Guilherme Schneider,Leticia Genova Vieira,Herica Emilia Félix de Carvalho,Álvaro Francisco Lopes de Sousa,Evandro Watanabe,Denise de Andrade,Renata Cristina de Campos Pereira Silveira
Textiles impregnated with antimicrobial substances in healthcare services: systematic review
textiles,antimicrobial agents,health services,biosafety,infection control
Background Antimicrobial textiles have proved to be a promising biosafety strategy. Thus, the current study was focused on identifying which antimicrobial substances impregnated in textiles used in healthcare services confer efficacy in reducing the microbial load present in these textiles and/or the Healthcare-Associated Infection (HAI) rates, when compared to conventional textiles. Methods A systematic review of intervention studies using MEDLINE via the PubMed portal, EMBASE, CINAHL, Web of Science, Scopus, Google Scholar and medRxiv. The studies identified were selected according to eligibility criteria and submitted to data extraction and methodological quality evaluation through Joanna Briggs Institute specific tools. The outcomes were synthesized qualitatively. Results 23 studies were selected to comprise the final sample, in which antimicrobial textiles were used by hospitalized patients, by health professionals during work shifts and in inanimate healthcare environments. Conclusions Copper, silver, zinc oxide, titanium and silver-doped titanium impregnated in textiles used by patients confer efficacy in reducing the microbial load of these textiles and/or the HAI rates. Quaternary ammonium, chlorhexidine, silver and copper together, quaternary ammonium, alcohols and isothiazolone derivatives together, chitosan and dimethylol dimethyl hydantoin together, all impregnated in textiles used by health professionals confer efficacy in reducing the microbial load of these textiles. Quaternary ammonium impregnated in textiles used in inanimate healthcare environments confers efficacy in reducing the microbial load of these textiles.
Textiles impregnated with antimicrobial substances in healthcare services: systematic review

Antimicrobial textiles have proved to be a promising biosafety strategy. Thus, the current study was focused on identifying which antimicrobial substances impregnated in textiles used in healthcare services confer efficacy in reducing the microbial load present in these textiles and/or the Healthcare-Associated Infection (HAI) rates, when compared to conventional textiles.

A systematic review of intervention studies using MEDLINE via the PubMed portal, EMBASE, CINAHL, Web of Science, Scopus, Google Scholar and medRxiv. The studies identified were selected according to eligibility criteria and submitted to data extraction and methodological quality evaluation through Joanna Briggs Institute specific tools. The outcomes were synthesized qualitatively.

23 studies were selected to comprise the final sample, in which antimicrobial textiles were used by hospitalized patients, by health professionals during work shifts and in inanimate healthcare environments.

Copper, silver, zinc oxide, titanium and silver-doped titanium impregnated in textiles used by patients confer efficacy in reducing the microbial load of these textiles and/or the HAI rates. Quaternary ammonium, chlorhexidine, silver and copper together, quaternary ammonium, alcohols and isothiazolone derivatives together, chitosan and dimethylol dimethyl hydantoin together, all impregnated in textiles used by health professionals confer efficacy in reducing the microbial load of these textiles. Quaternary ammonium impregnated in textiles used in inanimate healthcare environments confers efficacy in reducing the microbial load of these textiles.

- Textiles impregnated with antimicrobial substances can be used in health services. - Antimicrobial textiles provide biosafety to patients and health professionals. - Compared to conventional textiles, antimicrobial textiles have lower microbial load. - Antimicrobial textiles can be a viable alternative to reduce HAIs.

