Chlorhexidine and octenidine use, carriage of qac genes, and reduced antiseptic susceptibility in methicillin-resistant Staphylococcus aureus isolates from a healthcare network

Octenidine exposure was not associated with reduced octenidine susceptibility of meticillin-resistant Staphylococcus aureus in an extended-care facility in Singapore

OBJECTIVES

Antiseptics such as chlorhexidine gluconate (CHG) and octenidine dihydrochloride (OCT) are frequently used in hospitals to prevent and control the transmission of meticillin-resistant Staphylococcus aureus (MRSA). Given the increasing prevalence of reduced CHG susceptibility of MRSA, there are concerns about the possibility of reduced OCT susceptibility. This study evaluated the prevalence of reduced CHG and OCT susceptibility over 3 years, and assessed the association between OCT exposure and reduced OCT susceptibility in MRSA.

METHODS

MRSA isolates from inpatients who acquired MRSA in an extended-care facility between 2019 and 2021 were included in antiseptic susceptibility testing. Inpatients were exposed to universal daily CHG bathing from January to September 2019, and universal daily OCT bathing after October 2019. The minimum inhibitory concentrations (MICs) of CHG and OCT were determined using the broth microdilution method. Multi-variable logistic regression was used to assess if OCT exposure was independently associated with reduced OCT susceptibility.

RESULTS

Of 186 isolates, 179 (96%) had reduced CHG susceptibility (MIC ≥4 mg/L) and 46 (25%) had reduced OCT susceptibility (MIC ≥2 mg/L). Reduced OCT susceptibility rates were 26.9%, 13.8% and 14.3% in 2019, 2020 and 2021, respectively. Reduced CHG susceptibility rates were 95.4%, 100% and 95.9% in 2019, 2020 and 2021, respectively. OCT exposure was not associated with reduced OCT susceptibility (adjusted odds ratio 0.23, 95% confidence interval 0.08-0.75; P=0.014), after adjusting for age, gender, race, year of sample collection, days at risk in facility, hospitalization in preceding year, and MRSA colonization/infection in preceding year.

CONCLUSION

The prevalence of reduced OCT susceptibility has remained low, despite universal OCT bathing for extended inpatient care. However, the rate of reduced CHG susceptibility was high. OCT exposure was not associated with reduced OCT susceptibility in MRSA.

Contribution of the patient microbiome to surgical site infection and antibiotic prophylaxis failure in spine surgery

Despite modern antiseptic techniques, surgical site infection (SSI) remains a leading complication of surgery. However, the origins of SSI and the high rates of antimicrobial resistance observed in these infections are poorly understood. Using instrumented spine surgery as a model of clean (class I) skin incision, we prospectively sampled preoperative microbiomes and postoperative SSI isolates in a cohort of 204 patients. Combining multiple forms of genomic analysis, we correlated the identity, anatomic distribution, and antimicrobial resistance profiles of SSI pathogens with those of preoperative strains obtained from the patient skin microbiome. We found that 86% of SSIs, comprising a broad range of bacterial species, originated endogenously from preoperative strains, with no evidence of common source infection among a superset of 1610 patients. Most SSI isolates (59%) were resistant to the prophylactic antibiotic administered during surgery, and their resistance phenotypes correlated with the patient's preoperative resistome (P = 0.0002). These findings indicate the need for SSI prevention strategies tailored to the preoperative microbiome and resistome present in individual patients.

Emergence and clonal expansion of a qacA-harbouring sequence type 45 lineage of methicillin-resistant Staphylococcus aureus

The past decade has seen an increase in the prevalence of sequence type (ST) 45 methicillin-resistant Staphylococcus aureus (MRSA), yet the underlying drivers for its emergence and spread remain unclear. To better understand the worldwide dissemination of ST45 S. aureus, we performed phylogenetic analyses of Australian isolates, supplemented with a global population of ST45 S. aureus genomes. Our analyses revealed a distinct lineage of multidrug-resistant ST45 MRSA harbouring qacA, predominantly found in Australia and Singapore. Bayesian inference predicted that the acquisition of qacA occurred in the late 1990s. qacA was integrated into a structurally variable region of the chromosome containing Tn552 (carrying blaZ) and Tn4001 (carrying aac(6')-aph(2")) transposable elements. Using mutagenesis and in vitro assays, we provide phenotypic evidence that qacA confers tolerance to chlorhexidine. These findings collectively suggest both antimicrobial resistance and the carriage of qacA may play a role in the successful establishment of ST45 MRSA.

Impact of daily octenidine skin washing versus nonwashing on antiseptic tolerance of coagulase-negative staphylococci in two neonatal intensive care units with different skin cleansing practices

Background

There is wide variation in practices regarding routine bathing/washing of babies in neonatal intensive care units (NICUs). Evidence is lacking as to the benefit of routine antiseptic washes for reducing infection. We aimed to compare the antiseptic tolerance of Coagulase Negative Staphylococci (CoNS) within two UK NICUs with very different approaches to skin washing.

Methods

We compared antiseptic susceptibility of CoNS isolated from skin swabs of neonates admitted to the Norfolk and Norwich University Hospital (NNUH) NICU in December 2017-March 2018 with those isolated in the Bradford Royal Infirmary (BRI) NICU in January-March 2020. The NNUH does not practise routine whole-body washing whereas BRI practises daily whole-body washing from post-menstrual age 27 weeks using Octenisan wash lotion (0.3% octenidine; 1 minute contact time before washing off with sterile water). A total of 78 CoNS isolates from BRI and 863 from the NNUH were tested for susceptibility against the antiseptics octenidine (OCT) and chlorhexidine (CHX).

