Intramammary Antibiotic Treatment Research Articles

Draft genome sequence of a multidrug-resistant Pseudomonas aeruginosa strain isolated from a dairy cow with chronic mastitis.

Pseudomonas aeruginosa is considered an environmental pathogen, and it can cause acute and chronic mastitis in dairy cows. Here, we report the draft genome sequence of a multidrug-resistant P. aeruginosa strain (2011C-S1) isolated from a Holstein cow showing signs of chronic mastitis that was nonresponsive to intramammary antibiotic treatment.

In Vitro Evaluation of the Antimicrobial Properties of Nanoparticles as New Agents Used in Teat Sealants for Mastitis Prevention in Dry Cows.

Mastitis prevention and treatment in dry cows are complex issues with limited solutions. The most common is intramammary antibiotic treatment. However, the effectiveness of this treatment varies among countries and even within herds in the same region. Therefore, it is necessary to develop new strategies for dry cow therapy. Metal nanoparticles (NPs), which have strong biocidal properties for treating diseases caused by bacteria, fungi, and algae, are increasingly used to reduce antibiotic use. In this study, AuNPs, CuNPs, AgNPs, PtNPs, NP-FeCs, and their triple complexes were used at different concentrations to evaluate their practical use in treating cows during their dry period. The nanoparticles were in hydrocolloid form and were added separately to form a mixture with beeswax, a mixture with oil, or a mixture based on vegetable glycerin and propylene glycol. The NPs' concentrations were 0.5, 1, 2, and 5 ppm. Gram-positive and Gram-negative bacteria, and fungi isolated from cows diagnosed with mastitis were used to determine pathogen viability. The results indicated that AuNPs, CuNPs, AgNPs, and their complexes show biocidal properties against mastitis pathogens. AgNPs at 5 ppm had the strongest biocidal properties and reduced Streptococcus agalactiae's survival rate by 50%; however, the nanoparticle complexes showed poor synergism. The strongest biocidal properties of NPs in wax and in glycerin mixed with glycol were shown against Escherichia coli. Additionally, low nanoparticle concentrations showed no cytotoxicity for BME-UV1 bovine cells, suggesting that these mixtures might be used for further in vivo testing.

Effect of the Selective Dry Cow Therapy on Udder Health and Milk Microbiota.

Recently, the use of antimicrobials on dairy farms has been significantly limited from both the legislative and consumer points of view. This study aims to check the efficacy of selective dry cow therapy (SDCT) versus blanket dry cow therapy (BDCT) on bovine udder in healthy animals. SDTC is when an antibiotic is administered only to infected cows, compared with BDCT, where all cows receive an antimicrobial, regardless of their infection status. The milk samples were collected from enrolled Holstein Friesian cows 7 days before dry-off (T0) and 10 days after calving (T1) to assess somatic cell count (SCC), intramammary infections (IMIs), and milk microbiota variation. After pre-drying sampling, cows are randomly assigned to the following treatments: internal teat sealant alone (ITS; 24 cows), which is a treatment in a cow that does not receive antibiotics in SDTC, or in combination with intramammary antibiotic treatment (A+ITS; 22 cows). Non-statistically significant results are found between the two treatment groups at T1 for SCC, milk yield, and alpha diversity in milk microbiota. A statistically (p < 0.033) T1 IMI decrease is reported in the A+ITS group, and a significant beta diversity analysis is shown between the two timepoints (p = 0.009). This study confirms the possibility of selective drying without new IMI risk or increased SCC at calving, considering healthy cows without contagious infections and SCC values >200,000 cells/mL in the previous lactation.

Prevalence, Virulence, and Antibiotics Gene Profiles in Lactococcus garvieae Isolated from Cows with Clinical Mastitis in China.

