Evaluation of the hygienic quality and associated public health hazards of raw milk marketed by smallholder dairy producers in the Dar es Salaam region, Tanzania

Occurrence of Methicillin-Resistant Staphylococcus aureus (MRSA) in Bovine Bulk Milk and Farm Workers in Smallholder Dairy Farming Systems in Northwestern Ethiopia

Background and Purpose

Staphylococcus aureus is a common pathogen responsible for causing various human and animal infections and is well known for its ability to develop resistance to multiple antibiotics. This study aimed to evaluate the occurrence of methicillin-resistant Staphylococcus aureus (MRSA) in bulk milk and dairy farms in northwestern Ethiopia and to determine their phenotypic and genotypic antimicrobial susceptibility patterns.

Methods

We collected 50 bulk milk samples from 50 dairy farms and 50 hand swabs from dairy milkers. The cefoxitin disk diffusion test and PCR-based assays were used to identify MRSA isolates. In addition, cefoxitin-resistant isolates were tested for susceptibility to other antibiotics using the Kirby-Bauer disk diffusion method.

Results

The results showed that MRSA was detected in 8 samples: 6 from bulk milk samples (12%) and 2 from hand swabs (4%). All MRSA isolates exhibited a high resistance rate to penicillin (100%), followed by tetracycline (75%), ciprofloxacin (25%), chloramphenicol (25%), erythromycin (25%), gentamycin (12.5%), and trimethoprim-sulfamethoxazole (12.5%). Moreover, 72% of the isolates showed resistance to three or more antibiotic classes and were classified as multidrug-resistant.

Conclusion

This study identified methicillin-resistant Staphylococcus aureus and multidrug-resistant MRSA in bulk milk and dairy farms in northwestern Ethiopia. These findings highlight the potential risk of transmission of these antibiotic-resistant bacteria to humans and the need for improved antibiotic stewardship in the dairy sector using the One Health approach.

Assessing milk products quality, safety, and influencing factors along the dairy value chain in eastern Democratic Republic of the Congo

Dairying is one of the new promising economic sectors in eastern Democratic Republic of Congo (DRC), but still not explored enough to ensure consumers' safety. This study aimed to assess the health risks and nutritional profile of milk products along the value chain in South-Kivu and Tanganyika provinces. A total of 288 milk actors, including 160 producers, 35 collectors and 93 vendors, were concerned for interview and milk samples collection. A total of 302 milk samples (159 raw, 44 pasteurized, 76 fermented and 19 white cheese so-called “Mashanza”) were collected for physicochemical [pH, fat, non-fat dry matter (NFDM), lactose, protein, freezing point, density] and microbiological (total Aerobic Mesophilic Flora, Escherichia coli, Total Coliforms, Fecal Coliforms, Salmonella and Staphylococci) analyses. Results revealed that the physicochemical characteristics of the milk mostly varied according to the type of milk and the regions. The pasteurized milk from Tanganyika presented the best physicochemical parameters [crude protein (CP) = 4.36%, Fat = 4.06%, NFDM = 12%, lactose = 5.4%, density = 1.02 and pH = 6.59] compared to other types of milk. For microbiology, no E. coli was recorded but Salmonella and Staphylococci were found in all the milk types with the values not exceeding 3 × 104 CFU ml−1 and 3 × 103 CFU ml−1, respectively. This implies a long-term consumers' health issue if appropriate measures are not taken by milk actors along the value chain. The microbiological quality was influenced by the ecologies of production axis (representing the production zones) and by handling methods and infrastructures used by the actors involved along the value chain. Factors related to animal husbandry, milking method, milk processing and packaging had no significant effect on the physicochemical parameters under study. These results indicated that health risks for milk consumers are accrued by production practices and handling by milk actors due to shortage of required skills and appropriate equipment along the milk value chain. Observance of hazard analysis critical control point (HACCP) measures is carefully required along the milk value chain nodes to improve the quality of milk produced and sold and thus reduce the risks among consumers in South-Kivu and Tanganyika provinces.

Antibiotics in Dairy Production: Where Is the Problem?

Antibiotics have long been used for the prevention and treatment of common diseases and for prophylactic purposes in dairy animals. However, in recent decades it has become a matter of concern due to the widespread belief that there has been an abuse or misuse of these drugs in animals and that this misuse has led to the presence of residues in derived foods, such as milk and dairy products. Therefore, this review aims to compile the scientific literature published to date on the presence of antibiotic residues in these products worldwide. The focus is on the reasons that lead to their presence in food, on the potential problems caused by residues in the characteristics of dairy products and in their manufacturing process, on the development and spread of antibiotic-resistant bacteria, and on the effects that both residues and resistant bacteria can cause on human and environmental health.

High prevalence of antibiotic resistance in pathogenic foodborne bacteria isolated from bovine milk

This study aimed to investigate the prevalence of foodborne pathogenic bacteria in bovine milk, their antibiogram phenotype, and the carriage of antibiotic resistance genes. Raw bovine milk samples (n = 100) were randomly collected from different suppliers in the northwest of Iran. Antibiotic-resistant patterns and the presence of antibiotic resistance genes were evaluated in the isolates. Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, and Salmonella spp. were isolated from 78%, 47%, 25%, and 21% of samples, respectively. All isolates showed high rates of resistance to amoxicillin, penicillin, and cefalexin. The bla_TEM and bla_SHV genes were detected in 50.0% and 6.4% of E. coli isolates, respectively. Also, 28.5% and 19.0% of Salmonella isolates were positive for bla_TEM and bla_SHV. The frequency of mecA and bla_Z in S. aureus isolates was 20.0% and 12.0%, respectively. The high prevalence of bovine milk contamination with antimicrobial-resistant species in this study necessitates precise control on antibiotic prescription in veterinary medicine.

