Development of a PCR amplification assay as a screening test using bulk milk samples for identifying dairy herds infected with bovine viral diarrhea virus

The approach of cDNA synthesis followed by polymerase chain reaction (PCR) amplification was used to develop a rapid screening test for the detection of bovine viral diarrhea virus (BVDV) in bulk tank milk samples. The initial development of this detection method was done using lactating Holstein cows; 1 acutely infected with BVDV following experimental inoculation and 2 persistently infected (PI) with BVDV. Viral RNA was extracted from somatic cells purified from whole milk using a guanidinium isothiocyanate and phenol/chloroform extraction method. Oligonucleotide primers were selected from the 5'untranslated region (5'UTR) and p80 region of BVDV genome. In the acutely infected cow, BVDV RNA was identified from days 6 to 10 postinoculation. Viral RNA extracted from somatic cells of milk from PI cows was detected by PCR using both 5'UTR and p80 primer sets. The sensitivity of PCR detection was determined by preparing dilutions of whole milk obtained from the BVDV persistently infected animals with milk from a BVDV-negative cow followed by purification of somatic cells and RNA extraction. BVDV was detected in milk serially diluted to 1:640 using PCR amplification. In addition, PCR amplification was 14.6 times more sensitive than virus isolation in detecting BVDV RNA in purified milk somatic cells. PCR detected BVDV RNA from a minimum of 580 somatic cells while the detection limit of virus isolation was 8500 cells. The sensitivity and specificity of BVDV amplification were confirmed by Southern hybridization analysis. BVDV RNA was detected using PCR in 33 out of 136 bulk milk samples collected from 124 individual herds using the 5'UTR primer set. These results indicate that PCR analysis of bulk tank milk samples may provide a rapid and sensitive method of screening herds for the presence of BVDV infections.

Effects of an Escherichia coli J5 vaccine on mild clinical coliform mastitis

Efficacy of an Escherichia coli (O111:B4) J5 bacterin was tested in an experimental challenge trial. Nineteen cows were vaccinated with an E. coli J5 bacterin, and 10 cows were injected with a placebo containing adjuvant only. Vaccine and placebo were administered at drying off, 30 d after drying off, and within 48 h after calving. Cows were challenged approximately 30 d after calving by intramammary infusion with a smooth heterologous strain of E. coli previously shown to cause mild clinical mastitis. Vaccination with the J5 bacterin reduced duration of IMI and local signs of clinical mastitis. Concentrations of BSA in milk 24 h after challenge were greater in control cows than in cows vaccinated with J5. The SCC at 7 d postchallenge were greater for cows vaccinated with the placebo than for cows vaccinated with J5. Bacterial counts were lower for cows vaccinated with the placebo than for cows vaccinated with J5 at 3, 6, and 9 h postchallenge. In contrast, cows vaccinated with J5 had lower bacterial counts at 2, 3, and 4 d postchallenge than did cows vaccinated with placebo. Systemic signs of clinical mastitis were relatively mild and similar between treatment groups. Rectal temperature, DMI, and milk production did not differ between control and cows vaccinated with J5 following challenge.

Efficacy of dry cow therapy and a Propionibacterium acnes product in herds with low somatic cell count

Dry cow therapy and a Propionibaterium acnes product were evaluated in four commercial herds with low SCC. Cows were randomly assigned within herds to treatment groups of approximately 90 cows receiving dry cow therapy, P. acnes, dry cow therapy plus P. acnes, or no treatment in a factorial arrangement. Each lactating quarter of cows that received dry cow therapy was infused via the teat duct with 300 mg of cephaprin at drying off. Cows that received P. acnes were infused intravenously with .4 mg of killed P. acnes at drying off, 7 to 10 d prepartum, and within 7 d after calving. A second prepartum injection of P. acnes immunostimulator was administered to cows that did not calve within 10 d after the first prepartum injection. Dry cow therapy enhanced bacteriological cures of IMI by Staphylococcus aureus and Corynebacterium bovis at drying off. Dry cow therapy reduced incidence of new IMI by environmental streptococci and C. bovis that originated during the dry period. Cows treated with P. acnes alone had a greater incidence of new IMI by Gram-negative bacilli originating during the dry period than did cows in the other treatment groups. Incidence of clinical mastitis at calving was greater for cows receiving no treatment than for cows receiving dry cow therapy, P. acnes, or dry cow therapy plus P. acnes.

Effect of dietary fat and vitamin E on alpha-tocopherol and beta-carotene in blood of peripartum cows

Nonlactating cows were fed diets containing 88% grass forage and 12% concentrate (DM basis). Starting 14 d prior to anticipated calving, the concentrate was changed to provide 0 or 200 g of supplemental fat and 0 or 890 IU of supplemental vitamin E daily. Following parturition, cows were fed for 14 d a 50% concentrate diet that provided the same amounts of supplemental fat and vitamin E that were fed during the dry period. Plasma was sampled and analyzed for alpha-tocopherol and beta-carotene. Supplemental dietary fat elevated plasma concentrations of both nutrients during the peripartum period. Supplemental dietary vitamin E elevated concentrations of alpha-tocopherol during that period. Dietary fat also increased concentrations of plasma cholesterol. When alpha-tocopherol and beta-carotene were expressed per unit of plasma cholesterol, fat supplementation did not affect concentrations. Dietary treatments did not influence concentrations of alpha-tocopherol in blood neutrophils and did not affect intracellular kill of bacteria by neutrophils. Essentially no beta-carotene was found in the neutrophils. For colostrum, dietary vitamin E increased concentrations of alpha-tocopherol and decreased concentrations of beta-carotene.

Therapy of experimentally induced coliform mastitis with a Propionibacterium acnes product

The efficacy of a Propionibacterium acnes product for treatment of coliform mastitis was evaluated following intramammary infusion of Escherichia coli. Ten cows were injected intravenously with a product containing heat-killed P. acnes at 3 h, 3 d, and 7 d after bacterial challenge. Five cows served as untreated negative controls. Bacterial counts in milk, rectal temperatures, and milk SCC did not differ between treated cows and control cows. Intravenous infusion of P. acnes had no effect on milk production or DMI of treated cows compared with untreated controls. Therapy of experimentally induced coliform mastitis with a P. acnes product had no effect on severity or duration of clinical signs.

