 78 from selling sites) milk samples were collected randomly from selected camel herd owners and selling sites for the isolation and enumeration of Staphylococcus aureus. Data analysis was carried out using SPSS software version 22.0. Finally, Chi-square and Fisher's exact tests were used to analyze the data. A P-value of .05 was considered as the cut-off point for statistical significance.

Results

A total of 156 samples, including 78 samples of raw milk from the households and 78 samples from the market were purchased to determine Staphylococcus aureus. Out of 156 samples, Staphylococcus aureus was detected in 60 (38.5%) samples, of which 27 (34.6%) and 33 (42.3%) were among those collected from household and market, respectively. The overall mean Staphylococcus aureus count was 4.83 log CFU/mL, with household and market samples accounted for 2.76 and 5.08 log CFU/mL, respectively. Furthermore, 23 (38.3%) of the samples were contaminated with Staphylococcus aureus beyond the recommended level (4-5 log CFU/mL). There was a statistically significant association (P-value of <.05) between the prevalence of Staphylococcus aureus and other variables such as age of the camel, parity, lactation stages, and sources of milk.

Conclusion

More than one-third of milk samples were contaminated with Staphylococcus aureus at levels higher than the maximum permitted level. The findings of the current study suggests that there is a potential risk of foodborne infection and intoxication. Therefore, implementation of adequate hygiene and safety practices is very important to prevent the consumption of contaminated fruit juices, which leads to foodborne illness.

Isolation and Identification of Staphylococcus aureus from Milk and Milk Products, Associated Factors for Contamination, and Their Antibiogram in Holeta, Central Ethiopia

Staphylococcus aureus is a pathogenic bacterium-contaminating milk and milk products causing food poisoning primarily due to its enterotoxins. The study aimed at estimating the prevalence of S. aureus in milk and milk products, assessing potential risk factors for contamination, and determining the load and the antimicrobial susceptibility profile of the isolates. A cross-sectional study design was employed to collect a total of 486 samples, comprising 383 raw milk, 47 bulk tank milk, 29 curd milk (Ergo), and 28 Ethiopian cottage cheese (Ayib) samples. Enumeration, isolation, and identification of S. aureus were carried out following standard microbiological techniques. Antibiogram was performed using 12 antimicrobials following the Kirby–Bauer disc diffusion method. Logistic regression analyses were used to assess the association between the occurrence of S. aureus in milk and milk products and potential risk factors. The overall prevalence of S. aureus was 10.69% (52/486) [95% confidence interval (CI):8.09–13.79%]. The prevalence of S. aureus in raw milk, curd milk, bulk tanks at the farm, bulk tanks at milk collection facilities, and cottage cheese was 8.64%, 24.14%, 14.73%, 23.08%, and 14.29%, respectively. The rate of isolation of S. aureus was significantly high in curd milk than in other types of samples (P = 0.010). The study revealed that teat washing (OR: 4.93, 95% CI: 2.06–11.81), use of towel (OR: 12.13, 95% CI: 3.74–39.29), and tick infestations (OR: 4.31, 95% CI: 1.28–14.44) were risk factors associated with the occurrence of S. aureus in milk. About 48.39% of the milk samples assessed had the S. aureus count higher than 10⁵ CFU/ml. The highest rate of resistance was observed to ampicillin (95%), amoxicillin (95%), oxacillin (87.5%), and cefotaxime (80%). All isolates are resistant to at least two classes of antimicrobial drugs, while 65.0% of the isolates were found to be multidrug-resistant. The moderate prevalence, high load, and antimicrobial resistance of S. aureus indicate the higher public health risk due to the widespread consumption of raw milk in the area. Good hygienic practices, regular surveillance of antimicrobial resistance, and prudent use of drugs are suggested.

