Infectious disease (ID) physicians are sometimes described as the detectives of medicine—decoding fevers, tracing strange symptoms, and helping unravel some of the most elusive medical cases. But what does an infectious disease doctor do, and why would someone be sent to an infectious disease doctor?
In the following conversation, Sueaen Daly, DO ‘21, and Elisa Mercando, DO ‘22, graduates of PCOM Georgia who will both soon begin infectious disease fellowships, discuss the investigative nature of the ID specialty, reflect on how their osteopathic training informs their approach, and share insights for future physicians considering the field.
Mercando: Our job is to determine whether an illness is caused by an infectious agent—bacteria, virus, fungi, or parasite—and what the best treatment is. That starts with deep history-taking and a full physical exam. We ask questions other physicians might not: Do you have pets? Have you traveled recently? Used injection drugs? You have to look everywhere for clues.
Daly: We get consulted by other specialties very often—surgery, nephrology, neurology, for example—because infection impacts every system. You’re coordinating care and deciding when antibiotics are needed, which ones, and for how long. Antibiotic stewardship is a big part of the job.
Daly: Pneumonia, urinary tract infections, catheter-related infections, diabetic foot ulcers, sepsis—you name it. We also see less common cases like tuberculosis, malaria, and HIV complications. Every hospital has different resistance patterns, so you have to stay sharp and tailor your treatment.
Mercando: We also treat osteomyelitis and endocarditis, and we get involved in post-operative infections and critically ill patients with resistant organisms. It’s intellectually demanding and highly collaborative.
Mercando: Through my internal medicine rotations, I realized I was most drawn to patients with infectious diseases—especially cases like bacteremia. They were the most intellectually engaging and felt like solving a mystery. Osteopathic training emphasizes how structure and function go hand-in-hand. We’re taught to consider how a patient’s anatomy, lifestyle, and emotional health affect outcomes, which is a big part of the detective work in infectious disease.
Daly: I loved the puzzle-solving of internal medicine, and ID stood out because you often get to treat the problem directly—not just manage it. Osteopathic medicine trains you to treat the whole person. That mindset is essential in ID, where a subtle historical detail or structural symptom can be a major clue. For example, Chapman points—which are areas of reflexive tenderness—can indicate referred pain from an infection and guide your diagnosis.
Chapman points are areas that feel like discrete nodules that usually indicate an area of visceral dysfunction. For example, the Chapman point for the bladder is located at the umbilicus (belly button) which might be found in a patient with a urinary tract infection. Sometimes patients with a UTI come in confused and unable to express what they’re feeling, but a DO might be able to feel a Chapman point in the umbilicus and consider a UTI as part of the differential diagnosis.
Daly: Try to do an infectious disease elective. The earlier you explore it, the more prepared you’ll be. Strong history-taking is your best friend, with physical exam skills a close second. And you have to enjoy learning—there’s always new research, emerging pathogens, and drug updates to keep up.
Mercando: Don’t be intimidated by the scope—you don’t have to know every bug and drug. It’s a collaborative field, and one of the most rewarding out there. Curiosity, collaboration, and discernment are key. You need to know how to narrow a differential diagnosis based on history and presentation, and you can’t be afraid to look something up or ask for a second opinion.
Daly: There are many fellowship options, especially in the Philadelphia area. Our programs are two years and include inpatient consults, outpatient clinics, microbiology labs, and sometimes even international rotations in travel or tropical medicine. Something I love is that you’re always learning—you’re helping people, but also solving mysteries. And the community in infectious disease is incredibly supportive.
Mercando: There’s a massive need for ID doctors, especially in the South. Some hospitals don’t have any, and patients get transferred or rely on telehealth. We both hope to eventually practice in underserved areas. Seeing someone get better—sometimes overnight—is incredible. It’s so gratifying to figure out the cause and fix it.
PCOM Georgia has been serving students and the community for 20 years as a branch campus of Philadelphia College of Osteopathic Medicine (PCOM), a private, not-for-profit, accredited institution of higher education established in 1899. Located in Suwanee (Gwinnett County), PCOM Georgia offers doctoral degrees in osteopathic medicine, pharmacy and physical therapy. Graduate degrees are offered in biomedical sciences, medical laboratory science and physician assistant studies. The campus joins PCOM South Georgia in Moultrie in helping to meet the healthcare needs of the state. Emphasizing "a whole person" approach to care, PCOM Georgia focuses on educational excellence, interprofessional education and service to the community. For more information, visit pcom.edu or call 678-225-7500. The campus is also home to the Georgia Osteopathic Care Center, an osteopathic manipulative medicine clinic, which is open to the public by appointment. For more information, visit pcomgeorgiahealth.org.
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