Environmental mastitis

Environmental mastitis affects all dairy farms and generally is the major mastitis problem on modern, well managed dairy farms. Control measures effective against contagious pathogens are of little value in controlling of environmental pathogens. Control of environmental mastitis is achieved by reducing exposure of teat ends to environmental pathogens and by maximizing the resistance of the cow to intramammary infection. Significant sources of environmental pathogens are organic bedding materials, manure covered alleyways, and wet or damp areas in barns, exercise lots, or pastures. Milking time hygiene can influence teat-end exposure. In general, exposure is minimized when all areas of the environment are clean, cool, and dry. Resistance is maximized by providing a stress-free environment that minimizes teat-end injury, and by feeding balanced diets sufficient in vitamin E and selenium. Antibiotic therapy during lactation or the dry period is of little value in the control of environmental mastitis in dairy herds, with the exception of preventing environmental streptococcal infection during the early dry period. Effective vaccines may help reduce the impact of environmental mastitis in the near future.

Role of vitamin E and selenium in host defense against mastitis

Vitamin E and Se are essential nutrients that share common biological activities. Deficiencies in either of these micronutrients have been related in increased incidence and severity of mastitis. A known physiological consequence of alpha-tocopherol or Se deficiency is reduced neutrophil activity. Vitamin E and the Se-containing enzyme, glutathione peroxidase, and antioxidants that protect neutrophils from the destructive action of toxic oxygen molecules necessary for intracellular kill of ingested pathogens. Dietary supplementation of cattle with Se results in a more rapid neutrophil influx into milk following intramammary bacterial challenge and increased intracellular kill of ingested bacteria by neutrophils. Dietary supplementation of early lactation cows with vitamin E results in increased bactericidal activity by bovine blood neutrophils. Recently completed trials have shown that subcutaneous injections of vitamin E approximately 10 and 5 d prior to calving successfully elevated neutrophil alpha-tocopherol concentrations during the periparturient period and negated the suppressed intracellular kill of bacteria by neutrophils that is commonly observed at calving.

Association of abnormal uterine discharge with new intramammary infection in the early postpartum period in multiparous dairy cows

The association of abnormal uterine discharge with the development of intramammary infection (IMI) was studied in 62 multiparous Holstein cows during the nonlactating period and from lactation days 3 through 30. Duplicate milk samples were obtained from each mammary gland at approximately day 30 of the nonlactating period. Milk samples for bacteriologic culture also were obtained from each gland from all cows at the end of the previous lactation, at parturition, and on a minimum of 7 additional dates during the first 30 days of lactation. Beginning after parturition and continuing once weekly for 4 weeks, each cow was examined, using a vaginal speculum to visually estimate the quantity of abnormal uterine discharge in the vagina. Additionally, uterine swab specimens were obtained for aerobic bacteriologic culture. Cows were allotted to groups on the basis of the maximal amount of abnormal uterine discharge observed at any 1 of the 4 examinations. Cows in group 1 had normal discharge or < 30 ml of abnormal discharge; in group 2, > or = to 30 ml of abnormal discharge, observed only on examination by vaginal speculum; and in group 3, > or = to 30 ml of abnormal discharge visible externally. A difference was not detected in the development of new IMI in the nonlactating period between cows that subsequently developed uterine discharge and those that did not. Although significant differences were not found, a tendency for lactating cows with abnormal uterine discharge to be at increased risk for developing new IMI was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth responses of coliform bacteria to recombinant bovine cytokines

Growth responses of 10 coliform isolates to recombinant bovine cytokines were measured in vitro. Six Escherichia coli and four Klebsiella pneumoniae isolates obtained from bovine IMI were tested for growth responses to recombinant bovine interleukin-1 beta, interleukin-2, and interferon-gamma. Cytokines were tested at 10(4), 10(3), 10(2), and 10 U/ml of media. Media used were a synthetic tissue culture medium, a chemically defined synthetic bacterial growth medium, and UHT sterilized milk. Bacterial counts in the synthetic tissue culture medium and UHT milk increased slightly as concentration of interferon-gamma in the media increased. Recombinant bovine interferon-gamma increased bacterial populations during the log growth phase but did not affect the number of bacteria in stationary growth phase. Bacterial growth responses were not related to either interleukin-2 or interleukin-1 beta concentrations in any of the three media. Bacterial growth responses to cytokines were not related to differences in either serum susceptibility, growth of isolates in dry cow secretion, duration of IMI from which isolates were obtained, or bacterial species.

Characteristics of coagulase-negative Staphylococci isolated from bovine intramammary infections

Coagulase-negative Staphylococci (CNS) isolated from 86 different bovine intramammary infections (IMI) were investigated for their plasmid content, antimicrobial resistance, and infection characteristics. Plasmids were isolated from 30.2% of CNS. Number of plasmid bands ranged from 1 to 5. With the exception of tetracycline resistance, the presence of plasmids was not related to antibiotic resistance. Staphylococcus chromogenes was the CNS most frequently isolated from bovine IMI. Intramammary infections were of long duration (mean = 222 days) and resulted in a low incidence of clinical mastitis (8.1% of IMI). The greatest percentage of IMI (55%) were detected in heifers with 57% of these IMI first detected at calving. A total of 56% of IMI originated during the dry period in second lactation or older cows. The number of plasmid-positive CNS IMI was greater (P < 0.05) in multilactational cows when compared to heifers. The presence of a plasmid-positive CNS had no influence on duration of IMI, origin of IMI, clinical status of the infection, and elimination of IMI.

Vitamin E as an adjuvant in an Escherichia coli J5 vaccine

Vitamin E was tested as an adjuvant in an Escherichia coli (O111:B4) J5 vaccine. Twenty cows were assigned to five groups of 4 cows. Cows in four groups were vaccinated with an E. coli J5 bacterin containing 5 ml of 10(9) boiled cells/ml. Vaccinations were at drying off, 30 d after drying off, and within 48 h after calving. Vaccine adjuvants differed among groups. The four treatment adjuvants were 5 ml of Freund's incomplete adjuvant, 5 ml of vitamin E, 2.5 ml of Freund's plus 2.5 ml of vitamin E, and 5 ml of PBS. Cows in the fifth group were unimmunized controls. A front mammary quarter of each cow was challenged by infusion of 10 micrograms of E. coli J5 lipopolysaccharide approximately 4 wk into lactation. Vitamin E alone enhanced serum IgM titers but had no effect on milk IgM or serum and milk IgG titers. The mixture of Freund's plus vitamin E resulted in peak IgG titers in serum and milk comparable with that of Freund's alone. Persistency of IgG titers in cows immunized with the Freund's plus vitamin E mixture was greater than the persistency of titers for cows immunized with the vaccine containing Freund's alone as the adjuvant. The mixture of Freund's plus vitamin E had a synergistic effect in reducing severity of systemic clinical signs.

