The Effect of Two Different Oxytetracycline Treatments in Experimental Ehrlichia phagocytophilaInfected Lambs

Abstract

The effect of 2 different oxytetracycline treatments in acute E. phagocytophila infected lambs was investigated. Twenty 5-month-old lambs of the Dala and Rygja breeds were used. Ten lambs were inoculated intravenously with a stabilate of an ovine E. phagocytophila strain. On the third day of fever, 4 lambs were given long-acting oxytetracycline (Terramycin prolongatum vet®, Pfizer) (20 mg/kg) intramuscularly and another 4 lambs were given short-acting oxytetracycline (Terramycin vet®, Pfizer) (10 mg/kg) intravenously for 5 consecutive days. The lambs were examined for the presence of Ehrlichia infection by blood smear evaluation, polymerase chain reaction (PCR) and antibody titre against E. equi. One month after the last antibiotic treatment, 250 ml citrate blood from each of these lambs were inoculated into each of 10 susceptible lambs, which were observed during the following 6 weeks. The results indicate that oxytetracycline given in the acute stage of the infection may effectively teminate the development of fever, rickettsemia and weight reduction in E. phagocytophila infected lambs. No difference was observed between the 2 treatment groups. However, at least 3 of 8 antibiotic treated lambs (37.5%) were still infected with granulocytic Ehrlichia 3 months after treatment.

Integrated transcriptomic and proteomic analysis of the global response of Wolbachia to doxycycline-induced stress

“…For instance, a 2- to 5-day course of doxycycline is still effective for the treatment of spotted fever group rickettsiae ( Botelho-Nevers et al , 2012 ), and although isolates of the scrub typhus agent O. tsutsugamushi with reduced doxycycline susceptibility were reported from northern Thailand in the mid-1990s ( Watt et al , 1996 ) this drug has remained effective in other endemic areas ( Rajapakse et al , 2011 ). However, despite this apparent lack of heritable resistance, many members of the Rickettsiales can persist following tetracycline treatment and may recrudesce months or even years after the cessation of therapy ( Andrew and Norval, 1989 ; Stuen and Bergstrom, 2001 ; McClure et al , 2010 ). This is also the case for Wolbachia , as a 2-week course of oxytetracycline only depleted the bacteria transiently from O. ochengi worms, with full recovery of both the endosymbionts and their host 6 months later ( Gilbert et al , 2005 ).…”