Clinical Mastitis Cases Research Articles

In vitro capsule or biofilm formation of Streptococcus uberis and bacteriological cure of bovine mastitis.

The relationship between the in vitro detected virulence factors biofilm and capsule formation of Streptococcus (S.) uberis isolates of clinical mastitis in dairy cows and the bacteriological cure rate after antibiotic therapy was investigated in order to better understand the importance of these virulence factors for the bacteriological cure rate. A total of 111 clinical mastitis (CM) cases were collected, in which S. uberis was bacteriologically detected. All mastitis cases were treated in accordance with the approval conditions of the antibiotic udder tubes used. Individual cow information including age, number of lactations, current lactation mastitis and antimicrobial treatment received was recorded. The microtiter plate test was used to detect biofilm formation and Anthony capsule staining was used to detect capsular capacity. Statistical analyses were performed to characterize the correlation between in vitro virulence factors and bacteriological cure (BC) rate. 30.5% (n=29) of the S. uberis isolates of bacteriologically cured cases and 34.5% (n=10) of the isolates of bacteriologically non-cured mastitis cases were found to have the ability to produce capsules in vitro. 70.7% (n=58) of the S. uberis isolates from bacteriologically cured mastitis cases had the ability to produce biofilm in vitro, whereas 58.6% (n=17) of the isolates of non-cured mastitis cases showed ability in producing biofilm. No correlation was found between the in vitro ability of S. uberis to form capsules and biofilms and the BC rate after antibiotic treatment of bovine mastitis. The present work has shown that the investigated in vitro virulence factors are not associated with the BC after antibiotic therapy. Further studies on the role of S. uberis virulence factors are needed to complete the missing knowledge on the difficulties in curing S. uberis mastitis. This study is of great clinical relevance since it enhances the understanding of the occurrence of BC in S. uberis mastitis cases. The investigated virulence factors are often addressed as possible reasons for therapy failure, although respective scientific studies are missing.

Eficiência do produto homeopático BioBoi® combinado ao manejo adequado da ordenha, no tratamento de mastite em vacas em lactação

The dairy production chain is one of the main economic activities in Brazil, with primary production present in almost all Brazilian municipalities, involving more than one million rural producers, and generating jobs in all segments of the chain. The growing consumption of dairy products, and the pursuit of quality, lead to increasing concern with food and nutritional safety. Among the factors that affect milk composition are management and the incidence of diseases, with mastitis being one of the most frequent infections affecting dairy cattle. This results in economic losses due to reduced production and milk quality, increased costs for labor, medication, and veterinary services, and the early disposal of animals. Treatment with commercial homeopathic products presents an alternative to avoid problems found in the continuous use of allopathic medicines, such as residues in animal-derived products, selection of multi-resistant strains, and reactions in hypersensitive individuals. The general objective of this study was to evaluate the efficiency and effectiveness of using a commercial homeopathic product in the treatment of bovine mastitis when combined with proper milking management. Our specific objectives were to evaluate the milker’s handling before, during, and after milking, to determine the incidence and prevalence of clinical and subclinical cases of mastitis in the herd before and after treatment, and to perform comparative analyses of the data obtained at the beginning and end of the experiment. The results showed that positive behaviors by the milker had greater influence on the cows' behavior, which remained calm and stress-free throughout the milking process, as well as a correlation with obtaining low somatic cell counts (SCC). Regarding the prevalence of mastitis in the herd, although it decreased, there was no statistically significant difference. However, there was evidence of the positive interference of the homeopathic medicine on its incidence. It is concluded that the homeopathic medicine is effective in inhibiting the emergence of new cases of mastitis, as well as in treating acute cases of mastitis and reducing the herd's SCC, being efficient in the control and prevention of mastitis; it is also concluded that the milker plays an important role in this process, making it essential for them to be aware and valued for this.

