Enterococcus hirae, Enterococcus faecium and Enterococcus faecalis show different sensitivities to typical biocidal agents used for disinfection

Comparative genomic analysis reveals distinct virulence and resistance mechanisms in 21 bacterial fish pathogens

The rising bacterial infections threaten world aquaculture and wild fish populations, making it imperative to increase the understanding of the mechanisms of pathogenic virulence and resistance. This study applies comparative genomic analysis to 21 bacterial fish pathogens, using whole-genome sequences from public genomic resources and sophisticated bioinformatics tools for screening of virulence factors, mobile genetic elements, antibiotic resistance genes, anti-phage defense mechanisms and secretory systems. We have seen that the different pathogens depict a wide range of variability regarding virulence and resistance potential, which may be attributed to species-specific adaptation. Notably, Streptococcus agalactiae and Mycobacterium salmoniphilum were found to possess high offensive and defensive virulence potential, but at different regulative controls. We also found diverse secretion systems and intricate mechanisms for antibiotic resistance, which have provided very important insights into how pathogens adapt to their environments. By categorizing functional genes and finding anti-phage systems, our analysis has revealed new insights into the complex interactions among bacterial virulence, resistance, and host defense mechanisms. These findings not only shed new light on the bacterial pathogenesis process in aquaculture but also provide the bases for focused, therapeutically-based strategies and genomic surveillance programs able to improve disease management and sustainability in aquaculture environments.

Resistance or tolerance? Highlighting the need for precise terminology in the field of disinfection

The terms 'resistance' and 'tolerance' are well defined in the context of antibiotic research. However, in the field of disinfection, these terms are often used synonymously, which creates ambiguity and can lead to misunderstandings and misconceptions. In addition, this inconsistency in terminology makes it difficult to assess the risk of a disinfectant resistance. This general review aims to discuss existing definitions of the terms 'adaptation', 'susceptibility', 'tolerance', 'persistence' and 'resistance' in the light of disinfectants. The most ambiguity is found between tolerance and resistance. Whereas the former describes the not necessarily heritable survival of transient exposure to usually lethal concentrations, resistance is the strictly heritable ability to survive otherwise lethal concentrations of an antimicrobial agent, regardless of exposure time. A simple transfer of experience from antibiotic research is not recommended when assessing the risk of resistance to disinfectants, as there are important differences between antibiotics and disinfectants, although both are antimicrobials: (i) disinfectants are usually applied at concentrations that exceed the minimum inhibitory concentration by orders of magnitude, (ii) the exposure times of disinfectants are in the range of seconds, minutes, or a few hours, (iii) the mode of action of disinfectants is less specific, and (iv) disinfectants often contain more than one active agent with additive or synergistic effects. It is important to recognize that disinfectants, like other antimicrobial agents such as antibiotics, have a dualistic nature and should be used correctly and with caution.

Functional characterization of helminth-associated Clostridiales reveals covariates of Treg differentiation

BACKGROUND

Parasitic helminths influence the composition of the gut microbiome. However, the microbiomes of individuals living in helminth-endemic regions are understudied. The Orang Asli, an indigenous population in Malaysia with high burdens of the helminth Trichuris trichiura, display microbiotas enriched in Clostridiales, an order of spore-forming obligate anaerobes with immunogenic properties. We previously isolated novel Clostridiales that were enriched in these individuals and found that a subset promoted the Trichuris life cycle. In this study, we aimed to further characterize the functional properties of these bacteria.

RESULTS

Clostridiales isolates were profiled for their ability to perform 57 enzymatic reactions and produce short-chain fatty acids (SCFAs) and hydrogen sulfide, revealing that these bacteria were capable of a range of activities associated with metabolism and host response. Consistent with this finding, monocolonization of mice with individual isolates identified bacteria that were potent inducers of regulatory T-cell (Treg) differentiation in the colon. Comparisons between variables revealed by these studies identified enzymatic properties correlated with Treg induction and Trichuris egg hatching.

CONCLUSION

We identified Clostridiales species that are sufficient to induce high levels of Tregs. We also identified a set of metabolic activities linked with Treg differentiation and Trichuris egg hatching mediated by these newly isolated bacteria. Altogether, this study provides functional insights into the microbiotas of individuals residing in a helminth-endemic region. Video Abstract.

