Guideline for Disinfection and Sterilization in
Healthcare Facilities, 2008
( with TwinOxide Update)
( with TwinOxide Update)
On this Page
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Alcohol
Disinfection
Many
disinfectants are used alone or in combinations (e.g., hydrogen peroxide and
peracetic acid) in the health-care setting. These include alcohols, chlorine
and chlorine compounds, formaldehyde, glutaraldehyde, ortho-phthalaldehyde,
hydrogen peroxide, iodophors, peracetic acid, phenolics, and quaternary
ammonium compounds. Commercial formulations based on these chemicals are
considered unique products and must be registered with EPA or cleared by FDA.
In most instances, a given product is designed for a specific purpose and is to
be used in a certain manner. Therefore, users should read labels carefully to
ensure the correct product is selected for the intended use and applied
efficiently.
Disinfectants
are not interchangeable, and incorrect concentrations and inappropriate
disinfectants can result in excessive costs. Because occupational diseases
among cleaning personnel have been associated with use of several disinfectants
(e.g., formaldehyde, glutaraldehyde, and chlorine), precautions (e.g., gloves
and proper ventilation) should be used to minimize exposure 318, 480,
481.
Asthma and reactive airway disease can occur in sensitized persons exposed to
any airborne chemical, including germicides. Clinically important asthma can
occur at levels below ceiling levels regulated by OSHA or recommended by NIOSH.
The preferred method of control is elimination of the chemical (through
engineering controls or substitution) or relocation of the worker.
The following overview of the
performance characteristics of each provides users with sufficient information
to select an appropriate disinfectant for any item and use it in the most efficient
way.
Chemical Disinfectants
Alcohol
Overview. In
the healthcare setting, "alcohol" refers to two water-soluble
chemical compounds—ethyl alcohol and isopropyl alcohol—that have generally
underrated germicidal characteristics 482. FDA
has not cleared any liquid chemical sterilant or high-level disinfectant with
alcohol as the main active ingredient. These alcohols are rapidly bactericidal
rather than bacteriostatic against vegetative forms of bacteria; they also are
tuberculocidal, fungicidal, and virucidal but do not destroy bacterial spores.
Their cidal activity drops sharply when diluted below 50% concentration, and
the optimum bactericidal concentration is 60%–90% solutions in water
(volume/volume) 483, 484.
Mode of
Action. The
most feasible explanation for the antimicrobial action of alcohol is denaturation
of proteins. This mechanism is supported by the observation that absolute
ethyl alcohol, a dehydrating agent, is less bactericidal than mixtures of
alcohol and water because proteins are denatured more quickly in the presence
of water 484, 485. Protein denaturation also is consistent with observations that
alcohol destroys the dehydrogenases of Escherichia coli 486, and that
ethyl alcohol increases the lag phase of Enterobacter aerogenes 487 and
that the lag phase effect could be reversed by adding certain amino acids. The
bacteriostatic action was believed caused by inhibition of the production of
metabolites essential for rapid cell division.
Microbicidal
Activity.
Methyl alcohol (methanol) has the weakest bactericidal action of the alcohols
and thus seldom is used in healthcare 488. The
bactericidal activity of various concentrations of ethyl alcohol (ethanol) was
examined against a variety of microorganisms in exposure periods ranging from
10 seconds to 1 hour 483. Pseudomonas
aeruginosa was killed in 10 seconds by all concentrations of ethanol
from 30% to 100% (v/v), and Serratia marcescens, E, coliand Salmonella
typhosa were killed in 10 seconds by all concentrations of ethanol
from 40% to 100%. The gram-positive organisms Staphylococcus aureus and Streptococcus pyogenes were
slightly more resistant, being killed in 10 seconds by ethyl alcohol
concentrations of 60%–95%. Isopropyl alcohol (isopropanol) was slightly more
bactericidal than ethyl alcohol for E. coli and S.
aureus 489.
Ethyl
alcohol, at concentrations of 60%–80%, is a potent virucidal agent inactivating
all of the lipophilic viruses (e.g., herpes, vaccinia, and influenza virus) and
many hydrophilic viruses (e.g., adenovirus, enterovirus, rhinovirus, and
rotaviruses but not hepatitis A virus (HAV) 58 or poliovirus) 49.
