Incidence rate, risk factors, and bacterial causes of clinical mastitis on dairy farms in Hawassa City, southern Ethiopia

Risk factors for dairy cows mastitis in Algeria, antibiotic resistance and molecular typing of the causative Staphylococcus aureus

Adoption of a rational management in dairy farms would improve the milk quality and farmers' income. In the current study, we aimed to describe bovine mastitis in 32 dairy herds, identify the main cow- and herd-associated risk factors, and analyze both epidemiological along with molecular characteristics of Staphylococcus aureus infecting udders. Based on Californian Mastitis Test and clinical examination, the prevalence of mastitis in cows was 52.25% (116/222), of which 6.3% was clinical mastitis and 45.94% was subclinical mastitis. Overall, 218 (24.54%) quarters suffered from mastitis, whose 29.81% (65/218) infected with S. aureus. Mastitis was lowest in mid-lactation with OR = 0.371 with 95% confidence interval (CI) of 0.141-0.976, and in cows separated from their calves (OR = 0.164, 95% CI 0.056-0.477) than suckler cows. Similar results were obtained from S. aureus related mastitis. To assess the genetic lineages of S. aureus isolates, we determined clonal complexes (CC) using DNA microarray hybridization profiles and performed spa typing. The strains were assigned to nine clonal complexes, and 19 spa types; with CC97 (44.77%), and CC22 (40.29%) were the most predominant lineages and t223 (40.29%), t7136 (10.44%), t359 (8.95%) and t267 (5.97%) were the most common spa types. A total of 88.05% (n = 59) isolates were resistant to at least one tested antibiotic while only 4.47% were multi-drug resistant strains. Higher rates of resistance were observed for penicillin (86.5%) and tetracycline (14.9%) respectively. Our results show the need for adoption of feasible mastitis program with special emphasis on sub-clinical mastitis and associated risk factors.

A Rapid and Inexpensive PCR Test for Mastitis Diagnosis Based on NGS Data

Mastitis is a common mammary gland disease of dairy cattle caused by a wide range of organisms including bacteria, fungi and algae. Mastitis contributes to economic losses of dairy farms due to reduced yield and poor quality of milk. Since the correct identification of pathogens responsible for the development of mastitis is crucial to the success of treatment, it is necessary to develop a quick and accurate test to distinguish the main pathogens causing this disease. In this paper, we describe the development of a test based on the multiplex polymerase chain reaction (PCR) method allowing for the identification of Streptococcus agalactiae, Streptococcus dysgalactiae, Streptococcus uberis and Staphylococcus aureus. When creating our test, we relied on the results from new generation sequencing (NGS) for accurate determination of species affiliation. The multiplex PCR test was verified on 100 strains including veterinary samples, ATCC and Polish Collection of Microorganisms (PCM) reference strains. The obtained results indicate that this test is accurate and displays high specificity. It may serve as a valuable molecular tool for the detection of major mastitis pathogens.

Pre-Harvest Food Safety Challenges in Food-Animal Production in Low- and Middle-Income Countries

Food safety remains a significant global public health concern, with the risk of unsafe food varying worldwide. The economies of several low- and middle-income countries (LMICs) heavily rely on livestock, posing a challenge to ensuring the production of safe food. This review discusses our understanding of pre-harvest critical issues related to food safety in LMICs, specifically focusing on animal-derived food. In LMICs, food safety regulations are weak and inadequately enforced, primarily concentrating on the formal market despite a substantial portion of the food sector being dominated by informal markets. Key critical issues at the farm level include animal health, a low level of good agriculture practices, and the misuse of antimicrobials. Effectively addressing foodborne diseases requires a comprehensive One Health framework. Unfortunately, the application of the One Health approach to tackle food safety issues is notably limited in LMICs. In conclusion, considering that most animal-source foods from LMICs are marketed through informal channels, food safety legislation and policies need to account for this context. Interventions aimed at reducing foodborne bacterial pathogens at the farm level should be scalable, and there should be strong advocacy for the proper implementation of pre-harvest interventions through a One Health approach.

Isolation of bacteriophages specific to bovine mastitis-causing bacteria and characterization of their lytic activity in pasteurized milk

Background and Aim

Bovine mastitis is one of the most serious issues in dairy production. It is caused by contagious and coliform pathogens such as Staphylococcus spp., Escherichia coli, and Klebsiella pneumoniae. In addition, the emergence of drug-resistant bacteria raises urgent concerns in the field of drug treatment, thus requiring the exploration of alternative treatments. Bacteriophage therapy has been shown to be a promising alternative approach for the control of antibiotic-resistant pathogens. In this study, we aimed to isolate phages specific to contagious mastitis and coliform mastitis, characterize the isolated phages, and examine their ability to lyse bacteria in pasteurized milk samples.

Materials and Methods

The Staphylococcus phage vB_Sau-RP15 isolated from raw milk in our previous study was used in this study. Other three phages, vB_Eco-RN12i1, vB_Kpn-RN14i1, and vB_Ssc-RN20i3, were isolated from wastewater using E. coli 5823, K. pneumoniae 194, and Staphylococcus sciuri MM01 as hosts, respectively. The host range and efficiency of plating (EOP) were determined following phage isolation. Moreover, the lysis activities of these phages against their hosts were investigated in pasteurized milk using a multiplicity of infections (MOIs) of 10 and 100 at 37°C. Phages were applied using individual and combination phages.

Results

According to the EOP results, all phages showed high specificity to their respective hosts. They are tailed phages with distinct morphologies. Individual phage treatments in spiked pasteurized milk with their respective bacterial hosts significantly reduced the bacterial counts in both MOI conditions during the first 2 h of the treatment (approximately 1-8 log reduction compared to the control). Although these phages specifically infected only their hosts, the phage cocktail resulted in a better result compared to the use of individual phage. However, bacterial regrowth was observed in all experiments, which may be related to the development of phage-insensitive mutants.

Conclusion

Our findings suggest that the application of phages could be used to treat bovine mastitis. Phage cocktail is suitable to promote the efficacy of phage treatment in pasteurized milk. However, when considering the use of phages in dairy cows, certain phage properties in raw milk and in vivo and ex vivo should be highlighted to ensure their effectiveness as biocontrol agents for bovine mastitis treatment.