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Biomedical subjects

D L Brooks

Publications and source records attributed to D L Brooks.

At least 19 recordsLinked to original sources
PubMed1995

Experimental oral inoculations in birds to evaluate potential definitive hosts of Neospora caninum.

Experimental oral inoculations to evaluate potential definitive hosts of Neospora caninum were conducted by feeding infected rodent tissues to 9 carnivorous birds of 4 species. Birds included 2 red-tailed hawks (Buteo jamaicensis), 2 turkey vultures (Cathartes aura), 2 barn owls (Tyto alba), and 3 American crows (Corvus brachyrhynchus). The rodents (mice or rats) had been inoculated with 100,000 culture-derived tachyzoites of N. caninum 1-6 mo before feeding to the birds. Fecal samples were collected from each bird daily for 1 mo after feeding rodents and examined for oocysts by fecal flotation. In addition, processed aliquots from all avian fecal samples were fed to BALB/c mice. Five weeks after feeding, mice were bled and sera were tested for antibodies against N. caninum. One to two months later, mice were killed and brain tissue was examined microscopically for protozoal cysts. While occasional oocysts were found in avian fecal samples, these were likely not N. caninum because they were not infective to BALB/c mice. It was concluded that the bird species tested are not likely to be definitive hosts of N. caninum.

Animals↗
PubMed1991

Characteristics of an unusual mycoplasma isolated from a case of caprine mastitis and arthritis with possible systemic manifestations.

A mycoplasma designated strain GM790A was isolated from milk and internal organs of 2 lactating goats showing mastitis and arthritis. The isolate was not related serologically to any of the currently known ovine-caprine mycoplasmas, except an isolate designated Mycoplasma sp. G, first recorded from the external ear canal of clinically normal goats in Australia. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis and restriction enzyme DNA studies of strain GM790A and Mycoplasma sp. G revealed similar but not identical patterns. The inoculation of strain GM790A into the teat canal of 2 lactating goats resulted in an abrupt diminution of lactation leading to mastitis and agalactia in about 3 days. A maximum of 1 x 10(7) colony-forming units (CFU) of the mycoplasma were shed per ml of mammary secretion. Milk production partially resumed at a low level 3 weeks postinoculation, the longest period tested, but the milk still contained 1 x 10(2) CFU of the agent. The results of this study indicate that strain GM790A possesses pathogenic potential for the goat and most probably represents a new species of the genus Mycoplasma.

Animals↗
PubMed1991

Pharmacokinetic properties of enrofloxacin in rabbits.

The pharmacokinetic properties of the fluoroquinolone antimicrobial enrofloxacin were studied in New Zealand White rabbits. Four rabbits were each given enrofloxacin as a single 5 mg/kg of body weight dosage by IV, SC, and oral routes over 4 weeks. Serum antimicrobial concentrations were determined for 24 hours after dosing. Compartmental modeling of the IV administration indicated that a 2-compartment open model best described the disposition of enrofloxacin in rabbits. Serum enrofloxacin concentrations after SC and oral dosing were best described by a 1- and 2-compartment model, respectively. Overall elimination half-lives for IV, SC, and oral routes of administration were 2.5, 1.71, and 2.41 hours, respectively. The half-life of absorption for oral dosing was 26 times the half-life of absorption after SC dosing (7.73 hours vs 0.3 hour). The observed time to maximal serum concentration was 0.9 hour after SC dosing and 2.3 hours after oral administration. The observed serum concentrations at these times were 2.07 and 0.452 micrograms/ml, respectively. Mean residence times were 1.55 hours for IV injections, 1.46 hours for SC dosing, and 8.46 hours for oral administration. Enrofloxacin was widely distributed in the rabbit as suggested by the volume of distribution value of 2.12 L/kg calculated from the IV study. The volume of distribution at steady-state was estimated at 0.93 L/kg. Compared with IV administration, bioavailability was 77% after SC dosing and 61% for gastrointestinal absorption. Estimates of predicted average steady-state serum concentrations were 0.359, 0.254, and 0.226 micrograms/ml for IV, SC, and oral administration, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1991

Efficacy of enrofloxacin in the treatment of respiratory pasteurellosis in rabbits.