Unveiling the efficacy of a bulk Raman spectra-based model in predicting single cell Raman spectra of microorganisms

In a previous publication, we trained predictive models based on Raman bulk spectra of microorganisms placed on a silicon dioxide protected silver mirror slide to make predictions for new Raman spectra, unknown to the models, of microorganisms placed on a different substrate, namely stainless steel. Now we have combined large sections of this data and trained a convolutional neural network (CNN) to make predictions for single cell Raman spectra. We show that a database based on microbial bulk material is conditionally suited to make predictions for the same species in terms of single cells. Data of 13 different microorganisms (bacteria and yeasts) were used. Two of the 13 species could be identified 90% correctly and five other species 71%-88%. The six remaining species were correctly predicted by only 0%-49%. Especially stronger fluorescence in bulk material compared to single cells but also photodegradation of carotenoids are some effects that can complicate predictions for single cells based on bulk data. The results could be helpful in assessing universal Raman tools or databases.

High-Level Extracellular Expression of Hyaluronate Lyase HylP in Bacillus subtilis for Hyaluronan Degradation

Hyaluronate lyase (HA lyase) has potential in the industrial processing of hyaluronan. In this study, HylP, an HA lyase from Streptococcus pyogenes phage (SPB) was successfully expressed in Bacillus subtilis. To improve the extracellular enzyme activity of HylP in B. subtilis, signal peptide engineering systematic optimization was carried out, and cultured it from shake flasks and fermenters, followed by purification, characterization, and analysis of degradation products. The results showed that the replacement of the signal peptide increased the extracellular enzyme activity of HylP from 1.0 × 104 U/mL to 1.86 × 104 U/mL in the shake flask assay, and using a 20 L fermenter in a batch fermentation process, the extracellular enzyme activity achieved the level of 1.07 × 105 U/mL. HylP exhibited significant thermal and pH stability in the temperature range of 40 °C and pH range of 4-8, respectively. The enzyme showed optimum activity at 40 °C and pH 6, with significant activity in the presence of Na+, Mg2+, and Co2+ ions. Degradation analysis showed that HylP efficiently degraded hyaluronan as an endonuclease, releasing unsaturated disaccharides. These comprehensive findings underscore the substantial industrial potential of HylP for hyaluronan processing applications, offering valuable insights into enzyme characterization and optimization of expression for potential industrial utilization.

Enterococcal Membrane Vesicles as Vaccine Candidates

Enterococcus faecium is a leading cause of nosocomial infections, particularly in immunocompromised patients. The rise of multidrug-resistant E. faecium, including Vancomycin-Resistant Enterococci (VRE), is a major concern. Vaccines are promising alternatives to antibiotics, but there is currently no vaccine available against enterococci. In a previous study, we identified six protein vaccine candidates associated with extracellular membrane vesicles (MVs) produced by nosocomial E. faecium. In this study, we immunized rabbits with two different VRE-derived MV preparations and characterized the resulting immune sera. Both anti-MV sera exhibited high immunoreactivity towards the homologous strain, three additional VRE strains, and eight different unrelated E. faecium strains representing different sequence types (STs). Additionally, we demonstrated that the two anti-MV sera were able to mediate opsonophagocytic killing of not only the homologous strain but also three unrelated heterologous VRE strains. Altogether, our results indicate that E. faecium MVs, regardless of the purification method for obtaining them, are promising vaccine candidates against multidrug-resistant E. faecium and suggest that these naturally occurring MVs can be used as a multi-antigen platform to elicit protective immune responses against enterococcal infections.

