The Streptococcus genus belongs to one of the major pathogen groups inducing bovine mastitis. In the dairy industry, mastitis is the most common and costly disease. It not only negatively impacts economic profit due to milk losses and therapy costs, but it is an important animal health and welfare issue as well. This review describes a classification, reservoirs, and frequencies of the most relevant Streptococcus species inducing bovine mastitis (S. agalactiae, S. dysgalactiae and S. uberis). Host and environmental factors influencing mastitis susceptibility and infection rates will be discussed, because it has been indicated that Streptococcus herd prevalence is much higher than mastitis rates. After infection, we report the sequence of cow immune reactions and differences in virulence factors of the main Streptococcus species. Different mastitis detection techniques together with possible conventional and alternative therapies are described. The standard approach treating streptococcal mastitis is the application of ß-lactam antibiotics. In streptococci, increased antimicrobial resistance rates were identified against enrofloxacin, tetracycline, and erythromycin. At the end, control and prevention measures will be considered, including vaccination, hygiene plan, and further interventions. It is the aim of this review to estimate the contribution and to provide detailed knowledge about the role of the Streptococcus genus in bovine mastitis.

Livestock manure is recycled to agricultural land as organic fertilizer. Due to the extensive usage of antibiotics in conventional animal farming, antibiotic-resistant bacteria are highly prevalent in feces and manure. The spread of wind-driven particulate matter (PM) with potentially associated harmful bacteria through manure application may pose a threat to environmental and human health. We studied whether PM was aerosolized during the application of solid and dried livestock manure and the functional relationship between PM release, manure dry matter content (DM), treatment and animal species. In parallel, manure and resulting PM were investigated for the survival of pathogenic and antibiotic-resistant bacterial species. The results showed that from manure with a higher DM smaller particles were generated and more PM was emitted. A positive correlation between manure DM and PM aerosolization rate was observed. There was a species-dependent critical dryness level (poultry: 60% DM, pig: 80% DM) where manure began to release PM into the environment. The maximum PM emission potentials were 1 and 3 kg t-1 of applied poultry and pig manure, respectively. Dried manure and resulting PM contained strongly reduced amounts of investigated pathogenic and antibiotic-resistant microorganisms compared to fresh samples. An optimal manure DM regarding low PM emissions and reduced pathogen viability was defined from our results, which was 55-70% DM for poultry manure and 75-85% DM for pig manure. The novel findings of this study increase our detailed understanding and basic knowledge on manure PM emissions and enable optimization of manure management, aiming a manure DM that reduces PM emissions and pathogenic release into the environment.

Along with industry and transportation, agriculture is one of the main sources of primary particulate matter (PM) emissions worldwide. Bioaerosol formation and PM release during livestock manure field application and the associated threats to environmental and human health are rarely investigated. In the temperate climate zone, field fertilization with manure seasonally contributes to local PM air pollution regularly twice per year (spring and autumn). Measurements in a wind tunnel, in the field and computational fluid dynamics (CFD) simulations were performed to analyze PM aerosolization during poultry manure application and the influence of manure moisture content and treatment. A positive correlation between manure dry matter content (DM) and PM release was observed. Therefore, treatments strongly increasing the DM of poultry manure should be avoided. However, high manure DM led to reduced microbial abundance and, therefore, to a lower risk of environmental pathogen dispersion. Considering the findings of PM and microbial measurements, the optimal poultry manure DM range for field fertilization was identified as 50-70%. Maximum PM10 concentrations of approx. 10 mg per m3 of air were measured during the spreading of dried manure (DM 80%), a concentration that is classified as strongly harmful. The modeling of PM aerosolization processes indicated a low health risk beyond a distance of 400 m from the manure application source. The detailed knowledge about PM aerosolization during manure field application was improved with this study, enabling manure management optimization for lower PM aerosolization and pathogenic release into the environment.