Lactococcus garvieae (L. garvieae) is a pathogenic gram-positive, catalase-negative (GPCN) bacterium that causes bovine mastitis. A total of 49 L. garvieae isolates were identified from 1441 clinical mastitis (CM) samples. The pathogenic effects of L. garvieae were studied with two infection models: bovine mammary epithelial cells cultured in vitro and murine mammary infections in vivo. The overall farm prevalence was 15.5% (13/84 farms in 9/19 provinces) and sample prevalence was 3.40% (49/1441). Post-treatment somatic cell count (SCC) post L. garvieae infection was significantly higher than the other GPCN pathogens isolated, and the bacteriological cure fraction was 41.94% (13/31) after intramammary antibiotic treatment. All L. garvieae isolates were resistant to rifaximin, 12.24% of isolates were resistant to cephalexin, and 10.20% (5/49) were multidrug-resistant (MDR). The most prevalent virulence genes were Hemolysin 1 (hly1)(100%), Hemolysin 2 (hly2) (97.96%), NADH oxidase (NADHO) (100%), Superoxide dismutase (SOD) (100%), Adhesin Pav (Pav) (100%), Adhesin PsaA (PsaA) (100%), Enolase (eno) (100%), Adhesin cluster 1(AC1) (100%), Adhesin cluster 2 (AC2) (100%), and several exopolysaccharides. L. garvieae rapidly adhered to bovine mammary epithelial cells, resulting in an elevated lactate dehydrogenase release. Edema and congestion were observed in challenged murine mammary glands and bacteria were consistently isolated at 12, 24, 48, 72, and 120 h after infection. We concluded that L. garvieae had good adaptive ability in the bovine and murine mammary cells and tissue. Given the resistance profile, penicillin and ampicillin are potential treatments for CM cases caused by L. garvieae.

A stochastic modelling approach to determine the effect of diverse Staphylococcus aureus strains on the economic and epidemiological outcomes of mastitis intervention strategies in dairy cattle

Staphylococcus aureus (S. aureus) strains with considerable genetic and phenotypic differences have previously been identified. The economic and epidemiologic impact of S. aureus mastitis has been investigated, but none of these studies took differences between strains into account. Here we aimed to investigate how differences between S. aureus strains affect the economic and epidemiologic outcome of various intervention strategies against clinical and subclinical intramammary infections. Five S. aureus strains were modelled using a stochastic bio-economic model simulating a dairy herd of 200 cows using single-day time steps. The strain characteristics of the five simulated S. aureus strains (general, contagious, spill-over, clinical and persistent) were based on divergent phenotypes as described in literature. Outcomes of the model included incidence (both clinical and subclinical), number of antibiotic treatment days, number of culled cows, and net income. Intervention strategies against clinical and subclinical intramammary infections were based on (variations of) intramammary antibiotic treatment, testing, and culling. Both single and multiple pathogen (intramammary infection caused by S. aureus, Escherichia coli, and non-aureus staphylococci) scenarios were simulated to determine the effect of the five S. aureus strains on the impact of 19 different intervention strategies. The results showed that the incidence (both clinical and subclinical), number of treatment days, number of culled cows, and net income varied considerably for the different S. aureus strains. Comparison of the model outcomes within and between strains showed that for most intervention strategies the relative impact differed per strain. However, the intervention strategy with the best outcome for most variables and strains was the culling of cows with a recovery probability lower than 50%. This shows that the relative economic and epidemiologic impact of most of the modelled intervention strategies were strain-dependent, while some intervention strategies were not strain-dependent. From this, we conclude that, depending on the intervention strategy applied on a farm, it could be advantageous to type S. aureus to determine whether it would be economically and epidemiologically beneficial for the existing intervention strategy to be changed.

Treating clinical mastitis in dairy herds: a role for on farm culture?

The focus on the rational use of antibiotics in dairy herds has meant that mastitis control has received renewed interest, particularly around prevention of new infections and alternative treatment strategies. The former has seen the development of a new industry initiative (QuarterPRO) to help advisors and farmers reduce the rate of new infections and index cases. The latter has seen widespread uptake of the selective use of intramammary antibiotic for infected cows at drying-off, a reminder to the veterinary profession as well as clients about the general lack of evidence for the use of parenteral antibiotic in combination with intramammary antibiotic for mild and moderate clinical mastitis events, and finally the potential to select intramammary antibiotic treatment for clinical mastitis using on farm culture (OFC). It is important that veterinary surgeons are aware of the research around the development and use of OFC and the suitability of individual herds for this approach. Whereas antibiotics may not be required for mild clinical mastitis events caused by some pathogens, particularly Escherichia coli, it is important that clinical mastitis events (particularly first cases in a lactation cycle) caused by Gram-positive pathogens such as Streptococcus spp. and Staphylococcus aureus are treated with intramammary antibiotic to optimise chance of cure and reduce risk of transmission. With this in mind, we need to consider individual herd cell count data, herd pathogen profile and ensure careful monitoring of outcomes for clinical mastitis cases in herds that are selecting treatment based on OFC, particularly for index (first) cases in a cow's lactation.

