(The main page on viability and susceptibility of micro-organisms to disinfectants is here)
Contents
- Data on the persistence and the susceptibility to disinfectants of some viruses
- Data on the persistence and the susceptibility to disinfectants of some bacteria
- Data on the persistence and the susceptibility to disinfectants of some parasites
(Last revised: January 23, 2013)
1. Data on the persistence and the susceptibility to disinfectants of some viruses
Avian Influenza viruses, Hepatitis A Virus, Hepatitis B Virus, Hepatitis C virus, Human Immunodeficiency viruses, Puumala Hantavirus.
The data provided (when available in the litterature) for each pathogenic organisms listed below are the following: Transmission, persistence, infectious dose, inactivation
1.1. Avian influenza viruses, Influenza A viruses, High pathogenicity avian influenza (HPAI) viruses: H5 or H7 and Low pathogenicity avian influenza viruses (LPAI)
Transmission: Through contact with dead or sick birds by inhalation of infectious droplets or airborne droplet nuclei and possibly by indirect contact followed by self-inoculation of infectious virus into the upper respiratory tract or conjunctive mucosa. Infection through ingestion of HPAI H5N1 viruses has been reported in animals but rarely in humans. Infection across intact skin has not been described. Other routes of transmission should also be considered resulting from laboratory manipulations such as the faecal-oral route with infected animal faeces, mechanical transmission, and exposure to droplets of respiratory animal secretions.
Survival: influenced by temperature, pH, salinity and the presence of organic material. These viruses cannot survive for a long time in a dry environment but persist for a long period in aquatic environments, best at low temperatures, in fresh or brackish water rather than salt water, 4 weeks at 18°C.
LPAI: persist in distilled water > 100 days at 28°C, 200 days at 17°C, 35 days in peptone water at 4°C, 30°C or 37°C.
HPAI: > 100 days at 17°C in fresh water, 26-30 days at 28°C.
Persistence in faeces: LPAI (H7N2) viruses persist 2 weeks in faeces and on cages, 32 days at 15-20°C, 20 days at 28-30°C, inactivated more quickly when mixed with chicken manure.
In other studies LPAI viruses were reported to survive for 44 or 105 days in faeces.
Infectious dose: Unknown. Lethal cases that have been reported for human infection by wild influenza A (H5N1) are most likely caused by high doses of virus inhaled by people who are living in very close contact with infected poultry.
Inactivation: influenza viruses are susceptible to a wide variety of disinfectants including sodium hypochlorite, 70% ethanol, oxidizing agents, quaternary ammonium compounds, aldehydes (formalin, glutaraldehyde, formaldehyde), phenols, acids, povidone-iodine and lipid solvents. They can also be inactivated by heating to 56°C for a minimum of 60 min, as well as by ionizing radiation or low pH (pH2). Avian influenza viruses seem to be more resistant to high temperatures and low pH than mammalian influenza viruses.
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Transmission: Ingestion, contact with mucous membranes (splashes, aerosols). A good vaccine exists and provides adequate protection.
Survival: 2 h – 60 days on inanimate surfaces at lab conditions.
The HAV is relatively hardy. HAV can survive in contact with certain acids and some heat. For a period of time and under certain conditions, HAV can survive in sea water, dried faeces and live oysters. HAV survival was inversely proportional to the level of RH (relative humidity) and temperature, and the half-lives of the virus ranged from greater than 7 days at the low RH and 5°C to about 2 h at the ultrahigh RH and 35°C.
Infectious dose: 10-100 virus (estimated)
Inactivation: non-enveloped RNA virus.
HAV disinfection was assessed on contaminated stainless-steel disks and then covered with 20 µl a test product for 1 min. 20 products were tried and tested. Of the 20 formulations tested, only:
- 2% glutaraldehyde;
- A quaternary ammonium formulation containing 23% HCl (toilet bowl cleaner), sodium hypochlorite (greater than 5 of free chlorine) reduced the virus titer by greater than 99.9%;
- Phenolics, iodine-based products, alcohols, and solutions of acetic, peracetic, citric, and phosphoric acids were unable to do so.
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Transmission: Parenteral inoculation; droplet and aerosol exposure of mucous membranes; contact exposure of broken skin. Hepatitis B is preventable with a safe and effective vaccine.
Survival: The HBV can still be infectious for up to one week outside the body.
Infectious dose: Unknown.
Inactivation: Enveloped DNA virus.