Assessment of Milk Quality and Food Safety Challenges in the Complex Nairobi Dairy Value Chain

Food networks present varying food safety concerns because of the complexity of interactions, production, and handling practices. We investigated total bacteria counts (TBCs) and total coliform counts (TCCs) in various nodes of a Nairobi dairy value chain and identified practices that influence food safety. A value chain analysis framework facilitated qualitative data collection through 23 key informant interviews and 20 focus group discussions. Content thematic analysis identified food safety challenges. Cow milk products (N = 290) were collected from farms (N = 63), collection centers (N = 5), shops/kiosks (N = 37), milk bars (N = 17), roadside vendors (N = 14), restaurants (N = 3), milk vending machines (N = 2), mobile traders (N = 2) and a supermarket (N = 1). Mean values of colony-forming units for TBC and TCC were referenced to East African Standards (EAS). Logistic regression analysis assessed differences in milk acceptability based on EAS. The raw milk from farms and collection centers was relatively within acceptable EAS limits in terms of TBC (3.5 × 10⁵ and 1.4 × 10⁶ respectively) but TCC in the milk from farms was 3 times higher than EAS limits (1.5 × 10⁵). Compared to farms, the odds ratio of milk acceptability based on TBC was lower on milk bars (0.02), restaurants (0.02), roadside vendors (0.03), shops/kiosks (0.07), and supermarkets (0.17). For TCC, the odds that milk samples from collection centers, milk bars, restaurants, roadside vendors, and shops/kiosks were acceptable was less than the odds of samples collected from farms (0.18, 0.03, 0.06, 0.02, and 0.12, respectively). Comparison of raw milk across the nodes showed that the odds of milk samples from restaurants, roadside vendors, and shops/kiosks being acceptable were less than the odds of samples collected the farm for TBC (0.03, 0.04, and 0.04, respectively). For TCC, the odds of raw milk from collection centers, restaurants, roadside vendors, milk bars, and shops/kiosks being acceptable were lower than the odds of acceptability for the farm samples (0.18, 0.12, 0.02, 0.04, and 0.05, respectively). Practices with possible influence on milk bacterial quality included muddy cowsheds, unconventional animal feed sources, re-use of spoilt raw milk, milk adulteration, acceptance of low-quality milk for processing, and lack of cold chain. Therefore, milk contamination occurs at various points, and the designing of interventions should focus on every node.

Antimicrobial Residues in Food from Animal Origin-A Review of the Literature Focusing on Products Collected in Stores and Markets Worldwide

The extensive use of antibiotics leads to antibiotic residues in frequently consumed foods. Generally, the main use of antibiotics in animals is to treat and prevent diseases and growth promotion. However, the residues and their breakdown products have several side effects on the human body and, in a broader sense, on the environment. In relation to the human body, the frequency of mutations is increased, the bone marrow is damaged (chloramphenicol), and the reproductive organs of humans are affected. Carcinogenic effects have been found with antibiotics such as sulfamethazine, oxytetracycline, and furazolidone. We summarized data from 73 scientific studies reporting antimicrobial residues in animal products that were freely available for sale. The studies were published in English starting from 1999 till 2021 and identified through the Pubmed search engine. The aims were to find out which antibiotics, legal or illegal, could be found in animal foods worldwide. Which are stable to get into the food chain and exceed the maximum residue limits (MRL) regarding the EU guidelines as a comparison. Reducing antimicrobial residues in food from animal origin and, in addition to this, fighting the tremendous growth and spread of antimicrobial resistance will undoubtedly be one of the most difficult food safety challenges in the coming years.

Antimicrobial Use, Residues, Resistance and Governance in the Food and Agriculture Sectors, Tanzania

All infections are potentially curable as long as the etiological agents are susceptible to antimicrobials. The increased rate at which antimicrobials are becoming ineffective is a global health risk of increasing concern that threatens withdrawal of beneficial antimicrobials for disease control. The increased demand for food of animal origin, in particular eggs, meat and milk has led to intensification and commercial production systems where excessive use and misuse of antimicrobials may prevail. Antimicrobials, handled and used by farmers and animal attendants with no formal education, may be predisposed to incorrect dosages, misuse, incorrect applications and non-adherence to withdrawal periods. This study was conducted to assess the regulatory roles and governance of antimicrobials, establish the pattern and extent of their use, evaluate the antimicrobial residues and resistance in the food animals and crop agriculture value chains, and relate these findings to existing strategies in place for combating the emergence of antimicrobial resistance in Tanzania. A multimethod approach (desk review, field study and interviews) was used. Relevant establishments were also visited. High levels of resistance to penicillin G, chloramphenicol, streptomycin and oxytetracycline have been reported, especially for Actinobacter pyogenes, Staphylococcus hyicus, Staphylococcus intermedius and Staphylococcus aureus from dairy cattle with mastitis and in humans. Similar trends were found in poultry where eggs and meat are contaminated with Escherichia coli strains resistant to amoxicillin + clavulanate, sulphamethoxazole and neomycin. An increasing trend of emerging multidrug resistant E. coli, Klebsiella pneumoniae, Staphylococcus aureus and Salmonella was also found in food animals. An increase in methicillin resistant Staphlococcus aureus (MRSA) and extended-spectrum beta-lactamase (ESBL) in the livestock sector in Tanzania have been reported. The pathogens isolated in animals were resistant to ampicillin, augmentin, gentamicin, co-trimoxazole, tetracycline, amoxicillin, streptomycin, nalidixic acid, azithromycin, chloramphenicol, tylosin, erythromycin, cefuroxime, norfloxacin and ciprofloxacin. An increased usage of antimicrobials for prophylaxis, and therapeutics against pathogens and for growth promotion in livestock, aquaculture and crop production were observed. A One Health strategic approach is advocated to combat antimicrobial resistance (AMR) in the food and agriculture sectors in Tanzania. Practical recommendations include (a) legislation review and implementation; (b) antimicrobial use (AMU), AMR and antimicrobial residue (AR) awareness and advocacy among stakeholders along the value chain; (c) strengthening of surveillance and monitoring programs for AMU, AMR and AR; (d) enhanced development and use of rapid and innovative diagnostic tests and the promotion of biosecurity principles; and (e) good husbandry practices. The utilization of this information to improve public health policies and reduce the burden of AMR will be beneficial.

