Barbara Irene Kazmierczak, PhD, MD

Professor of Medicine (Infectious Diseases); Director, MD-PhD Program, Yale University; Professor of Microbial Pathogenesis

Research Interests

Bacterial Infections; Education, Medical, Graduate; Immunity, Innate; Microbiology; Pseudomonas; Biomedical Research; Host-Pathogen Interactions; Infectious Disease Medicine

Research Organizations

Internal Medicine: CPIRT - Pulmonary Infection Research and Treatment | Infectious Diseases

Microbial Pathogenesis

Discovery to Cure Internship

Office of Cooperative Research

Research Summary

Our laboratory is interested in how environmental or commensal organisms--bacteria with which we come into daily contact--can become pathogens capable of causing severe, life-threatening infections. To answer this question, we study the bacterial determinants that allow the bacterium Pseudomonas aeruginosa to move between soil and water reservoirs to human patients, as well as the host immune responses that usually keep it in check.  Recent projects also address strategies to discover new and re-purpose old antibiotics against this MDR pathogen.

We are also studying how the use of antibiotics alters the composition of the bacteria that reside in the human gut-- the "gastrointestinal microbiome"--and what consequences this has for an individual's ability to mount immune responses to vaccines and to infecting pathogens.

Specialized Terms: Pseudomonas aeruginosa; Innate immunity; Host-pathogen interactions; Mucosal immunity

Extensive Research Description

Dr. Kazmierczak studies opportunistic pathogens, with a primary emphasis on Pseudomonas aeruginosa. Her group is focused on understanding how microorganisms transition between commensal relationships with humans to causing disease. The following research projects are active in the laboratory.

  1. Regulation of genes involved in biofilm formation, Type 3 secretion and Type 6 secretion in Pseudomonas aeruginosa.
  2. Regulatory networks that control and coordinate pilus and flagellar assembly in response to environmental cues in Pseudomonas aeruginosa.
  3. Modulation of mammalian innate immune responses to Pseudomonas aeruginosa infection by the bacterial Type 3 secretion system apparatus and effectors.
  4. Single-cell analysis of Type 3 secretion system expression: how is phenotypic heterogeneity generated within a clonal population, and how does it affect fitness of a pathogen in the host?
  5. Novel approaches to understanding intrinsic antibiotic resistance and developing new antimicrobials.
  6. Acquisition of gut and airway microbiome populations in infants with Cystic Fibrosis and healthy controls: consequences for disease progression and development of inflammation.

Selected Publications

Full List of PubMed Publications

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Contact Info

Barbara Irene Kazmierczak, PhD, MD
Patient Care Location
Yale Infectious DiseasesYale New Haven Hospital
20 York Street

New Haven, CT 06510
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Lab Location
The Anlyan Center
300 Cedar Street, Ste S140

New Haven, CT 06519
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Office Location
The Anlyan Center
300 Cedar Street, Ste S169B

New Haven, CT 06519
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Mailing Address
Infectious DiseasesPO Box 208056
333 Cedar Street

New Haven, CT 06520-8056
Heterogeneous expression of virulence in Pseudomonas aeruginosa

A Type 3 secretion system transcriptional reporter driving sfGFP expression reveals variation among genetically identical bacteria exposed to conditions that induce this virulence system.