Sporicidal Activity Research Articles

Potential effectiveness of parenteral nemonoxacin in the treatment of Clostridioides difficile infections: in vitro, ex vivo, and mouse studies.

Antimicrobial therapy plays a crucial role in the management of CDI patients. However, the standard agent for treating CDIs is limited to oral fidaxomicin or vancomycin. For patients made nil by mouth, there is a clinically urgent and essential need to develop an intravenous antibiotic. For C. difficile with the lowest MIC of nemonoxacin and vancomycin, the inhibitory effects were tested using the kinetic time-kill assay and ex vivo co-culture model. The effectiveness of nemonoxacin and vancomycin in inhibiting spore germination, the sporicidal activity, and the treatment of mice with CDIs were compared. For clinical isolates and laboratory strains, lower MICs of nemonoxacin against C. difficile than levofloxacin and ciprofloxacin were observed, even in those harboring point mutations in the quinolone-resistance determining region. Although nemonoxacin failed to suppress spore outgrowth and germination in C. difficile, it exhibited an effective inhibitory effect against C. difficile in the kinetic time-kill assay and the ex vivo co-culture model. Mice receiving intraperitoneal nemonoxacin had less weight loss, higher cecum weight, a longer colon length, and lower expression of the tcdB gene, compared with untreated mice. Notably, there were no significant differences observed in weight loss, cecum weight, colon length, or tcdB gene expression between mice treated with vancomycin and those treated with any dose of nemonoxacin. Similarly, no significant differences were found between mice receiving combination therapy of intraperitoneal nemonoxacin plus oral vancomycin and those treated with intraperitoneal nemonoxacin or oral vancomycin alone. The potential role of nemonoxacin, which can be administered parenterally, for treating CDIs was evidenced through the in vitro, ex vivo, and mouse models.

Phytochemical Screening and Evaluation of Antibacterial, Anticandidal, and Sporicidal Properties of Euphorbia tirucalli Extract in Terengganu, Malaysia

Euphorbia tirucalli, commonly known as the pencil cactus or milk bush plant, is used as an alternative medicine. The current study evaluated the phytochemical contents, antibacterial, anticandidal, and antisporicidal potential of the E. tirucalli methanolic extract. The antibacterial and anticandidal activity of E. tirucalli methanolic extract was determined by performing a disc diffusion assay, MIC, MBC, and MCC. The sporicidal activity was tested at different concentrations of extract and exposure times. Phytochemical analyses revealed the presence of alkaloids, saponins, cardiac glycosides, terpenoids, and tannins in E. tirucalli methanolic extract. Results demonstrated inhibition zones of the extract against Gram-positive bacteria were in range of 22.00-7.00 mm. Meanwhile, inhibition zones of the extract against Gram-negative bacteria were in range of 13.00-7.00 mm. All bacteria were inhibited with MIC values at 1.56-25.0 mg/ml and can be completely killed with MBC values of 20-200 mg/ml. Inhibition zones of E. tirucalli methanolic extract against Candida spp. were in the range of 20.00-8.00 mm. All Candida spp. were inhibited with MIC values at 1.56-100.00 mg/ml and MBC values of 100-300 mg/ml. All concentrations of the extract inhibited all Bacillus spp. spores at different exposure times. In conclusion, the methanolic extract of E. tirucalli exhibits antibacterial, anticandidal, and sporicidal activities. The findings indicated that the methanolic extract of E. tirucalli has good potential for prospective nature-based antimicrobial agents.

Anthelminthic and antimicrobial effects of hedge woundwort (Stachys sylvatica L.) growing in Southern Kazakhstan.

