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Biomedical subjects

G Pulverer

Publications and source records attributed to G Pulverer.

At least 19 recordsLinked to original sources
PubMed2003

Human cervicofacial actinomycoses: microbiological data for 1997 cases.

Actinomycoses are sporadically occurring endogenous polymicrobial inflammatory processes, in which fermentative actinomycetes of the genera Actinomyces, Propionibacterium, or Bifidobacterium act as the principal pathogens. Difficulties in diagnosing the disease in a timely and reliable fashion have led clinicians and microbiologists to grossly underestimate its medical importance. Therefore, we evaluated microbiological and selected clinical data derived from 1997 culture-positive cases of human cervicofacial actinomycoses examined in our laboratories during 1972-1999. The causative actinomycetes belonged to at least 9 different species, among which Actinomyces israelii and Actinomyces gerencseriae predominated. The well-known predisposition of male patients to acquire the disease varied with age and appeared to be especially pronounced in patients aged 20-60 years, the highest incidence being found in female patients aged 11-40 years and in male patients aged 21-50 years. The relevant procedures necessary for diagnosing human actinomycoses reliably, as well as details of their complex etiology, are discussed.

Actinobacteria↗
PubMed2001

Novel strategies to prevent catheter-associated infections in oncology patients.

Aggressive cytotoxic treatment of cancer contributes to the growing number of life-threatening infections. Vascular catheters create predominant risks for staphylococcal, enterococcal and candida blood stream infections. Although the contaminating microorganisms may be few in number, the altered host immune response in the presence of such implants as well as disease-associated immunosuppression implies that even small bacterial counts have to be regarded as highly virulent species. Diagnosis of catheter-related infection (CRI) remains difficult before withdrawal of the suspected catheter. Positive culture of catheter surface, lumen and hub and positive peripheral blood probes (paired quantitative blood culture) are predictive for catheter related bacteremia (CRB). Diligent catheter care and effective antimicrobial catheters may reduce prolonged hospital stay, increased morbidity or mortality and serious economical consequences. The most promising approach features the incorporation of antimicrobial drugs into the polymer matrices that entrap but do not bind the drugs, allowing for extended release. For the efficacious prevention of colonization in the microenvironment of the implantable device the concentration of the antimicrobial substances must exceed usual antibiotic concentrations by a thousand-fold. This is the desired effect--high concentration near the device surface and very low systemic concentration. Incorporation of antimicrobials in the bulk material that constitutes a device can be effective as shown in several in vitro and in vivo studies. In the future, modification of both short-term and long-term catheters by biofilm-active antimicrobials creating slow delivery systems may provide an effective method to protect patients from nosocomial infection in oncology.

Anti-Infective Agents↗
PubMed2000

[Prevention of infection with Streptococcus pneumoniae].

Streptococcus pneumoniae is the most common etiologic agent in outpatients pneumonia. Pneumococcal infections are often associated with high mortality risk in immunocompromised patients. An increasing resistance of Streptococcus pneumoniae to antibiotics is observed worldwide. This led to the official recommendation by the STIKO to use the vaccination in special risk groups. The commercially available 23-valent polysaccharide vaccine produces a reliable immune response against pneumococcal infection in children aged over 2 years and adults. The recommendation should be more realized in practice.

Adolescent↗
PubMed2000

Measurement of ultrasonic-induced chlorhexidine liberation: correlation of the activity of chlorhexidine-silver-sulfadiazine-impregnated catheters to agar roll technique and broth culture.

The diagnosis of intravascular catheter-related infections continues to be a challenge to both the clinician and the microbiologist. To assess the antiseptic effects of silver-sulfadiazine-chlorhexidine-impregnated central venous catheters (SSC) on catheter culture systems, segments of fresh antiseptic- and non antiseptic-impregnated catheters as well as extracted catheters following five days of immersion in PBS were sonicated. The chlorhexidine liberated from the catheter material by ultrasonication was measured by HPLC. Fresh antiseptic-impregnated catheter segments rolled on seeded agar plates produced inhibition zones unlike catheters which had been extracted for >five days in phosphate buffered saline (PBS). Scanning electron microscopy (SEM) revealed that chlorhexidine-silversulfadiazine crystals were located in the superficial catheter matrix. Direct contact of superficially located drug particles with seeded agar plates probably caused the inhibition of bacterial growth. The study suggests that antiseptic compounds readily elute from fresh catheters during solid medium-based culturing processes and ultrasonication. The addition of inhibitors of silversulfadiazine-chlorhexidine to media may be prudent especially when culturing antimicrobial loaded catheters removed after short inwelling times.

Anti-Infective Agents, Local↗
PubMed2000

The antimicrobial efficacy of a new central venous catheter with long-term broad-spectrum activity.