Milk and meat consumption patterns and the potential risk of zoonotic disease transmission among urban and peri-urban dairy farmers in Ethiopia

BACKGROUND

In the Ethiopian dairy farming system, prevalence of zoonotic diseases such as bovine tuberculosis (bTB) is high in the cattle population. This, combined with some risky milk and meat consumption habits, such as raw milk and uninspected raw meat consumption, poses a considerable risk of zoonotic disease transmission. A survey was conducted to investigate milk and meat consumption patterns, and the level of exposure to urban and peri-urban dairy-keeping households for risks of zoonotic disease transmission.

METHODS

Data on milk and meat consumption behaviours and other socioeconomic and demographic variables were collected from 480 urban and peri-urban dairy farms randomly surveyed in major towns in Ethiopia (Mekele, Hawassa, and Gondar towns, Addis Ababa city, as well as five Oromia towns around Addis Ababa). Determinants of raw milk consumption associated with a number of demographic and socio-economic factors were analysed using a generalised ordered logistic model.

RESULTS

The results indicated that about 20% the population consumed raw milk and their awareness about pasteurisation and its benefits were low. Location, gender of the household head, previous bTB testing of cattle on the farm, knowledge of zoonotic risks associated with raw milk consumption, household size, and per-capita milk consumption were found to be important determinants of the frequency of raw milk consumption. About 60% of the respondents were exposed to the risk of zoonotic diseases through their habit of frequently consuming raw meat. This was despite that over 90% of the respondents were aware of possible zoonotic risks of raw meat consumption. The determinants of raw meat consumption behaviours were associated with location, gender and age of the household head, household size, meat type preference, per-capita meat consumption, knowledge about disease transmission risks, and training on zoonoses.

CONCLUSION

Creating awareness about the risk factors for zoonotic transmission of diseases through training and media campaigns, improving meat hygiene through better abattoir services, and inducing behavioural change around meat sourcing, raw meat and raw milk consumption, are all crucial to the successful prevention and control of the spread of zoonotic diseases, including bTB.

Prevalence of Staphylococcus aureus, Methicillin-Resistant Staphylococcus aureus and Potential Risk Factors in Selected Dairy Farms at the Interface of Animal and Human in Bishoftu, Ethiopia

Background

Staphylococcus aureus (S. aureus) has been reported as the most commonly isolated highly contagious pathogen from human, animals and animal products. Methicillin-resistant Staphylococcus aureus (MRSA) has emerged as a significant pathogen with zoonotic potential that could have devastating consequence for the health and well-being of animals and human.

Methods

A cross-sectional study was conducted from July 2020 to January 2021. A total of 233 samples from cow milk, udder swabs and milkers' hand swabs were collected for culture and identification based on the standard protocol. Antimicrobial susceptibility tests were performed for all isolates by using Kirby Bauer's disk diffusion test. MRSA was detected by cefoxitin disk diffusion test.

Results

S. aureus was isolated from 50 (21.46%) of 233 samples and the prevalence of MRSA was 4%. The highest prevalence was found in cow milk 36 (25.53%) followed by hand swabs 10 (19.23%) and udder swabs 4 (10%). S. aureus prevalence was 58.33%, 30.0%, 21.43%, 17.92%, 15.79% in farm D, C, E, A, B respectively. A large percentage (58.33% and 30%) were from farm D and C. S. aureus isolation rate showed statistically significant association with farm types (p = 0.011) and with previous mastitis exposure (p = 0.001). High level of resistance was observed to penicillin (94%) and ampicillin (92%), but low level resistance to gentamicin (0%), amikacin (0%), ceftriaxone (0%), chloramphenicol (4%), ciprofloxacin and cefoxitin (4%). The overall prevalence of multidrug resistance (MDR) was 10.42%.

Conclusion

Prevalence of S. aureus in milk showed statistically significant association with respect to previous mastitis exposure and farm types (p = 0.011). High level of resistant to penicillin and ampicillin was observed. Therefore, effective mastitis control programs, best veterinary practice among all farms and use of antibiotics in the farm should be strictly controlled.

