Melinda Mary Pettigrew, PhD

Professor of Epidemiology (Microbial Diseases); Associate Dean for Academic Affairs

Research Interests

Drug Resistance; Pneumonia; Respiratory Tract Infections; Infection Control; Pulmonary Disease, Chronic Obstructive

Research Organizations

School of Public Health: Center for Interdisciplinary Research on AIDS | Epidemiology of Microbial Diseases: Vaccine Group | YSPH Global Health Concentration

CPIRT - Pulmonary Infection Research and Treatment

Faculty Research

Global Health Initiative

Office of Cooperative Research

Research Summary

Professor Pettigrew's research focuses on pathobionts of the respiratory tract (e.g., Streptococcus pneumoniae and Haemophilus influenzae) and the growing public health threat of antibiotic resistance. Her current work utilizes a combined approach involving microbiology and infectious disease epidemiology to identify factors that influence whether pathobionts asymptomatically colonize or cause diseases such as pneumonia and exacerbations of chronic obstructive pulmonary disease (COPD). Additional projects focus on how disruptions of homeostasis in the respiratory and gastrointestinal microbiota influence colonization resistance, development of antibiotic resistance, and risk of hospital-acquired infections.

Extensive Research Description

My research focuses on Streptococcus pneumoniae and non-typeable Haemophilus influenzae. The bacteria that I study asymptomatically colonize the respiratory tract of 10-50% of healthy individuals. While asymptomatic colonization is far more common than disease, S. pneumoniae and H. influenzae are important causes of bacterial infections in children and adults (e.g., otitis media, pneumonia, and exacerbations of chronic obstructive pulmonary disease (COPD)). Moreover, these infections are frequently, and controversially, treated with antibiotics. We use state-of-the-art methods that integrate clinical epidemiologic, and laboratory studies to elucidate factors that tip the balance between asymptomatic bacterial colonization and disease.

Additional projects focus on how disruptions of homeostasis in the respiratory and gastrointestinal microbiota influence colonization resistance, development of antibiotic resistance, and risk of hospital-acquired infections. We use data and specimens from clinical epidemiologic studies and next-generation sequencing methods to address several key questions including: 1) How does the duration of antibiotic use impact the prevalence of antibiotic resistance genes in the respiratory and gastrointestinal microbiota? 2) How do antibiotic induced changes in the composition and diversity of the gastrointestinal microbiota contribute to antibiotic-associated diarrhea? and 3) How does the diversity and composition of the microbiota relate to risk of colonization, expansion, and infection due to antibiotic-resistant pathogens? Over the long-term, our research will help identify new methods to exploit protective mechanisms provided by an intact microbiota and lead to new interventions to prevent development of antibiotic resistance and hospital-acquired infections.


Selected Publications

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Contact Info

Melinda Mary Pettigrew, PhD
Office Location
Laboratory of Epidemiology and Public Health
60 College Street, Ste 720

New Haven, CT 06510
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Mailing Address
PO Box 208034
60 College Street

New Haven, CT 06520-8034