- Similar to HCV for disinfection.
- Manufacturers of hydrogen peroxide warn that it requires contact for at least 5 min to be effective. Hydrogen peroxide together with peracetic acid have high disinfectant qualities.
- Glutaraldehyde, ortho-phthalaldehyde and formaldehyde kill HBV (used for sterilization).
- 1% sodium hypochlorite for several min.
- Ethyl and isopropyl alcohol are effective in killing HBV. The contact time needed difficult to achieve because alcohol (70% ethanol) evaporates quickly.
- Iodine and iodophors. Iodine tinctures are effective, but require long contact time.
- Phenolic disinfectants are effective in killing HBV and are safe to use.
- Quaternary ammonium compounds are ineffective as antiseptics on skin and tissues but are effective in killing the HBV.
Findings suggest that disinfectant chemicals ranging in activity levels from intermediate (e.g., isopropyl alcohol) to high (e.g., 2% aqueous glutaraldehyde), were all shown to be effective against HBV under a "worst-case" situation (dried plasma, 20°C, 10 min). This suggests that any chemical germicide having an activity level in this range might also be used on HBV contamination with a margin of safety, provided that the chemical is properly used.
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Transmission: Parenteral inoculation; droplet and aerosol exposure of mucous membranes; contact exposure of broken skin.
Survival:
- Infectious HCV can persist as a dried sample for up to 1 week.
- HCV in suspension could survive for 3 weeks.
- In syringes infectivity was detected for up to 63 days.
Viability outside the body, however, can vary widely depending on conditions. Viruses survive longer on hard surfaces such as stainless steel and less time on soft surfaces like fabric. It can survive sometimes for weeks in favourable conditions outside the body.
Infectious dose: Unknown.
Inactivation: Enveloped RNA virus - 50 nm diameter (small).
- 1-propanol, reducing viral titers to background levels at a concentration of 30% at 1 min, 2-propanol, a concentration of 50% obtains and complete inactivation at 1 min exposure (40% concentration: 5 min exposure);
- Ethanol at least 50% concentration necessary, 5 min exposure necessary. So ethanol is less effective than propanol, with 1-propanol being more effective than 2-propanol;
- Commercially available disinfectants like glutaraldehyde, quaternary ammonium, and peroxide compounds have a high virucidal efficacy against HCV.
HCV could be eliminated at temperatures of 65–70°C.
1.5. Human Immunodeficiency viruses 1 & 2 (HIV)
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Transmission: Parenteral inoculation; droplet and aerosol exposure of mucous membranes; contact exposure of broken skin.
Survival: Drying in environment causes rapid (within several hours) 90-99% reduction in HIV concentration. HIV can remain viable in blood in syringes at room temperature for many days, and in blood and cerebrospinal fluid from autopsies for up to 11 days. Cell-free HIV dried onto a glass coverslip in 10% serum can survive for longer than 7 days, depending on the initial titer.
Infectious dose: Unknown.
Inactivation:Enveloped RNA virus.
HIV is susceptible to:
- Fresh 2% glutaraldehyde, 2% Jodopax (detergent and iodine), Sodium hypochlorite, Peracetic acids, Peroxygens, Iodine, Phenolics;
- To a lesser extent 70% ethanol (because of quick evaporation);
- NaOH and isopropanol.
Assays showed that active constituents including glutaraldehyde, chlorine, phenolics, alcohol, iodine and quaternary ammonium compounds completely inactivated cell-free HIV following a 1 min exposure.
However, cell-associated HIV suspended in medium or whole humanblood is found to be more resistant, requiring exposure of 5 min or more for some disinfectants. The effectiveness of the disinfectants was further compromised in the presence of blood.
1.6. Puumala Hantavirus (PUUV)
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Transmission: Inhalation of aerosolized droplets or particles ingestion, contact of mucous membranes or broken skin with infectious materials, animal bites, and accidental parenteral inoculation.
Survival: Infectivity of PUUV has been reported to persist in neutral solutions for several hours at 37°C and for several days at lower temperatures as well as in dried cell cultures for up to 2 days.
Wild-type PUUV excreted maintained its infectivity to recipient voles at room temperature (RT) for 12-15 days. In cell culture supernatants, PUUV remained infectious for 5-11 days at RT and up to 18 days at 4°C, but were inactivated after 24h at 37°C. Interestingly, a fraction of dried virus was still infectious after 1 h at 56°C.
