Efficacy of octenidine- and chlorhexidine-based wash-mitts against Candida albicans and Candida auris - a comparative study.

BACKGROUND: Management of outbreaks of the newly emerging pathogen Candida auris may include use of antimicrobial wash-mitts for decolonization. However, currently there is little clinical evidence to support the wide adoption of 'whole-body decolonization' as part of the protocol to effectively manage C. auris outbreaks. The aim of this study was to investigate the chemical tolerance of C. auris compared with the surrogate test organism Candida albicans as established in the European Standards (EN). METHODS: Two commercially available antiseptic-impregnated wash-mitts based on either chlorhexidine digluconate (CHG) or octenidine dihydrochloride (OCT) were studied. Comparison of susceptibility of C. auris and C. albicans was investigated based on the standardized test protocol EN 13624. Experiments were conducted using the impregnation liquid squeezed from the wash-mitts at a contact time of 30 s at different concentrations between 0.5% and 97% in the presence of low organic soiling. FINDINGS: Yeasticidal efficacy according to EN 13624 was found for the OCT wash-mitts at 30 s at ≥10% concentration with C. albicans. In comparison, reduction ≥4 log10 was found at a much lower concentration of ≥1% for both C. auris strains. For the CHG wash-mitts, efficacy against C. albicans was below 2 log10 reduction at 97% concentration within 30 s. Efficacy against the two C. auris strains was around 3 log10 reduction. CONCLUSION: Both C. auris strains were found to be significantly more susceptible when compared with C. albicans. Data also demonstrate that not all antiseptic-impregnated wash-mitts are equally effective against C. auris with OCT having a higher efficacy compared with CHG.

Use of the pour plate technique in tuberculocidal efficacy testing according to EN 14348 - a comparative study.

Effective disinfection strategies are essential to prevent the spread of Mycobacterium tuberculosis. Tuberculocidal efficacy of disinfectants can be demonstrated by testing disinfectants in in-vitro tests, such as the well-established quantitative suspension test EN 14348 using Mycobacterium terrae as a surrogate organism in European disinfectant testing. In other European standard tests, such as EN 13727 and EN 13624, use of the pour plate technique is well established; however, in EN 14348, the spread plate technique alone is considered. Comparative experiments according to EN 14348 with M. terrae were conducted using a peracetic-acid-based disinfectant. Either the pour plate technique or the spread plate technique was used for cultivation. Differences in colony size and morphology were observed when comparing the growth of M. terrae on pour plates compared with spread plates. However, no significant differences in biocidal efficacy data were obtained when applying either spread plates or pour plates in the quantitative suspension test described in EN 14348 under both clean and dirty conditions.

Virucidal efficacy of different formulations for hand and surface disinfection targeting SARS CoV-2.

In the ongoing SARS CoV-2 pandemic, effective disinfection measures are needed, and guidance based on the methodological framework of the European Committee for Standardization (CEN) may enable the choice of effective disinfectants on an immediate basis. This study aimed to elucidate whether disinfectants claiming 'virucidal activity against enveloped viruses' as specified in the European Standard EN 14476 as well as in the German Association for the Control of Viral Diseases/Robert Koch Institute (DVV/RKI) guideline are effectively inactivating SARS-CoV-2. Two commercially available formulations for surface disinfection and one formulation for hand disinfection were studied regarding their virucidal activity. Based on the data of this study the enveloped SARS-CoV-2 is at least equally susceptible compared to the standard test virus vaccinia used in the EN 14476 and DVV/RKI guidelines. Thus, chemical disinfectants claiming 'virucidal activity against enveloped viruses' based on the EN 14476 and DVV/RKI guidelines will be an effective choice to target enveloped SARS-CoV-2 as a preventive measure.

Comparison of the in-vitro efficacy of different mouthwash solutions targeting SARS-CoV-2 based on the European Standard EN 14476.

The outbreak of the SARS-CoV-2 pandemic is triggering a global health emergency alert. Until vaccination becomes available, a bundle of effective preventive measures is desperately needed. Recent research is indicating the relevance of aerosols in the spread of SARS-CoV-2. Thus, in this study commercially available antiseptic mouthwashes based on the active ingredients chlorhexidine digluconate and octenidine dihydrochloride (OCT) were investigated regarding their efficacy against SARS-CoV-2 using the European Standard 14476. Based on the requirement of EN 14476 in which reduction of at least four decimal logarithms (≥4 log10) of viral titre is requested to state efficacy, the OCT-based formulation was found to be effective within a contact time of only 15 s against SARS-CoV-2. Based on this in-vitro data the OCT mouthwash thus constitutes an interesting candidate for future clinical studies to prove its effectiveness in a potential prevention of SARS-CoV-2 transmission by aerosols.