A survey of management practices and major diseases of dairy cattle in smallholdings in selected towns of Jimma zone, south-western Ethiopia

Context Smallholder dairy farming is becoming an important source of food, income and employment for many urban dwellers in Ethiopia. However, suboptimal productivity is a major constraint due to diseases and poor management practices. Aims The present work aimed at assessing management practices, dairy cattle diseases, and methods used by farmers to identify diseases on smallholdings in selected towns of Jimma zone, south-western Ethiopia. Methods Data for the study were obtained by surveying 52 dairy-keeping farmers by using a semi-structured questionnaire and personal observations. Key results The mean herd size of indigenous and crossbred cattle was 5 ± 0.04 and 2 ± 0.4 respectively. Natural pasture was the main source of feed with supplementation, mainly with agro-industrial by-products, concentrate mixes, non-conventional feeds and crop residues. In total, 75% of the respondents practiced a free-grazing system. Most (64%) of the respondents used natural service for breeding. In all, 64% and 35% of the respondents washed their hands and the teats respectively, before milking. In the order of decreasing percentage of respondents, the most frequently reported dairy cattle health problems were tick infestation, mastitis, lumpy skin disease, blackleg, heart water, facioliasis, trypanosomiasis, foot-and-mouth disease, pasteurellosis, brucellosis and anthrax. Repeated breeding, retained fetal membranes, abortion, stillbirths and dystocia were the common reproductive health problems, in a decreasing order of the reported percentage. Lumpy skin disease was reported as a major cause of calf and lactating-cow deaths. A total of 89% of the respondents used veterinary medicines to treat their sick animals. About 24% of the respondents stated culling of their animals due to old age, lack of space, infertility, feed shortage, need for cash and low production, in a decreasing order of importance. Conclusions The results showed farmers are well knowledgeable in cattle production practices and are actually mitigating effects of most disease challenges in their farms, which may have resulted in low milk productivity. Implications The farmers in the current study had some knowledge of milk production activities that may be recommended for similar settings, especially on how to manage dairy cattle production under smallholder farms, obviously including the occurrence of diseases, which they are managing appropriately with available technologies including vaccines and treatment. These could be used as baseline data by dairy stakeholders and policy makers during the formulation and implementation of policies for sustainable growth and development of smallholder dairy for similar settings.

Isolation and characterization of E. coli strains causing intramammary infections from dairy animals and wild birds

The study was conducted to estimate the prevalence of Escherichia coli (E. coli) in sub-clinically mastitic (SCM) animals, and in wild and migratory birds which may act as reservoir disseminating such pathogen. Farm hygiene, management and milking procedures were listed through a questionnaire. Thirty lactating cows and 15 lactating buffaloes from five small-scale dairy farms were randomly selected and screened for subclinical mastitis (SCM) using California Mastitis Test (CMT) and somatic cell count (SCC). In addition, 80 teat skin swabs, 5 drinking water samples and 38 wild and migratory bird faecal matter were also collected. All samples were processed for E. coli isolation by culturing on Levine’s Eosin Methylene Blue (L-EMB) agar, followed by purification and biochemical identification. Positive samples were subjected to molecular identification and serotyping. In addition, the presence of extended-spectrum beta-lactamase (ESBL) and carbapenemase-producing E. coli have been reported by antimicrobial sensitivity testing. Escherichia coli were isolated from 7.7%, 50% and 50% of the positive CMT cows’ quarters, cows’ composite and buffaloes’ composite milk samples, respectively. In addition, 14% of cows’ teats, 20% of water samples, 70% of faecal matter from wild bird, and 33.3% of faecal matter from migratory waterfowls were carrying E. coli. Serotyping, antibiotic-resistant pattern and phylogenetic analysis have pointed the bearable implication of milking hygiene and wild birds in disseminating E. coli strains causing intramammary infections.

Milk handling practices and consumption behavior among Borana pastoralists in southern Ethiopia

BACKGROUND

Safety and wholesomeness of milk intended for human consumption are influenced by various interlinked factors. However, information on what these factors are, especially in the pastoral traditional communities of Ethiopia, is largely lacking. The objective of this study is to assess the hygienic milk production, processing and consumption practices, and behaviors of Borana pastoralists.

METHODS

The study used qualitative participatory research methods. Individual semi-structured interviews, focus group discussions, informal discussions, and observations were carried out on (1) milk handling practices, (2) perceptions of quality and safety of milk, including perceived criteria for good milk, (3) awareness of milk-borne diseases, and (4) perception towards milk boiling practices. The interviews and discussions were audio recorded, transcribed, and analyzed by identifying themes.