Infectious dose: Unknown.
Inactivation: Enveloped RNA virus.
- Inactivation of PUUV after 10 min: Chlorine dioxide (1%), Dettol® (1%), Halamid-D® (1%), peracetic acid (1%), sodium hypochlorite (1%), Virkon® (1%), methanol.
- Ethanol 70% only after 30 min.
- Also chloroform and paraformaldehyde have been proven successful.
Legend:
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H: Human pathogen, A: Animal pathogen, n: Class of risk or Risk group
(*) Micro-organisms of risk group 3 that may present a limited risk of infection for humans and animals because they are not normally infectious by the airborne route.
2. Data on the persistence and the susceptibility to disinfectants of some bacteria
Bacillus anthracis, Brucella spp., Campylobacter jejuni, Chlamydia psittaci, Clostridium difficile, Coxiella burnetii, E. coli enterohemorrhagic, Francisella tularensis, Haemophilus influenza, Legionella pneumophila, Mycobacterium tuberculosis, Neisseria meningitidis, Salmonella typhi, Shigella spp., Staphylococcus aureus
The data provided (when available in the litterature) for each pathogenic organisms listed below are the following: Transmission, persistence, infectious dose, inactivation
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Transmission: The primary hazards to laboratory personnel are direct and indirect contact of intact and broken skin with cultures and accidental parenteral inoculation. Exposure to infectious aerosols is an additional hazard associated with the screening of environmental samples.
Survival: spores can be stable for very long times. In soil, for +/- 40 years.
Infectious dose: Inhalation LD50: 600 - 2200 spores or 8000-50000 spores.
It is suggested that 100 spores may be sufficient to cause infection and a more recent analysis suggested that as few as 1–3 spores may be sufficient to cause infection.
Inactivation: Aerobic, large Gram positive rods occurring in chains; non-motile; forms endospores
Spores are resistant to many disinfectants. For eradicating spores sterilization is needed.
- Susceptible to 2% glutaraldehyde, formaldehyde and 5% formalin (overnight soak preferable).
- Hydrogen peroxide (1000 ppm) is effective (but still research is needed).
- Gaseous forms of chlorine dioxide, ethylene oxide, formaldehyde, hydrogen peroxide, methylene bromide, ozone, peracetic acid and propylene oxide have been used for the inactivation of B. anthracis spores.
- Some reports mention a >6 log10 reduction of B. anthracis spores in 5 min with acidified bleach (5,250 ppm chlorine).
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Transmission: Exposure to aerosols; direct skin contact with cultures of infectious specimens from animals; ingestion; accidental inoculation; sprays into eyes, nose and mouth (exposure to mucous membranes).
Survival: Brucella spp. can survive for long periods in dust, dung, water, slurry, aborted foetuses, soil, meat and dairy products. The precise duration of survival is dependent on many variables such as the nature of the substrate, number of organisms, temperature, pH, sunlight, the presence of other microbial contaminants.
B. abortus can survive in Tap water at -4°C for 114 days. On solid surface at 31°C and in direct sunlight, survival of 4-5 hours. In dried soil samples at room temperature (20 °C) survival is less than 4 days.
B. melitensis can survive in milk at 37 °C for about 7–24 h.
Brucella dies off fairly rapidly when the acidity drops below pH 4, and very rapidly below pH 3.5
Infectious dose: Unknown, it is assumed that blood samples and biopsy material for either serological or bacteriological diagnosis will rarely contain Brucella in sufficient numbers to present a significant risk to personnel handling them.
However, after Brucella has grown in culture, dangerous numbers of organisms are present. Clotted blood samples present little risk and milk samples only a slight risk. Membranes, fetal tissues and fluids may contain up to >109 Brucella cells per gram.
Inactivation: Gram negative cocci or small rods, aerobic, non-motile, non sporulating
Disinfectants reported to destroy Brucella on contaminated surfaces include:
- 2.5% sodium hypochlorite,
- 2-3% caustic soda (NaOH),
- 20% freshly slaked lime suspension,
- 2% formaldehyde solution (all tested for 1h).
- Ethanol, isopropanol, iodophores, substituted phenols or diluted hypochlorite solutions can be used on contaminated skin. Alkyl quaternary ammonium compounds are not recommended for this purpose.
- Xylene (1ml/l) and calcium cyanamide (20 kg/m3) are reported to decontaminate liquid manure after 2 to 4 weeks.