The patient's surroundings can be considered as sources of microbial contamination due to factors such as high frequency of touch and mutual contact by health professionals during care activities, as well as by the patients themselves and their visitors, favoring cross-contamination (1). In this context, the textile materials found in healthcare services, whether in inanimate environments in general, in the professionals' uniforms or in clothing and bed linen used by the patients during the hospitalization regime, are not exempt from microbial contamination, proliferation and dissemination (2). For example, the scientific literature points to the wide microbial contamination of privacy curtains in clinical settings, (3, 4) as well as of the health professionals' white coats, (5, 6) in addition to the clothing and bed linen used by the patients during the hospitalization period (7, 8). There are also possible indications for relationships of microbial contamination in different textile materials used by the patients and health professionals and in the inanimate healthcare environments, with occurrence of Healthcare-Associated Infections (HAIs) and infectious outbreaks in hospital services (9, 10). Thus, there is an interest in textile impregnation, in order to provide those materials with antimicrobial properties that tend to minimize contamination and microbial load, thus reducing the biological risks. This process can be basically performed through two different methods, namely: previous incorporation of the antimicrobial agent into the textile fiber matrix, into the spinning process; or coating, from specific techniques that promote adhesion of the antimicrobial agent to the textile substrate during the finishing process (11). The substances with antimicrobial properties used in impregnation of textiles can be both organic (such as quaternary ammonium compounds, halamines, polybiguanides, triclosan, chitosan and bioactive plant-based compounds) and inorganic (such as nanoparticles and metal oxides) (12). Despite being a promising strategy, wide implementation of these antimicrobial textiles in healthcare services should be, above all, cautious, as the scientific literature on the theme points to important contradictions in laboratory studies regarding the results in relation to microbial load reduction, including drug-resistant microorganisms, (13, 14) as well as cytotoxicity (15, 16). In addition to that, in real healthcare conditions, clinical studies with different use configurations of textiles impregnated with antimicrobials employed by professionals or hospitalized patients collectively obtained intriguing results, being considered unsatisfactory regarding reduction of the microbial load on health professionals' clothes, but satisfactory in relation to the reduction of HAIs, respectively (17). Furthermore, the potential for induction of microbial resistance to the substances impregnated in these textiles should be considered, mainly when the antimicrobial and/or impregnation method selected favor controlled release mechanisms and, consequently, considerable leaching in a wet medium. This gradual and persistent release is followed by a reduction of the antimicrobial concentration in the textile at levels below the Minimum Inhibitory Concentration (MIC), that is, the antimicrobial efficacy limit that can induce development of microbial resistance (12). It should also be considered that there are yet no definitive answers as to the potential of certain substances impregnated in textiles to promote selection of microorganisms resistant to other antimicrobials, even pharmacological ones (18), which increases the risk for the advent of cross-resistance, co-resistance and resistance by co-regulation to antimicrobials (19). In this context, the current study focused on identifying which antimicrobial substances impregnated in textiles used in healthcare services confer efficacy in reducing the microbial load present in these textiles and/or the HAI rates, when compared to conventional textiles.

This study is a systematic review of the scientific literature, focused on the research studies where a given intervention was implemented in healthcare services, as well as evaluation of its effectiveness (20) reported in accordance with the guidelines proposed by the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) (21).

The systematic review protocol was registered in the Open Science Framework (OSF) platform, under DOI 10.17605/OSF.IO/M685U on October 21, 2021, and can be consulted in full via the following access link: https://osf.io/m685u.

The research question was prepared with the help of the PICO strategy, so that: (P)roblem: microbial load present in the textiles used by patients and health professionals and in the inanimate healthcare environments, and HAI rates; (I)ntervention: textiles impregnated with antimicrobial substances; (C)omparison: conventional textiles (devoid of any type of impregnation); (O)utcome: reduction of the microbial load present in the textiles used by patients and health professionals and in inanimate healthcare environments, and/or reduction of the HAI rates. Thus, the following research question was defined: “Which are the antimicrobial substances impregnated in textiles used by patients and health professionals and in inanimate healthcare environments, which confer efficacy in reducing the microbial load present in these textiles and/or the HAI rates, when compared to conventional textiles?”.

The adverse events (cutaneous signs and symptoms) presented by the patients and/or health professionals after using textiles impregnated with antimicrobial substances, according to each type of textile material and antimicrobial substance, were considered as additional outcomes to be determined and synthesized in this review.

Among the eligibility criteria, the following inclusion criteria were considered: primary studies with an intervention design (clinical trials and quasi-experimental studies) that addressed the use of textiles impregnated with antimicrobial substances in healthcare services, quantitatively evaluating variation of the microbial load present in these textiles and/or of the HAI rates (by means of a theoretical framework and/or indicators), according to their use. In general, the studies on this theme developed under real healthcare conditions do not present details of how the method to manufacture/impregnate the textiles with antimicrobials took place. As a result, it was agreed to adopt as eligible those studies in which the health institutions themselves replaced their conventional textiles (devoid of any type of impregnation) by impregnated textiles/antimicrobials, as well as those where the researchers reported the supply of impregnated/antimicrobial textiles for the health services. In addition, in view of the objectives proposed, it is also noted that the only studies that were considered eligible were those that specified the antimicrobial substances (or at least one of those substances) impregnated in the textiles, as well as their applicability with regard to using them in inanimate healthcare environments, whether by health professionals during care activities and/or by patients during the hospitalization period. As for the exclusion criteria, the studies conducted under the following use configurations of the antimicrobial-impregnated textiles were considered ineligible: Use by patients during the hospitalization period: impregnated/antimicrobial textiles for personal hygiene care (such as cloths impregnated for antisepsis and bathing, as well as impregnated diapers and tampons), dressings (such as impregnated gauze for wound covering), or adjuvant treatment of skin tissue disorders such as atopic dermatitis; Use by health professionals during their respective work shifts: impregnated/antimicrobial textiles such as Personal Protective Equipment (PPE) directed to the precaution regarding droplets or aerosols (such as impregnated facial protection masks), or for specific healthcare interventions (such as aprons and impregnated incision fields for use in surgical procedures); Use in inanimate healthcare environment: impregnated/ antimicrobial textiles for performing environmental hygiene procedures (such as impregnated cloths for disinfection of surfaces). In addition, once again based on the objectives proposed, the studies considered eligible were those where concomitant use of other antimicrobial surfaces took place, in addition to the intervention of interest (impregnated/antimicrobial textiles) in the health service; as well as those that do not present sufficient information/data for characterization and analysis of the methodological quality/risk of bias. Finally, materials published on the theme such as editorials, letters to the editor, books, book chapters, theses, dissertations and abstracts presented in scientific events were considered ineligible.

