Browsing by Author "Veeh, Richard Harold"

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The application of biofilm science to the study and control of bacterial infections
(2003-11) Costerton, J. William; Veeh, Richard Harold; Shirtliff, Mark E.; Pasmore, M.; Post, C.; Ehrlich, Garth D.
Unequivocal direct observations have established that the bacteria that cause device-related and other chronic infections grow in matrix-enclosed biofilms. The diagnostic and therapeutic strategies that have served us so well in the partial eradication of acute epidemic bacterial diseases have not yielded accurate data or favorable outcomes when applied to these biofilm diseases. We discuss the potential benefits of the application of the new methods and concepts developed by biofilm science and engineering to the clinical management of infectious diseases.
Biofilm-related infections of cerebrospinal fluid shunts
(2006-04) Fux, C. A.; Quigley, Mark; Worel, A. M.; Post, C.; Zimmerli, S.; Ehrlich, Garth D.; Veeh, Richard Harold
Cerebrospinal fluid (CSF) shunts carry a high risk of complications. Infections represent a major cause of shunt failure. Diagnosis and therapy of such infections are complicated by the formation of bacterial biofilms attached to shunt surfaces. This study correlated the pathophysiology and clinical course of biofilm infections with microscopic findings on the respective shunts. Surface irregularities, an important risk factor for shunt colonisation with bacteria, were found to increase over time because of silicone degradation. Scanning electron-microscopy (SEM) documented residual biological material (dead biofilm), which can further promote extant bacterial adhesion, on newly manufactured shunts. Clinical course, and SEM both documented bacterial dissemination against CSF flow and the monodirectional valve. In all cases, biofilms grew on both the inner and outer surfaces of the shunts. Microscopy and conventional culture detected all bacterial shunt infections. Analyses of 16S rDNA sequences using conserved primers identified bacteria in only one of three cases, probably because of previous formalin fixation of the samples.
Characterization of methyl tert-butyl ether-degrading bacteria from a gasoline-contaminated aquifer
(2002-01) Kern, Eric Anthony; Veeh, Richard Harold; Macur, Richard E.; Cunningham, Alfred B.
Molecular microbial community analysis was combined with traditional cultivation strategies to investigate the presence of methyl tert-butyl ether (MTBE)-degrading bacteria in a gasoline-contaminated aquifer (Ronan, MT). A bacterial consortium, RS24, which is capable of complete mineralization of MTBE as a sole carbon and energy source was enriched from soil and aquifer materials taken from the contaminated site. The consortium was capable of degrading MTBE at rates up to 0.66 mg d-,1 with corresponding gross biomass yields of 0.25 ± 0.02 mg dry biomass (mg MTBE)-1. Two MTBE-degrading isolates identified as Pseudomonas Ant9 and Rhodococcus koreensis were obtained from the consortium. However, both isolates required the presence of 2-propanol as a cosubstrate for MTBE degradation. Denaturing gradient gel electrophoresis (DGGE) of Polymerase Chain Reaction (PCR)-amplified 16S rDNA confirmed the presence of both isolates in the initial consortium and indicated their disappearance with transfer and subculturing. MTBE degradation and cell growth by the consortium was stimulated by the presence of spent culture medium, suggesting the production of a growth factor during MTBE degradation. These results indicate the presence of naturally occurring MTBE-degrading bacteria in a contaminated aquifer and suggest the potential for natural attenuation or enhanced aerobic oxidation.
Detection of staphylococcus aureus biofilm on tampons and menses components
(2003-08) Veeh, Richard Harold; Shirtliff, Mark E.; Petik, Jill R.; Flood, Janine A.; Davis, Catherine C.; Seymour, Jon L.; Hansmann, Melanie A.; Kerr, Kathy M.; Pasmore, M.; Costerton, J. William
Culturing has detected vaginal Staphylococcus aureus in 10%–20% of women. Because growth mode can affect virulence expression, this study examined S. aureus–biofilm occurrence in 44 paired—tampon and vaginal-wash—specimens from 18 prescreened women, using fluorescent in situ hybridization (FISH). All 44 specimens were also analyzed for S. aureus by standard culturing on mannitol salt agar, which produced positive results for 15 of the 44 specimens. FISH detected S. aureus cells in all 44 specimens, and S. aureus biofilm was observed in 37 of the 44 specimens. Independent confirmation of the presence of S. aureus in specimens from all 18 women was also obtained by amplification, via polymerase chain reaction, of an S. aureus–specific nuclease gene. The results of this study demonstrate that S. aureusbiofilm can form on tampons and menses components in vivo. Additionally, the prevalence of vaginal S. aureus carriage may be more prevalent than what is currently demonstrated by standard culturing techniques
Fate of chlorsulfuron, 2, 4-D, and naphthalene in unsaturated soil
(Montana State University - Bozeman, College of Agriculture, 1993) Veeh, Richard Harold
The influence of selected soil physical properties, soil type and site characteristics, soil temperature, and soil moisture on the response of small grains to potassium on Montana soils
(Montana State University - Bozeman, College of Agriculture, 1981) Veeh, Richard Harold
Microbially influenced degradation of cement-solidified low-level radioactive waste forms
(1994) Rogers, Robert D.; Hamilton, W. A.; Veeh, Richard Harold; McConnell, J. W.
