Date of Award

1-1-2009

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Environmental Health Sciences

Content Description

1 online resource (xiv, 251 pages) : illustrations (some color), maps (some color)

Dissertation/Thesis Chair

Ellen Braun-Howland

Committee Members

Ellen Braun-Howland, Lloyd Wilson, Gordon Carlson, David Dziewulski, Syni-An Hwang, Kimberlee Musser, Roger Sokol

Keywords

antibiotics, coagulase-negative, mecA, methicillin, MRSA, Staphylococcus, Drug resistance in microorganisms, Staphylococcus aureus infections, Staphylococcus aureus

Subject Categories

Environmental Health | Microbiology | Public Health

Abstract

Ninety staphylococci carrying the mecA gene, including 17 strains of methicillin-resistant Staphylococcus aureus (MRSA), were isolated from environmental settings within New York State. Waterborne staphylococci harboring mecA were isolated from multiple sources: the Hudson River near a combined sewage overflow; urban streams; freshwater and marine beaches; a swimming pool; swimming pool decks; combined sewage; as well as wastewater treatment plant (WWTP) primary sewage influent, mixed liquor, aeration water, and final (unchlorinated) effluent. Environmental MRSA strains were isolated from beach water (n=3); swimming pool deck water (n=1); Hudson River water (n=2); combined sewage (n=3); as well as wastewater treatment plant mixed liquor (n=4), aeration water (n=2) and final effluent (n=2). MRSA strains were isolated from 3/75 (4%) of surface water samples collected from beaches near bathers. Characterization of MRSA isolates by pheno- and genotypic methods included antibiotic resistance testing, polymerase chain reaction amplification of portions of two genes encoding Panton-Valentine leukocidin, partial amplification and sequencing of variable regions within genes encoding staphylococcal protein A (spa) and hypothetical gene SACOL0058, and Pulsed-Field Gel Electrophoresis. The majority of environmental MRSA isolates resembled hospital-acquired MRSA strains in terms of genetic profiles. One MRSA isolate from swimming pool deck water, and another from WWTP aeration water, were indistinguishable from epidemic CA-MRSA (spa type t008; pulsotype USA300). Four Staphylococcus fleurettii isolates from surface water samples carried novel mecA variants, although mecI sequences were identical to that of pre-MRSA strain N315 (GenBank: BA000018.30). This is the first report of MRSA in swimming pool deck water, in river water at a combined sewer overflow discharge point, in surface water at freshwater beaches, and in WWTP final effluent, as well as the first extensive characterization of antibiotic resistance profiles among waterborne mecA-positive staphylococci. Study findings demonstrated that human exposure to MRSA may occur in more non-clinical settings than were previously known. This is also the first description of novel mecA variants in S. fleurettii, and the first report of cultivable S. fleurettii in surface water, indicating that the reported livestock colonizer is a potential reservoir of novel antibiotic resistance genomes that may be shared with S. aureus.

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