Microbiology

Alfa Herrera

Alfa Herrera

Address: 3-401 BSB
Phone: (319) 335-7817
Email: alfa-herrera@uiowa.edu

Mentor: Patrick M. Schlievert, PhD

Undergraduate Institution: University of Illinois, Urbana-Champaign

Research Description

Staphylococcus aureus is a gram positive bacterium that asymptomatically colonizes 30-40% of the human population. S. aureus causes a variety of infections including superficial skin lesions, toxic shock syndrome, pneumonia, osteomyelitis, and infective endocarditis (IE). There are 100,000 cases of IE each year in the United States. S. aureus is the most commonly identified pathogen (31.4%) in patients with IE from healthcare settings. USA200 (Clonal Complex 30) strains of S. aureus are significantly associated with IE, all of which produce TSST-1 and β-toxin. My primary project focuses on determining how these virulence factors produced by USA200 strains are important for causing IE. In North America tstH is found in 88.5% of the S. aureus isolated from IE patients. TSST-1 (tstH) is a pyrogenic group I superantigen (SAg) shown to be a critical factor for the development of IE. β-toxin (hlb) is a sphingomyelinase that also functions as a biofilm ligase by cross-linking to itself in the presence of DNA, and is also cytotoxic to monocytes, lymphocytes, and PMNs in vitro. We hypothesize that TSST-1 may be important for the initiation and maintenance of IE vegetations, while β-toxin may contribute to vegetation growth. We will investigate the role that each factor plays independently or in cooperation with one another by using a rabbit model of IE.

 


Publication(s)

Held, N. L., Herrera, A. and Whitaker, R. J. (2013), Reassortment of CRISPR repeat-spacer loci in Sulfolobus islandicus. Environmental Microbiology. doi: 10.1111/1462-2920.12146

Cadillo-Quiroz H, Didelot X, Held NL, Herrera A, Darling A, Reno ML, Krause DJ, Whitaker RJ. Patterns of gene flow define species of thermophilic archaea. PLoS Biol. 2012 Feb;10(2):e1001265. Epub 2012 Feb 21.

Held NL, Herrera A, Cadillo-Quiroz H, Whitaker RJ. CRISPR associated diversity within a population of Sulfolobus islandicus. PLoS One. 2010 Sep 28;5(9). pii: e12988. PubMed PMID: 20927396; PubMed Central PMCID: PMC2946923.