Germicidal Action Research Articles

Investigation of antifungal activities of some disinfectants on Candida albicans

Disinfectants may have fungicidal or fungistatic effects against fungal cells. The mechanism of action of disinfectants on fungal cells believed to be similar to the antibacterial activity. The aim of this study was to demonstrate the efficacy of some disinfectants against Candida albicans and to investigate the relationship between virulence and disinfectant resistance. In this study, the susceptibility of 417 clinical C.albicans and reference isolates against disinfectants were determined. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) values of disinfectants were obtained by using broth microdilution (BMD) assay. Epidemiological cut-off values (ECVs) were determined by using the MIC and MFC values. Crystal violet assay was carried out to investigate membrane permeability in disinfectant resistant and susceptible isolates. Rhodamine 6G (R6G) flourescence stain was used to show the increase in the number of efflux pumps among selected isolates. The relationship between virulence and disinfectant resistance was determined by in vitro and in vivo investigations. Virulence factors secretory acid proteinase (SAP), phospholipase, esterase, hemolytic activity and slime factor production were examined in vitro. In vivo virulence assay was performed by infecting Galleria mellonella larvae. The relationship between virulence factors and disinfectant resistance was evaluated according to the mortality rates of G.mellonella larvae. The range of MIC values for benzalkonium chloride (BZC) and chlorhexidine digluconate (CHX), triclosan (TRC) and sodium hypochlorite (SHC) were 0.25-8 mg/L, 0.06-4 mg/L and 256-16.384 mg/L, respectively. ECV values for BZC, CHX, TRC and SHC were determined as 4, 2, 1 and 4096 mg/L, respectively. The rate of crystal violet uptake was found between 26.5-57.6% for disinfectant susceptible isolates, and between 33-79.2% for resistant isolates. It is concluded that the disinfectant resistance was related with efflux pumps. Due to the lack of number of isolates that were used in this assay, the relationship between disinfectant resistance and virulence factors could not be assessed. There was no difference in the mortality of larvae infections caused by disinfectant resistant and susceptible isolates. As a result, in this study, resistant isolates against BZC, CHX, SHC and TRC were found among 417 isolates. Input and output of disinfectants were found to be associated with the cell membrane efflux pumps of C.albicans.

Determination of bacterial species present in biofilm contaminating the channels of clinical endoscopes.

Outbreaks of endoscopy-related Carbapenem-resistant Enterobacteriaceae has highlighted failures in endoscope decontamination resulting in biofilm formation. Biofilms are tolerant to detergents and disinfectants. We evaluated decontaminated endoscope channels for residual bacterial contamination and biofilm presence. 64 channels were collected from 12 gastroscopes and 11 colonoscopes. Aerobic bacteria were isolated from inside the endoscope tubing by scrapping, sonication, and aerobic plate culture. Total number of contaminating bacteria was determined by quantitative real-time PCR with 16s rRNA eubacterial universal primers. Microbial diversity was assessed using next generation DNA sequencing. Biofilm presence was visually confirmed by confocal laser scanning and scanning electron microscopy. 47% of channels were culture positive, with α-haemolytic Streptococci from gastroscopes and coliforms from colonoscopes the most frequently isolated species. Sphingomonas spp., Staphylococcus spp., Streptococcus spp., and Pseudomonas aeruginosa were also isolated. An average of 1.2×103 bacteria/cm contaminated air-water channels, 2.8×102 and 6.6×102 bacteria/cm contaminated gastroscope and colonoscope working channels, respectively. Biofilm was on all 39 channels examined and was principally composed of environmental bacteria, although all samples contained potential pathogens. Biofilm is present on many endoscope channels obtained from Australian hospitals. Any soil including biofilm can compromise disinfectant action.