Susceptibility of Escherichia coli isolated from intramammary infections to phagocytosis by bovine neutrophils

Thirteen Escherichia coli isolated from naturally occurring IMI were tested for susceptibility to phagocytosis by bovine blood neutrophils. Isolates were opsonized in pooled serum collected from nine healthy lactating cows. Bacteria isolated from IMI first diagnosed within 3 d after calving were more resistant to phagocytosis than were isolates from IMI originating during either the first half of the dry period or later during lactation. Duration of the IMI was negatively correlated with both phagocytic index and percentage of neutrophils phagocytizing within bacterial isolates from IMI originating at calving and during lactation. Phagocytosis was independent of duration of IMI within isolates from IMI originating during the first half of the dry period. Susceptibility to in vitro phagocytosis by neutrophils was not related to O antigen serotype, encapsulation, or growth in dry cow secretion.

Effect of supplementing periparturient cows with vitamin E on distribution of alpha-tocopherol in blood

Holstein cows were fed 0 or 1000 IU/d of supplemental vitamin E during the dry period and injected with placebo or 3000 IU of vitamin E at 10 and 5 d prior to anticipated calving. Blood was collected at various times, starting at 60 d prepartum (dry off) and concluding 30 d postpartum, and separated into plasma, red blood cells, and neutrophils. Oral supplementation increased concentrations of alpha-tocopherol in plasma and red blood cells on 10 d, but not on 5 d prepartum. Injection of vitamin E increased alpha-tocopherol in plasma, red blood cells, and neutrophils at d 5 prior to and on the day of parturition. Concentrations of alpha-tocopherol and cholesterol in plasma were correlated, and both were at their nadir at parturition. Concentrations of alpha-tocopherol in plasma and red blood cells were correlated, but the correlation increased when plasma alpha-tocopherol was expressed per unit of cholesterol. alpha-Tocopherol in plasma and neutrophils had a low correlation. Injection of alpha-tocopherol increased its concentration in plasma, red blood cells, and neutrophils during the periparturient period. Concentration of alpha-tocopherol in plasma of periparturient cows may be limited by its low lipid content, and transport mechanisms for alpha-tocopherol may differ between red blood cells and neutrophils.

Bovine neutrophil responses to parenteral vitamin E

Twenty-eight Holsteins were tested to determine effects of dietary and parenteral vitamin E supplementation during the dry period on plasma alpha-tocopherol and in vitro neutrophil functions at calving. Cows were assigned to one of four experimental groups receiving either supplemental dietary vitamin E, injections of vitamin E, both dietary and injections of vitamin E, or neither source of supplemental vitamin E during the dry period in a 2 x 2 factorial arrangement. Cows receiving parenteral vitamin E were injected subcutaneously with 3000 IU of vitamin E (dl-alpha-tocopherol) at 10 and 5 d prior to anticipated calving. Cows not receiving parenteral vitamin E were injected with a placebo. Experimental groups receiving dietary vitamin E during the dry period were supplemented with 1040 IU/d compared with none for controls. Cows injected with vitamin E had greater plasma alpha-tocopherol concentration 5 d after the first injection, at calving, and 1 wk after calving than did cows injected with placebo. Plasma alpha-tocopherol concentrations did not differ between dietary vitamin E treatment groups from calving through 4 wk postpartum. No interaction was found between dietary and parenteral supplementation of vitamin E on plasma alpha-tocopherol concentration. Neutrophils from cows injected with vitamin E had greater intracellular kill of bacteria at calving than did neutrophils from placebo-injected cows. Neither phagocytic index nor percentage of neutrophils phagocytizing differed between vitamin E-injected and placebo-injected cows. Dietary vitamin E during the dry period had no effect on neutrophil function at calving. Intracellular kill and plasma alpha-tocopherol were correlated at calving.

Efficacy of an Escherichia coli J5 mastitis vaccine in an experimental challenge trial

An Escherichia coli (O111:B4) J5 bacterin was tested for efficacy in reducing IMI and severity of clinical coliform mastitis in an experimental challenge trial. Ten cows were immunized at drying off, 30 d after drying off, and at calving. Ten control cows were not immunized. Right front quarters of all cows were infused with a heterologous strain of E. coli approximately 30 d after calving. Vaccinated cows had lower bacterial counts in milk and lower rectal temperatures than unvaccinated controls following intramammary challenge. Milk production and DMI were more depressed in controls than in vaccinated cows. Milk SCC did not differ between experimental groups. Mean serum IgG titer to whole cell E. coli J5 was significantly greater in vaccinated than in unvaccinated cows at 30 d after drying off, day of challenge, and 7 d postchallenge. Milk IgG titer to E. coli J5 was higher at challenge in vaccinated than in control cows. Vaccination with the E. coli J5 bacterin did not prevent IMI but did reduce severity of clinical signs following intramammary experimental challenge with a heterologous E. coli strain.

Opsonic activity of bovine serum and mammary secretion after Escherichia coli J5 vaccination

Six pairs of cows were used to determine the effects of immunization with an Escherichia coli (O111:B4) J5 bacterin on in vitro opsonization of a smooth heterologous strain of E. coli. One cow in each pair was either immunized with the vaccine or sham-immunized at drying off, 30 d after drying off, and at calving. Opsonizing bacteria with serum collected from vaccinated cows 21 d after calving resulted in higher mean number of intracellular bacteria per phagocytosing neutrophil than opsonizing bacteria with serum collected from control cows. Phagocytic parameters using serum collected at drying off and calving did not differ between treatment groups. A trend for enhanced opsonic activity of colostrum from vaccinates was noted. Enhanced opsonization by serum from vaccinated cows coincided with higher serum IgM titer to E. coli J5 whole cell antigen compared with controls. Serum IgG titers to E. coli J5 did not differ between groups. Colostrum IgG titers to E. coli J5 were greater at calving in vaccinated than in control cows. Colostrum and milk collected 21 d after calving from vaccinated cows had higher IgM titers to E. coli J5 than did mammary secretions from control cows. Numbers of intracellular bacteria per phagocytizing neutrophil were correlated positively with IgM titers to E. coli J5 in both serum and colostrum.

Field trial to determine efficacy of an Escherichia coli J5 mastitis vaccine

Efficacy of an Escherichia coli (O111:B4) J5 bacterin for preventing naturally occurring IMI and clinical mastitis was tested in a 2.5-yr field trial in a 225-cow commercial herd. Cows with odd-numbered identification were vaccinated, and cows with even-numbered identification served as unvaccinated controls for each lactation during the study. Immunizations were subcutaneous on the upper part of the rib cage just posterior to the scapula at drying off, 30 d after drying off, and at calving. Percentage of quarters infected at calving with Gram-negative bacteria did not differ between treatment groups. A total of 67% of Gram-negative bacterial IMI present at calving in control cows became clinical during the first 90 d of lactation compared with 20% in vaccinated cows. Rate of Gram-negative bacterial clinical mastitis was higher in control cows than in vaccinated cows during the first 90 d of lactation. Immunization with the E. coli J5 bacterin did not reduce level of Gram-negative bacterial IMI at calving but did reduce incidence of clinical mastitis.