Improved method for tuberculocidal and mycobactericidal activity testing of disinfectants based on the European Standard EN 14348.

Safe measurements to prevent the transmission of (multidrug-resistant) mycobacteria such as disinfection are essential in healthcare settings. In Europe chemical disinfectants are tested for their tuberculocidal and mycobactericidal efficacy by the internationally accepted test procedure described in EN 14348. However, especially for amine-based disinfectants, invalid results may occur by this procedure due to insufficient neutralization. In this multi-laboratory study the procedure described in EN 14348 was optimized by a combination of chemical neutralization and membrane filtration in order to obtain a valid and secure method especially for amine-based disinfectants.

Investigation of the susceptibility of Candida auris and Candida albicans to chemical disinfectants using European Standards EN 13624 and EN 16615.

BACKGROUND: Since the first appearance of Candida auris in 2009, this yeast has become a relevant pathogen in the clinical field. C. auris has been detected on various surfaces in health facilities, and is therefore a target for appropriate disinfection procedures. Preventive measures have to be implemented based on disinfectants with proven efficacy against C. auris. AIM: The chemical tolerance of C. auris was compared with the surrogate test organism Candida albicans as established in the European standards (EN). In this way, conclusions will be drawn as to whether the disinfectants tested according to EN 13624 and EN 16615 are at least equally effective against C. auris. METHODS: The chemical susceptibility of C. auris and C. albicans was investigated using standardized EN test protocols. EN 13624 and EN 16615 were used in this study to examine two commercially available surface disinfectants based on alcohol and quaternary ammonium compounds (QACs), respectively. In addition, the survival rates of the two yeast species were studied on a defined test surface simulating practical conditions. FINDINGS: In comparison with C. albicans, C. auris was found to be significantly more susceptible to the alcohol- and QAC-based disinfectants used in this study. C. albicans was found to be more tolerant to drying on the test surface in EN 16615, yielding higher recovery rates. CONCLUSION: C. albicans is a suitable surrogate test organism when targeting yeasticidal efficacy, which, based on EN 13624 and EN 16615, includes efficacy against the human pathogen C. auris.

Comparison of a rapid detection fluorescence-based assay targeting tuberculocidal efficacy with EN 14348 and EN 14563.

BACKGROUND: A rapid test system using fluorescent Mycobacterium terrae to evaluate the tuberculocidal efficacy of disinfectants has recently been published. Results were obtained in a significantly shorter time than was previously possible. AIM: To compare the European Standard test system with the fluorescence assay and to validate the rapid test system, including particularly the quantitative suspension test. METHODS: Quantitative suspension tests and quantitative carrier tests were carried out according to EN 14348 and EN 14563, respectively. Quantitative carrier tests and subsequent green fluorescent protein (GFP)-based determination of germicidal efficacy were carried out as described previously. A peracetic acid-based formulation was used as a test germicide. FINDINGS: Testing of the germicide in the quantitative suspension test EN 14348 and in the quantitative carrier test EN 14563 revealed tuberculocidal efficacy at a concentration of 1% after 15 min contact time. Accordingly, data obtained from the fluorescence assay demonstrated that a germicide concentration of 1% was effective after 15 min, indicating no live mycobacteria following this treatment. Thus, identical in-use parameters for tuberculocidal efficacy were obtained either by applying the quantitative suspension and quantitative carrier tests EN 14348 and EN 14563 or by using the GFP-based rapid test system. CONCLUSION: The GFP-based rapid test system compares well with the established European Standard test procedure including both phase 2, step 1 and phase 2, step 2 tests and provides a rapid and sensitive tool for testing germicides for relevant in-use concentrations and contact times.

Treatment of water-based metalworking fluids to prevent hypersensitivity pneumonitis associated with Mycobacterium spp.