Fourteen New Zealand White rabbits with respiratory signs of naturally occurring Pasteurella multocida infections were treated with either an injectable or water-soluble oral formulation of enrofloxacin. Antimicrobial efficacy was evaluated by scoring clinical signs in the rabbits and recovery of the organisms. Seven (87%) of eight rabbits treated with the injectable regimen (5 mg/kg every 12 hours for 14 days) became culture-negative with no clinical signs within 72 hours after initiation of treatment. Six rabbits treated with the oral formulation (200 mg/liter of drinking water for 14 days) also became culture-negative and had no clinical signs 3 to 7 days after treatment began, but P. multocida was recovered from several sites in three (50%) rabbits. No rabbits showed any signs of gastroenteric disturbances.

Administration, Oral↗
PubMed1991

Response of adult New Zealand white rabbits to enrichment objects and paired housing.

Enhancing the psychological well-being of laboratory animals has received much attention recently. Although many studies have been undertaken to determine the effects of cage enrichment techniques on dogs and nonhuman primates, other than scant empirical observations, little has been done to measure these events objectively in lagomorphs. We studied adult female New Zealand White (NZW) rabbits to learn if, when given the opportunity, individual rabbits would use different enrichment objects placed in their cages, and to determine if rabbits preferred to be in proximity to one another, or apart. Three different objects were evaluated with eight rabbits individually housed in conventional cages. Each object introduced into individual rabbit cages stimulated substantial interaction, especially chewing behavior. Eight other rabbits were pair-housed in a modified caging system with a special access port between two separate cages. When given a choice, rabbits preferred to be in the same cage with other rabbits. In both studies, individual behaviors were monitored, as well as either the type of interaction and percentage of observations spent with each object or, in the housing study, percentage of observations involved with different types of activity, and relative location of the paired rabbits.

Animal Husbandry↗
PubMed1990

Use of ivermectin for treatment of ear mite infestation in rabbits.

Ivermectin was used to treat ear mite infestation in 480 rabbits in 2 commercial rabbitries. Ivermectin (cattle formulation) injected sc at a dosage of 400 to 440 micrograms/kg of body weight repeated in 18 days appeared to be safe and effective in reducing the prevalence of ear mites in naturally infested rabbits.

Animals↗
PubMed1990

Eradication of ear mites from naturally infested conventional research rabbits using ivermectin.

Rabbits naturally infested with ear mites were treated with ivermectin injection for cattle, subcutaneously at the rate of 400 mcg/kg; which was repeated in 15 to 17 days. Rabbits treated as described and housed in a conventional vivarium environment were found to be free of mites during a subsequent 33 to 139 day observation period. Side effects were minimal and associated with occasional transient discomfort at the injection site. Ivermectin appears to be safe and effective for treating rabbits with ear mites. The prospects of eradicating mites from infested rabbit colonies using this method of treatment is promising.

Animals↗
PubMed1988

Ampicillin, tetracycline, and chloramphenicol resistant Haemophilus influenzae in adults with chronic lung disease. Relationship of resistance to prior antimicrobial therapy.

Antibiotic resistance in 1,003 sputum isolates of Haemophilus influenzae from adults with chronic lung disease was assessed from January 1983 through June 1986. The incidence of resistance was 3.2% for tetracycline, 0.6% for chloramphenicol, and 12.5% for ampicillin. Resistance to ampicillin or tetracycline usually occurred alone, while 100% of chloramphenicol resistant isolates were co-resistant to tetracycline or ampicillin. More than 90% of antibiotic resistant isolates were nontypable and belonged to biotypes II, III, or V. Chart reviews of 331 patients revealed that patients with ampicillin resistant isolates were more likely than control subjects to have received ampicillin in the prior 6 wk (33% versus 6%, p less than 0.0001), whereas patients with isolates resistant to tetracycline or chloramphenicol plus tetracycline were more likely to have received tetracycline than control subjects (24% and 50%, respectively, versus 5%, p less than 0.005). The incidence of ampicillin resistance and the reluctance of physicians caring for adults to use chloramphenicol suggests that a newer cephalosporin such as cefotaxime may be the initial therapy of choice for severe H. influenzae disease in our patient population.

Adult↗
PubMed1987

Caprine mycoplasmosis: an outbreak of mastitis and arthritis requiring the destruction of 700 goats.

An acute outbreak of mastitis and arthritis in a herd of 700 goats required the destruction of all but the few animals that were held for observation. The milk of nearly all of about 400 lactating does contained almost pure cultures of Mycoplasma putrefaciens with counts in 150 samples up to 1 X 10(9) colony forming units/ml. At post mortem examination the joints of both the adults and kids contained a fibrinopurulent discharge. M putrefaciens was isolated in pure cultures and large numbers from joints, tissues and fluid not previously known to harbour this mycoplasma: brain, kidneys, lungs, lymph nodes, uterus and urine. The outbreak was milkborne and initiated by infusion of the pathogen into the teat canal by poor hygiene in the milking parlour and by feeding raw colostrum to kids. All but 12 of the herd of 700 goats were killed or sold for slaughter.