Prevalence and Antimicrobial Susceptibility Profile of Staphylococcus aureus in Milk and Traditionally Processed Dairy Products in Addis Ababa, Ethiopia

Staphylococcus aureus is a contagious pathogen that can cause various diseases in both humans and animals. Antimicrobial-resistant S. aureus is becoming an extremely important global health problem. A cross-sectional study was conducted from December 2019 to May 2020 to assess the occurrence of S. aureus and its antimicrobial susceptibility profiles in milk and traditionally processed dairy products in selected subcities of Addis Ababa. A total of 255 dairy product samples (175 raw milk and 80 traditionally processed dairy products) were collected from farms and retail markets. Samples were cultured for S. aureus according to standard microbiology techniques, and the Kirby-Bauer disk diffusion method was used to assess antimicrobial susceptibility of isolates to a panel of 12 antimicrobials. Susceptibility to methicillin was determined based on the sensitivity of isolates to cefoxitin, and resistant isolates were investigated for the presence of mecA and mecC genes using PCR. Staphylococcus aureus was isolated from 43 (24.6%) of milk, 7 (17.5%) of yogurt, and 2 (5%) of cottage cheese. A significantly higher rate of contamination with S. aureus was recorded among milk samples compared to yogurt and cottage cheese (p = 0.019). Out of 52 S. aureus isolates investigated for susceptibility to 12 antimicrobials, 49 (94.2%) of the isolates were resistant to ampicillin and 42 (80.8%) to amoxicillin+clavulanic acid. Twenty (38.5%) of the isolates were methicillin-resistant S. aureus (MRSA) based on susceptibility to cefoxitin. However, only one of these isolates (5%) was positive for mecA gene, and none of them were positive for the mecC gene. There was no significant difference (p > 0.05) in the rate of occurrence of MRSA among isolates from different sources. In conclusion, this study demonstrated a significant level of contamination of milk and dairy products with S. aureus and most isolates were multidrug resistant. The occurrence of MRSA in raw milk and dairy products signifies a serious public health threat as the practice of consuming raw dairy products in the study area is widespread. The lack of agreement between phenotypic and genotypic detection of MRSA suggests the need for further study to identify the genetic basis for the observed resistance phenotype.

Isolation and Characterization of Staphylococcus aureus From Food of Bovine Origin in Mekelle, Tigray, Ethiopia

Background:

Among Food-borne diseases, S. aureus is a leading cause of gastroenteritis resulting from the consumption of contaminated food.

Objectives:

The study aimed to isolate and characterize S. aureus from raw milk, yogurt and meat and determine its antibiotic sensitivity pattern.

Materials and Methods:

A cross-sectional study was conducted from December 2014 to June 2015 in Mekelle. A total of 284 samples were collected purposively. Enumeration of total viable bacteria count (TVBC), bacteriological isolation and identification, antimicrobial susceptibility testing, as well as PCR amplification of fem A and mec A genes were performed. Chi-square (χ2) and one way ANOVA tests were used for analysis.

Results:

Overall TVBC mean was found to be 1.29x108cfu/ml/g. The highest TVBC (1.38x108cfu/ml) was from the yogurt sample and the lowest (1.26x108cfu/g) was from meat. The overall prevalence of coagulase positive S. aureus (CoPS) was 39.1% (111) and of the smaples, 51(56.04%), 38(26.20%) and 22(45.83%) were isolated from meat, raw milk, and yogurt, respectively. There was a statistically significant difference (p<0.05) among the different sample types and sources in the prevalence of S. aureus. Almost half of the CoPS isolates were sensitive to Tetracycline, Gentamycin, and Kanamycin, but resistant to Amoxicillin (96.9%) and Penicillin G (93.8%). Moreover, 93.75% of the isolates developed multidrug resistance. All isolates carried the fem A gene and among these isolates, 12 (37.5%) carried mec A gene.

Conclusion:

The present study revealed that foods of bovine origin of the study area are found to be having less bacteriological quality, high prevalence of CoPS and development of drug resistance.