Indwelling vascular catheters are a major cause of nosocomial sepsis. Prevention of colonization of polymeric surfaces by continuous release of bactericidal, highly biocompatible antimicrobials incorporated into polymers has been investigated as a promising new approach. An antimicrobial polyurethane catheter was investigated by HPLC and various antimicrobial assays. Controlled drug delivery governed by the physico-chemical mass transfer from the polyurethane bulk provided long-term release of the antimicrobial substances from the material to the outer surface and catheter lumen. The in vitro activity of catheters coated with miconazole and rifampicin against 158 clinical isolates of catheter-associated infections was evaluated. Incubated in physiological NaCl at 37 degrees C, the half-life of inhibitory activity of catheters coated with miconazole or rifampicin exceeded 3 weeks. In static and dynamic adhesion assays, coated catheters were able to prevent colonization with Staphylococcus aureus, Staphylococcus epidermidis and enterococci. To produce catheters resistant to infection, a potent antimicrobial efficacy combined with an excellent biocompatibility over time is needed. The long lasting efficacy of the antimicrobial polyurethane alloy as well as the increased antifungal activity of miconazole combined with rifampicin may be regarded as a promising improvement for long-term central venous access.

Anti-Bacterial Agents↗
PubMed2000

"Difficult to treat infections" pharmacokinetic and pharmacodynamic factors--a review.

"Difficult to cure infections" are characterized by poor penetration of antibiotics into infected vegetations, altered metabolic state of bacteria within the vegetation, absence of adequate host defense/cellular response. These infections typically include endocarditis, urinary tract infections (infected urinary tract stones), abscesses, infected fibrin clots (septic thromboemboli, haematomas, catheter-related infections) and foreign body infections. Four main aspects are discussed for the influence on human therapy: 1. the kinetics of antibiotic diffusion into vegetations 2. the specificity of some pharmacodynamic aspects and pharmacokinetic regimes 3. fibrin as one of the main constituents associated with infectious processes and 4. synergistical activities of antibiotic combinations on bacterial vegetations.

Anti-Bacterial Agents↗
PubMed1999

Antimicrobial substances and effects on sessile bacteria.

Biofilms occur in natural aquatic ecosystems and on surfaces of biomaterials. They are generally associated with clinical infections predominantly of prosthetic hip joints, heart valves and catheters. Sessile microorganisms may be intimately associated with each other and to solid substratum through binding to and inclusion into exopolymer matrices on biofilms. The establishment of functional colonies within the exopolymeric matrices generate physico-chemical gradients within biofilms, that modify the metabolism and cell-wall properties of the microorganism. A consequence of biofilm growth is an enhanced microbial resistance to chemical antimicrobial agents and antibiotics. Investigations on the antimicrobial efficacy of antibiotics, antiseptics and antimicrobial heavy ions, however, gave controversial results. No single antimicrobial substance has been developed for the efficient eradication of adherent bacteria. This review elucidates the mechanisms of microbial resistance in biofilms and strategies for the prevention of biofilm development. Pharmacokinetical and pharmacodynamical issues for the screening of biofilm-active drugs are presented. Combinations of antistaphylococcal antibiotics with rifampin may be advantageous for preventing and curing biomaterial infections.

Anti-Bacterial Agents↗
PubMed1998

Investigation of a rifampin, fusidic-acid and mupirocin releasing silicone catheter.

After strict hygienical measures have been exhausted the use of plastic materials with antibacterial activity may reduce catheter related-bacterial colonization. An antimicrobial silicone catheter was investigated by HPLC-measurement, SEM, antimicrobial assays and standard biocompatibility tests. The modified catheter was highly biocompatible and the antimicrobial leaching non-toxic. The initially release rate was governed by the drug solubility in the 'sink' and surface loading ('burst effect'). The second continuous period depended on the drug velocity in the silicone matrix and was extended up to 100 days with a proportionality to square root of t for each drug. Diffusion exponents were in range of 2 x 10(-8) to 1 x 10(-9) (cm2 sec(-1)). The lower diffusion exponent of mupirocin was explained by its higher cohesion energy and lower physico-chemical compatibility with the embedding silicone. The antimicrobial drugs were in a molecular-dispersed state with the silicone-matrix, whereas superficially located crystals of the antibiotics covering the catheter surface could be demonstrated by SEM.

Anti-Bacterial Agents↗
PubMed1998

Efficacy of silver-coated medical devices.

Silver coating of medical devices is believed to prevent device-associated infection. Several in-vitro and in-vivo studies, as well as clinical observations on silver-nylon, silver-intramedullary pins, silver oxide Foley catheters and silver-coated vascular prostheses have been performed during the past 30 years. Nevertheless, randomized clinical studies showing efficacy of such coated medical devices in high-risk patient populations are rare, have dealt with very small numbers of patients or are controversial. Physico-chemical, pharmacological and microbiological data explaining the antimicrobial efficacy of silver in prophylaxis of implants are presented here, as well as the scientific background for the established clinical benefits of silver-preparations in burns.

Blood Vessel Prosthesis↗