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

Abstract

This study evaluated the performance of an immunochromatographic test (ICT) for the diagnosis of canine brucellosis caused by Brucella canis, comparing its results with that of the rapid slide agglutination test with and without the use of 2-mercaptoethanol and the agar gel immunodiffusion test (AGID). The microbiological culture, PCR and clinical examination were used as reference. According to the results obtained in clinical examination, blood culture, culture of semen and vaginal swab and PCR in blood, semen and vaginal swab, a total of 102 dogs were divided into three groups: B. canis-infected dogs (Group 1), B. canis-non-infected dogs (Group 2) and dogs with suspected brucellosis (Group 3). The diagnostic sensitivity of RSAT, 2ME-RSAT, AGID and ICT in Group 1 was, respectively, 75%, 37.5%, 27.8% and 89.58%. The diagnostic specificity of RSAT, 2ME-RSAT, AGID and ICT in Group 2 was, respectively, 91%, 100%, 100%, and 100%. In dogs with suspected brucellosis, 9.67% were RSAT positive, none was positive by 2ME-RSAT, 3.22% were AGID positive and 6.45% were ICT positive. The main drawback concerning canine brucellosis diagnosis is the lack of a highly sensitive serological assay to be used as a screening test to the rapid identification of infected animals. The ICT showed a high diagnostic specificity and a diagnostic sensitivity value greater than that observed in the RSAT, 2ME-RSAT and AGID. However, 10.41% of infected dogs had negative results by ICT. These dogs were positive by microbiological culture and/or PCR, indicating active infection and consequently a higher potential of spreading Brucella. Although rapid and simple to perform, the ICT lacked sensitivity to be used as a screening test.

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.…”

“…The laboratory diagnosis of the infection is difficult because of low sensitivity and specificity of the serological tests available. Unspecific reactions have been described especially in agglutination tests (Badakhsh, Carmichael, & Douglass, ; George & Carmichael, ; Keid, Diniz, Oliveira, Ferreira, & Soares, ; Keid et al., ). 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, ).…”

“…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.…”

<b>Desenvolvimento, padronização e validação de reação em cadeia pela polimerase (PCR) em tempo real para diagnóstico da brucelose canina</b>

“…Há vários métodos de diagnóstico disponíveis para a brucelose nos cães, baseados tanto em testes sorológicos quanto em métodos microbiológicos e moleculares, com desempenho variável em sensibilidade, especificidade, rapidez e praticidade na identificação de cães acometidos (KEID et al, 2007a,b,c;KEID et al, 2009;WANKE et al, 2012;KEID et al, 2015;LIMA, 2018).…”