Photodynamic inactivation of bacteria to decolonize meticillin-resistant Staphylococcus aureus from human skin.

BACKGROUND: To prevent infections that arise from the skin surface it is necessary to decolonize human skin prior to any proposed treatment or surgical intervention. Photodynamic inactivation of bacteria (PIB) uses cationic photosensitizers that attach to the surface of bacteria, generate reactive oxygen species on light irradiation and thereby kill bacteria via oxidative mechanisms. OBJECTIVES: To evaluate the potential and the safety of PIB for decolonization of bacteria from skin. METHODS: PIB with the new photosensitizer SAPYR [2-((4-pyridinyl)methyl)-1H-phenalen-1-one chloride] was initially tested against different bacterial species in vitro. Then, ex vivo porcine skin samples were used as a model for decolonization of different bacteria species. The numbers of viable bacteria were quantified and the mitochondrial activity of skin cells was histologically analysed (using nitroblue tetrazolium chloride, NBTC). The same procedure was performed for human skin and meticillin-resistant Staphylococcus aureus (MRSA). RESULTS: The in vitro studies showed a 5 log10 reduction of all tested bacterial species. On ex vivo porcine skin samples, PIB reduced the viability of all tested bacterial species by at least 3 log10 steps. On human skin samples ex vivo, PIB reduced the number of viable MRSA by maximal 4·4 log10 steps (1000 µmol L-1 SAPYR, incubation time 10 min, 60 J cm-2 ). NBTC staining showed normal mitochondrial activity in skin cells after all PIB modalities. CONCLUSIONS: The results of this study show that PIB can effectively and safely kill bacteria like MRSA on the skin surface and might have the potential of skin decolonization in vivo.

Photodynamic coatings kill bacteria on near-patient surfaces in intensive care units with low light intensities.

BACKGROUND: Surfaces in close proximity to patients within hospitals may cause healthcare-associated infections. These surfaces are repositories for pathogens facilitating their transmission among staff and patients. Regular cleaning and disinfection of these surfaces provides only a temporary elimination of pathogens with inevitable recontamination. Antimicrobial coatings (AMCs) of such surfaces may additionally reduce the risk of pathogen transmissions. AIM: To evaluate the efficacy of a standard and a novel photodynamic AMC, even at very low light intensities, in a field study conducted in two ICUs at our university hospital. METHODS: The microbial burden was determined on three coatings: standard photodynamic AMC (A), a novel photodynamic AMC (B), and an inactive AMC as control (C). The control coating C was identical to standard coating A, but it contained no photosensitizer. During a three-month period, 699 samples were collected from identical surfaces using eSwab and were analysed (cfu/cm2). FINDINGS: Mean values of all surfaces covered with control coating (C) showed a microbial burden of 5.5 ± 14.8 cfu/cm2. Photodynamic AMC showed significantly lower mean value of 1.6 ± 4.6 cfu/cm2 (coating A; P < 0.001) and 2.7 ± 9.6 (coating B; P < 0.001). When considering a benchmark of 2.5 cfu/cm2, the relative risk for higher microbial counts was reduced by 52% (coating A) or 40% (coating B), respectively. CONCLUSION: Both photodynamic AMCs offer a substantial, permanent risk reduction of microbial counts on near-patient surfaces in ICUs with low light intensities.

Retrospective genome-oriented analysis reveals low transmission rate of multidrug-resistant Pseudomonas aeruginosa from contaminated toilets at a bone marrow transplant unit.

