Hygienic hand disinfection: a comparative study with chlorhexidine detergents and soap

Systematic Analysis of Efflux Pump-Mediated Antiseptic Resistance in Staphylococcus aureus Suggests a Need for Greater Antiseptic Stewardship

S. aureus remains a significant cause of disease within hospitals and communities. To reduce the burden of S. aureus infections, antiseptics are ubiquitously used in our daily lives. Furthermore, many antiseptic compounds are dual purpose and are found in household products. The increased abundance of antiseptic compounds has selected for S. aureus strains that carry efflux pumps that increase resistance to antiseptic compounds; however, the effect of carrying multiple pumps within S. aureus is unclear. We demonstrated that an isogenic strain carrying multiple efflux pumps had an additive resistance phenotype to cetrimide. Moreover, in a strain carrying qacA and norA, increased chlorhexidine tolerance was observed after the strain was preexposed to subinhibitory concentrations of a different common-use antiseptic. Taken together, our findings demonstrate cooperation between antiseptic resistance efflux pumps and suggest that their protective phenotype may be exacerbated by priming with subinhibitory concentrations of household antiseptics.

Staphylococcus aureus-associated infections can be difficult to treat due to multidrug resistance. Thus, infection prevention is critical. Cationic antiseptics, such as chlorhexidine (CHX) and benzalkonium chloride (BKC), are liberally used in health care and community settings to prevent infection. However, increased administration of antiseptics has selected for S. aureus strains that show reduced susceptibilities to cationic antiseptics. This increased resistance has been associated with carriage of specific efflux pumps (QacA, QacC, and NorA). Since prior published studies focused on different strains and on strains carrying only a single efflux gene, the relative importance of these various systems to antiseptic resistance is difficult to ascertain. To overcome this, we engineered a collection of isogenic S. aureus strains that harbored norA, qacA, and qacC, individually or in combination. MIC assays showed that qacA was associated with increased resistance to CHX, cetrimide (CT), and BKC, qacC was associated with resistance to CT and BKC, and norA was necessary for basal-level resistance to the majority of tested antiseptics. When all three pumps were present in a single strain, an additive effect was observed in the MIC for CT. Transcriptional analysis revealed that expression of qacA and norA was significantly induced following exposure to BKC. Alarmingly, in a strain carrying qacA and norA, preexposure to BKC increased CHX tolerance. Overall, our results reveal increased antiseptic resistance in strains carrying multiple efflux pumps and indicate that preexposure to BKC, which is found in numerous daily-use products, can increase CHX tolerance.

IMPORTANCES. aureus remains a significant cause of disease within hospitals and communities. To reduce the burden of S. aureus infections, antiseptics are ubiquitously used in our daily lives. Furthermore, many antiseptic compounds are dual purpose and are found in household products. The increased abundance of antiseptic compounds has selected for S. aureus strains that carry efflux pumps that increase resistance to antiseptic compounds; however, the effect of carrying multiple pumps within S. aureus is unclear. We demonstrated that an isogenic strain carrying multiple efflux pumps had an additive resistance phenotype to cetrimide. Moreover, in a strain carrying qacA and norA, increased chlorhexidine tolerance was observed after the strain was preexposed to subinhibitory concentrations of a different common-use antiseptic. Taken together, our findings demonstrate cooperation between antiseptic resistance efflux pumps and suggest that their protective phenotype may be exacerbated by priming with subinhibitory concentrations of household antiseptics.

Quantifying the Effects of Water Temperature, Soap Volume, Lather Time, and Antimicrobial Soap as Variables in the Removal of Escherichia coli ATCC 11229 from Hands