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Transmission: Ingestion, parenteral inoculation.
Survival: Up to 6 days on inanimate surfaces at laboratory conditions.
Infectious dose: ≤ 500 organisms by ingestion.
Inactivation:
Studies demonstrated that at an inoculum size of 103 to 104 CFU/ml, 1.25 mg/l of hypochlorite killed three strains within 1 min. At an inoculumsize of 106 to 107 CFU/ml, 5 mg/l of hypochlorite (5 ppm) killed three strains within 15 min.
At the high inoculum, 0.15% phenolic compound, 10mg/l of iodophor, 1:50,000 quaternary ammonium compound,70% ethyl alcohol, and 0.125% glutaraldehyde killed all threestrains within 1 min.
2.4. Chlamydia psittaci (avian strain)
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Transmission: Infectious aerosols and droplets created during the handling of infected birds or infected tissues.
Survival: Infected fluid from eggs: 52 hours, bird droppings: a few days, bird feed: 2 months, glass: 15 days, straw: 20 days. The organism is environmentally labile but can remain infectious for over a month if protected by organic debris (e.g., litter and faeces).
Infectious dose: Unknown. All people are considered susceptible, though older adults may be more severely affected.
Inactivation: nonmotile, gram-negative.
Because C. psittaci has a high lipid content, it is susceptible to most disinfectants and detergents:
- A 1:1000 dilution of quaternary ammonium compounds,
- 70% isopropyl alcohol,
- 1% lysol,
- A 1:100 dilution of household bleach,
- Chlorophenols.
However, this pathogen is resistant to acids and alkali.
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Transmission: Ingestion, parenteral inoculation. Via fomites and hands.
Survival:Spores can survive for 5 months on dry inanimate surfaces.
Infectious dose: Unknown.
Inactivation: Gram positive rod, anaerobic, motile, subterminal spores, produces a cytotoxin and enterotoxin
Sodium hypochlorite is effective in eliminating C. difficile from a hospital environment.
Spores are fairly resistant; moderate susceptibility to 1% sodium hypochlorite; but they are susceptible to high level disinfectants (>2% glutaraldehyde) with prolonged contact time. 10% bleach can be used for environmental disinfection. Some investigators have recommended use of dilute solutions of hypochlorite (1,600 ppm available chlorine).
The chlorine-releasing agent Actichlor was found to be suitable for the elimination of C. difficile spores from laboratory surfaces. According to the CDC, acidified bleach and regular bleach (5000 ppm chlorine) can inactivate 106 C. difficile spores in <10 min.
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Transmission: Mainly via inhalation of contaminated aerosols from amniotic fluid, placenta, or contaminated wool from farm animals (airborne organism may be carried miles downwind). Exposure to infectious aerosols, ingestion, or accidental parenteral inoculation. Among the “top 10” organisms for having caused LAIs.
Survival: C. burnetii can withstand harsh environmental conditions. It can survive at 15-20°C for 10 months, on meat in cold storage for more than 1 month, in skim milk at RT for more than 40 months. It can also survive in soil, contaminated buildings, food and fomites for years. C. burnetii is known to be resistant to physical stresses, such as elevated temperature, desiccation, osmotic shock and UV light, and to chemical stresses, such as disinfectants, which contributes to its stability in the environment.
Infectious dose: ±10 organisms.
Inactivation: Gram-negative, spore-forming coccobacillus.
- 2% formaldehyde, 1% Lysol, 5% hydrogen peroxide, 70% ethanol, 5% chloroform, hypochlorite (5000 ppm available chlorine).
Although areas thought to be contaminated could be assessed for presence of C. burnetii DNA by PCR, determining viability would be difficult, and combined with the organism’s resistance to chemical disinfectants, assessing decontamination efficacy would be difficult.
Liquid suspensions of the bacteria have been shown to be inactivated completely by:
- 70% ethyl alcohol,
- 5% chloroform,
- 5% Enviro-Chem (a chloric compound) within 30 minutes,
…but not by 0.5% sodium hypochlorite, 5% Lysol, 5% formalin, or 2% Roccal (alkyl dimethyl benzyl ammonium chloride, 10%; ethyl alcohol, 1.25%) even after 24 hours.
- Overnight exposure to formaldehyde or ethylene gas can inactivate C. burnetii within a small, sealed humidified chamber and formaldehyde vapour was effective when a high relative humidity was maintained, but not in a large room without humidity control.
