Guideline for Disinfection and Sterilization in Healthcare Facilities, 2008
Disinfection of HBV-, HCV-, HIV- or TB-Contaminated Devices
The CDC recommendation for high-level disinfection of HBV-, HCV-, HIV- or TB-contaminated devices is appropriate because experiments have demonstrated the effectiveness of high-level disinfectants to inactivate these and other pathogens that might contaminate semicritical devices 61, 62, 73, 81, 105, 121, 125, 221-238. Nonetheless, some healthcare facilities have modified their disinfection procedures when endoscopes are used with a patient known or suspected to be infected with HBV, HIV, or M. tuberculosis 28, 239. This is inconsistent with the concept of Standard Precautions that presumes all patients are potentially infected with bloodborne pathogens228. Several studies have highlighted the inability to distinguish HBV- or HIV-infected patients from noninfected patients on clinical grounds240-242. In addition, mycobacterial infection is unlikely to be clinically apparent in many patients. In most instances, hospitals that altered their disinfection procedure used EtO sterilization on the endoscopic instruments because they believed this practice reduced the risk for infection 28, 239. EtO is not routinely used for endoscope sterilization because of the lengthy processing time. Endoscopes and other semicritical devices should be managed the same way regardless of whether the patient is known to be infected with HBV, HCV, HIV or M. tuberculosis.
An evaluation of a manual disinfection procedure to eliminate HCV from experimentally contaminated endoscopes provided some evidence that cleaning and 2% glutaraldehyde for 20 minutes should prevent transmission 236. A study that used experimentally contaminated hysteroscopes detected HCV by polymerase chain reaction (PCR) in one (3%) of 34 samples after cleaning with a detergent, but no samples were positive after treatment with a 2% glutaraldehyde solution for 20 minutes 120. Another study demonstrated complete elimination of HCV (as detected by PCR) from endoscopes used on chronically infected patients after cleaning and disinfection for 3–5 minutes in glutaraldehyde 118. Similarly, PCR was used to demonstrate complete elimination of HCV after standard disinfection of experimentally contaminated endoscopes 236 and endoscopes used on HCV-antibody–positive patients had no detectable HCV RNA after high-level disinfection 243. The inhibitory activity of a phenolic and a chlorine compound on HCV showed that the phenolic inhibited the binding and replication of HCV, but the chlorine was ineffective, probably because of its low concentration and its neutralization in the presence of organic matter 244.
Disinfection in the Hemodialysis Unit
Hemodialysis systems include hemodialysis machines, water supply, water-treatment systems, and distribution systems. During hemodialysis, patients have acquired bloodborne viruses and pathogenic bacteria 245-247. Cleaning and disinfection are important components of infection control in a hemodialysis center. EPA and FDA regulate disinfectants used to reprocess hemodialyzers, hemodialysis machines, and water-treatment systems.
Noncritical surfaces (e.g., dialysis bed or chair, countertops, external surfaces of dialysis machines, and equipment [scissors, hemostats, clamps, blood pressure cuffs, stethoscopes]) should be disinfected with an EPA-registered disinfectant unless the item is visibly contaminated with blood; in that case a tuberculocidal agent (or a disinfectant with specific label claims for HBV and HIV) or a 1:100 dilution of a hypochlorite solution (500–600 ppm free chlorine) should be used 246, 248. This procedure accomplishes two goals: it removes soil on a regular basis and maintains an environment that is consistent with good patient care. Hemodialyzers are disinfected with peracetic acid, formaldehyde, glutaraldehyde, heat pasteurization with citric acid, and chlorine-containing compounds 249. Hemodialysis systems usually are disinfected by chlorine-based disinfectants (e.g.,sodium hypochlorite), aqueous formaldehyde, heat pasteurization, ozone, or peracetic acid 250, 251. All products must be used according to the manufacturers' recommendations. Some dialysis systems use hot-water disinfection to control microbial contamination.
At its high point, 82% of U.S. chronic hemodialysis centers were reprocessing (i.e., reusing) dialyzers for the same patient using high-level disinfection 249. However, one of the large dialysis organizations has decided to phase out reuse and, by 2002 the percentage of dialysis facilities reprocessing hemodialyzers had decreased to 63% 252. The two commonly used disinfectants to reprocess dialyzers were peracetic acid and formaldehyde; 72% used peracetic acid and 20% used formaldehyde to disinfect hemodialyzers. Another 4% of the facilities used either glutaraldehyde or heat pasteurization in combination with citric acid 252. Infection-control recommendations, including disinfection and sterilization and the use of dedicated machines for hepatitis B surface antigen (HBsAg)-positive patients, in the hemodialysis setting were detailed in two reviews 245, 246. The Association for the Advancement of Medical Instrumentation(AAMI) has published recommendations for the reuse of hemodialyzers253.
