Information F. Daschner, I. Borneff, G. G. Jackson, M. T. Parker
Detection, Prevention and Control of Hospital-Acquired Infections* I. Proven and Unproven Methods in Hospital Infection Control" Summary of an International Workshop On 24---25 September 1977 an international workshop on proven and unproven methods in hospital infection control was organized in Baiersbronn, Germany, by the Department of Hospital Epidemiology, Freiburg. Twenty-two international experts from eight ctifferent countries were invited to say how they thought hospital cross-infection laboratories should function, and what the proven standards in hospital infection control should be. The following conclusions have been drawn by the chairmen of the workshop. Preamble Nosocomial infections are a major worldwide problem especially in hospitals providing acute medical care. The acquisition of such infection by four to eight per cent of patients, which characterises most general hospitals, indicates that this is an endemic disease of major proportions. It is estimated that more than one-tenth of all hospital bed-days are used for patient care related to hospital acquired infections. The problem has received some attention, but deserves further study in order to determine the common sources of infection and routes of transmission, and to find the best methods for the early recognition and prevention of hospital-acquired microbial disease. Occurrence of the disease is the essential index of nosocomial infections; however, detailed studies of the colonisation of patients and staff by pathogenic microorganisms can be used to assist in demonstrating the true prevalence and the more important conditions of transmission. Both hospital personnel and patients run an increased risk of acquiring nosocomial pathogenic micro-organisms. Urinary tract infections, wound infections, and respiratory tract infections are responsible for approximately three-quarters of the episodes of this disease. The prevalence of each of these and other severe infections such as bacteremia can be augmented or reduced by identifiable procedures and practices. It is estimated that one-quarter to one-third of such nosocomial infections are preventable. Clinical Aspects Hospital-acquired infections are diverse in their clinical manifestations and microbiological causes; they are determined mainly by medications and procedures to which patients are subjected, by the nature of host diseases and by some general and specific conditions that promote susceptibility to infection. The infecting micro-organisms may be derived either from the patient's own flora or from extraneous sources. An effective programme for the prevention of infection is thus a complex mixture of measures directed against the major expected risks to each individual class of patient; these should be kept to a minimum for economic and practical reasons. The assessment of the efficacy of an individual preventive measure by controlled * See also the report on this workshop in I N F E C T I O N No. 1/1978.
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clinical trial is very difficult, but efforts should be made to do this whenever the particular measure is either expensive or time-consuming. Nevertheless, many measures have to be applied on the basis of a reasonable inference that they will prevent infection, and this inference may of necessity come from imperfect and fragmentary experimental studies supported by general microbiological knowledge. Purely microbiological evidence is often useful in eliminating obviously ineffective or relatively unimportant measures. Some examples of proven and unproven methods in hospital infection control are given in Table 1. A unit responsible for infection control should be established in each hospital and should include a prominent medically qualified staff member (if not the head of the hospital) who is interested in the problem, and delegates authority for taking decisions relating to nosocomial infections. He should have as staff one or more professional hospital hygienists (epidemiologists), infection-control nurse(s) with training and experience in patient care, ward procedures, Table1: Examples of proven and unproven methods in Hospital Infection Control. PROVEN
UNPROVEN
Sterilization Hand washing / disinfection Disinfection of respiratory and inhalation therapy equipment Isolation procedures Closed urinary drainage systems Careful nursing techniques (urinary catheter, tracheostoma, intravenous catheters, etc.) No-touch dressing technique Perioperative antibiotic prophylaxis in certain clean-contaminated and contaminated operative procedures
Disinfection of floors, walls and sinks UV-lights Laminar air flow systems Disinfection mats Plastic shoe covers Antibiotic prophylaxis in clean operative procedures
Prof. Dr. F. Daschner, Klinikhygiene des Universitiitsklinikums Freiburg, Hugstetter Str. 55, D-7800 Freiburg, West Germany; Prof. Dr. J. Borneff, Hygieneinstitut der Universitiit Mainz, Hochhaus am Augustusplatz, D-6500 Mainz, West Germany; Prof. G. G. Jackson, Abraham I,incoln School of Medicine, Chicago, Illinois, USA; Dr. M. T. Parker, Public Health Laboratory Service, Colindale Avenue, London, United Kingdom.
administrative capability, diplomacy and a strong personality. Laboratory support must be available for specific microbiological determinations. A n essential part of the responsibility of the infection-control committee is to establish in the staff an awareness of the problem of hospital-acquired infections, and constantly to organize training programmes suitable for all grades of personnel, on the correct performance of preventive measures.