Results

Isolates from the BRI with practice of routine washing did not show increased antiseptic tolerance to OCT or CHX. Isolates from the NNUH which does not practise routine whole-body washing and rarely uses octenidine, were comparatively less susceptible to both CHX and OCT antiseptics.

Conclusions

Daily whole-body skin washing with OCT does not appear to select for CoNS isolates that are antiseptic tolerant towards OCT and CHX. There remains considerable uncertainty about the impact of different antiseptic regimes on neonatal skin microbiota, the benefit of routine washing, and the development of antiseptic tolerance in the NICU.

Characterisation of neonatal Staphylococcus capitis NRCS-A isolates compared with non NRCS-A Staphylococcus capitis from neonates and adults

Staphylococcus capitis is a frequent cause of late-onset sepsis in neonates admitted to Neonatal Intensive Care Units (NICU). One clone of S. capitis, NRCS-A has been isolated from NICUs globally although the reasons for the global success of this clone are not well understood.We analysed a collection of S. capitis colonising babies admitted to two NICUs, one in the UK and one in Germany as well as corresponding pathological clinical isolates. Genome analysis identified a population structure of three groups; non-NRCS-A isolates, NRCS-A isolates, and a group of 'proto NRCS-A' - isolates closely related to NRCS-A but not associated with neonatal infection. All bloodstream isolates belonged to the NRCS-A group and were indistinguishable from strains carried on the skin or in the gut. NRCS-A isolates showed increased tolerance to chlorhexidine and antibiotics relative to the other S. capitis as well as enhanced ability to grow at higher pH values. Analysis of the pangenome of 138 isolates identified characteristic nsr and tarJ genes in both the NRCS-A and proto groups. A CRISPR-cas system was only seen in NRCS-A isolates which also showed enrichment of genes for metal acquisition and transport.We found evidence for transmission of S. capitis NRCS-A within NICU, with related isolates shared between babies and multiple acquisitions by some babies. Our data show NRCS-A strains commonly colonise uninfected babies in NICU representing a potential reservoir for potential infection. This work provides more evidence that adaptation to survive in the gut and on skin facilitates spread of NRCS-A, and that metal acquisition and tolerance may be important to the biology of NRCS-A. Understanding how NRCS-A survives in NICUs can help develop infection control procedures against this clone.

Biocides in the Hospital Environment: Application and Tolerance Development

Hospital-acquired infections are a rising problem with consequences for patients, hospitals, and health care workers. Biocides can be employed to prevent these infections, contributing to eliminate or reduce microorganisms' concentrations at the hospital environment. These antimicrobials belong to several groups, each with distinct characteristics that need to be taken into account in their selection for specific applications. Moreover, their activity is influenced by many factors, such as compound concentration and the presence of organic matter. This article aims to review some of the chemical biocides available for hospital infection control, as well as the main factors that influence their efficacy and promote susceptibility decreases, with the purpose to contribute for reducing misusage and consequently for preventing the development of resistance to these antimicrobials.

The potential of microalgal sources as coating materials: A case study for the development of biocompatible surgical sutures

Sutures are considered as surgical materials that form excellent surfaces to integrate the postoperative parts of the body. These materials present suitable platforms for potential bacterial penetrations. Therefore, coating these biomedical materials with biocompatible compounds is seen as a potential approach to improve their properties while avoiding adverse effects. The aim of this study was to evaluate Arthrospira platensis, Haematacoccus pluvialis, Chlorella minutissima, Botyrococcus braunii, and Nostoc muscorum as potential surgical suture coating materials. Their crude extracts were absorbed into two different sutures as poly glycolic (90%)-co-lactic acid (10%) (PGLA) and poly dioxanone (PDO); then, their cytotoxic effects and antibacterial activities were examined. Both N. muscorum-coated sutures (PGLA and PDO) and A. platensis-coated (PGLA and PDO) sutures did not induce any toxic effect on L929 mouse fibroblast cells (>70% cell viability). The highest antibacterial activity against Staphylococcus aureus was achieved with N. muscorum-coated PGLA and A. platensis-coated PGLA at 11.18 ± 0.54 mm and 9.52 ± 1.15 mm, respectively. These sutures were examined by mechanical analysis, and found suitable according to ISO 10993-5. In comparison with the commercial antibacterial agent (chlorohexidine), the results proved that N. muscorum extract can be considered as the most promising suture coating material for the human applications.

Central-line associated bloodstream infections in intensive care units before and after implementation of daily antiseptic bathing with chlorhexidine or octenidine: a post-hoc analysis of a cluster-randomised controlled trial

BACKGROUNDS

Antiseptic bathing did not reduce central-line (CL) associated bloodstream infection (CLABSI) rates in intensive care units (ICU) according to a recent cluster randomised controlled trial (cRCT). However, this analysis did not consider baseline infection rates. Our post-hoc analysis of this cRCT aimed to use a before-after comparison to examine the effect of daily bathing with chlorhexidine, octenidine or water and soap (control) on ICU-attributable CLABSI rates.