Because of its apparent structural integrity, cement has been widely used in the United States as a binder to solidify Class B and C low-level radioactive waste (LLW). However, the resulting cement preparations are susceptible to failure due to the actions of stress and environment. This paper contains information on three groups of microorganisms that are associated with the degradation of cement materials : sulfur-oxidizing bacteria (Thiobacillus), nitrifying bacteria (Nitrosomonas and Nitrobacter), and heterotrophic bacteria, which produce organic acids. Preliminary work using laboratory- and vendor-manufactured, simulated waste forms exposed to thiobacilli has shown that microbiologically influenced degradation has the potential to severely compromise the structural integrity of ion-exchange resin and evaporator-bottoms waste that is solidified with cement. In addition, it was found that a significant percentage of calcium was leached from the treated waste forms. Also, the surface pH of the treated specimens was decreased to below 2. These conditions apparently contributed to the physical deterioration of simulated waste forms after 30 to 60 days of exposure.
Monitoring of microbial souring in chemically treated, produced-water biofilm systems using molecular techniques
(2005-04) Kjellerup, B. V.; Veeh, Richard Harold; Sumithrarathne, P.; Thomsen, T. R.; Buckingham-Meyer, Kelli; Frolund, B.; Sturman, Paul J.
The identification of bacteria in oil production facilities has previously been based on culture techniques. However, cultivation of bacteria from these often-extreme environments can lead to errors in identifying the microbial community members. In this study, molecular techniques including fluorescence in situ hybridization, PCR, denaturing gradient gel electrophoresis, and sequencing were used to track changes in bacterial biofilm populations treated with nitrate, nitrite, or nitrate+molybdate as agents for the control of sulfide production. Results indicated that nitrite and nitrate+molybdate reduced sulfide production, while nitrate alone had no effect on sulfide generation. No long-term effect on sulfide production was observed. Initial sulfate-reducing bacterial numbers were not influenced by the chemical treatments, although a significant increase in sulfate-reducing bacteria was observed after termination of the treatments. Molecular analysis showed a diverse bacterial population, but no major shifts in the population due to treatment effects were observed.
Mucosal biofilm formation on middle-ear mucosa in a nonhuman primate model of chronic suppurative otitis media
(2005-08) Dohar, Joseph E.; Hebda, Patricia A.; Veeh, Richard Harold; Awad, Marie; Costerton, J. William; Hayes, J. T.; Ehrlich, Garth D.
Background: An increased awareness of bacterial biofilms and their formation has led to a better understanding of bacterial infections that occur in the middle ear. Perhaps the best studied pathogen for its propensity toward biofilm formation is Pseudomonas aeruginosa, also the primary pathogen in chronic suppurative otitis media (CSOM). Objective: The aim of this study was to determine whether P. aeruginosa forms a biofilm in the middle ear in the setting of CSOM in a nonhuman primate model. Methods: Cynomolgus monkeys underwent perforation of the tympanic membrane and inoculation of the middle ear with a known biofilm-forming strain of P. aeruginosa. The contralateral ear was used as an internal control and was neither perforated nor infected. At the end of the study period, both ears were irrigated to remove planktonic bacteria, and the middle ear mucosa was removed and examined ultrastructurally using scanning electron microscopy (SEM) for determination of the presence or absence of biofilm formation. Main Outcome Measure: The identification of middle ear biofilm containing rod-shaped bacteria. Results: SEM revealed that P. aeruginosa formed bacterial biofilm in vivo on the middle ear mucosal surface, seen only in the infected ear. Interestingly, biofilm formation caused by cocci was also seen in both the experimental as well as the control ear. Conclusion: P. aeruginosa forms biofilms in the middle ear in CSOM in primates. To our knowledge, this is the first report of disease-associated bacterial biofilm in a nonhuman primate model of CSOM. Such a model lays a foundation for much needed study into the role of biofilms in the pathophysiology of CSOM. Should CSOM be caused by biofilms, which is uncertain at this time, development of novel strategies for treatment and prevention may be possible. The finding of both rods and cocci forming biofilms also warrants further investigation.
Mucosal biofilm formation on middle-ear mucosa in the chinchilla model of otitis media
(2002-04) Ehrlich, Garth D.; Veeh, Richard Harold; Wang, Xue; Costerton, J. William; Hayes, Jay D.; Hu, Fen Z.; Daigle, Bernie J.; Ehrlich, Miles D.; Post, J. C.
