Evaluation of Low-Temperature Sterilization using Hydrogen Peroxide Gas Containing Peracetic Acid.

In low-temperature sterilization for the medical field, hydrogen peroxide sterilization is widely used for its safety. However, its low penetrability and residual amount of sterilant are major concerns. Recently, the combination of hydrogen peroxide and peracetic acid has been found to enforce sporicidal effect, with low concentration in hydrogen peroxide. The application of this finding in medical sterilization is still very limited. To elucidate the combination effect, we compare peracetic acid containing hydrogen peroxide gas sterilizer and conventional hydrogen peroxide gas (plasma) sterilizers. The sterilant penetrability was examined in hollow load process challenge devices with inner diameters of 1 and 2 mm and lengths of 1, 2, and 3 m. As a result, peracetic acid containing hydrogen peroxide gas sterilizer demonstrated total inactivation with all diameters and lengths and achieved the highest sterilant penetrability in this study. The amount of residual sterilant on the surface of the sterilized object was 4.2 µg/cm2, which corresponds to half amount of those of conventional hydrogen peroxide gas sterilizers. These results suggest that the addition of peracetic acid to hydrogen peroxide gas sterilizer can enhance sterilization efficiency and safety.

Ação de diferentes sanitizantes em biofilmes de Salmonella Minnesota / Action of different sanitizers in biofilmes of Salmonella Minnesota

Objetivou-se avaliar a eficiência do contato por 15 minutos do hipoclorito de sódio 1%, e ácido peracético 0,8% na inibição de biofilmes formad os por três cepas distintas de Salmonella Minnesota em aço, poliuretano e polipropileno e determinar a recuperação das células remanescentes. Qualitativamente houve influência na classificação dos biofilmes de acordo com a superfície, que foram diferentes dependendo do tipo de cepa e de material, porém a quantidade de células sésseis permanece constante, pois independente da cepa e da superfície, os biofilmes mantiveram uma contagem de 5,18 Log UFC, indicando que as diferenças referem-se à matriz polimérica. O uso do hipoclorito foi capaz de destruir as células, que não foram recuperadas após reincubação. Já o ácido peracético não promoveu redução significativa. O uso do hipoclorito de sódio 1% é eficiente na sua remoção.

Microbiological surveillance of flexible bronchoscopes after a high-level disinfection with peracetic acid: preliminary results from an Italian teaching hospital.

BACKGROUND: Flexible bronchoscopes are heat labile, complex and difficult to clean, and some nosocomial outbreaks related to bronchoscopy have been reported in literature. The aim of our study was to determine, through a systematic monitoring, whether bronchoscopes' cleaning and disinfection procedures have been correctly adopted by health operators. METHODS: We conducted a 19 months-long prospective study in the Unit of Pulmonology at Careggi Teaching Hospital (Florence, Italy), analyzing endoscopes that were reprocessed through a high-level disinfection procedure. Samples collection was performed weekly by two trained operators. Results were organized in a database and then exported for descriptive and inferential statistical analysis. RESULTS: From February 2016 to September 2017 we collected 218 samples from bronchoscopes' valves (N=109) and from their inner channels (N=109). Staphylococci were found in 34 samples (15.69% of all samples). Pseudomonas was found in 11 samples (5.04% of all samples). Pseudomonas aeruginosa wasn't found in any sample. CONCLUSIONS: Our results came out to be better than similar studies in literature and demonstrated that a correct endoscopes' hygiene should be part of a more complex strategy of surveillance and control of healthcare-associated infections. However, a continuous monitoring of endoscopes could provide a wider view about this problem, and more reliable results.

Estabilidade do ácido peracético no processo de desinfecção prévia à lavagem / Peracetic acid stability in disinfection process prior to wash

Objetivo: Avaliar a efetividade antimicrobiana e a estabilidade de formulações de ácido peracético com (Apc) e sem inibidor (Aps) de corrosão. Materiais e Métodos: Corpos de prova em aço inoxidável foram contaminados com Staphylococcus aureus, Escherichia coli, Candida albicans, sangue e saliva e imersos em ácido peracético (Aps e Apc) por dez, quinze e trinta minutos. Após estes períodos, Apc e Aps foram neutralizados, agitados durante um minuto e a suspenção obtida foi semeada (ágar sangue), incubada (24h/37 °C) e as unidades formadoras de colônia (UFC) contadas. Este procedimento foi realizado seis vezes ao dia por 18 dias não consecutivos por um período de trinta dias. Corpos de prova contaminados e não submetidos à desinfecção foram utilizados como grupo controle. Resultados: Houve redução significativa das médias diárias de crescimento dos microrganismos para os dois grupos teste (Aps e Apc) quando comparados ao grupo controle (p= 0,0000) sem diferença estatística significativa entre eles (p= 0,7517). Conclusão: As duas soluções de ácido peracético mostraram-se eficientes no processo de desinfecção, sendo a solução sem inibidor de corrosão estável por um período maior...

