Uso de biocidas y mecanismos de respuesta bacteriana / Use of biocides and bacterial response mechanisms

La constante aparición de microorganismos que incrementan su tolerancia a sustancias utilizadas para su control como los biocidas está generando atención en salud pública y debe ser estudiado, teniendo en cuenta los diversos riesgos que se pueden enfrentar principalmente en pacientes con alta susceptibilidad a las infecciones asociadas a la atención en salud, dado que estos biocidas son utilizados cotidianamente lo que ha generado mecanismos bacterianos como lo son la formación de biopelículas y aquellos que incrementan su tolerancia como la generación de bombas de flujo. Esta respuesta bacteriana a la presión de los biocidas se potencia por la aparición de microorganismos resistentes a los antimicrobianos de uso en el tratamiento y control de las infecciones lo que hace difícil el control de estos. Se realizó una revisión de literatura disponible en las bases de datos Proquest, ovid, Science direct, PubMed, donde se encontraron un total de 103 artículos y se seleccionaron 73, de acuerdo con el año de publicación en los idiomas español e inglés, que incluyeron estudios descriptivos y de revisión. El objetivo de este artículo fue realizar una revisión acerca de los principales mecanismos de acción de biocidas y la respuesta de tolerancia que presentan los microorganismos frente a estos; lo que conlleva a la reflexión sobre las implicaciones del uso de estas sustancias sobre la salud humana.

The constant appearance of microorganisms that increase their tolerance to substances used for their control such as biocides is generating attention in public health and should be studied, taking into account the various risks that can be faced mainly in patients with high susceptibility to infections associated with health care, given that these biocides are used on a daily basis, which has generated bacterial mechanisms such as the formation of biofilms and those that increase their tolerance, such as the generation of flow pumps. This bacterial response to the pressure of the biocides is enhanced by the appearance of microorganism's resistant to the antimicrobials used in the treatment and control of infections, which makes their control difficult. A literature review was made available in the databases Proquest, ovid, Science direct, PubMed, where a total of 103 articles were found and 73 were selected, according to the year of publication in the Spanish and English languages, which included Descriptive and review studies. The objective of this article is to carry out a review about the main action mechanisms of biocides and the tolerance response presented by microorganisms against them; which leads to reflection on the implications of the use of these substances on human health.

Biocide tolerance in Salmonella from meats in Southern Spain

Salmonella serovars sampled from meat products in Southern Spain (Andalucía) during the period 2002-2007 were analyzed in this study. The serovars most frequently detected (in order) were Typhimurium, Enteritidis, Derby, Anatum and Rissen. Isolates (n = 43) were tested for sensitivity to biocides, including the quaternary ammonium compounds benzalkonium chloride (BC), cetrimide (CT) and hexadecylpyridinium chloride (HDP), and the bisphenols triclosan (TC) and hexachlorophene (CF). The minimum inhibitory concentration (MIC) for the quaternary ammonium compounds was in the range of 25 to 50 mg/L for most isolates, although a few isolates required much higher concentrations, up to 250 mg/L. Bisphenols showed higher inhibitory activity, with a MIC of 2.5 to 25 mg/L. A few isolates showed a “non-wildtype” MIC for TC of up to 250 mg/L. These results indicate a low incidence of tolerance towards quaternary ammonium compounds and triclosan among Salmonella from meats and meat products.

Impacts of Some Non-oxidizing Biocides on the Functional Group Activities of Some Problem Causing Microorganisms in Oil Production Facilities.

Aim: To determine the impacts of some non-oxidizing biocides such as glutaradehyde, sodium azide, isothiazolone on the functional group activities of some oil field microorganisms Methodology: Samples of non-oxidizing biocides were obtained from Microcheck and the inhibition of some functional group activities in produced and injection water samples were determined using CSB-K medium. Results: Glutaradehyde and sodium azide exhibited relatively high level inhibition while isothiazolones exhibited low level inhibition. Glutaradehyde further demonstrated a positive selective inhibitory activity. While SRB activities were inhibited by over 78%, that of hNRB and so-NRB were affected by less than 38%. Conclusion: Glutaradehyde can be developed to an efficient biocide with a positive selective action and can work in synergy with beneficial microbes to eliminate the problem causing ones.

The level of Inhibition of Microbial Functional Group Activities by Some Oxidizing Agents Commonly used as Biocides in Oil field Operations.

Aim: To determine the level of inhibition of microbial functional group activities such as the ability to reduce sulfate to sulfide by sulfate reducing bacteria (SRB), reduce nitrate to nitrite by the heterotrophic nitrate reducing bacteria (hNRB), and oxidize sulfide and reduce nitrate by sulfide oxidizing, nitrate reducing bacteria (so-NRB) by some oxidizing biocides like chlorine, bromine and ozone. Methodology: Samples of the oxidizing biocides were obtained from Microcheck and the inhibition of some functional group activities in produced and injection water samples were determined using CSB-K medium. Results: Ozone was found to be more effective than chlorine and bromine in the inhibition of functional group activities at lower concentrations. Conclusion: More research effort is required to see if ozone can work in synergy with other biocides to improve on its efficiency.

DesinFix TM 135 in fermentation process for bioethanol production

Brazil has the world's largest ethanol production from sugarcane, but bacterial contamination decreases the ethanol yields. It was shown that the biocide DesinFixTM 135 can reduce the contamination without decreasing the yeasts' viability or negatively affecting the ethanol production.