CONTEXT Chronic otitis media with effusion (OME) has long been considered to be a sterile inflammatory process. The previous application of molecular diagnostic technologies to OME suggests that viable bacteria are present in complex communities known as mucosal biofilms; however, direct imaging evidence of mucosal biofilms associated with OM is lacking. OBJECTIVE. To determine whether biofilm formation occurs in middle-ear mucosa in an experimental model of otitis media. DESIGN and MATERIALS. A total of 48 research-grade, young adult chinchillas weighing 500g were used for 2 series of animal experiments: one to obtain specimens for scanning electron microscopy and the other to obtain specimens for confocal laser scanning microscopy using vital dyes. In each series, 21 animals were bilaterally injected with viable Haemophilus influenzae bacteria and 1 was inoculated to account for expected mortality. Three served as negative controls. Effusions and mucosal specimens were collected from 2 infected animals that were euthanized at 3, 6, 12, and 24 hours and at days 2, 4, 5, 10, 16, and 22 after inoculation. MAIN OUTCOME MEASURES. Images were analyzed for biofilm morphology, including presence of microcolony formation and for presence of bacteria on tissue surfaces. RESULTS. Scanning electron microscopy demonstrated that biofilm formation was evident in all specimens from animals beginning 1 day after infection and was present through 21 days. Confocal laser scanning microscopy indicated that bacteria within the biofilms was viable. CONCLUSION. These preliminary findings provide evidence that mucosal biofilms form in an experimental model of otitis media and suggest that biofilm formation may be an important factor in the pathogenesis of chronic otitis media with effusion.
Nanoscale Structural and Mechanical Properties of Nontypeable Haemophilus influenzae Biofilms
(2009-02) Arce, Fernando Teran; Carlson, Ross P.; Monds, James; Veeh, Richard Harold; Hu, Fen Z.; Stewart, Philip S.; Lal, Ratnesh; Ehrlich, Garth D.; Avci, Recep
Nontypeable Haemophilus influenzae (NTHI) bacteria are commensals in the human nasopharynx, as well as pathogens associated with a spectrum of acute and chronic infections. Two important factors that influence NTHI pathogenicity are their ability to adhere to human tissue and their ability to form biofilms. Extracellular polymeric substances (EPS) and bacterial appendages such as pili critically influence cell adhesion and intercellular cohesion during biofilm formation. Structural components in the outer cell membrane, such as lipopolysaccharides, also play a fundamental role in infection of the host organism. In spite of their importance, these pathogenic factors are not yet well characterized at the nanoscale. Here, atomic force microscopy (AFM) was used in aqueous environments to visualize structural details, including probable Hif-type pili, of live NTHI bacteria at the early stages of biofilm formation. Using single-molecule AFM-based spectroscopy, the molecular elasticities of lipooligosaccharides present on NTHI cell surfaces were analyzed and compared between two strains (PittEE and PittGG) with very different pathogenicity profiles. Furthermore, the stiffness of single cells of both strains was measured and subsequently their turgor pressure was estimated.
Prevalence of microbial biofilms on selected fresh produce and household surfaces
(2004-08) Rayner, Joanna; Veeh, Richard Harold; Flood, Janice Elizabeth Desi
Investigations of biofilms in domestic environments are sparsely represented in the literature. In this study, samples of various household surfaces, including food, laundry and kitchen items, were analyzed for evidence of biofilm presence. Visualization of the surfaces was carried out using cryostage scanning electron microscopy (CSEM) and light microscopy. Qualitative evidence of the presence of biofilm formation was obtained from all of the sample groups analyzed, suggesting the widespread existence of microorganisms in biofilms on domestic surfaces. This suggests that biofilms may be important in household hygiene, and highlights the need for standardized, approved biofilm methods suitable for consumer products testing.
Soil depth and temperature effects on microbial degradation of 2,4-d
(1996) Veeh, Richard Harold; Inskeep, William P.; Camper, Anne K.
Numerous soil factors and climatic conditions affect the degradation rate of pesticides in soils. A major soil factor influencing herbicide degradation is the composition and abundance of the microbiota, which has been shown to vary considerably with soil depth. Another important variable affecting microbial growth and degradation kinetics is temperature. Soil samples from 0- to 30-, 30- to 60-, and 60- to 120-cm depths of two Montana soils were placed in reaction flasks and treated with 14C-labeled 2,4-D at representative field use rates at temperatures of 10, 17, and 24°C. A carrier gas was used to continuously evacuate evolved 14CO2 into NaOH traps as a measure of 2,4-D degradation. Comparisons of the effects of soil depth and temperature were made by fitting experimental data to both first-order and logistic kinetic models. Degradation rates of 2,4-D decreased significantly with increasing soil depth and were positively correlated with bacterial plate counts. Effects of temperature on degradation rate constants were adequately described using the Arrhenius equation. Degradation rates of 2,4-D and bacterial enumerations were positively correlated with changes in soil organic C as a function of soil depth. These results support the idea that changes in organic C with soil depth could be used as a parameter for estimating changes in degradation rate as a function of soil depth. Efforts to model the transport of 2,4-D in soils should account for variation in degradation rate as a function of soil depth and temperature.