Chlamydophila infection in a cat
Chlamydophila felis (previously known as Chlamydia psittaci var. felis) is an obligate intracellular bacterium, which grows in the cytoplasm of epithelial cells, leading to production of inclusion bodies. After reclassification of the order Chlamydiales in 1999, the family Chlamydiaceae is now divided into two genera namely, Chlamydia and Chlamydophila (Everett et al., 1999). Chlamydophila felis belongs to the genus Chlamydophila.
Chlamydophila felis is a Gram-negative rod-shaped coccoid bacterium with a cell wall that lacks peptidoglycan. It is known as a obligate intracellular parasite with incapability of autonomous replication. Since it is unable to survive outside the host, transmission needs close contact between cats. It is believed that ocular secretions are the most favorable body environment for infection. Cats under age of 1 are mostly affected. This is the infectious organism associated with conjunctivitis (conjunctiva is the primary target) and/or respiratory tract disease (pneumonia). Ocular involvement is as such that unilateral (gradually progress to bilateral) conjunctivitis with extreme hyperaemia of the nictitating membrane, blepharospasm and ocular discomfort. Other clinical signs of infection with Cp. felis, in cats, are sneezing, transient fever, inappetence, weight lost, nasal discharge, and lethargy. We should bear in mind that most infected cats remain in good body condition and continue to eat adequately. The disease may be complicated by co-infection with other microorganisms. Feline chlamydiosis is more common in multi-cat environments, particularly breeding catteries. So the prevalence of infection may therefore be higher among pedigree cats.
Case study:
A 3-year domestic short-haired cat was presented to the clinic with ocular discomfort (noted epiphora, intermittent blepharospasm, redness and swelling of the conjunctiva, developed hamasa and grey to green secretions). The animal was restrained on examination table for sampling and the eye was cleaned with a cotton swab to remove mucosal discharge before sample was taken. Conjunctival sample (one commercial swab from the infected eye) was obtained by reflecting the eyelid and rolling swab across the conjunctiva. In the laboratory, the swabs were applied by rolling motion onto the surface of microscopic slides and then fixed by methanol followed by Wright staining.
Results:
Flat cells of the cornea showed the cytoplasm from slightly basophilic to suboccipital, inclusions, and signs of degeneration. There were many inflammatory cells, mainly neutrophils, in the cytological smear. Chlamydophila felis causes neutrophilic inflammation in the early stages of the disease, with mononuclear cells (macrophages) that appear as the process of chronicles.
In some cats, the smear was dominated by lymphocytes, and this inflammation was interpreted as lymphocytic. However, caution should be considered since these lymphocytes may represent normal follicular tissue, and not lymphocytic inflammation.
Basophilic (dark blue color) rounded cytoplasmic inclusions in the flat cell of the cornea were interpreted as intermediate bodies of Chlamydophila felis.
Treatment:
· Systemic antibiotics are more efficacious than topical antibiotics.
· Tetracyclines are the antibiotics of choice: doxycycline should be given for at least 3 weeks, i.e. 2 weeks beyond resolution of clinical signs.
· Amoxycillin-clavulanate (especially for young kittens) or fluoroquinolones are alternative choices.
· In multi-cat households it may be necessary to treat all cats until clinical signs have resolved, and then consider vaccination.
· Single housing and routine hygiene measures should be adequate to help control the spread of infection.
After 15 days into the treatment.
Conclusion:
The gold standard for the diagnosis of chlamydia is PCR, but the duration of this study is not always convenient in the clinical practice of a veterinarian. With an obvious cytological diagnosis, it is possible to early prescribe the correct treatment, which avoids unnecessary polypragmasia, which is especially important for young patients. With a difficult cytological diagnosis, PCR is considered as a diagnostic method of choice. Thus, cytological examination is a convenient, non-invasive, easily feasible method, which is suitable for rapid diagnosis of chlamydial conjunctivitis in cats.