Exploring Peracetic Acid and Acidic pH Tolerance of Antibiotic-Resistant Non-Typhoidal Salmonella and Enterococcus faecium from Diverse Epidemiological and Genetic Backgrounds

Acid stress poses a common challenge for bacteria in diverse environments by the presence of inorganic (e.g., mammals' stomach) or organic acids (e.g., feed additives; acid-based disinfectants). Limited knowledge exists regarding acid-tolerant strains of specific serotypes, clonal lineages, or sources in human/animal pathogens: namely, non-typhoidal Salmonella enterica (NTS) and Enterococcus faecium (Efm). This study evaluated the acidic pH (Mueller-Hinton acidified with HCl) and peracetic acid (PAA) susceptibility of Efm (n = 72) and NTS (n = 60) from diverse epidemiological/genetic backgrounds and with multiple antibiotic resistance profiles. Efm minimum growth/survival pH was 4.5-5.0/3.0-4.0, and for NTS it was 4.0-4.5/3.5-4.0. Efm distribution among acidic pH values showed that only isolates of clade-non-A1 (non-hospital associated) or the food chain were more tolerant to acidic pH compared to clade-A1 (hospital-associated clones) or clinical isolates (p < 0.05). In the case of NTS, multidrug-resistant (MDR) isolates survived better in acidic pH (p < 0.05). The PAA MIC/MBC for Efm was 70-120/80-150 mg/L, and for NTS, it was 50-70/60-100 mg/L. The distribution of Efm among PAA concentrations showed that clade-A1 or MDR strains exhibited higher tolerance than clade-non-A1 or non-MDR ones (p < 0.05). NTS distribution also showed higher tolerance to PAA among non-MDR and clinical isolates than food chain ones (p < 0.05) but there were no differences among different serogroups. This unique study identifies specific NTS or Efm populations more tolerant to acidic pH or PAA, emphasizing the need for further research to tailor controlled measures of public health and food safety within a One Health framework.

Functional characterization of helminth-associated Clostridiales reveals covariates of Treg differentiation

Parasitic helminths influence the composition of the gut microbiome. However, the microbiomes of individuals living in helminth-endemic regions are understudied. The Orang Asli, an indigenous population in Malaysia with high burdens of the helminth Trichuris trichiura, displayed microbiotas enriched in Clostridiales, an order of spore-forming obligate anaerobes previously shown to have immunogenic properties. We previously isolated novel Clostridiales that were enriched in these individuals and found that a subset promoted the Trichuris life cycle. Here, we further characterized the functional properties of these bacteria. Enzymatic and metabolomic profiling revealed a range of activities associated with metabolism and host response. Consistent with this finding, monocolonization of mice with individual isolates identified bacteria that were potent inducers of regulatory T cell (Treg) differentiation in the colon. Comparisons between variables revealed by these studies identified enzymatic properties correlated with Treg induction and Trichuris egg hatching. These results provide functional insights into the microbiotas of an understudied population.

Evolving the EN 1500 test method for alcohol-based hand rub closer to clinical reality by reducing the organic load on hands and enabling product to be applied to dry hands

BACKGROUND

The methods currently used in Europe and North America to evaluate the bactericidal efficacy of hand hygiene products have some limitations, e.g., in the selection of test organisms or the method of contamination, and none of the methods allows prediction of actual clinical efficacy. WHO has therefore proposed to develop methods that better reflect typical clinical reality.

METHODS

In a first experiment, we investigated two contamination methods (immersion according to EN 1500 and low-volume according to ASTM E2755) with the EN 1500 test organism Escherichia coli and using 60% v/v iso-propanol. The second experiment was for comparison of the two contamination methods with Enterococcus faecalis. Finally, the two test organisms were compared using the low-volume contamination method. Data within each experiment was statistically compared using the Wilcoxon test for paired samples and data from all experiments were combined and fit to linear mixed effects models.

RESULTS

Mixed-effects analysis confirmed that the test organism and contamination method both impacted the pre-values and all three of these were factors that influenced log₁₀ reductions. Higher pre-values resulted in significantly higher log₁₀ reductions, immersion contributed to significantly higher log₁₀ reductions, and E. coli affected significantly lower log₁₀ reductions.

CONCLUSION

An efficacy evaluation against E. faecalis with a low-volume contamination method could be considered as an alternative to the EN 1500 standard. This could help improve the clinical relevance of the test method with including a Gram-positive organism and reducing soil load which allows a product application closer to reality.