Randomized controlled field trial comparing quarter and cow level selective dry cow treatment using the California Mastitis Test

Selective use of antibiotic dry cow treatment can be implemented at the cow or quarter level, with the latter having the potential to further reduce antibiotic use. Our objective was to compare these 2 approaches in 6 herds in the United Kingdom in which environmental mastitis predominated. Eight hundred seven cows were enrolled and categorized as having a high cell count (n = 401) or low cell count (n = 406) in the last 3 mo of lactation and clinical mastitis history. All quarters of all enrolled cows received an internal teat sealant. Within each category, cows were randomly allocated to 1 of 3 groups; in one group antibiotic treatment was allocated at cow level (i.e., all 4 quarters received antibiotic), whereas in the 2 remaining groups antibiotic treatment was allocated at quarter level, based on California Mastitis Test (CMT) findings. Two different thresholds, score 1 and 2, were used to determine likely infection status. Quarter milk samples were collected at dry off and postcalving for bacteriological culture and somatic cell count (SCC). Cows were monitored for clinical mastitis from dry off until 100 d in milk. Cow level SCC and milk yield data were collated from farm records. Within each category, the 2 quarter level treatment groups were compared with cow level treatment at dry off. Leaving quarters untreated with intramammary antibiotic in cows in the high cell count group, with a CMT <2 or <1, reduced antibiotic use by 55% and 31%, respectively, and resulted in no difference in the odds of being infected with any pathogen postcalving, but was associated with a higher SCC at the first test day. Intramammary antibiotic treatment of quarters with a CMT ≥1 in cows in the low cell count category at dry off was not associated with any reduction in the odds of being infected with a major pathogen postcalving but was associated with a decrease in the odds of being infected with a minor mastitis pathogen postcalving. The use of antibiotics in quarters of cows categorized as low cell count at dry off, increased the proportion of quarters treated with antibiotic from 0% at cow level to 31% (CMT ≥ 1) and 12% (CMT ≥ 2) at quarter level, only resulting in a reduction in SCC of around 20,000 cells/mL at the first test day, if all quarters with CMT score ≥1 were treated with antibiotic. No differences in clinical mastitis incidence and milk yield in the first 100 d in milk were detected between any of the treatment groups. These study findings support selective quarter level dry off treatment only in cows with cow level SCC >200,000 cells/mL at dry off.

Reducing antibiotic use in the control of mastitis in dairy herds

Abstract The control of mastitis remains a focus of attention for dairy farmers, veterinary surgeons and advisors due to its impact on cow health and welfare, milk quality, sustainable production, and the financial costs associated with treatment, prevention and ongoing control. In addition, the focus on the unnecessary use of antibiotics in agriculture has meant that mastitis control in dairy herds has received renewed interest, particularly around prevention of new infection and alternative treatment strategies. The latter includes the selective use of intra-mammary antibiotic for infected cows at drying-off, reserving parenteral antibiotic for clinical cases where the cow is ill, and selecting intra-mammary antibiotic treatment for clinical mastitis based on culture results. Treating clinical mastitis caused by Gram-positive pathogens such as Streptococcus spp. with intra-mammary antibiotic remains important to optimise chance of cure and reduce risk of transmission of infection, although antibiotics may not be required for clinical mastitis infections caused by other pathogens, particularly E. coli . The long-term reduction and rationalisation of antibiotic use in mastitis control is achieved through improved management to prevent new infections and avoid the need to treat mastitis. This comes through understanding the predominant epidemiological ‘pattern’ of infection in the herd and targeted implementation of well-specified interventions to reduce the rate of new infection, either in lactation or during the dry period. For most dairy herds, environmental mastitis pathogens predominate and therefore management and hygiene of housed and pastured environments is a key component of mastitis control plans designed to reduce the need to use antibiotics in mastitis control.

