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Enhancement of the bactericidal efficacy of N-chlorotaurine by inflammation samples and selected N-H compounds
Abstract
The influence of organic matter on the antibacterial activity of the endogenous substance N-chlorotaurine was examined. In contrast to other active N-chlorine compounds (e.g. hypochlorite, chloramine T) the efficacy of N-chlorotaurine was enhanced in the presence of the amine compounds α- and β-alanine, glycine and especially ammonium chloride. This remarkable effect was found to result from an equilibration between N-chlorotaurine and the amino acids, resp. ammonium, and formation of the corresponding N-chlorine derivatives by transhalogenation. In human exudates, too, the efficacy of N-chlorotaurine increased, which can be explained by an over-compensation of consumption effects by generation of these highly bactericidal N-chlorine derivatives. Moreover, repeated treatment at sublethal doses did not cause a decrease in efficacy of N-chlorotaurine. This suggests that application of N-chlorotaurine for local treatment of topical infections will be successful.
... Its antimicrobial properties turned out to be broad-spectrum as it is typical for active chlorine antiseptics [23]. Studies disclosed broad-spectrum bactericidal (Gram-positive and Gram-negative bacteria) [24][25][26][27][28][29][30], fungicidal (yeasts and molds) [27,[31][32][33], and virucidal activity (herpes simplex, adenoviruses, HIV, influenza so far, [34][35][36][37]) of millimolar NCT, and protozoocidal activity against amoebae, leishmaniae, and trichomonads [38][39][40]. Because of the unspecific oxidative mechanism of action, development of resistance is extremely improbable and was actually not detected in laboratory tests [27]. ...
... Its antimicrobial properties turned out to be broad-spectrum as it is typical for active chlorine antiseptics [23]. Studies disclosed broad-spectrum bactericidal (Gram-positive and Gram-negative bacteria) [24][25][26][27][28][29][30], fungicidal (yeasts and molds) [27,[31][32][33], and virucidal activity (herpes simplex, adenoviruses, HIV, influenza so far, [34][35][36][37]) of millimolar NCT, and protozoocidal activity against amoebae, leishmaniae, and trichomonads [38][39][40]. Because of the unspecific oxidative mechanism of action, development of resistance is extremely improbable and was actually not detected in laboratory tests [27]. ...
... Studies disclosed broad-spectrum bactericidal (Gram-positive and Gram-negative bacteria) [24][25][26][27][28][29][30], fungicidal (yeasts and molds) [27,[31][32][33], and virucidal activity (herpes simplex, adenoviruses, HIV, influenza so far, [34][35][36][37]) of millimolar NCT, and protozoocidal activity against amoebae, leishmaniae, and trichomonads [38][39][40]. Because of the unspecific oxidative mechanism of action, development of resistance is extremely improbable and was actually not detected in laboratory tests [27]. ...
N-Chlorotaurine (NCT) is a mild long-lived oxidant that can be applied to sensitive body regions as an endogenous antiseptic. Enhancement of its microbicidal activity in the presence of proteinaceous material because of transchlorination, a postantibiotic/postantifungal effect and antitoxic activity renders it interesting for treatment of fungal infections, too. This is confirmed by first case applications in skin and mucous membranes of different body sites. Recent findings of good tolerability of inhaled NCT suggest further investigations of this substance for treatment of bronchopulmonary diseases, where microorganisms play a role, particularly multi-resistant ones. The availability of a well-tolerated and effective inhaled antiseptic with anti-inflammatory properties could be a significant progress, in particular for chronic pulmonary diseases, such as chronic obstructive pulmonary disease or cystic fibrosis.
... As an active chlorine compound, it is microbicidal against bacteria, fungi, viruses, and protozoa, and it does not induce resistance because of the multiple target molecules in pathogens (18,24). This has been confirmed for NCT and its analogue dichloro-dimethyltaurine in multiple-passage studies with bacteria (25,26). NCT is effective against bacteria in biofilms, too (27)(28)(29). ...
... The bactericidal and fungicidal activity of NCT in a medium representative for the viscous mucus of CF patients has been proven in this study. Similar to other organic materials (26,44,48), the activity in ASM was even stronger than in buffer solution without chlorine consuming molecules (41,42,44,45). This effect was particularly remarkable with fungi, leading to an approximately 50 times more rapid killing. ...
... In the first view surprising, an easy explanation can be given. The active chlorine atom of NCT is not only reduced and inactivated in the presence of organic material, it is partly also transferred to amino groups of the organic material, thereby forming the corresponding chloramines in equilibrium (20,26,44,49). Particularly the transhalogenation from NCT to ammonium, which forms the more lipophilic, better penetrating and stronger microbicidal monochloramine (NH 2 Cl), has been considered as causative (22,50). ...