Control of Brettanomyces bruxellensis on wine grapes by post-harvest treatments with electrolyzed water, ozonated water and gaseous ozone

Abstract In this study, we investigated the possible effect of electrolyzed water (EW), aqueous ozone (WO) and gaseous ozone (GO) on Brettanomyces bruxellensis DSM 7001 strain artificially inoculated on the grape surface and on its evolution during the subsequent, inoculated must fermentation. Culture-dependent and -independent techniques were used to evaluate the effectiveness of treatments against B. bruxellensis, as well as its presence during fermentation. Particularly, GO treatment of 24 h decreased its presence by about 2.1 Log, making it possible to reduce significantly the concentration of ethylphenols in the wine in relation to the control wine. EW and WO treatments caused less relevant reductions. The results showed that all the treatments reduced the presence of this yeast on grapes. However, in these experimental conditions it was not possible to achieve a complete removal of this undesirable yeast. Industrial relevance Brettanomyces spp. is considered a wine spoilage yeast due to its ability to produce off-flavors (described as Brett character) and high levels of acetic acid. Broad disinfectant action against microorganisms, eco-friendliness and easiness of on-site application are among the main advantages of the ozone and the electrolyzed water. This study demonstrated the antimicrobial potential of the EW, WO and GO treatments against B. bruxellensis inoculated on post-harvest grapes.

Quillaja saponaria Saponins with Potential to Enhance the Effectiveness of Disinfection Processes in the Beverage Industry

This study examines the in vitro effect of Quillaja saponaria extracts on Asaia spp. planktonic cells and biofilms, in comparison and combination with two disinfectants: peracetic acid and N-ethyl-N,N-dimethylhexadecylammonium bromide. The growth of six bacterial strains was evaluated spectrophotometrically. Biofilm eradication was determined using the plate count method and luminometry. The planktonic cells were characterized by relatively high resistance to peracetic acid and higher sensitivity to N-ethylo-N,N-dimethylohexadecylioamonium bromide. In almost all the tested strains, growth was inhibited by 0.125% (v/v) peracetic acid and 0.0313% (w/v) quaternary ammonium compound. However, combinations of cell pretreatment using saponin and peracetic acid action were the most efficient against both planktonic and biofilm cells. The minimum inhibitory concentrations for peracetic acid were 4–8 times lower than those for bacterial strains without preliminary saponin action. Eradication of Asaia spp. biofilms reduced the number of living cells by 4–5 logarithmic units. These results demonstrate the synergetic action of saponin extract and disinfectant, and could be useful in the development of industrial strategies against Asaia spp. biofilms.

Use of Moringa oleifera seed extracts to polish effluents from natural systems treating faecal sludge

ABSTRACTThe removal of pathogens in irrigation water is of great importance in developing countries. Indeed, wastewater generally reused for agriculture in countries such as Cameroon is associated with health and environmental concerns. Recent studies have shown a strong disinfectant action of the natural coagulant from the seeds of Moringa oleifera. These findings have raised the question whether or not they can be used to polish effluents from natural systems treating faecal sludge. This paper deals with trials carried out to investigate the effect of these extracts in reducing faecal indicators from initially treated faecal sludge leachate. Bacteriological and physico-chemical parameters were used to determine the optimum conditions and assess treatment efficacy. Settling time of 3 h at a concentration of extracts between 267 and 333 mg/L permitted to reduce Escherichia coli and faecal coliforms from 4.85 to 3.92 ulog (86.74%) and from 5.75 to 4.87 ulog (86.39%) respectively with 1 ulog equal to 90%. For the same settling time and at a concentration of 333 mg/L, faecal streptococci were removed from 6.40 to 5.67 ulog (81.33%). This level of removal suggests that this natural coagulant cannot be used alone for disinfection of heavily loaded effluent. Further investigations are therefore still needed to fulfil the Cameroon and WHO guidelines for safe reuse in agriculture.

Formation of Staphylococcus aureus Biofilm in the Presence of Sublethal Concentrations of Disinfectants Studied via a Transcriptomic Analysis Using Transcriptome Sequencing (RNA-seq).

Staphylococcus aureus is a common biofilm-forming pathogen. Low doses of disinfectants have previously been reported to promote biofilm formation and to increase virulence. The aim of this study was to use transcriptome sequencing (RNA-seq) analysis to investigate global transcriptional changes in S. aureus in response to sublethal concentrations of the commonly used food industry disinfectants ethanol (EtOH) and chloramine T (ChT) and their combination (EtOH_ChT) in order to better understand the effects of these agents on biofilm formation. Treatment with EtOH and EtOH_ChT resulted in more significantly altered expression profiles than treatment with ChT. Our results revealed that EtOH and EtOH_ChT treatments enhanced the expression of genes responsible for regulation of gene expression (sigB), cell surface factors (clfAB), adhesins (sdrDE), and capsular polysaccharides (cap8EFGL), resulting in more intact biofilm. In addition, in this study we were able to identify the pathways involved in the adaptation of S. aureus to the stress of ChT treatment. Further, EtOH suppressed the effect of ChT on gene expression when these agents were used together at sublethal concentrations. These data show that in the presence of sublethal concentrations of tested disinfectants, S. aureus cells trigger protective mechanisms and try to cope with them.IMPORTANCE So far, the effect of disinfectants is not satisfactorily explained. The presented data will allow a better understanding of the mode of disinfectant action with regard to biofilm formation and the ability of bacteria to survive the treatment. Such an understanding could contribute to the effort to eliminate possible sources of bacteria, making disinfectant application as efficient as possible. Biofilm formation plays significant role in the spread and pathogenesis of bacterial species.