Evaluation of a novel porous antimicrobial media for industrial and HVAC water biocontrol

A novel treatment method, consisting of pea-gravel with a marine coating supplemented with alkyldimethylbenzylammonium chloride (ADBAC or benzalkonium chloride), has been examined for its antimicrobial performance and coating stability in aqueous environments. Initial column studies examining the porous media's ability to reduce bacterial loads in heating, ventilation, and air conditioning (HVAC) water found average reductions of 94% from pre-flush levels (10⁶ colony forming unit (CFU)/mL) when assessed with R2A spread plates and 83% reductions with SimPlates. There was no observed statistical difference between the average of pre- and post-flush waters from four tests of the media without ADBAC. Taxonomic identification, by 16S rRNA gene sequencing, of colonies drawn from pre- and post-ABDAC R2A plates showed similarities with taxa observed in high frequency from prior cultivation-independent surveys of other cooling tower systems. With this proof of concept, two versions of the media were evaluated for potential coating components released during aqueous exposure. Neither released measurable volatile organic compounds (VOC) components, but one did release bisphenol A and ABDAC compounds. Subsequent column tests of the more durable coating were conducted using cultures of interest in industrial water and demonstrated significant reductions in neutralized post-column Enterococcus faecalis samples and near complete loss of Legionella pneumophila in non-neutralized fluids, but lower reductions in Pseudomonas aeruginosa.

Clostridia isolated from helminth-colonized humans promote the life cycle of Trichuris species

Soil-transmitted intestinal worms known as helminths colonize over 1.5 billion people worldwide. Although helminth colonization has been associated with altered composition of the gut microbiota, such as increases in Clostridia, individual species have not been isolated and characterized. Here, we isolate and sequence the genome of 13 Clostridia from the Orang Asli, an indigenous population in Malaysia with a high prevalence of helminth infections. Metagenomic analysis of 650 fecal samples from urban and rural Malaysians confirm the prevalence of species corresponding to these isolates and reveal a specific association between Peptostreptococcaceae family members and helminth colonization. Remarkably, Peptostreptococcaceae isolated from the Orang Asli display superior capacity to promote the life cycle of whipworm species, including hatching of eggs from Trichuris muris and Trichuris trichiura. These findings support a model in which helminths select for gut colonization of microbes that support their life cycle.

Evaluation of the microbial reduction efficacy and perception of use of an ozonized water spray disinfection technology

The development of new approaches for the decontamination of surfaces is important to deal with the processes related to exposure to contaminated surfaces. Therefore, was evaluated the efficacy of a disinfection technology using ozonized water (0.7-0.9 ppm of O3) on the surfaces of garments and accessories of volunteers, aiming to reduce the spread of microbial pathogens in the workplace and community. A Log10 microbial reduction of 1.72-2.40 was observed between the surfaces tested. The microbial reductions remained above 60% on most surfaces, and this indicated that the disinfection technology was effective in microbial log reduction regardless of the type of transport used by the volunteers and/or their respective work activities. In association with the evaluation of efficacy, the analysis of the perception of use (approval percentage of 92.45%) was fundamental to consider this technology as an alternative for use as a protective barrier, in conjunction with other preventive measures against microbiological infections, allowing us to contribute to the availability of proven effective devices against the spread of infectious agents in the environment.

Enterococcus Virulence and Resistant Traits Associated with Its Permanence in the Hospital Environment

Enterococcus are opportunistic pathogens that have been gaining importance in the clinical setting, especially in terms of hospital-acquired infections. This problem has mainly been associated with the fact that these bacteria are able to present intrinsic and extrinsic resistance to different classes of antibiotics, with a great deal of importance being attributed to vancomycin-resistant enterococci. However, other aspects, such as the expression of different virulence factors including biofilm-forming ability, and its capacity of trading genetic information, makes this bacterial genus more capable of surviving harsh environmental conditions. All these characteristics, associated with some reports of decreased susceptibility to some biocides, all described in this literary review, allow enterococci to present a longer survival ability in the hospital environment, consequently giving them more opportunities to disseminate in these settings and be responsible for difficult-to-treat infections.