Isolation and Identification of Methicillin-Resistant Staphylococcus aureus (MRSA) from Milk in Shire Dairy Farms, Tigray, Ethiopia

Antibiotic-resistant Staphylococcus aureus isolates pose a severe challenge to both veterinary and health professions and dairy cattle producers. Cross-sectional study was conducted from November 2014 to May 2015 to isolate and identify S. aureus from mastitic cows' milk and estimate the occurrence of MRSA in the dairy farms of Shire. Physical examination and California mastitis test were performed on a total of 220 dairy cows. Bacteriological isolation and identification and antibiogram testing were performed. Furthermore, multiplex polymerase chain reaction (PCR) was done for the detection of mec A and fem A genes. Out of the 220 dairy cows, 64 (29.09%) were positive for bovine mastitis, and of these, 32.81% were coagulase-positive S. aureus (CoPS). Antibiogram test results showed 100% of the isolates were resistant to penicillin G, nalidixic acid, and ampicillin, and 33.33% of the CoPS showed resistance to oxacillin (phenotypically MRSA positive). But 38.09% of the CoPS were found to be resistant and susceptible to vancomycin. PCR amplification of the seven phenotypically MRSA isolates revealed that 42.9% and 71.4% of them were found to carry fem A and mec A genes, respectively. The current study revealed the existence of alarming level of CoPS and development of multidrug resistance.

Review on Major Food-Borne Zoonotic Bacterial Pathogens

Food-borne microorganisms are major pathogens affecting food safety and cause human illness worldwide as a result of consumption of foodstuff, mainly animal products contaminated with vegetative pathogens or their toxins. Most of these microbes have zoonotic importance resulting in significant impact on both public health and economic sectors. Bacteria are the causative agents of two-thirds of human food-borne diseases worldwide with high burden in developing countries. Hence, the objectives of this review paper are to highlight the background of food-borne bacterial pathogens and to review common major food-borne zoonotic bacterial pathogens. Food animals are the major reservoirs of many food-borne zoonotic bacterial pathogens, and food products of animal origin are the main vehicles of transmission. Meat, dairy products, and eggs are the main ways by which people are exposed to zoonotic bacteria. S. aureus, Salmonella species, Campylobacter species, L. monocytogenes, and E. coli are the major zoonotic bacterial pathogens which are the causative agents of food-borne illness and death in the world associated with consumption of contaminated animal products. Production of toxins and structural virulent factors are responsible for the pathogenesis of these bacteria. These major zoonotic bacteria cause human infections which are characterized mainly by gastrointestinal symptoms including nausea, vomiting, diarrhea, abdominal cramps, and other agent-specific symptoms. Some bacteria may cause severe complications. Conventional (culturing), serological, and molecular techniques are important for detection of these common zoonotic bacteria and their toxins in food. Good hygiene, GMP, sanitation in operating procedures, and implementation of standardized HACCP and pasteurization procedures are effective methods for the control and prevention. Currently, the emergence of multidrug-resistant zoonotic bacteria associated with consumption of contaminated animal products is a great concern for the public health, and there should be coordinated surveillance and monitoring system for food-borne zoonotic bacterial pathogens particularly in developing countries including Ethiopia.

Milk-borne bacterial health hazards in milk produced for commercial purpose in Tigray, northern Ethiopia

Background

Milk being a suitable medium for bacterial growth, it can serve as a source of bacterial contamination. Pathogenic bacteria in milk pose a serious health threat to humans and constitute about 90% of all dairy-related diseases. However, there are few studies that examined the health hazards of raw milk consumption in Ethiopia. Therefore, the objective of this study was to assess the prevalence of bacterial contamination and associated factors in milk produced for commercial purpose in Tigray region, northern Ethiopia.

Methods

This study used a cross-sectional study design, selected 315 persons (168 cafeterias, 96 dairy farms, and 51 milk vendors) for interview and collected the same number of bulk raw milk samples using systematic sampling procedure. Data were collected on socio-demographic, farm hygiene and milk handling practices by trained health professionals. Bacterial contamination was defined as total bacterial count (TBC) > 1 × 10⁵, staphylococcus count (SC) > 10⁵, or coliform count (CC) > 10² CFU/ml by culture and the species of bacteria were determined by standard biochemical tests.