AIM: To prevent further outbreaks of hypersensitivity pneumonitis (HP), biocides are required which are capable of protecting water-based coolants from proliferating mycobacteria. The aim of this study was therefore, to test different biocide preparations on their mycobactericidal activity. METHODS AND RESULTS: Minimal inhibitory concentration values were determined for Mycobacterium chelonae and Mycobacterium immunogenum for triazine-based, methyloxazolidine-based, N/O-formal-based biocidal formulations. All biocides were effective already at a low dosage (<0.05%) irrespective of the presence or absence of organic soiling, except for one N/O-formal-based formulation containing Kathon 886 (CMI). Quenching of CMI in the presence of organic soiling was found to account for loss in efficacy as determined by high-performance liquid chromatography measurement. Preservation tests were carried out to investigate the efficacy of the biocidal preparations under practical conditions. CONCLUSIONS: Results indicate that methyloxazolidine-based biocidal preparations were most effective to prevent coolants from microbial contamination including rapidly growing mycobacteria. Furthermore, it could be demonstrated that common dipslides can be used to easily monitor coolants for contamination by mycobacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Our data does not support the hypothesis that mycobacterial proliferation is enhanced by the reduction of competitive microbial population by biocides such as triazines as described earlier but rather suggests a protective effect of biocides regarding mycobacteria in the presence of competitive microbial flora, thereby preventing further outbreaks of HP.

Investigation of the hygienic safety of continuous positive airways pressure devices after reprocessing.

With the widespread use of continuous positive airways pressure (CPAP) therapy, the safety of CPAP devices after reprocessing is the subject of debate. In this study, the contamination of CPAP devices and the effectiveness of disinfection was investigated. A total of 122 CPAP devices were examined including 50 CPAP devices used by patients, which were examined before and after reprocessing. Seventy-two new CPAP devices that had not been in contact with patients served as controls. The results of this study show that the microbial contamination of new and used CPAP devices is only minimal. Contaminating micro-organisms were predominantly micro-organisms reflecting the normal environmental microflora such as Penicillium spp., Aspergillus spp., Micrococcaceae and Bacillaceae. Gram-negative species could only be found in rare cases. The data obtained give no indication of poor disinfection of CPAP devices.

Prosodic boundaries, comma rules, and brain responses: the closure positive shift in ERPs as a universal marker for prosodic phrasing in listeners and readers.

Just as the false comma in this sentence, shows punctuation can influence sentence processing considerably. Pauses and other prosodic cues in spoken language serve the same function of structuring the sentence in smaller phrases. However, surprisingly little effort has been spent on the question as to whether both phenomena rest on the same mechanism and whether they are equally efficient in guiding parsing decisions. In a recent study, we showed that auditory speech boundaries evoke a specific positive shift in the listeners' event-related brain potentials (ERPs) that indicates the sentence segmentation and resulting changes in the understanding of the utterance (Steinhauer et al., 1999a). Here, we present three ERP reading experiments demonstrating that the human brain processes commas in a similar manner and that comma perception depends crucially on the reader's individual punctuation habits. Main results of the study are: (1) Commas can determine initial parsing as efficiently as speech boundaries because they trigger the same prosodic phrasing covertly, although phonological representations seem to be activated to a lesser extent. (2) Independent of the input modality, this phrasing is reflected online by the same ERP component, namely the Closure Positive Shift (CPS). (3) Both behavioral and ERP data suggest that comma processing varies with the readers' idiosyncratic punctuation habits. (4) A combined auditory and visual ERP experiment shows that the CPS is also elicited both by delexicalized prosody and while subjects replicate prosodic boundaries during silent reading. (5) A comma-induced reversed garden path turned out to be much more difficult than the classical garden path. Implications for psycholinguistic models and future ERP research are discussed.

How the mass counts: an electrophysiological approach to the processing of lexical features.

Nouns may refer to countable objects such as tables, or to mass entities such as rice. The mass/count distinction has been discussed in terms of both semantic and syntactic features encoded in the mental lexicon. Here we show that event-related potentials (ERPs) can reflect the processing of such lexical features, even in the absence of any feature-related violations. We demonstrate that count (vs mass) nouns elicit a frontal negativity which is independent of the N400 marker for conceptual-semantic processing, but resembles anterior negativities related to grammatical processing. This finding suggests that the brain differentiates between count and mass nouns primarily on a syntactic basis.

Syntactic parsing preferences and their on-line revisions: a spatio-temporal analysis of event-related brain potentials.

The present study investigates the processes involved in the recovery from temporarily ambiguous garden-path sentences. Event-related brain potentials (ERP) were recorded while subjects read German subject-object ambiguous relative and complement clauses. As both clause types are initially analyzed as subject-first structures, object-first structures require a revision which is more difficult for complement than for relative clauses. The hypothesis is tested that the revision process consists of two sub-processes, namely diagnosis and actual reanalysis. Applying a spatio-temporal principal component analysis to the ERP data, distinct positive sub-components presumably reflecting different sub-processes could be identified in the time range of the P300 and P600. It will be argued that the P600 is not a monolithic component, and that different sub-processes may be involved at varying time points depending on the type of garden-path sentence.