Foliar Applications with Plant-Derived Extracts Control Pistachio Psyllid, <i>Agonoscena pistaciae</i>

Citrus and palm trees’ extracts, commercially formulated as ProAlexin PNSTM and AgrisprayTM, were studied against the pistachio psyllid, Agonoscena pistaciae, in field conditions. Generally, foliage spraying application against the pistachio psyllid may cause severe reduction on the honeybee forager population, which visits infested trees to collect honeydew. ProAlexinTM products have the same formulation with Provigoro 14 WA Bee Care®, a natural water acidifier, which not only has negative action on the honeybees, but also shows disinfectant action against Nosema spp. The scope of the present study was to determine any effect of ProAlexin products on the reduction of the population of the pistachio psyllid, Agonoscena pistaciae. Experiments were performed at the orchard of the A.U.A., with two mixtures sprayed on psyllid infested pistachio trees, the first with ProAlexin PNSTM and AgrisprayTM and the second only with AgrisprayTM. They were both applied with the addition of APG25TM non-ionic surfactant. Results showed that mortality on the trees treated with ProAlexin PNSTM + AgrisprayTM mixture and AgrisprayTM was significantly higher compared with the control. This could be explained due to the phytoalexins that these products elicit, which are part of the plant mechanism against insect herbivores. These products are potentially promising methods to be used in sustainable agriculture approaches against the pistachio psyllid and they should be tested for their effects on the biological control agents of this pest. Beyond this, the results of this study encourage to test their effects on other pests of pistachio and other tree species.

An integrated study on antimicrobial activity and ecotoxicity of quantum dots and quantum dots coated with the antimicrobial peptide indolicidin.

This study attempts to evaluate the antimicrobial activity and the ecotoxicity of quantum dots (QDs) alone and coated with indolicidin. To meet this objective, we tested the level of antimicrobial activity on Gram-positive and Gram-negative bacteria, and we designed an ecotoxicological battery of test systems and indicators able to detect different effects using a variety of end points. The antibacterial activity was analyzed against Staphylococcus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 1025), Escherichia coli (ATCC 11229), and Klebsiella pneumoniae (ATCC 10031), and the results showed an improved germicidal action of QDs-Ind. Toxicity studies on Daphnia magna indicated a decrease in toxicity for QDs-Ind compared to QDs alone, lack of bioluminescence inhibition on Vibrio fisheri, and no mutations in Salmonella typhimurium TA 100. The comet assay and oxidative stress experiments performed on D. magna showed a genotoxic and an oxidative damage with a dose–response trend. Indolicidin retained its activity when bound to QDs. We observed an enhanced activity for QDs-Ind. The presence of indolicidin on the surface of QDs was able to decrease its QDs toxicity.

Pathogens protection against the action of disinfectants in multispecies biofilms.

Biofilms constitute the prevalent way of life for microorganisms in both natural and man-made environments. Biofilm-dwelling cells display greater tolerance to antimicrobial agents than those that are free-living, and the mechanisms by which this occurs have been investigated extensively using single-strain axenic models. However, there is growing evidence that interspecies interactions may profoundly alter the response of the community to such toxic exposure. In this paper, we propose an overview of the studies dealing with multispecies biofilms resistance to biocides, with particular reference to the protection of pathogenic species by resident surface flora when subjected to disinfectants treatments. The mechanisms involved in such protection include interspecies signaling, interference between biocides molecules and public goods in the matrix, or the physiology and genetic plasticity associated with a structural spatial arrangement. After describing these different mechanisms, we will discuss the experimental methods available for their analysis in the context of complex multispecies biofilms.

Evaluation of the Antimicrobial Activity of a Super Oxidized Solution in Clinical Isolates.

