Follicular Conjunctivitis due to Chlamydia felis—Case Report, Review of the Literature and Improved Molecular Diagnostics

Abstract

A 29-year-old woman presented with unilateral, chronic follicular conjunctivitis since 6 weeks. While the conjunctival swab taken from the patient’s eye was negative in a Chlamydia (C.) trachomatis-specific PCR, C. felis was identified as etiological agent using a pan-Chlamydia TaqMan-PCR followed by sequence analysis. A pet kitten of the patient was found to be the source of infection, as its conjunctival and pharyngeal swabs were also positive for C. felis. The patient was successfully treated with systemic doxycycline. This report, which presents one of the few documented cases of human C. felis infection, illustrates that standard PCR tests are designed to detect the most frequently seen species of a bacterial genus but might fail to be reactive with less common species. We developed a modified pan-Chlamydia/C. felis duplex TaqMan-PCR assay that detects C. felis without the need of subsequent sequencing. The role of chlamydiae-specific serum antibody titers for the diagnosis of follicular conjunctivitis is discussed.

Occurrence of Chlamydiaceae and Chlamydia felis pmp9 Typing in Conjunctival and Rectal Samples of Swiss Stray and Pet Cats

“…Since C. felis has poor environmental persistence, direct contact is needed for transmission [ 24 , 52 ]. It has been shown in the past that higher positivity rates could be associated with certain environmental risk factors such as outdoor access and living in a multi-cat environment, which increases the number of contacts between cats [ 22 , 44 , 46 ]. Halánová et al confirmed that a higher density of animals is most likely associated with higher chlamydial infection rates, and, according to Hwang et al, the prevalence of pathogens that are transmitted through direct contact is higher in areas where stray cats are being fed and therefore gather in groups [ 46 , 53 ].…”

“…Nevertheless, it has also been detected in dogs and was recently found in a free-ranging Eurasian lynx suffering from conjunctivitis [ 1 , 12 , 15 , 16 ]. Zoonotic transmissions are rarely reported, except for a few cases in which C. felis was found to be the cause of keratoconjunctivitis or follicular conjunctivitis in men [ 19 , 20 , 21 , 22 ], demonstrating its potential risk for zoonotic infections for humans with close contact to diseased animals in particular [ 23 ].…”

Chlamydiaceae: Diseases in Primary Hosts and Zoonosis

“…Conjunctivitis in human has previously been found in a case report involving an HIV-positive patient whose infection was traced back to a personal pet kitten which tested positive for non- trachomatis Chlamydia [142]. A similar case was recently reported in a woman who contracted unilateral chronic conjunctivitis from her C. felis -positive kitten [143]. Cases such as these are rare, but contribute to the increased likelihood of a threat of zoonosis.…”

“…Currently, porcine are the only known natural host. The zoonotic transmission of C. suis has been described among farmers in the porcine slaughterhouse through screening, although there is no clear signs of a symptomatic infection [87,88,89,142,143]. The isolation of a tetracycline-resistant strain of C. suis has raised considerable concerns within the porcine farming industry, especially regarding the fear of horizontal transfer of the tetracycline resistant Tet (C) gene to other human chlamydial pathogens [160].…”

Detection of Chlamydiaceae and Chlamydia-like organisms on the ocular surface of children and adults from a trachoma-endemic region

“…caviae and C . felis in human eyes 19 , 66 , 67 . In our study, one sequence obtained in the aTT group and one in the cTF group demonstrated highest homology to C .…”