Isopropyl alcohol is not active against the nonlipid enteroviruses but is fully
active against the lipid viruses 72.
Studies also have demonstrated the ability of ethyl and isopropyl alcohol to
inactivate the hepatitis B virus(HBV) 224, 225 and
the herpes virus, 490 and ethyl alcohol to
inactivate human immunodeficiency virus (HIV) 227,
rotavirus, echovirus, and astrovirus 491.
In tests of
the effect of ethyl alcohol against M. tuberculosis, 95% ethanol
killed the tubercle bacilli in sputum or water suspension within 15 seconds 492. In
1964, Spaulding stated that alcohols were the germicide of choice for
tuberculocidal activity, and they should be the standard by which all other
tuberculocides are compared. For example, he compared the tuberculocidal
activity of iodophor (450 ppm), a substituted phenol (3%), and isopropanol
(70%/volume) using the mucin-loop test (106 M.
tuberculosis per loop) and determined the contact times needed for
complete destruction were 120–180 minutes, 45–60 minutes, and 5 minutes,
respectively. The mucin-loop test is a severe test developed to produce long
survival times. Thus, these figures should not be extrapolated to the exposure
times needed when these germicides are used on medical or surgical material 482.
Ethyl
alcohol (70%) was the most effective concentration for killing the tissue phase
ofCryptococcus neoformans, Blastomyces dermatitidis, Coccidioides
immitis, and Histoplasma capsulatumand the culture phases of
the latter three organisms aerosolized onto various surfaces. The culture phase
was more resistant to the action of ethyl alcohol and required about 20 minutes
to disinfect the contaminated surface, compared with <1 minute for the
tissue phase 493, 494.
Isopropyl
alcohol (20%) is effective in killing the cysts of Acanthamoeba culbertsoni (560)
as are chlorhexidine, hydrogen peroxide, and thimerosal 496.
Uses. Alcohols
are not recommended for sterilizing medical and surgical materials principally
because they lack sporicidal action and they cannot penetrate protein-rich
materials. Fatal postoperative wound infections with Clostridium have
occurred when alcohols were used to sterilize surgical instruments contaminated
with bacterial spores 497. Alcohols have been
used effectively to disinfect oral and rectal thermometers 498, 499, hospital
pagers 500, scissors 501, and
stethoscopes 502. Alcohols have been
used to disinfect fiberoptic endoscopes 503, 504 but
failure of this disinfectant have lead to infection 280, 505.
Alcohol towelettes have been used for years to disinfect small surfaces such as
rubber stoppers of multiple-dose medication vials or vaccine bottles.
Furthermore, alcohol occasionally is used to disinfect external surfaces of
equipment (e.g., stethoscopes, ventilators, manual ventilation bags) 506, CPR
manikins 507,
ultrasound instruments508 or medication
preparation areas. Two studies demonstrated the effectiveness of 70%
isopropyl alcohol to disinfect reusable transducer heads in a controlled
environment 509, 510. In contrast, three
bloodstream infection outbreaks have been described when alcohol was used to
disinfect transducer heads in an intensive-care setting 511.
The
documented shortcomings of alcohols on equipment are that they damage the
shellac mountings of lensed instruments, tend to swell and harden rubber and
certain plastic tubing after prolonged and repeated use, bleach rubber and
plastic tiles 482 and damage tonometer
tips (by deterioration of the glue) after the equivalent of 1 working year of
routine use 512. Tonometer biprisms
soaked in alcohol for 4 days developed rough front surfaces that potentially
could cause corneal damage; this appeared to be caused by weakening of the
cementing substances used to fabricate the biprisms 513.
Corneal opacification has been reported when tonometer tips were swabbed with
alcohol immediately before measurement of intraocular pressure 514. Alcohols
are flammable and consequently must be stored in a cool, well-ventilated
area. They also evaporate rapidly, making extended exposure time
difficult to achieve unless the items are immersed.
Overview.
Hypochlorites, the most widely used of the chlorine disinfectants, are
available as liquid (e.g., sodium hypochlorite) or solid (e.g., calcium
hypochlorite). The most prevalent chlorine products in the United States are
aqueous solutions of 5.25%–6.15% sodium hypochlorite (see glossary), usually
called household bleach. They have a broad spectrum of antimicrobial activity,
do not leave toxic residues, are unaffected by water hardness, are inexpensive
and fast acting 328, remove dried or fixed organisms and biofilms from surfaces 465, and have
a low incidence of serious toxicity 515-517.