Comparison of probiotic and antibiotic intramammary therapy of cattle with elevated somatic cell counts

The effects of treating subclinical mastitis with intramammary infusions of either a Lactobacillus or an antibiotic preparation on intramammary infection cure rate and on milk SCC were compared. Cows with two consecutive monthly DHIA composite SCC greater than 300,000 cells/ml (5.4771 log10/ml) were defined as high SCC cows. Twenty-six subclinical cows were randomly assigned to one of two treatments. Quarter foremilk samples were obtained from all quarters at d 0, 7, and 14 following infusion to determine the microbiological status and SCC. Composite milk SCC were determined monthly by DHIA and at d 0, 7, and 14 of the study. Coagulase-negative staphylococci were the predominantly isolated pathogens. Treatment of cows with Lactobacillus cured 21.7% of infected quarters, whereas 73.7% of infections treated with antibiotic were eliminated. Treatment of quarters with antibiotic did not reduce quarter SCC unless infected quarters were cured. Intramammary infusion of quarters with Lactobacillus increased quarter SCC, mainly because of an increase in SCC of initially uninfected, low SCC quarters. Monthly composite SCC were similar between treatments. The results indicate that administering Lactobacillus or antibiotic treatment to all quarters based on elevated composite SCC should not be adopted. Lactobacillus treatment increased SCC with no effect on infection rate.

Costs associated with selected preventive practices and with episodes of clinical mastitis in nine herds with low somatic cell counts

Nine dairy herds (mean size, 149 cows) with bulk-tank milk somatic cell counts of less than 300,000 cells/ml and greater than 80% of cows with Dairy Herd Improvement Association linear somatic cell counts less than or equal to 4 were selected for study. Each herd was monitored for 12 consecutive months. Duplicate quarter-milk specimens were collected from each cow for bacteriologic culturing at beginning of lactation, cessation of lactation, and at the time of each clinical episode of mastitis. Streptococcus agalactiae was never isolated and Staphylococcus aureus was isolated from less than 1% of all quarters. There were 554 episodes of clinical mastitis. During the year of study, the incidence rate of clinical mastitis varied from 15.6 to 63.7% of cows among the 9 herds. Mean costs per cow per year in herd for mastitis prevention were: $10 for paper towels, $3 for nonlactating cow treatment, and $10 for teat disinfectants. Mean cost associated with clinical mastitis was $107/episode. Approximately 84% ($90) of the costs attributed to a clinical episode were associated with decreased milk production and nonsalable milk. Costs of medication and professional veterinary fees per clinical episode varied significantly among the 9 herds. Three of the herds did not have a veterinarian treat a clinical episode of mastitis during the year of study even though 2 of these herds had the first and third highest incidence rates of clinical mastitis. When calculated on a per cow in herd basis, mean costs of $40/cow/year were attributed to clinical mastitis.(ABSTRACT TRUNCATED AT 250 WORDS)

Serratia species isolated from bovine intramammary infections

Intramammary infections from which Serratia spp. were isolated were studied over a 32-mo period in a research dairy herd consisting of approximately 120 lactating cows. A total of 29 Serratia spp. intramammary infections were detected and accounted for 9% of all Gram-negative bacterial intramammary infections. Serratia marcescens was the most common Serratia spp. isolated. Origin of intramammary infections was 48.3% during the first half of the dry period, 31% during the last half of the dry period, and 20.7% during lactation. A total of 64% of intramammary infections that were first detected during the first half of the dry period persisted to calving. Geometric mean number of lactation days infected for all infections was 55. Intramammary infections that originated during the first half of the dry period were present in lactation for a significantly greater number of days compared with intramammary infections new during the last half of the dry period or lactation. A total of 48% of infections were clinical. Serratia spp. intramammary infections tended to be of long duration compared with other Gram-negative bacterial intramammary infections and were highly associated with the dry period.

Antibodies to iron-regulated outer membrane proteins of coliform bacteria isolated from bovine intramammary infections

Expression of iron-regulated outer membrane proteins (OMP) by Escherichia coli and Klebsiella pneumoniae initially isolated from bovine intramammary infections (IMI) was investigated. Additionally, the presence of antibodies in bovine serum and mammary secretion directed against the iron-regulated OMP was examined. Outer membrane proteins were separated by sodium-dodecyl polyacrylamide electrophoresis. Detection of immunoglobulin G directed against OMP was by immunoblotting. All Gram-negative bacteria expressed iron-regulated OMP when grown in skim milk or trypticase soy broth plus iron chelator, alpha-alpha'-dipyridyl. Immunoglobulin G directed against the iron-regulated OMP, as well as the major OMP and several other proteins, was detected in serum and milk of lactating cows with or without Gram-negative bacterial IMI. Antibody against the iron-regulated OMP was detected also in colostrum, secretion from the involuted gland, and in newborn calf serum 4 days after ingesting colostrum.

Intramammary challenge with Escherichia coli following immunization with a curli-producing Escherichia coli

Holstein and Jersey cattle were immunized with a curli-producing strain of Escherichia coli (pCRL65/A012) or a noncurli-producing strain (pUC18/HB101) to determine differences in resistance to establishment of experimental intramammary infection. Cows (n = 6 per group) were immunized at 14 d prior to drying off, 7 d of involution, and at calving with 3 x 10(10) E. coli in Freund's Incomplete Adjuvant. At 30 d of lactation, one mammary quarter of each cow was infused with a wild strain of E. coli (727). Escherichia coli 727 was isolated from a naturally occurring intramammary infection and produced curli. All challenged quarters became infected, and all cows developed acute clinical mastitis. Geometric mean duration of intramammary infections was 6 d for both immunization groups. All infections were spontaneously eliminated within 10 d. No differences occurred between immunization groups in blood selenium and glutathione peroxidase activity, plasma selenium, number of E. coli 727 isolated from secretion after challenge, rectal temperature and SCC response, clinical status of mammary quarters, or DMI. Reduction in milk production after challenge was greater for cows immunized with E. coli pCRL65/A012. Immunization of dairy cattle with a curli-producing strain of E. coli did not protect against experimental intramammary challenge during lactation.

Gram-negative bacterial infections of the mammary gland in cows

Naturally acquired gram-negative bacterial intramammary infections (n = 160) were studied in 99 cows over a 2-year period. Escherichia coli, Klebsiella spp, Serratia spp, Enterobacter spp, and unidentified gram-negative bacteria were isolated from 28.8, 39.4, 9.4, 5.0, and 11.2%, respectively, of infected mammary glands. A majority (61%) of intramammary infections were first detected during the nonlactating period. Gram-negative bacteria isolated during the first half of the nonlactating period were predominantly Klebsiella spp, Serratia spp, and Enterobacter spp. Onset of E coli intramammary infections was more prevalent during the second half of the nonlactating period and during the first 7 days of lactation. The majority (59%) of infections were less than 28 days in duration, but Klebsiella spp and Serratia spp infections were of significantly (P less than 0.05) greater duration than infections with E coli. The greatest percentage (47%) of gram-negative bacterial intramammary infections were first detected during the summer.

