Activity of selected oxidizing microbicides against the spores of Clostridium difficile: Relevance to environmental control

doi:10.1016/j.ajic.2005.04.240

American Journal of Infection Control

Volume 33, Issue 6, August 2005, Pages 320-325

https://doi.org/10.1016/j.ajic.2005.04.240 Get rights and content

Background

Clostridium difficile is an increasingly common nosocomial pathogen, and its spores are resistant to common environmental surface disinfectants. Many high-level disinfectants (eg, aldehydes) are unsuitable for environmental decontamination because they need several hours of contact to be sporicidal. This study tested the potential of selected oxidative microbicides to inactivate C difficile spores on hard surfaces in relatively short contact times at room temperature.

Methods

The spores of a clinical isolate of C difficile were tested using disks (1 cm diameter) of brushed stainless steel in a quantitative carrier test. The spores of C sporogenes and Bacillus subtilis, common surrogates for evaluating sporicides, were included for comparison. The clostridia were grown separately in Columbia broth (CB), and B subtilis was grown in a 1:10 dilution of CB. Each disk received 10 μL test spores with an added soil load, and the inoculum was dried. One disk each was placed in a glass vial and overlaid with 50 μL test formulation; controls received an equivalent volume of normal saline with 0.1% Tween 80. At the end of the contact time the microbicide was neutralized, the inoculum recovered from the disks by vortexing, the eluates were membrane filtered, and the filters placed on plates of recovery medium. The colony-forming units (CFU) on the plates were recorded after 5 days of incubation. The performance criterion was ≥6 log₁₀ (≥99.9999%) reduction in the viability titer of the spores. The microbicides tested were domestic bleach with free-chlorine (FC) levels of 1000, 3000, and 5000 mg/L; an accelerated hydrogen peroxide (AHP)-based product with 70,000 mg/L H₂O₂ (Virox STF); chlorine dioxide (600 mg/L FC); and acidified domestic bleach (5000 mg/L FC).

Results

Acidified bleach and the highest concentration of regular bleach tested could inactivate all the spores in ≤10 minutes; Virox STF could do the same in ≤13 minutes. Regular bleach with 3000 mg/L FC required up to 20 minutes to reduce the viability of the all the spores tested to undetectable levels; chlorine dioxide and the lowest concentration of regular bleach tested needed approximately 30 minutes for the same level of activity.

Conclusions

Acidified bleach, Virox STF, and regular bleach (3000-5000 mg/L FC) could inactivate C difficile spores on hard environmental surfaces in approximately 10 to 15 minutes under ambient conditions. All of these products are strong oxidizers and should be handled with care for protection of staff, but acidified and regular bleach with high levels of FC also release chlorine gas, which can be hazardous if inhaled by staff or patients.

Section snippets

Test organisms

The C difficile tested was a local clinical isolate from a child and was designated as CHEO. Because the spores of Bacillus subtilis (ATCC 19659) and Clostridium sporogenes (ATCC 7955) are widely used in assessing the sporicidal potential of disinfectants,¹⁷ they were included in this investigation to compare their susceptibility to that of the spores of C difficile. The bacteria were stored at −80°C in appropriate media (see below), plus 10% glycerol.

Sporulation media and culture conditions

The spores of C difficile were prepared by

Results

The numbers of viable spores on the control carriers are summarized in Table 1. Although their titers varied by approximately 1 log₁₀ among experiments, the minimum was always >6 log₁₀. Each value shown is the average of at least 2 repetitions. The values for the viable spores recovered from the test carriers in a given experiment were compared with the control values normalized to 100%; data were expressed as percentage reductions.

