Efficacy of an iodophore teat disinfectant against Staphylococcus aureus and Streptococcus agalactiae in experimental challenge

A 1.0% iodophore teat disinfectant (Full-Bac) was evaluated in comparison with a positive control (Bovadine), a commercially available 1.0% iodophore teat disinfectant. The study was conducted under conditions of experimental challenge, following the guidelines recommended by the National Mastitis Council. The test product and a positive control were compared in 41 cows, with 82 teats receiving each product at milking, during a 10-wk study period. There were no differences between the test product and the positive control in new intramammary infections due to Staphylococcus aureus, which averaged 13.4% in each of the 2 treatment groups. Additionally, no statistical difference was seen between the test product and positive control in new intramammary infections by Streptococcus agalactiae, which averaged 8.5 and 6.1% for the Full-Bac and Bovadine groups, respectively. Teat skin and teat end condition scores were statistically evaluated at wk 1, 5, and 9 of the study, and no significant differences were observed between the treatment groups. The test teat disinfectant provided similar germicidal activity to that of the positive control teat disinfectant with no adverse effects on teat skin or teat end condition during the warm-season study period.     

Evaluation of a postmilking teat disinfectant containing a phenolic combination for the prevention of mastitis in lactating dairy cows

A trial was conducted for 12 months in a herd of 120 Holstein cows in order to determine the efficacy of a teat disinfectant, which contained a phenolic combination, for the prevention of bovine intramammary infections during lactation. Postmilking teat disinfection was compared to a negative control using a split-udder experimental design. The percentage of quarters newly infected by mastitis pathogens was 45% lower in mammary glands with teats that had been dipped in the experimental teat disinfectant after milking than it was in undipped controls. New infections caused by Streptococcus uberis, Staphylococcus aureus, coagulase-negative Staphylococcus species, and Corynebacterium bovis were significantly lower in mammary glands with teats that had been dipped in the experimental teat disinfectant than in undipped controls. No statistical differences in the incidence of clinical mastitis between treatment groups were observed. No irritation or chapping of teats dipped in the experimental teat disinfectant were observed. The results of this study suggest that the experimental teat disinfectant containing a phenolic combination is an effective postmilking teat disinfectant for use in the prevention of new intramammary infections by both contagious and environmental mastitis pathogens.     

Short communication: disinfectant containing a complex of skin conditioners

The efficacies of 2 new teat dip formulations were tested against experimental challenge by contagious mastitis pathogens Staphylococcus aureus and Streptococcus agalactiae over a 12-wk period. Formulations contained an iodine complex (0.5 or 1.0% iodine) and skin conditioning agents (propylene glycol, polyvinylpyrridone, glycerine, lanolin, allantoin, and aloe). Percentage reduction (dipped vs. control mammary quarters) in new contagious mastitis pathogen intramammary infections for the 0.5 and 1.0% iodine dips was 65.4 and 84.5, respectively. Both dips were significantly effective in reducing new contagious intramammary infections. Teat skin scores and teat end scores varied over time but were virtually identical for both treated and control teats, for both treatments. Thus, both dips were effective in reducing new contagious mastitis infections without untoward effects on teat skin condition.     

Noninferiority trial on the efficacy of premilking teat disinfectant against naturally occurring new intramammary infections using a novel 2-step diagnostic process

The objective of the study was to evaluate premilking teat disinfectant efficacy with the use of a novel diagnostic protocol against a positive control. The evaluation of efficacy was based on establishing noninferiority of a new premilking teat disinfectant compared with an existing premilking teat disinfectant. Approximately 200 cows were randomly allocated to 1 of 2 groups. Study personnel were blinded as to cow allocation and identification of the premilking disinfectants. Quarters were disinfected using a dip cup before milking with either the control or experimental product. The disinfectant was left on the teat for approximately 30 s before being wiped off in preparation for milking. Quarter-level bacteriological infection status was established at the beginning of the study and quarter milk samples were collected biweekly thereafter. Bacteriological analyses were performed only when somatic cell counts in milk samples crossed a parity-specific threshold. Poisson regression models were used to analyze data. The difference in the rate of new intramammary infections was small and the upper bound of the 95% confidence interval of the rate difference was smaller than a predefined noninferiority limit. Based on the observed difference in new intramammary infections rate between the experimental and control product, it was concluded that the experimental disinfectant was not inferior compared with the positive control. The protocol used in this study proposes a valid and economically attractive methodology to evaluate the efficacy of teat disinfectants relative to a positive control.     

