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Introduction
Skills and Expertise
Additional affiliations
August 2008 - present
July 2006 - July 2008
January 2003 - May 2006
Education
August 2000 - May 2006
August 1997 - August 2000
Publications
Publications (56)
During decomposition, flies interact with the remains to lay eggs and acquire nutrients, and in the process, they bring their microbes with them. While it is known that flies have their own unique core microbiome, it is not known if flies associated with human cadavers have a different core microbiome. Differences in the fly microbiome may influenc...
Microbes are known to facilitate vertebrate decomposition, and they can do so in a repeatable, predictable manner. The succession of microbes in the skin and associated soil can be used to predict time since death during the first few weeks of decomposition.
Death investigations often include an effort to establish the postmortem interval (PMI) in cases in which the time of death is uncertain. The postmortem interval can lead to the identification of the deceased and the validation of witness statements and suspect alibis. Recent research has demonstrated that microbes provide an accurate clock that st...
Decomposition is a complex process with inputs from several interacting biotic and abiotic components. A full understanding of how these factors influence the ecology of decomposition is crucial for helping law enforcement and forensic personnel. Although it has long been known that microbes play a role in decomposition, they have historically rema...
Salmonella is a common cause of foodborne illness within the United States with the severity of the infection being a factor of both the age and overall health of the infected individual. The nematode worm Caenorhabditis elegans has proven to be a useful model to study infection dynamics of pathogenic bacteria, including Salmonella enterica, and it...
Infection caused by Salmonella is a worldwide health problem. Approximately 95% of cases of salmonellosis are associated with consumption of contaminated foods. There are over 2600 identified serotypes of Salmonella with a smaller number associated with disease. Many Salmonella contain pathogenicity islands scattered throughout their genomes that e...
The Southeast Texas Applied Forensics Science (STAFS) facility is one of five US centers dedicated to studying human decomposition. As cadavers decompose, they pass through five recognizable stages, with microorganisms and insects driving the initial “wet” stages. Microbiologically, cadavers decompose first from the inside out and shift from aerobi...
Vertebrate corpse decomposition provides an important stage in nutrient cycling in most terrestrial habitats, yet microbially
mediated processes are poorly understood. Here we combine deep microbial community characterization, community-level metabolic
reconstruction, and soil biogeochemical assessment to understand the principles governing microbi...
Human decomposition is a process marked by events categorized into five stages. These stages occur as a fluid procession rather than through precise demarcation of events and may lead to cadavers experiencing multiple stages of decomposition at once. Previous studies have investigated biodiversity of necrophagous bacteria and insects at predefined...
The Human Microbiome Project brought attention to the community of organisms that live and thrive in and on the bodies of humans. While it is important to understand the microbiome as it relates to human health, it is just as important to understand once human life has ceased and the microbial communities are allowed to proliferate over the course...
Decomposition is a dynamic ecological process dependent upon many factors such as environment, climate, and bacterial, insect, and vertebrate activity in addition to intrinsic properties inherent to individual cadavers. Although largely attributed to microbial metabolism, very little is known about the bacterial basis of human decomposition. To ass...
Flies are important members of the decomposition ecosystem and can be important evidence of death investigations when the time since death is questioned. Because flies arrive during the earliest stages of decomposition and have been recorded colonizing the corpse within minutes of death, they may be significant in establishing a cadaver-specific mi...
Flies are important members of the decomposition ecosystem and can be important evidence of death investigations when the time since death is questioned. Because flies arrive during the earliest stages of decomposition and have been recorded colonizing the corpse within minutes of death, they may be significant in establishing a cadaver-specific mi...
The important role insects have during the decomposition process and in estimating the post-mortem interval in forensic investigations is well established. Among the first colonizers of a corpse, sometimes within minutes of death, flies may play an important role in the establishment of a cadaver-specific microbiome and affect the succession of a c...
Salmonella enterica is a leading cause of bacterial foodborne illness worldwide. A wide range of molecular subtyping methods have been developed for the characterization of Salmonella isolates, with the goal of identifying the likely sources of infections. This chapter provides a broad overview of the various molecular subtyping methods available f...
Human decomposition is a dynamic process that is influenced by both abiotic and biotic factors. Measuring these influences, in particular abiotic factors, on the decomposition process is often a challenge for scientists. Recently, researchers have turned to the use of advanced remote sensing technologies in forensic investigations. In this study, a...
Human decomposition is a mosaic system with an intimate association between biotic and abiotic factors. Despite the integral role of bacteria in the decomposition process, few studies have catalogued bacterial biodiversity for terrestrial scenarios. To explore the microbiome of decomposition, two cadavers were placed at the Southeast Texas Applied...
