prbA, a gene coding for an esterase hydrolyzing parabens in enterobacter cloacae and Enterobacter gergoviae strains

Microbiota analysis for risk assessment of xenobiotics: toxicomicrobiomics, incorporating the gut microbiome in the risk assessment of xenobiotics and identifying beneficial components for One Health

This work explores three areas of relevance to the gut microbiome in the context of One Health; the incorporation of the microbiome in food safety risk assessment of xenobiotics; the identification and application of beneficial microbial components to various areas under One Health, and specifically, in the context of antimicrobial resistance. We conclude that, although challenging, focusing on the microbiota resilience, function and active components, are critical for advancing the incorporation of the gut microbiome in the risk assessment of xenobiotics. Moreover, research technologies, such as toxicomicrobiomics, culturomics and genomics, especially in combination, have revealed that the human microbiota may be a promising source of beneficial taxa or other components, with the potential to metabolise and biodegrade xenobiotics. These may have possible applications in several health areas, including in animals or plants for detoxification or in the environment for bioremediation. This approach would be of particular interest for antimicrobials, with the potential to ameliorate antimicrobial resistance development. Finally, we propose that the concept of resistance to xenobiotics in the context of the gut microbiome may deserve further investigation in the pursuit of holistically elucidating their involvement in the balance between health and disease.

Incorporating the Gut Microbiome in the Risk Assessment of Xenobiotics and Identifying Beneficial Components for One Health

Three areas of relevance to the gut microbiome in the context of One Health were explored; the incorporation of the microbiome in food safety risk assessment of xenobiotics; the identification and application of beneficial microbial components to various areas under One Health, and; specifically, in the context of antimicrobial resistance. Although challenging, focusing on the microbiota resilience, function and active components is critical for advancing the incorporation of microbiome data in the risk assessment of xenobiotics. Moreover, the human microbiota may be a promising source of beneficial components, with the potential to metabolize xenobiotics. These may have possible applications in several areas, e.g., in animals or plants for detoxification or in the environment for biodegradation. This approach would be of particular interest for antimicrobials, with the potential to ameliorate antimicrobial resistance development. Finally, the concept of resistance to xenobiotics in the context of the gut microbiome may deserve further investigation.

In vitro study to evaluate the antimicrobial activity of various multifunctional cosmetic ingredients and chlorphenesin on bacterial species at risk in the cosmetic industry

AIMS

We evaluated the activity of the preservative chlorphenesin and of four antimicrobial cosmetic multifunctional ingredients against various strains of gram-negative and gram-positive human opportunistic pathogens.

METHODS AND RESULTS

Growth kinetics, modelling growth parameters and statistical analyses enabled comparing bacterial behaviour in the presence and in the absence of the compound. Whatever compound tested (i.e. chlorphenesin, phenylpropanol, hexanediol, ethylhexylglycerin, hydroxyacetophenone) and strain origin (i.e. clinical versus industrial), the growth of 42 strains belonging to Acinetobacter spp., Burkholderia cepacia complex and Stenotrophomonas maltophilia, was totally inhibited. On the opposite all of the P. aeruginosa strains (n = 13) as well as 4 and 6 out of 10 strains of Pluralibacter gergoviae grew in the presence of chlorphenesin and ethylhexylglycerin, respectively. Some P. gergoviae and Staphylococcus hominis strains withstand hydroxyacetophenone. Within a species, the different strains show variable latency phase, growth rate (r) and carrying capacity (K). They can be similar, lower or higher than those measured in control conditions.

CONCLUSIONS

Data showed differences in the antimicrobial activity of compounds. Upon exposure, strains differed in their behaviour between and within species. Whatever species and strains, compound sensitivity could not be related to antibiotic resistance.

SIGNIFICANCE AND IMPACT OF THE STUDY

Most multifunctional ingredients showed significant antimicrobial properties against the wide panel of species and strains evaluated. This will help adjusting preservation strategies in the cosmetic industry.