This study evaluated the antimicrobial activity of Estericide(®) QX (super oxidized solution) in 524 bacterial clinical isolates causing nosocomial infections. The minimum inhibitory concentration (MIC) was determined by the serial broth microdilution method. The bacterial viability of the isolates and control strains was tested. The bactericidal effect of the disinfectant was determined according to the European Standards (EN) Test Methods-1040 guidelines. Assay of stability in Estericide QX after 1 year of storage was performed. The microdilution assays showed that the isolates were inhibited at concentrations of 10-40 parts per million (ppm). For gram-positive bacteria, the MIC values 20 and 40 ppm were more predominant (95%), whereas for gram-negative bacteria, the MIC values 10 and 20 ppm had the highest percentage (91.7%). The difference between the two groups was statistically significant (p<0.001). The results of the assay of bactericidal activity showed that all tested bacteria (99.999%) were killed within 30 sec of contact time. The stability test showed that Estericide QX maintained its disinfectant action over time. In conclusion, the results of the present study showed that the super oxidized solution of Estericide QX provides a high antibacterial activity on both gram-positive and gram-negative bacteria. Based on these results and under the conditions of the present study, we believe that Estericide QX can be used efficiently against multiresistant nosocomial bacteria, providing an opportunity for new disinfection alternatives.

Povidone iodine skin absorption: An ex-vivo study

Povidone iodine is a water-soluble complex used to disinfect the skin surface and it exerts prolonged germicidal action against a broad spectrum of germs. Indeed, it is often applied on burned skin, large wounds, deep tissues or mucosa. Notably some surgical hand-scrub solutions, which are considered safe antiseptics, contain large amounts of iodine that can be absorbed by skin. The aim of present study was to study the skin absorption of iodine after the application on the skin of povidone-iodine solution, used by health care workers during surgical procedure. We use Franz diffusion static cells with human skin. After 24h from the beginning of our measurement the iodine concentration in the receiving compartment was 11.59±6.3μg/cm2. The medium flux calculated was 0.73±0.33μg/cm2/h with a lag time of 8.9±1.5h. These in vitro results confirmed that povidone iodine could pass through the skin in a relevant amount that can explain the clinical findings in burned or surgically treated patients. In professional use the repetitive contact with povidone iodine, also as soap, can cause iodine skin permeation that must be considered when the washing procedures are repeated more than 20 times a day.

Ação dos desinfetantes sobre a adesão e biofilme consolidado de Staphylococcus spp.

Staphylococcus spp. são reconhecidos como importantes causadores de mastites em rebanhos leiteiros. Esses micro-organismos têm a capacidade de produzir uma estrutura denominada biofilme, que é responsável pela sobrevivência e muitas vezes pela resistência a ação de produtos desinfetantes e as demais condições adversas. Neste trabalho avaliou-se a ação de dois produtos pós-dipping a base de iodo (0,7%) e clorexidine (2,0%) sobre a adesão de Staphylococcus coagulase positiva (SCP) e Staphy-lococcus coagulase negativa (SCN) isolados de casos de mastite subclínica, e também sobre biofilmes pré formados a partir destes isolados. Os produtos testados apresentaram uma alta redução na taxa de adesão de todos os isolados. No entanto, a ação sobre os biofilmes consolidados só foi estatisticamente significativa sobre os SCN. Assim, ressalta-se a importância dos programas sanitários a fim de prevenir a formação de biofilmes e diminuir as fontes de contaminação da glândula mamaria em sistemas de produção leiteira.

Assessment of Chemical Disinfectants Efficacy against Escherichia coli Biofilm Developed on Glass and Wood at Refrigeration and Room Temperatures

Article history: Received on: 04/10/2015 Revised on: 07/11/2015 Accepted on: 26/11/2015 Available online: 27/12/2015 Objectives: The aim of this work was to study the formation of biofilm on glass and wood coupons at refrigeration and room temperatures, different incubation periods and to assess the efficacy of hydrogen peroxide (HP), Para Acetic Acid (PAA), Sodium hypochlorite (SH) and mixture of PAA + SH against the biofilm. Method: 200 μL of 10 8 suspension E. coli ATCC 29922 was inoculated on the coupons inside petri dishes containing 20 ml of tryptic soy broth, incubated at 10 and 27 0 C for 24, 48, 72 and 168 hours. Biofilm developed at each hour above was quantified by bead-vortex followed by agar plating. The action of disinfectants was tested on 168 hours biofilm. The surfaces were exposed to the disinfectants and incubated at 27 °C for 10 minutes, followed by deactivation for 5 minutes. Cells that resisted disinfectants effect were vortexed and enumerated by agar plating. Results: The results showed that E. coli can develop high biofilm on wood apart from glass. After disinfection treatment, HP had the highest efficacy at 27°C followed by PAA then SH, whilst PAA + SH had the least. Conclusion: It can be concluded that HP and PAA can be good disinfectants agents against E. coli biofilm.

