Efficacy of a 0.1% iodine teat dip against Staphylococcus aureus and Streptococcus agalactiae during experimental challenge.

An experimental challenge trial was performed according to the guidelines recommended by the National Mastitis Council (NMC). A 0.1% iodine teat dip (Quartermate with I-Tech) was examined. This product gave an 87.9% reduction of new intramammary infections with Staphylococcus aureus and a 66.5% reduction for Streptococcus agalactiae compared with a negative control. Teat end and teat skin characteristics remained excellent throughout the trial.

Efficacy of two iodine teat dips during experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

An experimental challenge trial was performed against Staphylococcus aureus and Streptococcus agalactiae following the procedures recommended by the National Mastitis Council. The efficacy of two teat dips, product 1 (Bovadine with I-Tech II) and product 2 (Bovadine with I-Tech, used as a positive control), was determined. Both teat dips contain 1% iodine and 10% glycerin. Product 1 established an 89.7% reduction in infections against Staph. aureus and 73.1% reduction in infections against Strep. agalactiae. Product 2 demonstrated an 86.2% reduction in infections against Staph. aureus and 78.4% reduction in infections against Strep. agalactiae. Teat skin and teat ends were evaluated before and after the trial. No significant change in teat condition was observed for either product.

Germicidal activities of representatives of five different teat dip classes against three bovine mycoplasma species using a modified excised teat model.

Six representative teat dips from five different teat dip classes were tested for germicidal activity against challenge exposure to Mycoplasma bovis, Mycoplasma californicum, and Mycoplasma bovigenitalium using a modified excised teat model. All teat dip formulations tested were efficacious against all of the Mycoplasma species, providing bacterial logarithmic reductions above 4. The germicides performed best against M. bovigenitalium with an average log reduction (LR) of 6.29. Average LR were 5.41 and 5.70 against M. bovis and M. californicum, respectively. The iodine and chlorhexidine products performed best against M. bovis and M. californicum, respectively, with complete kill of all organisms. The chlorhexidine and the barrier chlorine product also had complete kill of M. bovigenitalium organisms.

Reduction of mastitis caused by experimental challenge with Staphylococcus aureus and Streptococcus agalactiae by use of a quaternary ammonium and halogen-mixture teat dip.

A teat-dip formulation containing sodium dichloro isocyanuric acid, bronopol, and quaternary ammonium was tested for efficacy against Staphylococcus aureus and Streptococcus agalactiae intramammary infections (IMI) using an experimental challenge model. Sixty-two Jersey cows from the Hill Farm Research Station (Homer, LA) were used in an 8-wk controlled infection trial to evaluate the teat dip. During the afternoon milking, Monday through Friday for 8 wk, all teats of each cow were immersed to a depth of approximately 25 mm in a challenge suspension containing approximately 5 x 10(7) cfu of Staphylococcus aureus and approximately 5 x 10(7) cfu of Streptococcus agalactiae immediately after milking machines were removed. Immediately after challenge, the distal 25 mm of two contralateral teats were dipped with the experimental teat dip; the remaining two teats served as undipped controls. The experimental teat dip reduced the number of new Staph. aureus IMI by 70.9% and reduced the number of new Strep. agalactiae IMI by 60.0%. Teat end and teat skin condition were characterized as normal and without irritation at the completion of the study. The combination of the three germicides in this experimental teat dip is unique and an effective formulation without adverse effects on condition of teat ends or teat skin.

Prevalence of mastitis in dairy heifers and effectiveness of antibiotic therapy.

Dairy heifers were treated 0 to 90 d, 90 to 180 d, or 180 to 270 d prepartum with one of five different antibiotic products to determine the best time and with which product they should be treated prior to calving. Two hundred thirty-three heifers were included in the study. At the initial sampling, 56.5% of quarters were infected with some type of organism and 15.4% of quarters were infected with Staphylococcus aureus. Treatments included a cephapirin dry cow product, a penicillin-novobiocin dry cow product, a penicillin-streptomycin dry cow product, an experimental dry cow product containing tilmicosin, and a cephalonium dry cow product not available in the United States. Cure rates for the five antibiotic products indicated that all were equally effective against Staph. aureus and all were significantly more effective than the spontaneous cure rate observed in untreated control quarters. No differences in efficacy were observed due to the different treatment times prepartum. However, fewer new Staph. aureus infections occurred after treatment in the group treated at 180 to 270 d prepartum, indicating that treatment in the third trimester will reduce the chances of new intramammary infections occurring after treatment and persisting to calving.