However, for infection control purposes, it is important to

Discussion

Although the role of environmental surfaces in the transmission of nosocomial infections is not always recognized, it seems to be supported for CDAD spread.5, 13, 14, 15, 20, 21, 22, 23 Nothing has been published regarding the survival of C difficile spores on inert surfaces after treatment with disinfectants; nevertheless, there are anecdotal as well as published reports10, 24, 25, 26 of a decrease in the transmission of CDAD when oxidative disinfectants such as bleach or AHP are used instead

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Highly persistent, drug-resistant and transmissible healthcare pathogens such as Clostridioides difficile (C. difficile) and Candida auris (C. auris) are responsible for causing antibiotic-associated fatal diarrhea and invasive candidiasis, respectively. In this study, we demonstrate that these potentially lethal gastrointestinal microbes can be rapidly inactivated on the solid surface of a self-disinfecting anionic block polymer that inherently generates a water surface layer that is highly acidic (pH < 1) upon hydration. Due to thermodynamic incompatibility between its chemical sequences, the polymer spontaneously self-organizes into a nanostructure that enables proton migration from the interior of a film to the surface via contiguous nanoscale hydrophilic channels, as discerned here by scanning electron and atomic force microscopies, as well as X-ray photoelectron spectroscopy. Here, we report that two strains of C. difficile in the vegetative state and two species of Candida, Candida albicans (C. albicans) and C. auris, are, in most cases, inactivated to the limit of minimum detection. Corresponding electron and optical microscopy images reveal that, upon exposure to the hydrated polymer, the outer microbial membranes display evidence of damage and intracellular material is expelled. Combined with our previous studies of rapid bacterial and viral inactivation, these antimicrobial results are highly encouraging and, if translatable to clinical conditions in the form of self-standing polymer films or coatings, are expected to benefit the welfare of patients in healthcare facilities by continuously preventing the spread of such potentially dangerous microbes.
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  Disinfection is a process that eliminates many or all microbes, but not bacterial spores, from inanimate objects. It is usually accomplished in hospital environments using liquid chemicals such as quaternary ammonium compounds or accelerated hydrogen peroxide. Proper cleaning is an essential step before disinfection to optimize disinfectant activity, and attention to contact time is also critical.
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  Antisepsis reduces the number of microbes from living tissue and skin. Disinfectants are rarely used for skin antisepsis because they can cause injury to tissues and skin. Chlorhexidine is an example of a commonly used antiseptic.
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  Sanitation is the reduction in the number of microorganisms on a surface to a safe level.
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  Sterilization is the complete elimination of all microbes and can be accomplished in the hospital using techniques such as autoclaving.
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  Germicides are agents that inactivate microorganisms, and include disinfectants, antiseptics, and sanitizers.
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  Veterinarians must be aware of the advantages and disadvantages of different disinfectants, antiseptics, and sterilization processes in order to design and implement an optimal infection control program.
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  Veterinarians should also be aware of items that represent environmental sources of pathogens and the optimal methods to disinfect those items.
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  For detection of hospital bacterial contamination, routine culturing of the environment is not recommended. Fluorescent tagging methods may be useful for demonstration of efficacy of cleaning. In addition, direct observation may also be helpful to identify gaps in protocols and practices. ATP bioluminescence, which detects adenosine 5′-triphosphate (ATP) production by viable microbes in the environment, is a promising tracer to measure hospital contamination with bacteria.
Interlaboratory reproducibility of a test method following 4-field test methodology to evaluate the susceptibility of Clostridium difficile spores
2019, Journal of Hospital Infection
Citation Excerpt :
In 2015, Fraise et al. proposed a reduction requirement of ≥5 log10 reduction in a suspension test [17]. Perez et al. even used a 6 log10 reduction in their study [27]. It is known that approximately one-third of the inanimate surfaces around a patient with CDI are contaminated with C. difficile although higher rates of up to 90% have been reported [5,6,28,29].
