Experimental evaluation of tulathromycin as a treatment for Campylobacter jejuni abortion in pregnant ewes

Abstract

OBJECTIVE To evaluate the efficacy of tulathromycin for prevention of abortion in pregnant ewes when administered within 24 hours after experimental inoculation with Campylobacter jejuni. ANIMALS 20 pregnant ewes between 72 and 92 days of gestation. PROCEDURES All ewes were inoculated with a field strain of C jejuni (8.5 × 108 to 10.6 × 108 CFUs, IV). Eighteen hours later, ewes received either tulathromycin (1.1 mL/45 kg [2.4 mg/kg], SC; n = 10) or sterile saline (0.9% NaCl) solution (1.1 mL/45 kg, SC; sham; 10). Ewes were euthanized immediately after observation of vaginal bleeding, abortion, or completion of a 21-day observation period. Necropsy was performed on all ewes, and tissue specimens were obtained for bacterial culture and histologic examination. RESULTS 1 sham-treated ewe and 1 tulathromycin-treated ewe developed signs of severe endotoxemia and were euthanized within 24 hours after C jejuni inoculation. Seven sham-treated and 2 tulathromycin-treated ewes developed vaginal bleeding or aborted and were euthanized between 4 and 21 days after C jejuni inoculation. The proportion of tulathromycin-treated ewes that developed vaginal bleeding or aborted during the 21 days after C jejuni inoculation (2/9) was significantly less than that for the sham-treated ewes (7/9). CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that administration of tulathromycin to pregnant ewes following exposure to C jejuni was effective in decreasing the number of C jejuni–induced abortions. Because of concerns regarding the development of macrolide resistance among Campylobacter strains, prophylactic use of tulathromycin in sheep is not recommended.

New and alternative strategies for the prevention, control, and treatment of antibiotic-resistant Campylobacter

“…33 Tetracycline is frequently used for control of the disease, and more recently tulathromycin has become an alternative treatment due to the concern with tetracycline resistance in Campylobacter. 34 Infectious infertility, aka bovine genital campylobacteriosis, characterized by infertility, early embryonic deaths and to a lesser extent abortion, is caused by C. fetus subsp. venerealis (CFV) and is an economically important disease of cattle worldwide.…”

Pharmacokinetics of tulathromycin in pregnant ewes (Ovis aries) challenged with Campylobacter jejuni

“…Ewes were administered 1.5 ml of 50 mg/ml flunixin meglumine (Prevail) IV to lessen the impact of endotoxin. This was followed by 1-1.25 ml of 8.5X10 8 CFU/ml C. jejuni IA3902 IV [12]. A small amount of blood was aspirated back into the syringe and reinfused following inoculation to assure that all of the inoculum was administered into the jugular vein.…”

“…Pharmacokinetic studies in pregnant ewes have demonstrated that tulathromycin reaches detectable levels in fetal plasma and amniotic fluid that persist for days following administration to the ewe [11]. The potential clinical effectiveness of tulathromycin in C. jejuni exposed pregnant ewes has been confirmed in a study utilizing an IV C. jejuni challenge model in which tulathromycin treatment resulted in a statistically significant (p < .05) decrease in the rate of vaginal bleeding/abortion in pregnant ewes compared to untreated controls [12].…”

“…Field and experimental studies of campylobacter abortion in sheep have consistently identify large numbers of the organism in the maternal uterus, fetal placenta and lung, and to a lesser extent fetal liver [12]. It is currently unknown how tulathromycin accumulates in these tissues in ewes undergoing infection with C. jejuni.…”

The pathology of natural and experimentally induced Campylobacter jejuni abortion in sheep

“…8,18 This enhanced understanding of placental vasculature, combined with the availability of well-preserved tissues from multiple, experimentally induced C. jejuni abortions archived in our laboratory, has the potential to aid in better defining the specific locations of bacterial colonies within affected placentas. 26,27 Abortion diagnostic testing traditionally focuses on the aborted fetus and placenta. Although these tissues routinely yield a diagnosis, they fail to provide insight into corresponding changes within the female reproductive tract, which may be undervalued in terms of their relative importance in the pathogenesis of Campylobacter abortion.…”