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1.
The efficacy of 3 antibiotic formulations was measured in the treatment of artificially induced anaplasmosis in the early stages of an ascending parasitemia (1% to 4%) in 23 splenectomized calves. Group 1, consisting of 5 calves, served as nontreated controls. Four calves (group 2) were treated 1 time with 10 mg of oxytetracycline (T-50)/kg of body weight IM; 5 calves (group 3) were treated 3 times with 10 mg of T-50/kg IM; 5 calves (group 4) were treated 1 time with 20 mg of an experimental oxytetracycline (T-200)/kg IM; and 4 calves (group 5) were treated 1 time with 10 mg of a synthetically derived antibacterial agent, doxycycline (D-100)/kg IM. All control calves died and 1 of 4 calves died that was treated 1 time with T-50. Other deaths did not occur. All treatments were effective in moderating the infective process, but T-50 given 3 times and T-200 given 1 time were markedly more effective than T-50 and D-100 given 1 time. There appeared to be little or no difference in therapeutic efficacy between T-50 and D-100 given 1 time and between T-50 given 3 times and T-200 given 1 time.  相似文献   

2.
Migration of bovine macrophages under agarose was used to assess cellular immunity in 7 nonvaccinated calves and 9 calves vaccinated with Salmonella typhimurium. The 9 vaccinated calves were allotted to 4 groups. Group I calves were vaccinated twice orally with small doses of virulent S typhimurium; group II calves were vaccinated twice orally with genetically altered aromatic-dependent (aro-) S typhimurium SL3261; group III calves were vaccinated twice IM with small doses of virulent S typhimurium; and group IV calves were vaccinated twice IM with aro- S typhimurium SL1479. Samples of blood were obtained from these calves at 2 weeks after the 2nd vaccinal dose was given, and lymphocytes were harvested, using lymphocyte separation medium. Lymphocytes in serum-free medium were then incubated with S typhimurim antigen for 48 hours. Lymphocytes were then transferred to antigen-free medium and incubated for 48 hours, and the supernatant was assayed for the migration-inhibition factor (MIF). Lymphocyte supernatant was assayed for MIF by incubating it for 48 hours with 2.0 X 10(4) alveolar macrophages in agar wells. The macrophage migration distance was measured and compared with control values. Macrophage migration was inhibited in the presence of supernatant of lymphocytes from vaccinated calves that had been incubated with antigen, indicating the presence of the MIF in the supernatant. Migration distances, as a percentage of control, were 33% for group I calves (oral vaccination, virulent vaccinal organism), 60% for group II calves (oral vaccination, aro- vaccinal organism), 41% for group III (IM vaccination, virulent organism), and 25% for group IV (IM vaccination, aro- vaccinal organism).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

3.
Ceftriaxone was administered to Israeli-Friesian male calves by IV and IM routes. The antibiotic was administered IV (10 mg/kg) to 10 calves and IM to 23 calves; 8 were given the antibiotic at the rate of 10 mg/kg of body weight, 5 were given 20 mg/kg, and 10 were given 10 mg/kg, together with probenecid at 40 mg/kg. Serum concentration vs time profiles measured after IV and IM administration were analyzed by use of statistical moment theory. The following mean values +/- SD were found: elimination half-life (t1/2) was 83.8 +/- 8.6 minutes after IV administration and significantly longer 116.8 +/- 20.5 minutes (P less than 0.001) after IM administration at 10 mg/kg. The t1/2 was increased to 141.3 +/- 24.4 minutes by the coadministration of probenecid and to 145.0 +/- 48.2 minutes by doubling the IM dosage to 20 mg/kg. The total body clearance was 3.39 +/- 0.42 ml/min/kg and the renal clearance 2.37 +/- 0.74 ml/min/kg. The specific volume of distribution was 0.2990 +/- 0.0510 L/kg. The average mean residence time (MRT) was 94.0 +/- 12.3 minutes after IV administration and 137.6 +/- 19.9 minutes after IM administration of ceftriaxone at 10 mg/kg. The MRT was increased to 198 +/- 48.8 minutes by the coadministration of probenecid and to 191.0 +/- 59.4 minutes by doubling the IM dose. The former value was significantly different from the MRT after IM administration of the antibiotic at 10 mg/kg. Bioavailability of ceftriaxone after IM administration at 10 mg/kg and at 20 mg/kg was 78% and 83%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

