The usual routes of transmission of Streptococcus dysgalactiae in the development of bovine mastitis are unclear. For the control of mastitis in dairy practice, improved knowledge about the transmission of this pathogen would be very helpful. The variety of strain within a herd can be used to describe its transmission behavior. Isolates of Strep. dysgalactiae were collected from clinical mastitis samples on different farms, and the strains were typed using a molecular method. Overall, we performed strain typing on isolates from 16 farms in Germany and found signs of the contagious transmission of Strep. dysgalactiae on all the farms. We observed a variety of outcomes, from a single strain in all six Strep. dysgalactiae cases recorded on one farm, to five strains in six cases recorded on another farm. 

Die zytomikrobiologische Untersuchung von Viertelgemelksproben von Milchkühen ist eine in Deutschland weitverbreitete und bewährte Methode, um klinische und subklinische Mastitiden hinsichtlich des verursachenden Mastitiserregers und der somatischen Zellzahl zu analysieren. Zudem ist die Mastitisdiagnostik eine unverzichtbare Säule eines guten Eutergesundheitsmanagements. Die „Arbeitsgruppe Eutergesundheit“ der DVG-Fachgruppe Milchhygiene hat 2019 eine Vergleichsuntersuchung durchgeführt. Zweck der Untersuchung war es, Mastitislaboren die Möglichkeit zu geben, eine interne Qualitätskontrolle durchzuführen. Acht deutsche Mastitislabore haben an der Vergleichsuntersuchung teilgenommen. Die Proben wurden möglichst unbemerkt in die alltägliche Routinediagnostik der Labore eingeschleust. Die Vergleichsuntersuchung der vier Nativproben hat gute Übereinstimmungswerte hinsichtlich der zytomikrobiologischen Befunde und der Ergebnisse der Resistenzüberprüfungen zwischen den teilnehmenden Laboren ergeben. So lag beispielsweise die Übereinstimmung der teilnehmenden Labore in Bezug auf S. aureus sowie T. pyogenes bei 100 %. Bei Sc. uberis lag die Übereinstimmung bei 87,5 %. Nur eines der acht Labore wies hier „Nicht-aureus-Staphylokokken“ (NAS, ehemals KNS) aus. Die Ergebnisse der Untersuchung zeigen, dass die teilnehmenden Labore aufgrund des hohen Maßes an Standardisierung der Untersuchungsverfahren zuverlässige Ergebnisse liefern. Berücksichtigt werden muss jedoch, dass es sich um eine Vergleichsuntersuchung mit einer kleinen Probenzahl handelt und es einige Unterschiede hinsichtlich der diagnostischen Tiefe zwischen den Laboren gab. Mehr diagnostische Tiefe ist jedoch nur in dem Maße für den Praktiker von Nutzen, wie sich daraus praktische Maßnahmen ableiten lassen. Die diagnostischen Möglichkeiten übersteigen dabei häufig die Zahl differenzierter Maßnahmen bezüglich Mastitistherapie und -prävention.

The control of clinical mastitis on dairy farms is an essential part of animal health management. Knowledge of the causative microorganisms, the cure rates achievable in the field and essential associated factors are crucial for proper control. The objectives of the present study were to characterize clinical mastitis cases in Germany and to analyze factors influencing cure rates and the recurrence rate. Milk samples of every clinical mastitis case occurring on 12 participating farms were examined cytomicrobiologically. Post-treatment quarter samples were taken after 14 and 21 days. Treatments were performed according to existing farm protocols. Of 2883 clinical mastitis cases, the most prevalent pathogens were Streptococcus (S.) uberis (20.2%) and coliforms (11.6%). In 35% of the milk samples, no bacteriological growth was detected. The overall bacteriological cure rate was 73.3%, while the cytological cure rate was 22.3%, the full cure rate 21.4% and the recurrence rate 18.8%. Regarding the pathogen distribution of severe mastitis, coliform bacteria were detected in 30.5% of the cases, whereas S. uberis was detected in 26.5% thereof. The results show that severe mastitis is caused almost as frequently by Gram-positive as by Gram-negative microorganisms. The low cytological cure rates show that the therapy needs to be further developed with regard to calming the inflammation. The obtained data can be very helpful in assessing internal mastitis scenarios and the effect of measures and therapies.