Bacteriological Aspects The prevention of endogenous infection of the patient with micro-organisms from his own body flora depends upon good surgical practice, the use of "no-touch" techniques for alI procedures in which the skin is breached, efficient preoperative skin preparation, and (in certain carefully selected patients, see below) the use of prophylactic chemotherapy.
Extraneous infection may be by the aerial or the contact route. The former route is of importance in particular circumstances, such as the infection of open wounds in the operating theatre or of extensive burns in wards. Here, the provision of adequate artificial ventilation with clean air is an important preventive measure. In most other situations, however, the contact route is pre-eminent, and infection is transmitted by the hands of members of the staff or by contaminated objects or substances. Although minimal standards of hospital construction and design are important, the greatest emphasis should be placed upon the provision of adequate staff, and their training and motivation to perform specific procedures in the correct manner at all times. Hand-washing is the most important single measure for the control of contact infection. The anti-bacterial action of hand-washing materials is of less importance than the dilution effect of running water and detergent. When the required frequency of hand-washing introduces practical limitations on the daily work on the staff, or where contamination is gross, disposable gloves should be used. Other contaminated objects and substances that are important sources of contact infection are those that are likely to be brought into direct contact with susceptible sites on the patient. General ward surfaces, such as floors, walls and ceilings, do not fall into this category. It is usually sufficient to maintain good "domestic" standards of cleanliness of these; chemical disinfection will be required only for areas that have been visually contaminated with body secretions. Widespread programmes of "general" disinfection of hospital surfaces produce only a transient effect, and tend to divert large sums of money from other more worthy objectives; they may also, lead to adverse hygienic effects, if an inappropriate agent is used. On the other hand, every effort should be made to provide reliable means of sterilisation and disinfection of equipment and materials that come into more intimate contact with patients. The provision of facilities for the isolation of patients is probably the next most important objective in the control of infection, but the requirements vary according to the type of patient to be accommodated. Thus, different facilities are required for the protection of highly susceptible patients (protective isolation) and for the containment of infectious persons (source isolation). However, not all source isolation need be comprehensive, and for certain classes of patients all that needs to be provided is a single room with separate toilet facilities but without artificial ventilation. T h e nursing of patients in isolation is labour-intensive, and the provision of elaborate isolation facilities without adequate staffing is selfdefeating.
SteriIisation and Disinfection Clear decisions must be made as to which objects require sterilisation and which only need to be disinfected (i. e., so treated that vegetative bacteria and viruses, but not necessarily bacterial spores, are destroyed). In general, all objects brought into contact with body tissues must be sterilised, but it may be sufficient to disinfect objects that come into contact only with mucous membranes. In hospitals, an appropriate heating process should, whenever possible, be used either for sterilisation or for disinfection, although other types of sterilisation process may be acceptable when applied under well-controlled industrial conditions. In any event, "cold" chemical sterilisation should be avoided as far as possible in hospitals, and disinfection by chemical means - - when unavoidable - - needs very careful monitoring. Monitoring of the general environment is of limited value unless directed to the investigation of specific outbreaks or used as a purely educational measure. Much hospital equipment, particularly apparatus of a complex nature, is difficult and occasionally impossible to sterilise or even disinfect. Manufacturers of such equipment are strongly urged to modify design so that it can be used without risk of subsequent infection.