The Stachys L. genus has been widely used in traditional medicine in many countries throughout the world. The study aimed to investigate the chemical composition and bioactivity of the hydroethanolic extract (50% v/v) obtained by ultrasonication from the aerial flowering parts of Stachys sylvatica L. (SSE) collected in Almaty region (Southern Kazakhstan). According to RP-HPLC/PDA analysis the leading metabolites of the SSE belonged to polyphenols: chlorogenic acid and its isomers (2.34mg/g dry extract) and luteolin derivatives (1.49mg/g dry extract), while HPLC-ESI-QTOF-MS/MS-based qualitative fingerprinting revealed the presence of 17 metabolites, mainly chlorogenic acid and its isomers, flavonoid glycosides, and verbascoside with its derivatives. GC-MS analysis of the volatile metabolites showed mainly the presence of diterpenoids and fatty acid esters. A reduction in the viability of nematodes Rhabditis sp. was obtained for the SSE concentration of 3.3mg/mL, while 11.1mg/mL showed activity comparable to albendazole. The SSE exhibited higher activity against Gram-positive (MIC = 0.5-2mg/mL) than Gram-negative bacteria and yeast (MIC = 8mg/mL), exerting bactericidal and fungicidal effects but with no sporicidal activity. The SSE showed some antiviral activity against HCoV-229E replicating in MRC-5 and good protection against the cytopathic effect induced by HHV-1 in VERO. The SSE was moderately cytotoxic towards human cervical adenocarcinoma (H1HeLa) cells (CC50 of 0.127mg/mL after 72h). This study provides novel information on the SSE extract composition and its biological activity, especially in the context of the SSE as a promising candidate for further antiparasitic studies.

Analysis of the effectiveness of a new antimicrobial agent for disinfection in veterinary practice

The loss of effectiveness of standard treatment methods and the increased risk of rapid spread of infections are serious consequences of this problem. This underscores the need to develop new approaches to combating pathogen resistance and ensuring effective control of infections. Studies of antimicrobial activity were conducted on strains of C. albicans, A. niger, and B. subtilis. The minimal fungicidal concentration was determined based on the growth of microorganisms C. albicans, A. niger on Sabouraud agar media containing different concentrations of a new substance – a derivative of thiadiazole. The sporicidal activity was determined by culturing the test culture B. subtilis in meat-peptone broth, followed by seeding on meat-peptone agar. Sporicidal activity was determined by inoculating the test culture of B. subtilis into meat-peptone broth, followed by plating on meat-peptone agar. Control assays were performed by inoculating the test cultures on corresponding media without the test substances. The new disinfectant – a derivative of thiadiazole – demonstrated high antimicrobial activity. The aim of this research was to study the new chemical substance for antimicrobial (antifungal and sporicidal) activity and the creation of new types of biocides. The studies showed that the minimum fungicidal concentration of the 0.3% solution in a 30% alcohol solution against C. albicans RCPGY401 was 1.56 ± 1.06 μg/mL, A. niger 137a – 1.56 ± 1.29 μg/mL. Furthermore, the material exhibited sporicidal activity against B. subtilis ATCC 10702, with an effective concentration of – 3.12 ± 1.34 μg/mL. The research confirms the activity of the new compound against the studied microorganisms and allows for its recommendation for further study (treatment regimens, safety, control methods, etc.) for use in veterinary practice for various treatment purposes.

Rosin as a Natural Alternative for the effective disinfection of ESKAPE Pathogens and Clostridioides difficile spores.

Hospital-acquired infections (HAIs) caused by antimicrobial-resistant ESKAPE pathogens are a significant concern for the healthcare industry, with an estimated cost of up to ${\$}$45 billion per year in the US alone. Clostridioides difficile is an additional opportunistic pathogen that also poses a serious threat to immunocompromised patients in hospitals. Infections caused by these pathogens lead to increased hospital stays and repeated readmission, resulting in a significant economic burden. Disinfectants and sporicidals are essential to reduce the risk of these pathogens in hospitals, but commercially available products can have a number of disadvantages including inefficacy, long contact times, short shelf lives, and operator health hazards. In this study we evaluated the effectiveness of Rosin (a natural substance secreted by coniferous trees as a defence mechanism against wounds in tree bark) and its commercial derivative Rosetax-21 as disinfectants and sporicidal against the six ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) and spore preparations from Clostridioides difficile. Both Rosin and Rosetax-21 were tested under simulated clean and dirty conditions (with BSA) against the ESKAPE pathogens, and C. difficile spore preparations. In clean conditions, Rosin (5% weight/volume: w/v) demonstrated significant efficacy against five of the ESKAPE pathogens, with A. baumannii and E. faecium being the most susceptible, and K. pneumoniae the most resistant, showing only a one-log reduction after a 5min treatment. However, in dirty conditions, all pathogens including K. pneumoniae exhibited at least a 3-log reduction to Rosin within 5min. Rosetax-21 (5%w/v) was found to be less effective than Rosin in clean conditions, a trend that was exacerbated in the presence of BSA. Additionally, both Rosin and Rosetax-21 at 2.5% (w/v) achieved complete eradication of C. difficile spores when combined with 0.5% glutaraldehyde, though their standalone sporicidal activity was limited. The findings from this study highlight the potential of Rosin and Rosetax-21 as both bactericidal and sporicidal disinfectants, with their efficacy varying based on the conditions and the pathogens tested. This presents an avenue for the development of novel healthcare disinfection strategies, especially against HAIs caused by antimicrobial-resistant ESKAPE pathogens and C. difficile.

