Impact of prescribed cleaning and disinfectant use on microbial contamination in the home

How extraintestinal pathogenic Escherichia coli (ExPEC) and antimicrobial-resistant E. coli disseminate through the population is undefined. We studied public restrooms for contamination with E. coli and ExPEC in relation to source and extensively characterized the E. coli isolates. For this, we cultured 1,120 environmental samples from 56 public restrooms in 33 establishments (obtained from 10 cities in the greater Minneapolis-St. Paul, MN, metropolitan area in 2003) for E. coli and compared ecological data with culture results. Isolates underwent virulence genotyping, phylotyping, clonal typing, pulsed-field gel electrophoresis (PFGE), and disk diffusion antimicrobial susceptibility testing. Overall, 168 samples (15% from 89% of restrooms) fluoresced, indicating presumptive E. coli: 25 samples (2.2% from 32% of restrooms) yielded E. coli isolates, and 10 samples (0.9% from 16% of restrooms) contained ExPEC. Restroom category and cleanliness level significantly predicted only fluorescence, gender predicted fluorescence and E. coli, and feces-like material and toilet-associated sites predicted all three endpoints. Of the 25 E. coli isolates, 7 (28%) were from phylogenetic group B2(virulence-associated), and 8 (32%) were ExPEC. ExPEC isolates more commonly represented group B2 (50% versus 18%) and had significantly higher virulence gene scores than non-ExPEC isolates. Six isolates (24%) exhibited >3-class antibiotic resistance, 10 (40%) represented classic human-associated sequence types, and one closely resembled reference human clinical isolates by pulsed-field gel electrophoresis. Thus, E. coli, ExPEC, and antimicrobial-resistant E. coli sporadically contaminate public restrooms, in ways corresponding with restroom characteristics and within-restroom sites. Such restroom-source E. coli strains likely reflect human fecal contamination, may pose a health threat, and may contribute to population-wide dissemination of such strains. E scherichia coli is a major cause of urinary tract and other extraintestinal infections, resulting in considerable morbidity, mortality, and costs (1). Most such infections are caused by distinctive E. coli strains called extraintestinal pathogenic E. coli (Ex-PEC) because of their enhanced ability to invade and cause disease at extraintestinal sites (2). Such strains' main reservoir is the human intestinal tract, where they usually reside harmlessly as longterm colonizers (3). ExPEC strains can be distinguished from other E. coli strains by their extensive virulence gene repertoire and primarily group B2 phylogenetic background (2).Dissemination of virulent and antimicrobial-resistant E. coli clones through the human population has been recognized recently as an important contributor to the overall burden of Ex-PEC-associated disease (4-7). However, the mechanisms of such clonal dissemination remain undefined. Flush toilets create microdroplets containing viable bacteria (8, 9), and both public and private restrooms have been shown to be variably contaminated with human-source bacteri...

Section: Discussionmentioning

confidence: 99%

Extraintestinal Pathogenic and Antimicrobial-Resistant Escherichia coli Contamination of 56 Public Restrooms in the Greater Minneapolis-St. Paul Metropolitan Area

Mohamed

Owens

Gajewski

et al. 2015

“…Another study in household kitchens and bathrooms found that a QAC wipe reduced total bacterial numbers by 99.9% overall (15). A study involving 30 households in Mexico showed that the use of a QAC product statistically significantly reduced the occurrence of Escherichia coli on countertops over the 5 weeks of the study (16). In a study conducted in an elementary school, the use of QACbased disinfectant wipes once a day on the desk of each student reduced absenteeism by almost 50% (17).…”