4.
In a study to evaluate the effect of flunixin meglumine on secretory diarrhea, 11 calves were assigned to 3 groups: group 1 (n = 3) served as controls, group-2 calves (n = 4) were given 2.2 mg of flunixin meglumine/kg, IM at 7 AM and 3 PM, and group-3 calves (n = 4) were given 2.2 mg of flunixin meglumine/kg, IM at 7 AM, 11 AM, and 3 PM. All calves were given approximately 200 micrograms of heat-stable Escherichia coli enterotoxin (STa) orally at 8 AM. Mean cumulative fecal output for groups 1, 2, and 3 was 1,331.0 +/- 317.2 g, 1,544.3 +/- 154.4 g, and 785.5 +/- 276.5 g, respectively. There was a significant (P less than 0.05) reduction in mean fecal output in group-3 calves, compared with that in groups 1 and 2. Calves in group 2 tended to have a delay, but not a reduction, in their fecal output. At 12 hours, hemoconcentration was significantly (P less than 0.05) greater in group-1 calves than in group-2 or group-3 calves.  相似文献   

5.
Transmission of bovine leukosis virus by blood inoculation   总被引：3，自引：0，他引：3  
The experimental transmission of bovine leukosis virus (BLV)-infected whole blood was studied in 2 groups of Holstein calves. The 1st group of 4 BLV-seronegative calves was given 10 microliters of whole blood by either the IM, IV, subcutaneous, or intradermal routes. All 4 calves seroconverted to BLV within 8 weeks after they were inoculated. The 2nd group, also comprising 4 calves, was given the equivalent of 1 microliter of whole blood by the described routes. These calves seroconverted to BLV by 14 weeks after they were inoculated. The results indicated that small volumes of whole blood administered by 4 different routes were effective in the spread of BLV.  相似文献   

6.
A subcutaneous soft tissue infection model in calves was used to study the in vivo response of Pasteurella haemolytica to erythromycin and dexamethasone. Two tissue chambers were implanted SC in each of 12 calves. At 45 days after implantation, all tissue chambers were inoculated with an erythromycin-sensitive strain of P haemolytica. Starting 24 hours after inoculation, calves were allotted to 4 groups of equal size and a 2 x 2-factorial arrangement of treatments was applied: 3 calves were given erythromycin (30 mg/kg of body weight, IM, for 5 days), 3 calves were given dexamethasone (0.05 mg/kg, IM, for 2 days), 3 calves were given erythromycin and dexamethasone, and the remaining calves served as nontreated controls. Chamber fluids were tested daily, and the response to treatment was measured. Neither erythromycin nor dexamethasone affected viability or growth of bacteria within tissue chambers. Dexamethasone had no effect on the influx of neutrophils into infected chambers. Despite repeated administration of a high dose of erythromycin and attainment of adequate concentration in serum, erythromycin concentration in chamber fluids did not exceed the minimal inhibitory concentration established in vitro. These results indicate that the clinical efficacy of erythromycin against P haemolytica sequestered in consolidated pneumonic lesions may not be well correlated with predictions based on serum pharmacokinetic and in vitro susceptibility data.  相似文献   

7.
OBJECTIVE: To determine the efficacy of florfenicol for treatment of calves with naturally occurring infectious bovine keratoconjunctivitis (IBK). DESIGN: Randomized controlled field trial. ANIMALS: 63 beef calves and 80 dairy calves between 4 and 12 months of age. PROCEDURE: Calves were randomly assigned to 1 of 3 treatment groups. Calves in the SC treatment group received a single dose of florfenicol (40 mg/kg [18.2 mg/lb of body weight), SC, on day 0. Calves in the IM treatment group received florfenicol (20 mg/kg [9.1 mg/lb]), IM, on days 0 and 2. Calves in the control group received injections of saline solution (0.9% NaCl), IM, on days 0 and 2. Calves were reevaluated every other day for 20 days after treatment. RESULTS: Corneal ulcers healed by day 20 in 48 of 49 (98%) calves treated with florfenicol IM, 39 of 42 (93%) calves treated with florfenicol SC, and 33 of 52 (63%) control calves. CONCLUSIONS AND CLINICAL RELEVANCE: Florfenicol administered SC (1 dose) or IM (2 doses 48 hours apart) was effective for treatment of calves with naturally occurring IBK.  相似文献   