The literature on hand washing, while extensive, often contains conflicting data, and key variables are only superficially studied or not studied at all. Some hand washing recommendations are made without scientific support, and agreement between recommendations is limited. The influence of key variables such as soap volume, lather time, water temperature, and product formulation on hand washing efficacy was investigated in the present study. Baseline conditions were 1 mL of a bland (nonantimicrobial) soap, a 5-s lather time, and 38°C (100°F) water temperature. A nonpathogenic strain of Escherichia coli (ATCC 11229) was the challenge microorganism. Twenty volunteers (10 men and 10 women) participated in the study, and each test condition had 20 replicates. An antimicrobial soap formulation (1% chloroxylenol) was not significantly more effective than the bland soap for removing E. coli under a variety of test conditions. Overall, the mean reduction was 1.94 log CFU (range, 1.83 to 2.10 log CFU) with the antimicrobial soap and 2.22 log CFU (range, 1.91 to 2.54 log CFU) with the bland soap. Overall, lather time significantly influenced efficacy in one scenario, in which a 0.5-log greater reduction was observed after 20 s with bland soap compared with the baseline wash (P = 0.020). Water temperature as high as 38°C (100°F) and as low as 15°C (60°F) did not have a significant effect on the reduction of bacteria during hand washing; however, the energy usage differed between these temperatures. No significant differences were observed in mean log reductions experienced by men and women (both 2.08 log CFU; P = 0.988). A large part of the variability in the data was associated with the behaviors of the volunteers. Understanding what behaviors and human factors most influence hand washing may help researchers find techniques to optimize the effectiveness of hand washing.

A meta-analysis of the published literature on the effectiveness of antimicrobial soaps

The goal of this research was to conduct a systematic quantitative analysis of the existing data in the literature in order to determine if there is a difference between antimicrobial and nonantimicrobial soaps and to identify the methodological factors that might affect this difference. Data on hand washing efficacy and experimental conditions (sample size, wash duration, soap quantity, challenge organism, inoculum size, and neutralization method) from published studies were compiled and transferred to a relational database. A total of 25 publications, containing 374 observations, met the study selection criteria. The majority of the studies included fewer than 15 observations with each treatment and included a direct comparison between nonantimicrobial soap and antimicrobial soap. Although differences in efficacy between antimicrobial and nonantimicrobial soap were small (∼0.5-log CFU reduction difference), antimicrobial soap produced consistently statistically significantly greater reductions. This difference was true for any of the antimicrobial compounds investigated where n was >20 (chlorhexidine gluconate, iodophor, triclosan, or povidone). Average log reductions were statistically significantly greater (∼2 log CFU) when either gram-positive or gram-negative transient organisms were deliberately added to hands compared with experiments done with resident hand flora (∼0.5 log CFU). Our findings support the importance of using a high initial inoculum on the hands, well above the detection limit. The inherent variability in hand washing seen in the published literature underscores the importance of using a sufficiently large sample size to detect differences when they occur.

Guidelines for the control of glycopeptide-resistant enterococci in hospitals

The increase since the mid 1980s in glycopeptide resistant enterococci (GRE) raised concerns about the limited options for antimicrobial therapy, the implications for ever-increasing numbers of immunocompromised hospitalised patients, and fuelled fears, now realised, for the transfer of glycopeptide resistance to more pathogenic bacteria, such as Staphylococcus aureus. These issues underlined the need for guidelines for the emergence and control of GRE in the hospital setting. This Hospital Infection Society (HIS) and Infection Control Nurses Association (ICNA) working party report reviews the literature relating to GRE prevention and control. It provides guidance on microbiological investigation, treatment and management, including antimicrobial prescribing and infection control measures. Evidence identified to support recommendations has been categorized. A risk assessment approach is recommended and areas for research and development identified.

Epidemiologic background of hand hygiene and evaluation of the most important agents for scrubs and rubs