RESULTS

Some risky behaviors related to milk handling and consumption were identified. These include unhygienic conditions in handling milk and milk products, consumption behaviors such as consuming raw milk purchased from markets, and children directly consuming milk from the udder of animals (e.g., goats). There was a very strong reluctance to boil milk before consumption mainly because of the misconception that nutrients in the milk are destroyed when milk is boiled and "boiled milk is dead". On the other hand, potential risk mitigation practices were identified such as smoking of milk containers (which may help reduce microbial growth), processing milk through fermentation, consuming milk in boiled tea, and a recent trend towards boiling milk for babies. However, the latter was not motivated by concern over microbial hazards but the belief that raw milk could form curds in children's stomach which might then suffocate them.

CONCLUSION

The findings highlight the need to promote hygienic handling practices of milk and closely engage with local communities to improve their understanding of milk safety to facilitate change in practices. Educating pastoralists on good milk production practices should be given priority. One of the ways to do this could be by strengthening the integration of milk hygiene in research and development programs as an entry point for behavioral change towards the safe handling and consumption of milk and milk products.

Assessment of Raw Cow Milk Quality in Smallholder Dairy Farms in Pemba Island Zanzibar, Tanzania

Milk quality depends on the physicochemical characteristics, hygienic standards, and nutritional quality; however, animal husbandry practices, unhygienic harvesting and processing, may affect its quality. A cross-sectional study was conducted between August 2010 and July 2011 to assess the hygiene of cow milk production environment, raw cow milk physicochemical characteristics, and microbial quality and estimate the prevalence of antimicrobial residues using standard methods in Pemba Island. A total of 98 raw cow milk samples from selected smallholder dairy farms were analyzed, and the judgement on the quality used the East African Standards. Generally, the milk production chain was done under the unhygienic condition, and dirty plastic containers were used for collection and storage of milk under room temperature. Some milk samples had abnormal colour (2.1%), abnormal smell (7.1%), and pH below normal (35.7%), clotted on alcohol test (9.2%), and had the specific gravity below normal (13.3%). All the milk samples had mineral contents within the recommended range. Milk samples with butterfat below normal were 29.6%, while 14.3% had total solids below recommended values. The mean total viable count (TVC) of milk container surfaces was 9.7 ± 10.5 log CFU/100 cm2, while total coliform count (TCC) was 7.8 ± 8.5 log CFU/100 cm2. Up to 55.1% of milk had TVC beyond the recommended levels. The milk mean TVC was 11.02 ± 11.6 log CFU/ml and TCC was 6.7 ± 7.3 log CFU/ml. Up to 26.5% of milk samples had the TCC beyond levels. Results on physicochemical characteristics and nutritional analysis show that the raw cow milk in Pemba Island is of inferior quality. Microbiological results of this study imply heavy contaminations of milk. Antimicrobial residues were detected in 83% of the samples and most of them were from Wete District. Unhygienic milk production chain accelerates microbial contaminations, and antimicrobial residues in milk are a big problem that needs urgent attention from the responsible authority.

Factors affecting milk quality of crossbred dairy cows in automated Herringbone milking system

The aim of the study was to investigate the effect of factors affecting milk quality of crossbred dairy cows milked in automated Herringbone milking system. The study was conducted on 37 crossbred Karan Fries cows of different parities, stages of lactation and udder types for 3 months. The milk quality was assessed based on milk composition, on-line electrical conductivity (EC) and peak conductivity, somatic cell count (SCC) and standard plate count (SPC) of milk samples. The results showed that there was no change in milk composition in terms of fat and SNF except in different parity groups. The milk conductivity was significantly higher in the late stage of lactation. However, no change in SCC values was observed. The udder types showed significant increase in EC values in udders with poor structure and loose attachment. The SCC values were also significantly higher for such udder types. The SPC was significantly higher when the number of milkings on each liner exceeded 2000 milkings/liner. The SCC was had a positive correlation with EC and SPC. The correlation between SPC and SCC was highly significant whereas, EC was moderately correlated with SPC. It can be concluded that the milk quality of crossbred dairy cows was significantly affected by parity, stages of lactation, udder type and liner usage in automated parlours. Therefore, effective management strategy needs to be taken to improve the quality of milk taking into consideration on-line EC, SCC and SPC.

Contamination Levels and Identification of Bacteria in Milk Sampled from Three Regions of Tanzania: Evidence from Literature and Laboratory Analyses

Milk in Tanzania has been reported to be contaminated with large number of bacteria. This is because (1) milk is obtained from animals with unknown health status, (2) good milking and handling practices are to a large extent not observed, and (3) marketing and distribution are done in informal channels. These factors are potential causes of milk-borne diseases and milk quality loss. The aim of this study was to assess nutritional risks in milk as reported in literature over a period of 20 years and through analyses of samples collected during the present study. The issues highlighted in literature were high bacteria and coliform counts exceeding standard levels in East Africa, prevalence of bacteria and drug residues in milk, and adulteration. Based on performed analyses, total bacterial count 1.0 × 10⁷ colony forming units per millilitre (cfu/ml) and total coliform count 1.1 × 10⁷ cfu/ml, also greater than recommended levels, were found. Ten bacteria types were isolated from milk samples (five, Pseudomonas aeruginosa, Listeria monocytogenes, Listeria innocua, Listeria ivanovii, and Klebsiella spp. are reported in Tanzanian for the first time). Two drugs tetracycline and sulphur were detected. Therefore, it is worth noting that integrated research is needed to evaluate the situation and address these challenges.

