Schülke & Mayr GmbH
  • Norderstedt, Germany
Recent publications
To prevent spread of Mycobacterium tuberculosis (Mtb) effective disinfection strategies are essential. 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 M. terrae as a surrogate organism in European disinfectant testing. While in other European standard tests such as EN 13727 or EN 13624 use of pour plate technique is well established, in EN 14348 only spread plate technique is considered. In this study comparative experiments according to EN 14348 with M. terrae were conducted using a peracetic acid-based disinfectant. For cultivation either pour plate or spread plate technique was used. Differences in colony size and morphology were observed when comparing growth of M. terrae on pour versus 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 EN 14348 under both clean and dirty conditions.
The roseobacter group of marine bacteria is characterized by a mosaic distribution of ecologically important phenotypes. These are often encoded on mobile extrachromosomal replicons. So far, conjugation had only been experimentally proven between the two model organisms Phaeobacter inhibens and Dinoroseobacter shibae. Here, we show that two large natural RepABC-type plasmids from D. shibae can be transferred into representatives of all known major Rhodobacterales lineages. Complete genome sequencing of the newly established Phaeobacter inhibens transconjugants confirmed their genomic integrity. The conjugated plasmids were stably maintained as single copy number replicons in the genuine as well as the new host. Co-cultivation of Phaeobacter inhibens and the transconjugants with the dinoflagellate Prorocentrum minimum demonstrated that Phaeobacter inhibens is a probiotic strain that improves the yield and stability of the dinoflagellate culture. The transconjugant carrying the 191 kb plasmid, but not the 126 kb sister plasmid, killed the dinoflagellate in co-culture.
The current pandemic caused by COVID-19 has underlined the importance of a joint effort and approach to ensure patient and health care worker safety in medical care throughout Europe. In addition, the recent flood disasters in Germany and other countries called for immediate joint action, in this case with regard to the prevention of water-borne infections. Environmental disasters will increase with consequences for hospitals and nursing homes. Cooperative efforts are needed for preventing and controlling associated infection outbreaks, new pathogens will appear and a geographic shift of infectious diseases previously not detected in certain areas has already been observed. This approach to infection prevention and control must entail structural as well as regulatory aspects. The principle of equal protection against infections in all European countries must be implemented. Prevention and control of infections, including nosocomial infections, infections caused by antibiotic-resistant bacteria as well as pandemics, need to be based on equal standards in all of Europe. Protection against infections and other public health risks in all European countries is the best guarantor for building trust and identification of citizens in our common Europe. Experts in the fields of hygiene, microbiology, infectiology and epidemiology have to pool the expertise on the prevention and control of infections from different European countries and define key targets for achieving a high standard of hygiene measures throughout Europe. The participants of the Rudolf Schülke Foundation International Symposium call for immediate action and priority to be given to the realization of the proposed 16-point plan.
The parasite Trypanosoma brucei exists in both a bloodstream form (BSF) and a procyclic form (PCF), which exhibit large carbohydrate extensions on the N-linked glycans and glycosylphosphatidylinositol (GPI) anchors, respectively. The parasite’s glycoconjugate repertoire suggests at least 38 glycosyltransferase (GT) activities, 16 of which are currently uncharacterized. Here, we probe the function(s) of the uncharacterised GT67 glycosyltransferase family and a β3 glycosyltransferase (β3GT) superfamily gene, TbGT10. A BSF-null mutant, created by applying the diCre/loxP method in T. brucei for the first time, showed a fitness cost but was viable in vitro and in vivo and could differentiate into the PCF, demonstrating non-essentiality of TbGT10. The absence of TbGT10 impaired the elaboration of N-glycans and GPI anchor sidechains in BSF and PCF parasites, respectively. Glycosylation defects included reduced BSF glycoprotein binding to the lectin ricin and monoclonal antibodies mAb139 and mAbCB1. The latter bind a carbohydrate epitope present on lysosomal glycoprotein p67 that we show here consists of (-6Galβ1-4GlcNAcβ1-)≥4 poly-N-acetyllactosamine repeats. Methylation linkage analysis of Pronase-digested glycopeptides isolated from BSF wild-type and TbGT10 null parasites showed a reduction in 6-O-substituted- and 3,6-di-O-substituted-Gal residues. These data define TbGT10 as a UDP-GlcNAc:βGal β1-6 GlcNAc-transferase. The dual role of TbGT10 in BSF N-glycan and PCF GPI-glycan elaboration is notable, and the β1-6 specificity of a β3GT superfamily gene product is unprecedented. The similar activities of trypanosome TbGT10 and higher-eukaryote I-branching enzyme (EC, which belong to glycosyltransferase families GT67 and GT14, respectively, in elaborating N-linked glycans is a novel example of convergent evolution.