Antibiotics and Antibiotic Policy Antibiotic use for appropriate chemotherapy or chemoprophylaxis reduces morbidity, lethality, and the in-hospital cost of individual episodes of infection whether naturally or nosocomiallw acquired. Approximately one-third of patients admitted to hospitals receive antimicrobial drugs. Although this level of use is accepted in practice, in some respects it is excessive, if not in the n u m b e r of patients treated, in the number of drugs used and the duration of administration. Such antibiotic use causes coincidental changes in the flora of individual patients and in the hospital locale. These changes have an important influence on the prevalence and character of nosocomial infections. The frequency of emergence of antibiotic-resistant organisms within a hospital or ward varies from place to place and is proportional to the amount of use of the specific antimicrobial drugs tested. This is especially true if the drugs are used topically on a heavily contaminated tissue or given orally in the case of non-absorbable drugs that reach the lower bowel. Chemoprophylaxis in surgical procedures that are categorised as clean but will be contaminated by the nature of the surgical procedure, and those that are infected or contaminated beforehand can reduce the frequency of infections. There is no reduction of infection in clean operations. The duration of prophylaxis beyond the peri-operative period is not proved to be of any benefit, and longer duration of prophylaxis can have an adverse effect on the occurrence of nosocomial infections. Some prophylactic uses of antimicrobial drugs for conditions .in which they are not proved to be effective can be justified owing to the high lethality of any infection if one were to occur in such patients. The insertion of prosthetic joints or heart valves are considered such indications, but the use of prophylaxis must be brief. Antimicrobial prophylaxis given to hospital patients with non-surgical conditions is of doubtful benefit unless there is an acute condition that can be quickly corrected. The longer the duration of prophylaxis, the greater the likelihood of nosocomial infection with resistant bacteria. A requirement for the physician to declare the indication for each antibiotic prescription within general categories such as 'prophylaxis', 'infection suspected', or 'infection present' is helpful in setting standards of use; it also permits self and staff evaluation of antibiotic practices in a hospital,
Infection 6 (1978) Nr. 4
195
ward or service and its influence on nosocomial infections. One function of the infection control committee is to create an awareness of the patterns of antibiotic use and the level of specific antibiotic-resistant bacterial species in relation to the occurrence of nosocomial infections. Such information is useful in the education and persuasion of hospital physicians with regard to a locat antibiotic use policy. Restrictions on the use of certain antibiotics may be recommended in some hospitals. By themselves such restrictions have little effect on the prevalence of nosocomial infections. The purpose is to minimise the problem of antibiotic resistance and favourably influence the outcome of those infections that occur.
Economic Aspects Economic aspects of hospital infections have only been considered in the last few years. The main problem appears to be the establishment of a practicable methodology to
196
Infection 6 (1978) Nr. 4
study the various facets involved. The organisation and evaluation of any control of infection programme would inevitably have to include some cost-efficiency and cost-effectiveness studies. The average cost for prevention and control of infection in hospitals varies widely, hnd national studies are strongly recommended. Instead of employing monetary terms, cost-effectiveness is often used and is meant to express the results achieved in the n u m b e r of cases of prevented hospital infection by early detection of first case and application of control measures. Cost-efficiency, on the other hand, expresses the ability of a specific activity, competent laboratory services, for example, to be effective in reducing hospital infection rates within the context of the available resources. It is proposed that information be gathered on the presently available data, and the possibility of adaptation of these data according to the various national, regional and local situations be investigated Guidelines for conducting cost-benefit studies should be developed by the responsible authorities in colloboration with managerial expertise.
Detection, Prevention and Control of Hospital-Acquired Infections* I. Proven and Unproven Methods in Hospital Infection Control" Summary of an International Workshop On 24---25 September 1977 an international workshop on proven and unproven methods in hospital infection control was organized in Baiersbronn, Germany, by the Department of Hospital Epidemiology, Freiburg. Twenty-two international experts from eight ctifferent countries were invited to say how they thought hospital cross-infection laboratories should function, and what the proven standards in hospital infection control should be. The following conclusions have been drawn by the chairmen of the workshop. Preamble Nosocomial infections are a major worldwide problem especially in hospitals providing acute medical care. The acquisition of such infection by four to eight per cent of patients, which characterises most general hospitals, indicates that this is an endemic disease of major proportions. It is estimated that more than one-tenth of all hospital bed-days are used for patient care related to hospital acquired infections. The problem has received some attention, but deserves further study in order to determine the common sources of infection and routes of transmission, and to find the best methods for the early recognition and prevention of hospital-acquired microbial disease. Occurrence of the disease is the essential index of nosocomial infections; however, detailed studies of the colonisation of patients and staff by pathogenic microorganisms can be used to assist in demonstrating the true prevalence and the more important conditions of transmission. Both hospital personnel and patients run an increased risk of acquiring nosocomial pathogenic micro-organisms. Urinary tract infections, wound infections, and respiratory tract infections are responsible for approximately three-quarters of the episodes of this disease. The prevalence of each of these and other severe infections such as bacteremia can be augmented or reduced by identifiable procedures and practices. It is estimated that one-quarter to one-third of such nosocomial infections are preventable. Clinical Aspects Hospital-acquired infections are diverse in their clinical manifestations and microbiological causes; they are determined mainly by medications and procedures to which patients are subjected, by the nature of host diseases and by some general and specific conditions that promote susceptibility to infection. The infecting micro-organisms may be derived either from the patient's own flora or from extraneous sources. An effective programme for the prevention of infection is thus a complex mixture of measures directed against the major expected risks to each individual class of patient; these should be kept to a minimum for economic and practical reasons. The assessment of the efficacy of an individual preventive measure by controlled * See also the report on this workshop in I N F E C T I O N No. 1/1978.