First Report on a Randomized Investigation of Antimicrobial Resistance in Fecal Indicator Bacteria from Livestock, Poultry, and Humans in Tanzania

This study provides an estimate of antimicrobial resistance in intestinal indicator bacteria from humans (n = 97) and food animals (n = 388) in Tanzania. More than 70% of all fecal samples contained tetracycline (TE), sulfamethoxazole (STX), and ampicillin (AMP)-resistant coliforms, while cefotaxime (CTX)-resistant coliforms were observed in 40% of all samples. The average Log₁₀ colony forming units/g of CTX-resistant coliforms in samples from humans were 2.20. Of 390 Escherichia coli tested, 66.4% were resistant to TE, 54.9% to STX, 54.9% to streptomycin, and 36.4% to CTX. Isolates were commonly (65.1%) multiresistant. All CTX-resistant isolates contained bla_CTX-M gene type. AMP- and vancomycin-resistant enterococci were rare, and the average concentrations in positive samples were low (log₁₀ 0.9 and 0.4, respectively). A low-to-moderate resistance (2.1-15%) was detected in 240 enterococci isolates to the drugs tested, except for rifampicin resistance (75.2% of isolates). The average number of sulII gene copies varied between Log₁₀ 5.37 and 5.68 with no significant difference between sample source, while cattle had significantly higher number of tetW genes than humans. These findings, based on randomly obtained samples, will be instrumental in designing antimicrobial resistance (AMR) intervention strategies for Tanzania.

A large meta-analysis of the global prevalence rates of S. aureus and MRSA contamination of milk

Past reports have indicated a high prevalence of milk contaminated with Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA), but the pooled prevalence rates of S. aureus and MRSA in pasteurized and boiled cow's milk, raw cow's milk, and raw Caprinae milk (raw sheep's milk and raw goat's milk) and across different periods, continents, economic conditions and purchase locations remain inconsistent. We searched relevant articles published in PubMed, EMBASE, and Web of Science before July 2016. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) Statement was used to evaluate the quality of 93 included studies. We observed that the pooled prevalence rates of S. aureus contamination in pasteurized and boiled cow's milk, raw cow's milk, and raw Caprinae milk were 15.4% (95% CI, 6.1-27.5%), 33.5% (95% CI, 29.5-37.7%) and 25.8% (95% CI, 17.5-35.0%), respectively. The pooled prevalence rates of MRSA contamination were 4.9% (95% CI, 0.0-15.7%), 2.3% (95% CI, 1.3-3.6%), and 1.1% (95% CI, 0.5-1.8%), respectively. The prevalence of S. aureus contamination in raw cow's milk increased over time. However, the pooled prevalence of raw cow's milk contaminated with S. aureus was lowest in European studies. These findings give an indication of the consequence of better milk regulation in Europe. High S. aureus prevalence rates in raw milk collected from farms and processing companies pose a potential threat to consumers. The implementation of good hygiene practices, appropriate health knowledge, and food safety principles at the farm level, as well as the prudent use of antibiotics in veterinary medicine and heat treatment before drinking, are necessary to reduce the potential risk of S. aureus and MRSA contamination.

Microbial contamination of water intended for milk container washing in smallholder dairy farming and milk retailing houses in southern Ethiopia

The water used during handling and processing of milk products can be potential sources of microbial contamination with possible negative consequences on food safety. Especially, the water used in keeping the hygiene of milking and milk storage utensils is crucial to keep the quality and safety of the products. Therefore, the current study was designed to assess the bacteriological quality of water used for cleaning milking and milk storage equipment in smallholder dairy production in Hawassa and its surroundings. A total of 79 water samples were collected: 26 from milk collecting houses in Hawassa and 53 from selected smallholder dairy farms (Hawassa = 14, Arsi Negele = 29 and Yirgalem = 10). Out of the total samples, 18 samples were collected directly from pipe and 61 from storage containers (46 from narrow opening and 15 from wide opening containers). The overall prevalence of E. coli exceeding zero CFU/ml was 39.2 %. From analyzed samples, high prevalence of positive samples for E. coli was found in water samples taken from wide opening containers (66.7 %). A number of bacteria were isolated and presumptively identified which include Bacillus sp. 6.3 % (n = 5), Citrobacter sp. 1.3 %(n = 1), E. coli 39.2 % (n = 31), Enterobacter sp. 2.5 % (n = 2), Klebisella sp. 7.6 % (n = 6), Micrococcus sp. 6.3 % (n = 5), Pseudomonas sp. 6.3 % (n = 5), Staphylococcus aureus 6.3 % (n = 5), Staphylococcus epidermidis 13.9 % (n = 11) and Streptococcus sp. 1.3 % (n = 1). The bacteriological quality of water especially, water stored in household storage containers in present study area was found to be contaminated with different bacteria indicating potential food safety problem and health risk to the society. In this respect, people handling water should be educated on its proper handling and the risk of contamination during storage. To minimize contamination, materials with narrow mouth and lid should be used. Further study is recommended on the relationship between the bacteriological quality of water and the behavior of water users.