The efficacy and stability of five sanitizing agents challenged with reference microorganisms and clean area isolates / Eficácia e estabilidade de cinco agentes sanitizantes avaliados frente a microrganismos de referência e isolados de áreas limpas

The antimicrobial activity of five sanitizing agents employed in clean areas designated for the pharmaceutical manufacturing of sterile products was tested against nine microorganisms, including four microorganisms from the clean area microbiota. The method consisted of challenging 5 mL of each sanitizing agent - 70% isopropyl alcohol, 0.4% LPH®, 1.16% hydrogen peroxide, 4% hydrogen peroxide, 1% Bioper® and 5% phenol - with 0.1mL each of concentrated suspensions (105 ? 106 CFU/mL) of Staphylococcus aureus, Candida albicans, Corynebacterium sp., Micrococcus luteus, Escherichia coli, Aspergillus niger, Bacillus subtilis, Staphylococcus sp. and Bacillus sp. for 10 minutes, followed by serial dilutions and plating. The results demonstrated that the five agents were effective against S. aureus, C. albicans, Corynebacterium sp., and M. luteus. The same was true of E. coli, except that isopropyl alcohol showed low levels of inactivation. With A. niger, isopropyl alcohol, 0.4% LPH® and hydrogen peroxide were more effective and 5% phenol and 1% Bioper® less effective. 1% Bioper® and 4% hydrogen peroxide showed greater inactivation of Staphylococcus sp., Bacillus sp. and B. subtilis than the other agents. Against S. aureus, C. albicans, Corynebacterium sp. and M. luteus, 5% phenol showed similar activity to other agents, while with A. niger, B. subtilis, Staphylococcus sp. and Bacillus sp., it was similar to or less active than the other agents. It was demonstrated that two microorganisms from the clean area microbiota, Staphylococcus sp. and Bacillus sp., were the most difficult to eradicate, requiring more frequent application of hydrogen peroxide and 1% Bioper® than the other strains.

O objetivo deste estudo é avaliar a atividade antimicrobiana de cinco agentes sanitizantes empregados em áreas limpas construídas para a fabricação de produtos farmacêuticos estéreis contra nove microrganismos, incluindo quatro microrganismos oriundos da área limpa. A metodologia constituiu em desafiar 5 mL de cada agente sanitizante, álcool isopropílico 70%, LPH® 0,400%, peróxido de hidrogênio 1,160% e 4%, Bioper® 1% e fenol 5% com 0,1 mL de suspensão concentrada (105 ? 106 UFC/mL) de Staphylococcus aureus, Candida albicans, Corynebacterium sp., Micrococcus luteus, Escherichia coli, Aspergillus niger, Bacillus subtilis, Staphylococcus sp. e Bacillus sp. individualmente por 10 minutos, seguido de diluições seriadas e plaqueamento. Os resultados demonstraram que os cinco agentes sanitizantes foram efetivos contra S. aureus, C. albicans, Corynebacterium sp., e M. luteus. Os mesmos resultados foram observados com E. coli, exceto para o álcool isopropílico, que demonstrou baixos níveis de inativação. Contra A. niger, álcool isopropílico, 0.4% LPH® e peróxido de hidrogênio foram mais efetivos e fenol e Bioper® menos efetivos. Bioper® e peróxido de hidrogênio 4% demonstraram altos níveis de inativação de Staphylococcus sp., Bacillus sp. e B. subtilis quando comparados com outros agentes. Fenol demonstrou atividade antimicrobiana similar aos outros agentes contra S. aureus, C. albicans, Corynebacterium sp. e M. luteus. Contra A. niger, B. subtilis, Staphylococcus sp. e Bacillus sp., a atividade antimicrobiana do fenol foi similar ou inferior a dos outros agentes. Foi demonstrado que os microrganismos isolados da área limpa, Staphylococcus sp. e Bacillus sp., foram os que apresentaram maior dificuldade para inativar, sendo necessária a aplicação de peróxido de hidrogênio e Bioper® , com maior frequência.

Adhesion and biocides inactivation of Salmonella on stainless steel and polyethylene

The adhesion of Salmonella (S.) strains to stainless steel and polyethylene and their inactivation by biocides used in food industry was investigated. Coupons of stainless steel and polyethylene were immersed in bacterial suspensions of S. Enteritidis, S. Typhimurium, and S. Bredeney during 15, 30, and 60 minutes, and submitted to different concentrations of peracetic acid (PAA), sodium hypochlorite (NaOCl), and quaternary ammonium (Quat) sanitizers. Hydrophobicity of the surfaces was evaluated by contact angle measurements using the sessile drop method and bacterial adhesion was accompanied through bacterial counts and scanning electron microscopy (SEM). Results indicated that the three serovars of Salmonella presented similar adhesion to both materials (5.0 to 6.5 log cfu cm-2). The time of exposure did not influence the counts of adhered cells on both surfaces, however SEM revealed larger clusters of S. Enteritidis on both materials, not found for the other serovars. S. Enteritidis presented lower sessile drop angle on polyethylene, indicating hydrophilic properties of this material. The biocides were not able to inactivate all the microorganisms adhered on both surfaces. At least 1 log cfu cm-2 of all serovars tested remained viable after the exposure to different biocide concentrations. In general, higher counts of survivors were observed on polyethylene disinfected with different concentrations of biocides. S. Bredeney e S. Typhimurium were more resistant than S. Enteritidis to PAA, whilst S. Enteritidis presented smaller reduction rates to NaOCl. This last biocide was able to reduce Salmonella counts in approximately 3.0 to 4.0 log cm-2. When adhered to polyethylene, the serovars S. Typhimurium and S. Enteritidis were more resistant to Quat than S. Bredeney in all concentrations tested, and the numbers of S. Enteritidis remained almost unaltered. On stainless steel disinfected by Quat, S. Bredeney presented higher numbers of survivors.