The role of knowledge of results in performance and learning of a voice motor task.

The relationship between the provision of Knowledge of Results and the performance and learning of a voice motor task was examined. Thirty adult subjects, randomly assigned to a 100%, 50%, or No Knowledge of Results group, practiced a novel vowel nasalization task. Measures of accuracy and variability obtained during the practice session indicated influence of knowledge of results schedule on the transient effects of motor performance. Deviations from the nasalance target during the retention phase, 5 minutes later, and during a transfer phase, 24 hours later, indicated influence of knowledge of results schedule on the permanent effects of motor learning. Collective results revealed that an increase in relative frequency of knowledge of results led to a decrease in motor performance and learning of a vowel nasalization task: Both accuracy and variability were degraded as knowledge of results increased, with those subjects in the 100% group exhibiting the poorest scores.

Lexical integration: sequential effects of syntactic and semantic information.

Both semantic and syntactic context constraints can influence word processing at the level of lexical integration. In event-related brain potentials (ERPs), semantic integration is reflected by a negativity around 400 msec (N400), whereas phrase structure assignment and syntactic integration are assumed to be reflected by an early left anterior negativity and a late positivity (P600), respectively. An ERP study is presented in which participants read different types of sentences whose terminal verb was either congruent with the preceding context or incongruent due to a phrase structure violation, a semantic violation, or both. The main finding was that only the pure semantic violation condition, but not the combined semantic and syntactic violation condition, elicited a large N400. The two conditions containing phrase structure violations were predominantly characterized by a P600. Both semantic violation conditions, moreover, displayed a late negativity around 700 msec that overlapped with the P600 in the double violation condition. The absence of an N400 effect for elements that are syntactically as well as semantically incongruent with prior context suggests an early influence of phrase structure information on processes of lexical-semantic integration. The present data are discussed in comparison to previous ERP findings, and a new view of lexical integration processes is proposed.

Brain potentials indicate immediate use of prosodic cues in natural speech processing.

Spoken language, in contrast to written text, provides prosodic information such as rhythm, pauses, accents, amplitude and pitch variations. However, little is known about when and how these features are used by the listener to interpret the speech signal. Here we use event-related brain potentials (ERP) to demonstrate that intonational phrasing guides the initial analysis of sentence structure. Our finding of a positive shift in the ERP at intonational phrase boundaries suggests a specific on-line brain response to prosodic processing. Additional ERP components indicate that a false prosodic boundary is sufficient to mislead the listener's sentence processor. Thus, the application of ERP measures is a promising approach for revealing the time course and neural basis of prosodic information processing.

Working memory constraints on syntactic ambiguity resolution as revealed by electrical brain responses.

Parsing strategies in temporarily ambiguous sentences were investigated in readers with different sentence memory capacities using event-related brain potentials (ERPs). Readers with a high memory span as well as readers with a low memory span were required to read subject and object relative sentences which were either ambiguous until the last word (late disambiguation) or were disambiguated by case marking either the clause initial pronoun (immediate disambiguation) or the noun phrase following it (early disambiguation). ERPs registered during sentence reading elicited the following effects: In the late disambiguation condition, high span readers, but not low span readers, displayed a more positive going wave at the disambiguating number marked auxiliary for the object relative sentences than for the subject relative sentences. This positivity is taken to reflect processes of revision that become necessary at the disambiguating element if the initial structure considered is a subject relative clause. When case marking was available in the clause initial at the relative pronoun, both high and low span readers showed a positivity at the disambiguating element for the object relative sentences, suggesting the immediate use of case marking information for revision. When case marking was available in the noun phrase following an ambiguous pronoun both groups showed no clear effect of revision at the disambiguating element, but only at the sentence final number marked auxiliary. This non-immediate use of the case marking information seems to be due to an inherent ambiguity in the German case marking system which interacts with the disambiguating element's position in the sentence. The combined data indicate that morphological information can be used immediately by high and low span readers to resolve syntactic ambiguity during sentence processing whenever the information given is clearly unambiguous. In addition they suggest that possible processing differences in ambiguity resolution between high and low span readers may only appear when the ambiguous regions are long.