BACKGROUND: Prevention of toilet-to-patient transmission of multidrug-resistant Pseudomonas aeruginosa (MDR PA) poses management-related challenges at many bone marrow transplant units (BMTUs). AIM: To conduct a longitudinal retrospective analysis of the toilet-to-patient transmission rate for MDR PA under existing infection control (IC) measures at a BMTU with persistent MDR PA toilet colonization. METHODS: The local IC bundle comprised: (1) patient education regarding IC; (2) routine patient screening; (3) toilet flushing volume of 9 L; (4) bromination of toilet water tanks, and (5) toilet decontamination using hydrogen peroxide. Toilet water was sampled periodically between 2016 and 2021 (minimum every three months: 26 intervals). Upon MDR PA detection, disinfection and re-sampling were repeated until ≤3 cfu/100 mL was reached. Whole-genome sequencing (WGS) was performed retrospectively on all available MDR PA isolates (90 out of 117 positive environmental samples, 10 out of 14 patients, including nine nosocomial). FINDINGS: WGS of patient isolates identified six sequence types (STs), with ST235/CT1352/FIM-1 and ST309/CT3049/no-carbapenemase being predominant (three isolates each). Environmental sampling consistently identified MDR PA ST235 (65.5% ST235/CT1352/FIM-1), showing low genetic diversity (difference of ≤29 alleles by core-genome multi-locus sequence typing (cgMLST)). This indicates that direct toilet-to-patient transmission was infrequent although MDR PA was widespread (detection on 79 occasions, detection in every toilet). Only three MDR PA patient isolates can be attributed to the ST235/CT1352/FIM-1 toilet MRD PA population over six years. CONCLUSION: Stringent targeted toilet disinfection can reduce the potential risk for MDR PA acquisition by patients.

[Practical problems with the use of topicals in geriatric dermatology]. / Praktische Aspekte bei der Anwendung von Topika in der geriatrischen Dermatologie.

Changes related to aging affect all layers of the skin and are influenced by both intrinsic conditions and extrinsic factors. The extent of the senescent changes can vary enormeously in seniors, so that an individual assessment is useful and often necessary. Of particular clinical importance are changes in the epidermis, which entail a complex reduction of the barrier function and a reduction in the compensatory capacity with regard to exogenous noxae. This results in increased susceptibility, especially toward infection and cancer. Against this background, a prophylactic strategy for the substitution of the physicochemical and thus also the microbiological barrier in the context of basic care is very important. In order to be able to implement these consistently, recommendations for preparations explicitly designed for aging skin as well as practical instructions for use are highly meaningful. The latter should take into account limitations regarding mobility as well as possible cognitive deficits of seniors. For this purpose, creams and suitable preparations in terms of viscosity and composition should be recommended. In order to facilitate implementation, written or pictorial recommendations for application as well as digital assistance systems can be used. Due to demographic developments in Germany and Europe, the clinical relevance of geriatric dermatology will significantly increase in the future.

Novel photodynamic coating reduces the bioburden on near-patient surfaces thereby reducing the risk for onward pathogen transmission: a field study in two hospitals.

BACKGROUND: Near-patient surfaces are recognized as a source for hospital-acquired infections. Such surfaces act as reservoirs for microbial contamination by which pathogens can be transmitted from colonized or infected patients to susceptible patients. Routine disinfection of surfaces only results in a temporal elimination of pathogens, and recontamination inevitably occurs shortly between disinfections. AIM: A novel antimicrobial coating based on photodynamics was tested under laboratory conditions and subsequently in a field study in two hospitals under real-life conditions. METHODS: Identical surfaces received a photodynamic or control coating. Bacterial counts [colony-forming units (cfu)/cm2) were assessed regularly for up to 6 months. FINDINGS: The laboratory study revealed a mean reduction of several human pathogens of up to 4.0 ± 0.3 log10. The field study in near-patient environments demonstrated mean bacterial values of 6.1 ± 24.7 cfu/cm2 on all control coatings. Photodynamic coatings showed a significantly lower mean value of 1.9 ± 2.8 cfu/cm2 (P<0.001). When considering benchmarks of 2.5 cfu/cm2 or 5 cfu/cm2, the relative risk for high bacterial counts on surfaces was reduced by 48% (odds ratio 0.38, P<0.001) or 67% (odds ratio 0.27, P<0.001), respectively. CONCLUSION: Photodynamic coatings provide a significant and lasting reduction of bacterial counts on near-patient surfaces, particularly for high bacterial loads, in addition to routine hygiene. The promising results of this proof-of-concept study highlight the need for further studies to determine how this novel technology is correlated with the frequency of hospital-acquired infections.

Heparin-associated thrombocytopenia: isolation of the antibody and characterization of a multimolecular PF4-heparin complex as the major antigen.