2.7. E. coli enterohemorrhagic (EHEC)
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Transmission: Ingestion or accidental parenteral inoculation.
Survival: E. coli O157: 1.5 hours – 16 months on inanimate surfaces in lab conditions. E. coli O157:H7 is capable of surviving for prolonged periods of time in soil, meats, and produce.
Persistence is great on moist samples under cooler (5-20°C) temperatures. e.g., inoculated onto lettuce, E. coli O157:H7 was demonstrated to survive at 4°C for up to 15 days, up to 144 hours in untreated milk held at 7°C.
Findings indicate that E. coli O157 has the potential to persist for long periods of time on gates, stiles and other farmyard surfaces under a range of environmental conditions with survival greater on wood than on galvanized steel.
Infectious dose: Appears to have low infectious dose, 10 organisms by ingestion.
Inactivation: Gram-negative bacteria.
Susceptible to many disinfectants:
-1% sodium hypochlorite, Chlorine at 1 ppm has been found capable of eliminating approximately 4 log10 of E. coli O157:H7 within 1 min in a suspension test. Also tested: a hypochlorite (1:10 dilution of 5.25% bleach),
- 70% ethanol, E.coli were killed in 10 seconds by all concentrations of ethanol from 40% to 100%.
- Iodines, phenolics,
- Glutaraldehyde, formaldehyde
- Electrolyzed oxidizing water at 23°C was effective in 10 minutes in producing a 5 log10 decrease in E. coli O157:H7inoculated onto kitchen cutting boards. Some findings indicate that Slightly Acidic Electrolyzed Water (pH 5.6, 23mg/l available chlorine concentration) with low available chlorine concentration can inactivate E. coli and therefore SAEW shows a high potential of application in agriculture and food industry as an environmentally friendly disinfection agent.
- A quaternary ammonium compound (within 30 sec).
2.8. Francisella tularensis (type A & B)
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Type A: more virulent strain (found in North America)
Type B: In Europe, the less virulent strain (subspecies holarctica)
Transmission: Contact of skin or mucous membranes with infectious materials, accidental parenteral inoculation, ingestion, and exposure to aerosols and infectious droplets.
Survival: Under natural conditions, F. tularensis may survive for extended periods in a cold, moist environment, 16 days– up to 12 weeks in dry matter. Some findings would expect a short half-life due to desiccation, solar radiation, oxidation and other environmental factors, and a very limited risk from secondary dispersal.
Infectious dose: 5 - 10 organisms by the respiratory route; 106 - 108 organisms by ingestion.
Inactivation: Gram-negative bacteria not spores forming.
Decontamination can be achieved by spraying the suspected contaminant with a:
-10% bleach solution (1 part household bleach and 9 parts water, 10 min contact time),
- followed by 70 % ethanol
Also glutaraldehyde and formaldehyde and VHP (vaporized hydrogen peroxide) fumigation are effective.
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Transmission: Inhalation of infectious droplets or airborne droplet nuclei.
Infectious dose: Unknown.
Survival: Gram-negative bacteria not spore forming.
- H. influenza does not survive long term in the environment (less than 1 day), it can survive more than 18 h in mucous and 12 h on plastic.
Inactivation: Phenolic disinfectants, 1% sodium hypochlorite, 70% ethanol, formaldehyde, glutaraldehyde, iodophore and peracedic acid.
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Transmission: Aerosol inhalation and aspiration of contaminated water, possible aerosol inhalation during animal challenge studies.
Survival:L. pneumophila was found to survive for up to 139 days in distilled water and 415 days in tap water. Can persist outside of the host in biofilms like those formed in potable and health care facility water systems > 98 days.
Legionella are able to survive under a wide range of water conditions, increase in summer (higher water temperatures) including temperatures from 0 to 63°C and a pH range of at least 5.0-8.5.
L. pneumophila is associated with biofilm (sessile bacteria) are more resistant to inactivation.
Infectious dose: Unknown, but considered low.
Inactivation: Gram-negative bacteria not spore forming.
susceptible to:
- 1% solutions of sodium hypochlorite,
- 2% phenol,
-2% gluteraldehyde, isopropyl alcohol, and formaldehyde.
2.11. Mycobacterium tuberculosis
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Transmission: Inhalation, aerosols, accidental parenteral inoculation, direct contact with mucous membranes, ingestion.
Survival: 1 day – 4 months on inanimate surfaces at laboratory conditions.