Comparison of a machine learning model with a conventional rule-based selective dry cow therapy algorithm for detection of intramammary infections

We trained machine learning models to identify intramammary infections (IMI) in late lactation cows at dry-off to guide antibiotic treatment, and compared their performance to a rule-based algorithm that is currently used on dairy farms in the US. We conducted an observational test-characteristics study using a data set of 3,645 cows approaching dry-off from 68 US dairy herds. The outcome variables of interest were cow-level IMI caused by all pathogens, major pathogens, and Streptococcus and Strep-like organisms (SSLO), which were determined using aerobic culture of aseptic quarter-milk samples and identification of isolates using MALDI-TOF. Individual cow records were extracted from the farm software to create 53 feature variables at the cow and 39 at the herd-level which were derived from cow-level descriptive data, records of clinical mastitis events, results from routine testing of milk for volume and concentrations of somatic cell count (SCC), fat, and protein. ML algorithms evaluated were logistic regression, decision tree, random forest, light gradient-boosting machine, naïve bayes, and neural networks. For comparison, cows were also classified according to a conventional rule-based algorithm that considered a cow as high risk for IMI if she had at one or more high SCC (>200,000 cells/ml) tests or ≥2 cases of clinical mastitis during the lactation of enrollment. Area under the curve (AUC) and Youden's index were used to compare models, in addition to binary classification metrics, including sensitivity, specificity, and predictive values. ML models had slightly higher AUC and Youden's index values than the rule-based algorithm for all IMI outcomes of interest. However, these improvements in prediction accuracy were substantially less than what we had considered necessary for the technology to be a worthwhile alternative to the rule-based algorithm. Therefore, evidence is lacking to support the wholesale use of ML-guided selective dry cow therapy at the moment. We recommend that producers wanting to implement algorithm-guided SDCT use a rule-based method.

Unravelling the complex mechanisms of multidrug resistance in bovine mastitis pathogens: Insights into antimicrobial resistance genes, biofilm dynamics, and efflux systems

Mastitis remains a paramount economic threat to dairy livestock, with antibiotic resistance severely compromising treatment efficacy. This study provides an in-depth investigation into the multidrug resistance (MDR) mechanisms in bacterial isolates from bovine mastitis, emphasizing the roles of antimicrobial resistance genes (ARGs), biofilm formation, and active efflux systems. A total of 162 Staphylococci, eight Escherichia coli, and seven Klebsiella spp. isolates were obtained from 215 milk samples of clinical and subclinical mastitis cases. Antibiotic susceptibility testing identified Twenty Staphylococci (12.35 %), six E. coli (75 %) and seven Klebsiella (100 %) identified as MDR displaying significant resistance to β-lactams and tetracyclines The Multiple Antibiotic Resistance (MAR) index of these isolates ranged from 0.375 to 1.0, highlighting extensive resistance. Notably, 29 of the 33 MDR isolates produced biofilms on Congo red agar, while all exhibited biofilm formation in the Microtitre Plate assay. Critical ARGs (blaZ, blaTEM, blaCTX-M, tetM, tetA, tetB, tetC, strA/B, aadA) and efflux pump genes (acrB, acrE, acrF, emrB, norB) regulating active efflux were identified. This pioneering study elucidates the synergistic contribution of ARGs, biofilm production, and efflux pump activity to MDR in bovine mastitis pathogens. To our knowledge, this comprehensive study is the first of its kind, offering novel insights into the complex resistance mechanisms. The findings underscore the imperative need for advanced antibiotic stewardship and strategic interventions in dairy farming to curb the rise of antibiotic-resistant infections, thereby protecting both animal and public health.