Reservoir souring, which is the production of H 2 S mainly by sulfate-reducing microorganisms (SRM) in oil reservoirs, has been a long-standing issue for the oil industry. While biocides have been frequently applied to control biogenic souring, the effects of biocide treatment are usually temporary, and biocides eventually fail. The reasons behind biocide failure and the long-term response of the microbial community remain poorly understood. In this study, one time biocide treatments with glutaraldehyde (GA) and an aldehyde-releasing biocide (ARB) at low (100 ppm) and high (750 ppm) dosages were individually applied to a complex sulfate-reducing microbial community, followed by one-year monitoring of the chemical responses and the microbial community succession. The chemical results showed that souring control failed after 7 days at 100 ppm dosage regardless the biocide type, and that lasting souring control for the entire one-year timespan was only achieved with ARB at 750 ppm. Microbial community analyses suggested that the high dosage biocide treatments resulted in one order of magnitude lower average total microbial abundance and average SRM abundance compared to the low dosage treatments. The recurrence of souring was associated with reduction of alpha diversity and with long-term microbial community structure change, thus monitoring changes in microbial community metrics may serve as early warnings of the failure of a biocide-based souring control programme in the field. Furthermore, spore-forming sulfate reducers ( Desulfotomaculum and Desulfurispora ) were enriched and became dominant in both GA-treated groups, which could cause challenges to the design of long-lasting remedial souring control strategies. IMPORTANCE Reservoir souring is a detrimental problem for the oil and gas industry as H 2 S corrodes the steel infrastructure, downgrades the oil quality and poses substantial risks to the field personnel and the environment. Biocides have been widely applied to remedy souring, yet the long-term performance of biocide treatments is hard to predict or optimise due to limited understanding of the microbial ecology affected by biocide treatment. This study investigates the long-term biocide performance and associated changes in the abundance, diversity and structure of the souring microbial community, thus advancing the knowledge towards a deeper understanding of the microbial ecology of biocide-treated systems, and contributing to the improvement of current biocide-based souring control practices. The study showcases the potential application of incorporating microbial community analyses to forecast souring and highlights the long-term consequences of the biocide treatment on the microbial communities, with relevance to both operators and regulators.
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) can help to choose 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 national 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 EN 14476 or DVV/RKI guideline. Thus, chemical disinfectants claiming “virucidal activity against enveloped viruses” based on EN 14476 or DVV/RKI guideline will be an effective choice to target enveloped SARS-CoV-2 as a preventive measure.
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 actives chlorhexidine digluconate (CHX) 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 (log10) of viral titer is requested to state efficacy, the OCT-based formulation was found to be effective within a contact time of only 15 sec 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.
Safe measurements to prevent the transmission of (multi-drug-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 can occur by this procedure due to insufficient neutralization. In this multi-lab 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.
When facing an emerging virus outbreak such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a quick reaction time is key to control the spread. It takes time to develop antivirals and vaccines, and implement vaccination campaigns. Therefore, preventive measures such as rapid isolation of cases and identification and early quarantine of cases’ close contacts—as well as masks, physical distancing, hand hygiene, surface disinfection and air control—are crucial to reduce the risk of transmission. In this context, disinfectants and antiseptics with proven efficacy against the outbreak virus should be used. However, biocidal formulations are quite complex and may include auxiliary substances such as surfactants or emollients in addition to active substances. In order to evaluate disinfectants’ efficacy objectively, meaningful efficacy data are needed. Therefore, the European Committee for Standardisation technical committee 216 ‘Chemical disinfectants and antiseptics’ Working Group 1 (medical area) has developed standards for efficacy testing. The European tiered approach grades the virucidal efficacy in three levels, with corresponding marker test viruses. In the case of SARS-CoV-2, disinfectants with proven activity against vaccinia virus, the marker virus for the European claim ‘active against enveloped viruses’, should be used to ensure effective hygiene procedures to control the pandemic.
Chemical disinfection is an indispensable means of preventing infection. This holds true for healthcare settings, but also for all other settings where transmission of pathogens poses a potential health risk to humans and/or animals. Research on how to ensure effectiveness of disinfectants and the process of disinfection, as well as on when, how and where to implement disinfection precautions is an ongoing challenge requiring an interdisciplinary team effort. The valuable resources of active substances used for disinfection must be used wisely and their interaction with the target organisms and the environment should be evaluated and monitored closely, if we are to reliable reap the benefits of disinfection in future generations. In view of the global threat of communicable diseases and emerging and re-emerging pathogens and multidrug-resistant pathogens, the relevance of chemical disinfection is continually increasing. Although this consensus paper pinpoints crucial aspects for strategies of chemical disinfection in terms of the properties of disinfectant agents and disinfection practices in a particularly vulnerable group and setting, i.e., patients in healthcare settings, it takes a comprehensive, holistic approach to do justice to the complexity of the topic of disinfection.