Salmonella enterica serovar Heidelberg (S. Heidelberg) can cause foodborne illness in humans following the consumption of contaminated meat and poultry products. Recent studies from our laboratory have demonstrated that certain S. Heidelberg isolated from food-animal sources harbor multiple transmissible plasmids with genes that encode antimicrobia...
A number of the members of the family Enterobacteriaceae can serve as human and animal pathogens, causing a wide range of nosocomial, zoonotic, and foodborne illnesses. The ability to characterize these microorganisms to determine the relationship between members of a particular species is important to develop strategies to limit bacterial disease....
Salmonella enterica serovar Heidelberg is among the most detected serovars in swine and poultry, ranks among the top five serotypes associated with human salmonellosis and is disproportionately associated with invasive infections and mortality in humans. Salmonella are known to carry plasmids associated with antimicrobial resistance and virulence....
Writing is a learning activity, as well as a communication skill. Many instructors recognize the value of writing as a learning tool but struggle to develop effective writing assignments. Instructors are generally pressed for time during lecture due to the necessity to deliver content and, therefore, cannot dedicate time necessary to teach science...
Avian pathogenic Escherichia coli (APEC) cause colibacillosis, a disease which is responsible for significant losses in poultry. Control of colibacillosis is problematic due to the restricted availability of relevant antimicrobial agents and to the frequent failure of vaccines to protect against the diverse range of APEC serogroups causing disease...
Salmonellosis is of public health concern, accounting for about a quarter of all bacterial foodborne infections. According to the CDC, Salmonella enterica serovar Typhimurium is the most common Salmonella serotype reported. Of great concern is the possession and dissemination of antimicrobial resistance among Salmonella strains. Many antimicrobial...
Members of Salmonella are able to infect a wide range of hosts with some subspecies and serovars being host-specific while others are wide host range organisms. Salmonella is most commonly associated with humans, food animals (bovine, swine and poultry) and reptiles such as turtles, lizards, and iguanas. The exact nature of this diversity towards h...
Introduction Cell Wall Synthesis Inhibiting Drugs Protein Synthesis Inhibiting Drugs Nucleic Acid Synthesis-Inhibiting Drugs Metabolic Pathway-Inhibiting Drugs Chemical Disinfectants References
Schwyn and Neiland developed a universal siderophore assay using chrome azurol S(CAS) and hexadecyltrimethylammonium bromide (HDTMA) as indicators. In Schwyn and Neiland’s original paper, the procedure given for making CAS agar is written in general terms and can be difficult to follow, especially for an individual who has limited experience making...
Prevalence of ColV plasmid-associated genes among
Salmonella
isolates.
(DOC)
Prevalence of ColV plasmid-associated genes among
S
. Kentucky isolates.
(DOC)
Salmonella enterica continues to be a significant cause of foodborne gastrointestinal illness in humans. A wide variety of Salmonella serovars have been isolated from production birds and from retail poultry meat. Recently, though, S. enterica subsp. enterica serovar Kentucky has emerged as one of the prominent Salmonella serovars isolated from bro...
Seventy-eight Salmonella enterica serovar Heidelberg isolates from humans were tested for antimicrobial susceptibility, resistance genes, and plasmids and genotyped by pulsed-field gel electrophoresis (PFGE). Most (88%) contained plasmids, and 47% were resistant to antimicrobials. The overall results were compared to those of previous S. Heidelberg...
Escherichia coli has been used as an indicator organism for fecal contamination of water and other environments and is often a commensal organism
in healthy animals, yet a number of strains can cause disease in young or immunocompromised animals. In this study, 281 E. coli isolates from bovine, porcine, chicken, canine, equine, feline, and other ve...
Gram-negative bacterial foodborne pathogens are a worldwide cause of morbidity and mortality. The ability to carry out epidemiological investigations to determine the primary sources of bacterial contamination is important to improve public health. Multiple methods are available for bacterial source tracking and to determine the distribution of pat...
Salmonella enterica serovars Dublin, Choleraesuis and Pullorum are host-adapted serovars that cause disease primarily in cattle, swine and poultry, respectively. In addition, serovars Dublin and Choleraesuis are important human pathogens that are disproportionately associated with severe invasive infections that require antimicrobial therapy. Becau...
Fifty-eight Salmonella enterica serovar Heidelberg isolates isolated from food animals were tested for antimicrobial susceptibilities and further characterized for select antimicrobial resistance genes, plasmid carriage, class 1 integrons, and genetic relatedness using pulsed-field gel electrophoresis (PFGE). Seventy-two percent of isolates display...