Green synthesized silver nanoparticles from Ocimum sanctum: A potent inhibitor of biofilm forming ability and efflux pumps in bacteria causing bovine mastitis

Therapeutic management of mastitis faces significant challenges due to multidrug resistance. In the present study, multi-drug-resistant (MDR) Staphylococcus spp, Klebsiella pneumoniae, and Escherichia coli were isolated from bovine clinical mastitis cases and the phenotypic and genotypic multidrug resistance profiling was carried out. Silver nanoparticles (AgNPs) were biosynthesized using Ocimum sanctum leaf extracts and characterized via UV Vis absorption, Fourier Transform Infrared Spectroscopy, X-ray diffraction studies, Energy dispersive spectroscopy and Electron Microscopy. The determined minimum inhibitory concentration and minimum bactericidal concentration of the AgNPs against the recovered MDR isolates were 62.5 μg/ml and 125 μg/ml respectively. At a concentration of 50 μg/ml, the AgNPs demonstrated biofilm inhibitory activities of 80.35 % for MDR E. coli, 71.29 % for S. aureus and 60.18 % for MDR K. pneumoniae. Post-treatment observations revealed notable differences in biofilm formation across bacterial isolates. Furthermore, AgNP treatment led to significant downregulation of expression of the efflux pump genes acrB, acrE, acrF, and emrB in Gram-negative isolates and norB in Staphylococci isolates. This research underscores the potential for the development of an eco-friendly antimicrobial alternative in the form of green synthesized silver nanoparticles to combat drug resistance offering potential antibiofilm and efflux pump inhibitory activities.

Advancing mastitis assessment in dairy bovines via short milking tube thermography: A seasonal perspective.

In India, where dairy production leads globally, infrared thermography (IRT) and short milking tube thermography specifically are vital for managing mastitis. Therefore, the present study focuses on thermal imaging of the udder and short milking tube (SMT) of the milking machine during the peak milking process of Sahiwal cows and Murrah buffaloes during winter, summer, rainy and autumn seasons to identify sub-clinical (SCM) and clinical mastitis (CM) cases using the Darvi DTL007 camera. The udder health was assessed using the California Mastitis Test, Somatic Cell Count (SCC) and IRT throughout the year. Log10SCC and thermogram analysis revealed a difference (p < 0.01) between healthy, SCM, and CM cases during different seasons in both breeds. Further results showed an increase (p < 0.01) in SMT thermograms of SCM and CM cases compared to healthy quarters in Sahiwal cows during winter, summer, rainy, and autumn were 4.26 and 7.51, 2.37 and 4.47, 2.20 and 3.64, 2.90 and 4.94 ºC, respectively and for Murrah buffaloes were 3.56 and 5.55, 2.70 and 3.81, 1.72 and 3.10, 3.14 and 4.42ºC, respectively. The highest degree of increase in milking udder skin surface temperature and SMT of SCM and CM cases compared to healthy quarters was observed during the winter and the least during the rainy season. Thus, regardless of the seasons examined in this study, SMT thermograms effectively assessed SCM and CM.

Seasonal assessment of mastitis in crossbred goats: A thermographic approach

Sub-clinical mastitis exhibits a higher prevalence in dairy goats than clinical mastitis, necessitating the adoption of non-invasive diagnostic techniques such as infrared thermography (IRT) to detect this economically significant production disease in the dairy sector. Accordingly, this study aims to employ IR imaging of the udder and teat quarters of lactating crossbred goats (Alpine × Beetal and Sanen × Beetal) across various seasons, utilising IRT, to discern cases of sub-clinical (SCM) and clinical mastitis (CM). Over a year, 100–110 lactating crossbred dairy goats underwent consistent IRT screenings, followed by a comprehensive evaluation of udder health status using the California mastitis test and somatic cell count (SCC). The receiver operating characteristic (ROC) analysis was conducted to establish the cut-off values for different thermographic parameters in this study. The results revealed that the SCC increased significantly (p < 0.01) in healthy, SCM, and CM milk samples across the seasons. The analysis of ROC revealed a comparatively higher sensitivity, specificity, and accuracy for udder thermograms during SCM than CM and vice versa for teat thermograms. IRT analysis reflected a difference (p < 0.01) in the udder and teat thermograms among quarters of healthy, SCM, and CM in summer, winter, autumn, and rainy seasons. A significant increase (p < 0.01) in udder thermograms was observed for quarters affected with SCM and CM relative to healthy, with an increase of 1.89 and 2.94 °C in winter, 0.85 and 1.63 °C in summer, 0.73 and 1.41 °C in rainy, and 1.33 and 2.38 °C in autumn, respectively. Similarly, for teat thermograms it was 1.79 and 2.81 °C in winter, 0.76 and 1.41 °C in summer, 0.70 and 1.37 °C in rainy, and 1.09 and 1.93 °C in autumn, respectively. Therefore, regardless of the seasons examined in this study, IRT proves to be an effective and supportive tool for early mastitis detection in lactating crossbred dairy goats.