Light-Driven Tetra- and Octa-β-substituted Cationic Zinc(II) Phthalocyanines for Eradicating Fusarium oxysporum Conidia

Photodynamic inactivation (PDI) is an emerging therapeutic approach that can effectively inactivate diverse microbial forms, including vegetative forms and spores, while preserving host tissues and avoiding the development of resistance to the photosensitization procedure. This study evaluates the antifungal and sporicidal photodynamic activity of two water-soluble amphiphilic tetra- and octa-β-substituted zinc(II) phthalocyanine (ZnPc) dyes with dimethylaminopyridinium groups at the periphery (ZnPcs 1, 2) and their quaternized derivatives (ZnPcs 1a, 2a). Tetra(1, 1a)- and octa(2, 2a)-β-substituted zinc(II) phthalocyanines were prepared and assessed as photosensitizers (PSs) for their effects on Fusarium oxysporum conidia. Antimicrobial photoinactivation experiments were performed with each PS at 0.1, 1, 10, and 20 µM under white light irradiation at an irradiance of 135 mW·cm–2, for 60 min (light dose of 486 J·cm−2). High PDI efficiency was observed for PSs 1a, 2, and 2a (10 µM), corresponding to inactivation until the method’s detection limit. PS 1 (20 µM) also achieved a considerable reduction of >5 log10 in the concentration of viable conidia. The quaternized PSs (1a, 2a) showed better PDI performance than the non-quaternized ones (1, 2), even at the low concentration of 1 µM, and a light dose of 486 J·cm−2. These cationic phthalocyanines are potent photodynamic drugs for antifungal applications due to their ability to effectively inactivate resistant forms, like conidia, with low concentrations and reasonable energy doses.

Novel metal peroxide nanoboxes restrain Clostridioides difficile infection beyond the bactericidal and sporicidal activity.

Clostridioides difficile spores are considered as the major source responsible for the development of C. difficile infection (CDI), which is associated with an increased risk of death in patients and has become an important issue in infection control of nosocomial infections. Current treatment against CDI still relies on antibiotics, which also damage normal flora and increase the risk of CDI recurrence. Therefore, alternative therapies that are more effective against C. difficile bacteria and spores are urgently needed. Here, we designed an oxidation process using H2O2 containing PBS solution to generate Cl- and peroxide molecules that further process Ag and Au ions to form nanoboxes with Ag-Au peroxide coat covering Au shell and AgCl core (AgAu-based nanoboxes). The AgAu-based nanoboxes efficiently disrupted the membrane structure of bacteria/spores of C. difficile after 30-45 min exposure to the highly reactive Ag/Au peroxide surface of the nano structures. The Au-enclosed AgCl provided sustained suppression of the growth of 2 × 107 pathogenic Escherichia coli for up to 19 days. In a fecal bench ex vivo test and in vivo CDI murine model, biocompatibility and therapeutic efficacy of the AuAg nanoboxes to attenuate CDI was demonstrated by restoring the gut microbiota and colon mucosal structure. The treatment successfully rescued the CDI mice from death and prevented their recurrence mediated by vancomycin treatment. The significant outcomes indicated that the new peroxide-derived AgAu-based nanoboxes possess great potential for future translation into clinical application as a new alternative therapeutic strategy against CDI.

