Laura Y. Sifuentes

Decreased activity of commercially available disinfectants containing quaternary ammonium compounds when exposed to cotton towels

BACKGROUND Health care-associated infections (HAIs) are a significant problem in hospitals, and environmental surfaces have been implicated as a source of HAIs in the hospital environment. Furthermore, Gram-negative and Gram-positive bacteria can persist on dry environmental surfaces for as long as several months. Poorly cleaned surfaces may serve as vehicles for microbes, which may then be transferred to patients. METHODS Cotton and microfiber towels were both tested for their abilities to bind quaternary ammonium compounds (QACs). The towels were exposed to 3 commercially available disinfectants for 0.5, 30, and 180 minutes. Germicidal spray tests (GSTs) were performed for all towel eluates in accordance with the AOAC International method 961.02. Cotton towel eluates were analyzed for QAC concentration using high-performance liquid chromatography. RESULTS QAC concentrations were reduced by up to 85.3% after exposure to cotton towels, resulting in failure of the disinfectants exposed to cotton towels in 96% of the GSTs. CONCLUSION The use of cotton towels with QAC-based cleansers should be reconsidered, particularly in hospitals where effective cleaning of the patient environment is needed to reduce the risk of HAIs.

The occurrence of Naegleria fowleri in recreational waters in Arizona

Naegleria fowleri is a free-living amoeba found in waters in warmer regions that causes primary amoebic meningoencephalitis, a rare but almost universally fatal disease. The goal of this project was to assess the occurrence of N. fowleri and other thermophilic amoebae in 33 recreational surface waters across Arizona to determine if their presence could be correlated with seasonal or other environmental factors. First, 1-L grab samples were collected over two years and analyzed using polymerase chain reaction and amoebae viability. Seasonality was observed, with N. fowleri and thermophilic amoebae (20% and 30%, respectively) being detected more often in the winter and spring combined than in the summer and fall combined (7.9% and 9.5%, respectively). The spring and fall both had an average temperature of 18°C, yet had different occurrence data (18.2% versus 5.9% for N. fowleri, respectively; 27.3% versus 0% for viable amoebae, respectively). These results are in stark contrast to previous studies in which N. fowleri has been found almost exclusively during warmer months. Over the two-year study, N. fowleri was detected in six and thermophilic amoebae in eight of the 33 recreational water bodies. Five of these were lakes near Phoenix that tested positive for N. fowleri and thermophilic amoebae over multiple seasons. These lakes differed significantly (P ≤ 0.05) from the other 28 surface waters, with a lower average temperature in the spring, a higher temperature in the fall, a higher pH and turbidity in the summer, and a lower electro-conductivity in the spring. They also had lower Escherichia coli and heterotrophic bacteria levels during colder months. Future N. fowleri monitoring in Arizona should focus on these five lakes to further elucidate the factors that contribute to the low occurrence of this amoeba in the summer or which might explain why these lakes appear to be reservoirs for the organism.

Modeling of Human Viruses on Hands and Risk of Infection in an Office Workplace Using Micro-Activity Data

Although the number of illnesses resulting from indirect viral pathogen transmission could be substantial, it is difficult to estimate the relative risks because of the wide variation and uncertainty in human behavior, variable viral concentrations on fomites, and other exposure factors. The purpose of this study was to evaluate the micro-activity approach for assessment of microbial risk by adapting a mathematical model to estimate probability of viral infection from indirect transmission. To evaluate the model, measurements of phage loading on fomites and hands collected before and after implementation of a Healthy Workplace Project intervention were used. Parameter distributions were developed from these data, as well as for micro-activity rates, contact surface areas, phage transfer efficiencies, and inactivation rates. Following the Monte Carlo simulations (n = 1,000), the estimated phage loading on hands was not significantly different from the loading of phage on hands measured in the experimental trials. The model was then used to demonstrate that the Healthy Workplace Project intervention significantly reduced risk of infection by 77% for rotavirus and rhinovirus. This is the first published study to successfully evaluate a model focused on the indirect transmission of viruses via hand contact with measured data and provide an assessment of the micro-activity approach to microbial risk evaluation.

