The resistance of bacterial biofilms to physical and chemical agents is attributed in the literature to various interconnected processes. The limitation of mass transfer alters the growth rate, and physiological changes in the bacteria in the film also appear. The present work describes an approach to determination of the mechanisms involved in the resistance of bacteria to quaternary ammonium compounds (benzalkonium chloride) according to the C-chain lengths of those compounds. For Pseudomonas aeruginosa CIP A 22, the level of resistance of the bacteria in the biofilm relative to that of planktonic bacteria increased with the C-chain length. For cells within the biofilm, the exopolysaccharide induced a characteristic increase in surface hydrophilicity. However, this hydrophilicity was eliminated by simple resuspension and washing. The sensitivity to quaternary ammonium compounds was restored to over 90%. Staphylococcus aureus CIP 53 154 had a very high level of resistance when it was in the biofilm form. A characteristic of bacteria from the biofilm was a reduction in the percent hydrophobicity, but the essential point is that this hydrophobicity was retained after the biofilm bacteria were resuspended and washed. The recovery of sensitivity was thus only partial. These results indicate that the factors involved in biofilm resistance to quaternary ammonium compounds vary according to the bacterial modifications induced by the formation of a biofilm. In the case of P. aeruginosa...
The effects of seven commercially available alkaline cleaners used in the food processing industry, 0.025 M NaOH, and 0.025 M KOH on viability of wild-type (EDL 933) and rpoS-deficient (FRIK 816-3) strains of Escherichia coli O157:H7 in logarithmic and stationary phases of growth were determined. Cells were treated at 4 or 23°C for 2, 10, or 30 min. Cleaners 2, 4, 6, and 7, which contained hypochlorite and <11% NaOH and/or KOH (pH 11.2 to 11.7), killed significantly higher numbers of cells than treatment with cleaner 3, containing sodium metasilicate (pH 11.4) and <10% KOH, and cleaner 5, containing ethylene glycol monobutyl ether (pH 10.4). There were no differences in the sensitivities of logarithmic and stationary-phase cells to the alkaline cleaners. Treatment with KOH or NaOH (pH 12.2) was not as effective as four out of seven commercial cleaners in killing E. coli O157:H7, indicating that chlorine and other cleaner components have bactericidal activity at high pH. Stationary-phase cells of strain EDL 933 that had been exposed to cleaner 7 at 4 or 23°C and strain FRIK 816-3 exposed to cleaner 7 at 23°C had significantly higher D55°C (decimal reduction time, minutes at 55°C) values than control cells or cells exposed to cleaner 5...
Biofilms are slimy aggregates of microbes that are likely responsible for many chronic infections as well as for contamination of clinical and industrial environments. Pseudomonas aeruginosa is a prevalent hospital pathogen that is well known for its ability to form biofilms that are recalcitrant to many different antimicrobial treatments. We have devised a high-throughput method for testing combinations of antimicrobials for synergistic activity against biofilms, including those formed by P. aeruginosa. This approach was used to look for changes in biofilm susceptibility to various biocides when these agents were combined with metal ions. This process identified that Cu2+ works synergistically with quaternary ammonium compounds (QACs; specifically benzalkonium chloride, cetalkonium chloride, cetylpyridinium chloride, myristalkonium chloride, and Polycide) to kill P. aeruginosa biofilms. In some cases, adding Cu2+ to QACs resulted in a 128-fold decrease in the biofilm minimum bactericidal concentration compared to that for single-agent treatments. In combination, these agents retained broad-spectrum antimicrobial activity that also eradicated biofilms of Escherichia coli, Staphylococcus aureus, Salmonella enterica serovar Cholerasuis...
Various amino acid-derived compounds, for example, Nα-Cocoyl-L-arginine ethyl ester (CAE), alkyloxyhydroxylpropylarginine, arginine cocoate, and cocoyl glycine potassium salt (Amilite), were examined for their virucidal activities against herpes simplex virus type 1 and 2 (HSV-1 and HSV-2), influenza A virus (IAV), and poliovirus type 1 (PV-1) in comparison to benzalkonium chloride (BKC) and sodium dodecylsulfate (SDS) as a cationic and anionic control detergent and also to other commercially available disinfectants. While these amino acid-derived compounds were all effective against HSV-1 and HSV-2, CAE and Amilite were the most effective. These two compounds were, however, not as effective against IAV, another enveloped virus, as against HSV. Cytotoxicity of CAE was weak; at 0.012%, only 5% of the cells were killed under the conditions, in which 100% cells were killed by either SDS or BKC. In addition to these direct virucidal effects, CAE inhibited the virus growth in the HSV-1- or PV-1-infected cells even at 0.01%. These results suggest a potential application of CAE as a therapeutic or preventive medicine against HSV superficial infection at body surface.
Hypersensitive reactions to eyedrops are a common finding in clinical practice and represent a frequent cause of discontinuation of the therapy. Moreover, experimental and clinical studies show that long term use of topical drugs may induce ocular surface changes causing discomfort and potentially negatively affecting the compliance to the treatment as well as the success rate of filtering procedures. The exact mechanism involved and the roles of the active compound and the preservatives in inducing such detrimental effects of ophthalmic solutions are unclear. During the last years several antiglaucoma agents have been marketed as either preservative-free or benzalkonium chloride-free formulations in an attempt to reduce the adverse effects related to preservatives. This paper summarizes the body of evidence from existing studies about preservatives in antiglaucoma eyedrops, focusing on the latest compounds commercially available. A systematic review of the literature was performed.