Efficacy of chlorhexidine as a postmilking teat disinfectant for the prevention of bovine mastitis during lactation

A natural exposure trial was conducted for 12 mo in a herd of 150 lactating Jersey cows to determine efficacy of a .35% chlorhexidine teat dip containing a glycerine emollient for the prevention of bovine intramammary infections. Right teats of cows were dipped in the experimental teat dip after milking machine removal and left teats were not dipped. The herd was free of Streptococcus agalactiae and had a low prevalence of Staphylococcus aureus. Most new major pathogen intramammary infections resulted from Streptococcus species, primarily Streptococcus uberis and Streptococcus dysgalactiae. New infections by Streptococcus species were significantly lower in teats dipped in chlorhexidine than in undipped teats. Overall efficacy of the chlorhexidine teat dip against major mastitis pathogens was 50%. The experimental teat dip also reduced coagulase-negative Staphylococcus species infections 49.0% and Corynebacterium bovis infections 65.2%. Overall efficacy against minor mastitis pathogens was 54.0%. No irritation or chapping of teats dipped in the experimental teat dip was observed.     

Colonization by Staphylococcus aureus on chapped teat skin: effect of iodine and chlorhexidine postmilking disinfectants.

The abilities of common postmilking teat disinfectant solutions and a teat skin ointment to retard Staphylococcus aureus colonization and promote healing of chapped skin were studied. Ten Holstein cows, free of S. aureus intramammary infections and mammary epidermal colonization, were used. All teats were experimentally chapped with 1N sodium hydroxide and dipped in S. aureus broth culture of 5 x 10(6) cfu/ml after three consecutive milkings. Postmilking teat disinfectant treatments were applied, starting after the second application of S. aureus broth culture, and were continued for the next 19 milkings. Quarters of each cow received one of the following postmilking teat treatments: 1% iodine plus 10% glycerin solution; .5% chlorhexidine plus 4.87% glycerin solution; 1% chlorhexidine ointment; and no postmilking treatment. After milking and before treatment application, samples of skin swabbings of the teat end and teat side and samples of milk were collected. Daily teat skin chapping visual scores were made to assess chapping and healing. Teat skin chapping decreased with time, and the decline was similar among treatments. The concentration of S. aureus recovered from teat skin swabbing solutions decreased over time. Staphylococcus aureus were recovered at significantly lower concentrations from swabbing solutions of teats that were dipped with iodine and chlorhexidine solutions as compared with untreated teats. Staphylococcus aureus was in marginally higher concentrations on ointment-treated teats than on dipped teats. Results indicate the importance of using postmilking teat dips on chapped teats and suggest no advantage in applying a disinfectant ointment to chapped teats to reduce S. aureus colonization and improve skin healing.     

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.     

Randomized noninferiority field trial evaluating a postmilking teat dip for the prevention of naturally occurring intramammary infections