Milk microbiome: evaluation study on the differences among cows with a different health status classified by leukocyte pattern

Milk microbiome: evaluation study on the differences among cows with a different health status classified by leukocyte pattern

Efficacy of cabergoline in a double-blind randomized clinical trial on milk leakage reduction at drying-off and new intramammary infections across the dry period and postcalving

The abrupt cessation of milking at dry-off may induce milk leakage, which may increase the risk of new intramammary infections (IMI). This study assessed the efficacy of 1 i.m. injection of 5.6 mg of cabergoline (Velactis, Ceva Santé Animale, Libourne, France) at drying-off on milk leakage after dry-off and new IMI across the dry period and postcalving compared with a placebo (negative control) and an intramammary antibiotic treatment (positive control) under field conditions. The study was a double-blind, randomized, 3-arm, multicenter, clinical trial performed under Good Clinical Practice conditions. Data from 900 dairy cows of various breeds from 63 farms in France, Germany, and Hungary were analyzed. Only quarters with no bacterial growth at drying-off and a cow somatic cell count ≤200,000 cells/mL were included. Quarters infected with major or minor pathogens or cows with high somatic cell count at time of inclusion were excluded. Cows that qualified for the study were visited 7 times in total before and after drying-off and after calving. Presence (yes/no) of milk leakage was recorded on the day after dry-off. A new infected quarter (new IMI) was defined as one with a major pathogen present in any one of the 2 postcalving samples. Two mixed logistic regression models were fitted to the data to evaluate the efficacy of cabergoline in the reduction of milk leakage and new IMI. One i.m. injection of cabergoline at drying-off significantly reduced the incidence of milk leakage the day after dry-off compared with both placebo and antibiotic treatment. Cabergoline-treated cows significantly reduced the risk of new IMI by major pathogens across the dry period and postcalving by 21% when compared with placebo cows (20.5 vs. 26.0%, respectively). However, when milk leakage was added to the model, the significance of cabergoline was reduced. We interpreted this to show that milk leakage is an intervening variable between treatment with cabergoline and lower risk of new IMI. The antibiotic treatment significantly decreased the odds of new IMI compared with both cabergoline and placebo. However, because several countries are currently disallowing the preventive use of antibiotics at dry-off in noninfected quarters, the dry-off facilitator cabergoline may therefore be of particular value to reduce the risk of new IMI across the dry period.

Negatively controlled, randomized clinical trial to evaluate intramammary treatment of nonsevere, gram-negative clinical mastitis