Povidone-iodine toxicity in a child posted for laparoscopic removal of hepatic and renal hydatid cysts.

Sir, Povidone-iodine (PI) is an antiseptic solution consisting of polyvinylpyrrolidone with water and iodine (available iodine 1%). The 10% solution has been used effectively as a scolicidal agent for hydatid cysts. We hereby discuss the case of a child posted for laparoscopic removal of hepatic and renal hydatid cysts, who developed metabolic acidosis with acute renal failure. A 10-year-old child (weight 26 kg) presented with history of pain in epigastrium. Pain was dull, mild to moderate, and there was no radiation. Systemic examination revealed hepatomegaly. Computed tomography scan abdomen revealed well-defined cystic lesion of 12.5 × 8.5 × 11.4 cm in the left lobe of liver extending to lesser sac and perihepatic area along with small cysts in right kidney. Routine blood investigations and liver function tests were normal. Anti-Echinococcus IgG antibody was positive by Enzyme Linked Immunosorbent Assay. Diagnosis of hydatid cyst of liver and kidney was made, and the child was posted for elective laparoscopic removal of hepatic and renal cysts. Baseline haemodynamic parameters were normal for age. Inhalational induction performed with sevoflurane (8%) in oxygen. After administering fentanyl (60 μg) and vecuronium (3 mg), trachea was intubated. A total of 2.5 L of 10% PI (Microwin®10% w/v) was injected into hepatic hydatid cyst. An hour into the procedure, suddenly heart rate increased from 110 to 180/min along with hypercarbia (end-tidal CO255mmHg) and hyperthermia (from 35.1 to 37.4°C). Injection paracetamol (500 mg) and a bolus (0.5 L) of normal saline were infused. An arterial blood gas analysis showed pH 7.14, pCO236.5 mmHg, pO2135 mmHg, SO297.7%, K+7.4 mmol/L, Na+127 mmol/L, Ca+0.81 mmol/L, Cl − 249 mmol/L, lactate 4.3 mmol/L, base deficit - 15 mmol/L, HCO312.7 mmol/L with Hb of 16 gm%. Blood pressure and airway pressures were normal. Urine output decreased and did not improve after first fluid bolus so a further fluid bolus of 0.5 L of balanced salt solution (sterofundin®) and injection frusemide 15 mg intravenous (IV) were administered. Urine output improved and presumptive diagnosis of anaphylaxis due to systemic entry of hydatid cyst fluid was suspected. Injection hydrocortisone and pheniramine maleate were administered. Patient was shifted to intensive care unit (ICU). Investigations revealed haemoglobin 17 g/dL, leukocyte count 49.6 × 103/μL, serum creatinine 0.9 mg/dL, serum albumin 1.9 g/dL, and potassium 5.2 mEq/L in the immediate post-operative period. Liver, renal, and thyroid function tests were in normal range. Severe metabolic acidosis persisted and thus plan for haemodialysis was made. Tachycardia was fluid responsive and Sterofundin®100 ml/h, albumin (20%) 25 ml/h and hydrocortisone 6 mg/h were started. Bedside echocardiography revealed good cardiac contractility, under filled heart chambers and inferior vena cava diameter of 0.4 – 0.8 cm with collapsibility. After 3–4 h of initiation of haemodialysis, acidosis was corrected and heart rate settled. On post-operative day 1, the patient was fully awake and obeying commands. Trachea was extubated after completion of dialysis. Hydrocortisone infusion was tapered and stopped. Patient was kept for another 2 days in ICU for observation before shifting to ward. In its complexed form (i.e. PI), iodine vapour pressure is reduced essentially to zero, and it becomes soluble in water. The available iodine is released at very slow rate from the complex, prolonging germicidal action of free iodine. Povidone-iodine is highly nephrotoxic and due to its renal elimination, iodine intoxication can result in lethal vicious cycle and anuria.[1] Clinically, patients with PI intoxication can present with hypotension, nausea, vomiting, acute renal failure, hypothyroidism, confusion, metabolic acidosis, seizures, blindness, fever, rash, uterine infarction, elevated hepatic enzymes and iodine-induced haemolysis with decreased serum haptoglobin and lactate dehydrogenase levels.[1] Serum iodine levels could not be done as this analysis was not available in our hospital. Labbe et al. reported a case where abnormalities of cardiac conduction, lactic acidosis, acute renal failure, hypocalcaemia and thyroid dysfunction were features of intoxication.[2] In another case report of iodine toxicity in a child with mediastinitis, after median sternotomy, continuous PI irrigation was carried out and the child died due to its toxicity.[3] Iodinated contrast medium (IV) can cause contrast-induced acute kidney injury, but even with non-intravascular use of iodinated compounds, iodine absorption through mucosal, burned skin or interstitial tissues, can cause nephrotoxicity.[4] Early implementation of renal replacement therapy can be lifesaving.