METHODS

A post-hoc analysis of a multi-center cRCT was done. ICUs that did not yet perform routine antiseptic bathing were randomly assigned to one of three study groups applying daily bathing with 2% chlorhexidine-impregnated cloths, 0.08% octenidine wash mitts or water and soap (control) for 12 months. Baseline data was assessed 12 months before the intervention started when all ICUs routinely used water and soap. Poisson regression and generalised estimating equation models were applied to identify changes of CLABSI rates per 1000 CL days between intervention and baseline periods in each study group.

RESULTS

The cRCT was conducted in 72 ICUs (24 per study group) including 76,139 patients in the baseline and 76,815 patients in the intervention period. In the chlorhexidine group, incidence density of CLABSI was reduced from 1.48 to 0.90 CLABSI per 1000 CL days comparing baseline versus intervention period (P = 0.0085). No reduction was observed in the octenidine group (1.26 versus 1.47 CLABSI per 1000 CL days, P = 0.8735) and the control group (1.20 versus 1.17, P = 0.3298). Adjusted incidence rate ratios (intervention versus baseline) were 0.63 (95%CI 0.46-0.87, P = 0.0172) in the chlorhexidine, 1.17 (95% CI 0.79-1.72, P = 0.5111) in the octenidine and 0.98 (95% CI 0.60-1.58, P = 0.9190) in the control group. Chlorhexidine bathing reduced CLABSI with gram-positive bacteria, mainly coagulase-negative staphylococci (CoNS).

CONCLUSIONS

In this post-hoc analysis of a cRCT, the application of 2% chlorhexidine-impregnated cloths reduced ICU-attributable CLABSI. This preventive effect of chlorhexidine was restricted to CLABSI caused by gram-positive pathogens (CoNS). In contrast, 0.08% octenidine wash mitts did not reduce CLABSI rates in ICUs. Trial registration Registration number DRKS00010475, registration date August 18, 2016.

Identifying and elucidating the resistance of Staphylococcus aureus isolated from hospital environment to conventional disinfectants

BACKGROUND

Staphylococcus aureus is a nosocomial pathogen, detection and elucidation of its resistance mechanisms to conventional disinfectants may aid in limiting its spread on environmental surfaces in health care settings. In the current study, disinfectant susceptibility of S. aureus strains isolated from the hospital environment as well as possible associations between the presence of disinfectant-resistance genes and reduced susceptibility to disinfectants was investigated.

METHODS

A total of 245 samples were collected from the hospital environmental surfaces. The minimum inhibitory (MIC) and bactericidal concentrations (MBC) of disinfectants against S. aureus isolates were determined using the micro-broth dilution method. The qac genes (qacA, qacE, and qacΔE1) were detected by PCR and confirmed by sanger sequencing.

RESULTS

A total of 47 S. aureus strains were isolated, with more than 85% of them showing methicillin resistance. The qacA, qacE, and qac∆E1 genes were found in 23.4%, 29.7%, and 4.2% isolates respectively. All the isolates with qac genes had higher MIC and MBC values to selected disinfectants.

CONCLUSIONS

Significant methicillin resistant S. aureus (MRSA) contamination in the hospital environment was detected. Furthermore, higher qac gene frequencies were found in MRSA isolates that also correlated with higher MIC/MBC values to different disinfectants. The study proposes that hospitals should develop policies to determine disinfectant MICs against the common environmental isolates to contain the spread of resistant strains.

Synergistic effects of length of stay and prior MDRO carriage on the colonization and co-colonization of methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and carbapenemase-producing Enterobacterales across healthcare settings

OBJECTIVE

To characterize the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and carbapenemase-producing Enterobacterales (CPE) co-colonization and to compare risk factors between healthcare facility types.

DESIGN, SETTING, AND PARTICIPANTS

We conducted a 3-year cross-sectional study among patients admitted to an acute-care hospital (ACH) and its 6 closely affiliated intermediate- and long-term care facilities (ILTCFs) in Singapore in June and July of 2014-2016.

METHODS

Specimens were concurrently collected from nares, axillae, and groins for MRSA detection, and from rectum or stool for VRE and CPE detection. Co-colonization was defined as having >1 positive culture of MRSA/VRE/CPE. Multinomial logistic regression was performed to determine predictors of co-colonization.

RESULTS

Of 5,456 patients recruited, 176 (3.2%) were co-colonized, with higher prevalence among patients in ITCFs (53 of 1,255, 4.2%) and the ACH (120 of 3,044, 3.9%) than LTCFs (3 of 1,157, 0.3%). MRSA/VRE was the most common type of co-colonization (162 of 5,456, 3.0%). Independent risk factors for co-colonization included male sex (odds ratio [OR], 1.96; 95% confidence interval [CI], 1.37-2.80), prior antibiotic therapy of 1-3 days (OR, 10.39; 95% CI, 2.08-51.96), 4-7 days (OR, 4.89; 95% CI, 1.01-23.68), >7 days (OR, 11.72; 95% CI, 2.81-48.85), and having an open wound (OR, 2.34; 95% CI, 1.66-3.29). Additionally, we detected the synergistic interaction of length of stay >14 days and prior multidrug-resistant organism (MDRO) carriage on co-colonization. Having an emergency surgery was a significant predictor of co-colonization in ACH patients, and we detected a dose-response association between duration of antibiotic therapy and co-colonization in ILTCF patients.

CONCLUSIONS

We observed common and differential risk factors for MDRO co-colonization across healthcare settings. This study has identified at-risk groups that merit intensive interventions, particularly patients with prior MDRO carriage and longer length of stay.

