Bacteria Commons^™

Microbicidal Effects Of Α- And Θ-Defensins Against Antibiotic-Resistant Staphylococcus Aureus And Pseudomonas Aeruginosa, Kenneth P. Tai, Karishma Kamdar, Jason Yamaki, Valerie V. Le, Dat Tran, Patti Tran, Michael E. Selsted, Andre J. Ouelette, Annie Wong-Beringer

Pharmacy Faculty Articles and Research

Antibiotic-resistant bacterial pathogens threaten public health. Because many antibiotics target specific bacterial enzymes or reactions, corresponding genes may mutate under selection and lead to antibiotic resistance. Accordingly, antimicrobials that selectively target overall microbial cell integrity may offer alternative approaches to therapeutic design. Naturally occurring mammalian α- and θ-defensins are potent, non-toxic microbicides that may be useful for treating infections by antibiotic-resistant pathogens because certain defensin peptides disrupt bacterial, but not mammalian, cell membranes. To test this concept, clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), including vancomycin heteroresistant strains, and ciprofloxacin-resistant Pseudomonas aeruginosa (Cip^R-PA) were tested for sensitivity to …

Modeling Fecal Bacteria In Oregon Coastal Streams Using Spatially Explicit Watershed Characteristics, Paul Bryce Pettus

Dissertations and Theses

Pathogens, such as Escherichia coli and fecal coliforms, are causing the majority of water quality impairments in U.S., making up ~87% of this grouping's violations. Predicting and characterizing source, transport processes, and microbial survival rates is extremely challenging, due to the dynamic nature of each of these components. This research built upon current analytical methods that are used as exploratory tools to predict pathogen indicator counts across regional scales. Using a series of non-parametric methodologies, with spatially explicit predictors, 6657 samples from non-estuarine lotic streams were analyzed to make generalized predictions of regional water quality. 532 frequently sampled sites in …

Regulation Of Hyaluronate Lyase (Hyla) Expression By Regr A Transcriptional Repressor In Streptococcus Pyogenes, Alexis A. Kordis

Biological Sciences Theses & Dissertations

Streptococcus pyogenes, group A streptococci (GAS), causes diseases ranging from asymptomatic to life threatening. Some strains of S. pyogenes produce extracellular hyaluronate lyase (HylA), a potential virulence factor. HylA is an enzyme that degrades hyaluronic acid, which is found in the extracellular matrix of human tissues. The breakdown of the host tissue contributes to the spread of infection. The hylA gene is not constitutively expressed in vitro, which implies regulation.

A proposed regulator of hyaluronate lyase expression is RegR, a LacI/GalR like protein. A vector containing disrupted regR was electro-transformed into S. pyogenes M-type 22 strain 10403. Growth characteristics …

Regulating Rsma Expression In Pseudomonas Aeruginosa, Sean D. Stacey

Electronic Theses and Dissertations

Pseudomonas aeruginosa, a Gram-negative bacillus, commonly infects immunocompromised individuals and uses a variety of virulence factors to persist in these hosts. The posttranscriptional regulator, RsmA, plays a role in the expression of many virulence factors in P. aeruginosa. RsmA up regulates virulence factors used in colonizing hosts. However, regulation of rsmA is not well elucidated. Transposon mutagenesis was performed on P. aeruginosa containing a transcriptional rsmA-lacZ fusion to answer this question. Mutants were screened via β-galactosidase assay and transposon insertions identified via arbitrary PCR. A probable MFS transporter, we named mtpX, was one significant transposon mutant identified. …

Tigecycline Induction Of Phenol-Soluble Modulins By Invasive Methicillin-Resistant Staphylococcus Aureus Strains, Jason Yamaki, Timothy Synold, Annie Wong-Beringer

Pharmacy Faculty Articles and Research

We examined the effects of tigecycline on three types of exoproteins, α-type phenol-soluble modulins (PSMα1 to PSMα4), α-hemolysin, and protein A, in 13 methicillin-resistant Staphylococcus aureus isolates compared to those of clindamycin and linezolid. Paradoxical increases in PSMαs occurred in 77% of the isolates with tigecycline at 1/4 and 1/8 MICs and clindamycin at 1/8 MIC compared to only 23% of the isolates with linezolid at 1/8 MIC. Induction was specific to PSMα₁ to PSMα₄, as protein A and α-hemolysin production was decreased under the same conditions by all of the antibiotics used.

Effects Of Clostridium Difficile On The Human Immune Response, Mike Mcgovern

Honors Projects in Science and Technology

Clostridium difficile is a bacterium that is rapidly becoming a large issue in the medical community due to its tendency to infect hospital patients and its resistance to antibiotics. By studying the way in which the pathogen interacts with the human immune system, it is possible to better understand how the body naturally fights off the disease. This knowledge can allow medical professionals to develop treatments that can help curtail the infection before serious symptoms occur. Working under a grant program alongside Professors Kirsten Hokeness and Chris Reid, I was able to research the effects that exposure to the C. …

A Guide To Enterotypes Across The Human Body: Meta- Analysis Of Microbial Community Structures In Human Microbiome Datasets, Omry Koren, Dan Knights, Antonio Gonzalez, Levi Waldron, Nicola Segata, Rob Knight, Curtis Huttenhower, Ruth E. Ley

Publications and Research

Recent analyses of human-associated bacterial diversity have categorized individuals into ‘enterotypes’ or clusters based on the abundances of key bacterial genera in the gut microbiota. There is a lack of consensus, however, on the analytical basis for enterotypes and on the interpretation of these results. We tested how the following factors influenced the detection of enterotypes: clustering methodology, distance metrics, OTU-picking approaches, sequencing depth, data type (whole genome shotgun (WGS) vs.16S rRNA gene sequence data), and 16S rRNA region. We included 16S rRNA gene sequences from the Human Microbiome Project (HMP) and from 16 additional studies and WGS sequences from …