Sera of 34 patients with heparin-associated thrombocytopenia (HAT), giving a positive result in the serotonin release assay (SRA), were assessed in a platelet factor 4 (PF4)/heparin ELISA. Three sera revealing indeterminate results in the SRA and 10 control sera were also investigated. Both tests correlated closely (Kappa 0.742; p = 2.67 x 10(-7)), but one positive serum in the SRA was negative in the pF4/heparin ELISA. We have isolated the HAT antibodies by absorbtion and elution of HAT sera using endothelial cells (HUVEC). Eluates gave similar results as the sera in the PF4/heparin ELISA (Kappa 0.837, p = 9.26 x 10(-9)), and they also correlated very closely with the SRA (Kappa 0.888; p = 8.89 x 10(-10)). This demonstrates that HAT antibodies bind to the same epitope on platelets and on endothelial cells. High heparin concentrations released PF4 in a dose dependent manner from microtiter plates if PF4/heparin, but not if PF4 alone, was covalently linked. Concomitant to the release of PF4, binding of HAT antibodies to PF4/heparin decreased, as indicated by the median optical density (OD) values of OD 0.88 in the presence of buffer compared to OD 0.181 in the presence of 100 IU/ml heparin. The latter values were similar to those obtained when plates were coated with PF4 alone (median OD 0.203). Binding of three eluates was not inhibited by high heparin concentrations and they reacted also with PF4 alone. We conclude that multimolecular PF4/heparin complexes represent the major antigen in HAT. These multimolecular complexes might present several epitopes and form immune complexes after HAT antibody binding which activate platelets via the FcRII. In a few cases, PF4 alone can be recognized by the antibody. However, there is also evidence that other molecules might be involved in some patients.

Total intravenous anaesthesia with propofol and remifentanil in paediatric patients: a comparison with a desflurane-nitrous oxide inhalation anaesthesia.

BACKGROUND: Remifentanil is a new rapid-acting and ultra-short acting mu-opioid receptor agonist with few reports from use in children. Therefore, we compared a propofol-remifentanil-anaesthesia (TIVA) with a desflurane-N2O-anaesthesia (DN) with particular regard to the recovery of characteristics in children. METHODS: 50 children (4-11 yr) scheduled for ENT surgery were randomly assigned to receive TIVA (n = 25) or DN (N = 25). After standardised i.v. induction of anaesthesia in both groups with remifentanil, propofol and cisatracurium, TIVA was maintained with infusion of propofol and remifentanil. Ventilation was with oxygen in air. DN was maintained with desflurane in 50% N20. The administration of volatile and intravenous anaesthetics was adjusted to maintain a surgical plane of anaesthesia. At the end of surgery all anaesthetics were terminated without tapering and early emergence and recovery were assessed. In addition, side effects were noted. RESULTS: Both anaesthesia methods resulted in stable haemodynamics but significantly higher heart rate with desflurane. Recovery did not differ between the groups except for delayed spontaneous respiration after TIVA. Spontaneous ventilation occurred after 11 +/- 03.7 min versus 7.2 +/- 2.8 min (mean +/- SD, TIVA versus DN), extubation after 11 +/- 3.7 min versus 9.4 +/- 2.9 min, eye opening after 11 +/- 3.9 min versus 14 +/- 7.6 min and Aldrete score > or = 9 after 17 +/- 6.8 min versus 17 +/- 7.5 min. Postoperatively, there was a significant higher incidence of agitation in the DN group (80% vs. 44%) but a low incidence (< 10%) of nausea and vomiting in both groups. CONCLUSION: In children, TIVA with remifentanil and propofol is a well-tolerated anaesthesia method, with a lower peroperative heart rate and less postoperative agitation compared with a desflurane-N2O based anaesthesia.

A set of ordered cosmids and a detailed genetic and physical map for the 8 Mb Streptomyces coelicolor A3(2) chromosome.

A Supercos-1 library carrying chromosomal DNA of a plasmid-free derivative of Streptomyces coelicolor A3(2) was organized into an ordered encyclopaedia of overlapping clones by hybridization. The minimum set of overlapping clones representing the entire chromosome (with three short gaps) consists of 319 cosmids. The average insert size is 37.5 kb and the set of clones therefore divides the chromosome into 637 alternating unique and overlapping segments which have an average length of approx. 12.5 kb. More than 170 genes, gene clusters and other genetic markers were mapped to their specific segment by hybridization to the encyclopaedia. Genes could be cloned by direct transformation and complementation of S. coelicolor mutants with cosmids isolated from Escherichia coli, selecting for insertion into the chromosome by homologous recombination. As in other streptomycetes, the ends of the chromosome have long terminal inverted repeats.