Role of antiseptics in the prevention and treatment of infections in nursing homes

Inadequate infection control, wound care, and oral hygiene protocols in nursing homes pose challenges to residents' quality of life. Based on the outcomes from a focus group meeting and a literature search, this narrative review evaluates the current and potential roles of antiseptics within nursing home infection management procedures. We examine contemporary strategies and concerns within the management of meticillin-resistant Staphylococcus aureus (MRSA; including decolonization regimes), chronic wound care, and oral hygiene, and review the available data for the use of antiseptics, with a focus on povidone-iodine. Compared with chlorhexidine, polyhexanide, and silver, povidone-iodine has a broader spectrum of antimicrobial activity, with rapid and potent activity against MRSA and other microbes found in chronic wounds, including biofilms. As no reports of bacterial resistance or cross-resistance following exposure to povidone-iodine exist, it may be preferable for MRSA decolonization compared with mupirocin and chlorhexidine, which can lead to resistant MRSA strains. Povidone-iodine oral products have greater efficacy against oral pathogens compared with other antiseptics such as chlorhexidine mouthwash, highlighting the clinical benefit of povidone-iodine in oral care. Additionally, povidone-iodine-based products, including mouthwash, have demonstrated rapid in-vitro virucidal activity against SARS-CoV-2 and may help reduce its transmission if incorporated into nursing home coronavirus 2019 control protocols. Importantly, povidone-iodine activity is not adversely affected by organic material, such as that found in chronic wounds and the oral cavity. Povidone-iodine is a promising antiseptic agent for the management of infections in the nursing home setting, including MRSA decolonization procedures, chronic wound management, and oral care.

Towards a Harmonized Terminology: A Glossary for Biocide Susceptibility Testing

Disinfection is a key strategy to reduce the burden of infections. The contact of bacteria to biocides-the active substances of disinfectants-has been linked to bacterial adaptation and the development of antimicrobial resistance. Currently, there is no scientific consensus on whether the excessive use of biocides contributes to the emergence and spread of multidrug resistant bacteria. The comprehensive analysis of available data remains a challenge because neither uniform test procedures nor standardized interpretive criteria nor harmonized terms are available to describe altered bacterial susceptibility to biocides. In our review, we investigated the variety of criteria and the diversity of terms applied to interpret findings in original studies performing biocide susceptibility testing (BST) of field isolates. An additional analysis of reviews summarizing the knowledge of individual studies on altered biocide susceptibility provided insights into currently available broader concepts for data interpretation. Both approaches pointed out the urgent need for standardization. We, therefore, propose that the well-established and approved concepts for interpretation of antimicrobial susceptibility testing data should serve as a role model to evaluate biocide resistance mechanisms on a single cell level. Furthermore, we emphasize the adaptations necessary to acknowledge the specific needs for the evaluation of BST data. Our approach might help to increase scientific awareness and acceptance.

Phenotypic and Molecular Detection of Antiseptic Resistance Genes among Clinical Staphylococcus aureus Isolates During COVID-19 Pandemic

The coronavirus disease (COVID-19) pandemic has expanded the use of chlorhexidine digluconate, a biocide frequently used in hospitals, to inhibit the spread of infection. Genes responsible for resistance against the quaternary ammonium compound qac in Staphylococcus aureus isolates have been shown to confer tolerance to a number of biocidal chemicals, including chlorhexidine. The aim of this study was to determine the occurrence of antiseptic resistance genes (qacA/B and qacC) in clinical isolates of methicillin-susceptible (MSSA) and methicillin-resistant Staphylococcus aureus (MRSA). The study also aimed to investigate the association between the presence of the mecA, qacA/B, and qacC genes in MRSA isolates and the susceptibility of the isolates to chlorhexidine to evaluate its future use in the Theodor Bilharz Research Institute (TBRI) hospital, following the Centers for Disease Control and Prevention recommendations for patients with MRSA. S. aureus isolates (n = 100) were collected from inpatients and outpatients at TBRI. A minimal inhibitory concentration of chlorhexidine was also detected. Polymerase chain reaction was used to detect the mecA, qacA/B, and qacC genes. The results revealed that 84% of S. aureus isolates were MRSA. MRSA (61.9%) and MSSA (68.8%) isolates were susceptible to chlorhexidine. The qacA/B gene was more dominant, being detected in 34%, while qacC was detected in only 5% of S. aureus isolates. All S. aureus isolates with reduced susceptibility to chlorhexidine harbored either the qacA/B or qacC genes. The clinical use of chlorhexidine may continue to increase, emphasizing the significance of continuous caution underlining the emergence of new clones with reduced susceptibility and avoiding antiseptic misuse.

Octenidine's Efficacy: A Matter of Interpretation or the Influence of Experimental Setups?