Results

From the 315 milk samples tested, the prevalence of bacterial contamination was 52% (95% CI: 46.5–57.6). The mean counts of contaminated samples of TBC, SC, and CC were 8.94 ± 0.46 Standard Deviation (SD), 8.52 ± 0.6 SD, and 8.78 ± 0.49 SD log CFU/ml, respectively. The proportion of contamination was significantly lower in milk collected from dairy farms (32/96, 33.3, 95% CI: 24.5–43.2) compared to milk from vendors (33/51, 64.7, 95% CI: 51.4–66.2) and cafeterias (99/168, 58.9, 95% CI, 50.9–76.85). The milk samples were culture-positive for Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, K. oxytoca and Citrobacter freundii.

Conclusions

Over half of the sampled raw milk exhibited bacterial contamination with increasing trend from farmers to points of sale. Thus, milk vendors and cafeteria owners should apply good hygienic and sanitation practices during handling of milk; use appropriate, clean containers, and cold chain during milk transportation; and refrigeration of milk during storage.

Pastoral community practices, microbial quality and associated health risks of raw milk in the milk value chain of Nakasongola District, Uganda

The informal milk value chain in Uganda controls most of the raw marketed milk, albeit of poor quality. A study was conducted to assess the milk handling practices, the bacterial quality and the associated health concerns of raw milk along the informal milk value in Nakasongola District. The cross-sectional study used both qualitative and quantitative methods to obtain information from key players. The qualitative data was categorized and presented into emerging themes. Bacterial contamination of 200 milk samples was determined by morphological and biochemical tests. The antibiotic susceptibility test was done by the disc diffusion method.

Hand milking was carried out mainly by men (92.5%), and most never or rarely practised hand washing (67.5%) during milking. Milk was mainly delivered to mobile milk-collecting centres located under tree shades (50%). The quality of raw milk was affected by poor hygienic, handling and transportation practices. Most participants (75%) were aware of the dangers of drinking raw milk and the requirements to transport milk in metallic cans. Viable bacterial counts above the recommended limit were recorded in 76 samples (38%) that included Staphylococcus aureus (46%), coagulase-negative Staphylococcus (29%), Escherichia coli (12%), Streptococcus agalactiae (8%) and Salmonella spp. (5%). The overall antibiotic resistance was 45% (34/76), which included resistant isolates of S. aureus (17/34), coagulase-negative Staphylococcus (11/22), S. agalactiae (3/6), Salmonella spp. (2/4) and E. coli (2/9).

The raw milk contaminated with antibiotic drug-resistant bacterial pathogens is of public health concern. Thus, measures to improve the quality of milk need to be designed for the pastoral community in Nakasongola district.

Enterotoxigenicity and Antibiotic Resistance of Coagulase-Negative Staphylococci Isolated from Raw Buffalo and Cow Milk

Staphylococcal food poisoning is considered to be one of the most common foodborne illnesses worldwide. Because milk is rich in nutrients and its neutral pH, it leads to the growth of various bacteria. To date, the correlation between enterotoxigenic potential in Staphylococcus species and antimicrobial resistance (AMR), using bioinformatics analysis in buffalo and cow raw milk and the possible health risks from these bacteria, has not been examined in Egypt. A total of 42 Staphylococcus isolates representing 12 coagulase-positive staphylococci (Staphylococcus aureus and Staphylococcus intermedius) and 30 coagulase-negative staphylococci (Staphylococcus capitis, Staphylococcus xylosus, Staphylococcus carnosus, Staphylococcus saccharolyticus, and Staphylococcus auricularis) were isolated. An assay of the antimicrobial resistance phenotypes indicated low resistance against vancomycin (9.5%). The blaZ gene was associated with penicillin G and methicillin resistance and not with sulbactam + ampicillin. The presence of the gene ermB presented the correlation with erythromycin resistance and tetK with tetracycline resistance (correlation index: 0.57 and 0.49, respectively), despite the absence of the same behavior for ermC and tetM, respectively. Interestingly, the gene mecA was not correlated with resistance to methicillin or any other β-lactam. Correlation showed that slime-producing isolates had more resistance to antibiotics than those of nonslime producers. The multiple correlations between antibiotic resistance phenotypes and resistance genes indicate a complex nature of resistance in Staphylococcus species. The antimicrobial resistance could potentially spread to the community and thus, the resistance of Staphylococcus species to various antibiotics does not depend only on the use of a single antimicrobial, but also extends to other unrelated classes of antimicrobials.

