A comparison of real-time PCR and reverse line blot hybridization in detecting feline haemoplasmas of domestic cats and an analysis of risk factors associated with haemoplasma infections

BACKGROUND Three species of feline haemoplasma are recognised: Mycoplasma haemofelis (Mhf), 'Candidatus Mycoplasma haemominutum' (CMhm) and 'Candidatus Mycoplasma turicensis (CMt). This study compared a reverse line blot hybridization (RLB) assay for simultaneous detection of Mhf, CMhm with three separate quantitative real-time polymerase chain reaction (qPCR) assays used for diagnosis of Mhf, CMhm and CMt. The RLB and qPCR assays were applied to DNA extracted from blood samples collected from 154 cats from Trinidad and Tobago. RESULTS CMhm and Mhf DNA were detected using both RLB and qPCR. CMt DNA was detected by qPCR only. Comparing RLB and qPCR for the detection of CMhm DNA, 40 (26.3%) and 48 (31.6%) cats, respectively, were positive. The difference was more marked for Mhf, with RLB detecting a total of only 11 (7.2%) positive cats whereas qPCR detected 41 (27.0%) positive cats. Using qPCR as a gold standard, haemoplasma infected cats were more likely to be retrovirus positive (OR = 5.68, P = 0.02) and older (median age 5.5 years), than non-infected cats. In addition, CMhm positive cats were more likely to be male (OR = 3.4, P = 0.04). CONCLUSIONS Overall the qPCR was more sensitive than RLB. In addition, age (median 5.5 years) and retrovirus positivity were risk factors for infection with the feline haemoplasmas in this study population. Further studies on feline haemoplasma infections in cats are needed to determine the significance of detecting small amounts of haemoplasma DNA, feline retrovirus infection and other associated risk factors on the clinical manifestation of disease.