Painful red nodules of the legs: a manifestation of chronic infection with gram-negative organisms

Severe and Progressive Cellulitis Caused by Serratia marcescens Following a Dog Scratch

Soft tissue infections occur in over 30% of patients with chemotherapy-induced neutropenia. Gram-positive bacterial infections predominate early in neutropenia, and likelihood of infection by resistant bacteria and fungi increases with prolonged neutropenia. Prior infections and exposures influence the risk of rare pathogens. A 55-year-old woman with chemotherapy-induced neutropenia was scratched on her forearm by a dog. She cleaned the wound with isopropanol and was treated empirically with amoxicillin-clavulanate. Over the next 4 days, she developed fever along with erythema, edema, and mild tenderness of the forearm without purulence or crepitus. She was hospitalized and received empiric treatment with intravenous vancomycin, piperacillin-tazobactam, tobramycin, and voriconazole. Despite therapy, her fevers persisted and the cellulitis progressed for over a week. After 10 days of hospitalization, her neutrophil count began to recover and a bulla developed at the wound site. Culture of the bullous fluid grew Serratia marcescens, and antibiotics were switched to cefepime based on susceptibility. She defervesced and showed substantial improvement of cellulitis within 48 hours and was discharged on oral ciprofloxacin. Serratia marcescens skin infections are rare, and this may be the first report of Serratia cellulitis associated with trauma from dog contact. This case highlights the need to consider unusual pathogens based on exposure history and immune status and to obtain cultures from fluid collections or tissue in cases of treatment-resistant soft tissue infections.

Pseudomonas skin infection: clinical features, epidemiology, and management

Pseudomonas aeruginosa is a Gram-negative bacillus that is most frequently associated with opportunistic infection, but which can also present in the otherwise healthy patient. The range of P. aeruginosa infections varies from localized infections of the skin to life-threatening systemic disease. Many P. aeruginosa infections are marked by characteristic cutaneous manifestations. The aim of this article is to provide a comprehensive synthesis of the current knowledge of cutaneous manifestations of P. aeruginosa infection with specific emphasis on clinical features and management. The ability of P. aeruginosa to rapidly acquire antibacterial resistance is an increasingly well recognized phenomenon, and the correct application of antipseudomonal therapy is therefore of the utmost importance. A detailed discussion of currently available anti-pseudomonal agents is included, and the benefits of antimicrobial combination therapy versus monotherapy are explored. Rapid clinical recognition of P. aeruginosa infection aided by the identification of characteristic cutaneous manifestations can play a critical role in the successful management of potentially life-threatening disease.

Spontaneous dermal abscesses and ulcers as a result of Serratia marcescens

Serratia sp have only rarely been reported as isolates from leg ulcers. We describe the case of a middle-aged man with a medical history significant for alcohol-induced cirrhosis who presented with rapidly progressive skin ulcers initially starting as purple nodules. These skin ulcers and underlying dermal abscesses were found to be a result of S marcescens, with the presumed portal of entry being a toe-web infection.