Companion animal staphylococcal isolate antibiograms were screened retrospectively to determine the frequency of methicillin-resistant (MR) infection by Staphylococcus aureus, Staphylococcus intermedius, and Staphylococcus schleiferi. Rates of MR were: S. aureus 35%, S. intermedius 17%, and S. schleiferi 40%. Frequency of isolation of methicillin-resistant S. aureus (MRSA) from dogs and cats was similar, whereas methicillin-resistant S. intermedius (MRSI) and methicillin-resistant S. schleiferi (MRSS) were significantly more common in dogs. MRSS was more commonly associated with superficial (skin and ear canal) infections, whereas MRSA was more commonly associated with deep infections. The MR strain resistance pattern to other classes of antibiotics was also investigated. MRSA was resistant to the most classes of antibiotics, followed by MRSI, while MRSS maintained the most favourable susceptibility profile. MR staphylococci may pose a significant risk to animal and public health. Therefore, to avoid selecting for resistant strains in cases of suspected staphylococcal infection, clinicians should consider culture and susceptibility testing early in the course of treatment.

No abstract

Immunity in the gastrointestinal tract is important for resistance to many pathogens, but the memory T cells that mediate such immunity are poorly characterized. In this study, we show that following sterile cure of a primary infection with the gastrointestinal parasite Trichuris muris, memory CD4+ T cells persist in the draining mesenteric lymph node and protect mice against reinfection. The memory CD4+ T cells that developed were a heterogeneous population, consisting of both CD62Lhigh central memory T cells (TCM) and CD62Llow effector memory T cells (TEM) that were competent to produce the Th type 2 effector cytokine, IL-4. Unlike memory T cells that develop following exposure to several other pathogens, both CD4+ TCM and TEM populations persisted in the absence of chronic infection, and, critically, both populations were able to transfer protective immunity to naive recipients. CD62LhighCD4+ TCM were not apparent early after infection, but emerged following clearance of primary infection, suggesting that they may be derived from CD4+ TEM. Consistent with this theory, transfer of CD62LlowCD4+ TEM into naive recipients resulted in the development of a population of protective CD62LhighCD4+ TCM. Taken together, these studies show that distinct subsets of memory CD4+ T cells develop after infection with Trichuris, persist in the GALT, and mediate protective immunity to rechallenge.

These results suggest that S. lugdunensis may cause invasive infections in companion animals, which should be treated with antimicrobials based upon susceptibility tests when available.

No abstract