Lung infections with multiresistant pathogens are a major problem of patients suffering from cystic fibrosis (CF). N-chlorotaurine (NCT), a microbicidal active chlorine compound with no resistance development, is well tolerated upon inhalation. The aim of this study was to investigate NCT on its bactericidal and fungicidal activity in vitro in artificial sputum medium (ASM) mimicking the composition of cystic fibrosis mucus.
The medium was inoculated with bacteria ( Staphylococcus aureus including some MRSA strains, Pseudomonas aeruginosa , Escherichia coli ) or spores of fungi ( Aspergillus fumigatus , Aspergillus terreus , Candida albicans , Scedosporium apiospermum , Scedosporium boydii , Lomentospora prolificans , Scedosporium aurantiacum , Scedosporium minutisporum , Exophiala dermatitidis , Geotrichum sp. ) to final concentrations of 10 ⁷ -10 ⁸ CFU/ml. NCT was added at 37°C, and time-kill assays were performed.
At a concentration of 1% (10 mg/ml, 55 mM) NCT, bacteria and spores were killed within 10 min and 15 min to the detection limit of 10 ² CFU/ml (reduction by 5-6 log 10 ). A reduction by 2 log 10 was still achieved by 0.1% (bacteria) and 0.3% NCT (fungi), largely within 10-30 min. Measurements by means of iodometric titration showed oxidizing activity over 1, 30, 60, and >60 min at a concentration of 0.1%, 0.3 %, 0.5%, and 1.0 % NCT, respectively, which matches the killing tests.
NCT demonstrated broad-spectrum microbicidal activity in the milieu of CF mucus at concentrations ideal for clinical use. Microbicidal activity of NCT in ASM was even stronger than in buffer solution, particularly pronounced with fungi. This can be explained largely by formation of monochloramine by transhalogenation, which rapidly penetrates pathogens.
... Fungicidal activity has already been shown against other fungi (yeasts and molds [19][20][21]) without drug re-sistance, in contrast to the case with antifungals (22). Particularly for skin lesions, the addition of ammonium chloride (NH 4 Cl) with a formulation of monochloramine (NH 2 Cl), which kills fungi within minutes, has to be considered (21,23). ...
... The remarkable enhancement of the killing of molds (and of bacteria and protozoa) by the addition of NH 4 Cl to NCT known from previous studies (21,23,36) was also confirmed to a similar extent against Scedosporium. Due to the more rapid killing of microorganisms in body fluids and exudates, and due to the successful therapeutic application of NCT in humans and animals (14,15,21,23,37,38), we are convinced that this effect plays a role in vivo. ...
... The remarkable enhancement of the killing of molds (and of bacteria and protozoa) by the addition of NH 4 Cl to NCT known from previous studies (21,23,36) was also confirmed to a similar extent against Scedosporium. Due to the more rapid killing of microorganisms in body fluids and exudates, and due to the successful therapeutic application of NCT in humans and animals (14,15,21,23,37,38), we are convinced that this effect plays a role in vivo. It is explained by the formation of monochloramine (NH 2 Cl) in equilibrium with NCT (36,39). ...
N-chlorotaurine (NCT), a well-tolerated endogenous long-lived oxidant that can be applied topically as antiseptic, was tested on its fungicidal activity against Scedosporium and Lomentospora, opportunistic fungi that cause severe infections with limited treatment options mainly in immunocompromised patients.In quantitative killing assays, both hyphae and conidia of Scedosporium apiospermum, Scedosporium boydii, and Lomentospora prolificans (former Scedosporium prolificans) were killed by 55 mM (1.0%) NCT at pH 7.1 and 37 °C with a log10 reduction in CFU of 1 - 4 after 4 h and of 4 to > 6 after 24 h. Addition of ammonium chloride to NCT markedly increased this activity. LIVE/DEAD staining of conidia treated with 1.0% NCT for 0.5 to 3 h disclosed increased permeability of the cell wall and membrane. Pre-incubation of the test fungi in 1.0% NCT for 10 - 60 min delayed the time to germination of conidia by 2 h - >12 h and reduced their germination rate by 10.0 - 100.0%. Larvae of Galleria mellonella infected with 1.0 × 10E7 conidia of S. apiospermum and S. boydii died at a rate of 90.0 - 100% after 8-12 days. The mortality rate was reduced to 20 - 50.0% if conidia were pre-incubated in 1.0% NCT for 0.5 h or if heat-inactivated conidia were used.Our study demonstrates fungicidal activity of NCT against different Scedosporium and Lomentospora species. A postantifungal effect connected with loss of virulence occurs after sublethal incubation times. The augmenting effect of ammonium chloride can be explained by formation of monochloramine.