Efficacies of chlorine dioxide and lodophor teat dips during experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

We tested two postmilking teat dips for efficacy against Staphylococcus aureus and Streptococcus agalactiae using experimental challenge procedures recommended by the National Mastitis Council. The chlorine dioxide teat dip that contained 0.7% sodium chlorite reduced the number of new intramammary infections (IMI) caused by Staph. aureus by 86.6% and reduced new IMI caused by Strep. agalactiae by 88.4%. The 0.5% iodophor teat dip reduced the number of new IMI caused by Staph. aureus by 92.9% and reduced the number of new IMI caused by Strep. agalactiae by 43.4%. Teat skin and teat end conditions were evaluated before and after the study, and no deleterious effects were noted among dipped quarters compared with undipped control quarters for either teat dip.

Germicidal activity of a chlorous acid-chlorine dioxide teat dip and a sodium chlorite teat dip during experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

Three postmilking teat dips were tested for efficacy against Staphylococcus aureus and Streptococcus agalactiae in two separate studies using experimental challenge procedures that were recommended by the National Mastitis Council. The first study evaluated a barrier teat dip product containing chlorous acid-chlorine dioxide as the germicidal agent, and the second study evaluated a sodium chlorite product with a barrier component as well as a sodium chlorite product without a barrier component. The chlorous acid-chlorine dioxide teat dip reduced new intramammary infections (IMI) caused by Staph. aureus by 91.5% and reduced new IMI caused by Strep. agalactiae by 71.7%. The barrier dip containing sodium chlorite reduced new IMI caused by Staph. aureus and Strep. agalactiae by 41.0 and 0%, respectively. The nonbarrier dip containing sodium chlorite reduced new IMI caused by Staph. aureus by 65.6% and reduced new IMI caused by Strep. agalactiae by 39.1%. Teat skin and teat end conditions were evaluated before and after the second study; no deleterious effects among dipped quarters compared with control quarters were noted for the two sodium chlorite products.

Efficacies of teat germicides containing 0.5% chlorhexidine and 1% iodine during experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

Two germicides, one containing 0.5% chlorhexidine and one containing 1% iodine, were tested for efficacy against new intramammary infections (IMI) caused by Staphylococcus aureus and Streptococcus agalactiae. The model for the experimental challenge in the trials that were designed to test the efficacy of the two postmilking teat dips was recommended by the National Mastitis Council. The 0.5% chlorhexidine product reduced the number of new IMI caused by Staph. aureus by 73.2% and reduced the number of new IMI caused by Strep. agalactiae by 53.9%. The 1% iodine product reduced the number of new IMI caused by Staph. aureus by 75.6% and reduced the number of new IMI caused by Strep. agalactiae by 53.5%. In both trials, the incidence of clinical mastitis was also reduced in dipped quarters compared with control quarters. Use of the two teat dips over the trial periods had no effect on the condition of teat skin or teat ends.

Evaluation of two iodophor teat germicides: activity against Staphylococcus aureus and Streptococcus agalactiae.

Two germicides containing 0.5 and 1% titratable iodine were tested for efficacy against the development of new intramammary infections (IMI) caused by Staphylococcus aureus and Streptococcus agalactiae. The two trials for postmilking teat dip used a model for experimental challenge that was recommended by the National Mastitis Council. The 0.5% iodine formulation reduced new Staph. aureus IMI by 78.2% and reduced new Strep. agalactiae IMI by 73.2%. The 1% iodine product reduced new Staph. aureus IMI by 43.5% and reduced new Strep. agalactiae IMI by 46.4%. No adverse effects on the condition of teat skin or on teat ends were observed over the course of the trials. At the completion of each trial, the teat skin of dipped quarters was characterized as normal, smooth skin that was free from scales, cracks, or chapping; the teat orifice was characterized as smooth without evidence of irritation.

Efficacy of teat dips containing a hypochlorous acid germicide against experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

Two teat dip formulations containing sodium dichloroisocyanurate, which released hypochlorous acid (2800 ppm) as the active ingredient, were tested for efficacy against new Staphylococcus aureus and Streptococcus agalactiae IMI using an experimental challenge model. Product 1 reduced the number of new Staph. aureus IMI by 73.6% and reduced the number of new Strep. agalactiae IMI by 65.1%. Product 2 reduced the number of new Staph. aureus IMI by 69.0% and reduced the number of new Strep. agalactiae IMI by 63.5%. No adverse effects on teat skin condition were observed over the course of the studies.