The etiology of nosocomial infections, the frequency of contaminated hands with the different nosocomial pathogens, and the role of health care workers' hands during outbreaks suggest that a hand hygiene preparation should at least have activity against bacteria, yeasts, and coated viruses. The importance of efficacy in choosing the right hand hygiene product is reflected in the new Centers for Disease Control and Prevention guideline on hand hygiene (J. M. Boyce and D. Pittet, Morb. Mortal. Wkly. Rep. 51:1-45, 2002). The best antimicrobial efficacy can be achieved with ethanol (60 to 85%), isopropanol (60 to 80%), and n-propanol (60 to 80%). The activity is broad and immediate. Ethanol at high concentrations (e.g., 95%) is the most effective treatment against naked viruses, whereas n-propanol seems to be more effective against the resident bacterial flora. The combination of alcohols may have a synergistic effect. The antimicrobial efficacy of chlorhexidine (2 to 4%) and triclosan (1 to 2%) is both lower and slower. Additionally, both agents have a risk of bacterial resistance, which is higher for chlorhexidine than triclosan. Their activity is often supported by the mechanical removal of pathogens during hand washing. Taking the antimicrobial efficacy and the mechanical removal together, they are still less effective than the alcohols. Plain soap and water has the lowest efficacy of all. In the new Centers for Disease Control and Prevention guideline, promotion of alcohol-based hand rubs containing various emollients instead of irritating soaps and detergents is one strategy to reduce skin damage, dryness, and irritation. Irritant contact dermatitis is highest with preparations containing 4% chlorhexidine gluconate, less frequent with nonantimicrobial soaps and preparations containing lower concentrations of chlorhexidine gluconate, and lowest with well-formulated alcohol-based hand rubs containing emollients and other skin conditioners. Too few published data from comparative trials are available to reliably rank triclosan. Personnel should be reminded that it is neither necessary nor recommended to routinely wash hands after each application of an alcohol-based hand rub. Long-lasting improvement of compliance with hand hygiene protocols can be successful if an effective and accessible alcohol-based hand rub with a proven dermal tolerance and an excellent user acceptability is supplied, accompanied by education of health care workers and promotion of the use of the product.

Hand hygiene and aseptic technique in the emergency department

Hand hygiene and simple aseptic measures before invasive procedures are effective in reducing rates of healthcare-associated infection. The perceived urgency of a clinical situation in the emergency department, however, may influence medical staff's compliance with good practice in infection control. The aims of this prospective, single-blinded, observational study were twofold. First, to assess doctors' compliance with good practice in hand hygiene between patient episodes and asepsis during invasive procedures in the emergency department. Second, to assess the effect of clinical urgency on compliance with good practice in hand hygiene and asepsis during invasive procedures. Good practice standards for asepsis in invasive procedures and hand hygiene between patient episodes were compiled from a literature search. Doctors' compliance with these standards was observed in two emergency departments (UK and New Zealand). Observed clinical cases were classified as immediate, urgent and non-urgent based on the triage system. There was poor compliance with good practice guidelines for asepsis in invasive procedures in both centres. Staff achieved high compliance with the guidelines in only 27% of cases in the UK and 58% of cases in New Zealand. Clinical urgency did not appear to adversely affect compliance with aseptic good practice. Hand hygiene between patient consultations was very low at 14% in the UK and 12% in New Zealand. Asepsis and hand hygiene was poor in both the UK and New Zealand emergency departments. There may be a need for some compromise in standards of asepsis in very sick patients due to the urgency of the clinical situation. Compliance in all situations especially non-urgent procedures needs to be improved.

The effects of test variables on the efficacy of hand hygiene agents

BACKGROUND

Hand hygiene is essential to interrupting disease transmission in health care facilities. Multiple hand hygiene agents are currently available for use in the health care setting. To evaluate the utility of these agents, both the user acceptability and the efficacy need to be evaluated. Different hand hygiene test methodologies have been used to measure the efficacy of these agents, but efficacy results vary depending on variations to key parameters in these methodologies. The purpose of this study was to evaluate the effect of test variables on the efficacy of hand hygiene agents.

METHODS

Both a comprehensive literature review and original hand hygiene efficacy studies were undertaken. The literature review was conducted using a Medline search, and hand hygiene efficacy studies were conducted under the American Society for Testing and Materials (ASTM). E 1174 Standard Test Method for Evaluation of the Effectiveness of Health Care Personnel Handwash Formulation.

RESULTS

The literature review and our original data showed that the following variables affected the hand hygiene efficacy measurements: hand jewelry, experimental contamination versus normal flora, method of application of test organism, hand hygiene agent, concentration of active ingredient, volume of hand hygiene agent, duration of application of hand hygiene agent, method of application of hand hygiene agent, and study method (human challenge trial versus in vitro suspension test).

