Administration of ticarcillin in combination with clavulanic acid intravenously and intrauterinely to clinically normal oestrous mares

Minimum inhibitory concentrations of selected antimicrobials against Escherichia coli and Trueperella pyogenes of bovine uterine origin

Minimum inhibitory concentrations (MIC) of 9 antimicrobials for isolates of 2 common bovine intrauterine bacterial pathogens, Escherichia coli (n=209) and Trueperella pyogenes (n=35), were determined using broth microdilution methodology. The isolates were recovered from dairy cows from 7 herds postpartum using the cytobrush technique. The pathogens were initially identified using phenotypic techniques. Additionally, PCR was used to confirm the identity of T. pyogenes isolates and to categorize the E. coli isolates into phylogenetic groups A, B1, B2, and D. Minimum inhibitory concentrations in excess of published cut-points or bimodal distributions of MIC indicated potential antimicrobial resistance to ampicillin, cefuroxime, cephapirin, and oxytetracycline for E. coli, and to oxytetracycline for T. pyogenes. Of the antimicrobials tested, ticarcillin/clavulanic acid, ceftiofur, and enrofloxacin had the lowest MIC for these 2 pathogens. Differences in MIC of some antimicrobials were found between herds, age, breeds, and E. coli phylogenetic groups. Isolation of E. coli with an MIC ≥8μg/mL of oxytetracycline at 23d postpartum was associated with a lower probability of pregnancy within 6wk of commencement of breeding compared with those isolates with an MIC <8μg/mL (relative risk=0.66). Minimum inhibitory concentrations for uterine pathogens were determined for isolates from New Zealand dairy cows. However, in the absence of either epidemiological or clinical interpretive criteria, the interpretation of these MIC remains unclear. Further studies are required to define interpretative criteria, including determination of pharmacokinetic and pharmacodynamic profiles for antimicrobials.

In vitro elution of amikacin and ticarcillin from a resorbable, self-setting, fiber reinforced calcium phosphate cement

OBJECTIVE

To determine in vitro elution characteristics of amikacin and ticarcillin from fiber reinforced calcium phosphate beads (FRCP).

SAMPLE POPULATION

Experimental.

METHODS

FRCP beads with water (A), amikacin (B), ticarcillin/clavulanate (C), or both amikacin and ticarcillin/clavulanate (D) were bathed in mL phosphate-buffered saline (PBS) at 37°C, 5% CO(2) and 95% room air. PBS was sampled (eluent) and beads were placed in fresh PBS at time points 1 and 8 hours and 1, 2, 3, 4, 5, 6, 7, 10, 12, 14, 18, 21, 25, 28, 35, 42, 49, and 56 days. Antibiotic concentration and antimicrobial activity of eluent against Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae were determined.

RESULTS

Both antibiotics eluted in a bimodal pattern. Beads with a single antibiotic eluted 20.8 ± 2.5% of amikacin and 29.5 ± 0.8% of ticarcillin over 56 days. Coelution of the antibiotics resulted in a lower proportion (AUC(0-∞) ) of antibiotics eluted for both amikacin (9.5 ± 0.2%) and ticarcillin (21.7 ± 0.09%). Bioassay of antimicrobial activity of the eluent (t = 1, 8, and 24 hours) established reduced antimicrobial activity of amikacin from combination beads (D).

CONCLUSIONS

FRCP beads with amikacin or ticarcillin/clavulanate, but not the combination, are suitable carriers for wound implantation.

CLINICAL RELEVANCE

Duration before complete resorption of FRCP beads in vivo should be determined before clinical use as a resorbable depot. The results of this study underscore the importance of testing drug combinations, despite success of the combination systemically, before their use in local applications.

Ceftiofur derivates in serum and endometrial tissue after intramuscular administration in healthy mares