Copyright © 2015, American Society for Microbiology. All Rights Reserved.
... NCT, the N-chloro derivative of the amino acid taurine produced by granulocytes and monocytes during the oxidative burst, is a longlived oxidant that can be synthesised chemically [6] and applied topically for treatment of infections [7]. It has broad-spectrum microbicidal activity against bacteria, viruses, fungi and protozoa [5,[7][8][9]. Phase I and II clinical studies have revealed high tolerability and therapeutic effects of regular applications of 55 mM (1%) NCT in the eye, sinuses, oral cavity, outer ear canal, skin ulcerations and urinary bladder [7,10]. ...
... The antimicrobial activity of NCT against bacteria [8], fungi [8,9] and free-living amoebae [5] can be enhanced markedly by * Corresponding author. Tel.: +43 1 40490 79446; fax: +43 1 40490 79435. ...
... The antimicrobial activity of NCT against bacteria [8], fungi [8,9] and free-living amoebae [5] can be enhanced markedly by * Corresponding author. Tel.: +43 1 40490 79446; fax: +43 1 40490 79435. ...
Trichomoniasis, caused by the protozoan Trichomonas vaginalis, is usually treated with metronidazole, however resistance is on the rise. In this study, N-chlorotaurine (NCT), a new endogenous mild active chlorine compound for topical use, killed T. vaginalis in vitro within 15 min of treatment at a concentration of 55 mM (1%), which is well tolerated by human tissue. The activity of NCT was further enhanced by addition of ammonium chloride (NH 4 Cl). A combination of 5.5 mM (0.1%) NCT plus 19 mM (0.1%) NH 4 Cl killed 100% of trichomonads within 5 min.
... Marcinkiewicz et al. 1995;Walczewska et al. 2017). Therefore, endogenous NCT and NBT are important components of innate immunity and the non-specific host defence system (Marcinkiewicz et al. 1995 Nagl andGottardi 1996;Jang JS et al. 2009) Moreover, NCT can regulate the course of acute inflammation (Park et al. 1997;Marcinkiewicz et al. 1995) and has a great impact on the fate of neutrophils (Kim and Cha 2014). ...
... This was confirmed in in vitro experiments when the combination of NCT and NH4Cl was used in antifungal susceptibility testing. The enhanced antifungal effect and the reduction in the incubation time required to kill fungi was noted (Nagl and Gottardi 1996;Nagl et al. 2001;Reeves et al. 2006;Lackner et al. 2015). Similar results indicating better antifungal activity in the presence of organic compounds were obtained by Gruber et al. who studied NCT against Aspergillus fumigatus, Aspergillus terreus, Candida albicans, Exophiala dermatitidis, Geotrichum sp., Lomentospora prolificans, Scedosporium apiospermum, Scedosporium aurantiacum, Scedosporium boydii, Scedosporium minutisporum in artificial sputum medium (ASM), mimicking the composition of mucus of cystic fibrosis patients (Gruber et al. 2017). ...
Taurine haloamines, N-chlorotaurine (NCT, TauCl), and N-bromotaurine (NBT, TauBr) are formed by a reaction between taurine and hypohalous acids, HOCl and HOBr, respectively. The major source of endogenous taurine haloamines is neutrophils. Both NCT and NBT share strong anti-inflammatory and microbicidal activities supported by an absence of microbial resistance. In the light of these properties, a number of clinical studies have been performed to document their effectiveness in treatment of bacterial, fungal, and viral infections. The administration of NCT and NBT has been limited to topical application, as they are decomposed upon systemic delivery. This review summarizes current knowledge concerning the therapeutic use of NCT and NBT mainly in various skin disorders such as non-healing wounds, acne vulgaris, herpes zoster, and psoriasis. Moreover, the beneficial effect of NCT inhalation in early stages of COVID-19 and other viral respiratory infections is discussed. And finally, we would like to suggest that NCT might be used to inhibit the development of the cytokine storm through its capacity to suppress the production of IL-6.
... These times required for inactivation of biofilms by NCT in vitro may appear as relatively long for successful application in vivo. In this regard, however, it is important that the microbicidal activity of NCT is not decreased but increased in the presence of human body fluids and exudates [11,15,[33][34][35]. The reason is the transfer of the active chlorine of NCT to other amino compounds and the formation of corresponding chloramines in equilibrium (transchlorination) [36]. ...