Controlling vegetative cells and spores growth of Bacillus spp. using ethanolic Ketapang (Terminalia catappa L.) leaf extract

Terminalia catappa L. is a large, spreading type of tree which usually grows in tropical environment, especially at coastal area with sandy stones. The current study evaluated anti-Bacillus potential of the ethanolic ketapang (Terminalia catappa L.) leaf extract (EKLE) as antibacterial and sporicidal agent against vegetative cells and spores of Bacillus spp. The antibacterial activity of EKLE against Bacillus spp. (B. cereus ATCC33019, B. pumilus ATCC14884, B. subtilis ATCC6633 and B. megaterium ATCC14581) vegetative cells were determined by performing well diffusion assay (WDA), minimum inhibition concentration (MIC), minimum bacterial concentration (MBC) and time-kill curve analyses. The sporicidal activity was tested at different concentrations of EKLE. Then, the extract's stability in terms of antibacterial and sporicidal activities upon exposure to different temperatures and pHs were carried out. Results demonstrated inhibition zones of EKLE against Bacillus spp. was in the range of 9.25 ± 0.75 mm - 11.67 ± 0.47 mm. All vegetative cells of Bacillus spp. were inhibited with MIC values at 0.63–1.25 mg/mL and can be completely killed with MBC values of 0.63 - >5.00 mg/mL. Time-kill analysis showed all the Bacillus spp. tested can be completely killed at concentrations of 2.50–5.00 mg/mL from 1 to 4 h. EKLE concentration of 1% (w/v) completely killed all Bacillus spp. spores at different exposure time. The antibacterial and sporicidal activities of EKLE were not affected by exposure to different temperatures (4, 30, 50, 80 and 121 °C) and pHs (3, 7 and 10), revealing the stability of the extract against different conditions. In conclusion, Terminalia catappa L. leaf exhibits antibacterial and sporicidal activities against Bacillus spp., therefore, the extract can be developed as anti-Bacillus agent, paving the way for its utilization in food industry as a natural food preservative.

Effectiveness Evaluation of Viti's vinifera Leaf Extract on the Viability of Echinococcus Eggs and Protoscolices In Vitro.

Echinococcosis is a zoonotic disease caused by the genus Echinococcus. Globally, it is one of the most central helminthic diseases. Surgery remains the method of choice to remove cystic Echinococcus. Various sporicidal agents have been used to invalidate the substances in hydatid cysts. Nevertheless, many sporicidal agents cause inflammation and can cause side complications, so their use should be limited. The study aims to evaluate the effectiveness of Vitis vinifera leaf methanolic extract as a sporicidal agent for Echinococcus eggs and protoscolices and determines the best concentration. The mortality and viability of protoscolices were measured in samples exposed to four concentrations of V. vinifera leaf extract (VVLE) (5, 10, 30, and 50 mg/mL) for 5, 10, 20, and 30 min and in eggs exposed to three concentrations (100, 200, and 300 mg/mL) for 24 and 48 h. An infrared spectroscopy chemical test was conducted to assess the presence of numerous expected active components in the extract. The viability of eggs and protoscolices was confirmed using 0.1% eosin staining. Vinifera leaf extract exhibited the decisive sporicidal effect at 100%, 91%, 60%, and 41% after 30 min at concentrations of 50, 30, 10, and 5 mg/mL, and in eggs at 11% and 19% after 24 and 48 h at a concentration of 200 mg/mL, respectively. Increased incubation times and higher dosages often increase mortality. The results exhibited that V. vinifera is effective. This study confirmed that grape leaf extract has high sporicidal activity in vitro. However, more studies are required to determine the exact active chemical and its action mechanism and perform in vivo utilization to confirm these results.

Assessment of calcium hypochlorite for Bacillus anthracis spore surface's decontamination

Contamination with microorganisms occurs in laboratories but is also of high concern in the context of bioterrorism. Decontamination is a cornerstone that promotes good laboratory practices and occupational health and safety. Among the most resistant structures formed by microorganisms are spores, produced notably by Clostridium and Bacillus species. Here, we compared six products containing four different molecules (hydrogen peroxide, peracetic acid, sodium and calcium hypochlorite) on B. anthracis Sterne spores. We first selected the most efficient product based on its activity against spore suspensions using French and European standards. Four products showed sporicidal activity, of which only two did so in a time frame consistent with good laboratory practices. Then, we tested one of these two products under laboratory conditions on fully virulent B. anthracis spores, during common use and after contamination through a spill of a highly concentrated spore suspension. We, thus, robustly validated a decontaminant based on calcium hypochlorite not only on its ability to kill spores but also on its effectiveness under laboratory conditions. At the end, we were able to assure a complete disinfection in 1 min after spillover and in 2 min for common use.

