Clinical Intramammary Infection Research Articles

Strategic administration of antioxidant multiminerals and vitamins to transitional buffaloes augments antioxidant and udder defense mechanisms in early lactation

The aim of the study was to examine the effects of repeated administrations of antioxidant multiminerals and vitamins in transition buffaloes on udder defense mechanism, antioxidant activity and occurrence of intramammary infection (IMI) in early lactation period. Forty clinically healthy pregnant buffaloes were enrolled 45 days before expected date of calving and randomly allocated into five different supplementation groups (n = 8): only basal ration (control), vitamin E and selenium (VES), multiminerals (MM), ascorbic acid (AA) and chromium (Cr) picolinate in basal diet. The udder defense mechanism was monitored by measuring phagocytic activity (PA), myeloperoxidase (MPO) and nitric oxide (NO) productions in milk leukocytes, antioxidant activity was evaluated by measuring total antioxidant capacity (TAC) in plasma and occurrence of IMI was assessed by milk cytology, bacterial count in milk and visible clinical signs of udder until day 28 post-calving. The results showed that the VES and MM supplementations exhibited significantly higher PA, MPO and NO productions of milk leukocytes till first week of lactation whereas, elevated mean TAC in plasma was maintained from day −7 to 1 of calving in MM supplementation group as compared to control group. Statistically, no significant difference in occurrences of subclinical or clinical IMI was noted across the groups until four weeks of lactation. Taken together, it is concluded that repeated administrations of VES and MM to transition buffaloes could be an effective strategy to maintain good udder health by augmenting milk leukocyte functions and antioxidant status and preventing incidence of IMI in early lactation.

Potential factors involved in the early pathogenesis of Streptococcus uberis mastitis: a review.

Bovine mastitis is an inflammation of the mammary gland, which could be the result of allergy, physical trauma, or invasion by pathogens as Streptococcus uberis. This pathogen is an environmental pathogen associated with subclinical and clinical intramammary infection (IMI) in both lactating and non-lactating cows, which can persist in the udder and cause a chronic infection in the mammary gland. In spite of the important economic losses and increased prevalence caused by S. uberis mastitis, virulence factors involved in bacterial colonization of mammary glands and the pathogenic mechanisms are not yet clear. In the last 30years, several studies have defined adherence and internalization of S. uberis as the early stages in IMI. S. uberis adheres to and invades into mammary gland cells, and this ability has been observed in in vitro assays. Until now, these abilities have not been determined in vivo challenges since they have been difficult to study. Bacterial surface proteins are able to bind to extracellular matrix protein components such as fibronectin, collagen and laminin, as well as proteins in milk. These proteins play a role in adhesion to host cells and have been denominated microbial surface components recognizing adhesive matrix molecules (MSCRAMMs). This article aims to summarize our current knowledge on the most relevant properties of the potential factors involved in the early pathogenesis of S. uberis mastitis.

A genomic and proteomic analysis of surface proteins in bovine-adapted lineages of Staphylococcus aureus

In Ireland, Staphylococcus aureus is the most common cause of intramammary infection (IMI) in cattle with the bovine-adapted lineages CC151 and CC97 most commonly found. Surface proteins play a major role in establishing and maintaining the infection. A previous study revealed that a strain from the CC151 lineage showed significant decay in genes encoding predicted surface proteins. Twenty-three S. aureus strains, twelve belonging to CC151 and eleven belonging to CC97, isolated from clinical IMI, were sequenced and genes encoding cell wall anchored (CWA) proteins predicted. Analysis showed that a minority of genes encoding putative CWA proteins were intact in the CC151 strains compared to CC97. Of the 26 known CWA proteins in S. aureus, the CC151 strains only encoded 10 intact genes while CC97 encoded on average 18 genes. Also within the CC97 lineage, the repertoire of genes varied depending on individual strains, with strains encoding between 17-20 intact genes. Although CC151 is reported to internalize within bovine host cells, it does so in a fibronectin-binding protein (FnBPA and FnBPB) independent manner. In-vitro assays were performed and results showed that strains from CC151, and surprisingly also CC97, weakly bound bovine fibronectin and that the FnBPs were poorly expressed in both these lineages. Mass spectrometry analysis of cell wall extracts revealed that SdrE and AdsA were the most highly expressed CWA proteins in both lineages. These results demonstrate significant differences between CC151 and CC97 in their repertoire of genes encoding CWA proteins, which may impact immune recognition of these strains and their interactions with host cells.