Milk Safety Assessment, Isolation, and Antimicrobial Susceptibility Profile of Staphylococcus aureus in Selected Dairy Farms of Mukaturi and Sululta Town, Oromia Region, Ethiopia

A cross-sectional study was conducted to estimate the prevalence of Staphylococcus aureus in raw milk and swab, to assess the antimicrobial susceptibility profile, milk handling practice, and its associated risk factors in selected dairy farms of Mukaturi and Sululta Town, Oromia Region, Ethiopia. A total of 247 samples collected from dairy farms were examined using standard microbiological techniques. The antimicrobial susceptibility profiles of the isolates were also investigated. The possible risk factors for Staphylococcus aureus contaminations in milk were evaluated through a structured questionnaire. Overall, 16.6% (n= 41) of the samples were positive for S. aureus. The prevalence of S. aureus was 15.3% from udder milk and 25%, 20%, and 10% from milkers' hand, milking bucket, and drying towel swab, respectively. The prevalence of Staphylococcus aureus in milk showed statistically significant variation with respect to age (p≤ 0.001), parity (P≤ 0.001), drainage condition of milking area (P=0.035), study sites (P=0.035), and management system (P=0.035). Majority of the isolates were found resistant to penicillin G (97.6%) and amoxicillin (43.9%). According to this study, 12/28(42.9%) Staphylococcus aureus positive raw milk samples had 10⁴-10⁵cfu/ml S. aureus count, which is above the recommended level for human consumption. 47.1% of milking persons store milk at room temperature temporarily (between 6 and 12 hrs) till transport to collection center with no means of cooling aid. From consumers 25.6% had no health risk associated with raw milk consumption or aware of milk borne disease associated with drinking raw milk. Thus, 60.5% of milk users had habit of raw milk consumption. The study revealed a prevalence of S. aureus, poor milk handling practices, raw milk consumption behavior in study area. Proper handling and hygiene decrease milk contamination by S. aureus and make it safe for human consumption.

Bacteriological quality and safety of ready-to-consume milk and naturally fermented milk in Borana pastoral area, southern Ethiopia

Milk and milk products play an important role in the diet of pastoralists in Ethiopia. However, only few studies have been conducted on the microbial contamination of milk and milk products in pastoral areas. Therefore, the objective of the present study was to assess the hygiene and safety of ready-to-consume milk and traditionally produced fermented milk products (yogurt) in Borana. A total of 203 raw milk and milk product samples collected from different points along the milk production and handling chains were tested for Escherichia coli, E. coli O157:H7, and Staphylococcus aureus. E. coli was detected in 51.7% of the analyzed samples with a mean count of 2.5 logCFU/ml. The study revealed that 10.8% and 2.5% of the milk and dairy product samples harbor S. aureus and E. coli O157:H7, respectively. Detection of E. coli O157:H7 in ready-to-consume milk has potential health implications for consumers in an area where raw milk consumption is common. To our knowledge, this is the first report of the isolation of E. coli O157:H7 from milk in pastoral systems in Ethiopia.

Prevalence, resistance pattern, and molecular characterization of Staphylococcus aureus isolates from healthy animals and sick populations in Henan Province, China

Background

Staphylococcus aureus is one of the most prevalent pathogens and a causative agent of a variety of infections in humans and animals. A total of 640 samples were collected from healthy animals and patients from 2013 to 2014 in Henan Province, China, to investigate the prevalence and perform molecular characterization of S. aureus. Antimicrobial resistance and virulence genes were determined and pulsed-field gel electrophoresis (PFGE) and staphylococcal cassette chromosome mec (SCCmec) typing were performed.