The objective of this negatively controlled, randomized clinical trial was to examine clinical outcomes of 2-d or 8-d treatment using an approved intramammary (IMM) product containing ceftiofur hydrochloride compared with no antimicrobial treatment of nonsevere, gram-negative cases of clinical mastitis (CM). Additionally, we contrasted clinical outcomes of cases caused by Escherichia coli (n = 56) or Klebsiella pneumoniae (n = 54). Cases (n = 168) of nonsevere (abnormal milk or abnormal milk and udder) CM were randomly assigned to receive 2 d (n = 56) or 8 d (n = 56) of IMM ceftiofur or assigned to a negative control group (n = 56). At enrollment, quarter milk samples were collected and used for on-farm culture, somatic cell count (SCC), and confirmatory microbiological analysis. Quarter milk samples were collected weekly from 7 to 28 d after enrollment for microbiological and SCC analysis. Clinical outcomes were followed for 90 d or until the end of lactation (follow-up period, FUP). Overall, no significant differences in quarter-level recurrence of CM (32% for negative control, 34% for the 2-d treatment, and 32% for the 8-d treatment), culling (18% for negative control, 12% for 2-d treatment, and 11% for 8-d treatment), voluntary dry-off of affected quarters (20% for negative control, 30% for 2-d treatment, and 27% for 8-d treatment), days until return to normal milk (4.2 days for negative control, 4.8 days for 2-d treatment, 4.5 days for 8-d treatment), weekly quarter-SCC during the FUP (6.1, 6.3, and 6.0 log10SCC for the negative control, 2-d, and 8-d treatments, respectively), or daily milk yield during the FUP (37.1, 36.3, and 37.6 kg/cow per day for the negative control, 2-d, and 8-d treatments, respectively) were observed among experimental groups. Days of discarded milk were greater for cows assigned to 8-d IMM ceftiofur (11.1 d) than for cows assigned to 2-d (6.9 d) or cows assigned to negative control (5.6 d). Bacteriological cure (BC) at 14 and 21 d after enrollment was greater in cows assigned to 8-d (89%) and 2-d (84%) treatment than in cows assigned to negative control (67%), but this outcome was confounded by pathogen. For CM caused by Kleb. pneumoniae, BC was greater for quarters assigned to receive treatment (combined 2-d and 8-d groups; 74% BC) than for quarters assigned to negative control (18%). In contrast, no differences in BC were observed for CM caused by E. coli (97-98%). Culling and voluntary dry-off of affected quarters were significantly greater for cows with quarters affected by Kleb. pneumoniae (22% culled, 39% voluntary dry-off of quarters) than for cows with quarters affected with E. coli (7% culled, 11% voluntary dry-off of quarters). Overall, use of IMM ceftiofur did not result in improvement of most clinical outcomes, but differences between E. coli and Kleb. pneumoniae were evident. In contrast to E. coli, Kleb. pneumoniae caused chronic intramammary infection and induced worse clinical outcomes. Intramammary antibiotic treatment of most mild and moderate cases of CM caused by E. coli is not necessary, but more research is needed to identify which quarters affected by Kleb. pneumoniae may benefit from antimicrobial therapy.

Prevalence Reduction of Contagious Mastitis Pathogens in a Holstein Dairy Herd Under Tropical Conditions

The aim of this study was to evaluate the reduction of intramammary infection caused by Streptococcus agalactiae and Staphylococcus aureus in a Holstein dairy herd under tropical conditions. The period of study was from January 2012 from January 2013 in a dairy herd composed by Holstein cows, with an average of 142 lactating cows/month. Milk samples were collected from individual lactating cows for microbiological tests. The sampling lactating cows was in order to identify those infected by Streptococcus agalactiae for the treatment of all mammary quarters with intramammary antibiotics, as well as to identify chronically infected lactating cows by S. aureus for possible culling. During this period, 161 treatments of cows with an intramammary antibiotic were performed to eliminate Streptococcus agalactiae, and nine cows chronically infected with Staphylococcus aureus were culled. The percentages of infected cows with S. agalactiae in January 2012 and January 2013 were 61.6% and 2.2%, respectively. For the same months, the percentages of cows infected with S. aureus were 28.3% and 19.4%, respectively. The intramammary antibiotic treatment of lactating cows was efficient in eliminating infection caused by S. agalactiae and consequently the prevalence of infected animals in the herd. The reduction in S. aureus prevalence among cows was associated with the culling of cows chronically infected by this pathogen.

Normal milk microbiome is reestablished following experimental infection with Escherichia coli independent of intramammary antibiotic treatment with a third-generation cephalosporin in bovines

BackgroundThe use of antimicrobials in food animals and the emergence of antimicrobial resistance are global concerns. Ceftiofur is the only third-generation cephalosporin labeled for veterinary use in the USA, and it is the drug of choice in the majority of dairy farms for the treatment of mastitis. Here, we use next-generation sequencing to describe longitudinal changes that occur in the milk microbiome before, during, and after infection and treatment with ceftiofur. Twelve animals were intramammary challenged with Escherichia coli in one quarter and randomly allocated to receive intramammary treatment with ceftiofur (5d) or untreated controls. Serial samples were collected from −72 to 216 h relative to challenge from the challenged quarter, an ipsilateral quarter assigned to the same treatment group, and from a third quarter that did not undergo intervention.ResultsInfection with E. coli dramatically impacted microbial diversity. Ceftiofur significantly decreased LogCFUs but had no significant effect on the milk microbiome, rate of pathogen clearance, or somatic cell count. At the end of the study, the microbial profile of infected quarters was indistinguishable from pre-challenge samples in both treated and untreated animals. Intramammary infusion with ceftiofur did not alter the healthy milk (i.e., milk devoid of clots or serous appearance and collected from a mammary gland that shows no clinical signs of mastitis) microbiome.ConclusionsOur results indicate that the mammary gland harbors a resilient microbiome, capable of reestablishing itself after experimental infection with E. coli independent of antimicrobial treatment.