Effects of mastitis on ovarian function and fertility in dairy cows

Summary. Mastitis has a deleterious effect on reproductive responses and fertility of dairy cows, which depends on whether it occurs before or after artificial insemination (AI). Subclinical intramammary infection (IMI) before AI reduced steroid concentrations in the preovulatory follicle of approximately one third of lactating cows, and was associated with low expression of major steroidogenic genes. Consequently, IMI induced an attenuated LH surge and delayed ovulation in 30% of cows with subclinical IMI; the remaining 70% exhibited normal responses. The reason for the diversity in reproductive responses of individual cows to subclinical IMI is unclear. Mastitis induced by Gram-negative or Gram-positive bacteria disrupted the developmental competence of the pool of oocytes at the germinal vesicle stage, resulting in low blastocyst rates. The specific immune/inflammatory molecules involved in impairment of reproductive responses in subclinical mastitic cows are poorly documented. Exposure of small antral follicles to subclinical mastitis induced by Gram-positive bacterial toxins had a long-term effect by reducing estradiol concentrations of preovulatory follicles. Unlike chronic subclinical mastitis, the disruptive effect of short-term clinical IMI before AI is time-dependent and involves lowered conception when IMI occurs close to the time of insemination. The effect of clinical intramammary infection on corpus luteum function is equivocal. In a recent study, inter-estrus interval and progesterone concentration were unaltered in most (95%) E. coli-mastitic cows treated with anti-inflammatory drugs. Fertility studies showed that fertility of subclinical mastitic cows is improved by the Ovsynch program, probably because of synchronized timing of ovulation relative to AI in cows that could otherwise exhibit delayed ovulation.

Pathogen group specific risk factors for clinical mastitis, intramammary infection and blind quarters at the herd, cow and quarter level in smallholder dairy farms in Jimma, Ethiopia

A cross-sectional study on clinical mastitis, intramammary infection (IMI) and blind quarters was conducted on 50 smallholder dairy farms in Jimma, Ethiopia. A questionnaire was performed, and quarters of 211 cows were sampled and bacteriologically cultured. Risk factors at the herd, cow, and quarter level for clinical mastitis and (pathogen-specific) intramammary infection were studied using multilevel modeling. As well, factors associated with quarters being blind were studied. Eleven percent of the cows and 4% of the quarters had clinical mastitis whereas 85% of the cows and 51% of the quarters were infected. Eighteen percent of the cows had one or more blind quarter(s), whereas 6% of the quarters was blind. Non-aureus staphylococci were the most frequently isolated pathogens in both clinical mastitis cases and IMI. The odds of clinical mastitis was lower in herds where heifers were purchased in the last year [odds ratio (OR) with 95% confidence interval: 0.11 (0.01–0.90)], old cows (>4 years) [OR: 0.45 (0.18–1.14)], and quarters not showing teat injury [OR: 0.23 (0.07–0.77)]. The odds of IMI caused by any pathogen was higher in herds not practicing teat drying before milking (opposed to drying teats with 1 towel per cow) [OR: 1.68 (1.05–2.69)], cows in later lactation (>180 DIM opposed to ≤90 DIM) [OR: 1.81 (1.14–2.88)], cows with a high (>3) body condition score (BCS) [OR: 1.57 (1.06–2.31)], right quarters (opposed to a left quarter position) [OR: 1.47 (1.10–1.98)], and quarters showing teat injury [OR: 2.30 (0.97–5.43)]. Quarters of cows in herds practicing bucket-fed calf feeding (opposed to suckling) had higher odds of IMI caused by Staphylococcus aureus [OR: 6.05 (1.31–27.90)]. Except for BCS, IMI caused by non-aureus staphylococci was associated with the same risk factors as IMI caused by any pathogen. No access to feed and water immediately after milking [OR: 2.41 (1.26–4.60)], higher parity [OR: 3.60 (1.20–10.82)] and tick infestation [OR: 2.42 (1.02–5.71)] were risk factors for quarters being blind. In conclusion, replacement of old cows, prevention of teat injuries/lesions, drying teats with 1 towel per cow before milking, improving fertility in order to shorten the lactation period, allowing (restricted) suckling, access to feed and water immediately after milking, and improving tick control could improve udder health in Jimma.