M. tuberculosis may survive in sputum:
- 42 days – 309 days on glass
- 1 day – more than 31 days on paper
- 30 – 123 days on sand
- 70 days on wood
- 14 – 135 days on paper
M. tuberculosis may survive in suspension 41 day on glass.
Infectious dose: Low, 10 bacteriathrough inhalation.
Inactivation: Gram-negative bacteria spore forming.
- Quaternary ammoniums inhibit tubercle bacilli but do not kill them. Resistant Mycobateria are known.
- M. tuberculosis is also resistant to acids and alkali.
-Mercurial compounds are considered to be ineffective against the Mycobacteria.
-3% phenolics and iodophors have been deleted as high-level disinfectants because of their unproven efficacy.
Efficient disinfectants are:
- 5% phenol, 5% formaldehyde, during at least ten minutes.
- 2% glutaraldehyde during 30 minutes exposure or 5% sodium hypochlorite during 1 minute.
- Ethyl and isopropyl alcohols in high concentrations are generally accepted to be excellent Mycobactericidal agents. 70% ethyl alcohol (ethanol) but less active on spores.
- 95% ethanol killed the tubercle bacilli in sputum or water suspension within 15 seconds.
- 70% isopropyl alcohol destroyed 104 M. tuberculosis in 5 minutes, whereas a simultaneous test with 3% phenolic required 2–3 hours to achieve the same level of microbial kill.
- Formaldehyde vapours can be used to disinfect Biosafety cabinet and facilities.
- Iodine and ionophores are strongly bactericide and are considered to be effective against Mycobacteria and are generally used in combination with ethyl alcohol.
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Transmission: Parenteral inoculation, exposure of mucous membranes to infectious droplet nuclei or aerosols, and ingestion.
Survival: N. meningitidis does not survive well outside of host. It has been reported to survive on glass and plastic at ambient temperatures for hours to 1 day.
Infectious dose: Unknown.
Inactivation: Gram-negative bacteria not spore forming.
N. meningitidisis is highly susceptible to common disinfectants:
- 1% sodium hypochlorite
- 70% ethanol,
- Phenolics,
- 2% glutaraldehyde, formaldehyde, and peracetic acid.
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Transmission: Ingestion, parenteral inoculation, importance of aerosol exposure not known.
Survival: Salmonella may survive in slurry for more than 77 days and grow in temperatures ranging from 6 to 47 °C.
In soil for 20 days; however, on dry inanimate surfaces in laboratory conditions Salmonella spp. are found to survive for 1 day.
Survival of S. typhimurium (not S. typhi in this study) was investigated during mesophilic anaerobic digestion of cattle dung. After an incubation period of 10 days at 37 °C, all S. typhimurium were inactivated.
Infectious dose: 105 organisms (compared to S. Typhimurium 109 organisms)
However, investigations of outbreaks of salmonellosis suggest that the infective dose was often low.
Inactivation: Gram-negative bacteria.
Most disinfectants were ineffective against Salmonella in a field situation.
Two very effective disinfectants on artificially contaminated and biofilm-covered surfaces are:
- Sodium hypochlorite [effective at a concentration of 0.05% (vol/vol)] and -alkaline peroxide compounds [1% (wt/vol)].
- Killed in 10 sec by all concentrations of ethanol from 40% to 100%.
Some findings indicate that Slightly Acidic Electrolyzed Water (pH 5.6, 23mg/l available chlorine concentration) with low available chlorine concentration can inactivate Salmonella spp. and therefore SAEW shows a high potential of application in agriculture and food industry as an environmentally friendly disinfection agent.
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Class of risk 3: Shigella dysenteriae (Type 1)
Transmission: Ingestion or accidental parenteral inoculation.
Survival: 2 days to 5 months on dry inanimate surfaces, up to 10 days in citric juices and carbonated soft drinks, several days on contaminated vegetables, over 3 hours on fingers, 2 to 28 days on metal utensils at 15°C or 0 – 13 days at 37°C, in faeces for 12 days at 25°C, and water for under 3 days. Growth is possible at 25°C – 37°C and bacteria can survive at 5°C on MacConkey agar. Flies can carry Shigellafor up to 20 – 24 days.
Infectious dose: Infection can result from ingestion of 10 – 200 organisms.
Inactivation: Gram-negative bacteria.
Susceptible to:
-1% sodium hypochlorite,
-70% ethanol,
-2% glutaraldehyde, formaldehyde,
- Iodines, phenolics.
