Increasing effect of a high dose of PG-1 peptide on the infectivity of Chlamydophila abortus.

Cathelicidins are antimicrobial peptides, stored by mammalian leukocytes, showing an antimicrobial activity against bacteria, fungi, protozoa and enveloped viruses. In accordance with other authors, we reported in a previous study that the protegrin-1 (PG-1), at 80 microg mL(-1), inhibited the in vitro growth of Chlamydia trachomatis serovars D, H and L2; however, we observed an increased infectivity of some animal chlamydial species after their treatment with the same PG-1 concentration. In this study, the treatment of LLC-MK2 cells with PG-1 before chlamydial infection resulted in an increased infectivity of Chlamydophila abortus probably due to their easier entry into the host cells, whereas no increase in S26/3 infectivity was detected in LLC-MK2 cells treated with PG-1 postchlamydial infection.

Pharmacokinetics of enrofloxacin and its efficacy in comparison with doxycycline in the treatment of Chlamydophila felis infection in cats with conjunctivitis.

The concentrations of enrofloxacin were measured in the tears, saliva and serum of 14 cats with signs of upper respiratory tract infection and eight with no signs, after daily doses of 5 mg/kg. Enrofloxacin concentrations above the minimum inhibitory concentration of Chlamydophila felis were found in the saliva and tears of the cats with and without signs of upper respiratory tract infection. In a prospective randomised clinical trial, the efficacy of enrofloxacin against C. felis infection in cats with conjunctivitis was compared with the efficacy of doxycycline. Twenty-five cats were randomly assigned to treatment with either enrofloxacin or doxycycline for 14 days; 15 of the cats tested positive for C. felis by an immunofluorescent antibody test on conjunctival swabs. The two treatment groups showed equal improvements in the clinical signs of conjunctivitis and C. felis infection status; in each group three cats were still C. felis antigen-positive after the 14-day course of treatment, indicating a persistent infection. No side effects were observed in the cats treated with enrofloxacin.

Use of quantitative real-time PCR to monitor the response of Chlamydophila felis infection to doxycycline treatment.

Fifteen cats infected with Chlamydophila felis were monitored for the presence of C. felis DNA on ocular swabs by using real-time PCR and for clinical signs of disease. The cats were assigned to three groups: oral doxycycline at 10 mg/kg of body weight/day for 7 days (six cats), oral doxycycline at 10 mg/kg/day for 14 days (five cats), and an untreated control group (four cats). The untreated cats remained positive for C. felis throughout the trial; clinical signs were most severe on days 14 to 21 postinfection, and then they declined. Treatment with 7 and 14 days of doxycycline decreased C. felis relative copy numbers and clinical signs rapidly. C. felis became undetectable in some of the cats during or after treatment. However, after the cessation of treatment, a recurrence of high relative copy numbers of C. felis and severe clinical signs in all cats was seen. Rescue treatment with 21 days of doxycycline was successful at eliminating infection in eight of the cats; a further 28 days of doxycycline was required to eliminate infection in the remaining three cats. It was concluded that 7, 14, and, in some cases, 21 days of treatment with oral doxycycline will not eliminate C. felis infection. At least 28 days of treatment with doxycycline is required to ensure elimination of the organism. Real-time PCR is a sensitive technique for monitoring C. felis infection and the response to antibiotic treatment.

Genetic and pharmacological inhibition of poly(ADP-ribose) polymerase-1 interferes in the chlamydial life cycle.

Chlamydiaceae are intracellular bacteria responsible for a variety of infections, ranging from asymptomatic to very severe, in humans and animals. We have investigated the role of poly(ADP-ribose) polymerase-1 (PARP-1) in Chlamydophila abortus infection using PARP-1-/- and their littermates PARP-1+/+ mice. Infection was resolved more efficiently by PARP-1-/- than PARP-1+/+ mice. However, the inflammatory response was similar in both strains, suggesting a potential role for PARP-1 in the cross-talk between this microorganism and the host cells. PARP-1-/- fibroblasts showed a 10-fold lower rate of chlamydiae production than PARP-1+/+. Moreover, a strong inhibition of bacterial production was also observed after pharmacological inhibition of PARP-1 activity in McCoy cells. Likewise, PARP-1 inhibition induced a higher level of cell death of infected cells, interfering in this way with the normal bacterial cell cycle. Overall, we identify PARP-1 as a new molecule involved in chlamydial developmental cycle, although the intrinsic mechanisms deserve further studies.

Inclusion counter: a public domain image analysis system for measurement of Chlamydiaceae growth in vitro.

The traditional method of measuring chlamydial growth in vitro, counting Chlamydiaceae inclusions by eye, is time-consuming and error prone. This paper describes a novel automated image analysis system suitable for high-throughput screening of novel anti-Chlamydiaceae compounds. The software, Inclusion Counter v3.0, is freely available in the public domain (http://www.image-analysis.co.uk).

Gamma interferon fails to induce expression of indoleamine 2,3-dioxygenase and does not control the growth of Chlamydophila abortus in BeWo trophoblast cells.

The BeWo trophoblast cell line does not constitutively express the tryptophan degrading enzyme indolamine 2,3-dioxygenase (IDO), nor can IDO expression be induced by gamma interferon. This correlates with the inability of BeWo cells to control the growth of Chlamydophila abortus, in contrast to effects observed in HeLa cells treated with gamma interferon.