8.
The effect of parenteral penicillin treatment on the intestinal microbiota was determined by monitoring the phenotypic antimicrobial resistance among Escherichia coli in 19 calves (15 calves received treatment and four calves were healthy controls) and by examining changes in the fecal microbial community structure using molecular fingerprinting techniques in a subset of eight calves (five treated calves and three control calves). After five days of penicillin treatment an increased resistance to multiple unrelated antimicrobial agents, including non-β-lactams, was seen in E. coli from treated calves, and this was not seen in the controls. Automated ribosomal intergenic spacer analysis (ARISA) and terminal restriction fragment length polymorphism (TRFLP) revealed that penicillin treatment causes a significant variation in the microbial structure within an individual calf. The study shows that parenteral administration of penicillin has an impact on the composition of the fecal microbiota in calves, and on the antimicrobial resistance pattern of their fecal E. coli.  相似文献   

9.
Ten Holstein calves were divided into 2 groups. Five calves served as nonvaccinated controls, and 5 calves were vaccinated IM at 2 and 3 weeks of age with 10(9) aromatic-dependent (aro-) Salmonella typhimurium strain SL1479 containing O antigens 1, 4, 12. Serious adverse reactions to vaccination were not observed in the calves. Mean maximum rectal temperature increase in the vaccinated calves was 1.5 C. One calf had diarrhea and depressed appetite for 1 day after vaccination. At 5 weeks of age, all calves were challenge exposed orally with 1.5 X 10(11) virulent S dublin strain SL1367 (O antigens 9,12). After challenge-exposure inoculum was given, 1 of 5 vaccinated calves died and 4 of the 5 nonvaccinated calves died (P less than 0.05). Thus, some cross serotype protection against S dublin was induced by parenteral vaccination of calves with aro- S typhimurium strain SL1479, although protection was not complete.  相似文献   

10.
Calves with diarrhea often have small intestinal overgrowth with Escherichia coli bacteria, regardless of the inciting cause for the diarrhea, and 30% of systemically ill calves with diarrhea have bacteremia, predominantly because of E coli. Antimicrobial treatment of diarrheic calves should therefore be focused against E coli in the small intestine and blood, the 2 sites of infection. Fecal bacterial culture and antimicrobial susceptibility testing is not recommended in calves with diarrhea because fecal bacterial populations do not accurately reflect small intestinal or blood bacterial populations and because the break points for susceptibility test results have not been validated. Antimicrobial efficacy is therefore best evaluated by the clinical response of a number of calves to treatment, with calves randomly assigned to treatment groups. Amoxicillin, chlortetracycline, neomycin, oxytetracycline, streptomycin, sulfachloropyridazine, sulfamethazine, and tetracycline administered PO are currently labeled in the United States for the treatment of calf diarrhea. On the basis of published evidence for the oral administration of these antimicrobial agents, only amoxicillin can be recommended for the treatment of diarrhea. Dosage recommendations are amoxicillin trihydrate (10 mg/kg PO q12h) or amoxicillin trihydrate-clavulanate potassium (12.5 mg combined drug/kg PO q12h) for at least 3 days; the latter constitutes extra-label drug use. Parenteral administration of broad-spectrum beta-lactam antimicrobials--ceftiofur (2.2 mg/kg IM or SC q12h) and amoxicillin or ampicillin (10 mg/kg IM q12h)--or potentiated sulfonamides (25 mg/kg IV or IM q24h) is recommended for treating calves with diarrhea and systemic illness; both constitute extra-label drug use. In calves with diarrhea and no systemic illness (normal appetite for milk, no fever), it is recommended that the health of the calf be monitored and that oral or parenteral antimicrobials not be administered.  相似文献   

11.
Sixteen 7-week-old Holstein male calves were inoculated with sporulated oocysts of Eimeria zuernii. Four calves (controls) were euthanatized and necropsied at 14 and 20 days after inoculation (DAI). Two calves were treated with 20 mg of dexamethasone (IM) on 13, 14, and 15 DAI and euthanatized and necropsied 17 DAI and 2 calves were given similar treatments and necropsied 20 DAI. The 8 other calves were euthanatized and necropsied 20 DAI. Two were started on the anticoccidial drug decoquinate in feed 13 DAI; 2 others were given decoquinate on the same schedule plus dexamethasone on 13,14, and 15 DAI. Two calves were given the antibiotic narasin in feed beginning 13 DAI and 2 calves were given parasin on the same schedule plus dexamethasone on 13,14, and 15 DAI. All calves, except 2 controls necropsied 14 DAI and 4 calves given decoquinate, discharged moderate-to-large numbers of oocysts in feces and had moderate-to-serve changes in fecal consistency. Histologic examinations revealed large numbers of endogenous stages in tissues of calves treated or not treated with dexamethasone. Few endogenous stages were observed in tissues from calves that were given decoquinate or decoquinate plus dexamethasone. Calves given narasin or narasin plus dexamethasone had moderate-to-large numbers of endogenous stages in the tissues.  相似文献   