Efficacy of barrier-type postmilking teat germicides against intramammary infection.

Two barrier teat dips were evaluated for efficacy in preventing new IMI by Staphylococcus aureus and Streptococcus agalactiae during experimental exposure trials, and two barrier dips were evaluated during natural exposure trials. Dipping in an experimental product containing nicin as a germicide using experimental exposure demonstrated no difference in rate of new Staph. aureus IMI (10.2%) compared with that of controls (7.1%) or in the rate of new Strep. agalactiae IMI (13.6%) compared with that of controls (11%). Testing of an experimental .55% chlorhexidine gluconate barrier dip using experimental exposure resulted in an increased rate of new Staph. aureus IMI compared with that of controls (4.8 vs. 1.7%, respectively), but no difference in the rate of new Strep. agalactiae IMI in dipped quarters (6.1%) compared with that of controls (3.3%). Dipping with a commercial .3% iodine barrier dip during natural exposure increased the number of new coagulase-negative staphylococcal and total IMI by 56.6 and 30.6%, respectively, compared with a 1% iodophor dip without barrier. Use of an experimental .3% iodine barrier dip during natural exposure demonstrated no difference in total rate of new IMI (18.4%) compared with that of controls (20.3%); however, after germicide concentration was increased to .5% iodine and further tested, the reformulated product reduced new IMI by 43.1%. Under the conditions of these trials, the barrier teat dips tested were no more efficacious than no teat dip or using a nonbarrier product.

Mastitis in dairy heifers: initial studies on prevalence and control.

Initial studies to determine the prevalence of mastitis in heifers of breeding age and in pregnant dairy heifers demonstrated that IMI were present in 97% of heifers and 75% of quarters. The most common isolates were Staphylococcus aureus, Staphylococcus hyicus, and Staphylococcus chromogenes; SCC ranged from 12.4 to 17.3 x 10(6)/ml. Approximately 29% of heifers and 15% of quarters exhibited clinical mastitis at breeding age, as evidenced by clots or flakes in mammary secretions. Histologic examination of mammary tissues demonstrated significant reductions in alveolar epithelial and luminal areas and increases in connective tissue stroma and leukocytosis, illustrating limited development and marked inflammation of infected tissues. A one-time infusion of antibiotic for nonlactating cows into infected quarters > or = 45 d prepartum reduced incidence of IMI by 59% at calving compared with the pretreatment level; the cure rate for Staph. aureus IMI was > 90%. Prophylactic treatment of uninfected quarters > or = 45 d prepartum reduced new Streptococcus sp. IMI by 93%. The mean SCC was 50% lower at calving for treated heifers, and milk yield over the first 2 mo of lactation was 10% greater than that of untreated controls. Heifers from herds using fly control had a lower prevalence of IMI than herds without fly control. Prevalences of IMI and SCC in dairy heifers were higher than previously realized, but mastitis at calving was controlled by use of therapeutic products for nonlactating cows during pregnancy.

Efficacy of two barrier teat dips containing chlorous acid germicides against experimental challenge with Staphylococcus aureus and Streptococcus agalactiae.

Two postmilking teat dips were tested for efficacy against Staphylococcus aureus and Streptococcus agalactiae using experimental challenge procedures recommended by the National Mastitis Council. Both dips contained chlorous acid as the primary germicidal agent and lactic acid or mandelic acid as the chlorous acid activator. The dip activated with mandelic acid significantly reduced new IMI by Staph. aureus and Strep. agalactiae. The IMI rate was reduced 68.7% for Staph. aureus and 56.4% for Strep. agalactiae. The dip activated with lactic acid significantly reduced new Staph. aureus IMI by 69.3% but did not significantly reduce new Strep. agalactiae IMI (35.2% reduction) through the full 11-wk study period. Teat skin condition did not change from pretrial status after using either teat dip during the study.

Effect of naturally occurring coagulase-negative staphylococcal infections on experimental challenge with major mastitis pathogens.