Fundamentos de antisepsia, desinfección y esterilización

This article aims to provide a brief review of the main concepts on which the prevention and control of infection are based. Antisepsis comprises a set of techniques aimed at the total sterilization, or at most, disinfection, removing germs that contaminate an environment. Both procedures must be preceded by an environmental cleanup in the location in which they intend to be applied.The disinfection is carried out using biocides or germicides. Antimicrobial chemicals, that have mechanisms of action and resistances very similar to antibiotics, are generating concern due to the possibility of crossing genetic information that aggravates the problem of bacterial resistance. Most biocides can act as antiseptics, and applied to skin tissue, or disinfectants on inanimate materials. The spectrum of action of germicides depends on the product itself and external controllable factors: temperature, concentration, exposure time, etc.Sterilization techniques are primarily physical, by exposing the material to steam, or sterilizing gas, using autoclaves. Major advances are the use of low temperatures with shorter exposure times, in parallel with technological advances in instrumentation in order to avoid high temperatures and high use rotations due to workload.

Biofilm-forming skin microflora bacteria are resistant to the bactericidal action of disinfectants used during blood donation.

A one-step skin disinfection method containing 2% chlorhexidine-gluconate (CHG) and 70% isopropyl alcohol (IPA) is currently used by blood suppliers worldwide. Reports of bacterially contaminated platelet concentrates (PCs) indicate that skin disinfection is not fully effective. Approximately 20% of skin microflora exist as surface-attached aggregates (biofilms), known for displaying increased resistance to disinfectants. This study was aimed at determining whether skin microflora biofilm-positive Staphylococcus epidermidis and Staphylococcus capitis are resistant to CHG and/or IPA. Free-floating cells and mono or dual (1 : 1 ratio) biofilms of S. epidermidis and S. capitis were exposed to CHG, IPA, or CHG/IPA for 30 seconds, simulating skin disinfection practices. Residual viable cells were quantified by colony counting. Morphology of disinfectant-treated S. epidermidis biofilms was examined by scanning electron microscopy. Treated S. epidermidis and S. capitis biofilms were inoculated into PCs and bacterial concentrations were determined on Days 0 and 5 of storage. Treatment of staphylococcal biofilm cells with all disinfectants caused cell damage and significant reduction in viability, with CHG/IPA being the most effective. However, biofilms were significantly more resistant to treatment than free-floating cells. Disinfectant-treated S. epidermidis proliferated better in PCs than S. capitis, especially when grown as monospecies biofilms. Although CHG/IPA is effective in reducing the viability of S. epidermidis and S. capitis biofilms, these organisms are not completely eliminated. Furthermore, disinfectant-treated staphylococcal biofilms multiply well in PCs. These results demonstrate that the biofilm-forming capability of the skin microflora reduces the bactericidal efficiency of blood donor skin disinfectants.

