Conjunctivitis Caused by a SwineChlamydia Trachomatis-Like Organism in Gnotobiotic Pigs

Abstract

Abstract. The objective of this study was to determine whether a chlamydial strain recovered from growing and finishing swine with conjunctivitis or keratoconjunctivitis could cause the same infections in gnotobiotic pigs. The strain shares biological characteristics with Chlamydia trachomatis. After propagation in Vero cells and preparation of the inoculum (10 7 inclusion-forming units/ml), chlamydial strain H7 was instilled into the ventral conjunctival sac (0.15 ml/sac) of 12 anesthetized 3-day-old gnotobiotic piglets. Four age-matched gnotobiotic piglets were anesthetized and sham infected with uninfected cell culture lysates. None of the principal piglets developed clinical symptoms of conjunctivitis or keratoconjunctivitis. Principal piglets necropsied 7 days postinfection (DPI) had histologic lesions of mild or moderate conjunctivitis; immunohistochemical evaluation revealed chlamydial antigen in conjunctival epithelium. A majority of principal piglets necropsied at 14-28 DPI had histologic lesions of mild conjunctivitis, but chlamydial antigen was not detected by immunohistochemistry. The results indicated that chlamydial strain H7 can cause mild or occasionally moderate conjunctivitis in gnotobiotic pigs, but the conjunctival infection is asymptomatic.Chlamydiae have been isolated from conjunctival swab specimens 1,8 and detected in conjunctival epithelium 8 from swine with conjunctivitis or keratoconjunctivitis, but the role of these organisms as significant corneal and/or conjunctival pathogens is unknown. Chlamydiae have been identified by an enzyme-linked immunosorbent assay in conjunctival swab specimens from clinically normal swine, leading to speculation that these organisms are not pathogens. 2 The objective of the present study was to determine whether a chlamydial strain recovered from growing and finishing swine with conjunctivitis or keratoconjunctivitis could cause the same infections in gnotobiotic pigs. This strain is resistant to sodium sulfadiazine but forms intracytoplasmic inclusions filled with glycogen in cell monolayers. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analyses indicate that the strain is a Chlamydia trachomatis-like organism and is very similar to but distinct from the C. trachomatis strains that cause conjunctivitis and sexually transmitted diseases in humans (Andersen et al., unpublished data). Materials and methodsIsolation of chlamydiae. A midwestern producer reported high prevalence of severe conjunctivitis, keratoconjunctivitis, and chemosis during the month of August in a herd of growing and finishing swine housed in relatively dust-free From the Veterinary Diagnostic Center, Department of Veterinary and Biomedical Sciences, University of Nebraska, Lincoln, NE 68583-0907 (Rogers), and the National Animal Disease Center, USDA, Agricultural Research Service, Ames, IA 50010 (Andersen).Received for publication May 18, 1998. modified open-front units. Cotton-tip conjunctival swab specimens collected from 25 affected pigs wer...

Growth and Development of Tetracycline-Resistant Chlamydia suis

“…Chlamydia pecorum and Chlamydia abortus (formerly "C. psittaci") have also been identified in swine. The two resistant strains examined here are very similar to C. trachomatis and have only recently been reclassified as C. suis (7,12,28).…”

“…However, they are very similar to C. trachomatis (28) and share several characteristics. The inclusion morphology of S45 and R19 observed in the absence of TET is generally similar to that of L2 inclusions (14).…”

Evaluation of lung function in pigs either experimentally or naturally infected with Chlamydiaceae

“…Other experimental trials challenging mainly upper airways (intranasally or intralaryngeally) and conjunctivae con¢rmed the pathogenicity of porcine isolates of C. trachomatis in gnotobiotic pigs (Rogers et al, 1996;Rogers and Andersen, 1999). Recently the authors have published an experimental model of inhalative aerogenous challenge with Chlamydia suis in conventionally raised pigs (Sachse et al, 2004).…”

Tetracycline Resistance inChlamydia suisMediated by Genomic Islands Inserted into the Chlamydialinv-Like Gene

“…Many different chlamydiae, including species causing serious diseases in reptiles, birds, and mammals, are important in infections of veterinary significance (21). Chlamydia suis is a pathogen that is widespread in farmed pigs and is associated with several chronic diseases, such as conjunctivitis and keratoconjunctivitis (25)(26)(27). The type strain of this species, strain S45, was isolated in Europe several decades ago and is tetracycline sensitive (Tc s ) (15).…”