UDDER-HALVE-WISE COMPARATIVE PREVALENCE OF CLINICAL AND SUB-CLINICAL MASTITIS IN LACTATING GOATS WITH THEIR BACTERIAL PATHOGENS AND ANTIBIOTIC SENSITIVITY PATTERNS IN BANGLADESH

Goats are the major parts of subsidiary economy of the rural people in Bangladesh. Dairy animals including lactating goats are prone to the intramammary infection (IMI) and associated with a lot of economic impact on the farmers but the reports on caprine mastitis are very limited in inland literature. This study was undertaken to determine the udder-halve-wise comparative prevalence of clinical and sub-clinical caprine mastitis with their associated bacterial pathogens and antibiotic sensitivity patterns during the period from January to May 2010. The teat and udder of a lactating population of 1025 Black Bengal goats maintained under rural (village) condition in two different districts (Joypurhat and Mymensingh) of Bangladesh were physically examined, of which 54 (5.27%) goats had clinical mastitis which constituted as experimental animals for this study. Of the 54 selected goats, 59 (54.63%) udder-halves were affected with clinical mastitis whereas the remaining 49 (45.37%) udder-halves of the selected goats were found physically normal. Out of 59 udder-halves, 49 (90.74%) were unilaterally and 5 (9.26%) were bilaterally affected with clinical mastitis. The prevalence of clinical mastitis was found significantly (p < 0.01) higher in left udder-haves (H = 47; 79.66%) in comparison to the right (H = 12; 20.34%) udder-halves. Milk samples collected from all the 108 udder-halves were examined bacteriologically, of which 102 (94.44%) udder-halves had bacterial infection. No significant differences was observed on the status of bacterial pathogens between clinically (H = 55; 93.22%) and sub-clinically (H = 47; 95.92%) affected udder-halves, and between the single (CH = 45; 76.27% and SCH = 35; 71.43%) and mixed (CH = 10; 16.95% and SCH = 12; 24.49%) bacterial infections in both the clinical and sub-clinical mastitis udder-halves. The major bacterial pathogens isolated were Staphylococcus spp. which showed to be highest frequency (38.98%), followed by Escherichia coli (27.12%) and Bacillus spp. (10.17%) as a single clinical IMI whereas mixed IMI were also detected in both clinically and sub-clinically affected udder-halves. Antibiotic sensitivity results showed a relatively high level of resistance to ampicillin, amoxycillin and streptomycin, whereas gentamicin and ciprofloxacin were found to be the most effective drugs. These results indicate the high prevalence of sub-clinical mastitis in apparently normal quarters of lactating goats than those had clinical mastitis in other udder-halves, and therefore, there is a need for the prudent use of antibacterial in animal health and production through bacteriological and antibiogram studies in Bangladesh.DOI: http://dx.doi.org/10.3329/bjvm.v9i2.13456

Association of conception rate with pattern and level of somatic cell count elevation relative to time of insemination in dairy cows