Trueperella Pyogenes-Strain Diversity and Occurrence in Dairy Herds.

Trueperella (T.) pyogenes is a mastitis-causing pathogen formerly known to cause severe clinical mastitis (CM), especially during the summer, leading to milk losses and low recovery rates. Unfortunately, its transmission behavior within herds is unclear. The diversity and occurrence of T. pyogenes were monitored to gain an initial insight into the infection transmission behavior of T. pyogenes in dairy herds and to lay a foundation for following targeted investigations. CM milk samples were collected from German herds, and one Swedish farm was sampled for isolates from subclinical mastitis. All in all, 151 T. pyogenes isolates from 16 herds were isolated, identified by MALDI TOF analysis and typed with RAPD PCR. Of these, 17 isolates originated from subclinical mastitis cases. We found that T. pyogenes mastitis occurred year-round, and clinical mastitis cases were caused by multiple strains (31 affected animals/28 strains). Instances of multiple cows being infected with the same T. pyogenes strain were rare and typically only involved a small number of animals at a time. However, if several quarters of a cow were affected, it was likely the same strain. Unlike clinical infections, subclinical T. pyogenes infections, in one investigated farm, harbored a dominant strain. Additionally, we found that T. pyogenes infections tended to persist and stay within a herd for a minimum of 7 months in the same or different cows.

Studi Kasus: Terapi Mastitis Klinis pada Sapi Perah di Kota Batu

The purpose of this case report is to report a case of clinical mastitis in dairy cattle in Batu. One case was reported on this period. Anamnesis was carried out, the owner revealed that the cow did not produce milk and when milking the udderand nipples felt hard and the milk that wanted to come out seemed to be stuck. Physical examination was carried out, cow’s weight ±400 kg, body temperature 38.4 °C, the udder and nipple were swollen and inflamed, and decrease of milk production, mammae showed reddish and asymmetrical and painful when palpate. Based on the history and physical examination of the cow, it can be concluded that the cow was diagnosed with clinical mastitis with a fausta prognosis and the differential diagnosis was mammary tumour. The therapy given in this case was injection of the antibioticInterspectin-L® 10 ml, the anti-inflammatory and antipyretic Tolfedine® 10 ml intramuscularly.

Prevalence and Molecular Characteristics of Enterococci Isolated from Clinical Bovine Mastitis Cases in Ningxia [Letter]

Prevalence and Molecular Characteristics of Enterococci Isolated from Clinical Bovine Mastitis Cases in Ningxia [Letter]

Antimicrobial Susceptibility in Clinical Mastitis Cases on Simmental Farms in the Mačva Region (Serbia)

Antimicrobial Susceptibility in Clinical Mastitis Cases on Simmental Farms in the Mačva Region (Serbia)

The effect of selective dry cow therapies based on 2 different algorithms on antimicrobial use, udder health, milk production, and culling in the absence of internal teat sealant use at dry-off