Phytochemicals, antimicrobial, and sporicidal activities of moss, Dicranum polysetum Sw., against certain honey bee bacterial pathogens.

Beekeeping is an important agricultural and commercial activity globally practiced. Honey bee is attacked by certain infectious pathogens. Most important brood diseases are bacterial including American Foulbrood (AFB), caused by Paenibacillus larvae (P. larvae), and European Foulbrood (EFB) by Melissococcus plutonius (M. plutonius) in addition of secondary invaders, e.g. Paenibacillus alvei (P. alvei) and Paenibacillus dendritiformis (P. dendritiformis). These bacteria cause the death of larvae in honey bee colonies. In this work, antibacterial activities of extracts, fractions, and isolated certain compounds (nominated 1-3) all originated from moss, Dicranum polysetum Sw. ( D. polysetum), were tested against some honey bee bacterial pathogens. Minimum inhibitory concentration, minimum bactericidal concentration, and sporicidal values ​​of methanol extract, ethyl acetate, and n-hexane fractions ranged between 10.4 and 18.98, 83.4-303.75 & 5.86-18.98µg/mL against P. larvae, respectively. Antimicrobial activities of the ethyl acetate sub-fractions (fraction) and the isolated compounds (1-3) were tested against AFB- and EFB-causing bacteria. Bio-guided chromatographic separation of ethyl acetate fraction, a crude methanolic extract obtained from aerial parts of D. polysetum resulted in three natural compounds: a novel one, i.e. glycer-2-yl hexadeca-4-yne-7Z,10Z,13Z-trienoate (1, dicrapolysetoate; given as trivial name), in addition to two known triterpenoids poriferasterol (2), and γ-taraxasterol (3). Minimum inhibitory concentration ranges were 1.4-60.75, 8.12-65.0, 2.09-33.44 & 1.8-28.75µg/mL for sub-fractions, compounds 1, 2, and 3, respectively.

ЭФФЕКТИВНОСТЬ ДЕЗИНФЕКТАНТОВ НА ОСНОВЕ АКТИВНОГО КИСЛОРОДА ПРИ АМЕРИКАНСКОМ ГНИЛЬЦЕ ПЧЕЛ

Disinfection is the most important element in the complex of veterinary and sanitary measures for american foulbrood of bee. The use of peroxide preparations as disinfectants: Oxygran and Dezinbak super, as well as ozone gas with increased bactericidal and sporicidal activity, having a short exposure time and the ability to decompose to water and oxygen, is one of the stages of obtaining environmentally friendly commercial beekeeping products.

Survival of Clostridioides difficile spores in thermal and chemo-thermal laundering processes and influence of the exosporium on their adherence to cotton bed sheets.

Clostridioides difficile spores were previously demonstrated to survive industrial laundering. Understanding interactions between heat, disinfectants and soiling (e.g. bodily fluids) affecting C. difficile spore survival could inform the optimization of healthcare laundry processes. Reducing spore attachment to linen could also enhance laundering efficacy. This study aimed to compare the sensitivity of C. difficile spores to heat and detergent, with and without soiling and to investigate adherence to cotton. Survival of C. difficile spores exposed to industrial laundering temperatures (71-90°C), reference detergent and industrial detergent was quantified with and without soiling. The adherence to cotton after 0 and 24 h air drying was determined with the exosporium of C. difficile spores partially or fully removed. Clostridioides difficile spores were stable at 71°C for 20 min (≤0·37 log10 reduction) while 90°C was sporicidal (3 log10 reduction); soiling exerted a protective effect. Industrial detergent was more effective at 71°C compared to 25°C (2·81 vs 0·84 log10 reductions), however, specifications for sporicidal activity (>3 log10 reduction) were not met. Clostridioides difficile spores increasingly adhered to cotton over time, with 49% adherence after 24 h. Removal of the exosporium increased adherence by 19-23% compared to untreated spores. Further understanding of the role of the exosporium in attachment to cotton could enhance spore removal and aid decontamination of linen.

