Background
Within the global infection control community, there is an ongoing controversy about the appropriate treatment of inanimate surfaces in hospitals in order to prevent transmission of nosocomial pathogens within an institution. Based on a lack of epidemiological data that would provide evidence of a benefit for the patient from surface disinfection (e.g., from a significant reduction of nosocomial infection rates), some scientists postulate that cleaning of surfaces with non-antimicrobial detergents is generally sufficient
New guidelines on treatment of surfaces in hospitals take into account more parameters which are considered to be relevant for preventing the transmission of nosocomial pathogens, such as the type of ward or the expected frequency of hand contact with a surface
Methods
Search strategy
The literature was systematically reviewed in MedLine on the internet homepage of the National Library of Medicine without language restrictions. The search was done on 29 December 2005 and covered all years available in MedLine. The following search terms were applied: persistence, survival, surface, fomite, bacteria, virus, pathogen, transmission, and nosocomial. In addition, the citations in each study found during the main search were reviewed for potential relevance. Finally, standard textbooks on infection control, bacteriology and virology were examined for information.
Selecting studies
All reports with experimental evidence on the duration of persistence of a nosocomial pathogen on any type of inanimate surface were included. Information from textbooks was also included, even if the chapter itself did not contain experimental evidence. At least two of the investigators decided on the relevance of each report. Reports were not blinded to the investigators so that they knew the names of the authors of all studies.
Interpretation of studies
For a clinically relevant summary, all nosocomial pathogens were grouped according to their importance in causing hospital-acquired hand-transmitted infections
Results
Persistence of bacteria
Most gram-positive bacteria, such as
Persistence of clinically relevant bacteria on dry inanimate surfaces.
Type of bacterium
Duration of persistence (range)
Reference(s)
Acinetobacter spp.
3 days to 5 months
[18, 25, 28, 29, 87, 88]
3 – 5 days
[89, 90]
up to 6 days
[91]
5 months
[92–94]
≤ 30 hours
[14, 95]
15 days
[90]
7 days – 6 months
[90, 96]
1–8 days
[21]
1.5 hours – 16 months
[12, 16, 17, 22, 28, 52, 90, 97–99]
Enterococcus spp. including VRE and VSE
5 days – 4 months
[9, 26, 28, 100, 101]
12 days
[90]
≤ 90 minutes
[23]
Klebsiella spp.
2 hours to > 30 months
[12, 16, 28, 52, 90]
Listeria spp.
1 day – months
[15, 90, 102]
> 2 months
[13, 90]
1 day – 4 months
[30, 90]
1 – 3 days
[24, 27, 90]
1 – 2 days
[90]
6 hours – 16 months; on dry floor: 5 weeks
[12, 16, 28, 52, 99, 103, 104]
6 hours – 4 weeks
[90]
10 days – 4.2 years
[15, 90, 105]
Salmonella spp.
1 day
[52]
3 days – 2 months; on dry floor: 5 weeks
[12, 90]
Shigella spp.
2 days – 5 months
[90, 106, 107]
7 days – 7 months
[9, 10, 16, 52, 99, 108]
1 – 20 days
[90]
3 days – 6.5 months
[90]
1 – 7 days
[90, 109]
Overall, gram-negative bacteria have been described to persist longer than gram-positive bacteria
Low temperatures, e.g., 4°C or 6°C, also improved persistence of most types of bacteria, such
The type of test material does not reveal a consistent result. Although some investigators report that the type of material has no influence on the persistence
Other factors were rarely investigated and hence provide inconsistent results. Longer persistence has been described with higher inocula
Persistence of fungi
Persistence of clinically relevant fungi on dry inanimate surfaces.