The aim was to evaluate the effects of mastitis, determined by the pattern and level of somatic cell count (SCC) around first artificial insemination (AI), on conception rate (CR). Data from 287,192 first AI and milk records covering a 7-yr period were obtained from the Israeli Herd Book. Analyses examined the association of probability of conception with SCC elevation relative to timing of AI, using generalized linear mixed models. A SCC threshold of 150,000 cells/mL of milk was set to distinguish between uninfected cows and cows with mastitis. Accordingly, cows with high SCC before and low SCC after AI were designated cured, those with low SCC before and high SCC after AI were designated newly infected, and cows with high SCC before and after AI were designated chronic (likely subclinical) mastitic cows. Compared with uninfected cows, the cured, newly infected, and chronic subgroups showed reduced CR (39.4±0.1, 36.6±0.2, 32.9±0.3, and 31.5±0.2, respectively). In the chronic, subclinical group, probability of conception was lowered by 14.5% in the mild and moderately elevated SCC subgroups and by 20.5% in cows with high SCC elevation compared with the uninfected group (CR of 29.7 vs. 39.4%, respectively). A single high elevation of SCC (>106 cells/mL on only 1 milk test day) lowered the probability of conception by 23.6% when it occurred during the 10 d immediately before AI, but not when it occurred earlier. For 30 d after AI, probability of conception was lowered by about 23%, as reflected in a CR of about 27% compared with the uninfected group. Probability of conception was lowered in cows with uterine and foot health problems (33.9%), in multiparous cows (34.1%), and in cows in the summer (29.1%), but no interactions with mastitis were detected. Results indicate that SCC elevation around AI, typical for subclinical mastitis, was associated with a significant reduction in probability of conception, and that even mild SCC elevation reduced CR. Severe elevation of SCC before AI, typical for clinical intramammary infection, reduced the probability of conception.

Alpha- and β-casein components of host milk induce biofilm formation in the mastitis bacterium Streptococcus uberis

Streptococcus uberis is an environmental udder pathogen that infects cattle and can cause persistent intramammary infection (IMI), despite the fact that isolates are mainly susceptible to antibiotics. As biofilm growth can cause persistent infection, the ability of ten S. uberis isolates from clinical and subclinical IMIs to form biofilms on the polystyrene surface of a conventional 96-microplates model was examined. Biofilm formation was judged by different staining methods (crystal violet and resazurin) and by atomic force and fluorescence microscopy. These analyses revealed that two out of ten S. uberis strains tested were able to form biofilms. Upon treatment with Proteinase K, biofilms of S. uberis were completely disintegrated, which indicates that biofilm formation is protein-mediated in these strains. Addition of trace amounts of milk, the natural growth medium of S. uberis, significantly increased biofilm formation by most of the strains initially classified as non-biofilm producers. Alpha-casein and β-casein were the primary inducers of biofilm growth, and casein degradation by serine protease activity was required to achieve maximal biofilm production. These results suggest that the extracellular proteolytic activity of S. uberis contributes to an increased biofilm formation. Such a mode of growth induced by host proteins might help to explain the persistence of IMIs caused by this pathogen.

A simulation model to calculate costs and benefits of dry period interventions in dairy cattle

An existing dynamic and stochastic bio-economic model of intramammary infection (IMI) caused by Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and Escherichia coli was extended to model the dynamics of IMI during the dry period. These dynamics were modeled on the basis of a Greenwood model. The extended model was used to calculate the cost-effectiveness of different dry period interventions in relation to the annual net costs of IMI in a herd of 100 dairy cows at the start. The interventions were blanket dry cow therapy (BDCT) as the default scenario, BDCT combined with teat sealant (TS), selective dry cow therapy (SDCT) or TS, and SDCT combined with TS. Input parameters of the dynamics of IMI during the dry period and the economic parameters were based on literature. The costs of clinical and subclinical IMI during lactation, clinical IMI during the dry period, and the cost of intervention were used to calculate the combined total annual net cost of IMI per herd. The combined total annual net cost of IMI using the other intervention scenarios was compared to the default scenario (BDCT) to estimate the cost-effectiveness of the other intervention scenarios. Sensitivity analysis was conducted on the parameters involved. The results showed that a considerable number of cows acquire new IMI during the dry period and start the new lactation with IMI. Furthermore, the average combined total annual net cost of IMI per herd using BDCT was € 8800, distributed as € 4561 due to clinical IMI, and € 3063 due to subclinical IMI during lactation, € 88 due to clinical IMI during the dry period, and € 1088 due to antibiotic therapy and labor costs at dry off. On average, application of BDCT combined with TS resulted in € 378 higher combined total annual net cost of IMI compared to the BDCT scenario. Similarly, the SDCT scenarios resulted in higher average combined total annual net costs of IMI compared to the BDCT scenario. The SDCT or TS was on average € 443 higher and the SDCT combined with TS was on average € 635 higher. Sensitivity analysis results showed that the rate of new IMI during the dry period was the most influential parameter on the average combined total annual net cost of IMI. Although the difference between the 4 simulated scenarios was minor, on average BDCT had the lowest combined total annual net cost of IMI.