Direct Observation of the Sporicidal Action of Hydrogen Peroxide on Bacillus atrophaeus Spores By Optical Trapping Raman Microscopy

Hydrogen peroxide (H2O2), a strong oxidizer, is frequently used for chemical sterilization in aseptic food processing. Due to their inherent robustness, bacterial spores, i.e. spores of Bacillus atrophaeus, are commonly employed to evaluate the efficacy of the sterilization procedure [1]. Despite its widespread use, however, the details of the sporicidal action of H2O2 are not yet fully understood, with various mechanisms being discussed in the literature [2,3]. Here, we employ optical trapping Raman microscopy to elucidate the sporicidal mechanism of H2O2. Optical trapping Raman microscopy allows us to isolate, investigate, and manipulate individual spores from a sample (Fig. 1A). Combining optical microscopy with the real-time, label-free chemical information obtained from Raman spectroscopy directly reveals the sequence of steps that lead to oxidative spore death after H2O2 exposure (Fig. 1B).We find that spore degradation begins with the fast, cooperative release of dipicolinic acid (DPA), a key spore biomarker and a major component of spore’s core. This indicates a breach of the inner membrane surrounding the core. The onset of DPA release depends on the concentration of H2O2. DPA outflux is accompanied by the formation of oxidation products (mostly carbonyl compounds) and oxidation continues after exchange of DPA with the surrounding medium is complete. The remaining spore shell then slowly disintegrates and continues to shrink on a timescale of hundreds of seconds. Simultaneous observation of spore morphology and size by optical microscopy and particle tracking corroborates this three-step mechanism.The presented assay allows on-line monitoring of spore composition and morphology, which directly reveals the mechanism underlying the sporicidal action of H2O2. In addition, trapped spores can be exposed to different chemical or physical stimuli (temperature, light, chemical composition of the surrounding medium, etc.) to investigate a variety of industrially relevant sterilization conditions. Jildeh, Z. B., Wagner, P. H. & Schöning, M. J. Sterilization of Objects, Products, and Packaging Surfaces and Their Characterization in Different Fields of Industry: The Status in 2020. physica status solidi (a) 218, 2000732 (2021). Setlow, P. & Christie, G. What’s new and notable in bacterial spore killing. World J Microbiol Biotechnol 37, 144 (2021). Setlow, P. Spores of Bacillus subtilis: their resistance to and killing by radiation, heat and chemicals. J Appl Microbiol 101, 514-525 (2006). Figure 1

Susceptibility of Clostridium sporogenes Spores to Selected Reference Substances and Disinfectants.

Research on the susceptibility of the spores of anaerobic bacteria such as Clostridium sporogenes or Clostridioides difficile is vital for assessing the sporicidal activity of disinfectants. The diverse susceptibility of anaerobic bacteria spores may lead to different disinfection parameters being determined by laboratories that prepare spore suspensions to test sporicidal effectiveness. The tests were performed using the suspension method according to PN-EN 13704:2018-09. In order to assess the susceptibility of the C. sporogenes spores, the criterion established for the C. difficile ribotype 027 spores was used in accordance with PN‑EN 17126:2019-01. The susceptibility of the C. sporogenes spores to glutardialdehyde corresponded to the susceptibility ranges established for the C. difficile ribotype 027 spores. The C. sporogenes spore suspension was susceptible to low concentrations of peracetic acid (0.01%). A disinfectant containing peracetic acid as the active substance showed high sporicidal activity at a low concentration (1%), a short contact time (15 minutes), and a high organic load (3.0 g/l bovine albumin + 3.0 ml/l sheep erythrocytes), as compared to a disinfectant with glutardialdehyde, which was sporicidal at a higher concentration (2.5%), at a longer contact time (60 minutes) and lower organic conditions (3.0 g/l bovine albumin). There is a need to define the minimum susceptibility criteria for the C. sporogenes spores to the reference substances most often found in disinfectants with sporicidal activity. Excessive susceptibility of the C. sporogenes spores to reference substances may result in low-performance parameters of disinfection products with sporicidal activity and lead to ineffective disinfection in practice.

Sporicidal Action of Pulsed Radiation of Hot Plasma.