Type of fungus
Duration of persistence (range)
Reference(s)
1 – 120 days
[31, 53, 99, 110]
14 days
[110]
102 – 150 days
[31]
The presence of serum or albumin, a low temperature, and high humidity have been described as leading to longer persistence
Persistence of viruses
Most viruses from the respiratory tract such as
The influence of humidity on persistence has been described inconsistently. For entero-
For most viruses, such as
Inconsistent results are also reported for the influence of type of material. Some authors described that the type of material did not affect the persistence of
Other parameters for a longer persistence of viruses include the presence of fecal suspension
Persistence of other nosocomial pathogens
Cryptosporidium species have been reported to survive on dry surfaces for only 2 hours
Discussion
The most relevant nosocomial pathogens can persist on dry inanimate surfaces for months. In addition to the duration of persistence, some studies have also identified factors influencing persistence. A low temperature, such as 4°C or 6°C, was associated with longer persistence for most bacteria, fungi and viruses. High humidity (e.g., > 70%) was also associated with longer persistence for most bacteria, fungi, and viruses, although for some viruses conflicting results were reported. A few studies also suggest that a higher inoculum is associated with longer persistence. The type of surface material and the type of suspension medium, however, reveal inconsistent data. Overall, a high inoculum of the nosocomial pathogen in a cold room with high relative humidity will have the best chance for long persistence.
In most reports with experimental evidence, persistence was studied on dry surfaces using artificial contamination of a standardized type of surface in a laboratory. In most studies, bacteria were prepared in broth, water or saline. Viruses were usually prepared in a cell culture medium
In hospitals, surfaces with hand contact are often contaminated with nosocomial pathogens
Common modes of transmission from inanimate surfaces to susceptible patients
Common modes of transmission from inanimate surfaces to susceptible patients.
The main route of transmission is via the transiently contaminated hands of the healthcare worker
During outbreaks, the environment may play a significant role for transmission of nosocomial pathogens, as suggested by observational evidence. This has been described for various types of microorganisms, such as
The role of surface disinfection for the control of nosocomial pathogens has been a contentious issue for some time
Conclusion
Most nosocomial pathogens can persist on inanimate surfaces for weeks or even months. Our review supports current guidelines which recommend a disinfection of surfaces in specific patient-care areas in order to reduce the risk of transmission of nosocomial pathogens from inanimate surfaces to susceptible patients.
Competing interests
GK is a paid employee of Bode Chemie GmbH & Co. KG, Hamburg, Germany.
Authors' contributions
All authors contributed to the conception, review of studies, and analysis of data. All authors were involved in drafting and revising the manuscript. All authors approved the final version of the manuscript.
Persistence of clinically relevant viruses on dry inanimate surfaces.
Type of virus
Duration of persistence (range)
Source
Adenovirus
7 days – 3 months
[32, 34, 38–41, 111]
Astrovirus
7 – 90 days
[38]
Coronavirus
3 hours
[112, 113]
SARS associated virus
72 – 96 hours
[114]
Coxsackie virus
> 2 weeks
[34, 111]
Cytomegalovirus
8 hours
[115]
Echovirus
7 days
[39]
HAV
2 hours – 60 days
[35, 38, 41]
HBV
> 1 week
[116]
HIV
> 7 days
[117–119]
Herpes simplex virus, type 1 and 2
4.5 hours – 8 weeks
[34, 111, 118, 120]
Influenza virus
1 – 2 days
[39, 43, 121, 122]
Norovirus and feline calici virus (FCV)
8 hours – 7 days
[42, 45]
Papillomavirus 16
> 7 days
[123]
Papovavirus
8 days
[118]
Parvovirus
> 1 year
[118]
Poliovirus type 1
4 hours – < 8 days
[35, 118]
Poliovirus type 2
1 day – 8 weeks
[34, 38, 111]
Pseudorabies virus
≥ 7 days
[124]
Respiratory syncytial virus
up to 6 hours
[44]
Rhinovirus
2 hours – 7 days
[33, 125]
Rotavirus
6 – 60 days
[36 – 38, 41]
Vacciniavirus
3 weeks – > 20 weeks
[34, 126]