Changes in behaviour of dairy cows with clinical mastitis

Behaviour is an important tool for recognizing illness in animals. One of the most common diseases in dairy cattle is clinical mastitis. Evidence suggests that cows with this disease show sickness behaviours, but little is known about the progression of behavioural changes before and after the disease becomes clinical. The aims of this study were to determine changes in feeding and competitive behaviour at the feed bunk of dairy cows before the diagnosis of clinical mastitis and determine the effect of intramammary antibiotic treatment on behaviour. Dry matter intake, feeding time, number of visits to the feeder, rate of feed intake, number of replacements occurring at the feeder (when one cow displaced a feeding cow and took her position at the feed bin) and the percent of intake during peak feeding time were measured daily in eight cows diagnosed with clinical mastitis in one quarter of the udder. Clinical mastitis was diagnosed based on daily rectal body temperature as well as condition of the foremilk and udder assessed by the milker at each milking from calving until 30 days in milk. Starting on the day of diagnosis, cows received an intramammary antibiotic twice daily for three consecutive days. During the 5 days period before diagnosis, cows decreased feed intake by 1.2kg/d (SE=0.2, P<0.001) but showed no other changes in feeding behaviour during this time. The frequency of competitive replacements at the feeder (slope=−2.3 no./d, SE=1.0, P=0.04) and the percentage of intake at peak feeding time (slope=−1.8%, SE=0.6, P=0.008) were lower compared to day of diagnosis. Following treatment, cows immediately increased feed intake, feeding time and competitive replacements at the feeder. These results show that cows with naturally occurring clinical mastitis exhibit signs of sickness behaviour in the days before diagnosis, and that these behaviours rapidly recover in the days after treatment.

Withdrawal periods and tissue tolerance after intramammary antibiotic treatment of dairy goats with clinical mastitis

The aim of this study was to determine withdrawal periods (WP) and tissue irritation after administration of three intramammary antibiotics [Curaclox LC (Norbrook (ARK AH)], Spectrazol Milking Cow (Schering-Plough AH) and Rilexine 200 LC [Logos Agvet (Virbac)] in goats with clinical mastitis. Withdrawal periods in goats with clinical mastitis treated with Curaclox LC, were not significantly different from those recommended for use in cows (72 h) with (67 h) or without (48 h) the 24 h mandatory safety margin while Spectrazol caused a significantly longer withdrawal period (122 h) than that recommended for use in cattle with (60 h) and without (36 h) the 24h safety margin. The withdrawal period of clinical mastitis cases treated with Rilexine 200 LC was 48 h compared to the 96 h recommended for use in cows. A linear model of regression with factors influencing the WP in goats with clinical mastitis was as follows: WP = 30.21 + 4.692 (sampling time) + 22.11 (udder pathology) - 13.6 (floccules) - 0.00649 (milk yield). Somatic Cell Counts (SCC) of milk from udder halves with clinical mastitis ranged from 7,053 x 10(3) to 7,948 x 10(3) cells per ml without isolations of bacteria and between 6,476 x 10(3) and 8,479 x 10(3) cells per ml with isolations of bacteria. Most of the variation in SCC could not be explained and the California Milk Cell Test (CMCT) and SCC on their own were not reliable methods for mastitis diagnosis. However, CMCT and SCC were indicators of udder irritation. In goats without clinical mastitis, Spectrazol Milking Cow caused the least tissue irritation followed by Rilexine 200 LC and Curaclox LC. For goats with clinical mastitis, Rilexine 200 LC caused the least irritation, followed by Curaclox LC while Spectrazol Milking Cow caused the most irritation.