The information sources consulted were the following databases: Medical Literature Analysis and Retrieval System Online (MEDLINE) via the PubMed portal, Excerpta Medica DataBase (EMBASE), Cumulative Index to Nursing and Allied Health Literature (CINAHL) via the EBSCOhost platform, Web of Science and Scopus. In addition, the Gray Literature was explored through Google Scholar (which also allows retrieving studies indexed in the databases searched), as well as the medRxiv preprint database. The search strategy was formulated through the combination of controlled descriptors and keywords related to the theme of interest, being adapted to each of the aforementioned information sources, that is, respecting their particularities. It is noteworthy that, in order to identify the studies referring to the research question in the most comprehensive possible way, no filters related to publication period and language were used. In the exceptional case of Google Scholar, as it is a search engine that tends to identify endless results, it was decided to delimit the process corresponding to analysis and selection of studies that met the eligibility criteria only to the first 100 results identified in order of relevance. Thus, so as to avoid potential losses in the identification of eligible studies resulting from this process, four different search strategies were structured and applied in this search platform (Supplementary material 1). Additionally, a manual search was conducted for other studies that met the previously established eligibility criteria, analyzing the lists of references cited by the studies identified in the databases and in the Gray Literature, which were considered eligible in the analysis and selection process.

Initially, all 2,026 records identified in the databases and in the Gray Literature were imported into the EndNote Basic® software (Clarivate Analytics), a reference manager where 653 duplicates were removed, totaling 1,373 records screened that were subsequently imported into the Rayyan® software (Qatar Computing Research Institute), where the process to analyze and select the studies based on the eligibility criteria was conducted. Independently and blindly, two researchers conducted the process for the analysis and selection of the studies, in two phases: in phase 1, after reading the titles and abstracts of all 1,373 records screened, 1,322 were excluded for not responding to the review objectives. Consequently, 51 reports progressed to Phase 2 where, after full-text reading, 29 were excluded due to the following reasons: Reason 1: Material on the theme published, such as editorial, letter to the editor, book, book chapter, thesis, dissertation or abstract presented in a scientific event, which resulted in the exclusion of 16 reports; Reason 2: The study does not specify the antimicrobial substance impregnated in the textiles, which resulted in the exclusion of 3 reports; Reason 3: The study does not specify applicability of the antimicrobial textiles in the health service, which resulted in the exclusion of 2 reports; Reason 4: The study does not assess microbial load in the antimicrobial textiles and/or the HAI rates by means of a theoretical framework or indicators, which resulted in the exclusion of 1 report; Reason 5: In addition to the intervention of interest (antimicrobial textiles), the study addresses concomitant use of other antimicrobial surfaces in the health service, which resulted in the exclusion of 6 reports; Reason 6: The study does not present sufficient information/data for characterization and analysis of methodological quality/risk of bias, which resulted in the exclusion of 1 report. Thus, 22 studies were considered eligible for inclusion in this review. Complementing this sample, the lists of references cited by all 22 studies were examined, which resulted in the identification of another 3 potentially eligible records (after reading titles and abstracts), from which 2 reports were excluded (after full-text reading) due to the following reasons: Reason 5: In addition to the intervention of interest (antimicrobial textiles), the study addresses concomitant use of other antimicrobial surfaces in the health service, which resulted in the exclusion of 1 reports; Reason 7: The study investigates a given non-textile antimicrobial material fixed to conventional textiles (non-antimicrobial), which resulted in the exclusion of 1 report. Thus, only 1 study was considered eligible through this process, resulting in a final sample of 23 studies included in this knowledge synthesis. This process can be visualized with more details in Figure 1 below. Any and all possible disagreements in this process of analysis and selection of studies were resolved by a third researcher with expertise in the theme of interest. The reports excluded (after full-text reading) were referenced and presented together with their respective reasons for exclusion in Supplementary material 2.

