Biomedical subjects

Mark Pasmore

Publications and source records attributed to Mark Pasmore.

7 recordsLinked to original sources

PubMed2006

Biofilm formation on clinically noninfected penile prostheses.

PURPOSE: Biofilms are matrix enclosed bacterial populations that adhere to each other and/or to surfaces of implanted medical devices. Biofilm formation has consistently been demonstrated in association with infected penile prosthetic material. Clinically noninfected patients undergoing revision for mechanical malfunction have a surprisingly high rate of positive intraoperative cultures. After revision replacement prostheses have a higher rate of postoperative infection than first time implants. We characterized biofilm formation on penile prostheses in clinically noninfected patients undergoing revision surgery. MATERIALS AND METHODS: Ten patients undergoing revision or removal of inflatable penile prosthetic devices due to mechanical malfunction were included. Specimens from the corporeal cylinders, scrotal pump and reservoir were analyzed. Bacterial biofilm coverage was detected and characterized using confocal scanning laser microscopy. RESULTS: Bacterial biofilm formation associated with multiple microorganisms was demonstrated on 8 of 10 prostheses. Biofilms consisted of gram-positive rods, cocci and fungal elements. CONCLUSIONS: The degree of biofilm formation on these prosthetic devices suggests that most patients have bacterial coverage on the implant. Host mechanisms to control infection may lead to a homeostatic balance that enables biofilms to exist on the surface of the prosthesis without generating clinical infection. A critical threshold of biofilm extent may exist beyond which clinical infection may occur. These results justify further evaluation of biofilms and penile prosthesis infections. Furthermore, the findings help to explain why strategies such as mini salvage procedures to eliminate subclinical biofilms may decrease the postoperative infection risk in patients undergoing repair or replacement of penile prostheses.

Biofilms↗

PubMed2006

Bacterial biofilm inhibitors from Diospyros dendo.

One new (1) and four known (2-5) ursene triterpenes with potent inhibition of the formation of the bacterial biofilm Pseudomonas aeruginosa PA01 were obtained from Diospyros dendo using a high-throughput natural products chemistry procedure. These compounds were isolated as mass-limited samples. The miniaturization of the structure elucidation and dereplication was performed primarily utilizing a capillary-scale NMR probe.

Biofilms↗

PubMed2005

A new procedure allowing the complete removal and prevention of hemodialysis biofilms.

Most currently used disinfectants for dialysis machines have a good bactericidal efficacy on biofilms but leave dead cells on the surface. This contributes to the regrowth of biofilm and the release of pyrogens. A new anti-biofilm procedure consisting of sequential treatment combining enzymes and detergents is able to detach adherent cells. The efficacy of this procedure was assessed both in vitro and in reality. For in vitro studies, a biofilm model was set up. Studies were also performed in reality in a clinically used dialysis machine. Biofilm removal was first monitored by image analysis. Then, the biomass was detached by scraping and quantified by plate counts and endotoxin level measurement. Treated samples were compared to untreated control samples. The procedure led to the complete detachment of the biomass, both in vitro and in the reality situation. The aim of this procedure is to replace or complete the usual disinfection methods for medical devices.

Bacterial Adhesion↗

PubMed2005

A microbiological and confocal microscopy study documenting a slime-producing Staphylococcus epidermidis isolated from a nylon corneal suture of a patient with antibiotic-resistant endophthalmitis.

BACKGROUND: We describe a case of posttraumatic endophthalmitis unresponsive to systemic (amoxicillin+clavulanic acid and piperacillin/tazobactam), intra-ocular (vancomycin) and topical (ofloxacin, tetracycline and sulfametoxazole) antibiotic therapy. Microbiological and confocal microscopy studies of a nylon corneal suture revealed the presence of a slime-producing strain of Staphylococcus epidermidis. METHODS: We describe the history and clinical presentation of a 77-year-old man in whom a high-grade posttraumatic endophthalmitis resolved only after the removal of a single nylon corneal suture. Microbiological investigations of the aqueous, vitreous and suture were performed, and the propensity of the suture-associated isolate to form biofilm was assessed using confocal microscopy. RESULTS: A single stain of S. epidermidis was isolated from both aqueous and vitreous specimens and from the suture. The planktonic form of the isolate was susceptible in vitro to the antibiotics administered to the patient, but the strain was capable of forming biofilms and this phenotype showed resistance to high concentrations of the same antibiotics. CONCLUSIONS: The presence of a slime-producing strain of S. epidermidis should be considered in endophthalmitis that is unresponsive to specific antibiotic therapy, especially in cases in which an intra-ocular foreign body (e.g., a suture) is present.

Aged↗

PubMed2005

Endotoxin level measurement in hemodialysis biofilm using "the whole blood assay".

Biofilms have been found on the inner surface of silicone tubing inside dialysis machines. Endotoxin releasing from those biofilms increases the bioincompatibility of dialysis liquids and leads to long-term inflammatory complications among dialysis patients. Endotoxin measurement is recommended for the control of dialysis liquids. This article describes the use of a new method, the Whole Blood Assay (WBA), for endotoxin quantification in dialysis biofilms. Biofilms were suspended in sterile water by scraping the tubing samples. Diluted blood samples from healthy donors were stimulated overnight with the contaminated suspension. Stimulated mononuclear cells released IL-1beta in response to endotoxins. IL-1beta level was then measured using an ultrasensitive ELISA method. We demonstrated a semilogarithmic model in which the optical densities measured after the ELISA assay increases linearly with the levels of endotoxin. This model allowed the determination of the amount of endotoxins in biofilm samples with a detection limit of 0.032 EU/mL. Most of the time, the amounts of endotoxin measured by the WBA were higher than those measured by the Limulus Amoebocyte Lysate (LAL) assay. This study suggested the presence of "endotoxin-like" compounds different from the lipopolysaccharides that are not detected by the LAL assay. We concluded that the LAL is necessary but insufficient to have a representative quantification of endotoxins that could be hazardous to patient health.

Biofilms↗

PubMed2003

Biofilms, bacterial signaling, and their ties to marine biology.

Much of what is know about quorum sensing has come from the study of marine biology. The original description of the phenomenon was based on the study of marine bacteria and the luminescent pathway. More recently, aquatic organisms have been found to inhibit bacterial fouling of surfaces by blocking signaling pathways in the bacteria. These signaling effects have, over the last 5 years, been linked to biofilms. However, this correlation is not as straight forward as originally believed. Here, a brief overview of quorum sensing, and background on biofilms is provided, followed by a discussion of more recent work looking at the effects that environment may have on signal expression.

Bacteria↗

PubMed2003

The application of biofilm science to the study and control of chronic bacterial infections.

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.

Bacteria↗