Objective: To evaluate the stability of formulations of peracetic acid with (Apc) and without inhibitor (Aps) of corrosion in the disinfection process prior to washing. Materials and Methods: Specimens of stainless steel were contaminated with Staphylococcus aureus, Escherichia coli, Candida albicans, blood and saliva and immersed in peracetic acid (Aps and Apc) for ten, fifteen and thirty minutes. After these periods, Aps and Apc were neutralized, stirred and the suspension obtained was seeded (blood agar) incubated (24h/37°C) and colony forming units counted. This procedure was carried out six times a day for 18 consecutive days for a period of thirty days. Contaminated specimens and not disinfected were used as control group. Results: There was significant reduction in the daily growth average of microorganisms for the two test groups (Aps and Apc) when compared to control group (p = 0.0000) with no significant statistical difference between them (p = 0.7517). Conclusion: The two solutions of peracetic acid were effective in the disinfection process, with the solution without corrosion inhibitor stable for a longer period...

Uso de ácido peracético e dióxido de cloro como agentes antimicrobianos em carne de frango / Use of peracetic acid and chlorine dioxide as antimicrobials in chicken

A qualidade microbiológica e a segurança alimentar são assuntos que têm ganhado cada vez mais importância na área de alimentos. Várias tecnologias para a descontaminação de micro-organismos em produtos cárneos têm sido investigadas. A adição de interventores químicos, como dióxido de cloro e ácido peracético também tem sido fonte para a realização de diversos estudos. Este trabalho objetivou determinar a eficiência do ácido peracético e dióxido de cloro no tratamento para a conservação de sobrecoxas de frango.

[Study on cytotoxicity of microdoses peracetic acid in vitro].

OBJECTIVE: To evaluate the cytotoxicity of microdoses peracetic acid (PAA) so as to provide the evidence for making residual limit of PAA sterilization. METHODS: Mouse fibroblasts (L929 cell line) cultured in vitro were observed to evaluate the influence of microdoses PAA including 1 x 10(-6), 2 x 10(-6), 3 x 10(-6), 4 x 10(-6), 5 x 10(-6), and 10 x 10(-6) (V/V). The proliferation of cells was determined by MTT assay at 2, 4, and 7 days of culture. The growth curve and the relative growth rate (RGR) were obtained. The cytotoxicity of PAA at different concentrations was evaluated according to RGR. RESULTS: At 2, 4, and 7 days after culture, fibroblasts of 1 x 10(-6) group grew with normal morphology analogous to control group, while the cell growth of other groups were poor. With the increase of PAA concentration, the absorbance (A) values decreased, which suggested that there was a significant negative correlation between cell proliferation and PAA concentration. And the correlation coefficient was -1.000 at 2 and 4 days, - 0.964 at 7 days. There was no significant difference in A value between 1 x 10(-6) group and the control group (P > 0.05), while there were significant differences in A value between the control group and other concentration groups (P < 0.05). The growth curve of 1 x 10(-6) group was similar to that of the control group, both had obvious phase of exponential growth. The growth curves of other groups had no obvious phase of exponential growth. The cytotoxicity of 1 x 10(-6) group was classified as level 1, 2 x 10(-6) group as level 2, 3 x 10(-6) group as level 3, 4 x 10(-6) group as level 3-4, 5 x 10(-6) group and 10 x 10(-6) group as level 4. CONCLUSION: PAA of 1 x 10(-6) had no obvious cytotoxicity. The residual limit of PAA less than 1 x 10(-6) was recommended.

A influência da imersão em ácido peracético sobre a reprodução de detalhes e compatibilidade dos elastômeros com gesso / The influence of peracetic acid immersion on detail reproduction and compatibility of elastomers with gypsum

O objetivo deste trabalho foi verificar a influência da imersão no desinfetante à base de ácido peracético 0,2% sobre a reprodução de detalhes e compatibilidade com gesso dos elastômeros: Silicona de Adição, Silicona de Condensação e Poliéter. Para a reprodução de detalhes foram confeccionados 10 corpos de prova de cada material utilizando-se a matriz determinada pela especificação n. 19 para Materiais de Impressão Elastoméricos Não-Aquosos da A.D.A., sendo que 5 corpos de prova foram imersos no desinfetante por 10 minutos e os outros 5, utilizados como controle. A reprodução de detalhes foi analisada pela visualização de uma linha de 30 mm de comprimento e 20 μm de espessura de forma completa e contínua em pelo menos duas de três impressões, segundo a especificação. Para compatibilidade com gesso avaliou-se a reprodução dos mesmos detalhes nos modelos vazados com gesso tipo IV sobre as referidas impressões. Todos os materiais utilizados apresentaram reprodução de detalhes e compatibilidade com gesso em 100% dos corpos de prova. Concluiu-se que a imersão no desinfetante à base de ácido peracético não alterou as propriedades avaliadas destes materiais.

Mutagenicity in lung of big Blue((R)) mice and induction of tandem-base substitutions in Salmonella by the air pollutant peroxyacetyl nitrate (PAN): predicted formation of intrastrand cross-links.