In the study, we used a Pilimin IR-10 spark discharge generator as a source of pulsed radiation of hot plasma; a corona discharge generator - as a source of cold plasma; a DKB-9 low-pressure mercury lamp - as a source of continuous radiation of UV band, wavelength of 253.7 nm. The samples were processed in Petri dishes, 40 mm in diameter, their volume being 4 and 10 cm3. The study used an L-tyrosine solution in distilled water (the concentration: 160 mg/L), a suspension of bacteria and spores of micromycetes (its concentration being ~106 cells per 1 ml). Tyrosine conversion products were identified spectrophotometrically before and after treatment. The biocidal and sporicidal effects were assessed by counting CFU (colony-forming units) after seeding incubation at 27-37°C. The oxidation of tyrosine by HO2• radicals was found to be impossible. Under 2 the action of nitrogen compounds, nitration proceeds with 3-nitrotyrosine formation. The nitration reaction is slow, taking about 100 h. A possible nitration mechanism is through the formation of the nitronium ion NO2+ in an acidic medium.The biocidal effect of hot plasma radiation turned out to be weaker than that of UV radiation of a DKB-9 lamp. This is due to the difference in their emission spectrum. The sporicidal effect of hot plasma radiation was more pronounced: a 10-fold decrease in the number of CFU was observed at radiation doses of 200-280 J. Under the action of UV radiation, at the same doses, the decrease in the number of CFU was from 3 to ~30%. The sporicidal effect of hot plasma radiation is due to the decay of a long-living …ONOOH/ONOO-… complex with the formation of a nitric oxide and a nitronium ion in an acidic medium. The study showed the viability of spores under the action of pulsed radiation of hot plasma to decrease. While the light radiation of a UV lamp, under studied conditions, slightly penetrates the protective coating of a spore. The sporicidal effect of hot plasma radiation is due to the decay of a long-living …ONOOH/ONOO-… complex with the formation of a nitric oxide and a nitronium ion in an acidic medium. Nitration plays a decisive role in the sporicidal action of the hot plasma radiation of a spark discharge. The principle of the sporicidal effect of gas-discharge plasma radiation can be used to develop disinfecting devices.

Biological Activity and Phytochemical Analysis of Dicranum scoparium against the Bacterial Disease for Honey Bee

Bacterial diseases, such as American Foulbrood (AFB) and European Foulbrood (EFB), are known to have catastrophic effects on honey bees (if left to spread, can wipe out entire colonies), leading to severe financial losses in the beekeeping industry. The aim of this study was to evaluate the pharmacological properties of methanol extract and its fractions (ethyl acetate, hexane, water) derived from Dicranum scoparium Hedw., which could be utilized as a potential drug to prevent the bacterial diseases (AFB and EFB) affecting the honey bees. For this purpose, crude methanol extract and ethyl acetate/hexane/water fractions were prepared from the aerial part of D. scoparium, collected from Trabzon province. Bio-guided fractionation of the extract and its fractions led to the first-time isolation of five compounds. The structure of all compounds was elucidated by nuclear magnetic resonance (NMR) spectroscopy, ultraviolet (UV) spectral analysis, Fourier-transform infrared spectroscopy (FT-IR), liquid chromatography quadrupole time-of-flight mass spectroscopy (LC-QToF-MS), and by comparison of their NMR data with that of literature. The analysis of these compounds revealed significant antibacterial and sporicidal activities against bacteria causing larval diseases in honey bees. The antibacterial activity of these compounds ranged from 0.6 to 60 μg/mL against AFB and EFB causing bacteria. Therefore, the natural raw extract and fractions of D. scoparium could be used as potential therapeutic agents against bacterial agents affecting honey bees.

Optimization of sporulation and purification methods for sporicidal efficacy assessment on Bacillus spores.

Validating the efficacy of sporicidal agents is a critical step in current good manufacturing practices for disinfection requirements. A limitation is that the poor quality of spores can lead to false positive sporicidal results. The aim of this study was to explore optimal sporulation and purification methods in Bacillus spores. Spores of 7 Bacillus strains were produced in 5 different sporulation media. After density centrifugation, spore yields were measured by phase-contrast microscopy and enumeration assays. Effects of purification methods including heat, sonication and lysozyme, and maturation on spore qualities were determined by sodium hypochlorite sporicidal assay. Difco sporulation media was identified as the preferred sporulation medium for 4 out of 7 tested Bacillus strains. Sporulation rates in B. cereus, B. sphaericus, and B. thuringiensis were higher at 30°C than the rates at 37°C at a difference of 5%, 65%, and 20%, respectively. Bacillus licheniformis favored Mn2+-amended 10% Columbia Broth at 37°C for sporulation with 40-72% higher sporulation rates than other media. The maximum sporulation rates of B. cereus and B. thuringiensis were observed on double-strength Schaeffer's-glucose broth. All studied purification methods improved the spore purity with strain variations. However, intense heat (80°C for 20min) and lysozyme (100μg/mL) treatment impaired the spore quality of specific Bacillus strains by sensitizing them against sodium hypochlorite. The length of the maturation period had an impact on the spore resistance, and the most optimal maturation periods ranged from 7 to 21 days in Bacillus strains. The results of this study will pave the way for further evaluation of the sporicidal activity of disinfectants.

