Use of a polymerase chain reaction assay to study response to oxytetracycline treatment in experimental Candidatus Mycoplasma haemolamae infection in alpacas.
OBJECTIVE
To develop a PCR assay for Candidatus Mycoplasma haemolamae (CMhl) infection in alpacas and use it to study the efficacy of oxytetracycline treatment and development of a subclinical carrier state.


METHODS
8 healthy adult alpacas.


METHODS
Alpacas initially had negative results for CMhl in blood samples via PCR assay and were experimentally infected with CMhl; 4 were treated with oxytetracycline, and 4 were not treated. All were monitored regularly via PCR assay, blood smear examination, PCV, rectal temperature, and physical examination. At 6 months after treatment, all alpacas were immunosuppressed by administration of dexamethasone and tested for CMhl.


RESULTS
7 of 8 alpacas had positive PCR assay results 4 to 6 days after experimental infection. When organisms were detectable on a blood smear, they were seen 2 to 6 days after positive results of PCR assay. Infection was often associated with mild anemia that was usually transient. No alpacas became hypoglycemic. Oxytetracycline treatment was not associated with faster clearance of organisms or resolution of anemia, and 4 of 4 treated alpacas still had positive results of PCR assay when immunosuppressed 6 months later; 0 of 3 nontreated alpacas had positive results of PCR assay following immunosuppression. Transient fever was detected in 3 alpacas during immunosuppression.


CONCLUSIONS
The PCR assay was more sensitive than blood smear examination for detection of infection. Clinical signs, anemia, and fever were not necessarily associated with infection. Oxytetracyline administration did not consistently clear CMhl infection. Although treated with oxytetracycline, infected alpacas remained chronic carriers.
Tornquist
Susan J
SJ
Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
Boeder
Lisa J
LJ
Cebra
Christopher K
CK
Messick
Joanne
J
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016470:Bacteremia / Q000097:blood / Q000188:drug therapy / Q000662:veterinary; D002161:Camelids, New World / Q000097:blood / Q000382:microbiology*; D002353:Carrier State / Q000382:microbiology; D017931:DNA Primers; D004269:DNA, Bacterial / Q000235:genetics; D009174:Mycoplasma / Q000235:genetics; D009175:Mycoplasma Infections / Q000097:blood / Q000188:drug therapy / Q000662:veterinary*; D010118:Oxytetracycline / Q000627:therapeutic use*; D016133:Polymerase Chain Reaction
D000900:Anti-Bacterial Agents; D017931:DNA Primers; D004269:DNA, Bacterial; D010118:Oxytetracycline