CONCLUSIONS

Although many methodological variables affect efficacy results, infection control professionals in their analysis of product information should always assess the results in light of the following key variables: concentration and type of active ingredient, duration of exposure to hand hygiene agent, volume of hand hygiene agent applied, test organism, and study method (ie, human challenge vs. in vitro suspension test).

A rapid and easy PCR-RFLP method for genotyping Serratia marcescens strains isolated in different hospital outbreaks and patient environments in the Lyon area, France

A new genotyping method for Serratia marcescens is described. This method uses the flagellin gene as target for polymerase chain reaction amplification and Alu I restriction fragment length polymorphism. The strains tested belonged to 13 different hospital clusters of S. marcescens isolated between 1983 and 1988, concerning outbreaks and/or patient environments in different hospital units in Lyon and the Rhone-Alpes region of France. Initially, the classification had been performed by marcescinotyping. These strains were then tested by ribotyping and genotyping of the flagellin gene. Genotyping showed similar classification to ribotyping. The genotyping method is the easiest technique, as reproducible as ribotyping, and with almost the same ability to discriminate different strains. It does not need expensive equipment, is more rapid, and is less labor intensive than ribotyping. With this method, all strains of S. marcescens including sporadic isolates could be amplified and typed. Antibiotic sensitivity determination was found to be a useful complementary and confirmation test for all these typing methods.

Vancomycin-resistant enterococci

After they were first identified in the mid-1980s, vancomycin-resistant enterococci (VRE) spread rapidly and became a major problem in many institutions both in Europe and the United States. Since VRE have intrinsic resistance to most of the commonly used antibiotics and the ability to acquire resistance to most of the current available antibiotics, either by mutation or by receipt of foreign genetic material, they have a selective advantage over other microorganisms in the intestinal flora and pose a major therapeutic challenge. The possibility of transfer of vancomycin resistance genes to other gram-positive organisms raises significant concerns about the emergence of vancomycin-resistant Staphylococcus aureus. We review VRE, including their history, mechanisms of resistance, epidemiology, control measures, and treatment.

Vancomycin-resistant enterococci

After they were first identified in the mid-1980s, vancomycin-resistant enterococci (VRE) spread rapidly and became a major problem in many institutions both in Europe and the United States. Since VRE have intrinsic resistance to most of the commonly used antibiotics and the ability to acquire resistance to most of the current available antibiotics, either by mutation or by receipt of foreign genetic material, they have a selective advantage over other microorganisms in the intestinal flora and pose a major therapeutic challenge. The possibility of transfer of vancomycin resistance genes to other gram-positive organisms raises significant concerns about the emergence of vancomycin-resistant Staphylococcus aureus. We review VRE, including their history, mechanisms of resistance, epidemiology, control measures, and treatment.

Guideline for Prevention of Surgical Site Infection, 1999. Centers for Disease Control and Prevention (CDC) Hospital Infection Control Practices Advisory Committee