The sporicidal activity of a disinfectant with peracetic acid against the spores of Bacillus subtilis and Bacillus cereus according to the european standard PN-EN 17126: 2019-01.

The assessment of the sporicidal effectiveness of disinfectants is important from the point of view of the prevention of nosocomial infections and spore contamination of clinical samples, medical equipment and materials used in patient care. The rods of Bacillus spp. cause infections of the digestive system, bloodstream and, less often, respiratory tract. Cases were diagnosed in immunocompromised patients, malignant neoplasms and in neonatal wards. The source of the infection was hospital linen, reusable towels, catheters or milk from the human milk bank. Determination of the minimal sporicidal parameters of a disinfectant containing peracetic acid. The sporicidal activity of a disinfectant containing peracetic acid against Bacillus subtilis and Bacillus cereus spore suspensions was tested in a defined concentration range during a contact time of 15 minutes, in the presence of various interfering substances (clean and dirty conditions) according to the European Standard PN-EN 17126: 2019-01. The disinfecting preparation containing peracetic acid showed sporicidal activity against Bacillus subtilis at a concentration of 1% for 15 minutes under clean and dirty conditions and at concentrations of 0.5%, 1.00% and 1.25% against the Bacillus cereus spores during the same contact time but only under dirty conditions. The preparation showed no sporicidal activity against Bacillus cereus at concentrations of 2%, 3%, 4% and 5% during a contact time of 15 minutes under both dirty and clean conditions. In areas where there is a risk of infecting a patient or contaminating clinical specimens, materials and equipment with spores of Bacillus spp., it is necessary to use disinfectants with sporicidal activity confirmed according to the PN-EN 17126: 2019-01 standard. The sporicidal activity of disinfectants containing peracetic acid may depend on the method of preparing the solutions, their concentration, pH, temperature and the contamination degree of the disinfected surface.

Virucidal, bactericidal, and sporicidal multilevel antimicrobial HEPA-ClO2 filter for air disinfection in a palliative care facility

• HEPA-ClO 2 with contact-killing and release-killing properties against microbes. • HEPA-ClO 2 with effective in filtering and killing viruses, bacteria, and spores. • HEPA-ClO 2 is safe according to in-vitro and in-vivo studies. • HEPA-ClO 2 is more efficient than unmodified HEPA in field trial and CFD studies. Pathogenic microbes in the air are the leading cause of respiratory diseases and illnesses, and respiratory viruses are responsible for some of the world’s most devastating epidemics and pandemics. Therefore, their capture, removal, and disinfection are essential in preventing the spread of diseases. A multilevel antimicrobial HEPA-ClO 2 prepared by coating micro-encapsulated chlorine dioxide on high-efficiency particulate air (HEPA-H13) filter, displays broad-spectrum virucidal and bactericidal, as well as sporicidal activities through the combined “contact-killing” and “release-killing” properties. In-vitro cytotoxicity (i.e., human A549 cells) and in-vivo inhalation toxicity tests (i.e., Kunming mice) indicate HEPA-ClO 2 has low inhalation toxicity and is safe. Furthermore, it has superb performance against a panel of infectious respiratory viruses (e.g., influenza viruses, EV-71) and bacteria (e.g., L. pneumophila , K. pneumonia ) and drug-resistant organisms (e.g., MRSA, MRPA), attaining log 2 reduction (99%) within a minute. However, spores required 30 min to reach 99% inactivation. A 260-day field trial study at a palliative care facility demonstrated that air purifiers could significantly decrease airborne particulates and microbes (bacteria and mold/fungi) and confirmed the long-term efficacy of the HEPA-ClO 2 filters and their superiority over uncoated HEPA-H13 against microbes. The experimental results from the wardroom were validated by a computational fluid dynamics (CFD) simulation.