Sodium hypochlorite at the concentration used in household bleach (5.25-6.15%)
can produce ocular irritation or oropharyngeal, esophageal, and gastric burns 318,
518-522.
Other disadvantages of hypochlorites include corrosiveness to metals in high
concentrations (>500 ppm), inactivation by organic matter, discoloring or
"bleaching" of fabrics, release of toxic chlorine gas when mixed with
ammonia or acid (e.g., household cleaning agents) 523-525, and
relative stability 327. The microbicidal
activity of chlorine is attributed largely to undissociated hypochlorous acid
(HOCl). The dissociation of HOCI to the less microbicidal form (hypochlorite
ion OCl¯) depends on pH. The disinfecting efficacy of chlorine decreases with
an increase in pH that parallels the conversion of undissociated HOCI to OCl¯ 329, 526. A
potential hazard is production of the carcinogen bis(chloromethyl) ether when
hypochlorite solutions contact formaldehyde 527and the
production of the animal carcinogen trihalomethane when hot water is
hyperchlorinated 528. After reviewing environmental fate and ecologic
data, EPA has determined the currently registered uses of hypochlorites will
not result in unreasonable adverse effects to the environment529.
Alternative
compounds that release chlorine and are used in the health-care setting include
demand-release chlorine dioxide, sodium dichloroisocyanurate, and chloramine-T.
The advantage of these compounds over the hypochlorites is that they retain
chlorine longer and so exert a more prolonged bactericidal effect. Sodium
dichloroisocyanurate tablets are stable, and for two reasons, the microbicidal
activity of solutions prepared from sodium dichloroisocyanurate tablets might
be greater than that of sodium hypochlorite solutions containing the same total
available chlorine. First, with sodium dichloroisocyanurate, only 50% of the
total available chlorine is free (HOCl and OCl¯), whereas the remainder is
combined (monochloroisocyanurate or dichloroisocyanurate), and as free
available chlorine is used up, the latter is released to restore the
equilibrium. Second, solutions of sodium dichloroisocyanurate are acidic,
whereas sodium hypochlorite solutions are alkaline, and the more microbicidal
type of chlorine (HOCl) is believed to predominate 530-533.
Chlorine
dioxide-based disinfectants are prepared fresh as required by mixing the two
components (base solution [citric acid with preservatives and corrosion
inhibitors] and the activator solution [sodium chlorite]). In vitro suspension
tests showed that solutions containing about 140 ppm chlorine dioxide achieved
a reduction factor exceeding 106 of S. aureus in 1 minute and of Bacillus
atrophaeus spores in 2.5 minutes in the presence of 3 g/L bovine albumin. The
potential for damaging equipment requires consideration because long-term use
can damage the outer plastic coat of the insertion tube 534. In another study,
chlorine dioxide solutions at either 600 ppm or 30 ppm killed Mycobacterium
avium-intracellulare within 60 seconds after contact but contamination by
organic material significantly affected the microbicidal properties535.
(Here I add an update: We have studied well the production of chlorine dioxide with the help of the Twin oxides method. We are especially manufacturing impressed. To produce the effective biocidal solution two powdered materials are used. These substances are added in a reactor vessel which is filled with water. The effective solution is available after 4 hours. The quality control is performed by a German laboratory. For more information, please contact: info@twinOxide.com and www.twinoxide.com.