Results

Overall, 22.3% (n = 143) of the samples were positive for S. aureus. The prevalence of methicillin-resistant S. aureus (MRSA) was 5.59%. Capsular polysaccharide locus type 5 (Cap5; 56.64%) was the dominant serotype. S. aureus strains showed high resistance to penicillin (96.50%), ciprofloxacin (52.45%), amikacin (67.83%), erythromycin (96.50%), lincomycin (97.20%), and tetracycline (68.53%) and 109 (76.2%) isolates harbored six or more tested resistance genes. The most predominant resistance genes were aphA (52.45%), ermC (53.15%), and tetM (52.45%). Eighty-seven (60.8%) isolates harbored six or more tested virulence genes. The most predominant enterotoxin genes were sed (20.28%), sej (20.98%), sep (14.69%), and set (37.76%). The prevalence of lukED gene was (57.34%), and a small number of isolates carried pvl (5.59%) and TSST-1 (2.80%). A total of 130 (82.52%) isolates could be typed by PFGE with SmaI digestion. PFGE demonstrated that 45 different patterns (P) that were grouped into 17 pulsotypes and 28 separate pulsotypes using a 90% cut-off value. A total of 118 (82.52%) isolates were successfully typed by spa, and 26 spa types were identified, t15075 (14.00%) and t189 (12.59%) were the most common types. SCCmec types were detected from eight MRSA isolates, with the most prevalent type being SCCmec IVa. MRSA-SCCmec Iva-t437 was observed in human isolates.

Conclusion

This study revealed a high prevalence of S. aureus in healthy animals and patients from Henan Province, China. Resistant S. aureus exhibited varying degrees of multidrug resistance. The presence of antibiotic resistance and virulence genes may facilitate the spread of S. aureus strains and pose a potential threat to public health, highlighting the need for vigilant monitoring of these isolates at the human–animal interface.

Electronic supplementary material

The online version of this article (10.1186/s13099-018-0254-9) contains supplementary material, which is available to authorized users.

Plectranthus amboinicus essential oil and carvacrol bioactive against planktonic and biofilm of oxacillin- and vancomycin-resistant Staphylococcus aureus

Background

The emergence of multidrug-resistant bacteria is a worldwide concern and in order to find an alternative to this problem, the occurrence of antimicrobial compounds in Plectranthus amboinicus essential oil was investigated. Thus, this study aims to determine susceptibility of Staphylococcus aureus isolated from food to antibiotics, P. amboinicus essential oil (PAEO) and carvacrol.

Methods

Leaves and stem of P. amboinicus were used for extraction of essential oil (PAEO) by hydrodistillation technique and EO chemical analysis was performed by gas chromatography coupled to a mass spectrometer. S. aureus strains (n = 35) isolated from food and S. aureus ATCC 6538 were used to evaluate the antimicrobial and antibiofilm activity of PAEO and carvacrol. All strains (n = 35) were submitted to antimicrobial susceptibility profile by disk diffusion method. Determination of MIC and MBC was performed by microdilution technique and antibiofilm activity was determined by microtiter-plate technique with crystal violet assay and counting viable cells in Colony Forming Units (CFU).

Results

Carvacrol (88.17%) was the major component in the PAEO. Antibiotic resistance was detected in 28 S. aureus strains (80%) and 12 strains (34.3%) were oxacillin and vancomycin-resistant (OVRSA). From the 28 resistant strains, 7 (25%) showed resistance plasmid of 12,000 bp. All strains (n = 35) were sensitive to PAEO and carvacrol, with inhibition zones ranging from 16 to 38 mm and 23 to 42 mm, respectively. The lowest MIC (0.25 mg mL⁻¹) and MBC (0.5 mg mL⁻¹) values were observed when carvacrol was used against OVRSA. When a 0.5 mg mL⁻¹ concentration of PAEO and carvacrol was used, no viable cells were found on S. aureus biofilm.

Conclusion

The antibacterial effect of carvacrol and PAEO proves to be a possible alternative against planktonic forms and staphylococcal biofilm.