The Assessment of Activity of Antiseptic Agents against Biofilm of Staphylococcus aureus Measured with the Use of Processed Microscopic Images.

Staphylococcal biofilms are major causative factors of non-healing wound infections. Their treatment algorithms recommend the use of locally applied antiseptic agents to counteract the spread of infection. The efficacy of antiseptics against biofilm is assessed in vitro by a set of standard quantitative and semi-quantitative methods. The development of software for image processing additionally allowed for the obtainment of quantitative data from microscopic images of biofilm dyed with propidium iodine and SYTO-9 reagents, differentiating dead cells from live ones. In this work, the method of assessment of the impact of antiseptic agents on staphylococcal biofilm in vitro, based on biofilms' processed images, was proposed and scrutinized with regard to clinically relevant antiseptics, polyhexanide, povidone-iodine and hypochlorite. The standard quantitative culturing method was applied to validate the obtained data from processed images. The results indicated significantly higher activity of polyhexanide and povidone-iodine than hypochlorite against staphylococcal biofilm. Taking into account the fact that in vitro results of the efficacy of antiseptic agents against staphylococcal biofilm are frequently applied to back up their use in hospitals and ambulatory units, our work should be considered an important tool; providing reliable, quantitative data in this regard.

Pitfalls in evidence assessment: the case of chlorhexidine and alcohol in skin antisepsis.

Chlorhexidine has attracted increasing attention for its role in skin antisepsis in recent years. It was tested in several prominent clinical trials and subsequently recommended in important guidelines for blood culture collection, vascular catheter insertion and surgical skin preparation. We noticed and subsequently reported a widespread misinterpretation of evidence surrounding chlorhexidine and its role in skin antisepsis. Multiple clinical trial reports and systematic reviews that had assessed the clinical efficacy of chlorhexidine/alcohol combinations for skin antisepsis had attributed efficacy solely to the chlorhexidine component. This misinterpretation was carried over into the tertiary literature, including evidence-based guidelines. Here we discuss some of the scientific, ethical, patient safety and infection control implications of this misinterpretation, as well as broader implications for evidence-based medicine.

Assessment of povidone-iodine disinfectant compatibility with antimicrobial incise drape and adhesion inhibition on the skin using a gas chromatography/mass spectrometry approach.

According to orthopedists' reports, substitution of the original for a generic povidone-iodine (PVP-I) disinfectant could have led to some adhesion problems of antimicrobial incise drapes on the field of operation with the consequence of increasing the infection risk. Three methods have been used to assess the case: (a) a gas chromatography/mass spectrometry (GC-MS) approach quantifying methimazole formation from carbimazole, (b) in vitro adhesion experiments on a smooth glass plate surface and (c) the analysis of intrasurgical procedures. GC-MS results confirmed the higher potency of the original compared to the generic PVP-I. In vitro comparison of the adhesion on a PVP-I-pretreated glass surface showed no difference between the disinfectants and no significant destruction of the adhesive layer. However, due to different surgery preparation procedures, the remaining free skin surface granting sufficient adhesion differed if the intervening surgeon himself or his assistant prepared the field of operation. As a conclusion, the original PVP-I disinfectant is confirmed as the first-choice disinfectant for the field of operation. Adhesion problems were arising with new surgical staff and thus different preparation procedures. Exchanging PVP-I disinfectants cannot explain the adhesion problems of drapes and antimicrobial incise foils on the skin.

Experimental dermatophyte infection abated by povidone-iodine: assessment by computerized-assisted corneofungimetry.

The effect of antiseptics upon fungal growth inside human stratum corneum is poorly documented. Therefore the present study was undertaken to assess the anti-dermatophyte activity of a diluted povidone-iodine wash solution using the corneofungimetry bioassay. When compared to a non-medicated cleansing product, regular applications of the antimicrobial for two weeks significantly abated the fungal invasiveness inside human stratum corneum. The present findings are most likely relevant for the clinical practice.

Tumoricidal activity of antiseptics with assessment of cell viability in mice with severe combined immunodeficiency.

Previously, we have assessed the efficacy of different cytotoxic agents on the viability of SW620 human colonic carcinoma cells in vitro. In this study, we have investigated the tumoricidal efficacy of some antiseptic agents on SW620 human colonic carcinoma cells which were subsequently inoculated into severe combined immunodeficient (SCID) mice. An inoculum of 5 x 10(6) cells suspended in 200 microliters buffer solution was found to be the minimum number of cells needed to result in tumour growth within 8 weeks after subcutaneous injection into SCID mice. The integrity of the cells was assessed in vitro with the trypan blue exclusion test after 30 min incubation in distilled water (DW), chloramine 0.5% in DW and polyvinyl pyrrolidone iodine (PVP-I) 0.01, 0.05, 0.1 and 5% in DW. DW and PVP-I 0.01% were not tumoricidal, neither in vitro nor in vivo. In contrast, PVP-I 5% and chloramine 0.5% 'killed' all or almost all tumour cells in vitro and prevented their growth in vivo. PVP-I 0.05 and 0.1% were less effective in vitro than 5%, but could prevent in vivo proliferation unless an adjustment of the residual number of viable tumour cells was performed. These data indicate the importance of the amount of the tumour inoculum and hence the need to use a maximally effective 'killing' agent.

A test for the assessment of 'hygienic' hand disinfection using rotavirus.

A standardized test procedure is described in which finger tips are inoculated with bovine rotavirus. The level of virus recovered after disinfection of artificially contaminated hands with various disinfectant detergents, alcoholic solutions and alcoholic formulations was determined. The method was found to be easy to perform and reproducible. The most efficient method for removal of virus from fingertips was found to be treatment with alcoholic solutions or products. Soap and water and disinfectant detergents were found to be a much less effective method of removing virus from contaminated hands.