Background Since the first appearance of Candida auris in 2009, this yeast species has become a relevant pathogen in the clinical field. C. auris has been detected on various surfaces in health facilities, thus being 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 examining two commercially available surface disinfectants based on alcohol or 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 When compared to C. albicans C. auris was found to be significantly more susceptible to the tested alcohol-based and the QAC-based disinfectant. C. albicans was found to be more tolerant to drying on the test surface in the quantitative carrier test 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.
The antimicrobial efficacy of antiseptics used in wound management is tested in vitro under standardised conditions according to DIN EN 13727, with albumin and sheep erythrocytes used as organic challenge. However, these testing conditions do not adequately simulate the wound bed environment. Thus, the aim of this study was to compare the efficacy of different antiseptics such as octenidine dihydrochloride (OCT), chlorhexidine digluconate (CHX), polyhexamethylene biguanide (PHMB), and povidone‐iodine under challenge with human wound exudate instead of standardised organic load in an in vitro setting according to DIN EN 13727. Moreover, protein contents, pH, and temperature were compared with standardised testing conditions. The tested antiseptic agents were reduced to different extents based on their bactericidal efficacy, when challenged with human wound exudate compared with standardised conditions. Overall, 0.10% OCT showed the highest effects reaching full efficacy after 30 seconds. CHX and PHMB were the least efficient. Next to the protein content, other components of wound exudate, such as the microflora, seem to influence the efficacy of antiseptics. In summary, the optimisation of in vitro testing conditions in future applications, to more adequately simulate the wound bed environment, will allow a more realistic picture on the potential performance of antiseptics in clinical practice.
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. Thus the aim of this study was 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 by either 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.
Introduction Chemical disinfection is state of the art in preventing spread of infectious agents in the healthcare setting. Additionally, the antimicrobial properties of solid copper alloy surfaces against various microorganisms have recently been substantiated. Thus, antimicrobially active copper surfaces may serve as an additional barrier against distribution of pathogenic microorganisms and be combined with chemical disinfection measures in the hospital. The aim of this study was therefore to investigate on a quantitative basis whether the combination of chemical disinfectants with copper alloy surfaces results in an overall compromised, combined or even synergistic antimicrobial efficacy. Methods Experiments were carried out using the quantitative carrier test devised by the German Society for Hygiene and Microbiology (DGHM) to study antimicrobial efficacy of chemical disinfectants. Requirements for microbicidal efficacy as defined by prEN 14885 were applied. The chemical disinfectants tested in our study contained alcohols (ethanol, 1-propanol), quaternary ammonium compounds (benzalkonium chloride) and glutaraldehyde as actives. Quantitative carrier tests were carried out on different carriers (tiles, copper alloy discs, stainless steel discs) using Pseudomonas aeruginosa, Staphylococcus aureus, Kocuria rhizophila and Candida albicans as test organisms. Results For the alcohol-based disinfectant no difference in antimicrobial efficacy was observed when applied to antimicrobial active copper alloy carriers, tiles or stainless steel discs. For all test organisms microbial contamination was reduced to the detection limit of < 1 log (CFU/ml) within a contact time of 2 min indicating a ≥ 5 log reduction for the tested bacteria and a ≥ 4 log reduction for the yeast, as being requested for chemical disinfectants by prEN 14885. In order to elucidate a potential synergism the chemical disinfectant based on quaternary ammonium compounds (benzalkonium chloride) and glutaraldehyde was used at a sub-effective concentration. Hence, no complete reduction of microbial contamination was achieved on stainless steel or tile carriers for Pseudomonas aeruginosa and Candida albicans. Interestingly, when using copper alloy carriers complete reduction indicating a ≥ 5 log reduction for P. aeruginosa and a ≥ 4 log reduction for C. albicans was detected. Thus, data of this study indicates that solid copper alloy surfaces and disinfectants synergize. Conclusions According to this data, commercially available disinfectants based on alcohol, quaternary ammonium compounds and aldehyde can effectively be combined in a dual strategy with solid copper alloy surfaces to reduce microbial contamination.
In the past years infections caused by multidrug-resistant Gram-negative bacteria have dramatically increased in all parts of the world. This consensus paper is based on presentations, subsequent discussions and an appraisal of current literature by a panel of international experts invited by the Rudolf Schülke Stiftung, Hamburg. It deals with the epidemiology and the inherent properties of Gram-negative bacteria, elucidating the patterns of the spread of antibiotic resistance, highlighting reservoirs as well as transmission pathways and risk factors for infection, mortality, treatment and prevention options as well as the consequences of their prevalence in livestock. Following a global, One Health approach and based on the evaluation of the existing knowledge about these pathogens, this paper gives recommendations for prevention and infection control measures as well as proposals for various target groups to tackle the threats posed by Gram-negative bacteria and prevent the spread and emergence of new antibiotic resistances.
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Norderstedt, Germany