Endometritis is one of the major problems in the horse breeding industry. The use of antibiotics for treatment of endometritis in the mare is recommended as best practice. The intrauterine application of antibiotics, however, has been under discussion over the last years because of concerns about its efficacy. The systemic use of antibiotics has been considered more effective because of its better distribution within the uterus. The objective of the present study was to determine the concentration of ceftiofur derivates in serum and endometrial tissue after intramuscular administration. Specifically, the authors tested the hypothesis that ceftiofur concentrations in serum and endometrial tissue remain above the minimum inhibitory concentration (MIC) for common uterine pathogens for 24 h. Nine mares in estrus received a single dose of 2.2 mg/kg ceftiofur hydrochloride intramuscular per kg of body weight. Blood samples and endometrial tissue were obtained immediately before treatment (-1 h) and 2 h and 24 h after treatment. Endometrial tissue was collected with a Kevorkian biopsy punch. Additional blood samples were collected 4 h and 10 h after treatment from the jugular veins. For determination of ceftiofur derivates in serum and endometrial tissue a high performance liquid chromatography (HPLC) assay was used. Results in serum and uterine tissue revealed greatest concentration of ceftiofur at 2 h and lowest concentrations at 24 h after treatment. Concentrations of ceftiofur at 2 and 24 h after treatment were significantly greater in serum than in endometrial tissue, but remained above the reported MIC for Streptococcus equi zooepidemicus and Escherichia coli in both serum and endometrial tissue until 24 h after treatment.

Pharmacokinetics of ticarcillin in the loggerhead sea turtle (Caretta caretta) after single intravenous and intramuscular injections

Three captive loggerhead sea turtles, Caretta caretta, were used in four trials, one i.v. and three i.m., to determine the pharmacokinetic properties of a single dose of ticarcillin. For the i.v. study, each turtle received a single 50 mg/kg dose and blood samples were collected at 0, 0.5, 1, 2, 4, 6, 8, and 12 hr and at 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, and 14 days after administration. For the i.m. study, each turtle received one of three dosages (25, 50, or 100 mg/kg) in a randomized complete block design and blood samples were collected at the same time intervals. Each trial was separated by a minimum of 28 days to allow for complete drug clearance. Drug concentration in plasma was determined by a validated liquid chromatography-mass spectrometry assay. For the i.v. study, the elimination half-life was 5.0 hr. The apparent volume of distribution and plasma clearance were 0.17 L/kg and 0.0218 L/hr/kg, respectively. For the i.m. study, mean time to maximum plasma concentrations ranged from 1.7 ( +/- 0.58) hr in the 50 mg/kg group to 3.7 (+/- 2.5) hr in the 100 mg/kg group. Mean bioavailability ranged from 45% ( +/- 15%) in the 50 mg/kg group to 58% (+/- 12%) in the 100 mg/kg group, and the mean residence time ranged from 7.5 ( +/- 2.6) hr in the 25 mg/kg group to 16 (+/- 6.8) hr in the 100 mg/kg group. Two turtles had slight alanine aminotransferase elevations that were not clinically apparent at two different dosages, but otherwise, blood chemistries were unaffected. Possible i.m. dosage regimens for loggerhead sea turtles are 50 mg/kg q24 hr or 100 mg/kg q48 hr. Liver enzymes should be monitored during treatment.

Reproductive Tract Infections in Horses

Diagnosis, treatment, and, ultimately, prevention of reproductive disease are vital components of equine veterinary medicine. A thorough understanding of anatomy and physiology is necessary to reconcile the pathologic findings of disease. Only then can a rational treatment plan be formulated. Many recent advances in knowledge about the reproductive system of multiple species have application to the mare and stallion.

Endometrial tissue concentrations of enrofloxacin after intrauterine administration to mares

Endometritis in mares is a common cause of infertility. Conventional treatments of the disease have mostly been unsuccessful, so new therapeutic alternatives need to be investigated. This study evaluated the uterine disposition and plasma pharmacokinetic behaviour of a commercial formulation of enrofloxacin (EFX) given by the intrauterine (i.u.) route (2.5 mg/kg) in healthy mares. In order to evaluate the uterine inflammatory response, an initial histopathological study assessing polymorphonuclear cell infiltration was carried out in 20 mares over a 14-day period after treatment. In a second study, 6 healthy adult mares were used for the pharmacokinetic study. Samples of uterine tissue and plasma were collected from 0 to 24 h after the i.u. treatment with 5% EFX solution. Samples were analysed by conventional microbiological assay using an EFX-sensitive strain of Escherichia coli (ATCC 25922). There was a moderate but statistically nonsignificant inflammatory response following i.u. administration of either the formulation or the vehicle alone. Pharmacokinetic analysis of the uterine concentrations of EFX showed a slow and sustained depletion, with EFX remaining at concentrations above the MIC for 24 h after treatment. The area under the concentration-time curve obtained for the uterus suggested that EFX and its metabolites are specifically retained in the uterus, which is the target tissue for bacterial colonization. Neither study provided any evidence of EFX toxicity. In conclusion, these results are encouraging and suggest that EFX may be a useful local treatment in mares with bacterial endometritis.