With its broad antimicrobial spectrum and non-specific mode of action via membrane disruption, any resistance to octenidine (OCT) seems unlikely and has not been observed in clinical settings so far. In this study, we aimed to investigate the efficacy of OCT against Escherichia coli and mutants lacking specific lipid head groups which, due to altered membrane properties, might be the root cause for resistance development of membrane-active compounds. Furthermore, we aimed to test its efficacy under different experimental conditions including different solvents for OCT, bacterial concentration and methods for analysis. Our primary goal was to estimate how many OCT molecules are needed to kill one bacterium. We performed susceptibility assays by observing bacterial growth behavior, using a Bioscreen in an analogous manner for every condition. The growth curves were recorded for 20 h at 420-580 nm in presence of different OCT concentrations and were used to assess the inhibitory concentrations (IC_100%) for OCT. Bacterial concentrations given in cell numbers were determined, followed by Bioscreen measurement by manual colony counting on agar plates and QUANTOM^TM cell staining. This indicated a significant variance between both methods, which influenced IC_100% of OCT, especially when used at low doses. The binding capacity of OCT to E. coli was investigated by measuring UV-absorbance of OCT exposed to bacteria and a common thermodynamic framework based on Bioscreen measurements. Results showed that OCT's antimicrobial activity in E. coli is not affected by changes at the membrane level but strongly dependent on experimental settings in respect to solvents and applied bacterial counts. More OCT was required when the active was dissolved in phosphate or Hepes buffers instead of water and when higher bacterial concentration was used. Furthermore, binding studies revealed that 10⁷-10⁸ OCT molecules bind to bacteria, which is necessary for the saturation of the bacterial surface to initiate the killing cascade. Our results clearly demonstrate that in vitro data, depending on the applied materials and the methods for determination of IC_100%, can easily be misinterpreted as reduced bacterial susceptibility towards OCT.

In vitro evaluation of the antimicrobial activity of antiseptics against clinical Acinetobacter baumannii strains isolated from combat wounds

Healthcare-associated infections (HCAIs) are among the most prominent medical problems worldwide. In the context of increasing antibiotic resistance globally, the use of antiseptics as the main active agent and potentiator of antibiotics for the treatment of purulent-inflammatory complications of traumatic wounds, burns, and surgical wounds can be considered to tackle opportunistic infections and their prevention during war. This study presents a comparative investigation of the antimicrobial efficacy of antiseptics used for surgical antisepsis and antiseptic treatment of skin, mucous membranes, and wounds against multidrug-resistant clinical isolates of Acinetobacter baumannii as a wound pathogen of critical priority (according to the WHO). It was found that strains of A. baumannii, which have natural and acquired resistance to antimicrobial drugs, remain susceptible to modern antiseptics. Antiseptic drugs based on decamethoxine, chlorhexidine, octenidine, polyhexanide, and povidone-iodine 10% and 2% provide effective bactericidal activity against A. baumannii within the working concentrations of these drugs. Chlorhexidine and decamethoxine can inhibit biofilm formation by A. baumannii cells. In terms of bactericidal properties and biofilm formation inhibition, chlorhexidine and decamethoxine are the most effective of all tested antiseptics.

Effect of antiseptic bathing with chlorhexidine or octenidine on central-line associated bloodstream infections in intensive care patients: a cluster-randomised controlled trial

OBJECTIVES

Our study aimed to compare the effect of daily bathing with chlorhexidine, octenidine or water and soap (routine care = control) on central-line (CL) associated bloodstream infection (CLABSI) rates in intensive care units (ICUs).

METHODS

A multi-center cluster-randomised controlled trial was done with a 12-months intervention period from February 1, 2017, to January 31, 2018 (octenidine and routine care group) or from June 1, 2017 to May 31, 2018 (chlorhexidine group). Wards were randomly assigned to one of two decolonisation regimes or routine care (control). Intervention included daily bathing with 2% chlorhexidine-impregnated cloths or 0.08% octenidine wash mitts for 12 months, while the control group used water and soap (routine care). The primary outcome was incidence density of CLABSI per 1,000 CL days. Poisson regression and generalised estimating equation models (GEE) were applied.

RESULTS

A total of 72 ICUs with 76,815 patients (22,897 patients in the chlorhexidine group, 25,127 in the octenidine group and 28,791 in the routine care group) were included. Incidence densities were 0.9 CLABSI per 1,000 CL days (95%CI 0.67 - 1.19) in the chlorhexidine group, 1.47 (95%CI 1.17 - 1.81) in the octenidine group and 1.17 (95%CI 0.93 - 1.45) in the routine care group. Adjusted incidence rate ratios of CLABSI were 0.69 (95%CI 0.37-1.22, p=0.25) in the chlorhexidine and 1.22 (95%CI 0.54-2.75, p=0.63) in the octenidine group (compared with routine care).

CONCLUSION

Antiseptic bathing with 2% chlorhexidine-impregnated cloths and 0.08% octenidine wash mitts lack a significant preventive effect on CLABSI rates in ICUs. However, our trial has a high likelihood of being underpowered as CLABSI rates in the routine care group were approximately 40% lower than initially assumed. This trial is registered with the German register for clinical trials (18/08/2016, number DRKS00010475).

Efflux Pump Mediated Antimicrobial Resistance by Staphylococci in Health-Related Environments: Challenges and the Quest for Inhibition

The increasing emergence of antimicrobial resistance in staphylococcal bacteria is a major health threat worldwide due to significant morbidity and mortality resulting from their associated hospital- or community-acquired infections. Dramatic decrease in the discovery of new antibiotics from the pharmaceutical industry coupled with increased use of sanitisers and disinfectants due to the ongoing COVID-19 pandemic can further aggravate the problem of antimicrobial resistance. Staphylococci utilise multiple mechanisms to circumvent the effects of antimicrobials. One of these resistance mechanisms is the export of antimicrobial agents through the activity of membrane-embedded multidrug efflux pump proteins. The use of efflux pump inhibitors in combination with currently approved antimicrobials is a promising strategy to potentiate their clinical efficacy against resistant strains of staphylococci, and simultaneously reduce the selection of resistant mutants. This review presents an overview of the current knowledge of staphylococcal efflux pumps, discusses their clinical impact, and summarises compounds found in the last decade from plant and synthetic origin that have the potential to be used as adjuvants to antibiotic therapy against multidrug resistant staphylococci. Critically, future high-resolution structures of staphylococcal efflux pumps could aid in design and development of safer, more target-specific and highly potent efflux pump inhibitors to progress into clinical use.