Microbial contamination of hospital reusable cleaning towels

BACKGROUND Hospital cleaning practices are critical to the prevention of nosocomial infection transmission. To this end, cloth towels soaked in disinfectants are commonly used to clean and disinfect hospital surfaces. Cloth cleaning towels have been linked to an outbreak of Bacillus cereus and have been shown to reduce the effectiveness of commonly used quaternary ammonium disinfectants. Thus, it is important to determine whether the reuse of cloth towels increases the risk of pathogen transmission in hospitals. METHODS The goal of this project was to determine the effects of laundry and cleaning practices commonly used in hospitals for washing, storage, and disinfection of cloth cleaning towels on their microbial loads. RESULTS Our results indicate that cloth towels used for cleaning hospital rooms contained high numbers of microbial contaminants. CONCLUSIONS In this case, hospital laundering practices appear insufficient to remove microbial contaminants and may even add contaminants to the towels. Furthermore, it has been previously reported that towels can interfere with the action of common hospital disinfectants. Either independently or in combination, these 2 factors may increase the risk for transmission of pathogens in hospitals. These observations indicate the need to critically reevaluate current hospital cleaning practices associated with reuse of cloth towels.

The healthy workplace project: Reduced viral exposure in an office setting

ABSTRACT Viral illnesses such as gastroenteritis and the common cold create a substantial burden in the workplace due to reduced productivity, increased absenteeism, and increased health care costs. Behaviors in the workplace contribute to the spread of human viruses via direct contact between hands, contaminated surfaces, and the mouth, eyes, and/or nose. This study assessed whether implementation of the Healthy Workplace Project (HWP) (providing hand sanitizers, disinfecting wipes, facial tissues, and use instructions) would reduce viral loads in an office setting of approximately 80 employees after seeding fomites and the hands of volunteer participants with an MS-2 phage tracer. The HWP significantly reduced viable phage detected on participants’ hands, communal fomites, and personal fomites (p ≤ .010) in office environments and presents a cost-effective method for reducing the health and economic burden associated with viral illnesses in the workplace.

Impact of disinfectant wipes on the risk of Campylobacter jejuni infection during raw chicken preparation in domestic kitchens.

In the present study, we conducted a quantitative microbial risk assessment forecasting the exposure to Campylobacter jejuni contaminated surfaces during preparation of chicken fillets and how using a disinfectant‐wipe intervention to clean a contaminated work area decreases the risk of infection following the preparation of raw chicken fillet in a domestic kitchen.

Wide-spectrum activity of a silver-impregnated fabric

Fabrics, such as clothing, drapes, pillowcases, and bedsheets are potential sources of pathogenic bacteria and viruses. We found fabrics (ie, professional clothing, pillowcases, and lab coats) treated with a silver-impregnated material to be effective in significantly reducing a wide spectrum of ordinary and drug-resistant microorganisms, including Salmonella, methicillin-resistant Staphylococcus aureus, Propionibacterium acnes, Trichphyton mentagrophytes, and norovirus. Fabrics impregnated with antimicrobial agents help provide an additional barrier to the transport or reservoir of pathogens in health care environments.

Modeling of ultraviolet light inactivation kinetics of methicillin‐resistant Staphylococcus aureus (MRSA), vancomycin‐resistant Enterococcus (VRE), Clostridium difficile spores and murine norovirus on fomite surfaces

Quantitative data on the doses needed to inactivate micro‐organisms on fomites are not available for ultraviolet applications. The goal of this study was to determine the doses of UV light needed to reduce bacteria and murine norovirus (MNV) on hard surface fomites through experimentation and to identify appropriate models for predicting targeted levels of reduction.