The regular use of antimicrobials in livestock production selects for antimicrobial resistance. The potential impact of this practice on human health needs to be studied in more detail, including the role of the environment for the persistence and transmission of antimicrobial‐resistant bacteria. During an investigation of a pig farm and its surroundings in Brandenburg, Germany, we detected abundant cephalosporin‐ and fluoroquinolone‐resistant Escherichia coli in pig faeces, sedimented dust, and house flies ( Musca domestica ). Genome sequencing of E. coli isolates revealed large phylogenetic diversity and plasmid‐borne extended‐spectrum beta lactamase (ESBL) genes CTX‐M‐1 in multiple strains. [Correction added on 28 February 2023, after first online publication: In the preceding sentence, ‘and TEM‐1’ was previously included but has been deleted in this version.] Close genomic relationships indicated frequent transmission of antimicrobial‐resistant E. coli between pigs from different herds and across buildings of the farm and suggested dust and flies as vectors for dissemination of faecal pathogens. Strikingly, we repeatedly recovered E. coli from flies collected up to 2 km away from the source, whose genome sequences were identical or closely related to those from pig faeces isolates, indicating the fly‐associated transport of diverse ESBL‐producing E. coli from the pig farm into urban habitation areas. The observed proximity of contaminated flies to human households poses a risk of transmission of antimicrobial‐resistant enteric pathogens from livestock to man.

Anaerobic digestion (AD) is a suitable process to use manure for biogas production. During this process, antimicrobial resistant (AMR) bacteria are reduced. In this study, we investigated the reduction of extended-spectrum beta-lactamase (ESBL)-producing, fluoroquinolone-resistant, and total Escherichia (E.) coli concentrations in chicken manure during AD. AD was performed at 30 °C and 37 °C (mesophilic temperature range), with and without sawdust addition as a lignocellulosic biomass. The initial concentrations of total E. coli were 6.43 log₁₀CFU/g to 7.84 log₁₀CFU/g. The concentration of Fluoroquinolone-resistant E. coli was approx. 6.05 log₁₀CFU/g (6.70%), and of ESBL-producing E. coli approx. 5.48 log₁₀CFU/g (0.99%). During AD, we observed that temperature had the main influence on the bacterial reduction, as E. coli abundance was below the detection limit after day 7 at 37 °C and after day 14 at 30 °C. At 37 °C we observed higher amounts of free ammonia, which is an inhibitor of the AD process. The carbon-to-nitrogen (C/N) ratio has an important impact on the AD process because a higher C/N ratio decreases the amount of generated total ammonia nitrogen. However, we did not observe a significant difference in AMR and total E. coli reduction between chicken manure with a natural C/N ratio (10:1) and an increased C/N ratio (25:1).

For fresh-cut salad production, hot-water treatment (HWT) needs optimization in terms of temperature and duration to guarantee a gentle and non-stressing processing to fully retain product quality besides an effective sanitation. One major initial target of heat treatment is photosynthesis, making it a suitable and sensitive marker for HWT effects. Chlorophyll fluorescence imaging (CFI) is a rapid and non-invasive tool to evaluate respective plant responses. Following practical applications in fruit salad production, apples of colored and of green-ripe cultivars (‘Braeburn’, ‘Fuji’, ‘Greenstar’, ‘Granny Smith’), obtained from a local fruit salad producer, were hot-water treated from 44 to 70 °C for 30 to 300 s. One day after HWT and after 7 days of storage at 4 °C, CFI and remission spectroscopy were applied to evaluating temperature effects on photosynthetic activity, on contents of fruit pigments (chlorophylls, anthocyanins), and on various relevant quality parameters of intact apples. In ‘Braeburn’ apples, short-term HWT at 55 °C for 30 to 120 s avoided any heat injuries and quality losses. The samples of the other three cultivars turned out to be less sensitive and may be short-term heat-treated at temperatures of up to 60 °C for the same time. CFI proved to be a rapid, sensitive, and effective tool for process optimization of apples, closely reflecting the cultivar- or batch-specificity of heat effects on produce photosynthesis.