194
Infection 6 (1978) Nr. 4
clinical trial is very difficult, but efforts should be made to do this whenever the particular measure is either expensive or time-consuming. Nevertheless, many measures have to be applied on the basis of a reasonable inference that they will prevent infection, and this inference may of necessity come from imperfect and fragmentary experimental studies supported by general microbiological knowledge. Purely microbiological evidence is often useful in eliminating obviously ineffective or relatively unimportant measures. Some examples of proven and unproven methods in hospital infection control are given in Table 1. A unit responsible for infection control should be established in each hospital and should include a prominent medically qualified staff member (if not the head of the hospital) who is interested in the problem, and delegates authority for taking decisions relating to nosocomial infections. He should have as staff one or more professional hospital hygienists (epidemiologists), infection-control nurse(s) with training and experience in patient care, ward procedures, Table1: Examples of proven and unproven methods in Hospital Infection Control. PROVEN
UNPROVEN
Sterilization Hand washing / disinfection Disinfection of respiratory and inhalation therapy equipment Isolation procedures Closed urinary drainage systems Careful nursing techniques (urinary catheter, tracheostoma, intravenous catheters, etc.) No-touch dressing technique Perioperative antibiotic prophylaxis in certain clean-contaminated and contaminated operative procedures
Disinfection of floors, walls and sinks UV-lights Laminar air flow systems Disinfection mats Plastic shoe covers Antibiotic prophylaxis in clean operative procedures
Prof. Dr. F. Daschner, Klinikhygiene des Universitiitsklinikums Freiburg, Hugstetter Str. 55, D-7800 Freiburg, West Germany; Prof. Dr. J. Borneff, Hygieneinstitut der Universitiit Mainz, Hochhaus am Augustusplatz, D-6500 Mainz, West Germany; Prof. G. G. Jackson, Abraham I,incoln School of Medicine, Chicago, Illinois, USA; Dr. M. T. Parker, Public Health Laboratory Service, Colindale Avenue, London, United Kingdom.
administrative capability, diplomacy and a strong personality. Laboratory support must be available for specific microbiological determinations. A n essential part of the responsibility of the infection-control committee is to establish in the staff an awareness of the problem of hospital-acquired infections, and constantly to organize training programmes suitable for all grades of personnel, on the correct performance of preventive measures.
Bacteriological Aspects The prevention of endogenous infection of the patient with micro-organisms from his own body flora depends upon good surgical practice, the use of "no-touch" techniques for alI procedures in which the skin is breached, efficient preoperative skin preparation, and (in certain carefully selected patients, see below) the use of prophylactic chemotherapy.
Extraneous infection may be by the aerial or the contact route. The former route is of importance in particular circumstances, such as the infection of open wounds in the operating theatre or of extensive burns in wards. Here, the provision of adequate artificial ventilation with clean air is an important preventive measure. In most other situations, however, the contact route is pre-eminent, and infection is transmitted by the hands of members of the staff or by contaminated objects or substances. Although minimal standards of hospital construction and design are important, the greatest emphasis should be placed upon the provision of adequate staff, and their training and motivation to perform specific procedures in the correct manner at all times. Hand-washing is the most important single measure for the control of contact infection. The anti-bacterial action of hand-washing materials is of less importance than the dilution effect of running water and detergent. When the required frequency of hand-washing introduces practical limitations on the daily work on the staff, or where contamination is gross, disposable gloves should be used. Other contaminated objects and substances that are important sources of contact infection are those that are likely to be brought into direct contact with susceptible sites on the patient. General ward surfaces, such as floors, walls and ceilings, do not fall into this category. It is usually sufficient to maintain good "domestic" standards of cleanliness of these; chemical disinfection will be required only for areas that have been visually contaminated with body secretions. Widespread programmes of "general" disinfection of hospital surfaces produce only a transient effect, and tend to divert large sums of money from other more worthy objectives; they may also, lead to adverse hygienic effects, if an inappropriate agent is used. On the other hand, every effort should be made to provide reliable means of sterilisation and disinfection of equipment and materials that come into more intimate contact with patients. The provision of facilities for the isolation of patients is probably the next most important objective in the control of infection, but the requirements vary according to the type of patient to be accommodated. Thus, different facilities are required for the protection of highly susceptible patients (protective isolation) and for the containment of infectious persons (source isolation). However, not all source isolation need be comprehensive, and for certain classes of patients all that needs to be provided is a single room with separate toilet facilities but without artificial ventilation. T h e nursing of patients in isolation is labour-intensive, and the provision of elaborate isolation facilities without adequate staffing is selfdefeating.
