Whether mice are an appropriate model for S. aureus infection and vaccination studies is a matter of debate, because they are not considered as natural hosts of S. aureus. We previously identified a mouse-adapted S. aureus strain, which caused infections in laboratory mice. This raised the question whether laboratory mice are commonly colonized with S. aureus and whether this might impact on infection experiments. Publicly available health reports from commercial vendors revealed that S. aureus colonization is rather frequent, with rates as high as 21% among specific-pathogen-free mice. In animal facilities, S. aureus was readily transmitted from parents to offspring, which became persistently colonized. Among 99 murine S. aureus isolates from Charles River Laboratories half belonged to the lineage CC88 (54.5%), followed by CC15, CC5, CC188, and CC8. A comparison of human and murine S. aureus isolates revealed features of host adaptation. In detail, murine strains lacked hlb-converting phages and superantigen-encoding mobile genetic elements, and were frequently ampicillin-sensitive. Moreover, murine CC88 isolates coagulated mouse plasma faster than human CC88 isolates. Importantly, S. aureus colonization clearly primed the murine immune system, inducing a systemic IgG response specific for numerous S. aureus proteins, including several vaccine candidates. Phospholipase C emerged as a promising test antigen for monitoring S. aureus colonization in laboratory mice. In conclusion, laboratory mice are natural hosts of S. aureus and therefore, could provide better infection models than previously assumed. Pre-exposure to the bacteria is a possible confounder in S. aureus infection and vaccination studies and should be monitored.

Oslerus osleri (O. osleri), found throughout the world, reportedly is the most common respiratory nematode of wild and domestic dogs. Oslerus osleri infestation was diagnosed in a 1.5-year-old Scottish terrier presenting with a seven-week history of progressive cough. Diagnosis was based upon visualization of characteristic lesions on bronchoscopic evaluation and recovery of O. osleri larvae from tracheal and bronchoalveolar lavage samples on fecal analyses. Therapy was successful using anti-inflammatory doses of prednisone (0.5 mg/kg body weight, per os [PO] every other day) and thiabendazole (35 mg/kg body weight, PO q 12 hrs for five days; then 70 mg/kg body weight, PO q 12 hrs for 21 days).

The incidence of Lyme disease is rapidly increasing in the United States. To assess the potential of transmission of the disease through blood transfusion, we studied the survival of Borrelia burgdorferi in blood products under blood bank storage conditions. Two units of whole blood, separated into red cells (RBCs), fresh-frozen plasma (FFP), and platelet concentrates (PCs), were inoculated with B. burgdorferi (strain B31) in concentrations of approximately 3000 organisms per mL of RBCs and FFP and 200 organisms per mL of PCs. Products were then stored under blood banking conditions and sampled at several storage times. The viability of the spirochete in blood components was determined by darkfield microscopic examination of cultures in modified Kelly's medium. The organism was shown to survive in RBCs (4 degrees C) and FFP (below -18 degrees C) for 45 days and in PCs (20-24 degrees C) for 6 days. The results of this study do not exclude the possibility of transmission of Lyme disease through blood transfusion.

Regardless of the preparation methods used in this study, bacterial populations capable of inducing wound infection remain on the hoof capsule.