The application of normative documents for determination of biocidal activity of disinfectants and antiseptics dedicated for medical area: a narrative review

Disinfectants and antiseptics are important weapons to reduce the number of microorganisms and thus to limit the number of infections. Different methods of antimicrobial activity testing, often not standardised, without appropriate controls and not validated are applied. To address these issues, several European Standards (EN) have been developed, describing the test methods to determine whether chemical disinfectants or antiseptic products have appropriate bactericidal, sporicidal, mycobactericidal or tuberculocidal activity; fungicidal or yeasticidal activity; or virucidal activity. In this narrative review, the 17 EN concerning evaluation of the above-mentioned antimicrobial activity of preparations dedicated to the medical area are briefly reviewed, together with recent publications on this topic. Suspension and carrier tests have been performed in clean and dirty conditions simulating the medical area. In addition, a wide range of applications of these standards has been presented in the research of biocides for hand antisepsis, surfaces disinfection, including airborne disinfection as well as medical device and medical textile disinfection. The role of normative documents in the investigation of antimicrobial activity of disinfectants and antiseptics to limit infections has been underestimated. This narrative review aims to persuade researchers to conduct antimicrobial activity testing in line with validated EN and highlights an existing gap in ongoing research. It also aims to raise awareness of the wide range of biocidal activity tests with standardised methods in medical area. We also pay attention to the recently developed European Pharmacopoeia monography concerning the testing of bactericidal and fungicidal activity of antiseptics classified as medicinal products.

Bactericidal efficiency of preparation based on essential oils used in aerosol disinfection in the presence of poultry

A disinfectant was created for aerosol disinfection of premises in the presence of poultry, which will help reduce microbial contamination of premises, increase survival, weight of poultry and economic efficiency of meat production in general. The preparation based on essential oils can be used for disinfection in the presence of poultry and at the same time exhibits a therapeutic and prophylactic effect on respiratory infections. This disinfectant has a colloidal solution of silver (Ag), benzalkonium chloride and essential oils of thyme, fir and eucalyptus. The preparation based on essential oils contains (per 100 g): benzalkonium chloride – 16.0 g; thyme oil – up to 2.0 g; eucalyptus oil – up to 2.0 g; fir oil – up to 2.0 g; colloidal solution of silver (Ag) – 20–30 mg; distilled water - up to 100 cm3. Aerosol sanitation of indoor air was carried out with 0.3% solution of preparation in the period before housing poultry and once a day from the 20th to the 35th day of growing broilers with aerosol cold mist generator Dyna-Fog Tornado (model 2897, construction type – ULV-electric spray gnerator, manufacturer – Curtis Dyna-Fog, Ltd., USA) at a dose of 50.0 cm3 per 1 m3 at an exposure of 60 minutes. The size of the aerosol particles is 20 μm. On days 1, 4, 8, 11, 15, 28, 37, and 42, the chickens were weighed, and the blood was taken for examination. Blood was examined to study the number of red blood cells, hemoglobin content, the bactericidal activity of blood serum, phagocyte activity of leukocytes, lysozyme activity of blood serum. According to the results of the research, the technological modes of air disinfection of poultry premises in the presence of broiler chickens were substantiated during the use of preparation, which contains nanoparticles (NP) of silver, benzalkonium chloride and essential oils. The optimal mode of aerosol treatment of poultry houses using a 0.3% solution preparation based on essential oils is 50 mL/m3 of a room with a 60-minute exposure. The use of air disinfection in the presence of chickens during broiler rearing and one treatment per day from 20 to 35 days of the chickens’ growth reduced the microbial pollution of indoor air. Thus, the concentration of microbial cells in the room where the chickens were kept was 230.2 ± 15.6 thousand microbial cell/m3. Sixty minutes after disinfection, the concentration decreased to 1.4 ± 0.4 thousand microbial cell/m3. In addition, the bodyweight of chickens at 6 weeks increased by 449.4 ± 16.3 g (15.9%) compared with the controls. The method and mode of air treatment did not adversely affect the development of the internal organs of the poultry and their physiological state, which is confirmed by studies of the morphological parameters of the chicken blood. The data obtained indicate a positive effect of the developed methods and modes of aerosol air treatment with the preparation based on essential oils on the growth and development of broilers.