Mastitis in dairy heifers during early lactation has global relevance and adverse impacts on milk production and milk quality. The aim of this study was to define the time-related period of intramammary infections and to relate this to risk factors for intramammary infections and subclinical mastitis by examining quarter milk samples of dairy heifers cytomicrobiologically. We worked out the important influence of early lactation on udder health and intramammary infections postpartum in dairy heifers. There is the possibility that udder quarters eliminate pathogens during early lactation, but there is also the danger that new infections manifest themselves. As related risk factors for new infections, the age at calving, udder edema, milk yield and somatic cell count after calving and detaching of milking cups during milking because of kicking off were determined. The prevention of new infections during the early lactation is an important purpose to ensure the future milk production and udder health in dairy heifers.

The antimicrobial activity of a phage mixture and a lactic acid bacterium against Staphylococcus aureus isolates from bovine origin was investigated in vitro with regard to possible applications in the therapy of udder inflammation (mastitis) caused by bacterial infections. The S. aureus isolates used for inoculation derived from quarter foremilk samples of mastitis cases. For the examination of the antimicrobial activity, the reduction of the S. aureus germ density was determined [log10 cfu/mL]. The phage mixture consisted of the three obligatory lytic and S. aureus-specific phages STA1.ST29, EB1.ST11 and EB1.ST27 (1:1:1). The selected Lactobacillus plantarum strain with proven antimicrobial properties and the phage mixture were tested against S. aureus in milk, both alone and in combination. The application of the lactic acid bacterium showed only a low reduction ability for a 24 h incubation period. The bacteriophage mixture as well as its combination with the lactic acid bacterium showed high antimicrobial activity against S. aureus for a 24 h incubation period at 37 ◦C, with only the phage mixture showing significance.

The aim of this research was to compare two sampling methods quantifying microbial load on teat ends, especially mastitis pathogens originating from the cows’ surroundings. Methods were compared using a split udder design, including 132 teat pairs in the study. For the first method, the wet/dry swab technique, a moistened swab was rotated 360° around the teat end, followed by a dry swab in the same manner. For the second and new method, the dipping technique, teat ends were immersed in a cup filled with Ringer’s solution and were removed after five seconds. Microbial load per milliliter as well as per teat end was calculated by determining the number of total aerobic mesophilic bacteria as well as environmental pathogenic bacteria, including coliform bacteria and esculin-positive streptococci. The concordance correlation coefficient (CCC) was used to quantify the agreement between two series of measurements and revealed the following coefficients: 0.112 for total aerobic mesophilic bacteria; 0.008 for coliform bacteria and 0.001 for esculin positive streptococci. The results of this study point out that under field conditions, the new method does not provide similar results when compared with the wet/dry swab technique for determining teat end microbial load.

The lytic efficacy of bacteriophages against Staphylococcus aureus isolates from bovine milk was investigated in vitro, regarding possible applications in the therapy of udder inflammation caused by bacterial infections (mastitis). The host range of sequenced, lytic bacteriophages was determined against a collection of 92 Staphylococcus (S.) aureus isolates. The isolates originated from quarter foremilk samples of clinical and subclinical mastitis cases. A spot test and a subsequent plaque assay were used to determine the phage host range. According to their host range, propagation and storage properties, three phages, STA1.ST29, EB1.ST11, and EB1.ST27, were selected for preparing a bacteriophage mixture (1:1:1), which was examined for its lytic activity against S. aureus in pasteurized and raw milk. It was found that almost two thirds of the isolates could be lysed by at least one of the tested phages. The bacteriophage mixture was able to reduce the S. aureus germ density in pasteurized milk and its reduction ability was maintained in raw milk, with only a moderate decrease compared to the results in pasteurized milk. The significant reduction ability of the phage mixture in raw milk promotes further in vivo investigation.