Dr.-Ing. Wolfgang Storch
You see the pictures: TwinOxide-Kits)
The microbicidal activity of a
new disinfectant, "superoxidized water," has been examined The concept
of electrolyzing saline to create a disinfectant or antiseptics is appealing
because the basic materials of saline and electricity are inexpensive and the
end product (i.e., water) does not damage the environment. The main products of
this water are hypochlorous acid (e.g., at a concentration of about 144 mg/L)
and chlorine. As with any germicide, the antimicrobial activity of
superoxidized water is strongly affected by the concentration of the active
ingredient (available free chlorine) 536. One manufacturer generates the
disinfectant at the point of use by passing a saline solution over coated
titanium electrodes at 9 amps. The product generated has a pH of 5.0–6.5 and an
oxidation-reduction potential (redox) of >950 mV. Although superoxidized
water is intended to be generated fresh at the point of use, when tested under
clean conditions the disinfectant was effective within 5 minutes when 48 hours
old 537. Unfortunately, the equipment required to produce the product can be
expensive because parameters such as pH, current, and redox potential must be
closely monitored. The solution is nontoxic to biologic tissues. Although the
United Kingdom manufacturer claims the solution is noncorrosive and nondamaging
to endoscopes and processing equipment, one flexible endoscope manufacturer
(Olympus Key-Med, United Kingdom) has voided the warranty on the endoscopes if
superoxidized water is used to disinfect them 538. As with any germicide
formulation, the user should check with the device manufacturer for compatibility
with the germicide. Additional studies are needed to determine whether this
solution could be used as an alternative to other disinfectants or antiseptics
for hand washing, skin antisepsis, room cleaning, or equipment disinfection
(e.g., endoscopes, dialyzers) 400, 539, 540. In October 2002, the FDA cleared
superoxidized water as a high-level disinfectant (FDA, personal communication,
September 18, 2002).
Mode of
Action. The
exact mechanism by which free chlorine destroys microorganisms has not been
elucidated. Inactivation by chlorine can result from a number of factors:
oxidation of sulfhydryl enzymes and amino acids; ring chlorination of amino
acids; loss of intracellular contents; decreased uptake of nutrients;
inhibition of protein synthesis; decreased oxygen uptake; oxidation of
respiratory components; decreased adenosine triphosphate production; breaks in
DNA; and depressed DNA synthesis 329, 347. The actual microbicidal mechanism of
chlorine might involve a combination of these factors or the effect of chlorine
on critical sites 347.
Microbicidal
Activity. Low
concentrations of free available chlorine (e.g., HOCl, OCl-, and elemental
chlorine-Cl2) have a biocidal effect on mycoplasma (25 ppm) and vegetative
bacteria (<5 ppm) in seconds in the absence of an organic load 329, 418.
Higher concentrations (1,000 ppm) of chlorine are required to kill M.
tuberculosis using the Association of Official Analytical Chemists (AOAC)
tuberculocidal test 73. A concentration of 100 ppm will kill ≥99.9% of B.
atrophaeus spores within 5 minutes 541, 542 and destroy mycotic agents in <1
hour 329. Acidified bleach and regular bleach (5,000 ppm chlorine) can
inactivate 106 Clostridium difficile spores in <10 minutes 262. One study reported
that 25 different viruses were inactivated in 10 minutes with 200 ppm available
chlorine 72. Several studies have demonstrated the effectiveness of diluted
sodium hypochlorite and other disinfectants to inactivate HIV 61. Chlorine (500
ppm) showed inhibition of Candida after 30 seconds of exposure 54. In
experiments using the AOAC Use-Dilution Method, 100 ppm of free chlorine killed
106–107 S. aureus, Salmonella choleraesuis, and P. aeruginosa in <10 minutes
327. Because household bleach contains 5.25%–6.15% sodium hypochlorite, or
52,500–61,500 ppm available chlorine, a 1:1,000 dilution provides about 53–62
ppm available chlorine, and a 1:10 dilution of household bleach provides about
5250–6150 ppm.
Data are available for
chlorine dioxide that support manufacturers' bactericidal, fungicidal,
sporicidal, tuberculocidal, and virucidal label claims 543-546. A chlorine
dioxide generator has been shown effective for decontaminating flexible
endoscopes 534 but it is not currently FDA-cleared for use as a high-level
disinfectant 85. Chlorine dioxide can be produced by mixing solutions, such as
a solution of chlorine with a solution of sodium chlorite 329. In 1986, a
chlorine dioxide product was voluntarily removed from the market when its use
caused leakage of cellulose-based dialyzer membranes, which allowed bacteria to
migrate from the dialysis fluid side of the dialyzer to the blood side 547.
Sodium dichloroisocyanurate at
2,500 ppm available chlorine is effective against bacteria in the presence of
up to 20% plasma, compared with 10% plasma for sodium hypochlorite at 2,500 ppm
548. "Superoxidized water" has been tested against bacteria,
mycobacteria, viruses, fungi, and spores 537, 539, 549. Freshly generated
superoxidized water is rapidly effective (<2 minutes) in achieving a 5-log10
reduction of pathogenic microorganisms (i.e., M. tuberculosis, M. chelonae,
poliovirus, HIV, multidrug-resistant S. aureus, E. coli, Candida albicans,
Enterococcus faecalis, P. aeruginosa) in the absence of organic loading.