EXECUTIVE SUMMARY The "Guideline for Prevention of Surgical Site Infection, 1999" presents the Centers for Disease Control and Prevention (CDC)'s recommendations for the prevention of surgical site infections (SSIs), formerly called surgical wound infections. This two-part guideline updates and replaces previous guidelines.1,2 Part I, "Surgical Site Infection: An Overview," describes the epidemiology, definitions, microbiology, pathogenesis, and surveillance of SSIs. Included is a detailed discussion of the pre-, intra-, and postoperative issues relevant to SSI genesis. Part II, "Recommendations for Prevention of Surgical Site Infection," represents the consensus of the Hospital Infection Control Practices Advisory Committee (HICPAC) regarding strategies for the prevention of SSIs.3 Whenever possible, the recommendations in Part II are based on data from well-designed scientific studies. However, there are a limited number of studies that clearly validate risk factors and prevention measures for SSI. By necessity, available studies have often been conducted in narrowly defined patient populations or for specific kinds of operations, making generalization of their findings to all specialties and types of operations potentially problematic. This is especially true regarding the implementation of SSI prevention measures. Finally, some of the infection control practices routinely used by surgical teams cannot be rigorously studied for ethical or logistical reasons (e.g., wearing vs not wearing gloves). Thus, some of the recommendations in Part II are based on a strong theoretical rationale and suggestive evidence in the absence of confirmatory scientific knowledge.It has been estimated that approximately 75% of all operations in the United States will be performed in "ambulatory," "same-day," or "outpatient" operating rooms by the turn of the century.4 In recommending various SSI prevention methods, this document makes no distinction between surgical care delivered in such settings and that provided in conventional inpatient operating rooms. This document is primarily intended for use by surgeons, operating room nurses, postoperative inpatient and clinic nurses, infection control professionals, anesthesiologists, healthcare epidemiologists, and other personnel directly responsible for the prevention of nosocomial infections. This document does not: Specifically address issues unique to burns, trauma, transplant procedures, or transmission of bloodborne pathogens from healthcare worker to patient, nor does it specifically address details of SSI prevention in pediatric surgical practice. It has been recently shown in a multicenter study of pediatric surgical patients that characteristics related to the operations are more important than those related to the physiologic status of the patients.5 In general, all SSI prevention measures effective in adult surgical care are indicated in pediatric surgical care. Specifically address procedures performed outside of the operating room (e.g., endoscopic procedures), nor does it provide guidance for infection prevention for invasive procedures such as cardiac catheterization or interventional radiology. Nonetheless, it is likely that many SSI prevention strategies also could be applied or adapted to reduce infectious complications associated with these procedures. Specifically recommend SSI prevention methods unique to minimally invasive operations (i.e., laparoscopic surgery). Available SSI surveillance data indicate that laparoscopic operations generally have a lower or comparable SSI risk when contrasted to open operations.6-11 SSI prevention measures applicable in open operations (e.g., open cholecystectomy) are indicated for their laparoscopic counterparts (e.g., laparoscopic cholecystectomy). Recommend specific antiseptic agents for patient preoperative skin preparations or for healthcare worker hand/forearm antisepsis. Hospitals should choose from products recommended for these activitie

Guideline for prevention of surgical site infection, 1999. Hospital Infection Control Practices Advisory Committee

The “Guideline for Prevention of Surgical Site Infection, 1999” presents the Centers for Disease Control and Prevention (CDC)'s recommendations for the prevention of surgical site infections (SSIs), formerly called surgical wound infections. This two-part guideline updates and replaces previous guidelines.

Part I, “Surgical Site Infection: An Overview,” describes the epidemiology, definitions, microbiology, pathogenesis, and surveillance of SSIs. Included is a detailed discussion of the pre-, intra-, and postoperative issues relevant to SSI genesis.

Elimination of methicillin-resistant Staphylococcus aureus from a neonatal intensive care unit after hand washing with triclosan

Evaluating hand wash products in terms of user acceptability and effectiveness against methicillin-resistant Staphylococcus aureus (MRSA) has been part of a long-term strategy to eliminate endemic MRSA from the neonatal intensive care unit at the Royal Women's Hospital (Brisbane). Following the introduction of a new hand wash disinfectant (triclosan 1% wt/vol), new cases of MRSA colonization were monitored for 12 months. In addition, the use of antibiotics, the incidence of multi-resistant Gram-negative cultures and neonatal infections were noted. No changes were made to any procedures or protocols during the trial. All babies colonized with MRSA had been discharged from the nursery within 7 months of the introduction of triclosan and in the subsequent 9 months no new MRSA isolates had been reported. Reduction in the use of vancomycin has resulted in a cost saving of approximately $A17,000. The total number of Gram-negative isolates has not increased, although Pseudomonas aeruginosa is now reported more often. Compared with the previous 12 months, fewer antibiotics were prescribed and fewer nosocomial infections recorded (P < 0.05).