Intramammary infections in heifers during early lactation following intramammary infusion of pirlimycin hydrochloride or penicillin-novobiocin at the first milking after parturition

A study was conducted to determine whether intramammary antibiotic treatment of heifer mammary glands following the first milking after calving was effective for reducing the percentage of mammary quarters infected during early lactation. Jersey and Holstein heifers from two research herds were assigned to one of three treatment groups: (1) no intramammary infusion following the first milking after parturition, (2) intramammary infusion of all quarters with pirlimycin hydrochloride following the first milking after parturition and (3) intramammary infusion of all quarters with novobiocin sodium plus penicillin G procaine following the first milking after parturition. Almost 93% of Jersey heifers (40/43) and 73.1% of quarters (125/171) were infected at the first milking. Almost 77% of quarters (33/43) were cured following treatment with pirlimycin, 61.8% (21/34) were cured following treatment with penicillin-novobiocin and 39.6% (19/48) of infections were eliminated spontaneously in the untreated control group. Significantly fewer infections were observed in pirlimycin or penicillin-novobiocin treated mammary glands of Jersey heifers during early lactation than in untreated control mammary glands. Almost 89% of Holstein heifers (32/36) and 52.8% of quarters (76/144) were infected at the first milking. About 57% (12/21) of quarters were cured following treatment with pirlimycin, 41.4% (12/29) were cured following treatment with penicillin-novobiocin and 23.1% (6/26) of infections were eliminated spontaneously in the untreated negative control group. Significantly fewer infections were observed in pirlimycin treated mammary glands of Holstein heifers during early lactation than in untreated control mammary glands. However, no significant differences were observed following penicillin-novobiocin treatment of Holstein heifers after the first milking of lactation compared with untreated control quarters. Coagulase-negative staphylococci, Streptococcus uberis and Streptococcus dysgalactiae subsp dysgalactiae were isolated most frequently in heifers from both herds.

Efficacy of Intramammary Pirlimycin as a Pre-calving Antibiotic Treatment for Nulliparous Heifers

Recently, more and more studies indicate that intramammary infection (IMI) in peripartum heifers are frequent and associated with financial losses. The objective of this study was to evaluate the effectiveness of an intramammary antibiotic treatment (pirlimycin) during the pre-calving period on the proportion of intramammary infection (IMI) in heifers at the onset of lactation as well as on milk production and somatic cell count (SCC) during their first lactation.

Outbreak of Candida rugosa mastitis in a dairy herd after intramammary antibiotic treatment

Veterinary RecordVolume 156, Issue 25 p. 812-813 Short Communication Outbreak of Candida rugosa mastitis in a dairy herd after intramammary antibiotic treatment W. M. Crawshaw BVetMed, DCHP, MRCVS, W. M. Crawshaw BVetMed, DCHP, MRCVS SAC Veterinary Services Group, Auchincruive, Ayr, KA6 5AESearch for more papers by this authorN. R. MacDonald BVMS, MRCVS, N. R. MacDonald BVMS, MRCVS 16 Kilmarnock Road, Mauchline, Ayrshire, KA5 5DESearch for more papers by this authorG. Duncan HNC, G. Duncan HNC SAC Veterinary Services Group, Auchincruive, Ayr, KA6 5AESearch for more papers by this author W. M. Crawshaw BVetMed, DCHP, MRCVS, W. M. Crawshaw BVetMed, DCHP, MRCVS SAC Veterinary Services Group, Auchincruive, Ayr, KA6 5AESearch for more papers by this authorN. R. MacDonald BVMS, MRCVS, N. R. MacDonald BVMS, MRCVS 16 Kilmarnock Road, Mauchline, Ayrshire, KA5 5DESearch for more papers by this authorG. Duncan HNC, G. Duncan HNC SAC Veterinary Services Group, Auchincruive, Ayr, KA6 5AESearch for more papers by this author First published: 18 June 2005 https://doi.org/10.1136/vr.156.25.812Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article.Citing Literature Volume156, Issue25June 2005Pages 812-813 RelatedInformation

