Detection of novel chlamydiae in cats with ocular disease.
OBJECTIVE
To detect and characterize the full range of chlamydial infections in cats with ocular disease by use of polymerase chain reaction (PCR) assays, cytologic examination, immunohistochemical analysis, and evaluation of clinical information including status for feline herpesvirus-1 (FeHV-1).


METHODS
DNA extracted from 226 conjunctival samples obtained from cats with clinically diagnosed keratitis or conjunctivitis and 30 conjunctival samples from healthy cats.


METHODS
PCR assays for the 16S rRNA gene specific for the order Chlamydiales and a new Chlamydophila felis (formerly Chlamydia psittaci) species-specific 23S rRNA gene were performed. Seventy-four conjunctival samples were prepared with Romanowsky-type stain, grouped on the basis of inflammatory pattern, and screened for chlamydial inclusions by use of immunohistochemical analysis. Clinical information and FeHV-1 status were recorded.


RESULTS
26 (12%) specimens had positive results for the only known feline chlamydial pathogen, C felis. Surprisingly, an additional 88 (39%) were positive for non-C felis chlamydial DNA. Identification of non-C felis chlamydial DNA by direct sequencing revealed 16S rRNA gene sequences that were 99% homologous to the sequence for Neochlamydia hartmannellae, an amebic endosymbiont. Chlamydial prevalence was significantly higher in cats with ocular disease.


CONCLUSIONS
Application of a broad-range detection method resulted in identification of a new agent associated with ocular disease in cats. Finding chlamydia-like agents such as N hartmannellae in coinfections with their obligate amebic host, Hartmannella vermiformis, raises questions about the potential role of these microorganisms in causation or exacerbation of ocular disease in cats.
von Bomhard
Wolf
W
Department of Veterinary Pathology, Veterinary Faculty, University of Zurich, Zurich, Switzerland.
Polkinghorne
Adam
A
Lu
Zen Huat
ZH
Vaughan
Lloyd
L
Vögtlin
Andrea
A
Zimmermann
Dieter R
DR
Spiess
Bernhard
B
Pospischil
Andreas
A
D000818:Animals; D001483:Base Sequence; D002371:Cat Diseases / Q000175:diagnosis* / Q000382:microbiology / Q000473:pathology; D002415:Cats; D002689:Chlamydia / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D002690:Chlamydia Infections / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D003235:Conjunctivitis, Inclusion / Q000175:diagnosis / Q000473:pathology / Q000662:veterinary*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012329:RNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D012336:RNA, Ribosomal, 16S / Q000235:genetics / Q000302:isolation & purification; D012338:RNA, Ribosomal, 23S / Q000235:genetics / Q000302:isolation & purification; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid
D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012338:RNA, Ribosomal, 23S