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.

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

INTRODUCTION

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.

AIM OF THE STUDY

Determination of the minimal sporicidal parameters of a disinfectant containing peracetic acid.

MATERIAL AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Evaluation of the Bactericidal Activity of Didecyl Dimethyl Ammonium Chloride in 2-Propanol against Pseudomonas aeruginosa Strains with Adaptive Resistance to this Active Substance According to European Standards

This study evaluated the bactericidal activity of the cationic surface active compound didecyldimethylammonium chloride in 2-propanol against the two reference strains Pseudomonas aeruginosa and Pseudomonas aeruginosa (tetracycline-resistant) as well as their isolates adapted to this active substance. Individual phases and stages of European Standards which are intended to determine the bactericidal activity of disinfectants in medical areas were used. Disinfection parameters of the tested substance as determined by suspension methods were not sufficient to achieve the required bactericidal reduction in the carrier method for Pseudomonas aeruginosa and all its adapted isolates. Pseudomonas aeruginosa (tetracycline-resistant) and its adapted isolates were more sensitive to the tested active substance when the contact time was extended from 5 to 10/15 min. Adaptive resistance of Pseudomonas aeruginosa strains can be abolished by using increased concentrations of the tested substance and/or extended contact time.

Neutralization efficiency of alcohol based products used for rapid hand disinfection

BACKGROUND

Alcohols are the most commonly used active substances in preparations for quick hand disinfection. They should be bactericidal in very short contact time. PN-EN 13727 + A2: 2015-12 standard, for testing hygienic and surgical handrub disinfection preparations, provides mandatory test conditions of disinfectants in contact times with the range of 30 s to 60 s (hygienic handrub disinfection) and 60 s to 5 min (surgical handrub disinfection). A short contact times for hand hygiene products require a short time of neutralization process. For contact times less than or equal to 10 minutes, the estimated neutralization time is 10 s ± 1 s. Neutralization is a process that abolishes the action of disinfectants. Correct application of this process allows for proper use of disinfectants in practice and its biocidal effect. Objectives. Verification of the effectiveness of 10-second neutralization time of alcohol based preparations for hygienic handrub disinfection

MATERIALS AND METHOD

Neutralization of two products with different ethanol content (89% and 70%) for hygienic handrub disinfection according to PN-EN 13727 + A2: 2015-12 was investigated. The effectiveness of the neutralizer was assessed by determining toxicity of neutralizer, activity of residual effects of the tested products and their derivatives produced during neutralization (10 s) for test organisms (Staphylococcus aureus ATCC 6538; Pseudomonas aeruginosa ATCC 15442; Enterococcus hirae ATCC 10541; Escherichia coli K12 NCTC 10538)

RESULTS

The 10-second neutralization time was sufficient to eliminate the residual activity of products for hygienic handrub disinfection with differentiated ethanol concentration. The neutralizer used did not show toxicity to bacteria and did not produce toxic products with tested preparations after neutralization

CONCLUSIONS

Conclusions. The use of 10-second neutralization time allows in a precise way designate the contact times for hygienic handrub disinfection products

[Significance of efflux pumps in multidrug resistance of Gram-negative bacteria]

The phenomenon of multidrug. resistance of bacteria is a serious problem of modern medicine. This resistance largely is a consequence of abuse and improper use of antibacterial substances, especially antibiotics and chemotherapeutics in hospital settings. Multidrug resistance is caused by a number of interacting mechanisms of resistance. Recent studies have indicated that efflux pumps and systems of efflux pumps are an important determinant of this phenomenon. Contribute to this particular RND efflux systems of Gram-negative bacteria, which possess a wide range of substrates such as antibiotics, dyes, detergents, toxins and active substances of disinfectants and antiseptics. These transporters are usually encoded on bacterial chromosomes. Genes encoding efflux pumps' proteins may also be carried on plasmids and other mobile genetic elements. Such pumps are usually specific to a small group of substrates, but as an additional mechanism of resistance may contribute to the multidrug resistance.

Glucoprotamin antimicrobial activity against selected standard antibiotic-resistant bacteria and reference strains used in the assessment of disinfection efficacy

BACKGROUND

The ability of bacteria to develop common mechanisms of resistance to antibiotics and disinfectants raises doubts about the effectiveness of disinfection processes. Glucoprotamin (GP) is an antimicrobial active substance which is widely used to the disinfection in medical area.