The aim of this study was to perform a positive-controlled field study under natural exposure conditions to test the efficacy of a newly developed chlorine dioxide-based postmilking teat disinfectant (experimental product, EX) for noninferiority compared with an already established chlorine dioxide-based teat disinfectant (positive control product, PC). After blocking by parity, approximately 200 Holstein cows in early to mid-lactation stages from a dairy farm near Padua, Italy, were randomly assigned to one of 2 groups. Over a 13-wk period between September and December 2021, the teats of cows were dipped with the EX or the PC after each milking. Milk samples were collected from individual quarters of enrolled cows for 13 wk to determine infection status. Teat condition was assessed at wk 1, 5, and 9. Mixed logistic regression was used to analyze the effect of treatment on the incidence of new intramammary infections. For the noninferiority analysis, the upper limit of the 95% confidence interval for the difference in new intramammary infection (NIMI) rate between the 2 treatments (EX − PC) had to be to the left of the critical value d (0.035) to conclude that EX was noninferior to PC in terms of the risk of NIMI. The results showed that the incidence of new infections in the quarters treated with EX (3.1%) was not different from that in the udder quarters treated with PC (2.6%). No overall difference was found between the treatments in terms of teat condition. As the upper limit of the 95% confidence interval of the NIMI rate difference was smaller than the predefined noninferiority limit, we concluded that the EX was noninferior compared with the PC.     

Efficacy of two acidified chlorite postmilking teat disinfectants with sodium dodecylbenzene sulfonic acid on prevention of contagious mastitis using an experimental challenge protocol

Two acidified sodium chlorite postmilking teat disinfectants were evaluated for efficacy against Staphylococcus aureus and Streptococcus agalactiae by using National Mastitis Council experimental challenge procedures. The effect of these teat dips on teat skin and teat end condition was also determined. Both dips contained 0.32% sodium chlorite, 1.32% lactic, and 2.5% glycerin. Dips differed in the amount of sodium dodecylbenzene sulfonic acid (0.53 or 0.27%) added as a surfactant. Both dips significantly reduced new intramammary infection (IMI) rates compared with undipped controls. The dip containing 0.53% dodecylbenzene sulfonic acid reduced new IMI by Staph. aureus by 72% and Strep. agalactiae by 75%. The dip containing 0.27% dodecylbenzene sulfonic acid reduced new IMI by Staph. aureus by 100% and by Strep. agalactiae by 88%. Changes in teat skin and teat end condition for treatment and control groups varied in parallel over time. Teats treated with either teat dip had higher mean teat skin and teat end scores than control teats at some weeks. However, teat skin and teat end condition did not tend to change from the start to the completion of the trial. Application of the two new postmilking teat dips was effective in reducing new IMI from contagious mastitis pathogens. (Key words: teat dip, contagious mastitis, chlorous acid)     

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.     

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.     

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.     

Prevention of bovine mastitis by a postmilking teat disinfectant containing chlorous acid and chlorine dioxide in a soluble polymer gel

A natural exposure study was conducted in a herd of 150 lactating dairy cows for 18 mo to determine the effectiveness of chlorous acid and chlorine dioxide in a soluble polymer gel as a postmilking teat disinfectant for the prevention of bovine mastitis. Right quarters of cows were dipped in the experimental teat dip after milking machine removal. Left quarters were not dipped and served as within-cow negative controls. The experimental teat dip reduced Staphylococcus aureus infections 67.4%, Streptococcus dysgalactiae infections 63.8%, and Streptococcus uberis infections 27.8%. Overall efficacy of the chlorous acid and chlorine dioxide teat dip against major mastitis pathogens was 52.2%. The experimental teat dip reduced Corynebacterium bovis infections and coagulase-negative staphylococcal infections also by 45.8 and 38.7%, respectively. Overall efficacy against minor mastitis pathogens was 43.4%. Under conditions of this trial, the experimental teat dip containing chlorous acid and chlorine dioxide was effective in preventing new intramammary infections against a variety of mastitis pathogens.     