The influence of pre-existing Staphylococcus sp. IMI on development of new IMI after experimental challenge with Staphylococcus aureus and Streptococcus agalactiae was studied. The IMI data were analyzed from five trials in which quarters were challenged with major pathogens incident to studies of teat dip efficacy. Prior to each trial, quarter IMI status was determined, and new IMI were enumerated during challenge. Percentage of new Staph. aureus IMI in uninfected quarters was 3-fold that of quarters already infected with Staphylococcus sp. Of quarters that were initially uninfected, 13.23% acquired new Staph. aureus IMI, and 4.49% of quarters infected with Staphylococcus sp. became infected. Conversely, the percentage of new Strep. agalactiae IMI in quarters infected with Staphylococcus sp. was 1.5-fold that of uninfected quarters (8.38 vs. 5.52%). The percentage of clinical Staph. aureus IMI in uninfected quarters was higher than for quarters infected with Staphylococcus sp., but percentages of clinical Strep. agalactiae IMI were similar among IMI statuses. Geometric mean SCC prior to challenge were 87 x 10(3) for uninfected quarters and 260 x 10(3)/ml for quarters infected with Staphylococcus sp. Quarters infected with Staphylococcus sp. were less susceptible to Staph. aureus IMI, but more susceptible to Strep. agalactiae IMI.

Effect of a Staphylococcus aureus bacterin on serum antibody, new infection, and mammary histology in nonlactating dairy cows.

The influence of a Staphylococcus aureus mastitis vaccine on immunologic status and rate of new IMI was evaluated. At drying off, cows were vaccinated, either intramuscularly or subcutaneously in the area of the supramammary lymph node, or were left as unvaccinated controls; vaccinates received booster injections at 6 wk. Serum antibody concentrations, bacteriologic status, and SCC of quarter milk samples were determined. Four weeks after revaccination, cows were challenged by intramammary infusion of S. aureus and then killed 24 to 72 h later. Mean serum antistaphylococcal antibody titer of vaccinated cows during the trial was 4.7-fold that of controls. Challenge resulted in IMI rates of 92, 36, and 60% for control cows, cows vaccinated intramuscularly, and cows vaccinated in the area of the supramammary lymph node. Vaccination by either route had no influence on mammary parenchymal tissue components compared with controls; however, leukocyte infiltration was greater in quarters from cows vaccinated in the area of the supramammary lymph node than in quarters from unvaccinated controls. Plasma cell populations producing IgG1, IgG2, IgA, and IgM were greatest in quarters of cows vaccinated in the area of the supramammary lymph node followed by those in quarters of cows vaccinated intramuscularly and control cows.

The effect of chronic immunostimulation of the nonlactating bovine mammary gland with interleukin-2, pokeweed mitogen, and lipopolysaccharide.

Interleukin-2, pokeweed mitogen, and lipopolysaccharide were evaluated for their ability to accelerate involution and to stimulate local cellular defenses in the nonlactating bovine mammary gland. Twelve cows were divided into three treatment groups of 4 cows each to receive interleukin-2, pokeweed mitogen, or lipopolysaccharide. One day after drying off, 3 mammary quarters of each cow were infused with 100 micrograms of immunostimulant daily for 21 d; the remaining control quarter received PBS. Secretion samples were collected weekly to determine bacteriologic status, total SCC, and differential cell counts. On d 21, cows were killed, and tissues were collected for microscopy. Overall, SCC were higher in immunostimulated quarters, but only those infused with interleukin-2 were significantly elevated over controls. By wk 3, the percentage of neutrophils decreased in interleukin-2 and pokeweed mitogen quarters over pretreatment values, percentage of macrophages increased in interleukin-2 quarters, and percentage of lymphocytes increased in pokeweed mitogen and lipopolysaccharide quarters. Percentage of alveolar lumina was reduced, and connective tissue stroma increased, in all immunostimulated quarters compared with those of controls, suggesting accelerated involution. Involution was greatest in quarters treated with interleukin-2. Leukocyte infiltration was greater in immunostimulated quarters than in control quarters. Similarly, concentrations of Ig-producing plasma cells were greater in immunostimulated quarters than in control quarters. Quarters infused with interleukin-2 exhibited the greatest concentration of plasma cells, followed by quarters treated with pokeweed mitogen and lipopolysaccharide; IgG1 plasma cells predominated, followed by IgG2, IgA, and IgM. Interleukin-2 accelerated involution and stimulated local antibody production more than did the two mitogens, suggesting a potential role for this cytokine as a general immunostimulant at drying off.

Evaluation of postmilking teat germicides containing Lauricidin, saturated fatty acids, and lactic acid.