Salicylate UV-Filters in Sunscreen Formulations Compromise the Preservative System Efficacy against Pseudomonas aeruginosa and Burkholderia cepacia

Contamination of personal-care products are a serious health concern and therefore, preservative solutions are necessary for the costumers’ safety. High sun protection factor (SPF) sunscreen formulations are known to be difficult to preserve, due to their high ratio of organic phase containing the UV-filters. Salicylate esters such as octyl salicylate (OS) and homosalate (HS) are among the most common UV-filters currently used in the market, and can undergo hydrolysis by esterase molecules produced by contaminant microorganisms. The hydrolysis product, salicylic acid (SA) can be assimilated by certain bacteria that contain the chorismate pathway, in which its final product is pyochelin, an iron-chelating siderophore. Here, we show that OS and HS can compromise the preservative efficacy against two pathogenic important bacteria, Pseudomonas aeruginosa and Burkholderia cepacia. Challenge tests of formulations containing the UV-filters demonstrated that only bacteria with the chorismate pathway failed to be eradicated by the preservation system. mRNA expression levels of the bacterial pchD gene, which metabolizes SA to produce pyochelin, indicate a significant increase that was in correlation with increasing concentrations of both OS and HS. These data suggest that certain UV-filters can provide a source for bacterial resistance against common preservatives in sunscreen formulations.

Microbiological Safety of Non-Food Products: What Can We Learn from the RAPEX Database?

For consumer protection across borders, the European Union has established the rapid alert system for dangerous non-food products (RAPEX), with the overarching goal of preventing or limiting the sale and use of non-food products that present a serious risk for the health and safety of consumers. In our study, we comprehensively analyzed RAPEX notifications associated with products posing a microbiological risk from 2005 through 2017. Additional information was retrieved from national laboratory reports. A total of 243 microbiologically harmful consumer products triggered notifications in 23 out of 31 participating countries. About half of the products were reported by Spain, Germany, and Italy. Notifications mainly included contaminated toys, cosmetics, and chemical products. Depending on the notifying country, measures taken to prevent the spread of dangerous products were predominantly ordered either by public authorities or economic operators. The interval between microbiological diagnosis and the date of RAPEX notifications considerably varied between RAPEX member states, ranging between a few days and 82 weeks. The nature and extent of RAPEX usage substantially differed among member states, calling for harmonization and optimization. Slight modifications to RAPEX could help to systematically record microbiological hazards, which may improve the assessment of potential health risks due to contaminated non-food products.

Genomic Analysis of Microbulbifer sp. Strain A4B-17 and the Characterization of Its Metabolic Pathways for 4-Hydroxybenzoic Acid Synthesis

The marine bacterium Microbulbifer sp. A4B-17 produces secondary metabolites such as 4-hydroxybenzoic acid (4HBA) and esters of 4HBA (parabens). 4HBA is a useful material in the synthesis of the liquid crystal. Parabens are man-made compounds that have been extensively used since the 1920s in the cosmetic, pharmaceutical, and food industries for their effective antimicrobial activity. In this study, we completed the sequencing and annotation of the A4B-17 strain genome and found all genes for glucose utilization and 4HBA biosynthesis. Strain A4B-17 uses the Embden-Meyerhof-Parnas (EMP), hexose monophosphate (HMP), and Entner-Doudoroff (ED) pathways to utilize glucose. Other sugars such as fructose, sucrose, xylose, arabinose, galactose, mannitol, and glycerol supported cell growth and 4HBA synthesis. Reverse transcriptional analysis confirmed that the key genes involved in the glucose metabolism were functional. Paraben concentrations were proportionally increased by adding alcohols to the culture medium, indicating that strain A4B-17 synthesizes the 4HBA and the alcohols separately and an esterification reaction between them is responsible for the paraben synthesis. A gene that codes for a carboxylesterase was proposed to catalyze this reaction. The temperature and NaCl concentration for optimal growth were determined to be 35°C and 22.8 g/L.

Microbial Stability of Pharmaceutical and Cosmetic Products

This review gives a brief overview about microbial contamination in pharmaceutical products. We discuss the distribution and potential sources of microorganisms in different areas, ranging from manufacturing sites, pharmacy stores, hospitals, to the post-market phase. We also discuss the factors that affect microbial contamination in popular dosage forms (e.g., tablets, sterile products, cosmetics). When these products are contaminated, the microorganisms can cause changes. The effects range from mild changes (e.g., discoloration, texture alteration) to severe effects (e.g., changes in activities, toxicity). The most common method for countering microbial contamination is the use of preservatives. We review some frequently used preservatives, and we describe the mechanisms by which microorganisms develop resistance to these preservatives. Finally, because preservatives are inherently toxic, we review the efforts of researchers to utilize water activity and other non-preservative approaches to combat microbial contamination.

