Patients with suspected bacterial infection at the time screening are eligible for this study. Patients may participate in this study if they are at least 18 years of age, and most participants will be receiving care at the clinical practices of the University of Pennsylvania. Up to 30 subjects will participate in two different imaging cohorts. The Biodistribution cohort will include up to 5 patients who will undergo a series of vertex to mid-thigh biodistribution [11C]trimethoprim PET/CT scans over a period of approximately 2 ½ hours. The Dynamic cohort will include up to 25 patients who will undergo approximately 60 minutes of dynamic scanning followed by up to 2 static skull base to mid-thigh scans imaging post injection of [11C]trimethoprim. Some subjects who may be selected clinically to undergo surgical or antibiotic treatment may undergo a second therapy may also undergo an optional second [11C]trimethoprim PET/CT after the initiation of therapy to collect pilot data on the changes in [11C]trimethoprim biodistribution and uptake with therapy, the timing of this scan may vary depending on the type of treatment the patient is receiving.

You may be eligible for this study if you meet the following criteria:

• Conditions: Infection
• Age: 18 years - 99 years
• Gender: All