The present research study investigated the susceptibility of common mastitis pathogens—obtained from clinical mastitis cases on 58 Northern German dairy farms—to routinely used antimicrobials. The broth microdilution method was used for detecting the Minimal Inhibitory Concentration (MIC) of Streptococcus agalactiae (n=51), Streptococcus dysgalactiae (n=54), Streptococcus uberis (n = 50), Staphylococcus aureus (n = 85), non-aureus staphylococci (n = 88), Escherichia coli (n = 54) and Klebsiella species (n = 52). Streptococci and staphylococci were tested against cefquinome, cefoperazone, cephapirin, penicillin, oxacillin, cloxacillin, amoxicillin/clavulanic acid and cefalexin/kanamycin. Besides cefquinome and amoxicillin/clavulanic acid, Gram-negative pathogens were examined for their susceptibility to marbofloxacin and sulfamethoxazole/trimethoprim. The examined S. dysgalactiae isolates exhibited the comparatively lowest MICs. S. uberis and S. agalactiae were inhibited at higher amoxicillin/clavulanic acid and cephapirin concentration levels, whereas S. uberis isolates additionally exhibited elevated cefquinome MICs. Most Gram-positive mastitis pathogens were inhibited at higher cloxacillin than oxacillin concentrations. The MICs of Gram-negative pathogens were higher than previously reported, whereby 7.4%, 5.6% and 11.1% of E. coli isolates had MICs above the highest concentrations tested for cefquinome, marbofloxacin and sulfamethoxazole/trimethoprim, respectively. Individual isolates showed MICs at comparatively higher concentrations, leading to the hypothesis that a certain amount of mastitis pathogens on German dairy farms might be resistant to frequently used antimicrobials.

A non-blinded, positively controlled trial was conducted to evaluate the efficacy of an alternative, non-antibiotic therapy with Pyrogenium® to reduce ineffective antibiotic usage in the treatment of non-severe clinical mastitis (CM) in cows with longer lasting udder diseases. The solely treatment with Pyrogenium® (6 times, at a 12 hourly interval and then 4 times in a 24-hour interval) were compared with the reference treatment of solely local antibiotic therapy. The matched field study was conducted on five free-stall dairy farms located in Northern Germany. Cases of mild-to-moderate CM in cows with longer lasting high somatic cell counts in preceding dairy herd improvement test days and with previous CM cases in current lactation (chronic mastitis) were randomly allocated to one of the two treatment groups. A foremilk sample of the affected quarter was taken before treatment and again approximately 7 days, 14 days and 21 days after the end of therapy for cyto-bacteriological examination. Primary outcome was clinical cure (CC). Bacteriological cure (BC), quarter somatic cell count cure (CYC) and CM recurrence within 60 days after the end of treatment were chosen as secondary outcomes although low probabilities of bacteriological cure and quarter somatic cell count cure for selected cows were expected. The study resulted in the following findings: the pathogens mostly cultured from pretreatment samples were Staphylococcus aureus, followed by Streptococcus uberis. There were no significant differences between the test treatment (EG) in comparison with the reference treatment (CG) regarding all outcome variables (e.g. CC: EG 60.0%, CG 54.7%). Having regard to the selection criteria of cows in this study, the findings indicated that sole treatment with Pyrogenium® in non-severe CM cases may constitute an alternative therapy to reduce antibiotics.

The objective of this study was to gain information on udder health management and the use of antimicrobials in mastitis in dairy cows. The role of veterinarians in udder health management on dairy farms in Germany was a further focal point of this study. A total of 499 completed survey forms were returned by participating farms from nine federal states. Questionnaires revealed that the largest proportion of farms (32.1 %) were visited by their veterinarian on a weekly basis. The farm veterinarian was named most frequently as consultant for udder health (91.6%), followed by bovine health services (33.1%), agricultural consultants (27.5%) and other dairy professionals (20.0%). Fifty-eight percent of respondents had concise knowledge of parameters from the monthly udder health report submitted by the German Dairy Herd Improvement (DHI) organizations. Respondents from large farms (>500 cows) showed a significantly larger familiarity with udder health report contents than small farms (<100 cows) (p < 0.05). Clinical cases of mastitis were treated on all farms, although only 74.9% of participants reported immediate use of antimicrobials after diagnosis. Regular use of penicillin, other ß-lactam-antimicrobials, macrolids and lincomycin was reported by 356 participants (78.4 %) with 363 participants (80%) reporting additional or sole use of fluorchinolones or 3rd and 4th generation cephalosporines in mastitis therapy. Our results show that the farm veterinarian plays an integral role in mastitis management on German farms. A heavier focus should be directed at utilizing available udder health data for development of preventive and treatment protocols