Preventing bovine mastitis by a postmilking teat disinfectant containing acidified sodium chlorite

A split-herd study was performed to determine if an acidified, sodium chlorite teat disinfectant, UDDERgold Platinum Germicidal Barrier Teat Dip (UG Pt, Ecolab Inc., Redmond, WA), was effective in preventing new intramammary infections (IMI) in lactating dairy cows compared with a licensed, iodophor teat disinfectant (Iosan, Novartis Animal Health, Ltd., Whittlesford, UK), and to show that the test product was tolerated equally well by teat skin. The study lasted 114 d and covered all weather conditions. The teats of 176 cows were dipped after each milking in UG Pt and the teats of 172 cows were dipped in Iosan, the positive-control product. Routine milk samples were taken from each quarter of every cow every 4 wk. Additional samples were taken from newly calved cows joining the trial and from cows with clinical signs of mastitis. Milk samples were cultured for the presence of bacteria and the cause of clinical mastitis. Each quarter was eligible for only 1 infection during the trial. The number of clinical cases was identical in each group (n = 13) and the number of subclinical infections was slightly lower in the UG Pt group than in the Iosan group (n = 27 and 31, respectively). These rates of infection suggest that the products did not differ in their ability to prevent a new IMI. At least 203 cows were assessed for skin integrity before the start of the trial and every 28 d throughout. The UG Pt teat dip had no adverse effects on teat condition. The prevalence of hyperkeratosis did not change with time for both groups (0.90 ± 1.08 and 0.95 ± 1.06 at wk 0 vs. 0.65 ± 0.87 and 0.49 ± 0.74 at wk 16 for fore and hind teats, respectively, for UG Pt and 1.02 ± 1.25 and 1.16 ± 1.11 at wk 0 vs. 0.51 ± 0.71 and 0.45 ± 0.65 at wk 16, respectively, for Iosan); no redness of the skin was observed in either group. Application of recommended statistical methods to demonstrate noninferiority was problematic.     

A review of test protocols for the evaluation of teat disinfectants

The prevention of mastitis is the most important part of a mastitis control programme. Postmilking disinfection is considered the most effective procedure for preventing new intramammary infections in dairy herds. This article reviews the different protocols used to evaluate the efficacy of teat disinfectant products. These protocols include experimental challenge, natural exposure and excised teat, along with agar diffusion assays and teat swabbing. The experimental designs, limitations, positive and negative aspects of each protocol were compared and discussed throughout this article.     

Efficacy of .18% iodine teat dip against Staphylococcus aureus and Streptococcus agalactiae

Effective postmilking teat dip products with lower iodine concentrations are being formulated as concern increases about iodine residues in milk. Increased free iodine concentration with greater germicidal activity in teat dip products is also possible with special formulation procedures. Low iodine concentration dips are cheaper and have reduced teat irritation. A concentrated iodine teat dip containing .18% iodine and 8 ppm free iodine upon dilution was evaluated under experimental bacterial challenge to determine efficacy for prevention of new intramammary infections. The undiluted product also contained 15% collagen protein emollient as a teat skin conditioner. Efficacy of the teat dip was 93.6 and 51. 7% for Staphylococcus aureus (Newbould 305) and Streptococcus agalactiae (McDonald 44). No adverse effects of the dip on teat skin were noted.     

Cleanliness scores as indicator of Klebsiella exposure in dairy cows

This study was designed to explore the relationship between cow and udder cleanliness scores and the risk of isolation of Klebsiella spp. from lower hind legs and teat ends, respectively. The distribution of Klebsiella species was compared among isolates from teat ends, legs, and cases of clinical mastitis obtained from 2 dairy farms in New York State, with 850 and 1,000 cows, respectively. Farms were visited twice approximately 4 wk apart in August and September 2007 to obtain cleanliness scores and swabs from legs and teats. Isolates of Klebsiella clinical mastitis from each farm were collected from July through October 2007. Two studies were conducted. In the first study, whole-cow cleanliness of a purposive sample of 200 lactating cows was scored using a 4-point scale, and swabs were taken from their lower hind legs. In the second study, udder cleanliness of a separate convenience sample of 199 lactating cows was scored in the milking parlor, and swabs were taken from their teat ends before and after premilking udder preparation. Prevalence of Klebsiella spp. on legs and teat ends before udder preparation was 59 and 60%, respectively. Logistic regression was used to explore the association between isolation of Klebsiella spp. and cleanliness scores. Cow cleanliness scores and udder cleanliness scores were not associated with detection of Klebsiella on legs and on teats before udder preparation, respectively. After udder preparation, 43% of previously Klebsiella positive teat end samples remained positive, with significant differences between farms and months. Teats from dirty udders were significantly more likely to test positive for Klebsiella after udder preparation than teats from clean udders. The proportion of Klebsiella pneumoniae and Klebsiella oxytoca isolates was similar for isolates from teat end swabs and clinical mastitis cases, supporting the notion that the presence of Klebsiella on teat ends may lead to opportunistic intramammary infections. Udder cleanliness scores could be used as a management tool to monitor the risk of exposure to Klebsiella spp. on teat ends.     