OBJECTIVE

The aim of study was to compare GP's effectiveness with susceptibility of reference strains used for the evaluation of bactericidal efficacy of disinfectants Staphylococcus aureus (S. aureus); Pseudomonas aeruginosa (P. aeruginosa) and standard antibiotic-resistant strains: meticillin-resistant S. aureus (MRSA) and tetracycline-resistant P. aeruginosa (PAO-LAC).

MATERIAL AND METHODS

Minimum inhibitory concentrations (MICs) of GP and minimum bactericidal concentrations (MBCs) against tested strains were evaluated by serial broth dilution technique. GP's efficiency was examined according to qualitative (phenol coefficient GP-PC) and quantitative (EN 1040: 2006) test methods.

RESULTS

Gram-negative strains were more tolerant to GP than Gram-positive strains among tested strains. MRSA and S. aureus exhibited similar susceptibility to GP. PAO-LAC had significantly lower susceptibility to GP than P. aeruginosa (P≤0,05). There were no differences in GP efficiency against these strains based on GP-PC. According to PN-EN 1040: 2006 standard average obligatory reduction≥5 log10 was demonstrated in the active concentration of GP (84 mg/l) at obligatory 5 min contact time for PAO-LAC and P. aeruginosa. The differences in basis bactericidal activity between PAO-LAC and P. aeruginosa were obtained in the active concentration at 10 and 15 min contact time (P≤0,05).

CONCLUSIONS

Variation in a susceptibility of reference strains and antibiotic-resistant standard strains has no meaning at used clinically GP concentrations, which are higher than concentration causing basis bactericidal activity of GP.

Susceptibility of selected strains used for evaluation of biocidal efficiency of disinfectants and antibiotic-resistant strains to didecyldimethylammonium chloride in 2-propanol

INTRODUCTION

Didecyldimethylammonium chloride is an active substance which is part of variety of formulations used for the disinfection and antisepsis, both in the medical area as well as in the food, industrial and institutional area. Because of the widespread use of this substance and the development of bacterial resistance to quaternary ammonium compounds (QACs), the aim of this study was determination of the susceptibility of the standard strains used for the evaluation of the effectiveness of disinfectants and standard antibiotic-resistant strains to didecyldimethylammonium chloride in 2-propanol and its bactericidal activity.

METHODS

Susceptibility of standard strains used for the evaluation of the effectiveness of disinfectants (Staphylococcus aureus ATCC 6538-SA; Pseudomonas aeruginosa ATCC 15442-PA) and standard antibiotic-resistant strains (Staphylococcus aureus ATCC 43300-MRSA; Pseudomonas aeruginosa ATCC 47085-PAO-LAC) to CMAP was determined by minimum inhibitory concentrations (MICs) and minimum bactericidal concentration (MBCs). The bactericidal efficiency of CMAP against these strains was evaluated by using phenol coefficient (PC).

RESULTS

Susceptibility of Gram-positive tested strains SA and MRSA to CMAP was similar (P>0,05). Significant difference in susceptibility of tested Gram-negative strains to CMAP was evaluated between PA and PAO-LAC strains (P<0,05). However,.higher resistance of PAO-LAC to CMAP was not significant when parameters such as concentration and contact time were applied in PC method.

CONCLUSIONS

The correct determination and application of "in use" parameters (i.e. concentration, contact time, temperature and interfering substances) in disinfection process prevents the spread of resistant strains in.the environment.

Effect of different drying conditions for the viability of Candida albicans present on carriers

BACKGROUND

Problems in substantial under recovery of Pseudomonas aeruginosa and Candida albicans from carriers have been demonstrated for laboratories performing phase 2, step 2 efficacy tests on disinfectants relative to levels required by the EN 13697 standard. It was thus necessary to determine recoveries of these microorganisms following procedural losses incurred during drying and to optimise drying conditions such that recoveries then complied with the standard.

OBJECTIVES

The aim of the study was to establish optimal drying conditions for the recovery of Candida albicans ATCC 10231 from carriers.