The aim of this prevalence study was to describe the udder health situation at herd level of organic dairy herds in Northern Germany. Data from 21 voluntarily participating organic dairy herds (12-290 cows) were collected between 2011 and 2016, including somatic cell counts (SCC) from the dairy herd improvement test (DHI-test). Based on key figures from the DHI-test, the subclinical udder health status of each herd was described. Additionally, the incidence of clinical mastitis as well as the treatment of clinical mastitis cases and at drying off were obtained directly from farm records from questionnaires. On average, 45% of the cows in a herd were classified to be udder healthy during the study period. The average monthly new intramammary infection rate was 34% in the dry period and 27% during lactation at herd level. Half of the cows which had shown an elevated SCC (>100,000 cells/mL milk) at the last record before drying off were cured by the first DHI-test day after calving. For drying off, farm managers most commonly used internal teat sealants (44%), followed by antibiotic (22%) and homeopathic (5%) dry cow therapy wherein a combined treatment was possible. The average subclinical heifer mastitis rate was 36% at first record after calving. Additionally, 1.6% of the lactating cows had an incurable udder infection. The incidence of total clinical mastitis was 37 cases in 100 cow years under risk. The determined results were compared with those of conventional dairy herds published by other authors. Thus, this descriptive study demonstrated that the udder health in organic dairy herds is mainly comparable or tends to be worse than in conventional dairy herds, depending on individual parameters. In particular, the new infection rate during the dry period, the clinical mastitis rate as well as the heifer mastitis rate need to be improved.

The purpose of this investigation was to compare herd-level udder health regarding the extend of access to pasture and other management factors associated with pasturing and to determine pasture-associated risk factors. Data were provided by monthly dairy herd improvement test and collected over a period of 3 years and 4 months from 60 commercial dairy farms located in Lower Saxony, Germany. Farms were separated into 4 pasture groups depending on the extend of access to pasture of lactating cows. The proportion of udder-healthy animals of all lactating cows, the new infection rate of lactating cows and the heifer mastitis rate were derived from cow-level somatic cell counts and used as herd-level udder health indicators. Linear mixed models were applied. The udder health indicators were significantly associated with the time of year dry cows were given access to pasture indicating that dry cows should not be pasturing from October to March. Pasturing young livestock was beneficial if the animals were not younger than 3 months. The results of the research indicate that hygiene and management of dry cows and young livestock have a major influence on udder health of dairy cattle. The climatic and hygienic conditions during pasturing contribute to whether access to pasture has a positive or negative effect on the udder health.

Antibiotic resistance is a highly discussed issue in society. The use of antibiotics in livestock husbandry is critically viewed. As a result, the European commission issued guidelines for the prudent use of antimicrobial agents in veterinary medicine in 2015 (EU 2015/C 299/04). Thus, alternative approaches for treating cows in the future are necessary. In particular, the treatment of mastitis, the most frequent disease in the dairy industry, causes a high use of antibiotics. Implementing an on-farm test to assign mastitis pathogens to classes of pathogens (Gram-positive, Gram-negative, no bacterial growth) before treatment decisions are made provides the basis for an evidence-based mastitis therapy concept. Rapid Aerobic Count plates and Rapid Coliform Count plates of 3M™ Petrifilm™ (3M™ Neuss, Germany) were used in combination as a 12h rapid on-farm test concept. The diagnostic sensitivity and specificity were evaluated in comparison to the standard laboratory examination. 129 mastitis milk samples from the quarters with clinical mastitis by a conventional dairy farm in Germany were used for evaluation. Results were examined 12 hours after inoculating the Petrifilm™-plates. The sensitivity for Gram-positive pathogens was 93.2%. For Gram-negative pathogens it was 88.9%. The specificity was 39.0% for Gram-positive pathogens and 97.5% for Gram-negative pathogens, respectively. To get good results, training the milking personnel in taking aseptic milk samples as well as inoculating and evaluating the test is inevitable. On the basis of the results the 12h-Petrifilm™ concept can serve as a basis for treatment decisions in the evidence-based mastitis therapy in dairy herds with a low percentage of infections with eukaryotic pathogens and can complement bacteriological culture.