Inactivation of Clostridium difficile
The source of health-care–associated acquisition of Clostridium difficile in nonepidemic settings has not been determined. The environment and carriage on the hands of health-care personnel have been considered possible sources of infection 66, 254. Carpeted rooms occupied by a patient with C. difficile were more heavily contaminated with C. difficile than were noncarpeted rooms 255. Because C. difficile spore-production can increase when exposed to nonchlorine-based cleaning agents and the spores are more resistant than vegetative cells to commonly used surface disinfectants256, some investigators have recommended use of dilute solutions of hypochlorite (1,600 ppm available chlorine) for routine environmental disinfection of rooms of patients with C. difficile-associated diarrhea or colitis 257, to reduce the incidence of C. difficile diarrhea 258, or in units with high C. difficile rates. 259 Stool samples of patients with symptomatic C. difficile colitis contain spores of the organism, as demonstrated by ethanol treatment of the stool to reduce the overgrowth of fecal flora when isolating C. difficile in the laboratory260, 261. C. difficile-associated diarrhea rates were shown to have decreased markedly in a bone-marrow transplant unit (from 8.6 to 3.3 cases per 1,000 patient-days) during a period of bleach disinfection (1:10 dilution) of environmental surfaces compared with cleaning with a quaternary ammonium compound. Because no EPA-registered products exist that are specific for inactivating C. difficile spores, use of diluted hypochlorite should be considered in units with high C. difficile rates. Acidified bleach and regular bleach (5000 ppm chlorine) can inactivate 106 C. difficile spores in <10 minutes 262. However, studies have shown that asymptomatic patients constitute an important reservoir within the health-care facility and that person-to-person transmission is the principal means of transmission between patients. Thus, combined use of hand washing, barrier precautions, and meticulous environmental cleaning with an EPA-registered disinfectant (e.g., germicidal detergent) should effectively prevent spread of the organism 263.
Contaminated medical devices, such as colonoscopes and thermometers,can be vehicles for transmission of C. difficile spores 264. For this reason, investigators have studied commonly used disinfectants and exposure times to assess whether current practices can place patients at risk. Data demonstrate that 2% glutaraldehyde 79, 265-267 and peracetic acid 267, 268 reliably kill C. difficile spores using exposure times of 5–20 minutes. ortho-Phthalaldehyde and >0.2% peracetic acid (WA Rutala, personal communication, April 2006) also can inactivate >104 C. difficile spores in 10–12 minutes at 20ºC 268. Sodium dichloroisocyanurate at a concentration of 1000 ppm available chlorine achieved lower log10 reduction factors against C. difficile spores at 10 min, ranging from 0.7 to 1.5, than 0.26% peracetic acid with log10 reduction factors ranging from 2.7 to 6.0268.
OSHA Bloodborne Pathogen Standard
In December 1991, OSHA promulgated a standard entitled "Occupational Exposure to Bloodborne Pathogens" to eliminate or minimize occupational exposure to bloodborne pathogens 214. One component of this requirement is that all equipment and environmental and working surfaces be cleaned and decontaminated with an appropriate disinfectant after contact with blood or other potentially infectious materials. Even though the OSHA standard does not specify the type of disinfectant or procedure, the OSHA original compliance document 269 suggested that a germicide must be tuberculocidal to kill the HBV. To follow the OSHA compliance document a tuberculocidal disinfectant (e.g., phenolic, and chlorine) would be needed to clean a blood spill. However, in February 1997, OSHA amended its policy and stated that EPA-registered disinfectants labeled as effective against HIV and HBV would be considered as appropriate disinfectants ". . . provided such surfaces have not become contaminated with agent(s) or volumes of or concentrations of agent(s) for which higher level disinfection is recommended." When bloodborne pathogens other than HBV or HIV are of concern, OSHA continues to require use of EPA-registered tuberculocidal disinfectants or hypochlorite solution (diluted 1:10 or 1:100 with water) 215, 228. Studies demonstrate that, in the presence of large blood spills, a 1:10 final dilution of EPA-registered hypochlorite solution initially should be used to inactivate bloodborne viruses 63, 235 to minimize risk for infection to health-care personnel from percutaneous injury during cleanup.
Emerging Pathogens (Cryptosporidium, Helicobacter pylori, Escherichia coli O157:H7, Rotavirus, Human Papilloma Virus, Norovirus, Severe Acute Respiratory Syndrome [SARS] Coronavirus)
Emerging pathogens are of growing concern to the general public and infection-control professionals. Relevant pathogens include Cryptosporidium parvum, Helicobacter pylori, E. coli O157:H7, HIV, HCV, rotavirus, norovirus, severe acute respiratory syndrome (SARS) coronavirus, multidrug-resistant M. tuberculosis, and nontuberculous mycobacteria (e.g., M. chelonae). The susceptibility of each of these pathogens to chemical disinfectants and sterilants has been studied. With the exceptions discussed below, all of these emerging pathogens are susceptible to currently available chemical disinfectants and sterilants 270.
