Pathogenesis of Streptococcus zooepidemicus infection after intratracheal inoculation in llamas

Christopher K. Cebra Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802.

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Jerry R. Heidel Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802.

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Margaret L. Cebra Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802.

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Susan J. Tornquist Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802.

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Bradford B. Smith Department of Veterinary Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331-4802.

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Abstract

Objectives—To test whether generalized Streptococcus zooepidemicus infection could be induced by intratracheal inoculation in llamas and to characterize this infection.

Animals—6 test and 3 control llamas.

Procedure—Test llamas received 1 of 3 dosages of S zooepidemicus by intratracheal injection, whereas control llamas received sterile culture medium. Physical examination variables and results of clinicopathologic analyses of blood, peritoneal fluid, and tracheal wash fluid were compared in test llamas between, before, and during the development of bacteremia and with control llamas. Bacteriologic culture was performed on all collected body fluids and tissue specimens that were collected at necropsy. Tissue specimens that were collected at necropsy were examined histologically.

Results—Infection induced fever, anorexia, and signs of depression. Five of 6 infected llamas developed specific signs of inflammation in the thorax or abdomen, bacteremia, neutrophilic leukocytosis with toxic changes and high band neutrophil cell counts, hyperfibrinogenemia, and high peritoneal fluid WBC counts and protein concentrations. On development of bacteremia, llamas had significant decreases in serum iron (from 118 ± 25 to 6 ± 4 µg/ml) and increases in serum glucose (from 131 ± 5 to 253 ± 48 mg/dl) concentrations.

Conclusions and Clinical RelevanceStreptococcus zooepidemicus spreads rapidly to other body compartments after intratracheal inoculation in llamas. Fever, anorexia, and signs of depression are the most consistent clinical signs, although other signs are possible. Clinicopathologic analysis of body fluids yields evidence of inflammation. Infection by S zooepidemicus can be proven by bacteriologic culture of body fluids before death or of tissue specimens after death. (Am J Vet Res 2000:61;1525–1529)

Abstract

Objectives—To test whether generalized Streptococcus zooepidemicus infection could be induced by intratracheal inoculation in llamas and to characterize this infection.

Animals—6 test and 3 control llamas.

Procedure—Test llamas received 1 of 3 dosages of S zooepidemicus by intratracheal injection, whereas control llamas received sterile culture medium. Physical examination variables and results of clinicopathologic analyses of blood, peritoneal fluid, and tracheal wash fluid were compared in test llamas between, before, and during the development of bacteremia and with control llamas. Bacteriologic culture was performed on all collected body fluids and tissue specimens that were collected at necropsy. Tissue specimens that were collected at necropsy were examined histologically.

Results—Infection induced fever, anorexia, and signs of depression. Five of 6 infected llamas developed specific signs of inflammation in the thorax or abdomen, bacteremia, neutrophilic leukocytosis with toxic changes and high band neutrophil cell counts, hyperfibrinogenemia, and high peritoneal fluid WBC counts and protein concentrations. On development of bacteremia, llamas had significant decreases in serum iron (from 118 ± 25 to 6 ± 4 µg/ml) and increases in serum glucose (from 131 ± 5 to 253 ± 48 mg/dl) concentrations.

Conclusions and Clinical RelevanceStreptococcus zooepidemicus spreads rapidly to other body compartments after intratracheal inoculation in llamas. Fever, anorexia, and signs of depression are the most consistent clinical signs, although other signs are possible. Clinicopathologic analysis of body fluids yields evidence of inflammation. Infection by S zooepidemicus can be proven by bacteriologic culture of body fluids before death or of tissue specimens after death. (Am J Vet Res 2000:61;1525–1529)

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