Pre-milking teat disinfection is practised in several countries to prevent environment-related mastitis. This study was designed to prove the antimicrobial efficacy of a foaming, iodine-based teat disinfectant with five different concentrations (250; 500; 1,000; 2,000 and 3,000 ppm) against a negative control. For this purpose the split-udder design was used and within an udder two teats were dipped with the test product before milking, while the other two teats were left untreated. After the customary udder preparation (pre-milking, cleaning of the teats with dry paper towel) the teat skin’s microbial load was investigated using the wet and dry swab technique. The total bacterial count, the counts of streptococci and streptococci like organisms (SSLO) and coliform bacteria were analysed. The associations between the treatment of the teats and the microbial load were analysed with a linear mixed regression model for repeated measurements. Microbial load with considered microorganisms was significantly lower on the skin of teats disinfected before milking compared to teats that were only cleaned. There are no differences in efficacy between the tested concentrations, e.g. the 250 ppm teat disinfectant was as effective as the 3000 ppm teat disinfectant.

Premilking cleaning and disinfection of teats were shown to be effective to prevent environmental mastitis. However, premilking teat disinfection is not a commonly used practice in Germany because of the risk of disinfection product residues in the milk. The objective of this study was to evaluate the effects of five differently concentrated iodine-based, foaming, premilking teat disinfectants on the iodine content of raw milk. The concentrations of the teat disinfectants were 250, 500, 1000, 2000 and 3000 ppm iodine. For each concentration five cows were treated and used for sample collection. Per udder two teats were dipped in the iodine disinfectant before milking; the other two teats were left untreated as a negative control (split-udder design). The contact time amounted to thirty seconds. Afterwards, all teats were cleaned with a dry paper towel. 15 mL milk from one treated and one untreated teat were manually milked into the test tubes before the milking cluster was attached. No significant differences in iodine concentration of the milk samples from the treated and the untreated teats were detected for all five disinfectant concentrations.

Intramammary infections from the prepartum period can affect udder health in the following lactation. The aim of this study was to investigate the effects of a polyurethane-based external teat sealer, which was applied on average 4.4 days before calving to primigravid animals and 2.8 days before calving to multigravid animals, on the development of udder health. In a split udder study, the teat canal orifices of the front left and the hind right udder quarter of clinical udder-healthy cows were sealed with the external teat sealer when first signs of approaching parturition were observed. Front right and hind left teats were left untreated. Aseptic quarter foremilk samples taken in week 1 and 2 after calving were investigated bacteriologically. Clinical mastitis in the first 100 days of lactation was recorded. In total, 130 primigravid and 93 multigravid cows were included into the study. In comparison to unsealed quarters (2.9% infected quarters), sealed quarters had twice as many intramammary infections (5.8%). The higher rate of intramammary infections in sealed quarters was mainly due to CNS (4.0% in sealed quarters, 2.5% in unsealed quarters). Based on random logistic regression models, the application of the external teat sealer was associated with increased odds of intramammary infections (P < 0.001), but not with clinical mastitis occurring in the first 100 days of lactation (P = 0.165). Further investigations are needed to characterize the dynamics of microbial populations under the external teat sealer.