Staphylococcus aureus in Animals and Food: Methicillin Resistance, Prevalence and Population Structure. A Review in the African Continent

The interest about Staphylococcus aureus (S. aureus) and methicillin resistant S. aureus (MRSA) in livestock, and domestic and wild animals has significantly increased. The spread of different clonal complexes related to livestock animals, mainly CC398, and the recent description of the new mecC gene, make it necessary to know more about the epidemiology and population structure of this microorganism all over the world. Nowadays, there are several descriptions about the presence of S. aureus and/or MRSA in different animal species (dogs, sheep, donkeys, bats, pigs, and monkeys), and in food of animal origin in African countries. In this continent, there is a high diversity of ethnicities, cultures or religions, as well as a high number of wild animal species and close contact between humans and animals, which can have a relevant impact in the epidemiology of this microorganism. This review shows that some clonal lineages associated with humans (CC1, CC15, CC72, CC80, CC101, and CC152) and animals (CC398, CC130 and CC133) are present in this continent in animal isolates, although the mecC gene has not been detected yet. However, available studies are limited to a few countries, very often with incomplete information, and many more studies are necessary to cover a larger number of African countries.

Survey of physicochemical characteristics and microbial contamination in selected food locally vended in Morogoro Municipality, Tanzania

BACKGROUND

Raw milk, raw fruit juice and raw fish are enriched with essential nutrients for human diet but are prone to microbial contamination along the value chain. This cross sectional study was conducted to assess physicochemical characteristics and microbial quality of raw milk, fruit juice and fish from food vendors in Morogoro Municipality, Tanzania. The physicochemical assessment of food samples was done by smell, colour, presence of debris, turbidity, consistence, pH and clot on alcohol test. Hygiene of food containers, personnel and the vending environment was also assessed. Qualitative and quantitative microbial assessment of food was done using standard laboratory protocols as described by Tanzania Bureau of Standards and International Systems of Standards.

RESULTS

Raw milk sold in Morogoro was of poor quality since was adulterated with water, contained sediments and clotted on alcohol test. Up to 63 % of the milk samples were contaminated with Escherichia coli and 60 % had higher total viable count (TVC) than the recommended values. Raw fruit juice was stored in dirty containers and sold under unhygienic environment. Seventy-three percent of juice samples had TVC beyond the recommendations while E. coli contamination rate was 63.3 %. The raw fish samples had started spoiling as depicted through sensory evaluation. E. coli contamination rate was 55 % and that of Campylobacter jejuni was 0.5 %. The mean TVC of raw fish was 8.1 (Log cfu/g) and 96.2 % of the fish samples had TVC beyond the recommended limits of 5.0 Log cfu/g.

CONCLUSIONS

The physicochemical characteristics of food vended in Morogoro Municipality were of poor quality. The food had high bacterial contaminations. This situation poses health risks to the public and losses to food vendors due to spoilage. Stakeholders in food value chain should be educated on safe production and good hygienic practices. Routine quality and safety assessment of locally vended food, inspection of selling premises and regular health check-up of the personnel involved in food vending industry should be instituted.

Prevalence and Antimicrobial Resistance of Campylobacter Isolated from Dressed Beef Carcasses and Raw Milk in Tanzania

Campylobacter species are commonly transmitted to humans through consumption of contaminated foods such as milk and meat. The aim of this study was to investigate the prevalence, antimicrobial resistance, and genetic determinants of resistance of Campylobacter isolated from raw milk and beef carcasses in Tanzania. The antimicrobial resistance genes tested included blaOXA-61 (ampicillin), aph-3-1 (aminoglycoside), tet(O) (tetracycline), and cmeB (multi-drug efflux pump). The prevalence of Campylobacter was 9.5% in beef carcasses and 13.4% in raw milk, respectively. Using multiplex-polymerase chain reaction (PCR), we identified 58.1% of the isolates as Campylobacter jejuni, 30.7% as Campylobacter coli, and 9.7% as other Campylobacter spp. One isolate (1.6%) was positive for both C. jejuni and C. coli specific PCR. Antimicrobial susceptibility testing using the disk diffusion assay and the broth microdilution method showed resistance to: ampicillin (63% and 94.1%), ciprofloxacin (9.3% and 11.8%), erythromycin (53.7% and 70.6%), gentamicin (0% and 15.7%), streptomycin (35.2% and 84.3%), and tetracycline (18.5% and 17.7%), respectively. Resistance to azithromycin (42.6%), nalidixic acid (64.8%), and chloramphenicol (13%) was determined using the disk diffusion assay only, while resistance to tylosin (90.2%) was quantified using the broth microdilution method. The blaOXA-61 (52.6% and 28.1%), cmeB (26.3% and 31.3%), tet(O) (26.3% and 31.3%), and aph-3-1 (5.3% and 3.0%) were detected in C. coli and C. jejuni. These findings highlight the extent of antimicrobial resistance in Campylobacter occurring in important foods in Tanzania. The potential risks to consumers emphasize the need for adequate control approaches, including the prudent use of antimicrobials to minimize the spread of antimicrobial-resistant Campylobacter.

Assessment of raw milk quality and stakeholders' awareness on milk-borne health risks in Arusha City and Meru District, Tanzania

A cross-sectional study was conducted to assess the quality of raw milk and stakeholders' awareness on milk-borne health risks and factors for poor milk hygiene in Arusha City and Meru District, Tanzania between October and December 2012. A total of 105 smallholder dairy farmers, milk vendors and milk retailers were interviewed, and milk samples were collected for physical, microbial and antibiotic residue analysis using standard procedures. Questionnaire results indicated high level of awareness (94 %) that drinking raw milk can predispose consumers to milk-borne diseases; nevertheless, 65 % of respondents consumed raw milk. Physicochemical analyses showed some of the milk had sediments (20 %), bad smell (21 %) and had clotted on alcohol test (27 %). About 36 % of milk samples had pH below 6.6, and 25 % had specific gravity below 1.028 g/ml. The mean total viable count (TVC) of milk from vendors is significantly (P < 0.05) higher than that from retailers and smallholder dairy farmers. Generally, 65 % of milk samples assessed had a higher TVC than the level recommended (2.0 × 10(5) cfu/ml) by the East African Community (EAC) standards. Up to 91 % of the milk samples had bacterial growth that included Eschericia coli (66 %), Staphylococcus aureus (33 %), Corynebacterium (11 %) and Pseudomonas (10 %). All smallholder dairy farmers were aware of drug residues, but majority (57 %) were unaware of human health effects caused by veterinary drug residues in milk. Up to 97 % of respondents reported to comply with drug withdrawal periods. This possibly led to all milk samples analysed to be negative from detectable levels of antibiotic residues. It is concluded that the level of awareness on milk quality is high, although practices associated with milking and post-harvest handling predispose milk to bacterial contamination which is a public health risk to milk consumers.