Microbial Load of Reusable Cleaning Towels used in Hospitals

Hospital cleaning practices play a critical role in the prevention of nosocomial infection transmission. To this end, reusable towels soaked in disinfectants are commonly used to clean and disinfect hospital surfaces. There are reports linking reusable cleaning towels to the outbreak of Bacillus cereus. It is known that reusable towels can interfere with the action of commonly used quaternary ammonium disinfectants. It is therefore important to understand if reusable towels can increase the risk for the transmission of pathogens in the hospital. The objective of this study was to investigate the prevalence of bacteria and fungi in reusable cleaning towels. Reusable towels used for cleaning hospital rooms contained high numbers of microbial contaminants. Hospital laundering practices in this study appear to be either insufficient to remove microbial contaminants or even add contaminants to the towels. Furthermore, towels are known to interfere with the action of common hospital grade disinfectants. Independently and together these two factors may increase the risk for transmission of pathogens in the hospital. Importantly, these observations point to the need to critically re-evaluate current hospital cleaning practices associated with the use of reusable towels. Cotton Microfiber p-valuea n Mean n Mean Heterotrophic Bacteria 24 3.17 ± 1.29 6 4.39 ± 0.88 0.0381 Total Coliform 24 0.07 ± 0.23 6 0.78 ± 0.70 0.0002 Aerobic Spore Formers 24 1.66 ± 1.63 6 2.28 ± 1.80 0.4152 Fungi 24 0.12 ± 0.58 6 1.67 ± 1.84 0.0012 Impact of Towel Material on Contamination (log CFU/Towel ± SD) Parameter Heterotrophic Bacteria Total Coliform Aerobic Spore Formers Mean 269 0.15 153 Max 1300 1.3 1320 Min ND ND ND RESULTS Numbers of Towels and Soak Buckets Positive for Microbes Viable Microbes Total Coliform E. coli Aerobic Spore Formers Fungi Towels 28/30a (93%)b 7/30 (23%) 1/30 (3%) 17/30 (56%) 4/30 (13%) Soak Buckets 6/9 (67%) 1/9 (12%) ND 4/9 (44%) ND Microbial Contamination on Reusable Cleaning Towels (Mean log CFU/Towel ± SD; n=3) MATERIALS AND METHODS Hospital survey. Ten hospitals were surveyed regarding their cleaning practices after terminal discharge and the use of disinfectants. Collection of towels. Laundered reusable cleaning towels were collected in triplicate from each hospital. Each collected towel was submerged in buffered peptone water (EMD Chemicals, Gibbstown, NJ) to extract microbes. The peptone broth was extracted from the towel by ringing the liquid out. The extract was assayed on selected media for the isolation of the various bacteria and fungi. Sampling of soak buckets. The buckets used to soak the towels in disinfectants were sampled for 9 of the 10 hospitals. Each soak bucket was swabbed with a Sponge-StickTM Swabs (3MTM, St. Paul, MN) right above the disinfectant liquid line. Microbes were eluted from the Sponge-StickTM Swabs in letheen broth with agitation. The extract was assayed on selected media for the isolation of the various bacteria and fungi. Enumeration of target organisms. Quantitative plate count methods were used to determine the presence of heterotrophic bacteria, total coliform, aerobic spore formers, fungi, Staphylococcus aureus, methicillin resistant S. aureus (MRSA), Escherichia coli, and Clostridium difficile. Identification of organisms. API® strips (bioMerieux, Durham, NC ). Microbial Contamination on Soak Buckets (CFU/100cm2; n=9) Hospital Heterotrophic Bacteria Total Coliform Aerobic Spore Formers Fungi 1 4.1 ± 0.2 0.5 ± 0.5 3.3 ± 0.2 0.9 ± 1.6 2 1.1 ± 1.9 ND 1.7 ± 1.5 ND 3 3.8 ± 0.8 0.3 ± 0.5 1.0 ± 1.7 ND 4 3.9 ± 0.3 ND 1.0 ± 1.7 ND 5 3.5 ± 0.6 ND 1.9 ± 1.6 ND 6 5.0 ± 0.1 1.3 ± 0.5 3.6 ± 0.3 3.3 ± 0.3 7 3.0 ± 0.1 ND ND ND 8 3.7 ± 0.5 ND 1.5 ± 1.3 ND 9 3.8 ± 0.1 ND 3.9 ± 0.6 ND 10 2.3 ± 2.0 ND ND ND ND = Not detected Methicillin resistant Staphylococcus aureus (MRSA) and Clostridium difficile were not isolated from any of the towels or soak buckets.