Keynote Speaker
Mechanisms of genetic change and the natural history of pathogenesis in Haemophilus influenzae
Joshua Chang Mell, Ph.D.
Assistant Professor of Microbiology & Immunology
Drexel University College of Medicine

The main goal of the Mell lab is to understand how mechanisms of inheritance affect genetic
variation, and conversely, how genetic variation affects mechanisms of inheritance (i.e., “the
genetics of genetics”). Our primary model system is the human bacterial pathogen Haemophilus
influenzae, an important agent of ear infections (otitis media) in children, as well as lung infections
associated with chronic respiratory conditions. H. influenzae, like many other pathogens, is
naturally competent, able to actively transport environmental DNA through its cell membranes
and incorporate homologous molecules into its chromosomes. This pathway, called “natural
transformation,” is a major mechanism of gene transfer across bacteria and has a profound effect
on genome evolution, including spreading antibiotic resistances and other virulence
determinants. Our current research seeks to answer three major questions using a combination
of microbiology, molecular genetics, and genomics/bioinformatics approaches:

  1. What factors control transformation frequency across the genome?
  2. Can natural transformation be exploited to map pathogenesis genes?
  3. How do bacterial genomes change during the course of chronic infections?

Student Talks (4:00pm to 5:00pm)
4:00-4:20pm: “Toll-Like Receptors Dictate Microglia Responses to Beta-Coronaviruses”
Elijah Davis, PhD Candidate in the Navas-Martin lab, Drexel University College of Medicine
4:20-4:40pm: “The role of bacterial amyloid curli in Salmonella-induced Reactive Arthritis”
Kaitlyn Grando, PhD Candidate in the Tükel lab, Temple University Lewis Katz School of Medicine
4:40-5:00pm: “The role of the Kingella kingae lipopolysaccharide in galactan surface anchoring”
Nina Montoya, PhD Candidate in the St. Geme lab, University of Pennsylvania Perelman School of Medicine

5:15 – 6:15pm Keynote Speaker

Zoom link will be sent to branch members by email
Non-members can view the live stream via our EPAASM YouTube channel

Bobbi S. Pritt, MD
Chair, Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology
Mayo Clinic, Rochester, MN
What’s Bugging You? Ticks, Teamwork, and Emerging Pathogens
Tick-borne diseases are an important cause of morbidity and mortality in the United States. While well-known tick-borne diseases have significantly increased in number over the past decade, and have expanded into new geographical regions, we have also seen the discovery of new bacterial, viral and parasitic tick-borne pathogens that cause human disease. There is a significant need for education on which diseases are circulating in different regions in the United States and how they can be diagnosed in the laboratory. Dr. Bobbi Pritt will discuss her work in new tick-borne pathogen discovery including the identification and characterization of Borrelia mayonii, the second known cause of Lyme disease in the United States.

Dr Pritt’s lecture is now available on the EPAASM YouTube channel

Upcoming Meetings:

795th May 23rd, 2022: Student speakers at 4-5pm, Invited Speaker 5-6pm (Student Comm)

796th June 13th, 2022 Norman Willett Memorial Lecture: Invited Speaker 5-6pm (Education Comm)

Russell Vance, Ph.D.
Professor of Immunology and Molecular Medicine, HHMI Investigator
University of California, Berkeley

“Shigella pathogenesis: in vivo veritas”

Bacteria of the genus Shigella cause shigellosis, a severe gastrointestinal disease that is a major cause of diarrhea-associated mortality in humans. Mice are highly resistant to Shigella and the lack of a tractable physiological (oral infection) model of shigellosis has impeded our understanding of this important human disease. We discovered that resistance of mice to shigellosis is at least in part due to activation of the NAIP-NLRC4 inflammasome in intestinal epithelial cells. Mice lacking inflammasome responses are susceptible to Shigella flexneri and exhibit the major hallmarks of human shigellosis, including inflammatory diarrhea and bloody stools. We are now using this new mouse model to further delineate the host factors involved in Shigella pathogenesis. In this talk, I will describe the model, including some recent unpublished data.

5 – 6 pm, virtual meeting

The Vance Laboratory
We study the interactions between pathogens and the innate immune system.

