Cats are potentially infected by three different hemoplasma species: Mycoplasma haemofelis (Mhf), 'Candidatus M. haemominutum' (Mhm), and 'Candidatus M. turicensis' (CMt), but only cats from the western USA have been assessed for DNA of CMt. Primers that amplify DNA of Mhf in a commonly used conventional PCR assay (cPCR) also amplify DNA of CMt and so it is possible additional cases have been missed. The objective of this study was to evaluate blood samples from cats in the USA for DNA of CMt.
Blood samples (n = 96) assessed in this study were selected solely on sample availability. DNA had been previously extracted, assayed in the cPCR, and stored at -80°C. DNA extracts were thawed, pipetted into individual wells of a 96 well plate, and shipped to the University of Bristol for assessment in a real time quantitative multiplex PCR assay (qPCR) that amplifies the DNA of CMt as well as 28S rDNA as an internal control.
Adequate DNA, as detected by the presence of plentiful 28S rDNA in the qPCR, was detected in 94 of the 96 samples, and 7 of these 94 samples contained DNA of CMt by qPCR. Of these 7 cats, 6 were male and 6 were anemic. CMt positive cats were from Alabama (3), Maryland (2), Colorado (1), and New Jersey (1). Estimated ages were 1-3 years (3), 10-12 years (3), and 15 years (1). A band of the appropriate size for Mhf or CMt was amplified from 4 of the 7 CMt positive cats in the cPCR. DNA of Mhm was amplified concurrently by cPCR from 5 of the 7 CMt positive cats.
The results suggest that CMt infection may be common in cats of the USA and that the cPCR used may be falsely negative in some cats with CMt infection. Future prevalence studies for hemoplasma infections in cats should utilize sensitive assays that differentiate between the three recognized species.