Co-metabolic enhancement of organic removal from waste water in the presence of high levels of alkyl paraben constituents of cosmetic and personal care products

The enhanced removal of organic material from municipal waste water containing 50 mg/L of chemical oxygen demand and a given amount of alkyl paraben using a biofilm system was investigated. The parabens used were methyl, ethyl, and propyl paraben. The experiments were conducted at influent paraben concentrations of 10 and 50 mg/L. The influent pH was measured around 4.6 because of paraben hydrolysis. The effluent pH increased due to hydrogen consumption and small molecular acid generation. The higher removal rates were observed for the paraben with longer alkyl chains, which were more hydrophobic and capable of penetrating into microbial cells. The co-existing organic constituents in municipal waste water were found to be competitive with paraben molecules for microbial degradation at low paraben loading (i.e., 10 mg/L). Instead, the co-metabolic effect was observed at a higher paraben loading (i.e., 50 mg/L) due to more active enzymatic catalysis, implying the possible enhancement or organic removal in the presence of high levels of parabens. The difference in BOD and TOC removing ratios for parabens decreased with increasing HRT, implying their better mineralization than that of municipal organic constituents. This was because the microbial organism became more adapted to the reacting system with longer HRT, and more oxygenase was produced to facilitate the catechol formation and ring-opening reactions, causing apparent enhancement in mineralization.

Burkholderia cepaciaInfections Associated With Intrinsically Contaminated Ultrasound Gel: The Role of Microbial Degradation of Parabens

Objective:

To describe an outbreak of serious nosocomialBurkholderia cepaciainfections occurring after transrectal prostate biopsy associated with ultrasound gel intrinsically contaminated with paraben-degrading microorganisms.

Methods:

A retrospective chart review prompted by a blood culture isolate ofB, cepacia.Identification of microorganisms in ultrasound gel in two Canadian centers and characterization by pulsed-field gel electrophoresis and assays for paraben degradation.

Setting:

Two Canadian university-affiliated, tertiary-care centers in Newfoundland and Alberta.

Results:

Six seriousB. cepaciainfections were identified at the two centers. Isolates ofB. cepaciarecovered from the blood of patients from both centers and the ultrasound gel used during the procedures were identical, confirming intrinsic contamination. Strains ofEnterobacter cloacaeisolated from ultrasound gel at the two centers were also identical. The ability to degrade parabens was proven for bothB. cepaciaandE. cloacaestrains recovered from the ultrasound gel.

Conclusions:

Ultrasound gel is a potential source of infection. Contamination occurs at the time of manufacture, with organisms that degrade parabens, which are commonly used as stabilizing agents. There are far-reaching implications for the infection control community.

Investigation of current infection-control practices for ultrasound coupling gel: a survey, microbiological analysis, and examination of practice patterns

BACKGROUND AND OBJECTIVES

Ultrasound coupling gel may serve as a vector for the spread of bacteria and has been the causative agent for significant health care-associated infections. The purpose of this study was to document existing infection-control procedures and level of contamination present within nonsterile ultrasound gel from several clinical departments at a single institution. A second purpose was to examine the effectiveness of clinician education and manufacturer-based ultrasound additives on ultrasound gel contamination and in vitro bacterial proliferation, respectively.

METHODS

Compliance with Health Canada recommended infection-control policies were determined by survey. Contamination of in-use ultrasound gel bottles was determined by inspecting cultures after 72 hours of incubation. After infection-control education, a 28-day interval assessment was used to examine contamination rates in newly provided ultrasound gel. The ability of ultrasound gel containing parabens to prevent bacterial growth was examined in cultures grown with and without ultrasound gel.

RESULTS

Practitioners were not compliant with Health Canada recommendations, but the baseline ultrasound gel contamination rate within these departments was only 2.5%. Education in infection control did not improve the contamination rate over 28 days. Contamination was discovered in ultrasound gel supplied directly from the manufacturer. Ultrasound gel suppressed but did not prevent bacterial growth in a species- and time-specific manner.

