Investigating mechanisms of persistent Group B Streptococcus colonization after intrapartum antibiotic prophylaxis treatment

7/21/2021

Macy E. Pell, BS, PhD Candidate

about presenter

Macy Pell is a Ph.D. candidate in the lab of Dr. Shannon Manning at Michigan State University (MSU), currently studying pathogenesis mechanisms and genomic diversity of Group B Streptococcus (GBS). She is particularly interested in stress response and virulence mechanisms behind persistent infections of GBS during pregnancy. Macy received her Bachelor of Science degree from the University of Wisconsin-Madison in May of 2018 studying Microbiology. As an undergraduate, Macy investigated the population dynamics and diversity of Influenza viruses in non-human primate models in the lab of Dr. Thomas Friedrich. During the summers of her undergraduate career, Macy also performed research in Dr. Christopher Waters’ lab at MSU where she studied second-messenger signaling pathways in Vibrio cholerae and co-authored her first publication. Macy’s long-term research interests include understanding the virulence mechanisms of infectious microbes and the resulting impacts on human health. She plans to pursue a career in public health and infectious disease research to develop and improve upon disease prevention and awareness strategies.

Group B Strep International

7/21/2021 09:36:00 pm

Thank you for sharing the impressive work you are doing to study the mechanisms of persistent GBS colonization. Excellent presentation!

Macy Pell

7/22/2021 08:50:48 am

Thank you! I'm grateful for the opportunity to present my preliminary work at ICGBS2021!

Ameer Ahmad

7/21/2021 10:46:42 pm

But in presentation two days back it has been said that IAP will reduce the late onset disease as well.

7/22/2021 09:11:24 am

Thank you for your comment! IAP has been shown to significantly reduce the incidence of early-onset neonatal disease. We have not seen a significant reduction in cases of late-onset neonatal disease since the implementation of IAP treatment policies. There is currently no effective treatment for late-onset neonatal disease; therefore, the efforts to improve treatment and prevention strategies for GBS are crucial.

Roberta Creti

7/22/2021 06:23:37 am

Hi Macy, congratulation for your impressive presentation and black cat.
How and from where do some GBS strains gain virulence genes between visits?

7/22/2021 09:52:58 am

Thank you for your comment. Bubba the black cat has been an excellent co-worker while working remotely during the pandemic!

Great question! We believe the "gain" of these genes is mainly a factor of single nucleotide polymorphisms (SNPs), or insertion/deletion mutations. Our hypothesis is that certain SNPs are being selected for under these antibiotic-stress conditions that render the virulence gene "identifiable" (and perhaps functional) under our >80% sequence identity cutoff. I am currently performing core-genome SNP analyses on these isolate pairs to investigate these virulence gene changes further.

One possibility to consider is a lack of sequence coverage in the genomic location of a given virulence gene. For example, there may be poor coverage in the area of "gene X" in the visit 1 isolate, leading to an absence of detection, but good coverage across "gene X" in the visit 2 isolate, leading to detect the gene and then suggest "gene X" was "gained" at visit 2. I am currently mapping and aligning the reads to verify sequence coverage in these regions to rule out this caveat.

We hope that these further analyses will help to uncover key mutations associated with persistent colonization and particularly survival of GBS isolates in the presence of antibiotic stress.

Marti Perhach

7/22/2021 03:30:11 pm

In your study were you aware of any instances of persistent colonization in women with vaginitis symptoms that may have been attributable to GBS? GBSI often hears from women with chronic and persistent vaginitis symptoms after multiple treatments.

7/22/2021 06:49:46 pm

Thank you for your question! I have not looked into whether these women experienced vaginitis symptoms. I'm not sure if the cohort study collected this information but I will be sure to look into it. Thanks for bringing this information to my attention!

James Mcgregor mdcm

7/22/2021 08:57:40 pm

Thanks for you eloquently explication of this leading foundational work.questions: what about biofilm production, presence of L- forms, other commensals that promoted Gbs survival,? Or presence anti- host response factors? IgA ases?

7/23/2021 12:00:07 pm

Thank you for your comment and questions! These factors were not extracted in my analyses but I am planning on performing some functional assays, possibly looking into biofilm formation as this may be a component of persistent colonization. In one of my other projects I am investigating the impact of certain commensal species on GBS growth and survival, this work is still in the preliminary stages, but do feel free to connect if you are interested in following this work!

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Investigating mechanisms of persistent Group B Streptococcus colonization after intrapartum antibiotic prophylaxis treatment

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Investigating mechanisms of persistent Group B Streptococcus colonization after intrapartum antibiotic prophylaxis treatment

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