Fatal Pulmonary Hemorrhage Associated with RTX Toxin-Producing Actinobacillus Equuli Subspecies Haemolyticus Infection in an Adult Horse

Abstract

Abstract. A case of fatal pulmonary hemorrhage in a 6-year-old American Paint mare with a 2-week history of intermittent coughing, fever, and epistaxis is described. Significant macroscopic abnormalities at postmortem examination were restricted to the respiratory system, and microscopically, severe pulmonary hemorrhage with suppurative bronchopneumonia was found. Actinobacillus equuli subsp. haemolyticus was cultured from a transtracheal wash performed antemortem as well as from the lungs at necropsy. The presence of airwayassociated hemorrhage in conjunction with bacterial bronchopneumonia suggested endothelial damage caused by a locally elaborated bacterial toxin, possibly produced by the A. equuli strain isolated from the lungs. The objective of this report was to indirectly document the presence of hemolysin repeat in structural toxin (RTX) in the lungs of the reported mare. A real-time polymerase chain reaction (PCR) assay targeting the recently described aqx gene of A. equuli subsp. haemolyticus was established and validated. Transcriptional activity of the aqx gene was used as a surrogate method to document toxin production. Real-time PCR analysis of the transtracheal fluid and lung tissue of the affected mare confirmed the presence and the transcriptional activity of the aqx gene at the genomic (gDNA) and complementary DNA (cDNA) levels, respectively. The presence of pneumonia associated with hemorrhagic pulmonary fluid and the culture of large numbers of hemolytic A. equuli should prompt the clinician to consider endothelial damage caused by bacterial toxins.

Diet-Induced Alterations in Gut Microflora Contribute to Lethal Pulmonary Damage in TLR2/TLR4-Deficient Mice

“…Certain members of the Clostridium genus have well-established pathogenic properties and are capable of producing potent toxins (Lopetuso et al, 2013; Songer, 2004; Taur and Pamer, 2013), which may contribute to pulmonary alveolar endothelial damage and vascular permeability (Songer, 2004). Indeed, administration of bacterial toxin such as those from C. sordellii in mice causes similar lethal pulmonary damage as reported in this study (Bourke et al, 1994; Geny et al, 2007; Pusterla et al, 2008; Saeed et al, 2012). Whether certain members of the Clostridium genus are responsible for pulmonary damage in DKO mice remains to be demonstrated.…”

Pneumonia Caused byKlebsiellaspp. in 46 Horses

“…In our study, the presence of hemorrhagic nasal discharge was a negative prognostic indicator, with horses that presented with discharge having odds of not surviving 5 times higher than horses without discharge. Previously reported causes of hemorrhagic pneumonia include Actinobacillus spp., E. coli, and pulmonary infarction, although in the case report describing E. coli pneumonia, K. pneumoniae also was isolated and hemorrhagic nasal discharge was not described . In our study, 3 horses were coinfected with Actinobacillus spp.…”

Alterações patológicas em potros infectados por Actinobacillus equuli subsp. haemolyticus

“…Nos potros, o agente é frequentemente isolado de articulações, rins, pulmão e intestino (STEWART et al, 2002 (PLATT, 1973;COLLINS et al, 1994), peritonite (PLATT, 1973;COLLINS et al, 1994;PATTERSON-KANE et al, 2001), hemorragia pulmonar (PUSTERLA et al, 2008), endocardite valvular (AALBAEK et al, 2007), septicemia (PATTERSON-KANE et al, 2001) e abortos (SCHLAFER & MILLER, 2007). Os animais jovens quando infectados apresentam geralmente prostração e morte repentina (BAKER, 1972;PLATT 1973;STEWART et al, 2002).…”