The High Impact of Staphylococcus aureus Biofilm Culture Medium on In Vitro Outcomes of Antimicrobial Activity of Wound Antiseptics and Antibiotic

The staphylococcal biofilm-based infections of wounds still pose a significant therapeutical challenge. Treated improperly, they increase the risk of limb amputation or even death of the patient. The present algorithms of infected wound treatment include, among others, the application of antiseptic substances. In vitro wound biofilm models are applied in order to scrutinize their activity. In the present work, using a spectrum of techniques, we showed how the change of a single variable (medium composition) in the standard in vitro model translates not only to shift in staphylococcal biofilm features but also to the change of efficacy of clinically applied wound antimicrobials such as octenidine, polyhexamethylene biguanide, chlorhexidine, hypochlorite solutions, and locally applied gentamycin. The data presented in this study may be of a pivotal nature, taking into consideration the fact that results of in vitro analyses are frequently used to propagate application of specific antimicrobials in hospitals and ambulatory care units.

The alarming association between antibiotic resistance and reduced susceptibility to biocides in nosocomial MRSA isolates from two regional hospitals in Egypt

Methicillin-resistant Staphylococcus aureus is one of the major clinical problems in hospitals because of its resistance to many antimicrobials. Biocides are used in hospitals to control nosocomial infections. This work aimed to investigate the relationship between the presence of integrons and reduced susceptibility to both biocides and antimicrobials in nosocomial multidrug-resistant (MDR)-MRSA isolates. A total of 114 clinical and eight environmental MRSA isolates were collected from Zagazig University Hospitals and El-Ahrar Educational Hospital, Egypt. These isolates were identified as MRSA by disk diffusion method (DDM) and confirmed by PCR. Susceptibility profile against 12 antibiotics and five biocides was determined by DDM and agar dilution method, respectively. Presence of integrons was investigated by PCR in MDR isolates. Seventy-five clinical and six environmental isolates were MDR and had reduced susceptibility to biocides. Class I integron was detected in plasmid DNA of 34 isolates and genomic DNA of 14 isolates. Meanwhile, class II integron was only detected in plasmid DNA of 10 clinical isolates. This study revealed a high prevalence of MDR-MRSA clinical and environmental isolates, both had reduced susceptibility to investigated biocides. Class I integron was more predominant in plasmid DNA of isolates, indicating that plasmid is a major carrier for integrons that transfer resistance genes. In conclusion, the association between antibiotic resistance and biocides reduced susceptibility is alarming. The selection of curative antibiotic should depend on the antimicrobial susceptibility profile. Furthermore, biocides should always be used at appropriate concentrations to prevent the evolution of resistance and to control the hospital-transmission of MRSA.

In Vitro Efficacy of Bacterial Cellulose Dressings Chemisorbed with Antiseptics against Biofilm Formed by Pathogens Isolated from Chronic Wounds

Local administration of antiseptics is required to prevent and fight against biofilm-based infections of chronic wounds. One of the methods used for delivering antiseptics to infected wounds is the application of dressings chemisorbed with antimicrobials. Dressings made of bacterial cellulose (BC) display several features, making them suitable for such a purpose. This work aimed to compare the activity of commonly used antiseptic molecules: octenidine, polyhexanide, povidone-iodine, chlorhexidine, ethacridine lactate, and hypochlorous solutions and to evaluate their usefulness as active substances of BC dressings against 48 bacterial strains (8 species) and 6 yeast strains (1 species). A silver dressing was applied as a control material of proven antimicrobial activity. The methodology applied included the assessment of minimal inhibitory concentrations (MIC) and minimal biofilm eradication concentration (MBEC), the modified disc-diffusion method, and the modified antibiofilm dressing activity measurement (A.D.A.M.) method. While in 96-well plate-based methods (MIC and MBEC assessment), the highest antimicrobial activity was recorded for chlorhexidine, in the modified disc-diffusion method and in the modified A.D.A.M test, povidone-iodine performed the best. In an in vitro setting simulating chronic wound conditions, BC dressings chemisorbed with polyhexanide, octenidine, or povidone-iodine displayed a similar or even higher antibiofilm activity than the control dressing containing silver molecules. If translated into clinical conditions, the obtained results suggest high applicability of BC dressings chemisorbed with antiseptics to eradicate biofilm from chronic wounds.

Reductions in Methicillin-resistant Staphylococcus aureus, Clostridium difficile Infection and Intensive Care Unit-Acquired Bloodstream Infection Across the United Kingdom Following Implementation of a National Infection Control Campaign

Background

Methicillin-resistant Staphylococcus aureus (MRSA) and Clostridium difficile infections declined across the UK National Health Service in the decade that followed implementation of an infection control campaign. The national impact on intensive care unit (ICU)-acquired infections has not been documented.