The efficacies of postmilking teat germicides containing Lauricidin (glyceryl monolaurate), saturated fatty acids, lactic acid, and lauric acid were determined against new IMI caused by Staphylococcus aureus and Streptococcus agalactiae in three controlled infection trials. In trial 1, a germicide was evaluated containing 1% Lauricidin, 5% caprylic and capric acids, 6% lactic acid, and .85% lauric acid. New IMI with Staph. aureus and Strep. agalactiae were reduced 81.3 and 49.6%, respectively. Trial 2 germicide involved an artificially aged sample of the formulation evaluated in trial 1. The germicide was aged at 40 degrees C for 5 mo, which was approximately equal to 2 yr at room temperature (24 degrees C). Reductions in new IMI were 81.2 and 27.5% for Staph. aureus and Strep. agalactiae, respectively. In trial 3, a teat germicide aged at ambient temperature for 33 mo, which was originally formulated to contain 1% Lauricidin, 5% caprylic and capric acids, and 6% lactic acid, was evaluated. Reductions in new IMI were 75.5 and 40.4% for Staph. aureus and Strep. agalactiae, respectively. The formulation evaluated in trial 1 was superior to other formulations in reducing new IMI by the two test organisms.

Effects of a 1.94% sulfonic acid teat dip and a 1% iodophor teat dip on teat canal infections in lactating dairy cows.

Sixty-three cows were used in a natural exposure trial for 1 yr to determine the effects of a 1.94% linear dodecyl benzene sulfonic acid and a 1% iodophor teat dip on teat canal and intramammary infections. Overall, total teat canal infections increased 28.9% and total intramammary infections increased 30% in quarters dipped with the linear dodecyl benzene sulfonic acid compared with a 14.3% increase in teat canal infections and a 17.4% decrease in intramammary infections for the iodophor group. Higher frequencies were observed for teat canal and intramammary infections caused by Staphylococcus epidermidis in the linear dodecyl benzene sulfonic acid group. Staphylococcus hyicus was the predominant organism isolated from teat canal and intramammary infections in the iodophor group. No difference was observed between the two teat dips in the persistence of Staphylococcus aureus teat canal infections. A greater number of S. hyicus teat canal infections persisted in the iodophor group, whereas teat canal infections produced by S. epidermidis and Staphylococcus xylosus persisted longer in the sulfonic acid group. Results of this study indicated that use of a linear dodecyl benzene sulfonic acid teat dip for 1 yr was not associated with increased S. aureus teat canal infections and intramammary infections. However, linear dodecyl benzene sulfonic acid appeared to affect the distribution of coagulase-negative staphylococci isolated from teat canal infections and intramammary infections.

Effects of novel intramammary device models on incidence of mastitis after experimental challenge.

First-calf heifers were fitted with five different intramammary device models prior to, or within 2 mo after parturition. Each model represented an increase in the weight of the device to be supported by the epithelial cells of the gland cistern. Each model was tested in four animals by placing devices in two quarters while remaining quarters served as controls. Foremilk and stripping quarter secretion samples were collected prior to device placement and weekly thereafter and analyzed for total and differential cell counts, bacteriologic status, and NAGase activity. During the prebacterial challenge treatment period, foremilk and stripping SCC as well as percentage of neutrophils and NAGase activity in most device-fitted quarters remained significantly elevated over controls. Frequency of naturally occurring intramammary infection during the prechallenge period was lowest in quarters fitted with Models 2, 4, and 5. Frequency of infection with coagulase-negative staphylococci also tended to be lower in quarters fitted with Models 2, 4, and 5. Approximately 4 mo after device placement, all quarters were challenged by intracisternal inoculation with about 565 cfu Streptococcus uberis. Results across all models combined showed that although mean foremilk and striping SCC and percentage of neutrophils were significantly elevated in device-fitted quarters immediately prior to bacterial challenge, only Model 4 showed a protective effect. Several models were superior to others in elevating SCC and percentage of neutrophils, but no differences in susceptibility to Strep. uberis infection were observed among models based on these cytological characteristics.

Efficacy of two iodophor postmilking teat germicides against Streptococcus agalactiae.

Two iodophor teat germicides containing .1% and .5% titratable iodine were subjected to experimental challenge with Streptococci agalactiae in a 131-cow research herd. Both germicides reduced the number of new infections with challenge organisms during a 5-wk study. The .1% iodophor reduced the new infection rate 60.7%, and the .5% iodophor reduced the new infection rate 61.5%. Teat skin irritation and other teat abnormalities were not observed.