MATERIALS AND METHODS

The evaluation was performed according to the EN 13697:2001 standard procedure. A test suspension of Candida albicans and interfering substance were inoculated onto the surface of carriers (2 cm diameter stainless steel discs) and then dried under different conditions consisting of: a 37 degrees C incubation with and without an incubator fan as well as at 23 degrees C (room temperature) in a laminar air flow cabinet. Carriers were dried until the surfaces appeared visibly dry and the number of surviving organisms then recovered from the surface were quantified. The following were calculated for colony forming units (cfu); N (log10 cfu in a 0.05 ml test suspension), NC (the control log10 cfu in neutralizing medium), Nts (cfu numbers remaining on the surface) and the N-NC difference which should not exceed 2 log10 when microorganism recoveries are adequate and without any toxicity effects of the neutralising medium. Experiments was conducted using validating procedure (NC) which is performed with distilled water.

RESULTS

Drying at 37 degrees C adversely affected the survival of Candida albicans and prevented the levels of microbial recovery from carriers to reach those specified by the EN 13697 standard. However, drying at around room temperatures of 23 degrees C reduced Candida albicans mortality and increased recoveries from the carrier to levels compliant with the standard, where the N-NC differences were not greater than 2 log10.

CONCLUSIONS

The viability of Candida albicans ATCC 10231 is sufficiently improved when carriers are dried at 23 degrees C, even if the drying time exceeds 60 minutes. The density of the initial test suspension (N) should also be increased.

Effect of adaptation process of Pseudomonas aeruginosa to didecyldimethylammonium chloride in 2-propanol on bactericidal efficiency of this active substance

BACKGROUND

Microorganisms are characterized by two types of resistance innate and acquired. Innate resistance is associated with the construction of the surface structures. Wide use of active substances as antimicrobial compounds, especially in inhibitory concentrations, may promote the acquisition of bacterial resistance to these substances in the process of adaptation.

OBJECTIVE

The aim of the study was to determine changes in efficiency of didecyldimethylammonium chloride in 2-propanol (CMAP) against the Pseudomonas aeruginosa strains, which were adapted to this active substance.

MATERIALS AND METHODS

Adaptation studies were conducted using two strains: P. aeruginosa ATCC 15442 (PA), which is used in estimation of biocide efficiency and tetracycline-resistant P. aeruginosa ATCC 47085 (PAO-LAC) strain. These strains were adapted to the active substance Bardac22: 50% v/v didecyldimethylammonium chloride in 20% v/v 2-propanol (CMAP) according to the National Institute of Hygiene procedure. After adaptation, obtained isolates were classified to three groups and passaged to solid media: A - strains unadapted passaged onto slant medium without active substance, control group; B - strains with adaptive resistance passaged onto slant medium with 375 mg/l CMAP; C - strains with adaptive resistance passaged onto slant medium without CMAP. Changes in susceptibility of examined strains were determined on the basis of minimum inhibitory concentrations (MICs) by broth dilution method. The minimum bactericidal concentrations (MBCs) were determined by subculture P. aeruginosa strains on solid media without CMAP. The efficiency of CMAP against isolates obtained after adaptation processes was evaluated by using phenol coefficient (PC).

RESULTS

There were no differences in the adaptation process between two strains of P. aeruginosa: PA and PAO-LAC. Both isolates obtained after the adaptation process was characterized by approximately 6-8 fold higher MICs compared to the MICs of these strains before the adaptation. Strains passaged to a solid media characterized a variable sensitivity to CMAP. As compared to a control group A, the isolates of PA and PAO-LAC from group B and isolate PA from group C exhibited the highest and stable insensitivity (MIC from > 700 to >1000 mg/l) to 48-49 passages. Isolates from group C of PAO-LAC maintained insusceptibility up to 20th passage (MIC >375 mg/l). There were no statistically significant changes in the CMAP bactericidal efficacy against isolates of reduced sensitivity.

CONCLUSIONS

Adaptation of P. aeruginosa strains to didecyldimethylammonium chloride in 2-propanol does not significantly change bactericidal efficacy of this active substance against isolates with reduced sensitivity. Antibiotic-resistant strain PAO-LAC showed a similar adaptability and a similar sensitivity to the CMAP as a strain PA used to assess the effectiveness of disinfectants.

KEY WORDS

adaptation process, Pseudomonas aeruginosa, quaternary ammonium compounds, bactericidal efficiency.