The objective of this study was to evaluate the effect of selective dry cow therapy (SDCT) strategies based on 2 different algorithms as compared with blanket dry-cow therapy for measures of udder health, milk yield, and culling in herds not using internal teat sealant. Cows from 2 commercial farms in West Texas were randomized into 3 different groups: SDCT Algorithm 1 (ALG1; n = 455) cows treated with an intramammary antimicrobial at dry-off if somatic cell count (SCC) > 200,000 cells/mL at any Dairy Herd Improvement Association (DHIA) test date or if the cow had 2 or more cases of clinical mastitis during the enrollment lactation; SDCT Algorithm 2 (ALG2; n = 458) cows treated with an intramammary antimicrobial at dry-off if SCC >200,000 cell/mL at last test date or any case of clinical mastitis during the enrollment lactation; Control cows (CON = 447) received blanket dry cow therapy. All cows enrolled in the study did not receive an internal or external teat sealant. Data related to milk and somatic cell count linear score (LSCC) was collected monthly. Milk yield and LSCC during the first 6 mo of lactation were analyzed using repeated measures ANOVA models, while Cox's Proportional Hazards models were fitted to culling and clinical mastitis data. The farm was fitted as a random effect in all models. The percentage of cows receiving antimicrobials at dry cow was 51.3, 24.7, and 100% for ALG1, ALG2, and CON, respectively. Treatment did not influence the IMI dynamics during the dry period. Additionally, no statistical differences related to treatment were observed for LSCC and milk yield. The LSCC for ALG1, ALG2, and CON was 2.44, 2.41, and 2.26, respectively. The average milk yield for ALG1, ALG2, and CON cows was 43.2, 43.2, and 44.0 kg/d, respectively. Treatment did not affect clinical mastitis incidence and culling. The cumulative incidence of clinical mastitis was 19.6%, 19.4%, and 21.4% for ALG1, ALG2, and CON cows respectively. Additionally, the cumulative risk of death or culling was 18.5%, 17.1%, and 19.5% for ALG1, ALG2, and CON cows respectively. In conclusion, SDCT strategies led to a decrease in antimicrobial drug use at dry-off, without significantly impacting the incidence of clinical mastitis, the risk of culling, LSCC and milk yield of dairy cows. However, numerical differences in LSCC and milk yield were observed between treatment groups.

An observational study of farmer-reported clinical mastitis in New Zealand dairy ewes

ABSTRACT Aims To describe the incidence, aetiology, treatment, and outcomes of farmer-reported clinical mastitis on New Zealand dairy sheep farms. Methods A prospective cohort study was conducted on 20 spring-lambing New Zealand sheep milking farms over the 2022–2023 season. Clinical mastitis was defined as a change in the appearance of milk and/or signs of inflammation in the gland. Farmers were required to report all cases of clinical mastitis and collect information on affected ewes’ demographics, clinical features, treatments (where applicable), and outcomes. Milk samples from mastitic glands were submitted for microbiological culture and identification by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF). Results Partial or complete clinical mastitis data were available for 236 cases from 221 ewes on 18/20 study farms. Clinical mastitis was diagnosed in 0–6% of ewes at the farm level, with an overall incidence of 1.8 (95% CI = 1.0–3.2)% using the study data, or 2.3 (95% CI = 1.6–3.3)% using the study data and farmer estimates that included unreported cases. Cases occurred mostly in early lactation, with 59% detected during the lambing period (August–October), at a median of 7 (IQR 3, 40) days in milk. The majority of cases featured clots in the milk (59%), swelling (55%), and unevenness (71%) of the glands. Pyrexia (rectal temperature ≥ 40.0°C) was diagnosed in 25% of cases and depression (lethargy, inappetence, or inability to stand) in 26% of cases. Treatment was given to 46% of cases, with tylosin being the most commonly used treatment (50% of treated cases). The most common outcome was immediate drying off to be culled without treatment (32%), followed by still milking and recovered but with lasting problems (25%). Nearly half of all the milk samples submitted were culture negative. Streptococcus uberis (14%), non-aureus staphylococci (12%), and Staphylococcus aureus (11%) were the most common isolates, found on 12, 8 and 8 of the 16 farms with microbiological data, respectively. Conclusions Clinical mastitis affected up to 6% of ewes at the farm level. Systemic signs were observed in one quarter of affected ewes, suggesting a role for supportive treatment. Clinical mastitis can be severe and challenging to fully resolve in New Zealand dairy sheep. Clinical relevance This is the first systematic study of clinical mastitis in New Zealand dairy ewes. It provides baseline information specific to New Zealand conditions for farmers, veterinarians, and other advisors to guide the management of mastitis for the relatively new dairy sheep industry in New Zealand.