Peroxyacetyl nitrate (PAN) is a ubiquitous air pollutant formed from NO(2) reacting with acetoxy radicals generated from ambient aldehydes in the presence of sunlight and ozone. It contributes to eye irritation associated with photochemical smog and is present in most urban air. PAN was generated in a chamber containing open petri dishes of Salmonella TA100 (gas-phase exposure). After subtraction of the background mutation spectrum, the spectrum of PAN-induced mutants selected at 3.1-fold above the background mutant yield was 59% GC-->TA, 29% GC-->AT, 2% GC-->CG, and 10% multiple mutations - primarily GG-->TT tandem-base substitutions. Using computational molecular modeling methods, a mechanism was developed for producing this unusual tandem-base substitution. The mechanism depends on the protonation of PAN near the polyanionic DNA to release NO(2)(+) resulting in intrastrand dimer formation. Insertion of AA opposite the dimerized GG would account for the tandem GG-->TT transversions. Nose-only exposure of Big Blue((R)) mice to PAN at 78ppm (near the MTD) was mutagenic at the lacI gene in the lung (mutant frequency +/-S.E. of 6.16+/-0.58/10(5) for controls versus 8.24+/-0.30/10(5) for PAN, P=0.016). No tandem-base mutations were detected among the 40 lacI mutants sequenced. Dosimetry with 3H-PAN showed that 24h after exposure, 3.9% of the radiolabel was in the nasal tissue, and only 0.3% was in the lung. However, based on the molecular modeling considerations, the labeled portion of the molecule would not have been expected to have been bound covalently to DNA. Our results indicate that PAN is weakly mutagenic in the lungs of mice and in Salmonella and that PAN produces a unique signature mutation (a tandem GG-->TT transversion) in Salmonella that is likely due to a GG intrastrand cross-link. Thus, PAN may pose a mutagenic and possible carcinogenic risk to humans, especially at the high concentrations at which it is present in some urban environments.

Peroxyacetyl nitrate: review of toxicity.

PAN is one of a class of common air pollutants formed by the action of sunlight on volatile organic compounds and nitrogen oxides. No toxicokinetic studies have been found in the available literature. The acute toxicity of PAN is less than that of ozone, similar to NO2 and higher than SO2. The LC30, in mice and rats were 718-743 mg/m3 (for 2 h) and 470 mg/m3 (for 4 h), respectively. Following acute exposure, severe lung lesions and, at the higher levels, damage to the epithelium of upper parts of the respiratory tract were found in animals. It seems that concentrations of 1.19-1.49 mg/m3 lie not far from the threshold required for pulmonary function effects in sensitive individuals. However, these PAN concentrations are well above the maximum ambient concentrations usually experienced within the USA and Canada (0.003-0.078 mg/m3). It appears unlikely that present ambient PAN concentrations would affect pulmonary functions responses to ambient ozone. In human, the lowest level causing eye irritations was 0.64 mg/m3 for 2 h. Concentrations of 0.99 and 4.95 mg/m3 were identified as no-observed-effect level (NOEL) and no-observed-adverse-effect level (NOAEL) for pathological and histological changes in the respiratory system (nasal passages) of rats during subchronic exposures to PAN, but were not considered to be relevant to derivation of a RfC for chronic inhalation exposure. PAN is a weak point mutagen or clastogen. The data are not sufficient to evaluate its carcinogenicity. No study was found which could be used for the derivation of a RfC for acute or chronic inhalation exposure to PAN.

[Subacute and subchronic percutaneous tolerance testing (28-day and 90-day test) of epicutaneously applied dis-infectants as demonstrated by the example of peroxyethanoic acid (author's transl)]. / Subakute und subchronische percutane Verträglichkeitsprüfung im 28-und 90-Tag-Test von Desinfektionsmitteln bei epicutaner Applikation, dargestellt am Beispiel von Peroxyethansäure.

As compared to control animals, guinea-pigs to the shaved backs of which a dose of 0.16 ml of a 0.12% solution of PES/100g. of body mass had been applied twice daily for periods of 28 and 90 d, respectively (5 d of application being followed by 2 d without treatment), showed erythema, loss of hair, slower increase in mass, increased heart rate, smaller body mass/kidney mass and body mass/spleen mass ratios, increases in leucocytes, ASAT, ALAT, LDH I and LDH III. In the 28-d test, slight inflammatory symptoms of the liver, kidneys and heart were observed in the experimental animals. These symptoms were more marked in the 90-d test, granulomata in the livers being particularly striking. A pneumonia of moderate to very marked degree is suggestive of the activation of a clinically latent PES infect whereby the inflammatory alterations in the kidneys might be explained by the formation of metastases.

Action of chronic peracetic acid (Wofasteril) administration on the rabbit oral mucosa.

Peracetic acid Wofasteril) is increasingly made use of as a disinfecting fluid. Because of its high effectiveness it has found widespread use in medical practice. The action of Wofasteril on the oral mucosa during long-term action is studied by aid of an "oral tank". After a test period of 11 months peracetic acid only caused a slight ballooning of the superficial layers and enhanced vascularization of the submucous tissue. The results of the experiment suggest the intraoral administration of peracetic acid in oral surgery and stomatology.