Academic journal article Journal of Environmental Health

Microbial Contamination of Ice Machines Is Mediated by Activated Charcoal Filtration Systems in a City Hospital

Academic journal article Journal of Environmental Health

Microbial Contamination of Ice Machines Is Mediated by Activated Charcoal Filtration Systems in a City Hospital

Article excerpt

Introduction

Virtually all hospitals are equipped with machines to provide ice for beverages and for use in ice packs. Microbial contamination of ice machines poses severe health risks to patients undergoing chemotherapy for cancer. Many cancer patients with advanced and terminal-stage disease develop oral stomatitis and dry mouth due to decreased saliva secretion and other side effects of chemotherapeutic agents (Davies, Brailsford, & Beighton, 2001; Davies, Brailsford, & Beighton, 2006; Davies, Brails ford, Beighton, Shorthose, & Stevens, 2008; Jobbins, Bagg, Finlay, Addy, & Newcombe, 1992; Mahood et al., 1991). Cancer patients therefore consume ice both alone and in beverages several times daily for oral cryotherapy.

Although many studies have investigated microbial contamination of ice machines (Graman, Quinlan, & Rank, 1997; Laussucq et al., 1998; Wilson, Hogg, & Barr, 1997), there is virtually no information available regarding microbial contamination of ice machines equipped with activated charcoal (AC) filters, and no comparisons of microbial contamination of ice produced by machines with and without AC filters. Furthermore, most hospitals have no established protocols to evaluate the use of AC filters. We therefore investigated the prevalence of microbial contamination of ice machines with and without AC filters in Shunan City Shinnanyo Municipal Hospital to assess the utility of filtration systems in hygiene management to prevent microbial contamination of ice.

Methods

We investigated the prevalence of microbial contamination in 20 samples of ice cubes produced by each of three ice machines in the hospital. Ice machine 1 was equipped with an AC filter, while 2 and 3 were not. The numbers and types of contaminating microbes were examined in all 60 samples. In addition, we examined the end of the hospital water supply line for microbial contamination and measured the concentration of available chlorine. The investigation was carried out 1 month before the expiration date of the AC filter cartridge. All three ice machines were of the same model and installed at the same time.

Researchers who were wearing sterile gloves collected ice cube samples (about 50 g each) from different locations within each ice bin. The ice was allowed to melt, and the resulting water was immediately used to quantify and identify the microbial load. The samples were serially diluted 10-fold with sterile saline and incubated in trypticase soy agar at 35[degrees]C for 1-7 days. Microorganisms were identified by Gram staining, morphological examination, and oxidation-fermentation and cytochrome oxidase assays; additionally, a test specifically to identify glucose nonfermenting gram-negative rods was performed.

Microbial contamination and the concentration of available chlorine at the end of the water supply line were measured as follows. After tap water from the faucet was allowed to run for at least 3 minutes, the water at the end of the supply line was collected in a sterile container. Immediately after collection, the levels and types of contaminating microbes were determined and the available chlorine concentration was measured against Sibata Chlorine Comparators.

Results

Table 1 shows the microbial contamination of ice made by ice machine 1 (with an AC filter) and ice machines 2 and 3 (without AC filters). All 20 samples from ice machine 1 were contaminated with 10-116 CFUs/g of glucose nonfermenting gram-negative rods (GNF-GNR), which included Pseudomonas aeruginosa, Chryseobacterium meningosepticum, and Sphingomonas paucimobilis. Contamination was <2 CFUs/g (lower detection limit, 2 CFUs/g ice) in all 40 samples collected from ice machines 2 and 3. After the AC filter was removed from contaminated ice machine 1 and the ice was reexamined (n = 20 samples), no contaminants were present. We also examined contamination of residual water in the filter cartridge after removal of the filter (n = 10 samples) and determined the concentration of available chlorine (Table 2). …

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