Once again independently and blindly, two researchers conducted the process for extracting the following data from the studies selected: Characteristics of the study: design, sample size, locus/country in which the study was developed and follow-up period; Characteristics of the intervention: types of textiles, antimicrobial substances impregnated in the textiles, applicability of these textiles in health services, and hygiene settings of these textiles; Assessment method of the microbial load in the textiles, HAI rates and adverse events; Results of microbial load present in the textiles, HAI rates and adverse events. Due to the different and extensive microbiological assessments performed in the studies selected, it was decided to prioritize the extraction of non-specific microbial load data in the conventional and impregnated/antimicrobial textiles before and after their use, as presented by the studies. In the studies that did not present these data, it was agreed to prioritize extraction of the specific microbial load data or microbial load in each sampled area of the textiles before and after their use, as presented. Regarding assessment of the HAI rates, it was agreed to prioritize extraction of the non-specific HAI data and indicators before and after using conventional and impregnated/antimicrobial textiles, as presented by the studies. In the studies that did not present these data, it was agreed to prioritize extraction of the specific HAI data in relation to the etiological agents before and after using conventional and impregnated/antimicrobial textiles, as presented. After completing this process, both researchers cross-checked the data retrieved, and any and all divergences were resolved by discussion and mutual agreement. In the event of any disagreement, a third researcher with expertise in the theme of interest was available for consultation and final decision-making. Subsequently, the data retrieved referring to each of the studies selected were recorded in study characterization charts, namely: Characterization chart of studies in which the textiles impregnated with antimicrobials were used by patients during the hospitalization period; Characterization chart of studies in which the textiles impregnated with antimicrobials were used by health professionals during their respective work shifts; Characterization chart of studies in which the textiles impregnated with antimicrobials were used in inanimate healthcare environments.

The methodological quality assessment (risk of bias) corresponding to each of the studies selected was performed through specific and appropriate Critical Appraisal Tools for each study design, made available by the Joanna Briggs Institute (JBI) (20). These tools consist of different topics, which are filled out with the “Yes”, “No”, “Unclear” or “Not applicable” answers, according to the diverse information presented by the studies. Classification of the methodological quality of the studies is based on the percentage of “Yes” answers obtained for the topics that comprise the tool used, and it is the researchers themselves who previously define how the scoring system (cutoff points/percentages) will be constituted to classify methodological quality (20). In this review, it was defined that, regardless of the tool, the topics that obtained the “Not applicable” answer would not be considered for calculation of the percentage of “Yes” answers, and that the methodological quality of the studies would be classified according to the following scoring system: Low methodological quality (high risk of bias): if the study evaluated reaches <50% of “Yes” answers to the topics of the tool used; Moderate methodological quality (moderate risk of bias): if the study evaluated reaches 50% to 74% of “Yes” answers to the topics of the tool used; High methodological quality (low risk of bias): if the study evaluated reaches 75% or more “Yes” answers to the topics of the tool used. This process to assess the methodological quality of the studies selected was also carried out by two researchers, independently and blindly, and a third researcher with expertise in these tools was called upon to resolve any and all divergences.

The synthesis of the results was presented qualitatively, describing in general the data referring to the microbial load present in the textiles, the HAI rates and the adverse events presented by the patients and health professionals, according to the antimicrobial substances impregnated in the textiles used and their applicability in healthcare services, also considering the methodological quality of the studies selected. It was not possible to perform a quantitative (statistical) synthesis of the results due to the marked heterogeneity of methodological configurations across the studies selected, as well as to their methodological quality.

Due to the impossibility of performing a quantitative (statistical) synthesis of the results, it was decided not to assess the certainty of the synthesized evidence (qualitatively) through the Grading of Recommendations Assessment, Development and Evaluation (GRADE) system (22), as previously planned in the systematic review protocol.