Recommendations for thermal disinfection based on the A0 concept according to EN ISO 15883

The use of aseptic instruments for the care of patients is an essential element in the prevention of nosocomial infections. Significant risks have been associated with inadequate or improper cleaning and disinfection of reusable medical devices. Thermal disinfection with moist heat, based on the A0 concept (EN ISO 15883-1), is the most common method for disinfection of medical devices in the hospital setting. A0 is a physical parameter denoting the inactivation of microorganisms. The concept of A0 is intended to allow equivalent disinfection efficiencies to a reference time/temperature to occur at other disinfection temperatures. This paper focuses on parametric control of thermal disinfection--A0 values as recommended in the standard and their interpretation. The experimental fundamentals regarding of an A0 concept are rare. Data on thermal disinfection are partly contradictory. The washer disinfectors use thermal disinfection programs set in accordance with the parameters: time and temperature, which is proven suitable biocidal activity, not based on the A0 value. Many authorities in the field of disinfection recommends to use higher values of A0 than those specified in the standard EN ISO 15883.

[Significance of the efflux phenomenon as a mechanism of bacterial resistance on active substances of biocide]

Efflux phenomenon induced by the presence of efflux pumps is one of the bacterial resistance mechanisms against active substances ofbiocides. Proteins and protein systems create efflux pumps, which are connected with the cell envelope structure ofbacteria. The efflux pump's function is transportation of active substances of disinfectants outside the bacterial cell. The biocides active substances rinsed out of bacterial cell by efflux were described for quaternary ammonium compounds, biguanides, phenols and diamidine. Bacterial resistance induced by efflux was not confirmed in the presence of such active substances like: alcohols, aldehydes, peroxides and chlorine compounds and their derivates. Bacterial resistance to active substance ofbiocides can be caused by two or more resistance mechanisms i.e. efflux mechanisms and reduce diffusion. The cooperation of resistance mechanisms to biocides can result difficulties in pathogenic bacteria eradication. The spread of these bacteria can be an epidemic threat.

[Assessment of decontamination processes: cleaning, disinfection and sterilization in dental practice in Poland in the years 2011-2012]

OBJECTIVE

Effective decontamination of instruments is a key element of infection control and the provision of high quality in dental care. The aim of the study was to evaluate the efficiency of decontamination procedures including cleaning, disinfection and sterilization of re-usable instruments in dental practices in Poland.

MATERIAL AND METHODS

The efficiency of disinfection and sterilization processes have been evaluated on the results of the questionnaires. The following information were taken into account: setting where disinfection and sterilization had been performed, preparation of dental equipment for sterilization (disinfection, washing and cleaning, packaging), the types of autoclaves and used types of sterilization cycles, routine monitoring and documentation of sterilization processes, treatment of handpieces and the frequency of surface decontamination.

RESULTS

Data were collected from 43 dental practices (35 dental offices and 8 clinics). Disinfection and cleaning processes were performed manually in 63% of dental offices and ultrasonic baths were used in 53% of settings. Washer disinfectors were used in 23% of dental practices: in every researched clinic and in a few dental offices. All sterilization processes were performed in steam autoclaves, mainly in small steam sterilizers (81%). Dental handpieces were sterilized in 72% of practices, but only 33% of them performed sterilization in recommended cycle B. Sterilization processes were monitored with chemical indicators in 33% of practices. Biological monitoring of the processes was carried out at different intervals. Incorrect documentation of instruments and surfaces decontamination was recorded in several settings.

CONCLUSIONS

There is still a need for improvement of decontamination processes in dental practice in Poland. Areas for improvement include: replacement of manual cleaning and disinfection processes with automatic processes, sterilization of dental handpieces after each patient, monitoring of a sterilization process with chemical and biological indicators. Reported incorrect procedures in decontamination of medical devices performed by questioned dentists and lack or inadequate response to asked questions indicate the lack of adequate knowledge about decontamination. Personnel who performs decontamination processes should be continuously trained.

[Waste generated in Polish hospitals during the years 2005 - 2009]

The medical institutions generate mainly municipal and medical waste. The medical waste includes infectious waste, dangerous but not infectious waste (toxic) and medical not dangerous waste. They have to be correctly identified, properly sorted and suitably neutralized. Questionnaires investigations were conducted on the basis on the forms worked out at National Institute of Public Health - National Institute of Hygiene. Information from above seven hundred seventy hospitals were collected. Inquiries indicated that during the period of years 2005-2009 over two hundred thousand beds per year were available. The degree of the use run from 52% to 100%, in average 72%. The largest fraction of the waste from all institutions were municipal waste run from 80% to 90%. Dangerous waste in following years were between 9.9% and 18.1%. The great part of dangerous waste were infections waste, which content ranged from 8.7 to 17.1%. Very low quantity of medical not dangerous waste was noted (1-1,7%). The majority of infectious medical waste were neutralized outside hospitals by the companies having suitable permissions. The thermal conversions (burning) was the most often used method.