Hemagglutination and hemolysis by Escherichia coli isolated from bovine intramammary infections

Seventy-six Escherichia coli isolated from bovine intramammary infections were tested for hemagglutination and hemolysis of erythrocytes. Fifty-seven percent of isolates were hemagglutination-positive for bovine erythrocytes compared with 46% that agglutinated guinea pig erythrocytes. Twenty-eight percent of isolates were hemagglutination-positive for erythrocytes from both species. Only 14.5 and 2.6% of isolates were mannose-resistant, hemagglutination-positive for bovine and guinea pig erythrocytes, respectively. Neither duration nor severity of infection from which isolates were obtained differed between isolates that were hemagglutination-positive and hemagglutination-negative. Percentage distribution of hemagglutination-positive isolates did not differ among isolates from infections that originated at calving, during lactation, or the first half of the dry period. Hemagglutination reactions were also not related to in vitro growth in cell-free dry cow secretion. Percent of isolates that caused hemolysis of washed bovine erythrocytes was 2.6% compared to 3.9% for sheep erythrocytes. Hemolysis was not related to hemagglutination. Hemagglutination and hemolysis of erythrocytes did not appear to be virulence factors for E. coli isolated from bovine intramammary infections.

Effect of duration of supplementation of selenium and vitamin E on periparturient dairy cows

Cows were fed diets either supplemented with .2 ppm Se and 70 IU vitamin E/kg diet DM (21 cows) or unsupplemented (40 cows) during the dry period (approximately 60 d). From parturition to 21 d of lactation, cows were fed diets that were either supplemented with .3 ppm Se and 40 IU/kg vitamin E or unsupplemented. At d 21 following parturition, 18 cows fed the unsupplemented diet were switched to diets containing 0 or .3 ppm supplemental Se and 0 or 40 IU/kg supplemental vitamin E arranged factorially. These diets were fed for the next 32 d. The remaining cows continued their respective diets for 32 d. Plasma Se concentrations averaged .1 microgram/ml for supplemented cows but were .05 micrograms/ml for unsupplemented cows. Plasma Se concentration from cows fed supplemental Se from 21 to 53 d postpartum increased rapidly and were not different from long-term supplemented cows. Whole blood glutathione peroxidase activity was lower in unsupplemented than in supplemented cows. Short-term Se supplementation increased glutathione peroxidase activity above that for unsupplemented animals, but activity was still less than that in long-term supplemented animals. Plasma alpha-tocopherol concentrations at parturition and d 21 postpartum were lower in unsupplemented than in supplemented animals. On d 53 postpartum, no differences in plasma alpha-tocopherol concentrations were found between long-term supplemented and unsupplemented cows. Supplementing vitamin E during the dry period increased alpha-tocopherol content of colostrum.

Relationships among vitamin E, selenium, and bovine blood neutrophils

Effects of vitamin E and selenium supplementation on in vitro phagocytosis and intracellular kill of bacteria by bovine neutrophils were investigated. Diets were not supplemented with vitamin E and selenium during the dry period and first 21 d of lactation. Cows were then assigned to one of four treatment diets for 30 d. Treatment diets were either unsupplemented or supplemented with vitamin E, selenium, or both vitamin E and selenium, in a 2 x 2 factorial arrangement. Peripheral blood neutrophils were isolated from each cow on lactation d 51. Vitamin E supplementation of diets increased intracellular kill of Staphylococcus aureus and Escherichia coli by neutrophils. Intracellular kill of S. aureus was greater in neutrophils isolated from selenium supplemented cows than in neutrophils from cows without supplemental selenium. Intracellular kill of E. coli did not differ between neutrophils from selenium supplemented and selenium unsupplemented cows. Ability of neutrophils to phagocytize either S. aureus or E. coli was independent of vitamin E and selenium.

Bacterial counts associated with recycled newspaper bedding

Bacterial counts associated with recycled newspaper, wood shavings, and pelleted corn cobs used as bedding for lactating dairy cows were compared. Chopped newspaper and pelleted corn cobs had similar gram-negative bacterial, coliform, and streptococcal bedding counts. Staphylococcal counts in pelleted corn cobs were greater than in chopped newspaper. Conversely, gram-negative bacterial, coliform, and staphylococcal counts in chopped newspaper were greater than in wood shavings. Coliform and streptococcal counts did not differ between chopped newspaper and wood shavings bedding materials. Teat swab counts from cows bedded on pelleted corn cobs were greater than those from cows bedded on chopped newspaper for gram-negative bacterial, coliform, Klebsiella species, and staphylococci. Streptococcal teat swab counts did not differ between cows bedded on chopped newspaper and pelleted corn cobs. Cows bedded on chopped newspaper and wood shavings had similar gram-negative bacterial, coliform, and Klebsiella species teat swab counts. Streptococcal and staphylococcal teat swab counts were greater from cows bedded on chopped newspaper than those from cows bedded on wood shavings. Teat swab and bedding counts were correlated. In general, bacterial counts in bedding suggest no advantage in using chopped newspaper over pelleted corn cobs or wood shavings in reducing exposure of teats to environmental mastitis pathogens.

Intramammary challenge of the bovine mammary gland with coliform bacteria during early involution

Isolates of Escherichia coli (n = 12), Klebsiella pneumoniae (n = 20), and Klebsiella oxytoca (n = 10) were used to challenge involuting mammary glands at 7 d of the dry period. Bacteria were selected for challenge on the basis of their ability to grow in a pooled source of dry cow secretion obtained at 21 d of involution. Challenge bacteria were classified as highly adapted (in vitro growth greater than 7 cfu log10/ml) or poorly adapted (growth less than 2 cfu log10/ml) for growth in dry cow secretion. Intramammary infusion of Escherichia coli, K. pneumoniae, and K. oxytoca resulted in 0, 40, and 30%, respectively, of quarters infected. Isolates highly adapted for growth in dry cow secretion caused 75% of K. pneumoniae and 67% of K. oxytoca experimental intramammary infections. Results indicated that the ability to overcome inhibitory properties of dry cow secretion was related to the establishment of K. pneumoniae and K. oxytoca intramammary infections in the dry gland. There was no evidence that growth of E. coli in dry cow secretion related to pathogenicity in the dry gland. Experimental challenge using multiple isolates did confirm the resistance of the involuting mammary gland to E. coli infection.