Sporicidal surface disinfection is recommended to control transmission of Clostridium difficile in healthcare facilities. EN 17126 provides a method to determine the sporicidal activity in suspension and has been approved as a European standard. In addition, a sporicidal surface test has been proposed.
To determine the interlaboratory reproducibility of a test method for evaluating the susceptibility of a C. difficile spore preparation to a biocidal formulation following the 4-field test (EN 16615 methodology).
Nine laboratories participated. C. difficile NCTC 13366 spores were used. Glutaraldehyde (1% and 6%; 15 min) and peracetic acid (PAA; 0.01% and 0.04%; 15 min) were used to determine the spores' susceptibility in suspension in triplicate.
One-percent glutaraldehyde revealed a mean decimal log₁₀ reduction of 1.03 with variable results in the nine laboratories (0.37–1.49) and a reproducibility of 0.38. The effect of 6% glutaraldehyde was stronger (mean: 2.05; range: 0.96–4.29; reproducibility: 0.86). PAA revealed similar results. An exemplary biocidal formulation based on 5% PAA was used at 0.5% (non-effective concentration) and 4% (effective concentration) to determine the sporicidal efficacy (4-field test) under clean conditions in triplicate with a contact time of 15 min. When used at 0.5% it demonstrated an overall log₁₀ reduction of 2.68 (range: 2.35–3.57) and at 4% of 4.61 (range: 3.82–5.71). The residual contamination on the three primarily uncontaminated test fields was <50 cfu/25 cm² in one out of nine laboratories (0.5%) and in seven out of nine laboratories (4%).
The interlaboratory reproducibility seems to be robust.
ASID/ACIPC position statement – Infection control for patients with Clostridium difficile infection in healthcare facilities
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Many authorities recommend using a cleaning agent that contains chlorine, however, in recent years, new products with sporicidal activity have become available. These include peracetic acid and accelerated hydrogen peroxide containing agents [101,102]. When selecting new agents the user should be familiar with the Therapeutic Goods Administration (TGA) summary of disinfectant regulations in Australia (http://www.tga.gov.au/summary-disinfectant-regulation) and follow the manufacturer's instructions for use.
In 2011, the Australasian Society for Infectious Diseases (ASID) and the Australian Infection Control Association (AICA), now known as the Australasian College of Infection Prevention and Control (ACIPC), produced a position statement on infection control requirements for preventing and controlling Clostridium difficile infection (CDI) in healthcare settings.
The statement updated in 2017 to reflect new literature available .The authors reviewed the 2011 position statement and critically appraised new literature published between 2011 and 2017 and relevant current infection control guidelines to identify where new evidence had become available or best practice had changed.
The position statement was updated incorporating the new findings. A draft version of the updated position statement was circulated for consultation to members of ASID and ACIPC. The authors responded to all comments received and updated the position statement.
This updated position statement emphasizes the importance of health service organizations having evidence-based infection prevention and control programs and comprehensive antimicrobial stewardship programs, to ensure the risk of C. difficile acquisition, transmission and infection is minimised.
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Major ArticleActivity of selected oxidizing microbicides against the spores of Clostridium difficile: Relevance to environmental control

Background

Methods

Results

Conclusions

Section snippets

Test organisms

Sporulation media and culture conditions

Results

Discussion

J Hosp Infect

J Hosp Infect

Am J Med

J Hosp Infect

Am J Med

J Hosp Infect

J Hosp Infect

Am J Infect Control

Clostridium difficile-associated diarrhea and colitis

Infect Control Hosp Epidemiol

Clostridium difficile: a pathogen of the nineties

Eur J Clin Microbiol Infect Dis

Clinical impact and associated costs of Clostridium difficile-associated disease

J Antimicrob Chemother

Antibiotics and hospital-acquired Clostridium difficile-associated diarrhoea: a systematic review

J Antimicrob Chemother

Clostridium difficile-associated diarrhea in adults

Can Med Assoc J

Epidemiology of community-acquired Clostridium difficile-associated diarrhea

J Infect Dis

Recurrent Clostridium difficile colitis: tackling a tenacious nosocomial infection

Postgrad Med

Acquisition of Clostridium difficile from the hospital environment

Am J Epidemiol

Major Article
Activity of selected oxidizing microbicides against the spores of Clostridium difficile: Relevance to environmental control