In milk production, mastitis therapy accounts for the largest proportion of antibiotic use. Numerous studies have suggested that with a differentiated therapy based on mastitis causing pathogens and animal individual variables (regarding the number of lactation, somatic cell count (SCC) and the number of pre-treatments) the amount of antibiotics could be significantly lowered. The aim of this study was to investigate whether the establishment of an evidence-based mastitis therapy (EBMT) concept could reduce the amount of applied antibiotics compared to a conventional therapeutic (CT) approach with similar curing success. In the EBMT concept the therapy is tailored - with the additional help of on farm culture in the form of PetrifilmsTM - to the pathogen and to the patient and includes the latest scientific knowledge. In the CT approach the therapy is only tailored to the patient. The decision concerning therapy depends basically on the knowledge of the therapist and the severity of mastitis symptoms. To this end, from February until December 2012 all of the approximately 950 cows on a conventional dairy farm in Saxony-Anhalt, Germany, with clinical mastitis cases were assigned to an EBMT- (n = 236 cows) and a CT-group (n = 230 cows) based on the ear tag number and treated accordingly. Subsequently, the results of the two treatment groups were evaluated with respect to the clinical cure (CC), the bacteriological cure (BC), the full cure (FC), the relapse and culling rate and the amount of local and parenteral antibiotics used. Furthermore, the mean costs per clinical mastitis case of these two therapeutic concepts were compared. There was a significantly higher CC in the EBMT- versus the CT-group with simultaneous significant reduction in the local antibiotic doses without negative influence on the BC, FC, relapse and culling in the EBMT-group. Also, the mean costs per clinical mastitis case were significantly lower in the EBMT-group. This pilot study showed that by implementing on farm culture the use of an EBMT concept significantly reduces the use of local antibiotics in mastitis therapy without having any negative significant changes in the therapy outcome or economic aspects.

Udder quarters suffering from chronic and therapy-resistant infections represent a serious problem for dairy farms. Drying off such udder quarters during lactation would offer an opportunity to remove these single quarters from milk production without losing the whole milk yield of one cow during the current lactation. The use of a casein hydrolysate (CNH), an enzymatic fission product of casein, hence an endogenous substance, showed promising results regarding downregulation of milk secretion in udder quarters of high yielding dairy cattle in previous investigations in Israel. The objective of this study was to prove whether the infusion of CNH into the bovine mammary gland is an appropriate method to downregulate milk secretion in chronically infected udder quarters in high yielding dairy cows in Germany in order to dry off these single quarters without inducing clinical mastitis. Each treated udder quarter received six intracisternal infusions of CNH within 3 treatment days. After the last infusion of CNH on day 3, milking of the affected udder quarter was stopped. In 21 out of 24 (87.5 %) quarters a successful drying off could be achieved and only three quarters showed clinical mastitis. Furthermore, none of the animals showed a defence response or signs of pain during the intracisternal application. An increase in the average somatic cell score (SCS) during the treatment period could be revealed and 11 out of 16 conventionally milked quarters showed a decrease in milk yield. Hence, it could be shown that the infusion of CNH is an effective and gentle method for downregulating milk yield and drying off chronically infected and therapy-resistant single udder quarters during lactation.

Antibiotic therapy of clinical mastitis (CM) is difficult and often results in unsatisfactory outcomes. At detection of every CM case a reliable prognosis for the probability of bacteriological cure (BC) is beneficial to avoid useless application of antibiotic treatments. Therefore, factors which are associated with BC of CM have to be determined. A randomised, matched field study was conducted on 24 free-stall dairy farms located in Northern - and Central Germany. Data of CM cases receiving antibiotic treatment were recorded. A foremilk sample of the affected quarter was taken before treatment and again approximately 14 days and 21 days after the end of therapy for bacteriological examination. The BC of every CM case was determined. Animal-, pathogen-, treatment-, herd- and environment-related factors were added to every CM case and analysed statistically for associations with BC of the CM cases. The study resulted in the following findings: The overall BC rate was 74.6%. Cows with bacteriologically cured CM cases showed a lower somatic cell count, based on the seven Dairy Herd Improvement (DHI) test days before treatment (individual sum-200-7), and milk yield in the final DHI test before CM occurrence than cows with bacteriologically non-cured CM cases. The probability of BC decreased significantly if a cow had previously suffered from more than one CM case in current lactation. The likelihood of BC decreased significantly in CM cases where staphylococci were cultured in pre-treatment samples, especially due to the low BC rate of Staphylococcus aureus (46.7%), compared to CM cases caused by Enterobacteriaceae, streptococci or other pathogens. The probability of BC decreased with an increasing amount of the pathogen excreted pre-treatment.