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Transmission: Ingestion; parenteral inoculation; droplet and aerosol exposure of mucous membranes; contact exposure of broken skin.
Survival:Staphylococcus aureus including MRSA (Methicillin Resistant Staphylococcus aureus): 7 days – 7 months (no obvious difference in survival between multiresistant and susceptible strains on inanimate surfaces at laboratory conditions.
Infectious dose: Great variation exists according to strain.
Inactivation:
In general susceptible to many disinfectants:
- 1% sodium hypochlorite, 100 ppm of free chlorine killed 106–107 S. aureus, in <10 minutes,
- Iodine/alcohol solutions,
- Glutaraldehyde, formaldehyde etc.
- Hydrogen peroxide seemed less efficient.
- In vitro suspension tests showed that solutions containing about 140 ppm chlorine dioxide achieved a reduction factor exceeding 106 of S. aureus.
Some findings indicate that Slightly Acidic Electrolyzed Water (pH 5.6, 23mg/l available chlorine concentration) with low available chlorine concentration can inactivate S. aureus and therefore SAEW shows a high potential of application in agriculture and food industry as an environmentally friendly disinfection agent.
The US Environmental Protection Agency provides an extensive list of available commercial products that have been approved for the use of environmental disinfection of MRSA.
Legend:
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H: Human pathogen, A: Animal pathogen, n: Class of risk or Risk group
(*) Micro-organisms of risk group 3 that may present a limited risk of infection for humans and animals because they are not normally infectious by the airborne route.
3. Data on the persistence and the susceptibility to disinfectants of some parasites
Cryptosporydium spp., Echinococcus spp., Leishmania spp., Naegleria fowleri, Toxoplasma gondii
The data provided (when available in the litterature) for each pathogenic organisms listed below are the following: Transmission, persistence, infectious dose, inactivation
3.1. Cryptosporydium spp., Cryptosporidium parvum, C. hominis (protozoa)
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Transmission: Ingestion (faecal-oral route, food and water-borne transmission), airborne transmission: lethal respiratory cryptosporidiosis has been reported in immune compromised persons.
Laboratory exposure: Ingestion, accidental parenteral inoculation, airborne transmission.
Infectious dose: ID50=132 oocysts, in another study, ID50 value ranged from 9 to 1024 oocysts.
Survival: Environmentally resistant oocysts can remain infective under cool, moist conditions for many months: at 0-20°C for 6 months in deionised water, at 25-30°C for 3 months and at 35°C for 1 week. Oocysts remained viable for over 35 days at 4°C in marine water held in dark, for 40 days at 18°C under 35% salinity.
Oocysts are killed immediately at -70°C even in the presence of a variety of cryoprotectants. At higher T° oocysts survive longer, up to 8h at -20°C but not 24 h, 1 week at -10°C, 2 months at -5°C.
Freezing and thawing at more than 72°C for 1 min or 55°C for 15-20 min have effectively inactivated oocysts. 4h of dessication at room temperature is lethal to oocysts. In human feces: 6 months at 4°C, 78% oocysts died.
Inactivation: highly resistant to most disinfectants (6% sodium hypochlorite, 70% ethanol, 70% isopropanol, 37% methanol).
The most effective are the three gaze’s ammonia, ethylene oxide and methyl bromide.
Ozone: inactivation is achievable with an exposure of 1ppm for 5 min; 2.19 log10 units inactivation with 2 mg/L for 10 min. Oocysts partly resistant to concentration used in water treatment.
U.V.: U.V. inactivation: 3.75 log10 Unit’s inactivation with 500mJ/cm.
Chlorine dioxide: oocysts partly resistant to concentrations used in water treatment. 6% hydrogen peroxide for 13 or 33 min.
Ammonia: large contact time required for oocyst inactivation, 5.8M ammonia for 1 day. In another study, 0.05M ammonia inactivated more than 75% of oocysts after 24h exposure.
Neopredisan© >1% (25% chlorocresole) for 2 h.
Contaminated skin should be thoroughly washed; no disinfectant effective against Cryptosporidium is safe for use on skin. Contaminated clothing and equipment should be autoclaved.
3.2. Echinoccocus spp., Echinococcus multilocularis, E. granulosus (Cestode, Taenidae)
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H
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A
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3*
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3
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Transmission: Ingestion of eggs by hands contaminated from the feces of infected animals (foxes, dogs) or from soil while gardening, eating contaminated uncooked food from fields or gardens; drinking contaminated spring water; or inhaling dust containing tapeworm eggs.