12.
The effects of pneumonia on the pharmacokinetics of erythromycin administered IM and the tissue concentration changes with time were evaluated in 2-month-old calves. Pneumonia was induced by injection of Pasteurella haemolytica cultures through the thoracic wall into each lung. Six days prior to induction of pneumonia, erythromycin (15 mg/kg) was administered in a single IM dose. Erythromycin was administered again 48, 72, and 96 hours after injection of P haemolytica. On the third day of erythromycin administration (96 hours), the calves were serially euthanatized in groups of 4 calves each at 2, 5, 8, 12, 18, and 24 hours after the final dose was given. Tissue concentrations of erythromycin in kidney, liver, lung, muscle, CSF, and serum were determined. Neither the serum concentrations nor the overall pharmacokinetic values were significantly (P less than or equal to 0.05) changed by pneumonia. The concentrations of erythromycin were maximal at 5 hours for liver, muscle, and serum and at 8 hours for CSF, kidney, and lung. Serum and muscle concentrations were similar, whereas concentrations in CSF were lower than in serum and higher in kidney, liver, and lung. The lung/serum ratios were approximately 2.5 to 3 at 8 through 24 hours after IM administration. The peak concentration in lung was approximately 6 micrograms/g at 8 hours.  相似文献   

13.
Cell extracts that were prepared from blood mononuclear leukocytes from 66 samples obtained from 6 clinically normal calves contained mean 2',5'-oligoadenylate (2',5'-oligo[A]) synthetase activity sufficient to synthesize 186 +/- 82 pmol of 2',5'-oligo(A)/h/10(6) cells. Calves had no measurable serum interferon (IFN) activity. Five calves were given IM injections of 10(4), 10(5), 5 x 10(5), 10(6), and 10(7) U of bovine IFN-alpha 1/kg of body weight at 2-week intervals. Five dosing sequences were used with a 5 x 5 Latin square design so that each calf received each dose once. Activity of 2',5'-oligo(A) synthetase increased at 24 hours in response to all dosages of IFN and then declined following first-order kinetics, with an apparent half-life (t1/2) of 2.1 +/- 0.5 days. The area under the concentration-time curve for 2',5'-oligo(A) synthetase increased with dose of IFN more rapidly than did peak response. Serum IFN that was measured at 1-day intervals following administration of IFN was consistently measurable only at dosages above 10(6) U of IFN/kg. The t1/2 for circulating IFN was 12.4 +/- 1.0 hours. Over all dosages, increases in 2',5'-oligo(A) synthetase activity were measurable for 3.5 days longer than were increases in IFN following IM injection of IFN. None of the calves developed detectable anti-IFN antibodies.  相似文献   

14.
A virulent Salmonella dublin isolate was made histidine-requiring (his-) to allow recognition. The his- derivative, SL1367 (still calf-virulent), was then given by transduction and mutation, a transposon-generated non-reverting aromatic biosynthesis (aro) defect; this defect caused loss of virulence for the mouse. The his- aro- derivative strain, SL1438, was effective as a live vaccine in mice. Twenty male Holstein calves were divided into 4 groups. Groups I, II, and III were vaccinated IM at 2 weeks and at 3 weeks of age with aromatic-dependent (aro-) S dublin strain SL1438. Groups I and III received freshly prepared vaccine and group II received lyophilized vaccine. Serious adverse reactions to the vaccination were not seen. After vaccination, the mean maximum increase in rectal temperature was 1.8 C in group I and III calves and 0.6 C in group II calves. Fewer group II calves developed diarrhea (1 of 5) or positive blood cultures (0 of 5) after vaccination compared with group I and III calves (6 of 10 and 5 of 10, respectively). Postvaccination diarrhea was mild and of short duration. Group IV was comprised of 5 nonvaccinated calves. At 5 weeks of age, all calves were challenge exposed orally. Group I, II, and IV calves were challenge exposed with 10(11) virulent S dublin SL1367. Group III was challenge exposed with 10(11) virulent S typhimurium UCD 108-11. Subsequently, fever and diarrhea (lasting 1 to 3 days), but no deaths, were observed in the vaccinated calves. Four of the 5 nonvaccinated (group IV) calves died (P less than 0.001) within 8 days after challenge exposure. Aro- S dublin SL 1438 did not cause serious adverse effects and provided protection against oral challenge exposure with either virulent S dublin or S typhimurium.  相似文献   