... The reason is the transfer of the active chlorine of NCT to other amino compounds and the formation of corresponding chloramines in equilibrium (transchlorination) [36]. Some of them are more lipophilic than NCT, particularly monochloramine (NH 2 Cl), and penetrate and kill microorganisms faster [11,15,[33][34][35]. The efficacy of NCT in chronic wound infections may also indicate that transchlorination plays a significant role in the attack of biofilms by NCT [19,27,28]. ...
Background: N-chlorotaurine (NCT), an antiseptic that originates from the human defense system, has broad-spectrum microbicidal activity and is well tolerated by human tissue and applicable to sensitive body regions. Bacteria in short-term biofilms, too, have been shown to be killed by NCT. It was the aim of the present study to demonstrate the activity of NCT against bacteria and yeasts in longer-lasting biofilms, including their co-culture. Materials and methods: Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella variicola biofilms were grown for 14 weeks in MBECTM inoculator with 96 well base. Some pegs were pinched off weekly and incubated in 1% NCT in PBS (PBS only for controls) at pH 7.1 and 37 °C, for 30 and 60 min. Subsequently, bacteria were resuspended by ultrasonication and subjected to quantitative cultures. Similar tests were conducted with C. albicans biofilms grown on metal (A2-steel) discs for 4 weeks. Mixed co-cultures of C. albicans plus each of the three bacterial strains on metal discs were grown for 5–7 weeks and weekly evaluated, as mentioned above. Results: Single biofilms of S. aureus, P. aeruginosa, and K. variicola grew to approximately 1 × 10⁶ colony forming units (CFU)/mL and C. albicans to 1 × 10⁵ CFU/mL. In combined biofilms, the CFU count was about 1 log10 lower. Viable counts of biofilms of single bacteria were reduced by 2.8 to 5.6 log10 in 1% NCT after 60 min (0.9 to 4.7 log10 after 30 min) with Gram-negative bacteria being more susceptible than S. aureus. Significant reduction of C. albicans by 2.0 to 2.9 log10 occurred after 4 h incubation. In combined biofilms, viable counts of C. albicans were reduced by 1.1 to 2.4 log10 after 4 h, while they reached the detection limit after 1 to 2 h with bacteria (2.0 to > 3.5 log10 reduction). Remarkably, older biofilms demonstrated no increase in resistance but constant susceptibility to NCT. This was valid for all tested pathogens. In electron microscopy, morphological differences between NCT-treated and non-treated biofilms could be found. Conclusions: NCT is active against long-term biofilms of up to several months irrespective of their age. Combined biofilm cultures of yeasts and bacteria show a similar susceptibility pattern to NCT as single ones. These results contribute to the explanation of the clinical efficacy of NCT, for instance, in infected chronic wounds and purulently coated crural ulcerations.
... However, because of its mild activity and high tolerability, NCT can be applied therapeutically in 1000fold higher concentration (55 mmol l À1 ) than the natural one (about 20-50 µmol l À1 , (Grisham et al. 1984)). In this range, even repeated exposure to NCT and other chloramines does not induce resistance (Nagl and Gottardi 1996;D'Lima et al. 2012). ...
Aims:
N-chlorotaurine is a body-own mild oxidizing antiseptic that can be applied topically as a well-tolerated anti-infective at many body sites. The objective of this study was to demonstrate its activity against representative nosocomial multidrug-resistant bacteria.
Methods and results:
The bactericidal activity of N-chlorotaurine was tested in quantitative killing assays against a panel of multiresistant Gram-positive and Gram-negative clinical isolates. N-chlorotaurine (1%, 55 mmol l-1 ) reduced the number of CFU of strains of methicillin-resistant Staphylococcus aureus, linezolid-resistant Staphylococcus epidermidis, vancomycin-resistant, and linezolid- and vancomycin-resistant Enterococcus faecium, 3MRGN and 4MRGN Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae by at least 2 log10 steps after 15 min and completely or nearly to the detection limit after 30 min at pH 7.1 and 37°C.
Conclusion:
The activity of N-chlorotaurine against these clinical isolates is similar to that against non-resistant ATCC strains and therefore not influenced by antibiotic resistance. This can be explained by the oxidizing and chlorinating mechanism of action of N-chlorotaurine, which leads to an attack of multiple targets in the microorganisms.
Significance and impact of study:
The bactericidal spectrum of N-chlorotaurine is not restricted by resistance against antibiotics. Therefore, it can be used against resistant strains, too.