Laboratory exposure: droplet exposure of mucous membranes, ingestion
Infectious dose: Unknown.
Survival: Eggs can survive in the environment several months at 4-15°C in an atmosphere containing 85-95% relative humidity.
E. multilocularis: 1 year at 4-15°C (85-95% relative humidity), 8 months during the winter (between -18°C and 4°C), and 78 days during the summer (≤43°C)
E. granulosus: 225 days at 6°C, 3 weeks at 30°C.
Inactivation: Infective material can be decontaminated by freezing at -80°C for 4 days, by heating to 70°C for 12h, by autoclave.
- Sodium hypochlorite 10%.
3.3. Leishmania spp., L. donovani, L. major, L. Mexicana, L. braziliensis (Protozoa)
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H
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A
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2 & 3*
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3
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Transmission: Vector, in nature by the bite of infected female sand fly.
Laboratory transmission:
- Parenteral inoculation (percutaneous exposure via a contaminated sharp), animal bites, c ontact of non-intact skin or aerosol transmission though mucous membranes with cultured parasites or specimens from infected persons or animals. Infective stages may be present in blood, faeces, and lesion exudates. Ingestion.
Infectious dose: During natural transmission: unknown, 103 promastigotes per biting fly, low (600 –>1000 promastigotes), even a small inoculum can cause illness.
Severe pathologies might be the result of a very high-dose inoculum, whereas subclinical infections, which account for a high proportion of Leishmania exposures in humans, might be the result of infected flies delivering a number of parasites below the threshold required to produce overt histopathological changes in the host.
Survival: does not survive outside host or culture, but remains viable for 35 days in whole blood kept at 4°C.
Inactivation of bloodstream forms of L. major: 5 min exposure to 0.2% TriGene, 0.1% liquid hand soap, 0.05% bleach (0.05% NaOCl), 5 min exposure to 80-90% ethanol, 5 min exposure to 15-17.5% water, 5 min at 50°C.
3.4. Naegleria fowleri (Free-living amebae)
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H
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A
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3
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Transmission: By swimming in warm fresh water, not found in salt water, the parasite invades the central nervous system through the nasal mucosae and the cibriform plate.
Laboratory exposure:
- Inhalation of infectious aerosols or droplets or though exposures to mucous membranes, parenteral inoculation and contact of non intact skin.
Infectious dose: Unknown.
Survival: Thermophilic, can tolerate T° >45°C, sensitive to some environmental conditions such as drying, pH extremes and cannot survive in sea water.
Inactivation: Chlorine inactivation (1mg/ml), ultraviolet (UV) light disinfection. Enhanced inactivation of N. fowleri by a combined system of free chlorine (1mg/ml) and copper and silver.
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H
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A
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2
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3
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Transmission: Ingestion of food or water contaminated with oocysts from cat feces or the ingestion of undercooked tissues cysts (bradyzoïtes).
Infectious dose: One live oocyst is orally infective to mice and pigs whereas 100 or more oocysts may be required to establish infection in a cat. Unknown for humans.
Survival: Sporulated oocysts survive for long periods under moderate environmental conditions. They can survive in moist soil for months to years; they survive on fruits and vegetables for long periods.
Inactivation: Sulfuric acid 63% / dichromate 7% for 24h, ethanol 95% / acetic acid 5% for 24h, ammonium hydroxide 5% for 30 min, ammonia liquid 5.5% (undiluted household ammonia 5.5%) for 3h, tinture of Iodine 2% for 3h, Drying at relative humidity 19% for 11 days, Lomasept for 3h.
Tissue cysts (bradyzoïtes) remain infectious in refrigerated carcasses (1°C to 6°C) or minced meat for up to 3 weeks. Cysts remain viable for > 11 days at -7°C. Tissue cysts are killed immediately by heating to 67°C. Solutions containing 2% sodium chloride or 1.4% potassium, or sodium lactate are effective within 8 hours of injection for the killing of T. gondii tissue cysts in pork loin.
Legend:
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H
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A
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n
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n
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H: Human pathogen, A: Animal pathogen, n: Class of risk or Risk group
(*) Micro-organisms of risk group 3 that may present a limited risk of infection for humans and animals because they are not normally infectious by the airborne route.