15.
The data on antimicrobials in bob veal calves obtained by USDA-Food Safety Inspection Service (FSIS) during the fiscal year 1988 were reviewed. Of 3,095 calf antibiotic and sulfonamide test (CAST)-positive carcass submissions, 967 were chosen by FSIS for antimicrobial residue analyses. Specimens of muscle, liver, and kidney were obtained at abattoirs as a part of the FSIS program, and the results were reviewed by calf submission. At least 1 tissue from each of 425 submissions contained neomycin. Unidentified microbial inhibitors were found in 291 submissions. Streptomycin was found in 86 carcass submissions, penicillin in 81, sulfamethazine in 73, tetracycline HCl in 59, and gentamicin in 53. Other monitored agents were found in less than 50 submissions each. Only 257 submissions included evaluation for sulfonamides, but sulfamethazine was found in 28.4% of them. Chloramphenicol was not detected. Concentrations of neomycin in kidney specimens ranged from 0.25 to greater than 100 ppm, and differed among the 3 regional laboratories (West, Midwest, and East). The western region had the greatest proportion of low-concentration specimens, whereas the midwestern laboratory had the largest proportion of specimens with very high concentrations (greater than or equal to 100 ppm) of neomycin in kidney tissue. Data to identify the sources and causes of the residues were not available. However, the western laboratory evaluated CAST-positive submissions from calves certified to be antimicrobial-free, whereas the other laboratories evaluated submissions from certified and noncertified calves; therefore, this may partially explain regional patterns for neomycin quantities in kidney specimens. Neomycin predominated among CAST-positive verifications. A high prevalence of unidentified microbial inhibitors suggests further identification may be warranted.  相似文献   

16.
Recurrent infection in calves vaccinated with infectious bovine rhinotracheitis-(IBR) modified live virus was induced by dexamethasone (DM) treatment given 49 days after challenge exposure with virulent IBR virus. Nonchallenge-exposed IM and intranasally vaccinated calves did not excrete the virus after DM treatment; however, IM and intranasally vaccinated and subsequently challenge-exposed calves excreted the challenge-exposure virus into the nasal secretions 5 to 11 days and 6 to 10 days after the DM treatment, respectively. The calves were killed 15 to 18 days (experiment 1) and 14 days (experiment 2) and DM treatment was started and then were examined by histopathologic and fluorescent antibody techniques. All DM-treated calves that were inoculated with the vaccinal virus and challenge exposed with the virulent virus developed nonsuppurative trigeminal ganglionitis and encephalitis. On the contrary, the DM-treated nonchallenge-exposed vaccinated calves did not have lesions in the peripheral nervous system and CNS. Infectious bovine rhinotracheitis virus antigens were not observed in tissues of any of the calves examined (experiments 1 and 2) by fluorescent antibody techniques. These observations indicated that the modified live IBR virus neither produced lesions nor induced latent infection and that modified live IBR virus vaccination did not protect the calves against the establishment of a latent infection after their exposure to large doses of the virulent IBR virus.  相似文献   

17.
Plasma disposition, protein binding, urinary recovery, and renal clearance of sulfamethazine (SMZ), its N4-acetylsulfamethazine (N4-SMZ), and its 2 hydroxy metabolites--6-hydroxymethylsulfamethazine (SCH2OH) and 5-hydroxysulfamethazine (SOL)--and the glucuronide of the latter were studied in 7 cows and 7 calves to determine the relationship between these values and the age of the animal and dosage applied. A capacity-limited hydroxylation of SMZ into SCH2OH was observed in cows and calves given dosages of 100 to 200 mg/kg. A biphasic SMZ elimination curve and steady state in SCH2OH plasma concentration (6 to 15 micrograms/ml) were observed. The N4-SMZ plasma concentration-time curve was parallel to that of SMZ at the dosages and in all animals. The total body clearance and the cumulative urinary recovery (expressed as percentage of the dose) for SMZ and its metabolites depended on drug dosage and age of the animals. At dosages of SMZ less than 25 mg/kg, the main metabolite in the urine of calves and cows was SCH2OH (23% to 55.2%), whereas in calves given a larger dosage (100 mg/kg), the N4-SMZ and SOH percentages increased. The plasma protein binding of SMZ and its metabolites depended on the SMZ plasma concentration. Hydroxylation lowered the protein binding (from 75-80%) to 50%. The renal clearance of SMZ was dependent on urine flow in all animals. The renal clearance of the SCH2OH metabolite was 2 to 3 times greater than the creatinine clearance value; thus, this compound was excreted by glomerular filtration and partly by tubular secretion.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