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.     

Evaluation of udder preparations on intramammary infections

Udder preparations of wet towel plus drying and .1% iodophor premilking teat dipping plus drying were compared with no preparation to determine effects on number of new intramammary infections. Teats of 84 cows were challenged (5 d/wk) for 18 wk with a culture broth of Streptococcus uberis 3 h prior to each p.m. milking to stimulate environmental contamination. Wet towel plus drying and premilking teat dipping plus drying significantly reduced number of new intramammary infections compared to no preparation. Cleaning with water or dipping with a premilking teat dip and manual drying of teats may have contributed to the reduction in number of new infections. Premilking teat dipping plus drying further reduced number of new infections compared to use of wet towel plus drying. Apparently, teat dipping was more effective in reducing the number of new infections than water used with the wet towel. This study showed that udder preparations can affect udder health when an experimental bacterial challenge is applied.     

Efficacy of a high free iodine barrier teat disinfectant for the prevention of naturally occurring new intramammary infections and clinical mastitis in dairy cows

Using a natural exposure trial design, the goal of our study was to evaluate the clinical efficacy of an iodine teat disinfectant with barrier properties and a high level of free iodine relative to a conventional iodine teat disinfectant with no barrier properties and low levels of free iodine. During the 18 wk of the trial, quarter milk samples were collected every 2 wk from 385 dairy cows from 2 herds. Cows on both farms were assigned in a balanced way according to milk yield, number of lactation, days in milk, somatic cell count (SCC) and microbiology culture pretrial into one of following groups: nonbarrier post milking teat disinfectant (NBAR; n = 195 cows; 747 quarters) or barrier postmilking teat disinfectant (BAR; n = 190 cows; 728 quarters). Afterward, at each scoring date every 2 wk, milk SCC was quantified in samples from all mammary quarters and microbiologic culture was only performed on milk samples with SCC >200,000 cells/mL for multiparous cows and SCC >100,000 cells/mL for primiparous cows. A new intramammary infection (NIMI) was defined when a quarter had milk SCC <200,000 cells/mL for multiparous cows and <100,000 cells/mL for primiparous without microorganism isolation, and in a subsequent sampling visit had milk SCC >200,000 cells/mL for multiparous cows and >100,000 cells/mL for primiparous cows, and positive microorganism isolation. A quarter could have several NIMI, but only 1 case per specific pathogen was considered. The most frequently isolated microorganism group on both farms was Streptococcus spp. (6.25% of total mammary quarters), followed by coagulase-negative staphylococci (3.6%) and Corynebacterium spp. (1.5%). In the present study, an interaction occurred between treatment and week of trial on the incidence risk of NIMI. Quarters disinfected with BAR had 54 and 37% lower odds of NIMI than quarters disinfected with NBAR at 8 and 16 wk of the trial, respectively; whereas at other weeks of the study both products had similar incidence risks of NIMI. Overall, teats disinfected with BAR had 46% lower odds of acquiring a clinical mastitis than those disinfected with NBAR. We concluded that the postmilking teat disinfectant with barrier properties and higher free iodine content reduced the risk of clinical mastitis, although differences in new infections were detected at only weekly time points.