Relationships among selenium, vitamin E, and mammary gland health in commercial dairy herds

Nine well-managed dairy herds were monitored for 1 yr to determine if bulk tank SCC and rate of clinical mastitis were associated with dietary and plasma Se and vitamin E status. Intakes of Se and vitamin E were 1 to 16 mg/d and 100 to 900 mg/d, respectively. Plasma Se concentrations were correlated positively with intakes of Se below 5 mg/d but were independent of Se intakes above 5 mg/d. Feeding vitamin E increased plasma concentrations of tocopherol, but the influence of dietary vitamin E on plasma concentrations was four times greater for dry cows than for lactating cows probably due to secretion of tocopherol into colostrum and milk. Bulk tank SCC averaged 5.4 log10/ml and decreased significantly as Se concentration in plasma increased. Plasma glutathione peroxidase was correlated positively to Se intake but negatively to SCC. Rate of clinical mastitis was negatively related to plasma Se concentration and concentration of vitamin E in the diet. An apparent interaction between dietary Se and vitamin E was evident since herds fed high amounts of Se tended to have high rates of clinical mastitis, but not if high amounts of vitamin E were fed. These data confirm earlier findings that Se and vitamin E status of dairy cows are related to mammary gland health.

Growth of gram-negative bacteria in dry cow secretion

Gram-negative bacteria (n = 192) isolated from infected bovine mammary glands were tested for growth in a pooled source of dry cow secretion. Growth of Klebsiella pneumoniae in dry cow secretion was greater than growth of Escherichia coli and Klebsiella oxytoca. Escherichia coli originating during the early dry period exhibited greater growth in dry cow secretion than those originating around calving or during lactation. Klebsiella pneumoniae growth did not differ with time of origin of intramammary infection. Escherichia coli, K. oxytoca, and K. pneumoniae growth in a synthetic medium was reduced by apolactoferrin plus Ig. Growth reduction was greatest for E. coli. Citrate reversed growth inhibition. The inhibitory properties of dry cow secretion for E. coli may contribute to the low number of naturally occurring intramammary infections originating during the early part of the dry period. Inhibitory properties of dry cow secretion are partially explained by lactoferrin acting in conjunction with antibody to prevent iron acquisition by many gram-negative bacteria.

Collaborative Study to Determine Effects of Milk Composition on Somatic Cell Counts

Quarter, composite, and bulk tank milk samples were analyzed in a three laboratory collaborative study to determine the relationship of milk fat and protein content with milk somatic cell counts. Milk somatic cell counts were determined by two Coulter counters, a Fossomatic counter, and by direct microscopic somatic cell counting. In general, variability among somatic cell counts measured by different procedures was not related to protein or fat content of milk. The greatest percentage of variation between counts that could be explained by fat content of milk was 20.2% between a Coulter and direct microscopic somatic cell counts. The greatest percentage of variation between counts that could be explained by protein content of samples was 12.9% between a Coulter and Fossomatic counts. Breed of cow from which samples were collected also had little influence on differences among milk somatic cell counts. Differences among milk somatic cell counts due to counting methods did vary among quarter, composite, and bulk tank milk samples.

Serum susceptibility of coliforms isolated from bovine intramammary infections

A total of 35 coliforms isolated from bovine intramammary infections were tested for serum susceptibility. Growth responses of Klebsiella pneumoniae isolated from intramammary infections originating during the dry period were inhibited more than were growth responses of Klebsiella pneumoniae isolated from infections originating during lactation. Escherichia coli growth responses did not differ between isolates originating from dry period and lactational intramammary infections. Mean growth responses to serum did not differ between Klebsiella pneumoniae and Escherichia coli. Bactericidal properties of serum were due to complement activity. The classical pathway of complement appeared to be the principal source of bactericidal activity of serum toward Klebsiella pneumoniae. Alternative and classical pathways of complement were both important for bactericidal effects of serum on Escherichia coli. Iron saturation of serum did not affect growth responses of either Klebsiella pneumoniae or Escherichia coli. These data illustrate that coliforms isolated from intramammary infection originating during the dry period were not more resistant to the bactericidal activity of bovine serum than were coliforms isolated from intramammary infection occurring during lactation.

Field survey of clinical mastitis in low somatic cell count herds

Nine commercial dairy herds, each with low herd milk somatic cell counts, were monitored for 1 yr to determine prevalence of intramammary infections and rates of clinical mastitis. Staphylococcus species was the bacterial group most frequently isolated from quarters at calving and at drying off. Environmental streptococci and coliform intramammary infections totaled less than 6% of quarters at both calving and at drying off. Staphylococcus aureus were isolated from less than 1% of quarters and Streptococcus agalactiae from 0% of quarters at both calving and drying off. A total of 646 clinical cases of mastitis were diagnosed in 548 quarters of 406 cows. Mean rate of clinical mastitis among herds was .457 clinical cases/305 cow-days. Rates of clinical mastitis ranged among herds from .273 to .748 clinical cases/305 cow-days. Coliforms and bacteriologically negative and environmental streptococci accounted for 82.3% of clinical cases. Rates of clinical mastitis and severity of clinical signs differed among herds, seasons of the year, parity groups, and stages of lactation. Rates of clinical mastitis were highest during summer, in first lactation cows, and during the first 7 d of lactation.

Prolonged in vitro exposure of Staphylococcus aureus to germicidal teat dips

Eight strains of Staphylococcus aureus were tested to determine if prolonged exposure to commercial teat dips could enhance bacterial tolerance to teat dips in vitro. All strains of S. aureus were serially plated 15 times on chemically defined agar medium containing sublethal concentrations of linear dodecyl benzene sulfonic acid, chlorhexidine, sodium hypochlorite, and iodophor teat dips. Growth responses of S. aureus to chlorhexidine, sodium hypochlorite, and iodophor were not affected by prolonged exposure to these teat dips. Isolates subcultured on agar containing .1% linear dodecyl benzene sulfonic acid teat dip subsequently had a greater mean growth response to .1% solution of the germicide than did controls subcultured on basal medium. Hemolytic patterns, tube coagulase, clumping factor, and protein A reactions of S. aureus were not altered by exposure to any of the teat dips tested. In general, prolonged exposure to commercial teat dips did not alter germicidal susceptibility of S. aureus.