Smallholder farmers' attitudes toward the provision of drinking water for dairy cows in Kagera, Tanzania

Agriculture's large share of Tanzanian GDP and the large percentage of rural poor engaged in the sector make it a focus for many development projects that see it as an area of attention for reducing rural poverty. This paper uses a case of the Kamachumu community, where a dairy cow loan project was implemented using the heifer-in-trust (HIT) model. This study finds that productivity is limited by how the cows are being managed, particularly with many animals not having ad lib access to drinking water. The paper explores reasons why farmers do or do not provide their cows with unlimited access to drinking water. The study concludes that there are many barriers farmers face, including water accessibility, education and training, infrastructure, simple negligence, and security. These results suggest an increase in extension services and national and local livestock policies that consider the specific realities of small-scale dairy farmers.

Nutritional and hygienic quality of raw milk in the mid-northern region of Algeria: correlations and risk factors

This paper aims to study the overall quality of raw milk in the mid-northern region of Algeria. The analysis results showed a decrease in the average temperature for the delivery of 1,54°C with P<0.001. However, no significant variation (P>0.05) was observed in almost all the physical and nutritional parameters studied (pH, fat content, and protein content) between M1 and M2. The average contamination by total mesophilic aerobic bacteria (TMAB), coliforms, yeasts, molds, and different pathogens in samples taken at M1 showed significant changes at M2. This was confirmed by the decrease of reduction time of methylene blue (RTMB), about 54%. The variation was described as follows: (P>0.05) for yeasts and (P<0.05) for molds in M1 and M2, (P<0.05) for TMAB in M1, and (P<0.001) for TC, FC, and TMAB in M2. The analysis for the detection of Salmonella spp. showed no contamination in all samples tested, while antibiotic residues were detected in 35% of milks delivered. In conclusion, several risk factors have been identified in this study, namely, the effect of the season and the distance between the farm and the dairy unit.

Food safety management systems performance in African food processing companies: a review of deficiencies and possible improvement strategies

This study seeks to provide insight into current deficiencies in food safety management systems (FSMS) in African food-processing companies and to identify possible strategies for improvement so as to contribute to African countries' efforts to provide safe food to both local and international markets. This study found that most African food products had high microbiological and chemical contamination levels exceeding the set (legal) limits. Relative to industrialized countries, the study identified various deficiencies at government, sector/branch, retail and company levels which affect performance of FSMS in Africa. For instance, very few companies (except exporting and large companies) have implemented HACCP and ISO 22000:2005. Various measures were proposed to be taken at government (e.g. construction of risk-based legislative frameworks, strengthening of food safety authorities, recommend use of ISO 22000:2005, and consumers' food safety training), branch/sector (e.g. sector-specific guidelines and third-party certification), retail (develop stringent certification standards and impose product specifications) and company levels (improving hygiene, strict raw material control, production process efficacy, and enhancing monitoring systems, assurance activities and supportive administrative structures). By working on those four levels, FSMS of African food-processing companies could be better designed and tailored towards their production processes and specific needs to ensure food safety.

Microbiological quality of milk in Tanzania: from Maasai stable to African consumer table

In Tanzania, pastoralists such as the Maasai and small urban farmers are responsible for the country's milk production, and 95% of the national milk supply is sold without regulation. This study was conducted using hygiene checklists and milk sampling to investigate milk quality and safety at various steps throughout the milk production chain. In regions of Dar es Salaam and Lake Victoria, 196 milk samples were collected: 109 samples of raw milk, 41 samples of packed or open served heat-treated products, and 46 samples of fermented products. Samples were taken from (i) the production level (pastoralists and urban farmers), (ii) the collection level (middlemen and depots), (iii) processors (dairies), and (iv) retailers (kiosks). Samples were analyzed for hygiene criteria (total bacteria, total coliforms, Escherichia coli, and coagulase-positive staphylococci) and foodborne pathogens such as Salmonella, enterohemorrhagic E. coli O157:H7, and Listeria monocytogenes. Adequate heating of milk for drinking was determined via heat labile alkaline phosphatase and lactoperoxidase analysis. Total bacterial counts indicated that only 67% (73 of 109) of raw milk samples and 46% (19 of 41) of heat-treated samples met national Tanzanian standards. Bulk milk samples taken from the traditional milking vessels of Maasai pastoralists had the lowest total bacterial counts: ≥ 1 × 10(2) CFU/ml. Foodborne pathogens such as E. coli O157:H7 and Salmonella were isolated from 10.1% (11 of 109) of raw milk samples but were not detected in heat-treated or fermented products, and 83% of heat-treated milk samples were lactoperoxidase negative, indicating overpasteurization. Coliforms were detected in 41% (17 of 41) of processed milk samples, thus indicating a high rate of recontamination. A progressive decrease in microbial quality along the milk production chain was attributed to departures from traditional methods, inadequate milk containers, long transport distances, lack of cooling, and lack of a basic understanding of hygiene.