Factors Affecting Cure and Somatic Cell Count After Pirlimycin Treatment of Subclinical Mastitis in Lactating Cows

This study investigated the associations of both bacteriological cure and quarter somatic cell count (SCC) after intramammary antibiotic treatment with treatment duration, cow characteristics, and pretreatment bacteriology and SCC. For the purpose of this paper, data from 2 treatment groups in each of 2 multi-location studies were selected. These studies were conducted to evaluate the efficacy of daily intramammary infusions with 50mg of pirlimycin hydrochloride for the treatment of subclinical mastitis. Data from study 1 allowed for comparison of a group of cows that received pirlimycin intramammarily for 2 d with a group that received no treatment, and study 2 provided data for comparison of pirlimycin for 2 d with pirlimycin for 8 d. Quarter milk samples from cows with a high monthly SCC were tested for bacteriology and SCC. If one or more quarters had both a positive bacteriology and an SCC ≥300,000 cells/mL, the cow was enrolled and randomly allocated to a treatment group. Enrolled cows were monitored for clinical mastitis and other disease for 4 wk after treatment initiation. At 3 and 4 wk after treatment initiation, milk samples were taken from each enrolled quarter to determine the SCC and conduct a bacteriological culture. Bacteriological culture results were interpreted such that quarters where the same bacterial species was cultured before treatment and found in at least 1 of the 2 posttreatment samples were considered a failure. The analysis of SCC used a mixed linear model (SAS proc mixed) and the analysis of bacteriological cure used a mixed logistic model (SAS glimmix macro). Bacteriological cure rate was significantly higher for lower parity, lower number of colonies in the pretreatment culture, longer treatment duration, and for streptococci compared with Staphylococcus aureus. However, treatment regimen affected bacteriological cure differently in major than in minor pathogens and there was a significant interaction of treatment regimen with stage of lactation. Posttreatment SCC was significantly higher with increasing parity, in rear quarters, and with shorter duration of treatment. In the group of second and third parity animals, post-treatment SCC was more reduced in front quarters than in rear quarters. Also, the difference in posttreatment SCC between younger and older cows increased with higher pretreatment SCC. In conclusion, when predicting bacteriological cure following treatment of subclinical mastitis during lactation both treatment regimen and other risk factors need to be considered. The other risk factors may vary with treatment regimen. Posttreatment SCC was associated with treatment regimen, other risk factors, and interactions among the other risk factors; but these other risk factors did not vary significantly with treatment regimen.

The ability of the enzyme-linked immunosorbent assay to detect antibody against Staphylococcus aureus in milk following experimental intramammary infection.

Changes in the milk antibody levels against Staphylococcus aureus were measured at the start of an experimental intramammary instillation of either S. aureus (Study I) or Staphylococcus hyicus (Study II). A commercial enzyme-linked immunosorbent assay system was used. Twenty-one Holstein cows were enrolled in Study I and 15 Holstein cows were used in Study II. Pathogen instillation began 21 days before the start of the non-lactating period. Cows received intramammary antibiotic treatment in all quarters immediately after the last milking, the start of the non-lactating period. Lacteal secretions were collected before the start of the non-lactating period, and during the immediate postpartum period in both studies, and during the non-lactating period in Study I. Milk was cultured for mastitis pathogens and S. aureus antibody levels and somatic cell counts were determined from all samples. There was an approximate 2-week delay in the elevation in antibody levels in response to the instillation of S. aureus. Antibody levels remained elevated in cows with S. aureus intramammary infections postpartum, but were below threshold in cows where intramammary infections were cured during the non-lactating period. Antibody levels were elevated by S. hyicus intramammary infections, remained elevated for the first 12 days postpartum, but were below threshold by day 21 postpartum. Cows with incipient intramammary S. aureus infections might be misclassified as false negatives by the antibody test. However, results suggest that cows with S. hyicus intramammary infections that were not cured would not be misclassified if milk is withheld from test for the first 30 days postpartum, as recommended by the manufacturer of the test.