Cryptosporidium is resistant to chlorine at concentrations used in potable water. C. parvum is not completely inactivated by most disinfectants used in healthcare including ethyl alcohol 271, glutaraldehyde 271, 272, 5.25% hypochlorite 271, peracetic acid 271, ortho-phthalaldehyde 271, phenol 271, 272, povidone-iodine 271, 272, and quaternary ammonium compounds271. The only chemical disinfectants and sterilants able to inactivate greater than 3 log10 of C. parvum were 6% and 7.5% hydrogen peroxide 271. Sterilization methods will fully inactivate C. parvum, including steam 271, EtO 271, 273, and hydrogen peroxide gas plasma271. Although most disinfectants are ineffective against C. parvum, current cleaning and disinfection practices appear satisfactory to prevent healthcare-associated transmission. For example, endoscopes are unlikely to be an important vehicle for transmitting C. parvum because the results of bacterial studies indicate mechanical cleaning will remove approximately 104 organisms, and drying results in rapid loss of C. parvum viability (e.g., 30 minutes, 2.9 log10 decrease; and 60 minutes, 3.8 log10 decrease) 271.
Chlorine at ~1 ppm has been found capable of eliminating approximately 4 log10 of E. coli O157:H7 within 1 minute in a suspension test64. Electrolyzed oxidizing water at 23oC was effective in 10 minutes in producing a 5-log10 decrease in E. coli O157:H7 inoculated onto kitchen cutting boards274. The following disinfectants eliminated >5 log10 of E. coli O157:H7 within 30 seconds: a quaternary ammonium compound, a phenolic, a hypochlorite (1:10 dilution of 5.25% bleach), and ethanol53. Disinfectants including chlorine compounds can reduce E. coli O157:H7 experimentally inoculated onto alfalfa seeds or sprouts 275, 276 or beef carcass surfaces277.
Data are limited on the susceptibility of H. pylori to disinfectants. Using a suspension test, one study assessed the effectiveness of a variety of disinfectants against nine strains of H. pylori 60. Ethanol (80%) and glutaraldehyde (0.5%) killed all strains within 15 seconds; chlorhexidine gluconate (0.05%, 1.0%), benzalkonium chloride (0.025%, 0.1%), alkyldiaminoethylglycine hydrochloride (0.1%), povidone-iodine (0.1%), and sodium hypochlorite (150 ppm) killed all strains within 30 seconds. Both ethanol (80%) and glutaraldehyde (0.5%) retained similar bactericidal activity in the presence of organic matter; the other disinfectants showed reduced bactericidal activity. In particular, the bactericidal activity of povidone-iodine (0.1%) and sodium hypochlorite (150 ppm) markedly decreased in the presence of dried yeast solution with killing times increased to 5 - 10 minutes and 5 - 30 minutes, respectively.
Immersing biopsy forceps in formalin before obtaining a specimen does not affect the ability to culture H. pylori from the biopsy specimen 278. The following methods are ineffective for eliminating H. pylori from endoscopes: cleaning with soap and water 119, 279, immersion in 70% ethanol for 3 minutes280, instillation of 70% ethanol126, instillation of 30 ml of 83% methanol279, and instillation of 0.2% Hyamine solution281. The differing results with regard to the efficacy of ethyl alcohol against Helicobacter are unexplained. Cleaning followed by use of 2% alkaline glutaraldehyde (or automated peracetic acid) has been demonstrated by culture to be effective in eliminating H. pylori 119, 279, 282. Epidemiologic investigations of patients who had undergone endoscopy with endoscopes mechanically washed and disinfected with 2.0%–2.3% glutaraldehyde have revealed no evidence of person-to-person transmission of H. pylori 126, 283. Disinfection of experimentally contaminated endoscopes using 2% glutaraldehyde (10-minute, 20-minute, 45-minute exposure times) or the peracetic acid system (with and without active peracetic acid) has been demonstrated to be effective in eliminating H. pylori 119. H. pylori DNA has been detected by PCR in fluid flushed from endoscope channels after cleaning and disinfection with 2% glutaraldehyde 284. The clinical significance of this finding is unclear. In vitro experiments have demonstrated a >3.5-log10 reduction in H. pylori after exposure to 0.5 mg/L of free chlorine for 80 seconds285.