... Three modes are possible: the bromine compound kills faster (no or only little burden) or slower (medium burden) than the chlorine one, or it does not kill at all (high burden, bromine completely depleted), while the chlorine partner is not consumed completely and therefore still killing. Long-term activity: For understanding this feature, one has to distinguish between the original agent and secondary products modified with oxidizing nitrogen-halogen bonds, which emerge from the transhalogenation reactions according to eqn 1 and whose BA is known to be significantly weaker than the original agents of low molecular weight (Thomas et al. 1986;Nagl and Gottardi 1996;. Accordingly, killing curves in the presence of proteinaceous material often present a biphasic shape: after a very fast initial decrease in CFU, an extremely slow one follows (see Figs 11 and 12). ...
Aims:
To investigate and compare the bactericidal activity (BA) of active bromine and chlorine compounds in the absence and presence of protein load.
Methods and results:
Quantitative killing tests against Escherichia coli and Staphylococcus aureus were performed both in the absence and in the presence of peptone with pairs of isosteric active chlorine and bromine compounds: hypochlorous and hypobromous acid (HOCl and HOBr), dichloro- and dibromoisocyanuric acid, chlorantine and bromantine (1,3-dibromo- and 1,3 dichloro-5,5-dimethylhydantoine), chloramine T and bromamine T (N-chloro- and N-bromo-4-methylbenzenesulphonamide sodium), and N-chloro- and N-bromotaurine sodium. To classify the bactericidal activities on a quantitative basis, an empirical coefficient named specific bactericidal activity (SBA), founded on the parameters of killing curves, was defined: SBA= mean log reductions/(mean exposure times x concentration) [mmol 1(-1) min (-1)]. In the absence of peptone, tests with washed micro-organisms revealed a throughout higher BA of bromine compounds with only slight differences between single substances. This was in contrast to chlorine compounds, whose killing times differed by a factor of more than four decimal powers. As a consequence, also the isosteric pairs showed according differences. In the presence of peptone, however, bromine compounds showed an increased loss of BA, which partly caused a reversal of efficacy within isosteric pairs.
Conclusions:
In medical practice, weakly oxidizing active chlorine compounds like chloramines have the highest potential as topical anti-infectives in the presence of proteinaceous material (mucous membranes, open wounds). Active bromine compounds, on the other hand, have their chance at insensitive body regions with low organic matter, for example skin surfaces.
Significance and impact of the study:
The expected protein load is one of the most important parameters for selection of a suited active halogen compound.
N-Chlorotaurine (NCT) plays an important role in the human defense system as a main component of long-lived oxidants, and shows bactericidal, fungicidal, and virucidal activity. Besides this role, NCT seems to act regulatory on immunocompetent cells by altering cytokine production. NCT inhibited nitric oxide, TNF-α, and prostaglandin E2 (PGE2) production in activated rodent macrophages, and suppressed superoxide anion, IL-6, and IL-8 formation in human polymorphonuclear leukocytes.In this study, the influence of NCT on the production of neopterin and the activation of the enzyme indoleamine-2,3 dioxygenase (IDO) was investigated in human peripheral blood mononuclear cells (PBMC). Both events are well established to be triggered by IFN-γ and therefore related to Th1-type immune activation. Mitogen-induced neopterin production as well as tryptophan degradation were drastically reduced upon addition of NCT. Results fit in the concept of a reduction of pro-inflammatory cytokines by this compound. In contrast to earlier results, where NCT was suggested to act primarily down-regulatory on Th2 cells, we propose also a strong suppressive effect of NCT on Th1-type immunity.
Sinonasal anti-infective irrigations have emerged as a promising therapeutic modality in the comprehensive management of chronic rhinosinusitis (CRS), particularly in the context of recalcitrant disease. The purpose of this article was to delineate the current spectrum of topical anti-infective therapies available and evaluate their role in the treatment of CRS.
A systematic literature review was performed on all studies investigating the use of topical antimicrobial solutions in the medical therapy of CRS. Anti-infective irrigations were stratified into topical antibacterial, antifungal, and additive preparations according to their composition and respective microbicidal properties.
The use of topical antibiotic irrigations has been supported by low-level studies in the treatment of refractory CRS, with optimal results achieved in patients who have undergone prior functional endoscopic sinus surgery and received culture-directed therapy. Multiple evidence-based reviews have not established any clinical benefit with the administration of topical antifungals, and their use is not currently recommended in the management of routine CRS. Topical additives including surfactants may be beneficial as adjunctive treatment for recalcitrant CRS, but additional research is needed to investigate their efficacy in comparison with other agents and establish safety profiles.
Topical anti-infective solutions are not recommended as first-line therapy for routine CRS but may be considered as a potential option for patients with refractory CRS who have failed traditional medical and surgical intervention. Additional research is necessary to determine which patient populations would derive the most benefit from each respective irrigation regimen and identify potential toxicities associated with prolonged use.
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