Salmonella enterica serovar Heidelberg strains are frequently associated with food-borne illness, with recent isolates showing higher rates of resistance to multiple antimicrobial agents. One hundred eighty S. enterica serovar Heidelberg isolates, collected from turkey-associated production and processing sources, were tested for antimicrobial susc...
Salmonellosis is the second leading cause of bacterial foodborne illness in the United States, and the great majority of these infections are associated with the consumption of products such as meat, poultry, eggs, milk, seafood, and fresh produce contaminated with Salmonella. The per capita consumption of meat and poultry in United States has incr...
Salmonellosis is a worldwide health problem; Salmonella infections are the second leading cause of bacterial foodborne illness in the United States. Approximately 95% of cases of human salmonellosis are associated with the consumption of contaminated products such as meat, poultry, eggs, milk, seafood, and fresh produce. Salmonella can cause a numb...
Salmonella enterica serotype Newport is an important cause of salmonellosis, with strains increasingly being resistant to multiple antimicrobial
agents. The increase is associated with the acquisition of multiple resistance genes. This study characterizes the genetic
basis of resistance of serotype Newport isolates collected from veterinary sources...
Colibacillosis, caused by avian pathogenic Escherichia coli (APEC) is a major problem for the poultry industry resulting in significant losses annually. Previous work in our lab and by others has shown that the increased serum survival gene (iss) is a common trait associated with the virulence of APEC. This gene was first described for its contribu...
Escherichia coli strains that cause disease outside the intestine are known as extraintestinal pathogenic E. coli (ExPEC) and include human uropathogenic E. coli (UPEC) and avian pathogenic E. coli (APEC). Regardless of host of origin, ExPEC strains share many traits. It has been suggested that these commonalities may enable APEC to cause disease i...
To confirm the presence of Iss and Bor on the outer membrane of Escherichia coli using Western blots of outer membrane protein (OMP) preparations and fluorescence microscopy, and explore the use of fluorescence microscopy for the detection of avian pathogenic E. coli (APEC) and diagnosis of avian colibacillosis.
Knockout mutants of iss and bor were...
Colibacillosis accounts for annual multimillion dollar losses in the poultry industry, and control of this disease is hampered by limited understanding of the virulence mechanisms used by avian pathogenic Escherichia coli (APEC). Previous work in our laboratory has found that the presence of the increased serum survival gene (iss) is strongly assoc...
Colibacillosis accounts for significant losses to the poultry industry, and control efforts are hampered by limited understanding of the mechanisms used by avian pathogenic Escherichia coli (APEC) to cause disease. We have found that the presence of the increased serum survival gene (iss) is strongly associated with APEC but not with commensal E. c...
Control of avian colibacillosis is hampered by lack of easily identifiable markers for virulent Escherichia coli. Resistance to serum complement appears to be a widespread trait of virulent avian E. coil, suggesting that bacterial factors promoting survival in serum may be useful in discriminating between virulent and avirulent isolates. Such disti...
This study was designed to compare virulence factors of cellulitis-derived Escherichia coli to colisepticemic E. coli in order to clarify whether E. coli associated with cellulitis comprise a unique subset of pathogenic E. coli. Isolates were tested for serotype, capsule, aerobactin production, colicin production, the presence of the iss gene, and...
Projects
Projects (2)
Detecting the postmortem interval, or the time since death, in forensic investigations is crucial for multiple reasons, such as estimating when the victim passed and validating the whereabouts of suspects, for example. Currently, fields such as forensic entomology and forensic anthropology are the main approaches used to estimate the postmortem interval. Within the last decade, research has been done to understand microorganisms and their association with human decomposition. These studies have identified that microorganisms are detected in a clock-like manner, which is significant in the sense that this knowledge could aid the criminal justice community as microorganisms are ubiquitous and could be used to estimate the PMI upon the completion of more studies to understand the succession of microorganisms. Microbial succession has and continues to be studied extensively during outdoor decomposition studies or in a controlled lab setting. This study will observe and characterize the eukaryotic and prokaryotic microorganisms present during indoor decomposition.
The goal of this project is to characterize the plasmids of human clinical isolates of Salmonella enterica serovars Heidelberg and Typhimurium. First, the plasmid replicon types for each isolate were detected using multiplex PCR. Currently, I am using PCR to identify the antimicrobial resistant genes present on the plasmids (if any) and observe the susceptibility of each isolate to different antimicrobials according to CLSI guidelines.