Bacterial counts in bedding materials used on nine commercial dairies

Bacterial counts were monitored for 1 yr in bedding materials used on nine commercial dairies. Organic materials used to bed lactating cows had significantly higher moisture content and gram-negative bacterial, coliform, Klebsiella species, and streptococcal counts than did inorganic materials. Klebsiella species counts were higher in sawdust than in chopped straw. Streptococcal counts were higher in chopped straw than sawdust. Bacterial counts did not differ between sand and crushed limestone. Gram-negative bacterial and coliform counts were higher during summer and fall than in winter and spring months. Streptococcal counts did not differ among seasons of the year. Linear relationships were significant between total rates of clinical mastitis during lactation and both gram-negative bacterial and Klebsiella species counts in lactating cow bedding. These data indicate that bacterial populations differed between both types of bedding and among seasons of the year. Rates of clinical mastitis were related to bacterial counts in bedding.

Bacterial and Somatic Cell Counts in Bulk Tank Milk from Nine Well Managed Herds1

Factors associated with bulk tank milk bacterial and somatic cell counts were investigated for one year on nine well managed dairies. Geometric mean total bacterial count among dairies was 4.4 × 10³ colony cfu/ml. Geometric mean bulk tank milk somatic cell counts among herds was 265 × 10³ml. Bacterial counts in bulk tank milk were correlated with rates of coliform and environmental streptococcal clinical mastitis cases. Rates of total clinical cases were also correlated with bulk tank milk somatic cell counts. Correlations were measured among bulk tank milk bacterial counts and gram-negative bacterial, coliform, Klebsiella species, and streptococcal counts in materials used to bed lactating cows. Total bacterial and staphylococcal bulk tank milk counts increased when synthetic rubber liners were used greater than 800 quarter milkings. Correlations measured indicated that monitoring bulk tank milk may be an effective means of detecting management changes in herds with low bacterial and milk somatic cell counts.

An automated method of separating patient from ventilator work on the lungs

This paper describes a method of determining the amount of work on the lungs done by the patient and the ventilator using various modes of ventilation. The method uses a pneumotachograph to measure air flow, and measures pressure from an esophageal balloon and at the airway. The patient's work is separated from the ventilator work by analysis of the esophageal pressure. When esophageal pressure is below end-expiratory esophageal pressure during inspiration, work is being done by the patient. When esophageal pressure is above end-expiratory level, the ventilator is doing the work. The calculations are done using an IBM PC computer. The studies of normal subjects show that in the assist mode with increased airway resistance, significant work by the subject is required to trigger the ventilator. Two patients are presented when the assist mode resulted in excessive amounts of work and fatal outcomes. Measurement of the mechanical work required of the patient can provide useful information for the control of ventilator therapy.

Sensitivity and specificity of latex agglutination tests used to identify Streptococcus agalactiae and Staphylococcus aureus isolated from bulk tank milk

Comparisons were made among rapid latex agglutination tests and conventional biochemical tests used to identify Streptococcus agalactiae and Staphylococcus aureus. Ninety-eight streptococci and 149 staphylococci isolated from bulk tank milk were tested. Sensitivity and specificity for the latex agglutination test used for identification of Str agalactiae were 97.6 and 98.2%, respectively. Sensitivity and specificity for the latex agglutination test used for identification of S aureus were 90.2 and 67.5%, respectively. Of 25 staphylococci considered false-positive by the latex agglutination test, 14 (56%) were considered tube coagulase-positive. Fifteen staphylococci considered false-positive by latex agglutination test had biotypes representative of S hyicus of S xylosus.

Rate of environmental mastitis in quarters infected with Corynebacterium bovis and Staphylococcus species

Rates of environmental streptococcal and coliform intramammary infections were compared among quarters uninfected and infected with either Corynebacterium bovis or Staphylococcus species. Rate of environmental streptococcal intramammary infections was 3.9 times greater in C. bovis-infected quarters than in uninfected quarters. Rate of environmental streptococcal infections was 2.6 times greater in quarters infected with Staphylococcus species than in uninfected quarters. Rate of coliform intramammary infections did not differ among quarters with differing bacteriological infection statuses. Quarters infected with either C. bovis or Staphylococcus species had higher milk SCC than did uninfected quarters. Intramammary infection with either Corynebacterium bovis or Staphylococcus species did not protect quarters against coliform infection. Rate of environmental streptococcal infections was enhanced in quarters infected with either C. bovis or Staphylococcus species.

Growth responses of environmental mastitis pathogens to long-chain fatty acids

Streptococcus uberis, Streptococcus faecalis, Escherichia coli, and Klebsiella pneumoniae were tested for susceptibility to long-chain fatty acids predominant in teat canal keratin. Antibacterial activity of free fatty acids on each bacterial species was measured after 12 h in synthetic media. Growth responses of all three strains of Streptococcus uberis were completely inhibited by C18:3 and those of two of three strains by C18:2 at 1 micrograms/ml. None of the fatty acids tested were bactericidal to Streptococcus faecalis. Saturated fatty acids C14 and C16 were more bacteriostatic to Streptococcus faecalis than were polyene fatty acids. Growth responses of coliform species were not affected by long-chain fatty acids. In general, environmental mastitis pathogens were resistant to fatty acids predominant in teat canal keratin.

Growth responses of Staphylococcus aureus and Streptococcus agalactiae to Corynebacterium bovis metabolites

Staphylococcus aureus and Streptococcus agalactiae growth responses to metabolites of Corynebacterium bovis cultured in media containing polyoxyethylenesorbitan monolaurate, monooleate, or trioleate and milk were determined. Filter sterilized metabolites of 48-h C. bovis cultures in synthetic media were added to cultures of Staph. aureus and Strep. agalactiae. Staphylococcus aureus and Strep. agalactiae were inoculated into 12-h C. bovis milk cultures. Growth responses of Staph. aureus and Strep. agalactiae were not affected by C. bovis metabolites of synthetic media. Staphylococcus aureus growth was inhibited during logarithmic and stationary phases in milk containing mixed cultures of C. bovis compared with growth in pure Staph. aureus cultures. Streptococcus agalactiae growth curves were similar in pure and C. bovis mixed cultures. Fatty acid compositions were not different in sterile milk and milk containing bacterial cultures. Growth responses of Staph. aureus and Strep. agalactiae were not related to concentration of C. bovis metabolites or fatty acid content of media in which C. bovis were cultured.

Growth inhibition of mastitis pathogens by long-chain fatty acids

Staphylococcus aureus, Staphylococcus hyicus, Streptococcus agalactiae, and Corynebacterium bovis were tested for sensitivity to long-chain fatty acids predominant in teat canal keratin. Antibacterial activity of free fatty acids on each bacterial species was measured after 12 and 24 h in chemically defined media. Polyene C18:2 and C18:3 acids were bactericidal to each species at less than or equal to 10(5) ng/ml-1. The most bacteriostatic saturated fatty acids were C12 and C14. Streptococcus agalactiae growth was inhibited more by fatty acids after 24 h than after 12 h. No incubation time effect on growth responses of other species was determined. Polyoxyethylenesorbitan monooleate had a neutralizing effect on the bactericidal activity of polyene acids on C. bovis. Corynebacterium bovis were unable to grow in synthetic media containing individual free fatty acids as the sole source of preformed fatty acids. A relationship between bacterial species commonly isolated from bovine teat canals with resistance to fatty acids predominant in keratin was not evident.