Infection is a constant threat to all living things. Most of us are oblivious of this threat because our immune system does a remarkable job of eliminating infectious microbes before they cause symptoms. We are interested in understanding how the immune system detects the presence of infectious microbes. We use all the tools of modern molecular biology, biochemistry, and genetics to dissect the fundamental mechanisms that provide host defense. We are also interested in understanding the mechanisms by which pathogens evade host immunity and cause disease.

Zoom information will be emailed to branch members. Non- members can live stream the lecture on our branch YouTube page. (Note: video recording of this lecture will not be available)
Upcoming meetings:

794th April 25th, 2022: Bobbi S. Pritt, MD, Mayo Clinic, Rochester, MN

795th May 23rd, 2022: Student speakers at 4-5pm, Invited Speaker 5-6pm (Student Comm)

796th June 13th, 2022 Norman Willett Memorial Lecture: Invited Speaker 5-6pm (Education Comm)

Carrie Rosenberger, Ph.D.

Principal Scientist, Biomarker Discovery, Genentech, Inc.

A myeloid signature associated with COVID-19 severity is decreased by therapeutic blockade of IL-6 signaling

Severe viral and bacterial infections, including SARS-CoV-2, can trigger maladaptive inflammation and lung injury in some patients, leading to acute respiratory distress syndrome (ARDS) with a 30% mortality rate. COVID-19 presented an opportunity to test new therapies that may reduce disease progression from pneumonia to ARDS. Our reverse translation strategy aims to identify new targetable pathways by analyzing clinical samples to define patient subgroups that vary in disease progression or treatment response. As an example of our approach, we’ve identified a myeloid state in airway samples that is associated with severity in COVID-19 and ARDS and is driven by IL-6. This altered myeloid state is characterized by features of suppressor cell functionality, with low antigen presentation capacity and high expression of T cell-suppressive factors such as PD-L1 and IL-10. Blockade of IL-6 signaling by Anti-IL6R in a placebo-controlled clinical trial rapidly normalizes myeloid and T cell transcriptional states. This identifies IL-6 as a key driver of myeloid dysregulation associated with worse clinical outcomes in COVID-19 patients and provides insights into shared pathophysiological mechanisms in pneumonia caused by other pathogens. We are using single cell RNA-seq, proteomics, and genetic data from patient cohorts to develop strategies to target maladaptive inflammation and defining biomarkers to identify which ARDS patients have the greatest potential to benefit from novel drugs.

Zoom Meeting: 5-6pm (members will receive a separate email with link information)


793rd March 28th, 2022: Russell Vance, UC Berkeley, 5-6pm

794th April 25th, 2022: Bobbi Pritt, Mayo Clinic, 5-6pm

795th May 23rd, 2022: Student speakers at 4-5pm, Invited Speaker 5-6pm (Student Comm)

796th June 13th, 2022 Norman Willett Memorial Lecture: Invited Speaker 5-6pm (Education Comm)


EPAASM YouTube Channel (video recording of this lecture is not available)

Twitter: @EPAASMBranch

Please join us for the monthly meeting on January 24th, 2022 

Rebekah E. Dumm, PhD

CPEP Fellow in Medical and Public Health Microbiology

Hospital of the University of Pennsylvania and

Children’s Hospital of Philadelphia 

Clinical Utility of Broad-Range 16S rRNA gene PCR with Sequencing

Broad-range bacterial 16S rRNA gene PCR with sequencing (BRPS) is used to detect bacterial pathogens present in clinical specimens. BRPS has demonstrated utility in identifying the causative agent, particularly from normally sterile sites with high suspicion of infection, even when cultures are negative. The goal of this study was to review the experience at the Hospital of the University of Pennsylvania (HUP) with send-out testing to reference laboratories for BRPS, evaluating ways to improve clinical utilization of the test. This was accomplished by correlating the BRPS results with microbiology cultures and surgical pathology findings and using these features to predict high-yield samples and specimen types. This talk will also discuss optimal use cases and highlight some practical interventions for improving patient care through diagnostic stewardship.

Lecture 5 to 6pm

Zoom Meeting link will be emailed to Branch members

Watch Dr Dumm’s lecture on our YouTube Channel :