Detection of Streptococcus dysgalactiae subsp. equisimilis in equine nasopharyngeal swabs by PCR

Abstract

Streptococcus (S.) dysgalactiae subsp. equisimilis is responsible for severe diseases in humans, including primary bacteraemia, pneumonia, endocarditis, and toxic shock syndrome. Infection in some animal species can also occur, although a few studies have looked into cross-species infectivity. In horses, S. equisimilis is generally considered infrequent or opportunistic, but has recently been isolated from cases of strangles-like disease. Rapid and sensitive diagnostic techniques could enable epidemiological studies and effective investigation of outbreaks involving these bacteria. In this study, PCR protocols previously described in cattle and in humans to detect the species S. dysgalactiae and the subspecies equisimilis were evaluated to detect specific sequences in equine samples. For this purpose, 99 monolateral nasal swabs were collected from horses from stud farms with a history of S. equisimilis infection and were tested blindly by bacteriological isolation and by single and duplex PCR. DNA for PCR was extracted both from the colonies grown on agar media and from enrichment broth aliquots after incubation with nasal swab samples. S. equisimilis was identified by bacteriological isolation in 23 out of 99 swab samples, and PCR assays on these colonies were fully concordant with bacteriological identification (kappa statistic = 1.00). In addition, PCR of the enrichment broth aliquots confirmed the bacteriological results and detected S. equisimilis in 6 samples more than the bacteriological examination (kappa statistic = 0.84). The PCR protocols appeared to be reliable for the rapid identification of S. equisimilis in equine nasal swab samples, and could be useful for microbiological diagnosis.

Post-operative ocular infection due to Streptococcus dysgalactiae subspecies equisimilis

“…The DNA was extracted from one loopful of a pure streptococcal culture by lysozyme/proteinase K digestion [9]. The PCR mixture contained 2 l of the template (microbial) DNA, 10 pmol of each primer, 25 µl of Taq PCR mastermix (Qiagen GmbH, Hilden, Germany) and water up to 50 l total volume.…”

Beta-hemolyticStreptococcusspp. from horses

“…These publications describe studies either with a limited number of samples or addressing only a single type of organ/system/disease making it difficult to make conclusions regarding which organs and tissues are infected. 8,12,[14][15][16]19 In the case of S. equisimilis, information is very limited, and comprehensive epidemiological data is not available. 15 The goal of the present study was to have a largescale picture of these important horse pathogens in terms of tissue and/or organ distributions and susceptibility patterns against specific antimicrobials from the years 2000 to 2010.…”

“…12 A study published in 2007 described the isolation of this bacterium from horses with chronic upper respiratory disease 14 and from nasopharyngeal swabs. 15 All of these publications were based on either a limited number of isolates or addressing only a single system, which did not paint a full picture of S. equisimilis. Furthermore, many laboratories do not differentiate β-hemolytic streptococci.…”

Soft tissue infection caused by Streptococcus dysgalactiae subsp. equisimilis possessing group Aantigen: a and review of the literature

“…Kawata et al [73] discovered no streptokinase activity on human plasminogen in any of 11 SDSE strains isolated from pigs, such activity being one of the most important distinctive features of this bacterium [1]. Due to lack of data, it is not yet certain whether animals participate in transmission of that microorganism to people [70]. The available literature gives no documented cases of zoonotic infections, in contrast with S. equi subsp.…”