Selection and microbial control of disinfectants and validation of disinfectant microbial efficacy in the pharma & biopharmaceutical industry: a case study

We have evaluated the efficacy of different neutralizing solutions for use in disinfectant efficacy assays. Our approach used for comparisons between the recoveries of low inocula in different treatment populations. The challenge organisms employed were those described by the Bacilloid special for use in determining germicidal, bactericidal, sporicidal, and fungicidal activity of disinfectants. The manufacturing processes are carried out in controlled environment for which we have classified areas. The microbial load in the classified area must be controlled to ensure asepsis. For this classified areas are regularly disinfected to ensure that the microbial loads are kept under control. The disinfectants are used for sanitization of floors, walls, ceilings, surfaces and other articles in the classified areas of laboratories. It is important to check the disinfectant efficacy before it is used in our facility. This is checked by various methods. The disinfectant used at facility across the sits is Bacillocid special 0.5% v/v for routine monitoring and 2.0% v/v for fumigation purpose. The Bacillocid special contains: 1, 6 Dihydroxy, 2-5 Dioxahexane - 11.2g, Glutaraldehyde – 5.0g, Benzalkonium chloride – 5.0g and Alkyl urea derivatives – 3.0g. Bacillocid special is a disinfectant that is specially designed for the disinfection of high risk areas. It has got excellent cleansing properties, a broad spectrum germicidal action with corrosion inhibitors and cleanser hence this is selected for disinfection. The study was conducted at one location of facility, but the environmental isolates of all facilities were used as a challenged organisms hence the study outcome are applicable for facilities.

English

The aim of this paper was to propose a modeling system of water ultraviolet (UV) disinfection. Results reveal that application of the model of Chick-Watson in its original form or modified are not representative of the kinetics of disinfection. For this reason, the application of a new kinetic model of Collins-Selleck in UV inactivation of Pseudomonas aeruginosa in secondary wastewater appeared to be the best applied model. The modeling of the reactivation process at range of 7.5-50°C temperature was shown. First-order saturation does not fit the obtained data in photoreactivation; a modification of the model is proposed coinciding with the classical logistic equation. To better explain the process of inactivation, we have assumed that the action of disinfectant on the survival of lonely microorganisms is faster than its action on suspended solids protected or agglomerated to each other. For this reason, the application of a new kinetic model by introducing a third factor reflecting the influence of suspended solids in water on disinfection kinetics appeared to be determinant for modeling UV inactivation of P. aeruginosa in secondary treated wastewater. Key words: Secondary wastewater, ultraviolet (UV) disinfection, modeling, photoreactivation. Pseudomonas aeruginosa, suspended solids.

Мас-спектрометричні дослідження взаємодії

In this work the integral components of the cytoplasmic membrane, lecithin and cholesterol were used for mass spectrometry analysis carried out on polyhexamethyleneguanidine (PHMG) mixtures with lipids. The study was performed by mass-spectrometry methods of the MALDI-TOF MS. Our results showed that despite the common use of PHGM polymer derivatives as disinfectants the persistent intermolecular complexes of PHMG oligomers with lipids were not formed. The binding of polycation PHMG with the membrane has been explained by the model proposed. According to this model PHGM can adhere to negatively charged plasma membrane of bacterial cell due to electrostatic interaction and the formation of loop-like structures. Similar stereochemistry mechanism makes the adsorption of the investigated polycation to membrane robust. The mechanism described together with additional destructive factors provides a reasonable explanation for the PHMG induced damage of bacterial cell plasma membrane and the biocide action of disinfectants prepared on the basis of the PHMG salts.

Is hepatitis B-virucidal validation of biocides possible with the use of surrogates?

The hepatitis B virus (HBV) is considered to be a major public health problem worldwide, and a significant number of reports on nosocomial outbreaks of HBV infections have been reported. Prevention of indirect HBV transmission by contaminated objects is only possible through the use of infection-control principles, including the use of chemical biocides, which are proven to render the virus non-infectious. The virucidal activity of biocides against HBV cannot be predicted; therefore, validation of the virucidal action of disinfectants against HBV is essential. However, feasible HBV infectivity assays have not yet been established. Thus, surrogate models have been proposed for testing the efficacy of biocides against HBV. Most of these assays do not correlate with HBV infectivity. Currently, the most promising and feasible assay is the use of the taxonomically related duck hepatitis B virus (DHBV), which belongs to the same Hepadnaviridae virus family. This paper reviews the application of DHBV, which can be propagated in vitro in primary duck embryonic hepatocytes, for the testing of biocides and describes why this model can be used as reliable method to evaluate disinfectants for efficacy against HBV. The susceptibility levels of important biocides, which are often used as ingredients for commercially available disinfectants, are also described.