Methods

Data on MRSA, C. difficile, vancomycin-resistant Enterococcus (VRE), and ICU–acquired bloodstream infections (UABSIs) for 1 189 142 patients from 2007 to 2016 were analyzed. Initial coverage was 139 ICUs increasing to 276 ICUs, representing 100% of general adult UK ICUs.

Results

ICU MRSA and C. difficile acquisitions per 1000 patients decreased between 2007 and 2016 (MRSA acquisitions, 25.4 to 4.1; and C. difficile acquisitions, 11.1 to 3.5), whereas VRE acquisitions increased from 1.5 to 5.9. There were 13 114 UABSIs in 1.8% of patients who stayed longer than 48 hours on ICU. UABSIs fell from 7.3 (95% confidence interval [CI], 6.9–7.6) to 1.6 (95% CI, 1.5–1.7)/1000 bed days. Adjusting for patient factors, the incidence rate ratio was 0.21 (95% CI, 0.19–0.23, P < .001) from 2007 to 2016. The greatest reduction, comparing rates in 2007/08 and 2015/16, was for MRSA (97%), followed by P. aeruginosa (81%), S. aureus (79%) and Candida spp (72%), with lower reductions for the coliforms (E. coli 57% and Klebsiella 49%).

Conclusions

Large decreases in ICU-acquired infections occurred across the UK ICU network linked with the first few years of a national infection control campaign, but rates have since been static. Further reductions will likely require a new intervention framework.

Povidone Iodine: Properties, Mechanisms of Action, and Role in Infection Control and Staphylococcus aureus Decolonization

Nasal decolonization is an integral part of the strategies used to control and prevent the spread of methicillin-resistant Staphylococcus aureus (MRSA) infections. The two most commonly used agents for decolonization are intranasal mupirocin 2% ointment and chlorhexidine wash, but the increasing emergence of resistance and treatment failure has underscored the need for alternative therapies. This article discusses povidone iodine (PVP-I) as an alternative decolonization agent and is based on literature reviewed during an expert’s workshop on resistance and MRSA decolonization.

Nasal decolonization is an integral part of the strategies used to control and prevent the spread of methicillin-resistant Staphylococcus aureus (MRSA) infections. The two most commonly used agents for decolonization are intranasal mupirocin 2% ointment and chlorhexidine wash, but the increasing emergence of resistance and treatment failure has underscored the need for alternative therapies. This article discusses povidone iodine (PVP-I) as an alternative decolonization agent and is based on literature reviewed during an expert’s workshop on resistance and MRSA decolonization. Compared to chlorhexidine and mupirocin, respectively, PVP-I 10 and 7.5% solutions demonstrated rapid and superior bactericidal activity against MRSA in in vitro and ex vivo studies. Notably, PVP-I 10 and 5% solutions were also active against both chlorhexidine-resistant and mupirocin-resistant strains, respectively. Unlike chlorhexidine and mupirocin, available reports have not observed a link between PVP-I and the induction of bacterial resistance or cross-resistance to antiseptics and antibiotics. These preclinical findings also translate into clinical decolonization, where intranasal PVP-I significantly improved the efficacy of chlorhexidine wash and was as effective as mupirocin in reducing surgical site infection in orthopedic surgery. Overall, these qualities of PVP-I make it a useful alternative decolonizing agent for the prevention of S. aureus infections, but additional experimental and clinical data are required to further evaluate the use of PVP-I in this setting.

Impact of formulary interventions on the minimum inhibitory concentration of methicillin-resistant Staphylococcus aureus to mupirocin, chlorhexidine, and octenidine in a Singapore tertiary institution

Methicillin-resistant Staphylococcus aureus (MRSA) decolonization is an effective measure to prevent clinical infection but resistance is a concern. We aim to evaluate the impact of mupirocin (MUP) ointment formulary removal, plateauing use of chlorhexidine gluconate (CHG), and hospital-wide introduction of octenidine (OCT)-based products on the minimum inhibitory concentration (MIC) of MRSA to MUP, CHG, and OCT in our hospital. A prevalence study was conducted at three time points (TP) on consecutive MRSA screening isolates to evaluate for their MICs to MUP, CHG, and OCT using broth microdilution sensititre plates and detection of the ileS-2 gene encoding high-level MUP resistance in 2013 (pre-intervention TP1; n = 160), 2016 (early post-intervention TP2; n = 99) and 2017 (late post-intervention TP3; n = 76). Statistical analyses were performed using Chi square test with reference from TP1. There was a significant improvement in MUP susceptibility (MIC < 4 mcg/ml) from 71.9% (TP1) to 86.9% (TP2; p = 0.006) to 88.2% (TP3; p = 0.007). The prevalence of MUP high-level resistance (MIC > 256 mcg/ml) reduced from 25.0% (TP1) to 12.1% (TP2; p = 0.014) to 5.3% (TP3; p = 0.001). Likewise, the prevalence of isolates harboring the ileS-2 gene decreased from 28.1% (TP1) to 18.2% (TP2; p = 0.072) to 9.2% (TP3; p = 0.002). OCT MIC range remains stable at 0.5 to 1 mcg/ml across all three TPs. The proportion of isolates with reduced CHG susceptibility (MIC ≥ 4 mcg/ml) increased over the three TPs from 23.1 to 27.2% (p = 0.45) to 42.1% (p = 0.003). Active formulary regulations have an impact on the resistance profile of MRSA and can be used as a strategy to preserve the MRSA decolonization armamentarium.