The antimicrobial activity in vitro of chlorhexidine, a mixture of isothiazolinones ('Kathon' CG) and cetyl trimethyl ammonium bromide (CTAB)

Chlorehexidine, two 4% chlorhexidine antiseptic handwashes ('Bioprep' and 'Hibiclens'), cetyl trimethyl ammonium bromide (CTAB) and isothiazolinones ('Kathon') were tested against Staphylococcus aureus, Micrococcus luteus, Escherichia coli, Serratia marcescens, Pseudomonas aeruginosa, Proteus vulgaris and Candida albicans. The activities measured were the minimum inhibitory concentration (MIC), minimum microbicidal concentration (MMC), rate of kill in water and broth, effect of organic soil, the development of microbial resistance on continuous exposure and agent bioavailability in media and formulation. 'Kathon' was the most active microbistatic agent showing maximal activity at low concentration, least inactivation by organic soil and media components and the lowest level of development of bacterial resistance. It was synergistic with chlorhexidine against S. marcescens and P. aeruginosa. Media, formulation components and organic soil affected the performance of chlorhexidine and CTAB. Chlorhexidine was more broadly active than CTAB but showed a greater reduction in activity in the presence of soil and engendered a greater level of bacterial resistance. It was more rapidly bactericidal to P. aeruginosa and S. marcescens than to S. aureus. Stable resistance to chlorhexidine and CTAB was developed by P. aeruginosa and S. marcescens, the latter showing the higher level of resistance. Chlorhexidine-resistant strains were also resistant to CTAB. The antiseptic formulations were more rapidly bactericidal than chlorhexidine alone but were otherwise of comparable activity. Mixtures of disinfectants, in particular a combination of chlorhexidine and a preservative level of 'Kathon', were more active than single disinfectants. The importance of standardization of media and test conditions and the use of chemically defined media for accurate and reproducible in-vitro testing of disinfectant activity is emphasized. Disinfection kinetics, expressed as time-kill curves, log reduction factors or decimal reduction times were shown to be valuable in differentiating microbistatic from microbicidal activity, showing the effects of dilution and soil on activity and indicating possible different mechanisms of action.

Investigations into the efficacy of different procedures for surgical hand disinfection between consecutive operations

In order to examine whether thorough surgical hand disinfection (handwashing plus hand disinfection) between consecutive operations is necessary, tests were carried out simulating normal clinical conditions. The tests were performed according to the guidelines for the evaluation of disinfection procedures of the German Society for Hygiene and Microbiology. Surgical hand disinfection was as follows: handwashing with soap without antimicrobial additives and subsequent 5-min disinfection with 60% n-propanol. This was followed by simulated operations of 30 or 120 min duration with a 30-min break between operations, during which half of the test group kept on the surgical gloves, while the other half removed them. The second surgical hand disinfection was done without prior handwashing by 50% of the test group. The disinfection time was reduced from 5 to 1 min by 50% of the test group. The results were evaluated by means of explorative data analysis and inductive statistical methods. Removing the surgical gloves during the interoperative break did not result in significantly higher numbers of colony forming units (cfu) compared with retaining the gloves. This was also the case after a subsequent handwashing. At the second surgical hand disinfection, after a simulated operation of 60 min duration (including break), there was no significant difference in the numbers of cfus between the test group who had washed their hands and those who had not. Reducing the disinfection time from 5 min to 1 min was not associated with a significant increase in the number of cfus. However, after a simulated operating time of 150 min (including the break), the second surgical hand disinfection with handwashing resulted in a significantly lower number of microorganisms than disinfection alone. In half the tests, the numbers of cfu were significantly lower when the test group disinfected their hands for 5 min rather than 1 min.

The effect of disinfectants on perforated gloves

Three types of gloves, 'Biogel', 'Regent Dispo Surgical' gloves and Ansell gammex were perforated, and contaminated with Escherichia coli or Pseudomonas aeruginosa as test organisms applied either to the hand or the glove surface. The glove surface was decontaminated with alcoholic chlorhexidine ('Hibisol'), methylated spirit, or soap and water. The experiments were performed in triplicate on three separate days. The experiments were designed to study the ability of the three disinfection methods to reduce the bacterial count of 10(6) colony forming units (cfu) ml-1 (applied to perforated gloves or hands) sufficiently to permit the re-use of such gloves for non-sterile ward procedures. The best method of disinfection was using alcoholic chlorhexidine which not only reduced glove surface carriage but also reduced transfer of bacteria to the hands through the perforation in the gloves. Soap and water was the least effective. Escherichia coli was more easily removed than P. aeruginosa. We recommend that non-sterile ward procedures may be carried out even after gloves have been perforated provided alcoholic chlorhexidine is used between each procedure to reduce cross-infection between patients.