Although many disinfectants are commercially available in the veterinary field,
information on the virucidal effects of disinfectants against equine group A rotavirus
(RVA) is limited. We evaluated the performance of commercially available disinfectants
against equine RVA. Chlorine- and iodine-based disinfectants showed virucidal effects, but
these were reduced by the presence of organic matter. Glutaraldehyde had a virucidal
effect regardless of the presence of organic matter, but the effect was reduced by low
temperature or short reaction time, or both. Benzalkonium chloride had the greatest
virucidal effect among the three quaternary ammonium compounds examined, but its effect
was reduced by the presence of organic matter or by low temperature or a short reaction
time. These findings will be useful for preventing the spread of equine RVA infection.
The irritative effects of preservatives found in ophthalmologic solution, or of antiseptics used for skin disinfection is a consistent problem for the patients. The reduction of the toxic effects of these compounds is desired. Brilliant Blue G (BBG) has shown to meet the expected effect in presence of benzalkonium chloride (BAK), a well known preservative in ophthalmic solutions, and octenidine dihydrochloride (Oct), used as antiseptic in skin and wound disinfection. BBG shows a significant protective effect on human corneal epithelial (HCE) cells against BAK and Oct toxicity, increasing the cell survival up to 51 % at the highest BAK or Oct concentration tested, which is 0.01 %, both at 30 min incubation. Although BBG is described as a P2x7 receptor antagonist, other selective P2x7 receptor antagonists, OxATP (adenosine 5’-triphosphate-2’,3’-dialdehyde) and DPPH (N’-(3,5-dichloropyridin-4-yl)-3-phenylpropanehydrazide), did not reduce the cytotoxicity of neither BAK nor Oct. Therefore we assume that the protective effect of BBG is not due to its action on the P2x7 receptor. Brilliant Blue R (BBR), a dye similar to BBG, was also tested for protective effect on BAK and Oct toxicity. In presence of BAK no significant protective effect was observed. Instead...
Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas; Atualmente o uso de detergentes tem originado maior preocupação, quer a nível científico, quer a nível do ecossistema, uma vez que afetam o meio aquático na medida em que este é o destinatário final destes compostos. Foram realizados vários estudos que demonstram os efeitos nefastos que estes compostos têm a nível do compartimento aquático. Estes efeitos, podem provocar alterações nos organismos que nele habitam, como sejam alterações a nível do stress oxidativo, dano no DNA, bem como alterações bioquímicas e morfológicas nos vários tecidos e órgãos. Este trabalho teve como objetivo principal avaliar os efeitos provocados nas brânquias de Oncorhynchus mykiss (n.v. truta arco-íris) decorrentes da exposição crónica (28 dias) a diferentes concentrações de cloreto de benzalcónio. Os biomarcadores utilizados para essa avaliação foram a quantificação da atividade da enzima catalase, e avaliação de efeitos genotóxicos através do ensaio dos cometas. Os resultados obtidos para a catalase nas concentrações [0,583] e [1,050] mg/L e as concentrações [0...
Recent publications have suggested that the long term use of topical antiglaucoma medications may be detrimental to the outcome of trabeculectomy. In order to investigate this further, the effect of several adrenergic agents and a preservative on the proliferation and viability of human Tenon's capsule fibroblasts in tissue culture were examined. The following compounds were tested: adrenaline (Eppy 1% and pure adrenaline base 1%, Smith & Nephew Pharmaceuticals Ltd); dipivefrine hydrochloride (Propine 0.1% and pure dipivefrine hydrochloride 0.1% Allergan Ltd and Allergan Pharmaceuticals (Ireland) Ltd); benzalkonium chloride (pure benzalkonium chloride 0.01%, Sigma Chemical Company Ltd); the two adrenaline based preparations were also tested in the presence of an antioxidant. None of the tested compounds stimulated the proliferation of fibroblasts. The commercial products tested, their pure compounds, and the preservative all inhibited proliferation and had toxic effects on the cells. In the presence of antioxidant, commercial Eppy and pure adrenaline base appeared to have less effect on proliferation and toxicity. These findings are discussed with reference to the outcome of trabeculectomy.
We investigated the influences of various reaction conditions on equine
herpesvirus type 1 (EHV-1) disinfection by 5 commercial disinfectants (3 quaternary
ammonium compounds [QACs] and 2 chlorine-based disinfectants) and 1 anionic surfactant.
QACs at their highest recommended concentrations had no virucidal effect on EHV-1 with a
10-min reaction time at 0°C or a 1-min reaction time at room temperature. Chlorine-based
disinfectants achieved EHV-1 disinfection with a 10-min reaction time at −10°C or a 30-sec
reaction time at room temperature. In the presence of 5% fetal bovine serum, QACs (except
for benzalkonium chloride) showed more stable virucidal effects than did chlorine-based
disinfectants. The virucidal effect of the anionic surfactant was almost equivalent to
that of the QACs.