CONCLUSIONS

The source of contamination for in-use ultrasound gel may be of manufacturer or human origin. Because additives to the ultrasound gel are not bactericidal, sterile ultrasound gel should be used for invasive and high-risk cases, and improving infection-control policies is warranted.

A novel Aspergillus oryzae esterase that hydrolyzes 4-hydroxybenzoic acid esters

In this study we report the biochemical characterization of a hypothetical protein from Aspergillus oryzae exhibiting sequence identity with feruloyl esterase and tannase from the genus Aspergillus. The purified recombinant protein showed a hydrolytic activity toward the ethyl, propyl, or butyl esters of 4-hydroxybenzoic acid, but did not show feruloyl esterase or tannase activity. Finally, the enzyme decreased the antimicrobial activity of parabens against A. oryzae via hydrolysis of the ester bond present in butyl 4-hydroxybenzoic acid.

Enterobacter gergoviae and the prevalence of efflux in parabens resistance

OBJECTIVES

In order to characterize the mechanism involved in parabens resistance, we studied 13 Enterobacter gergoviae collected from diverse cosmetic formulations containing parabens as preservatives and 10 isolates from clinical or industrial sources.

METHODS

RAPD and ERIC-PCR were employed and compared for the epidemiological typing. To study antibiotic and paraben susceptibility, the standard disc diffusion method and the 2-fold dilution method in Luria-Bertani medium were used. Characterization of porins was performed using immunodetection with polyclonal antibodies. Resistance mechanisms against parabens membrane permeabilization were evaluated by measuring K(+) efflux using a specific electrode. mar regulon identification and comparison were carried out.

RESULTS

Epidemiological typing confirmed that most of the cosmetic formulations were contaminated by unrelated strains. All of the E. gergoviae strains presented high methylparaben MICs, ranging from 1 to 3.8 g/L, values that were 2-5 times higher than for Escherichia coli or Enterobacter aerogenes, even in strains overexpressing MarA. These MICs decreased in the presence of phenylalanine arginine beta-naphthylamide, pinpointing efflux as a major mechanism of parabens resistance even in E. gergoviae clinical strains.

CONCLUSIONS

This is the first report showing the role of active efflux in the parabens resistance in E. gergoviae, a mechanism that may explain its frequent isolation in parabens-containing cosmetics compared with other enterobacterial species. Paraben efflux seems to be regulated by a mar-independent process in E. gergoviae.

Purification and characterization of PrbA, a new esterase from Enterobacter cloacae hydrolyzing the esters of 4-hydroxybenzoic acid (parabens)

The esterase PrbA from Enterobacter cloacae strain EM has previously been shown to confer additional resistance to the esters of 4-hydroxybenzoic acid (parabens) to two species of Enterobacter. The PrbA protein has been purified from E. cloacae strain EM using a three-step protocol resulting in a 60-fold increase in specific activity. The molecular mass of the mature enzyme was determined to be 54,619 +/- 1 Da by mass spectrometry. It is highly active against a series of parabens with alkyl groups ranging from methyl to butyl, with K(m) and V(max) values ranging from 0.45 to 0.88 mM and 0.031 to 0.15 mM/min, respectively. The K(m) and V(max) values for p-nitrophenyl acetate were 3.7 mM and 0.051 mM/min. PrbA hydrolyzed a variety of structurally analogous compounds, with activities larger than 20% relative to propyl paraben for methyl 3-hydroxybenzoate, methyl 4-aminobenzoate, or methyl vanillate. The enzyme showed optimum activity at 31 degrees C and at pH 7.0. PrbA was able to transesterify parabens with alcohols of increasing chain length from methanol to n-butanol, achieving 64% transesterification of 0.5 mm propyl paraben with 5% methanol within 2 h. PrbA was inhibited by 1-chloro-3-tosylamido-4-phenyl-2-butanone and 1-chloro-3-tosylamido-7-amino-2-heptanone (TLCK), with K(i) values of 0.29 and 0.20 mM, respectively, and was irreversibly inhibited by Diisopropyl fluorophosphate (DFP) or diethyl pyrocarbonate. The stoichiometry of addition of DFP to the enzyme was 1:1 and only 1 TLCK molecule was found in TLCK-modified enzyme, as measured by mass spectrometry. Analysis of the tryptic digest of the DFP-modified PrbA demonstrated that the addition of a DFP molecule occurred at Ser-189, indicating the location of the active serine.