Preliminary Study of an Immunochromatography Test for Serological Diagnosis of Canine Brucellosis

Abstract

ContentsThe most widely used screening test for the diagnosis of brucellosis in the dog is the rapid slide agglutination test in the presence of 2-mercaptoethanol (2ME-RSAT). The diagnosis is partially confirmed by the agar gel immunodiffusion test (AGID) and definitively confirmed by bacteriological isolation. Some chronic cases not detected by these tests may be detected by ELISA tests. The use of 2ME-RSAT in routine clinical practice requires a microscope and an experienced operator. An immunochromatographic diagnostic test for canine brucellosis (FASTest ® Brucella c., Megacor, Ho¨rbranz, Austria) has been recently released. In this study, we compared the diagnostic performance of the FASTest with those of 2ME-RSAT, AGID and ELISAs. Sera from 17 healthy dogs used as negative controls yielded negative results by FASTest, indicating a 100% specificity in this sample. Among 27 sera of dogs with acute or subacute brucellosis confirmed by B. canis isolation, all of which were positive by RSAT and ELISAs, the FASTest was positive in 24 cases and AGID in 23. In acute and subacute cases, the sensitivity of FASTest was 89%. Sera from six dogs with bacteriologically confirmed chronic brucellosis, which were positive by ELISAs but negative by 2ME-RSAT, were also tested; 1 was positive by FASTest and 4 were positive by AGID. These preliminary results indicate a good specificity of the FASTest (100% in this sample) but an unacceptable sensitivity as a screening test. In cases with chronic brucellosis, the sensitivity of the FASTest was lower than that of ELISAs but this assay could make a good intermediate test to be run after a positive RSAT and before running an AGID.

Evaluation of an Immunochromatographic Test to the Diagnosis of Canine Brucellosis Caused by Brucella canis

“…Wanke et al. () evaluated the performance of another commercial ICT kit (FASTest Brucella c., Megacor, Hörbranz, Austria) for the diagnosis of canine brucellosis by comparing the results of ICT with those of 2ME‐RSAT, AGID, ELISA and microbiological culture, and the results were similar to those observed in the present study.…”

“…The high specificity of the ICT (determined in Group 2) and the epidemiological condition of the dogs from Group 3 suggest that the positive results observed in the suspected dogs are the consequence of true infections. Wanke et al (2012) evaluated the performance of another commercial ICT kit (FASTest Brucella c., Megacor, H€ orbranz, Austria) for the diagnosis of canine brucellosis by comparing the results of ICT with those of 2ME-RSAT, AGID, ELISA and microbiological culture, and the results were similar to those observed in the present study.…”

Brucella canisinfection in dogs from commercial breeding kennels in Brazil

“…The serological tests available for the diagnosis of brucellosis in dogs are characterized by low values of diagnostic sensitivity, allowing the accurate detection of infected dogs predominately during the bacteremic period; therefore, blood culture is considered the definitive method for canine brucellosis diagnosis (Keid et al., , ; Wanke et al., ; Zoha & Carmichael, ). The detection of infected dogs after the bacteremic period is a great challenge as several laboratory tests and multiple biological samples from each animal may be necessary to confirm infection (Keid, Soares, Vasconcellos, Chiebao, Megid, et al., ; Keid, Soares, Vasconcellos, Chiebao, Salgado, et al., ; Zoha & Carmichael, ).…”

“…In this study, the diagnosis of brucellosis was based solely on the use of blood culture as positive results in this test are indicative of active infections and because of its high sensitivity when compared to the other laboratory tests available. Blood culture was proved to have a higher sensitivity when compared to the culture of other biological samples such as semen (Keid, Soares, Vasconcellos, Chiebao, Megid, et al., ), urine (Serikawa & Muraguchi, ) and vaginal discharge (Keid, Soares, Vasconcellos, Chiebao, Salgado, et al., ) and also when compared to the available serological tests (Keid et al., ; Wanke et al., ). PCR using blood showed a sensitivity similar or slight higher when compared to blood culture (Keid, Soares, Vieira, et al., ) and could be an alternative to the diagnosis.…”

“…Cross‐reactions were described between the B. ovis cell wall antigen and antibodies directed to Streptococcus faecalis , Staphylococcus epidermidis and Pseudomonas aeruginosa in agar gel immunodiffusion test (Carmichael, & Joubert, ) and with Bordetella bronchiseptica in tube agglutination test (George & Carmichael, ). Recent studies showed that agglutination tests using sera treated with 2‐mercaptoethanol, agar gel immunodiffusion test and immunochromatographic tests were highly specific, but a significant proportion of false‐negative results were observed in bacteremic dogs (Keid et al., , ; Wanke et al., ). Therefore, definitive diagnosis of infection must rely on the isolation of B. canis from suspected dogs using culture.…”