An outbreak of healthcare-associated rotavirus gastroenteritis on a pediatric unit has been reported 286. Person to person through the hands of health-care workers was proposed as the mechanism of transmission. Prolonged survival of rotavirus on environmental surfaces (90 minutes to >10 days at room temperature) and hands (>4 hours) has been demonstrated. Rotavirus suspended in feces can survive longer 287, 288. Vectors have included hands, fomites, air, water, and food 288, 289. Products with demonstrated efficacy (>3 log10 reduction in virus) against rotavirus within 1 minute include: 95% ethanol, 70% isopropanol, some phenolics, 2% glutaraldehyde, 0.35% peracetic acid, and some quaternary ammonium compounds 59, 290-293. In a human challenge study, a disinfectant spray (0.1% ortho-phenylphenol and 79% ethanol), sodium hypochlorite (800 ppm free chlorine), and a phenol-based product (14.7% phenol diluted 1:256 in tapwater) when sprayed onto contaminated stainless steel disks, were effective in interrupting transfer of a human rotavirus from stainless steel disk to fingerpads of volunteers after an exposure time of 3- 10 minutes. A quaternary ammonium product (7.05% quaternary ammonium compound diluted 1:128 in tapwater) and tapwater allowed transfer of virus 52.
No data exist on the inactivation of HPV by alcohol or other disinfectants because in vitro replication of complete virions has not been achieved. Similarly, little is known about inactivation of noroviruses (members of the family Caliciviridae and important causes of gastroenteritis in humans) because they cannot be grown in tissue culture. Improper disinfection of environmental surfaces contaminated by feces or vomitus of infected patients is believed to play a role in the spread of noroviruses in some settings 294-296. Prolonged survival of a norovirus surrogate (i.e., feline calicivirus virus [FCV], a closely related cultivable virus) has been demonstrated (e.g., at room temperature, FCV in a dried state survived for 21–18 days) 297. Inactivation studies with FCV have shown the effectiveness of chlorine, glutaraldehyde, and iodine-based products whereas the quaternary ammonium compound, detergent, and ethanol failed to inactivate the virus completely. 297 An evaluation of the effectiveness of several disinfectants against the feline calicivirus found that bleach diluted to 1000 ppm of available chlorine reduced infectivity of FCV by 4.5 logs in 1 minute. Other effective (log10 reduction factor of >4 in virus) disinfectants included accelerated hydrogen peroxide, 5,000 ppm (3 min); chlorine dioxide, 1,000 ppm chlorine (1 min); a mixture of four quaternary ammonium compounds, 2,470 ppm (10 min); 79% ethanol with 0.1% quaternary ammonium compound (3 min); and 75% ethanol (10 min) 298. A quaternary ammonium compound exhibited activity against feline calicivirus supensions dried on hard surface carriers in 10 minutes 299. Seventy percent ethanol and 70% 1-propanol reduced FCV by a 3–4-log10 reduction in 30 seconds 300.
CDC announced that a previously unrecognized human virus from the coronavirus family is the leading hypothesis for the cause of a described syndrome of SARS 301. Two coronaviruses that are known to infect humans cause one third of common colds and can cause gastroenteritis. The virucidal efficacy of chemical germicides against coronavirus has been investigated. A study of disinfectants against coronavirus 229E found several that were effective after a 1-minute contact time; these included sodium hypochlorite (at a free chlorine concentration of 1,000 ppm and 5,000 ppm), 70% ethyl alcohol, and povidone-iodine (1% iodine) 186. In another study, 70% ethanol, 50% isopropanol, 0.05% benzalkonium chloride, 50 ppm iodine in iodophor, 0.23% sodium chlorite, 1% cresol soap and 0.7% formaldehyde inactivated >3 logs of two animal coronaviruses (mouse hepatitis virus, canine coronavirus) after a 10-minute exposure time 302. The activity of povidone-iodine has been demonstrated against human coronaviruses 229E and OC43 303. A study also showed complete inactivation of the SARS coronavirus by 70% ethanol and povidone-iodine with an exposure times of 1 minute and 2.5% glutaraldehyde with an exposure time of 5 minute 304. Because the SARS coronavirus is stable in feces and urine at room temperature for at least 1–2 days (WHO, 2003; http://www.who.int/csr/sars/survival_2003_05_04/en/index.html), surfaces might be a possible source of contamination and lead to infection with the SARS coronavirus and should be disinfected. Until more precise information is available, environments in which SARS patients are housed should be considered heavily contaminated, and rooms and equipment should be thoroughly disinfected daily and after the patient is discharged. EPA-registered disinfectants or 1:100 dilution of household bleach and water should be used for surface disinfection and disinfection on noncritical patient-care equipment. High-level disinfection and sterilization of semicritical and critical medical devices, respectively, does not need to be altered for patients with known or suspected SARS.
Free-living amoeba can be pathogenic and can harbor agents of pneumonia such as Legionella pneumophila. Limited studies have shown that 2% glutaraldehyde and peracetic acid do not completely inactivate Acanthamoeba polyphaga in a 20-minute exposure time for high-level disinfection. If amoeba are found to contaminate instruments and facilitate infection, longer immersion times or other disinfectants may need to be considered 305.