Constraints and challenges of meeting the water requirements of livestock in Ethiopia: cases of Lume and Siraro districts

Compared to the total water use in livestock production systems, water for livestock drinking is small in amount but is an important requirement for health and productivity of animals. This study was carried out to assess constraints and challenges of meeting drinking water requirements of livestock in rural mixed smallholder crop-livestock farming districts in the Ethiopian Rift Valley area. Data was collected by individual interviews with randomly selected respondents and farmer group discussions. Farmers ranked feed and water scarcity as the two most important constraints for livestock husbandry, although the ranking order differed between districts and villages. Poor quality water was a concern for the communities in proximity to urban settlements or industrial establishments. Water provision for livestock was challenging during the dry season, since alternative water sources dried up or were polluted. Though rainwater harvesting by dugout constructions was practiced to cope with water scarcity, farmers indicated that mismanagement of the harvested water was posing health risks on both livestock and people. A sustainable water provision for livestock in the area, thus, depends on use of different water sources (intermittent or perennial) that should be properly managed. Industrial establishments should adopt an environment-friendly production to minimize pollution of water resources used for livestock consumption. Technical support to farmers is required in proper design and use of existing rainwater harvesting systems. Further investigations are recommended on effect of poor quality water (perceived by farmers) on performance of livestock.

Bacterial contaminations of informally marketed raw milk in ghana

SUMMARY BACKGROUND

Milk has an outstanding nutritional quality but is also an excellent medium for bacterial growth and an important source of bacterial infection when consumed without pasteurization.

OBJECTIVE

To estimate the bacterial health risk of milk consumption in Accra and Kumasi, the two major cities in Ghana.

METHOD

A total of 96 raw milk samples collected in 2002 from the two sites were cultured and the isolated organisms identified by standard bacteriological methods.

RESULTS

Overall, the organisms identified and their prevalence rates were Yersinia spp. (19.8%), Klebsiella spp (16.7%), Proteus spp. (7.3%), Enterobacter spp. (6.3%), Escherichia coli (2.1%), and Staphylococcus spp (14.6%), Bacillus spp. (11.5%) and Mycobacterium spp. (1%). Most of the organisms identified were enterobacteria indicating probable faecal contamination of the milk as a result of poor hygiene. Most of the bacteria identified in the milk sampled are potential food-borne pathogens, and though some of them occurred in few samples, the practice of pooling milk from different sources by traders, and the absence of pasteurization generally observed among them could increase the risk posed by such organisms.

CONCLUSION

The study has shown that informally marketed raw milk in the two cities could be an important source of infection with a wide range of organisms, particularly enterobacteria. There is the need for instituting effective control measures including improved hygienic handling of milk and its pasteurization to protect public health.

Interference of raw milk autochthonous microbiota on the performance of conventional methodologies for Listeria monocytogenes and Salmonella spp. detection

Pathogen detection in foods by reliable methodologies is very important to guarantee microbiological safety. However, peculiar characteristics of certain foods, such as autochthonous microbiota, can directly influence pathogen development and detection. With the objective of verifying the performance of the official analytical methodologies for the isolation of Listeria monocytogenes and Salmonella in milk, different concentrations of these pathogens were inoculated in raw milk treatments with different levels of mesophilic aerobes, and then submitted to the traditional isolation procedures for the inoculated pathogens. Listeria monocytogenes was inoculated at the range of 0.2-5.2 log CFU/mL in treatments with 1.8-8.2 log CFU/mL. Salmonella Enteritidis was inoculated at 0.9-3.9 log CFU/mL in treatments with 3.0-8.2logCFU/mL. The results indicated that recovery was not possible or was more difficult in the treatments with high counts of mesophilic aerobes and low levels of the pathogens, indicating interference of raw milk autochthonous microbiota. This interference was more evident for L. monocytogenes, once the pathogen recovery was not possible in treatments with mesophilic aerobes up to 4.0 log CFU/mL and inoculum under 2.0 log CFU/mL. For S. Enteritidis the interference appeared to be more non-specific.

Listeria monocytogenes and Salmonella spp. in raw milk produced in Brazil: occurrence and interference of indigenous microbiota in their isolation and development

This study aimed to verify the occurrence of Listeria monocytogenes and Salmonella spp. in raw milk produced in Brazil. On account of the poor microbiological quality of this product, possible interference from the indigenous microbiota in these pathogens was also evaluated. Two-hundred and ten raw milk samples were collected in four important milk-producing areas in Brazil, tested for L. monocytogenes and Salmonella spp. presence, and for enumeration of indicator microorganisms: mesophilic aerobes, total coliforms and Escherichia coli. The interference of the indigenous microbiota in the isolation procedures was also tested, as well the frequency of naturally occurring raw milk strains with antagonistic activity against both pathogens. The pathogens were not isolated in any raw milk sample, but poor microbiological quality was confirmed by the high levels of indicator microorganisms. When present at high levels, the indigenous microbiota generated an evident interference in the methodologies of L. monocytogenes and Salmonella spp. isolation, mainly when the pathogens appeared at low levels. Three-hundred and sixty raw milk strains were tested for antagonistic activity against both pathogens, and 91 (25.3%) showed inhibitory activity against L. monocytogenes and 33 (9.2%) against Salmonella spp. The majority of the antagonistic strains were identified as Lactic Acid Bacteria species, mainly Lactococcus lactis subsp. lactis and Enterococcus faecium, known by antimicrobial substance production.