[Microbiological assesssment of efficiency chemothermal disinfection of blood contaminated hospital textiles]

Thermal disinfection should be applied to laundering procedures of hospital textiles contaminated with blood. Currently, there is an increasing number of hospital textiles composed of cotton-polyester blends that cannot endure high temperatures of thermal disinfection. Besides, decreasing the temperature of chemothermal disinfection enhances the possibility of micro-organisms to survive the laundering procedure. The aim of this study was to prepare a new method for the microbiological evaluation of disinfecting laundering procedures for hospital textiles contaminated with blood. The bactericidal activity of chemical disinfectants for chemothermal disinfection was determined by simulating a laundering procedure for hospital textiles in the laboratory according to procedure of National Institute of Hygiene - DF/05/03. Bioindicators cotton carriers inoculated with Enterococcus faecium were used for determinating the antibacterial effects for hospital textiles contaminated with blood. High concentrations of bovine albumin and/or sheep erythrocytes were used as substrate for simulating human blood. The results showed that the bactericidal activity of chemical disinfectants for chemothermal disinfection hospital textiles in the event of massive organic contamination--heavily soiled with blood, shall be evaluated using carrier test in following conditions: test organism- Enterococcus faecium, interfering substances--6 g/l bovine albumin solution added to preparation.

[The effect of antibacterial substances on spread resistance of bacteria]

The evaluation of influence biocides on phenomenon of spread resistance bacteria is wide discussed particularly in the medical area. Current issue is examinated mechanisms of spread bacterial resistance in the areas using antibiotics and disinfectants and in natural environment. Selection of resistance bacteria is connected with using biocides against the rules in medical care and disinfection. Biocides using in static concentrations do not act as bacteriocidal substances and contribute to survival rate of resistance bacteria. Disinfectants use correctly to the areas and in right using concentrations prevent spread of resistance bacteria.

[Assessment of disinfection and sterilization processes in dental practice as an important factors in prevention of infections]

The dental health-care settings is an environment where disease transmission occurs easily. Prevention of cross infection is therefore a crucial aspect of dental practice and dental clinic stuffmust adopt certain basic routines while practicing. Infections may be transmitted in the dental operatory through direct contact with blood, oral fluids or other secretions; via indirect contact with contaminated instruments, equipment or environmental surfaces; or by contact with airborne contaminants present in either droplet splatter or aerosols of oral and respiratory fluids. Strategies to prevent dental patient infections have focused on disinfection and sterilization. This study evaluates basic routines in prevention of cross-infection in the dentistry. The sample comprised 100 dentists, who completed questionnaires. Based on inquires the conditions for disinfection and sterilization of medical devices were assessed. The following issues were taken into consideration: the way of disinfection and preparation of the disinfectants, the localization of disinfection, preparing to disinfection, washing and packing of dental devices, the frequency of disinfection, methods of sterilization and the monitoring system, type of sterilizers and the available cycles. The dental practices are well equiped to proceed the steam sterilization, but 33% of dentists don't know the available cycles in their autoclaves. Only 35% of them made sterilization process protocols. Very common are three failures of instruments disinfections: multiple use of disinfectant, adding of disinfectant, adding new instruments. There is still need for improvement in disinfection and sterilization in dental practice, especially including: monitoring and documentation of sterilization process, proper use of disinfectants according to manufactures instructions, frequent disinfection of surfaces which contact with patients. Dental stuff should take part in advanced training courses about disinfection and sterilization.

[The wastewater treatment significance in the control sanitarian and epidemiological state of environment]

The municipal wastewater consist of organic, inorganic and biological contaminations. The most of human and animals pathogens are found in municipal wastewater responsible for water-borne and waterwashed diseases. Wastewater biological treatment is effective methods to reduce the transmission route of this pathogens. Different kind of methods (microfiltration/coagulation) and technology (aerobic/anaerobic stabilization) treated municipal wastewater, secondary effluent, primary and excess sludge are used to inactivation viruses, bacteria and protozoan. Chemical disinfection with CaO significantly affects inactivation of helminthes eggs during the hygienization of sludge. However the efficiency of pathogens disinfection particularly depend on contact time and concentration of disinfectants.