Abortion, Veterinary↗
PubMed1987

Comparison of caprine mycoplasmosis caused by Mycoplasma capricolum, Mycoplasma mycoides subsp. mycoides, and Mycoplasma putrefaciens.

We reviewed the disease process in goats caused by Mycoplasma capricolum, M. mycoides subsp. mycoides, and M. putrefaciens and compared mycoplasma-infected goats (particularly young kids) for microanatomic changes. M. capricolum and M. mycoides subsp. mycoides cause a nearly identical disease: septicemia leading to pyrexia, high morbidity and mortality, interstitial pneumonia, arthritis (including polyarthritis), and mastitis. Until recently, M. putrefaciens was known only as a cause of mastitis. However, a new isolate of M. putrefaciens may be transiently septicemic, as evidenced by polyarthritis with isolations from joints, lung, brain, kidney, pleural fluid, uterus, and urine.

Animals↗
PubMed1987

Tylosin concentrations in rat serum and lung tissue after administration in drinking water.

Tylosin has low in vitro minimum inhibitory concentrations against Mycoplasma pulmonis but levels attainable in rat serum or lung tissue have not been reported previously. Tylosin levels in rat serum and lung tissue were determined after administration of tylosin in the drinking water. Rats were given water mixed with a commercially available preparation of tylosin base, vitamins, and dextrose. Although the calculated amount of tylosin added to the water was intended to provide a concentration of 500 mg/L, the concentration attained was 70-79 mg/L and decreased rapidly with time. Bioassay of serum and lung tissue after 1-10 days of continuous medication revealed no detectable tylosin concentrations (less than 0.1 microgram/ml) in serum, while lung tissue from all treated rats contained tylosin (means = 10.69 +/- 2.66 micrograms/gm tissue, range = 3.93 to 18.14, n = 59). These concentrations are over ten times the reported in vitro minimum inhibitory concentrations against M. pulmonis which indicates that tylosin administration in drinking water may be useful in the treatment of M. pulmonis pneumonia in rats.

Animals↗
PubMed1986

Induction of mycoplasmosis in goat kids by oral inoculation with Mycoplasma mycoides subspecies mycoides.

A one-time, orally administered dose of greater than or equal to 1 X 10(6) colony-forming units of Mycoplasma mycoides subspecies mycoides was sufficient to induce clinical mycoplasmosis (n = 37) terminating in fatal mycoplasmemia in 73% (37 of 51) of the clinically affected kids. The pathogen was isolated from the blood samples as early as 24 hours after oral inoculation; hot, swollen joints frequently were evident by 4 or 5 days after exposure. Pyrexia (to 42.3 C) was detected in about 95% (35 of 37) clinically affected kids, although about 5% (2 of 35) died peracutely without fever or other premonitory signs. At necropsy, the cardinal lesions were a fibrinopurulent polyarthritis and red, patchy to diffuse areas of consolidation in 1 or more lung lobes. At death, usually within 4 to 16 days after oral inoculation, the concentration of M mycoides subspecies mycoides in the blood was 1 X 10(6) to 1 X 10(7) colony-forming units/ml. Histologically, the kids had diffuse fluid leakage into pulmonary alveoli and to a lesser extent into small vessels of various other organs. Fibrinocellular thrombi of terminal occurrence were occasionally present in various organs. The meningeal, pleural, and peritoneal surfaces had vascular leakage and a minimal perivascular accumulation of leukocytes. The disease was contagious. Of 14 noninoculated control kids in close confinement with affected kids, 8 (57%) developed mycoplasmosis in 7 to 15 days and died of mycoplasmemia. The remaining 5 noninoculated kids remained healthy, as did noninoculated kids that were kept isolated from affected kids.

Administration, Oral↗
PubMed1986

Q fever vaccination of sheep: challenge of immunity in ewes.