The 23 studies selected to comprise this systematic review, in which the textiles impregnated with antimicrobial substances were used by patients during the hospitalization period, by health professionals during their respective work shifts, and in inanimate healthcare environments, were characterized in Charts 1–3, respectively. Charts 4, 5 present the methodological quality assessment (risk of bias) corresponding to these studies, according to the specific tools for each type of design, made available by the JBI. Among the 10 studies in which the textiles impregnated with antimicrobial substances were used by patients during the hospitalization period, five and four studies, respectively, only evaluated the HAI rates and the microbial load in these textiles, while only one study evaluated both the HAI rates and the microbial load in these textiles (Chart 1). In five of the six studies in which copper was the impregnating substance of the textiles used by the patients, there was efficacy in reducing the microbial load of these textiles and/or the HAI rates, when compared to conventional textiles (even if this difference was not always considered statistically significant), and their methodological quality was considered moderate (moderate risk of bias) (26, 32) or high (low risk of bias) (23, 27, 31) while the only study conducted under these same configurations that did not result in efficacy in reducing the HAI rates presented low methodological quality (high risk of bias) (25). In the two studies where silver was the impregnating substance of the textiles used by the patients, there was efficacy in reducing the microbial load of these textiles and the HAI rates, when compared to conventional textiles, and their methodological quality was considered moderate (moderate risk of bias) (30) and high (low risk of bias) (24). As for the other two studies in which zinc oxide, (29) and titanium nanoparticles and silver-doped titanium nanoparticles (together), (28) were the impregnating substances of the textiles used by the patients, there was efficacy in reducing the microbial load of these textiles, when compared to conventional textiles (even if the statistical significance was not always evaluated or presented), and their methodological quality was considered moderate (moderate risk of bias). Among these 10 studies in which the textiles impregnated with antimicrobial substances were used by the patients during the hospitalization period, only three evaluated the occurrence of adverse events presented by the participants. No adverse events were identified in two studies where copper was the impregnating substance of the textiles used by the patients (27, 32). In the study where zinc oxide was the impregnating substance of the textiles used by the patients, itching, erythema and rash were identified in the participants belonging to the control and intervention groups (29). All 10 studies in which the textiles impregnated with antimicrobial substances were used by health professionals during their respective work shifts only evaluated the microbial load in these textiles (Chart 2). In three of the five studies where silver was the impregnating substance for the textiles used by health professionals, there was no efficacy in reducing the microbial load of these textiles, when compared to conventional textiles, and their methodological quality was considered moderate (moderate risk of bias) (34, 38, 41). while the other two studies conducted under these same configurations that resulted in efficacy in reducing the microbial load of these textiles when compared to conventional textiles (even if this difference was not always considered statistically significant, or even if the statistical significance was not always evaluated or presented), had low methodological quality (high risk of bias) (35, 36). In the two studies where quaternary ammonium was the impregnating substance for the textiles used by health professionals, there was efficacy in reducing the microbial load of these textiles, when compared to conventional textiles (even if this difference was not always considered statistically significant), and their methodological quality was considered moderate (moderate risk of bias) (34, 39). In the study where chlorhexidine was the impregnating substance of the textiles used by health professionals, there was efficacy in reducing the microbial load of these textiles, when compared to conventional textiles, and its methodological quality was considered moderate (moderate risk of bias) (33). In the three studies where silver and copper (together), (42) quaternary ammonium, alcohols and isothiazolone derivatives (together), (40) and chitosan and dimethylol dimethyl hydantoin (together), (37) were the impregnation substances of the textiles used by health professionals, there was efficacy in reducing the microbial load of these textiles, when compared to conventional textiles (even if this difference was not always was considered statistically significant), and their methodological quality was considered moderate (moderate risk of bias). Among these 10 studies in which the textiles impregnated with antimicrobial substances were used by health professionals during their respective work shifts, only four evaluated the occurrence of adverse events presented by the participants. In the studies where chlorhexidine, (33) and chitosan and dimethylol dimethyl hydantoin (together), (37) were the impregnating substances in the textiles used by health professionals, no adverse events were identified (in the participants of the interventions of interest). In two studies where silver was the substance employed to impregnate the textiles used by health professionals, itching and erythema were identified in participants from the intervention group (38), in addition to itching in participants belonging to the control and intervention groups and erythema or rash in those from the intervention group (34). In a study where quaternary ammonium was the substance employed to impregnate the textiles used by health professionals, itching was identified in participants belonging to the control and intervention groups, and erythema or skin rash in those from the intervention group (34). All three studies where the textiles impregnated with antimicrobial substances were used in inanimate healthcare environments only assessed the microbial load in these textiles (Chart 3). In one of the two studies where silver was the substance employed to impregnate the textiles used in inanimate healthcare environments, there was no control group or period that allowed comparing results, (45) whereas, in the other study there was no efficacy in reducing the microbial load of these textiles, when compared to conventional textiles (44), with the methodological quality of both considered as moderate (moderate risk of bias). In the study where halamine was the substance employed to impregnate the textiles used in inanimate healthcare environments, there was efficacy in reducing the microbial load of these textiles, when compared to conventional textiles (even though this difference was not always considered statistically significant) and its methodological quality was considered low (high risk of bias) (43). In the study where quaternary ammonium was the substance employed to impregnate the textiles used in inanimate healthcare environments, there was efficacy in reducing the microbial load of these textiles, when compared to conventional textiles, and its methodological quality was considered moderate (moderate risk of bias) (44). In these three studies where the textiles impregnated with antimicrobial substances were used in inanimate healthcare environments, no assessments of the occurrence of adverse events in individuals (patients and health professionals) who came into contact with these textiles were performed.