Protecting patients from infection: Improving topical prophylaxis compliance on surgical wards

Background

At a medium-sized district general hospital in the heart of England, it was identified that compliance to the administration of topical prophylaxis on three general surgery wards had reduced to 23%, following implementation of an electronic medication prescription record. Therefore, a quality improvement project was commenced to improve this compliance to protect patients from meticillin-resistant Staphylococcus aureus (MRSA) colonisation and associated bacteraemia.

Aim

To improve compliance of topical prophylaxis administration on three surgical wards to protect patients from infection.

Method

Quality improvement plan - do - study - act (PDSA) cycles evaluated the effectiveness of four different strategies from baseline data which was 23% compliant in December 2016. These included teaching and communication strategies, prompts in medical notes, discontinuation of Mupirocin 2% nasal ointment as part of the topical prophylaxis regime and discontinuation of the topical wash lotion from requiring a prescription.

Results

The compliance of prophylaxis administration increased consistently throughout from 23% in December 2016 to 92% in March 2018. Consequently, the number of patients that developed a MRSA colonisation on the three wards reduced by 54%, from 13 in the 12 months before the study to six in the 12 months after the study.

Discussion

This study led to a change in the Trust MRSA Policy to better protect patients from infection, particularly surgical site infection and MRSA bacteraemia. It suggests that quality improvement methodology has a place in infection prevention practice.

2CS-CHXT Operon Signature of Chlorhexidine Tolerance among Enterococcus faecium Isolates

Chlorhexidine (CHX) is a broad-spectrum antiseptic widely used in community and clinical contexts for many years that has recently acquired higher relevance in nosocomial infection control worldwide. Despite this, CHX tolerance among Enterococcus faecium bacteria, representing one of the leading agents causing nosocomial infections, has been poorly understood. This study provides new phenotypic and molecular data for better identification of CHX-tolerant E. faecium subpopulations in community and clinical contexts. The chlorhexidine MIC (MIC_CHX) distribution of 106 E. faecium isolates suggested the occurrence of tolerant subpopulations in diverse sources (human, animal, food, environment) and phylogenomic backgrounds (clades A1/A2/B), with predominance in clade A1. They carried a specific variant of the 2CS-CHX^T operon, identified here. It encodes glucose and amino acid-polyamine-organocation family transporters, besides the DNA-binding response regulator ChtR, with a P102H mutation previously described only in CHX-tolerant clade A1 E. faecium, and the ChtS sensor. 2CS-CHX^T seems to be associated with three regulons modulating diverse bacterial biological functions. Combined data from normal MIC distribution and 2CS-CHX^T operon characterization support a tentative epidemiological cutoff (ECOFF) of 8 mg/liter to CHX, which is useful to detect tolerant E. faecium populations in future surveillance studies. The spread of tolerant E. faecium in diverse epidemiological backgrounds calls for the prudent use of CHX in multiple contexts.IMPORTANCE Chlorhexidine is one of the substances included in the World Health Organization's list of essential medicines, which comprises the safest and most effective medicines needed in global health systems. Although it has been widely applied as a disinfectant and antiseptic in health care (skin, hands, mouthwashes, eye drops) since the 1950s, its use in hospitals to prevent nosocomial infections has increased worldwide in recent years. Here, we provide a comprehensive study on chlorhexidine tolerance among strains of Enterococcus faecium, one of the leading nosocomial agents worldwide, and identify a novel 2CS-CHX^T operon as a signature of tolerant strains occurring in diverse phylogenomic groups. Our data allowed for the proposal of a tentative epidemiological cutoff of 8 mg/liter, which is useful to detect tolerant E. faecium populations in surveillance studies in community and clinical contexts. The prediction of 2CS-CHX^T regulons will also facilitate the design of future experimental studies to better uncover chlorhexidine tolerance among E. faecium bacteria.

Resistance and cross-resistance in Staphylococcus spp. strains following prolonged exposure to different antiseptics

OBJECTIVES

This aim of this study was to evaluate the potential of staphylococci to develop resistance and cross-resistance to antibiotics following exposure to antiseptics.

METHODS

The antibiotic susceptibility profile as well as the antiseptic minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBC) were determined for Staphylococcus epidermidis and Staphylococcus aureus clinical isolates and reference strains (methicillin resistant or not) before and after prolonged exposure to low concentrations of two antiseptics, namely chlorhexidine digluconate (CHG) and octenidine dihydrochloride (OCT).

RESULTS

Resistance was observed to both tested antiseptics following exposure. CHG exposure led to increased MICs in five of the six tested strains of S. epidermidis and S. aureus and also led to clinically decreased susceptibility to gentamicin in S. aureus ATCC 43300 (MRSA) and to penicillin and tetracycline in S. aureus ATCC 25923 (MSSA). OCT exposure led to an increased MIC only in S. epidermidis ATCC 12228 (MSSE) and also led to a clinically decreased susceptibility to penicillin in S. aureus clinical strain SAL. One strain (MSSE) showed a four-fold increase in the MIC against CHG. Several strains showed a two-fold increase in the MIC against CHG and only one strain (MSSE) against OCT.

CONCLUSION

These results support the urgent need to apply the same administration rules currently accepted for antibiotics to antiseptics in order to preserve the benefits both of antiseptics and antibiotics.