MICROBIOLOGY AND IMMUNOLOGY

Monitoring Pathogenic Organisms in Water Systems Local to College Park, MD

Presenter: Jennifer German                                    Status: Faculty

Authors: Alli, Nazira A., Benzion, Hannah, Tran, Brian, Wu, Wei-lee, and German, Jennifer

 

Abstract: The Chesapeake Bay watershed is an important social and economic resource that covers approximately 64,000 square miles.  Monitoring local waterways within this area for various sources of pollution, including contamination by pathogenic organisms, is critical in ensuring the health and safety of this water system. The goal of this study is to develop a microbial profile of local waterways surrounding College Park, MD, in order to understand the extent of and source of microbial contamination.  PCR analysis of genomic material extracted from water samples using primers specific to fecal indicator bacteria have indicated bacterial contamination from a number of unique, specific animal species.  Additionally, primers against various pathogenic organisms have identified a number of species represented in these water samples. Antibiotic Resistance Assays have indicated these are not antibiotic resistant bacteria.  By establishing an accurate profile of the type and source of pathogenic organisms in the local water systems, efforts to clean up and control this contamination can be undertaken.

 

An Improved Method to Simultaneously Detect Salmonella enteritidis, Escherichia coli O157 and Listeria monocytogenes in FDA regulated Foods using Multiplex Real-time PCR

Presenter: Natalia Noroozi                           Status: Undergraduate Student

Authors: Venugopal Sathyamoorthy, Natalia Noroozi, Eunkyeong Park, Yunsoo Kim, Ben Tall, Yiping He, Seongeun Hwang, Larisa Trach, Hannah Chase, Barbara McCardell and Atin Datta

 

Abstract: Salmonella,  Escherichia coli O157, and Listeria monocytogenes are the most common foodborne pathogens. Identification of these pathogens individually can be done, however simultaneous detection of the three pathogens is more difficult and requires different techniques. Simultaneous detection of all three pathogens requires the Multiplex Real-Time PCR (qPCR). The objectiveof this project is to see what is the lowest colony forming units (CFUs) for each bacteria that can be detected using qPCR. Some foods are able to grow bacteria more easily, while others have inhibiting bacteria growth characteristics. Foods like onions, tomatoes, and cheese grow bacteria more easily. Spices, like black pepper and cinnamon grow bacteria more difficultly because they inhibit the growth of bacteria. The experimental procedures include manually adding the bacteria to the food samples (spiking), incubating the food samples, extracting the DNA and then running them through a qPCR machine which will test for the presence of these bacteria. When doing a qPCR test, four targets need to be detected: Salmonella, E. coli, Listeria, and an internal positive control (IAC). Real-time PCR is able to detect the presence of all four targets, if the experiment is set up appropriately. 

 

Disruption of Cyclic di-GMP Signaling by Small Molecules to Inhibit Alginate Production by Pseudomonas aeruginosa

Presenter: Eric Zhou                         Status: Undergraduate Student

Authors: Eric Zhou and Vincent T. Lee

 

Abstract: Pseudomonas aeruginosa is an opportunistic pathogen that affects over 90 percent of individuals with the genetic disorder cystic fibrosis (CF). Individuals with CF carry a mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which leads to the accumulation dehydrated mucus within the airways. As a result of dehydrated mucus accumulation, cilia within the lungs are unable to expel inhaled microbes from the airways, thereby facilitating the growth of pathogens such as P. aeruginosa. As a consequence, many CF patients experience chronic lung infection from a single strain of P. aeruginosa that persists for the entirety of their lives. In a phenomenon known as mucoid conversion, P. aeruginosa strains that chronically infect the lung accumulate genetic mutations that deactivate their mucA gene, which causes the bacteria to secrete copious amounts of the alginate virulence factor, resulting in increased lung inflammation and eventual morbidity and mortality. Alginate biosynthesis by P. aeruginosa is regulated by the bacterial signaling molecule cyclic di-GMP (c-di-GMP), which binds to the receptor protein Alg44 in order to activate alginate production. The identification of small molecules that disrupt the binding of Alg44 to c-di-GMP could subsequently inhibit the ability of P. aeruginosa to produce alginate. Here, we demonstrate the identification of a class of small molecules derived from benzo-triazolo-quinazolinone that inhibit the binding of Alg44 to c-di-GMP, and we show their in vivo efficacy in reducing alginate secretion by P. aeruginosa. The discovery of a class of inhibitors of Alg44 binding to c-di-GMP represents a novel area of study that could lead to the development of pharmaceuticals that reduce alginate production by P. aeruginosa, enabling CF patients to live healthier lives.

 

Neisseria gonorrhoeae from different anatomical locations in the same patient exhibits different MICs

 

Presenter: Lena Warrak                               Status: Undergraduate Student

Authors: FIRE AR Stream

 

Abstract: Neisseria gonorrhoeae (GC), responsible for the sexually transmitted infection gonorrhea, can infect the reproductive tract of women, and if left untreated, can lead to pelvic inflammatory disease (PID), infertility, and increase the risk of ectopic pregnancy. It can also lead to disseminated gonococcal infection and gonococcal arthritis. The CDC estimates that GC infections cause at least 24,000 women in the US to become infertile each year, with the estimated cost of diagnosis and treatment exceeding $5 billion per year. This is likely to underestimate the true cost of disease.  Gonorrhea is currently treated with antibiotics.   However, the recent emergence of antibiotic-resistant GC raises new concerns for controlling its infection, because once widely-recommended first-line antibiotics for gonorrhea are losing effectiveness around the world. While numerous studies have examined the mechanisms of antibiotic resistance of GC, there are few reports studying how, under physiological conditions and in different infection sites, antibiotic resistance contributes to the fitness of bacterium. We hypothesize that GC have different effective minimum inhibitory concentrations (MICs) in different infection sites.   To address this hypothesis, The FIRE AR stream examined the MICs of GC strains which were obtained from different anatomical locations. Our results identified significant differences in MIC among GC isolates from different sites in the same patient. This suggests that the human body imparts selective pressure and plays a role in the effectiveness of antibiotic treatment in GC infections. This stream seeks to understand the underlying genetic mechanisms associated with this observation.