Development of this systematic review allowed evidencing that the composition of the scientific literature on textiles impregnated with antimicrobial substances is massively based on laboratory experiments, especially in vitro, and that there are still few studies conducted in real healthcare conditions, among which only a small percentage was able to recruit significant sample sizes for their respective control and intervention groups/periods, took place in multiple centers, or conducted the control and intervention experimental analyses concomitantly or in parallel follow-up periods, allowing extrapolation of the results to other similar contexts. With regard to the methodological configurations of the studies selected to comprise this review, it is evidenced how many possibilities there are for combinations between the independent and dependent variables. The independent variables mainly refer to the types of textiles, antimicrobial substances and applicability of the impregnated/antimicrobial textiles in health services. As for the dependent variables, they refer to possible analyses related to microbial contamination in the textiles and to the HAI rates. In relation to the independent variables, due to the multiple applicability possibilities of the textiles impregnated with antimicrobial substances in health services, it was agreed to subdivide the studies included in this review according to the use configurations of these textiles, so that this use could be by the patients during the hospitalization period, by the health professionals during their respective work shifts, and in inanimate healthcare environments. From the aforementioned, an important gap is highlighted in the scientific literature on the theme, which refers to the absence of studies that address concomitant use of impregnated/antimicrobial textiles by patients, by professionals and in inanimate healthcare environments. In the studies selected where the hospitalized patients used textiles impregnated with substances with antimicrobial activity (Chart 1), exclusive impregnation with heavy metals is noticed, specifically copper, silver, zinc oxide and titanium nanoparticles in an isolated manner, and silver-doped titanium nanoparticles together. In general, considering methodological quality, after use by the patients, the textiles impregnated with these substances presented lower microbial loads and/or resulted in lower HAI rates when compared to the use of conventional textiles. In the studies selected where the health professionals used textiles impregnated with substances with antimicrobial activity (Chart 2), impregnation took place with silver, quaternary ammonium and chlorhexidine in isolation; silver and copper together; quaternary ammonium, alcohols and isothiazolone derivatives together; and chitosan and dimethylol dimethyl hydantoin together. In general, considering methodological quality, after being used by health professionals, the textiles impregnated with these substances, with the exception of those impregnated with silver in isolation, presented lower microbial loads when compared to the use of conventional textiles. In the studies selected where inanimate healthcare environments were treated with textiles impregnated with substances with antimicrobial activity (Chart 3), impregnation was with silver, halamine and quaternary ammonium, in isolation. In general, considering methodological quality, after use in inanimate healthcare environments, the textiles impregnated with these substances, with the exception of those impregnated with silver alone, presented lower microbial loads when compared to the use of conventional textiles. It is also worth mentioning that, according to the critical evaluation, the study conducted under these same use and applicability configurations in which the textiles were impregnated with halamine, resulting in a lower microbial load when compared to conventional textiles, obtained low methodological quality, which renders such outcomes questionable. Heavy metals have antimicrobial properties through multiple mechanisms of action in microbial cells, namely: interference in cell wall synthesis; depolarization of the electrical potential of the plasma membrane; plasma membrane lysis; protein denaturation; and induction of oxidative stress, which can also act in synergy, potentiating antimicrobial activity (46). However, considering the methodological quality of the studies selected in which silver in isolation was impregnated in the textiles used by health professionals or allocated to inanimate healthcare environments, there is no efficacy in reducing the microbial load of these textiles when compared to unimpregnated textiles. Among the hypotheses that can explain this specific ineffectiveness, the probable overestimation of the antimicrobial effect of these textiles by health professionals stands out, mainly in studies with no blinding configurations, causing non-compliance with basic biosafety measures, for example: compromising hand hygiene, leading to more errors during the gowning and degowning processes, and even resulting in failures during decontamination of fomites and their inanimate environments, which corroborates to potentiating microbial contamination, even in the impregnated/antimicrobial textiles themselves. In addition to the mechanisms of action of the antimicrobial substances impregnated in the textiles, application of different antimicrobials in the impregnation process of the same textile material is noted as a potential perspective, aiming, through the attribution of various antimicrobial properties, to achieve maximum biostatic or biocidal efficacy and, thus, minimize any risk for the development and spread of microbial resistance. However, it can be observed that most of the clinical studies involving the use of impregnated/antimicrobial textiles are still characterized by the absence of detailed information related to the textile materials, the antimicrobial substances and the impregnation method, which hinders replication of these research studies, methodological validation in similar contexts and rapid progress in filling the gaps in this scientific field. In this context, there is also significant lack of information regarding the hygiene settings of the antimicrobial textiles when used in the clinical practice concerning the products and methods used, as well as the time interval between sanitation procedures. Thus, there is no way to accurately identify the ideal conditions for sanitizing such antimicrobial textiles when used in real healthcare circumstances, aiming to provide maximum durability of the antimicrobial effect and, mainly, at the reduction of dirt, organic matter and microbial load in these textiles. In relation to the dependent variables of interest in this systematic review, it is observed that microbiological collection on the textile surfaces can be performed through different methods, as well as the analyses related to microbial contamination, in short: specific and unspecific microbial load regarding the type(s) of microorganism(s); microbial load on certain areas of the textile surface; and microbial load before and after use in healthcare services. With regard