Dr. Harrison's research focuses on the epidemiology and genomic epidemiology of vaccine-preventable and drug-resistant bacterial pathogens that are transmitted in the community and causes of hospital-associated infections (HAI's). Pathogens studied include Streptococcus pneumoniae, group B Streptococcus, Neisseria meningitidis, Escherichia coli O157:H7, Salmonella enterica, Clostridium difficile, Klebsiella pneumoniae, and Pseudomonas aeruginosa. He is the PI of the Microbial Genomic Epidemiology Laboratory (MiGEL), which conducts research on and provides training in genomic epidemiology and provides outbreak detection support to the Director of Infection Control at the University of Pittsburgh Medical Center (UPMC). MiGEL uses molecular epidemiologic tools, such as PFGE, MLST, MLVA and whole genome sequencing (WGS) to study emergence and transmission of these bacteria. More recently, Dr. Harrison has been studying the use of WGS and data mining of the electronic health record (EHR) and machine learning tools for enhanced outbreak detection in the hospital. He is also studying the utility of the perirectal microbiome to predict the risk of HAI's and transmission to other patients. Dr. Harrison has led a variety of NIH Fogarty International Center international training grants on bacterial diseases and HIV infection, both in Brazil and Mozambique.Dr. Harrison attends on the inpatient general infectious diseases consultation service at UPMC-Presbyterian Hospital. The service is commonly consulted for advice on diagnosis and treatment of infections including skin and soft-tissue infection; bacteremia and sepsis; central nervous system infections, such as bacterial meningitis, viral encephalitis, and brain abscess; osteomyelitis; necrotizing fasciitis; endocarditis and other cardiovascular infections; device-related and prosthetic infections; C. difficile infection; multidrug-resistant infections, and healthcare-associated infections.