Sphingomonas paucimobilis Bacteremia in a Patient With Retropharyngeal Abscess.

Sphingomonas p aucimobilis is a nonfermenting gram-negative bacillus that is widely distributed in both community environments and hospitals. Various infections have been identified in humans, but most have been limited to case reports. When reported, it is most commonly nosocomial infections associated with contaminated hospital equipment such as indwelling catheters, ventilators, hemodialysis devices, and very rarely upper respiratory tract infections. We report an unusual presentation of S . paucimobilis infection. This case report describes a 59-year-old immunocompetent man who presented with a retropharyngeal abscess. Blood culture was positive for S . paucimobilis. The patient was treated for a total of 21 days of intravenous (IV) cefepime and oral (PO) metronidazole. He showed significant improvement and was discharged home with no medical sequelae.

Disease ecology across soil boundaries: effects of below-ground fungi on above-ground host-parasite interactions.

Host-parasite interactions are subject to strong trait-mediated indirect effects from other species. However, it remains unexplored whether such indirect effects may occur across soil boundaries and connect spatially isolated organisms. Here, we demonstrate that, by changing plant (milkweed Asclepias sp.) traits, arbuscular mycorrhizal fungi (AMF) significantly affect interactions between a herbivore (the monarch butterfly Danaus plexippus) and its protozoan parasite (Ophryocystis elektroscirrha), which represents an interaction across four biological kingdoms. In our experiment, AMF affected parasite virulence, host resistance and host tolerance to the parasite. These effects were dependent on both the density of AMF and the identity of milkweed species: AMF indirectly increased disease in monarchs reared on some species, while alleviating disease in monarchs reared on other species. The species-specificity was driven largely by the effects of AMF on both plant primary (phosphorus) and secondary (cardenolides; toxins in milkweeds) traits. Our study demonstrates that trait-mediated indirect effects in disease ecology are extensive, such that below-ground interactions between AMF and plant roots can alter host-parasite interactions above ground. In general, soil biota may play an underappreciated role in the ecology of many terrestrial host-parasite systems.