Confirmed bacteriological diagnosis and cure of non-severe Gram-positive clinical mastitis cases enrolled in a randomized clinical trial based on results of on-farm culture

Our objectives were to describe the confirmed bacteriological diagnosis of mastitis pathogens cultured from cases of non-severe clinical mastitis (CM) identified as Gram-positive (GP) using on-farm culture and to compare differences in bacteriological cure (BC) based on antimicrobial (AM) therapy. Cows that developed non-severe CM in a single quarter were enrolled in a randomized clinical trial based on microbial growth on GP selective agars. Cows were randomly assigned to receive a once-daily intramammary treatment: 3d hetacillin (n = 69), 3d ceftiofur (n = 69), 8d ceftiofur (n = 70) or to a non-treated group (n = 32). Etiologies were confirmed with MALDI-TOF using frozen duplicate milk samples. The crude proportion of BC was determined using milk samples collected at 14, 21 and 28 d after enrollment for cases caused by Streptococci, non-aureus staphylococci (NAS), Strep-like organisms (consisting of Enterococcus and Lactococcus.; SLO) and Staph. aureus. Multivariable models were used to determine the effect of AM treatment on BC cure at d 21 for a subset of cases that had complete data for all covariates (n = 88). Growth on GP agar resulted in enrollment of 240 cases with confirmed etiologies distributed as Strep. spp (21.7%; n = 52), Lact. spp (19.2%; n = 46), NAS (16.3%; n = 39), Staph aureus (6.3%; n = 16), Entero spp (5.0%; n = 12) and others (10%; n = 24). Thirty-five (14.5%) duplicate milk samples collected from enrolled cows had no significant growth in the lab while 16 (6.7%) were contaminated. Among sampling dates, combined crude BC for cases caused by target pathogens ranged from 68 to 71%. Crude BC ranged from 58 to 73% for the small group of non-treated cases (n = 12) and 69–71% for the combined group of cases that received IMM AM (n = 113). Among all groups and all follow-up dates, crude BC was least for cases caused by Staph. aureus (ranging from 33 to 43%), followed by cases caused by SLO (58–67%), NAS (79–80%) and Strep. spp. (81–91%). The proportion of BC at 21d (LSM ± SE) did not vary between all cases that received AM (0.77 ± 0.06) and cases in the non-treated group (0.73 ± 0.16). The odds of BC at 21d was about 5x greater for cases that occurred in primiparous as compared with multiparous cows and decreased 1.3-fold for each 1 log unit increase in SCC before the case. While this study does not have sufficient power to detect small differences in BC among pathogen groups or treatments, our results demonstrate that CM is caused by a wide diversity of GP bacteria with varying ranges of BC. These results provide justification for inclusion of negative control groups in future studies and confirm that important characteristics such as parity and history of subclinical mastitis influence the probability of BC.

Molecular Characterization of Resistance and Virulence Factors of Trueperella pyogenes Isolated from Clinical Bovine Mastitis Cases in China.

The present study was designed to investigate the resistance determinants and virulence factors of 45 Trueperella pyogenes isolates from clinical bovine mastitis in Hexi Corridor of Gansu, China. Minimum inhibitory concentrations (MICs) was tested by E-test method. Gene of antimicrobial resistance, virulence integrase and integron gene cassettes were determined by PCR and DNA sequencing. The T. pyogenes isolates exhibited high resistance to streptomycin (88.9%) and tetracycline (64.4%), followed by erythromycin (15.6%) and gentamicin (13.3%). Resistance to streptomycin was most commonly encoded by aadA9 (88.9%); and to tetracycline, by tetW (64.4%). Importantly, all streptomycin-resistant isolates carried aadA9 alone or in combination with aadA1, aadA11 and strA-strB. Similarly, all tetracycline-resistant isolates harbored tetW alone or in combination with tetA33. Meanwhile, ermX was detected in 13.3% isolates, only one erythromycin-resistant isolate was not identified for this gene. Moreover, all T. pyogenes isolates carried class 1 integrons, and 17.8% of them contained gene cassettes, including arrays aadA1-aadB (4.4%), aad A24-dfrA1-ORF1 (2.2%) and aadA1 (2.2%). Furthermore, all tested isolates harbored virulent genes plo and fimA, followed by fimC (88.9%), fimE (86.6%) nanP (75.6%), nanH (40.0%), cbpA (35.6%) and fimG (6.7%). To our knowledge, this is the first report of integron gene cassettes of T. pyogenes isolates from bovine mastitis cases in China. These findings are useful for developing the prevention and the virulence factors of T. pyogenes could be promising candidates for vaccine antigens for bovine mastitis caused by T. pyogenes in China.