Effects of teat dipping on intramammary infections by staphylococci other than Staphylococcus aureus

Effects of intramammary infections in herds 1) either not teat dipping or postmilking teat dipping with either 2) linear dodecyl benzene sulfonic acid, 3) chlorhexidine, or 4) iodophor containing products were determined. Duplicate quarter foremilk samples were collected once from all lactating cows in 16 herds, four for each practice. Mean percentage of quarters infected with Staphylococcus species other than Staph. aureus was 11.0 in herds not teat dipping and 7.2 in herds teat dipping. Prevalence of Staphylococcus species intramammary infections in herds teat dipping with linear dodecyl benzene sulfonic acid was comparable to herds not teat dipping and greater than in herds using chlorhexidine and iodophor. The predominant Staphylococcus species in herds not teat dipping was Staph. epidermidis (37.1%). Staphylococcus hyicus constituted 48.5% of total Staphylococcus species intramammary infections in herds teat dipping and 12.4% in herds not teat dipping. Differences were not observed among SCC for quarters infected with different Staphylococcus species. Application of germicidal teat dips appeared to have selectively altered both prevalence and distribution of Staphylococcus species intramammary infections.

Field trial evaluation of premilking teat disinfection

Efficacy of premiliking teat disinfection (predipping) with good udder preparation was compared with good udder preparation alone on four well-managed, commercial dairy farms. Three teat dip formulations containing iodophor were used for predipping. Predipping reduced the rate of intramammary infection with major mastitis pathogens approximately 54%. Infection rate with esculin-positive streptococci and coliforms was reduced more than 51%. Udder infections with coagulase-negative staphylococci were not controlled by predipping.

Survey of Bulk Tank Milk using Blood-Esculin Agar Counts 1

Milk from bulk tanks of 2,931 dairy herds were sampled and evaluated using trypticase blood-esculin agar, somatic cell, standard plate and preliminary incubation counts. Percent samples with trypticase blood-esculin agar counts >1 × 10² colony forming units/ml by organisms were Staphylococcus aureus , 33; Staphylococcus spp., 84; Streptococcus agalactiae , 47; esculin-positive streptococci, 72; coliforms, 73; and other microbes, 89. Trypticase blood-esculin agar counts were useful for identifying primary bacterial contaminants. Correlations were low between trypticase blood-esculin agar counts of specific bacterial groups and somatic cell, standard plate and preliminary incubation counts.

Fatty acid composition of bovine teat canal keratin

Keratin from 507 excised teats was pooled, separated into three samples, and analyzed for fatty acid composition of extracellular and intracellular lipids. Mean weight of keratin collected per teat canal was 8.97 mg. Extracellular lipids were recovered in petroleum ether. Intracellular lipids were extracted in chloroform: methanol (2:1, vol/vol) solution. Average keratin wet weight of extracellular and intracellular lipid fractions were 37.1 and 21.9 mg/g, respectively. Polar and nonpolar lipids were present in both fractions. Predominant fatty acids in extracellular and intracellular lipids were C16, C18:1, and C18. Extracellular lipids contained greater concentrations of C4 to C18:1 fatty acids than did intracellular lipids. Percent of total fatty acid weight comprised by each of C4, C10, C12 and C14 was also significantly greater in extracellular than intracellular fractions. Intracellular lipids contained a greater concentration and percent total fatty acid content comprised by C18:2 than extracellular lipids. Data suggest lipids accessible at the keratin interface are in part of milk fat origin.

Comparison of isotonic and hypertonic fluids in resuscitation from hypovolemic shock

Hypertonic electrolyte solutions provide effective fluids for resuscitation of burn patients and concurrent replacement of hemorrhage. Infusion of mannitol has also been advocated as a means of increasing cardiac output in acutely ill patients. Pigs which were bled to one-third of their blood volume were used in this random study of resuscitation with Ringer's lactate solution (RL), hypertonic saline solution (HSL) and RL with mannitol added (HMR) to give the same osmolality as HSL. Smaller volumes of the hyposmolar solution than of RL restored blood pressure and cardiac output. RL and HSL restored and maintained cardiac output more effectively than HMR. At 24 hours, HSL maintained blood pressure most effectively.

Comparison of four test procedures to identify Staphylococcus aureus isolated from bovine intramammary infections

A comparison was made between conventional tube coagulase, macrocupsular coagulase, latex agglutination, and miniaturized biochemical test systems for identification of Staphylococcus aureus of bovine origin. A total of 303 gram-positive, catalase-positive cocci of bovine origin were tested. Agreement between each pair of 4-hour tube coagulase, macrocupsular coagulase, latex agglutination, and miniaturized biochemical test results within isolates was greater than 95.0. Seventeen (5.6%) isolates were test negative for 4-hour tube coagulase, but test positive for 24-hour tube coagulase. Thirteen (76.5%) of these isolates were identified as S hyicus, 3 were S aureus, and 1 was not identified.

Effects of Corynebacterium bovis infection on susceptibility to major mastitis pathogens

Experimental challenge procedures were used to study infectivity and virulence of Corynebacterium bovis. Challenge procedures using Staphylococcus aureus (Newbould 305) and Streptococcus agalactiae (McDonald 44) were used to study effects of Corynebacterium bovis infections on superinfection with major pathogens. Rate of infection under experimental challenge conditions was significantly greater with Corynebacterium bovis than previously observed for Staphylococcus aureus or Streptococcus agalactiae. Principal location of Corynebacterium bovis colonization appeared to the teat canal region, although the organism was isolated from 75% of the teat cisterns by puncture technique. Quarters with Corynebacterium bovis infections were more resistant to infection by Staphylococcus aureus than bacteriologically negative quarters. Quarters infected with Corynebacterium bacterium bovis were approximately 8.5-fold more susceptible to Streptococcus agalactiae infection than negative quarters. Somatic cell counts were doubled in negative quarters that developed Corynebacterium bovis infections; the geometric mean was 2.4 X 10(5).

A personal computer system for testing gas exchange, heart, lungs, ventilatory pump

This paper reports the development of a computer system for testing gas exchange and lung function in the ICU. The essence of the system is a software package that uses an IBM personal computer for data processing and analysis. Front end hardware is modular, as is software, so that portions or all of the system can be used. The system provides measurements of lung mechanics work, functional residual volume, spirometry, oxygen uptake, carbon dioxide output, lung water, blood gas interpretation, hemodynamics. Reports are provided by standard data base manager and so are easily customized.