However, the biocidal activity of this disinfectant decreased substantially in
the presence of organic material (e.g., 5% horse serum) 537, 549, 550. No
bacteria or viruses were detected on artificially contaminated endoscopes after
a 5-minute exposure to superoxidized water 551 and HBV-DNA was not detected
from any endoscope experimentally contaminated with HBV-positive mixed sera
after a disinfectant exposure time of 7 minutes552.
Uses. Hypochlorites
are widely used in healthcare facilities in a variety of settings. 328
Inorganic chlorine solution is used for disinfecting tonometer heads 188 and
for spot-disinfection of countertops and floors. A 1:10–1:100 dilution of
5.25%–6.15% sodium hypochlorite (i.e., household bleach) 22, 228, 553, 554 or
an EPA-registered tuberculocidal disinfectant 17has been recommended for
decontaminating blood spills. For small spills of blood (i.e., drops of blood)
on noncritical surfaces, the area can be disinfected with a 1:100 dilution of
5.25%-6.15% sodium hypochlorite or an EPA-registered tuberculocidal
disinfectant. Because hypochlorites and other germicides are substantially
inactivated in the presence of blood 63, 548, 555, 556, large spills of blood
require that the surface be cleaned before an EPA-registered disinfectant or a
1:10 (final concentration) solution of household bleach is applied 557. If a
sharps injury is possible, the surface initially should be decontaminated 69,
318, then cleaned and disinfected (1:10 final concentration) 63. Extreme care
always should be taken to prevent percutaneous injury. At least 500 ppm
available chlorine for 10 minutes is recommended for decontaminating CPR
training manikins 558. Full-strength bleach has been recommended for
self-disinfection of needles and syringes used for illicit-drug injection when
needle-exchange programs are not available. The difference in the recommended
concentrations of bleach reflects the difficulty of cleaning the interior of
needles and syringes and the use of needles and syringes for parenteral
injection 559. Clinicians should not alter their use of chlorine on
environmental surfaces on the basis of testing methodologies that do not
simulate actual disinfection practices 560, 561. Other uses in healthcare
include as an irrigating agent in endodontic treatment 562 and as a
disinfectant for manikins, laundry, dental appliances, hydrotherapy tanks 23,
41, regulated medical waste before disposal 328, and the water distribution
system in hemodialysis centers and hemodialysis machines 563.
Chlorine long has been used as
the disinfectant in water treatment. Hyperchlorination of a
Legionella-contaminated hospital water system 23 resulted in a dramatic
decrease (from 30% to 1.5%) in the isolation of L. pneumophila from water
outlets and a cessation of healthcare-associated Legionnaires' disease in an
affected unit 528, 564. Water disinfection with monochloramine by municipal
water-treatment plants substantially reduced the risk for healthcare–associated
Legionnaires disease 565, 566. Chlorine dioxide also has been used to control
Legionella in a hospital water supply. 567 Chloramine T 568 and hypochlorites
41 have been used to disinfect hydrotherapy equipment.
Hypochlorite
solutions in tap water at a pH >8 stored at room temperature (23ºC) in
closed, opaque plastic containers can lose up to 40%–50% of their free
available chlorine level over 1 month. Thus, if a user wished to have a
solution containing 500 ppm of available chlorine at day 30, he or she should
prepare a solution containing 1,000 ppm of chlorine at time 0. Sodium hypochlorite
solution does not decompose after 30 days when stored in a closed brown bottle 327.
The use of
powders, composed of a mixture of a chlorine-releasing agent with highly
absorbent resin, for disinfecting spills of body fluids has been evaluated by
laboratory tests and hospital ward trials. The inclusion of acrylic resin
particles in formulations markedly increases the volume of fluid that can be
soaked up because the resin can absorb 200–300 times its own weight of fluid,
depending on the fluid consistency. When experimental formulations containing
1%, 5%, and 10% available chlorine were evaluated by a standardized surface
test, those containing 10% demonstrated bactericidal activity. One problem with
chlorine-releasing granules is that they can generate chlorine fumes when
applied to urine 569.