18.
Aseptic and septic inflammatory diseases often are associated with marked changes in tissue and sera trace element kinetics. Iron and zinc sequestration by the host may serve as a protective effect against microbial proliferation, but may deprive host tissues of these necessary elements as well. Conversely, systemic iron administration has been shown to increase susceptibility to, and severity of, infectious diseases, although deficient iron stores may be repleted. Escherichia coli enteritis in calves provides a model wherein the effects of enteric iron antagonism and parenteral iron supplementation may be studied simultaneously. Male calves (n = 12) were given (IM injection) 300 mg of iron-dextran after base-line blood samples were obtained, then the calves were allotted to 4 groups (each of 3 calves): group 1 (control)--orally given nonpathogenic E coli; group 2--orally given enterotoxigenic B44 E coli; group 3--orally given deferoxamine (50 mg/kg, twice a day); group 4--orally given gallium (4 mg/kg; twice a day). Calves were studied for 8 days; blood samples were obtained each day (day 1 through day 8) for hematologic and serum biochemical analyses. There were significant increases in serum iron concentration and % saturation in all calves within 24 hours of iron-dextran administration, which returned to base-line values in all but group 4 (given gallium) within 3 days. In the exceptional group (4), total iron-binding capacity decreased with time, as in the other groups, but serum iron concentration remained significantly increased, implying gallium interference with systemic iron assimilation.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

19.
Ten female beef calves weighing approximately 180 kg each were allotted to 2 groups of 5 each before they were given (orally) monensin (50 mg/kg of body weight). In group A, the calves were given (IM) a commercial selenium-vitamin E (Se-E) preparation (0.25 mg of Se and 17 IU of alpha-tocopherol/kg of body weight) at 72 and 24 hours before monensin was given. The calves in group B were injected at the 2 times with isotonic saline solution. Clinical signs of monensin toxicosis, including lethargy and recumbency, appeared on day 2 in the calves given the Se-E pretreatment, compared with the onset on day 1 in the saline solution-pretreated calves. All calves in the 2 groups died, but mean survival time was longer in group A (4.4 vs 2.2 days). Lesions of monensin toxicosis were myocardial necrosis, skeletal myonecrosis, pulmonary congestion, and rumenitis. The frequency and severity of the lesions were similar for both groups of calves. The results of the present study indicate that Se-E pretreatment modifies the development of monensin toxicosis in cattle.  相似文献   

20.
This study in six cows compared serum concentrations of trimethoprim and sulphadoxine (16 mg/kg body weight (BW)) after once daily and twice daily administration, and of procaine penicillin G (20,000 IU/kg BW) after subcutaneous (SQ) and intramuscular (IM) administration, and evaluated postmortem tissue concentrations of penicillin following SQ treatment. Trimethoprim and penicillin were measured microbiologically, and sulphadoxine colorimetrically. Using minimum inhibitory concentrations (MIC), trimethoprim reached serum concentrations above 0.5 μg/mL from 15 minutes to 120 minutes, and sulphadoxine exceeded 9.5 μg/mL from 10 minutes to 12 hours, after administration. At 24 hours after treatment, both had declined to below the MIC of most organisms. A second treatment at 12 hours maintained concentrations of sulphadoxine above 9.5 μg/mL for a further 24 hours. For penicillin administered IM and SQ, concentrations that peaked at 0.88 μg/mL would inhibit most common grampositive bacteria for the entire 24 hour period and fastidious gram-negative organisms from 90 minutes to 12 hours after SQ treatment, but for virtually the entire period after IM administration. Mean ± SD concentrations (μg/mL) of penicillin at euthanasia, five days after the last SQ administration, were 1.15 ± 1.27 (injection site), 1.00 ± 0.80 (liver), 0.90 ± 0.58 (renal cortex), 0,58 ± 0.17 (renal medulla), 0.13 ± 0.11 (diaphragm), 0.10 ± 0.08 (gluteal muscle), and 0.06 ± 0.04 (fat). Therefore, except for the most sensitive organisms, twice daily injection of trimethoprim/sulphadoxine (16 mg/kg BW) may be required. Penicillin G administered SQ at 20,000 IU/kg BW should provide effective serum levels for as long as IM administration against gram-positive organisms, but for only about half as long against gram-negative bacteria. The label withdrawal time of five days cannot be used when penicillin is given SQ at 20,000 IU/kg BW for three days.  相似文献   

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