Adult ewes (17 months of age) were vaccinated against Coxiella burnetii, using a formalin-inactivated whole cell (WC) phase I Henzerling strain vaccine or a chloroform methanol residue (CMR) vaccine. Nineteen pregnant ewes were placed in 3 categories [(i) unvaccinated, (ii) WC vaccine, and (iii) CMR vaccine] and were challenge exposed at approximately the 100th day of gestation with 210,000 plaque-forming units of C burnetii inoculated subcutaneously. Shedding of rickettsiae was measurably reduced, but was not prevented in vaccinated groups, as shown by inoculating ewes' placental tissues, amniotic fluid, and colostrum into mice, as well as by histopathologic lesions of placental tissues. The rickettsiae were shed in the placenta, amniotic fluid, or colostrum in 6 nonvaccinated ewes. In comparison, rickettsiae were detected in placental inoculations from 2 of 6 ewes in the WC vaccine group and 1 of 6 in the CMR group. In contrast to those in the vaccinated ewes, placentitis, high concentrations of rickettsiae in microscopic preparations, and weak lambs were typical for the nonvaccinated ewes.

Animals↗
PubMed1985

Amoxicillin-clavulanic acid in the treatment of lower respiratory tract infections caused by beta-lactamase-positive Haemophilus influenzae and Branhamella catarrhalis.

Twenty-one adult patients hospitalized with lower respiratory tract infections due to Branhamella catarrhalis or Haemophilus influenzae or both were treated with the combination of oral amoxicillin and potassium clavulanate (Augmentin) in an open, noncomparative clinical trial. Diseases included pneumonia, empyema, and exacerbations of bronchiectasis and chronic lung disease. Thirteen of 16 B. catarrhalis and six of nine H. influenzae isolates were beta-lactamase positive. The patients with B. catarrhalis were treated for a mean of 5.3 days, and those with H. influenzae were treated for a mean of 7.0 days. The overall response to therapy was excellent, with 18 of 19 beta-lactamase-producing strains eradicated on therapy. One patient secondarily infected with Pseudomonas aeruginosa was a clinical failure, and two patients with H. influenzae who became culture positive again after therapy were considered microbiologic failures. Gastrointestinal side effects (especially nausea) were common, although all patients completed a course of therapy. Sputum levels of amoxicillin were surprisingly low (less than 0.05 to 0.54 micrograms/ml), a finding which may explain the high relapse rate (22%) seen with H. influenzae, as these are below the usual MICs of amoxicillin for this organism. The combination of amoxicillin plus potassium clavulanate appears to be an excellent drug for treatment of beta-lactamase-producing strains of these two species, although mild gastrointestinal side effects are common.

Aged↗
PubMed1985

Relationship of upper and lower urinary tract infection and bacterial invasion of uroepithelium to antibody-coated bacteria test results in female dogs.

Urinary tract infection was demonstrated in 12 female dogs via bacteriologic culture of a specimen of bladder urine collected by antepubic cystocentesis. Escherichia coli was isolated in pure culture from the urine of 9 dogs. Urine specimens from 2 dogs contained E coli and alpha-streptococci and from 1 dog contained Streptococcus zymogenes in pure culture. In 6 dogs, urinary tract infection was limited to the urinary bladder, whereas 6 dogs had unilateral or bilateral culture-positive renal pelvic urine as well (specimens collected by percutaneous nephropyelostomy). An antibody-coated bacteria (ACB) test was conducted on a portion of the bladder urine specimen from each dog, and the urinary tissues from these 12 dogs and from 6 healthy, noninfected female dogs were examined at necropsy. Tissues were given a subjective score based on the severity of the lesions seen microscopically. Histologic scores, bacterial cultural results, and ACB test results were examined for significance. A significant difference was found in the histologic scores between infected and noninfected dogs (P less than 0.025), but comparisons among histologic scores, cultural results, and ACB test results were not significant among infected dogs. The ACB test could neither be used to localize bacterial infection within the urinary tract nor could it be used to indicate the presence of bacterial invasion of the uroepithelium in dogs.

Animals↗
PubMed1984

Pathogenicity of Mycoplasma capricolum and Mycoplasma putrefaciens.

Mycoplasma capricolum causes high morbidity and mortality in goats. Young kids fed a one-time oral dose of greater than or equal to 1 X 10(5) colony-forming units of the GM13 isolate usually died during the septicemic phase. The cardinal lesions were a fibrinopurulent polyarthritis and an acute, diffuse interstitial pneumonia. Lactating goats exposed to low numbers of the organism via the teat canal experienced similar lesions and acute mastitis, agalactia, and hardened udders. The intramammary inoculation of M. putrefaciens caused only mastitis; infection could not be initiated by oral, intranasal, or i.m. exposure.

Animals↗