Antibody response to Panton-Valentine Leukocidin, a Staphylococcus aureus virulence factor, in pediatric patients from Texas Children's Hospital in Houston, Texas

Staphylococcus aureus is an important human pathogen of global health significance, whose frequency is increasing and whose persistence and versatility allow it to remain established in communities worldwide. An observed significant increase in infections, particularly in children with no predisposing risk factors or medical conditions, led to an investigation into pediatric humoral immune response to Panton-Valentine Leukocidin (PVL) and to other antigens expressed by S. aureus that represent the important classes of virulence activities. Patients who were diagnosed with staphylococcal infections were enrolled (n=60), and serum samples collected at the time of admission were analyzed using ELISA and Western blot to screen for immune response to the panel of recombinant proteins. The dominant circulating immunoglobulin titers in this pediatric population were primarily IgG, were specific, and were directed against LukF and LukS, while suppression of other important virulence factors in the presence of PVL was suggested. Patients with invasive infections (osteomyelitis, pneumonia or myositis) had higher titers against LukF and LukS compared to patients with non-invasive infections (abscesses, cellulitis or lymphadenitis). In patients with osteomyelitis, antibody responses to LukF and LukS were higher than antibody responses to any other virulence factor examined. This description of immune response to selected virulence factors of S. aureus caused by isolates of the USA300 lineage in children is novel. Antibody titers also correlated with markers of inflammation. The significance of these correlations remains to be understood.^

MOLECULAR AND GENOMIC BASED INSIGHTS INTO THE EVOLUTION OF ENTEROCOCCUS FAECIUM FROM COMMENSAL TO HOSPITAL-ADAPTED PATHOGEN

The basis for the recent transition of Enterococcus faecium from a primarily commensal organism to one of the leading causes of hospital-acquired infections in the United States is not yet understood. To address this, the first part of my project assessed isolates from early outbreaks in the USA and South America using sequence analysis, colony hybridizations, and minimal inhibitory concentrations (MICs) which showed clinical isolates possess virulence and antibiotic resistance determinants that are less abundant or lacking in community isolates. I also revealed that the level of ampicillin resistance increased over time in clinical strains. By sequencing the pbp5 gene, I demonstrated an ~5% difference in the pbp5 gene between strains with MICs <4ug/ml and those with MICs >4µg/ml, but no specific sequence changes correlated with increases in MICs within the latter group. A 3-10% nucleotide difference was also seen in three other genes analyzed, which suggested the existence of two distinct subpopulations of E. faecium. This led to the second part of my project analyzing concatenated core gene sequences, SNPs, the 16S rRNA, and phylogenetics of 21 E. faecium genomes confirming two distinct clades; a community-associated (CA) clade and hospital-associated (HA) clade. Molecular clock calculations indicate that these two clades likely diverged ~ 300,000 to > 1 million years ago, long before the modern antibiotic era. Genomic analysis also showed that, in addition to core genomic differences, HA E. faecium harbor specific accessory genetic elements that may confer selection advantages over CA E. faecium. The third part of my project discovered 6 E. faecium genes with the newly identified “WxL” domain. My analyses, using RT-PCR, western blots, patient sera, whole-cell ELISA, and immunogold electron microscopy, indicated that E. faecium WxL genes exist in operons, encode bacterial cell surface localized proteins, that WxL proteins are antigenic in humans, and are more exposed on the surface of clinical isolates versus community isolates (even though they are ubiquitous in both clades). ELISAs and BIAcore analyses also showed that proteins encoded by these operons bind several different host extracellular matrix proteins, as well as to each other, suggesting a novel cell-surface complex. In summary, my studies provide new insights into the evolution of E. faecium by showing that there are two distantly related clades; one being more successful in the hospital setting. My studies also identified operons encoding WxL proteins whose characteristics could also contribute to colonization and virulence within this species.

Philadelphia, Pennsylvania, Reed's map, 1774 (Raster Image) (Image 2 of 2)

This layer is a georeferenced raster image of the historic paper map entitled: Fac simile of Reed's map : to the honourable House of Representatives of the freemen of Pennsylvania this map of the city and liberties of Philadelphia with the catalogue of purchasers is humbly dedicated by their most obedient humble servant, Iohn Reed, James Smither sculp. Facsimile of a map originally published in 1774. Republished by Charles L. Warner in 1870. Scale [1:23,760]. Covers portions of Philadelphia, Pa. This layer is image 2 of 2 total images of the two sheet source map, representing the western portion of the map. The image inside the map neatline is georeferenced to the surface of the earth and fit to the Pennsylvania South State Plane Coordinate System NAD83 (in Feet) (Fipszone 3702). All map collar and inset information is also available as part of the raster image, including any inset maps, profiles, statistical tables, directories, text, illustrations, index maps, legends, or other information associated with the principal map. Cadastral map showing property boundaries, areas, lot numbers, and names of landowers. Includes features such as roads, drainage, and more. Includes inset: A ground plan of the city of Philadelphia. Also includes extensive text and index of landowners. This layer is part of a selection of digitally scanned and georeferenced historic maps from The Harvard Map Collection as part of the Imaging the Urban Environment project. Maps selected for this project represent major urban areas and cities of the world, at various time periods. These maps typically portray both natural and manmade features at a large scale. The selection represents a range of regions, originators, ground condition dates, scales, and purposes.

Water-quality assessment of Francis E. Walter reservoir, Luzerne and Carbon Counties, Pennsylvania /

"June 1983."

Visits of mercy; or The journals of the Rev. Ezra Stiles Ely, D.D. : Written while he was stated preacher to the hospital and alms-house, in the city of New York. : Vol. I [-II].

Includes two sermons by Ely.

The northern traveller, and northern tour, with the routes to the Springs, Niagara, & Quebec, and the coal mines of Pennsylvania, also, tour of New England.

The "Northern tour", Philadelphia, 1825, was the work of H.D. Gilpin.

U of M Ann Arbor Hospital

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965.

U of M Allopathic Hospital

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965. From the north or rear.

The University Hospital

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965.

The University Hospital

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965. Heating plant on left. On verso: on the right the Allopathic Hospital.

The University Hospital, Allopathic

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965. On verso: In the fall of 1897.

Hospital of 1890

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965.

Hospital of 1890

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965. On verso: From glass neg in possession of Stuart Thayer, Ann Arbor.

University Hospital

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965.

University Hospital, Catherine St., Allopathic Hospital

The eastern-most of two similar buildings built in 1891 on Catherine St. The western housed the Homeopathic Hospital from 1891-1900. This building housed the Allopathic Hospital (called Uiversity Hospital) from 1891-1900. (The Homeopathic Hospital had a straight north facade; this building a rounded north facade). From 1900-1925 it housed the Surgical Ward; 1925-1944 the East Convalescent Ward; 1944-1950, the Rapid Treatment Center; 1950-1965, the Institute for Social Research. It was removed in 1965.