Stochastic bio-economic model of bovine intramammary infection

Although the dynamics of transmission play an important role in the occurrence of intramammary infection (IMI), they have not been considered in previous models used to estimate the cost of IMI. The bio-economic model described includes within-herd dynamics of pathogen-specific IMI. The model simulated Staphylococcus aureus, Streptococcus uberis, Streptococcus dysgalactiae, and Escherichia coli IMI stochastically and estimated the cost of these IMI in a herd of 100 dairy cows in a situation where a quota is applied to milk production. A Reed–Frost model was used for S. aureus, S. uberis, and S. dysgalactiae IMI and a Greenwood model for E. coli IMI. Economic analysis was conducted per pathogen for clinical and subclinical IMI. The parameters used in the model were based on the literature and were deemed credible and valid. Median annual incidence of clinical and subclinical IMI for all pathogens varied considerably. This variation was greatest for S. aureus IMI . The annual incidence of IMI in a herd of 100 dairy cows caused by S. aureus varied between 0 and 88 cases, with a median of 5 cases and the 5th and 95th percentiles of 0 to 36 for clinical IMI, and a median of 7 cases with the 5th and 95th percentiles of 0 to 52 for subclinical IMI. In consequence, the average total annual net costs also varied widely for S. aureus IMI. Clinical IMI costs were € 1375, with the 5th and 95th percentiles of 0 to 4716 and subclinical IMI costs were € 1219, with the 5th and 95th percentiles of 0 to 4030. The average annual net cost due to the 4 simulated pathogens combined was € 4896 and varied from € 915 to € 11,287 in a herd of 100 dairy cows. The bio-economic model developed for this study will be utilized as a tool to investigate the economic impact of management of pathogen-specific IMI.

Efficacy of a New Premilking Teat Disinfectant Containing a Phenolic Combination for the Prevention of Mastitis

A teat disinfectant containing a phenolic combination was evaluated in a natural exposure study in two dairy research herds. Premilking teat disinfection was compared with a negative control using a split-udder experimental design. In both herds, premilking and postmilking teat disinfections with the phenolic combination were significantly more effective in preventing new intramammary infection (IMI) than was postmilking teat disinfection only. Clinical mastitis and new IMI by Streptococcus uberis, Streptococcus dysgalactiae, Gram-negative pathogens, and coagulase-negative Staphylococcus species were significantly lower in quarters of cows with teats predipped and postdipped than in quarters with teats postdipped only. No chapping or teat skin irritation was observed. Premilking teat disinfection with the phenolic combination in association with good udder preparation and postmilking teat disinfection can further reduce the occurrence of new IMI by numerous mastitis pathogens during lactation.

Epidemiology of Streptococcus uberis intramammary infections in a dairy herd.

From 1987 to 1991, almost 36,000 quarter samples of mammary secretion representing 1790 lactations of 510 dairy cows from a research herd were collected for bacteriological examination. The percentage of cows infected with Streptococcus uberis ranged from 12 to 16% of cows/year. S. uberis was isolated from 14.2% of lactations over the 5-year period. The prevalence of S. uberis intramammary infection (IMI) was significantly higher in cows with > or = 4 lactations than in cows with 3 or fewer lactations. Regardless of lactation number, the prevalence of S. uberis was highest before parturition, during early lactation and near drying off. The prevalence of S. uberis infected quarters ranged from 1.3 to 2.3% of quarters/year; the prevalence rate for the 5-year period was 2% of quarters. The quarter prevalence of S. uberis was lowest in cows with < or = 3 lactations, increased significantly with lactation number and was highest in cows with > or = 6 lactations. The percentage of quarters infected with S. uberis varied significantly by year. The majority (95%) of S. uberis IMI were subclinical. The ratio of subclinical IMI to clinical IMI was lowest during early lactation, and increased with days in milk, and with lactation age except for cows in their 5th and 6th lactations. Results of this epidemiological investigation suggest that opportunities exist where suitable control measures could be applied to reduce the impact of S. uberis infections in the dairy herd.