A Temporal Study on Incidence of Bovine Mastitis in Haryana, India

Mastitis affects dairy animal’s productivity and causes financial losses for dairy farmers in India and across the world. In this study, a total of 52,494 quarter milk samples from 14,381 bovines were screened for the primary microorganisms causing mastitis in Hisar and adjoining districts of Haryana and their antibiotic sensitivity patterns were analyzed. The cultural positivity from subclinical form of mastitis was observed as 86.32% and 87.73% from cows and buffaloes, respectively while that from clinical mastitis was 87.36% and 87.57%. The major Gram positive bacterial pathogens associated with mastitis in the entire study period were found as Staphylococcus species with an average incidence rate of 45.53% and 44.1% from cows and buffaloes, respectively. The Streptococcus species were found to be 33.76% and 29.94% of total isolates. Escherichia coli were the most predominant Gram negative bacteria isolated (17.37% and 13.85%), thereafter Klebsiella spp. (5.54% and 5.19%) from both cows and buffaloes. A significant proportion of clinical cases of mastitis were chronic in nature from both the species of bovines. The incidence of mastitis with respect to different lactation number and lactation months was found as significant. The highest incidences of mastitis was observed in the first lactation among buffaloes (20.69%), while the maximum incidences were observed in second and third lactation in cows with 16.59% and 16.99%, respectively. However, in both the species maximum occurrence of mastitis was observed during the first lactational month. The antibiotic sensitivity patterns of most of the isolates had shown higher sensitivity towards enrofloxacin and gentamicin, while the penicillin had shown least sensitivity. The knowledge regarding the mastitis causing pathogens and their sensitivity pattern in Hisar and adjoining districts of Haryana enables the veterinarians to adopt for the proper treatment protocols and dairy farmers to assure optimal health, welfare and productivity of bovines in the State, in turn reducing antimicrobial resistance.

Virulence and antimicrobial resistance genes detected in Staphylococcus spp. isolated from clinical and non-clinical mastitis using whole-genome sequencing

Staphylococcus spp. are among the most isolated bacteria in clinical and subclinical mastitis cases in dairy cattle. The genus comprises biofilm-forming bacteria capable of producing toxins and acquiring resistance to multiple drugs. This work aimed to evaluate the genetic profile related to virulence and antimicrobial resistance characteristics of Staphylococcus spp., isolated from clinical mastitis and non-clinical fresh cows using whole genome sequencing (WGS). The bacterial collection consisted of 29 Staphylococcus strains isolated from clinical cases of mastitis (n = 7), as well as milk samples collected from fresh cows (n = 22). Strains were identified as Staphylococcus aureus (n = 2), Staphylococcus chromogenes (n = 19), and Staphylococcus haemolyticus (n = 8). A total of 94 virulence genes were observed, including pvl, icaA, icaD genes, and microbial surface components that recognize adhesive matrix molecules (MSCRAMMs). We also detected important resistance genes such as blaZ, ant(4), erm(B), fexA, lnu(D), tet(L), and tet(M). The phylogenetic tree listed the species as expected and presented four clades. A variety of virulence and resistance genes were detected. In addition, the expression of important genes such as those responsible for the formation of biofilms and enterotoxins may represent a risk to the health of consumers. being a concern for public health.

