Cross-reactions in specific Brachyspira spp. PCR assays caused by "Brachyspira hampsonii" isolates: implications for detection.
An emerging novel spirochete in swine, provisionally designated "Brachyspira hampsonii," has been detected worldwide. It has been associated with swine dysentery and cannot be differentiated from B. hyodysenteriae, the classical etiologic agent of this disease, using standard phenotypic methods. We evaluated cross-reactions of "B. hampsonii" isolates recovered from avian species in some of the currently available species-specific polymerase chain reaction (PCR) assays for the identification of swine Brachyspira species. Ten avian "B. hampsonii" isolates recovered from wild waterfowl were used. No false-positive results were recorded with a B. pilosicoli-specific PCR based on the amplification of a fragment of the 16S rRNA gene. However, the percentage of false-positive results varied, with a range of 10-80%, in the evaluated B. hyodysenteriae-specific assays based on the amplification of the 23S rRNA, nox, and tlyA genes. Similarly, results of the B. intermedia-specific PCR assays yielded poor specificity, with up to 80% of the "B. hampsonii" isolates tested giving false-positive results. Finally, 2 "B. hampsonii" avian isolates yielded a positive result in a B. innocens- and B. murdochii-specific PCR. This result should be interpreted very cautiously as these 2 isolates could represent a recombinant genotype.
Department of Infectious Diseases and Epidemiology, Veterinary Faculty, University of León, León, Spain lallm@unileon.es.
Luis M
LM
Aller-Morán
Department of Infectious Diseases and Epidemiology, Veterinary Faculty, University of León, León, Spain.
F Javier
FJ
Martínez-Lobo
Department of Infectious Diseases and Epidemiology, Veterinary Faculty, University of León, León, Spain.
Pedro
P
Rubio
Department of Infectious Diseases and Epidemiology, Veterinary Faculty, University of León, León, Spain.
Ana
A
Carvajal
D000818:Animals; D001715:Bird Diseases / Q000382:microbiology*; D017400:Brachyspira / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D003429:Cross Reactions; D005777:Geese; D005838:Genotype; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology / Q000662:veterinary*; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013030:Spain; D013045:Species Specificity; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology
D012336:RNA, Ribosomal, 16S
PCR; cross-reactions; swine dysentery; “Brachyspira hampsonii”