to the HAI rates, there is also the possibility of identifying them through different methods, either by means of pre-established clinical indicators or according to a theoretical framework adopted, which are subjected to periodic updates; in addition to that, the respective analyses can refer to specific and non-specific HAIs regarding the etiological agent and the tissues, organs or physiological systems affected. Despite recognizing that the development of each and every infection is a multifactorial process due to the complexity of the epidemiological chain, there is no way to disregard microbial load as a crucial factor in this context (47, 48). For this reason, studies that involve the use of antimicrobial textiles in real healthcare conditions and assess the impacts on the HAI rates, as well as the microbial load in this textiles, are extremely valuable; however, as evidenced in the current review, there is a minimal percentage of studies that have concomitantly conducted such analyses. Among the factors of concern, the safety of using textiles impregnated with antimicrobial substances must be considered, as adverse events mainly represented by dermatological signs and symptoms can occur in patients and/or health professionals who are in continuous contact with these textiles. However, it is noted that there was no significant investigation of the adverse events presented by the participants of the studies that comprise the current review; therefore, any and all risks to human health cannot be ruled out and deserve greater attention. It is worth noting that, regardless of the antimicrobial substance impregnated in the textile material, its concentration should be seen as a fundamental part in striking a balance between protective functionality, whether biostatic or biocidal, and safety, in relation to non-induction of toxicity and occurrence of adverse events in the users (16). In addition to that, in clinical studies with no blinding settings for the participants, the nocebo effect should not be ignored, as it is possibly responsible for eventual bumps in the notification rates of self-reported adverse events. Thus, it becomes strictly necessary that, in future studies, this type of evaluation is carried out by specialized and trained professionals whenever possible, through anamnesis together with a physical examination of the patients and health professionals who make use of the impregnated/antimicrobial textiles. The environmental impacts also deserve due attention since, in the long-, medium- or even short-term, repeated decontamination procedures by washing impregnated textiles can lead to leaching of certain antimicrobials and to consequent contamination of water ecosystems (49). Thus, instead of using synthetic compounds in the textile impregnation field, natural bioactive substances with antimicrobial properties, mainly obtained from medicinal plants and other organic substrates, can serve as a safe and renewable alternative to the environment for biodegradability and sustainability reasons (50, 51). Other strategies can also be listed, such as passive coatings devoid of any antimicrobial properties, on the textile surfaces, which, despite not presenting biocidal or biostatic activity, are responsible for hindering microbial adhesion and are characterized as easily decontaminated (52). From an economic point of view, there is probable profitability of antimicrobial textiles, mainly when comparing the costs related to their acquisition to those required for the acquisition and application of other substances with antimicrobial activity, commonly used in health services, aiming to promote biosafety. The same profitability can be observed when considering the potential of antimicrobial textiles in preventing and controlling the HAI rates and, consequently, the substantial costs for the treatment of these infections, in addition to the incalculable harms related to morbidity and mortality. Undoubtedly, it is emphasized that economic modeling should be considered as an integral component of the evaluation of future clinical studies in this knowledge area, in order to estimate the true cost-benefit ratio of antimicrobial textiles (53). Finally, although textiles impregnated with antimicrobials show promising results in terms of reducing microbial load and HAI rates, it is noted that this potential antimicrobial effect should not be overestimated under any circumstance, being indispensable to regulate periodic and standardized decontamination of these resources. Accordingly, innovative and practical methods that allow identifying microbial contamination in textiles (54) can be considered complementary tools for assessing the antimicrobial efficacy of impregnated textiles, also assisting in monitoring microbial resistance, while they can also act as markers of contamination by viable microorganisms on the surfaces of these textiles, even after extended periods of continuous exposure. In this way, effective recovery of microorganisms resistant to antimicrobials impregnated in textile materials is made possible and, consequently, surveillance of cross-resistance, co-resistance and resistance by co-regulation to other antimicrobials, especially pharmacological ones, a fundamental requirement for the safe implementation of impregnated/antimicrobial textiles in healthcare services. As for the limitations of the current study, it is noted that, given the extensive number of existing databases and Gray Literature materials, as well as the infinite possibilities of search strategies to be developed, considering the countless controlled terms and their respective synonyms, it is impossible to state that a full scan was carried out in the scientific literature on the theme of interest and, consequently, other potentially eligible studies may not have been identified. In addition to that, the marked heterogeneity of methodological configurations across the studies selected, as well as their methodological quality levels, made it impossible to conduct quantitative syntheses of the results evidenced, which precludes statistical inferences. Finally, as agreed in the review protocol, with the impossibility of performing a quantitative synthesis of the results, certainty of the evidence was not evaluated by means of the GRADE system, thus making it impossible to provide a basis for the elaboration of recommendations and guidelines to be implemented in the clinical practice. In relation to the contributions of this study, the systematic review design allowed identifying which substances with antimicrobial properties impregnated (either in isolation or together) in textiles, as well as which configurations of their use (by patients, by health professionals or in inanimate environments) in healthcare services, confer efficacy in reducing the microbial load present in these textiles and/or the HAI rates when compared to conventional textiles. In addition, the comprehensive search in the scientific literature made it possible to diagnose the current scenario on the theme of interest and, thus, to evidence the main gaps that still need to be bridged in order to provide safe and effective use of antimicrobial textiles in healthcare services.