PREVALENCE OF BOVINE MASTITIS AND THE FIRST DETECTION OF MYCOPLASMA BOVIS IN VIETNAM’S DAIRY FARMS

Mastitis still remains an economic disease in dairy farms all over the world. This study aimed to report the prevalence of this disease in large-scale farms in Vietnam, the pathogens profile, and first report the detection of Mycoplasma bovis (M. bovis) by applying conventional culture and real-time PCR (polymerase chain reaction) methods. We examined 64,802 enrolled dairy cows from six farms in Vietnam, yielding 1,874 (2.9%) total cases of clinical mastitis. The majority of the 14 pathogens were identified. Klebsiella spp. accounted for 21.0% of the total isolates. Streptococcus uberis (S. uberis), Escherichia coli (E. coli), other Streptococcus spp, and Coagulase-Negative Staphylococci (CNS), followed at 12.6, 7.6, 6.0, and 5.5 percent, respectively. The rest pathogens include Pseudomonas spp., Enterococcus faecalis, Enterobacter spp., Bacillus spp., Citrobacter spp., Pasteurella spp., Proteus spp., and Staphylococcus aureus were isolated with less than 1% each. To the best of our knowledge, this is the first report for detecting M. bovis in mastitis milk samples in Vietnam, where 35 out of 1,422 samples submitted in 2022 were M. bovis positive. Moreover, of the 35 positive cases, 11 cases had only M. bovis, while 24 cases had M. bovis and other pathogens, including 13 Enterobacteriaceae, 7 Streptococcus spp., and 4 CNS.

Laboratory evaluation of a rapid diagnostic test for dairy mastitis.

Rapid diagnostic tests that differentiate between Gram positive, Gram negative and the absence of aerobic bacteria in milk samples from dairy cows with clinical mastitis can support antimicrobial treatment decisions and contribute to a more prudent use of antimicrobials in the dairy industry. The objective of this study was to evaluate the test characteristics of the novel rapid BACT mastitis test in discriminating causes of clinical mastitis under laboratory conditions. Test outcomes of 155 milk samples from clinical mastitis cases were incubated for 14-16 h in the BACT test and compared to results of bacteriological culture. The accuracy for detection of bacterial growth and Gram positive growth was 91 and 89%, respectively. The BACT test could provide an accurate and relatively fast decision tool for farmers to aid in antimicrobial treatment decisions in cases of clinical mastitis.

Economic impact of subclinical mastitis treatment in early lactation using intramammary nisin

Treatment of subclinical mastitis (SCM) during lactation is rarely recommended due to concerns related to both antimicrobial usage and costs associated with milk discard. Nisin is a naturally produced antimicrobial peptide with a Gram-positive spectrum that, when given to dairy cows, does not require milk discard. We evaluated the economic impact of treatment of SCM during early lactation using a nisin-based intramammary treatment under different scenarios which included various treatment costs, milk prices, and cure rates. We stochastically simulated the dynamics of SCM detected during the first week of lactation. The net economic impact was expressed in US dollars per case. The probabilities of an event and their related costs were estimated using a model that was based on pathogen-specific assumptions selected from peer-reviewed articles. Nisin cure rates were based on results of pivotal studies included in the FDA approval submission. Based on our model, the average cost of a case of intramammary infection (i.e., only true positive cases) in early lactation was $170 (90th percentage range = $148 to $187), while the cost of a clinical mastitis case was $521 (90th percentage range = $435 to $581). Both estimates varied with etiology, parity, and stage of lactation. When comparing the net cost of SCM cases (i.e., CMT-positive tests) detected during the first week of lactation, nisin treatment generated an average positive economic impact of $19 per CMT-positive case. Use of nisin to treat SCM was beneficial 93% of the time. Based on the sensitivity analysis, treatment would result in an economically beneficial outcome for 95% and 73% of multiparous and primiparous cows, respectively. At the herd level, use of intramammary nisin to treat SCM in cows in early lactation was economically beneficial in most tested scenarios. However, economic impact was highly influenced by factors such as rate of bacteriological cure, cost of treatment, and parity of affected animal. These factors should be considered when deciding to use nisin as a treatment for SCM.