Assessment of Microbial Reduction by Cage Washing and Thermal Disinfection using Quantitative Biologic Indicators for Spores, Viruses and Vegetative Bacteria

Cage washing is a key process of the biosecurity program in rodent facilities. For the current study, we developed systems (i. e., magnet attachments, quantitative biologic indicators (Q-BI), and measurement of thermal disinfection at equipment level) to assess the microbial decontamination achieved by a rodent equipment washer with and without thermal disinfection. 99% of the magnets remained in position to hold Q-BI and temperature probes inside cages, water bottles or at equipment level across a cabinet washer chamber with loads dedicated to either housing or drinking devices. Various types of Q-BI for Bacillus atrophaeus, Enterococcus hirae and minute virus of mice were tested. To simulate potential interference from biologic material and animal waste during cage processing, Q-BI contained test soil: bovine serum albumin with or without feces. As a quantitative indicator of microbial decontamination, the reduction factor was calculated by comparing microbial load of processed Q-BI with unprocessed controls. We detected variation between Q-BI types and assessed the washer's ability to reduce microbial load on equipment. Reduction factor results were consistent with the Q-BI type and showed that the washing and thermal disinfection cycle could reduce loads of vegetative bacteria, virus and spore by 5 log₁₀ CFU/TCID₅₀ and beyond. Thermal disinfection was monitored with temperature probes linked to data loggers recording live. We measured the period of exposure to temperatures above 82.2 °C, to calculate A₀, the theoretical indicator for microbial lethality by thermal disinfection, and to assess whether the cabinet washer could pass the minimum quality standard of A₀ = 600. Temperature curves showed an A₀ > 1000 consistently across all processed equipment during thermal disinfection. These data suggest that, when sterilization is not required, a cabinet washer with thermal disinfection could replace an autoclave and reduce environmental and financial waste.

Potential application of novel technology developed for instant decontamination of personal protective equipment before the doffing step

The use of personal protective equipment (PPE) has been considered the most effective way to avoid the contamination of healthcare workers by different microorganisms, including SARS-CoV-2. A spray disinfection technology (chamber) was developed, and its efficacy in instant decontamination of previously contaminated surfaces was evaluated in two exposure times. Seven test microorganisms were prepared and inoculated on the surface of seven types of PPE (respirator mask, face shield, shoe, glove, cap, safety glasses and lab coat). The tests were performed on previously contaminated PPE using a manikin with a motion device for exposure to the chamber with biocidal agent (sodium hypochlorite) for 10 and 30s. In 96.93% of the experimental conditions analyzed, the percentage reduction was >99% (the number of viable cells found on the surface ranged from 4.3x106 to <10 CFU/mL). The samples of E. faecalis collected from the glove showed the lowest percentages reduction, with 86.000 and 86.500% for exposure times of 10 and 30 s, respectively. The log10 reduction values varied between 0.85 log10 (E. faecalis at 30 s in glove surface) and 9.69 log10 (E. coli at 10 and 30 s in lab coat surface). In general, E. coli, S. aureus, C. freundii, P. mirabilis, C. albicans and C. parapsilosis showed susceptibility to the biocidal agent under the tested conditions, with >99% reduction after 10 and 30s, while E. faecalis and P. aeruginosa showed a lower susceptibility. The 30s exposure time was more effective for the inactivation of the tested microorganisms. The results show that the spray disinfection technology has the potential for instant decontamination of PPE, which can contribute to an additional barrier for infection control of healthcare workers in the hospital environment.

Technological Advances in Ozone and Ozonized Water Spray Disinfection Devices

To control infectious diseases such as the severe acute respiratory syndrome coronavirus (Covid-19) that caused the current pandemic, disinfection measures are essential. Among building measures, disinfection chambers can help to decrease the transmission rate through the sanitizing capacity of the disinfectant used, which can thereby clean surfaces or humans. Out of existing biocides, ozone is considered one of the safest for humans, but one of the most powerful oxidizers, making the substance a better alternative as the biocidal solution in disinfection chambers. Analyses were carried out by using all patented documents related to disinfection chambers that used ozone as a disinfectant. A Derwent Innovation Index (DII) database search was undertaken to find these patents. Patent prospecting resulted in 620 patent documents that were divided into 134 patent families. There was no technology related to protective barriers for individuals, and the majority of patents in the retrieved data aimed at sterilizing medical devices and surfaces. Given that the specific Cooperative Patent Classification (CPC) code for ozone dissolved in liquid was used in the methodology search, but not included among the 10 most used codes in the patents, the use of ozonized water may be an innovative approach in the technology landscape of sterilization chambers.