In the current systematic review, the qualitative synthesis, taking into account the methodological quality of the studies selected, allowed identifying which antimicrobial substances impregnated in textiles used in healthcare services confer efficacy in reducing the microbial load present in these textiles and/or the HAI rates, when compared to conventional textiles. Among the antimicrobial substances impregnated in textiles and used by patients during the hospitalization period, it can be concluded that copper; silver; zinc oxide; titanium nanoparticles; and silver-doped titanium nanoparticles together; confer efficacy in reducing the microbial load present in these textiles and/or the HAI rates, when compared to conventional textiles. Among the antimicrobial substances impregnated in textiles used by health professionals during their respective work shifts, it can be concluded that quaternary ammonium; chlorhexidine; silver and copper together; quaternary ammonium, alcohols and isothiazolone derivatives together; and chitosan and dimethylol dimethyl hydantoin together; confer efficacy in reducing the microbial load present in these textiles, when compared to conventional textiles. Among the antimicrobial substances impregnated in textiles used in inanimate healthcare environments, it can be concluded that quaternary ammonium confers efficacy in reducing the microbial load present in these textiles when compared to conventional textiles. Due to the scarcity of research studies regarding adverse events presented by the patients and health professionals after using or entering into contact with textiles impregnated with antimicrobial substances, there were difficulties meeting the objective of listing them in the current review. However, in the studies that conducted such analyses, it can be verified that the individuals who used these textiles were not exempt from presenting signs and symptoms of cutaneous toxicity. When used by patients, copper-impregnated textiles did not induce adverse events, whereas textiles impregnated with zinc oxide induced itching, erythema and/or rash. When used by health professionals, textiles impregnated with chlorhexidine and with chitosan and dimethylol dimethyl hydantoin together did not induce adverse events, whereas textiles impregnated with silver and quaternary ammonium induced pruritus, erythema and/or rash.

Conceptualization, study design, data acquisition, data analysis, interpretation of results, and drafted the manuscript: GS, LV, HC, AS, EW, DA, and RS. Revised manuscript: GS, LV, AS, and DA. All authors approved the final version and agree to be accountable for all aspects of this work.