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confidence: 99%

Quaternary Ammonium Biocides: Efficacy in Application

Gerba

2015

461

320

Quaternary ammonium compounds (QACs) are among the most commonly used disinfectants. There has been concern that their widespread use will lead to the development of resistant organisms, and it has been suggested that limits should be place on their use. While increases in tolerance to QACs have been observed, there is no clear evidence to support the development of resistance to QACs. Since efflux pumps are believe to account for at least some of the increased tolerance found in bacteria, there has been concern that this will enhance the resistance of bacteria to certain antibiotics. QACs are membrane-active agents interacting with the cytoplasmic membrane of bacteria and lipids of viruses. The wide variety of chemical structures possible has seen an evolution in their effectiveness and expansion of applications over the last century, including non-lipid-containing viruses (i.e., noroviruses). Selection of formulations and methods of application have been shown to affect the efficacy of QACs. While numerous laboratory studies on the efficacy of QACs are available, relatively few studies have been conducted to assess their efficacy in practice. Better standardized tests for assessing and defining the differences between increases in tolerance versus resistance are needed. The ecological dynamics of microbial communities where QACs are a main line of defense against exposure to pathogens need to be better understood in terms of sublethal doses and antibiotic resistance.

“…A number of studies have shown that enteric and respiratory pathogens are capable of surviving from hours to months on fomites, depending on the numbers deposited, the type of microorganism, and the variable environmental conditions (10)(11)(12). Several studies have shown that inanimate surfaces found in day care centers (8,(13)(14)(15)(16)(17), schools (18), office buildings (19), homes (20)(21)(22)(23)(24)(25)(26)(27), public areas (28), or hospitals (12,(29)(30)(31)(32)(33) can be reservoirs for secondary modes of transmission, with contaminated hands playing a critical role as a route of exposure.…”

mentioning

confidence: 99%

Transfer Efficiency of Bacteria and Viruses from Porous and Nonporous Fomites to Fingers under Different Relative Humidity Conditions

Lopez

Gerba

Tamimi

et al. 2013

213

270

Fomites can serve as routes of transmission for both enteric and respiratory pathogens. The present study examined the effect of low and high relative humidity on fomite-to-finger transfer efficiency of five model organisms from several common inanimate surfaces (fomites). Nine fomites representing porous and nonporous surfaces of different compositions were studied. Escherichia coli, Staphylococcus aureus, Bacillus thuringiensis, MS2 coliphage, and poliovirus 1 were placed on fomites in 10-l drops and allowed to dry for 30 min under low (15% to 32%) or high (40% to 65%) relative humidity. Fomite-to-finger transfers were performed using 1.0 kg/cm 2 of pressure for 10 s. Transfer efficiencies were greater under high relative humidity for both porous and nonporous surfaces. Most organisms on average had greater transfer efficiencies under high relative humidity than under low relative humidity. Nonporous surfaces had a greater transfer efficiency (up to 57%) than porous surfaces (<6.8%) under low relative humidity, as well as under high relative humidity (nonporous, up to 79.5%; porous, <13.4%). Transfer efficiency also varied with fomite material and organism type. The data generated can be used in quantitative microbial risk assessment models to assess the risk of infection from fomite-transmitted human pathogens and the relative levels of exposure to different types of fomites and microorganisms. I nanimate objects, or fomites, are a potential reservoir in the transmission of pathogens either directly, by surface-to-mouth contact, or indirectly, by contamination of fingers and subsequent hand-to-mouth, hand-to-eye, or hand-to-nose contact (1-5). Bodily fluids such as saliva, mucus, nasal secretions, blood, urine, and feces may all potentially contain pathogens that can be transmitted via fomites (6-9). A number of studies have shown that enteric and respiratory pathogens are capable of surviving from hours to months on fomites, depending on the numbers deposited, the type of microorganism, and the variable environmental conditions (10-12). Several studies have shown that inanimate surfaces found in day care centers (8,(13)(14)(15)(16)(17), schools (18), office buildings (19), homes (20-27), public areas (28), or hospitals (12, 29-33) can be reservoirs for secondary modes of transmission, with contaminated hands playing a critical role as a route of exposure.The efficiency of transfer of a pathogen to the hand from the fomite is important in modeling the potential for its transmission (11,(34)(35)(36). This information can be used to understand the spread of disease in indoor environments and the potential for designing surfaces that reduce transfer efficiency and/or are antimicrobial (5). The purpose of this work was to better elucidate the transfer efficiencies of several different types of organisms under control conditions to provide data that may be used in quantitative microbial risk assessment (QMRA) models. (ii) Gram-negative and Gram-positive bacterial inoculum preparation. Frozen aliquots of E. coli an...