SteriIisation and Disinfection Clear decisions must be made as to which objects require sterilisation and which only need to be disinfected (i. e., so treated that vegetative bacteria and viruses, but not necessarily bacterial spores, are destroyed). In general, all objects brought into contact with body tissues must be sterilised, but it may be sufficient to disinfect objects that come into contact only with mucous membranes. In hospitals, an appropriate heating process should, whenever possible, be used either for sterilisation or for disinfection, although other types of sterilisation process may be acceptable when applied under well-controlled industrial conditions. In any event, "cold" chemical sterilisation should be avoided as far as possible in hospitals, and disinfection by chemical means - - when unavoidable - - needs very careful monitoring. Monitoring of the general environment is of limited value unless directed to the investigation of specific outbreaks or used as a purely educational measure. Much hospital equipment, particularly apparatus of a complex nature, is difficult and occasionally impossible to sterilise or even disinfect. Manufacturers of such equipment are strongly urged to modify design so that it can be used without risk of subsequent infection.
Antibiotics and Antibiotic Policy Antibiotic use for appropriate chemotherapy or chemoprophylaxis reduces morbidity, lethality, and the in-hospital cost of individual episodes of infection whether naturally or nosocomiallw acquired. Approximately one-third of patients admitted to hospitals receive antimicrobial drugs. Although this level of use is accepted in practice, in some respects it is excessive, if not in the n u m b e r of patients treated, in the number of drugs used and the duration of administration. Such antibiotic use causes coincidental changes in the flora of individual patients and in the hospital locale. These changes have an important influence on the prevalence and character of nosocomial infections. The frequency of emergence of antibiotic-resistant organisms within a hospital or ward varies from place to place and is proportional to the amount of use of the specific antimicrobial drugs tested. This is especially true if the drugs are used topically on a heavily contaminated tissue or given orally in the case of non-absorbable drugs that reach the lower bowel. Chemoprophylaxis in surgical procedures that are categorised as clean but will be contaminated by the nature of the surgical procedure, and those that are infected or contaminated beforehand can reduce the frequency of infections. There is no reduction of infection in clean operations. The duration of prophylaxis beyond the peri-operative period is not proved to be of any benefit, and longer duration of prophylaxis can have an adverse effect on the occurrence of nosocomial infections. Some prophylactic uses of antimicrobial drugs for conditions .in which they are not proved to be effective can be justified owing to the high lethality of any infection if one were to occur in such patients. The insertion of prosthetic joints or heart valves are considered such indications, but the use of prophylaxis must be brief. Antimicrobial prophylaxis given to hospital patients with non-surgical conditions is of doubtful benefit unless there is an acute condition that can be quickly corrected. The longer the duration of prophylaxis, the greater the likelihood of nosocomial infection with resistant bacteria. A requirement for the physician to declare the indication for each antibiotic prescription within general categories such as 'prophylaxis', 'infection suspected', or 'infection present' is helpful in setting standards of use; it also permits self and staff evaluation of antibiotic practices in a hospital,
Infection 6 (1978) Nr. 4
195
ward or service and its influence on nosocomial infections. One function of the infection control committee is to create an awareness of the patterns of antibiotic use and the level of specific antibiotic-resistant bacterial species in relation to the occurrence of nosocomial infections. Such information is useful in the education and persuasion of hospital physicians with regard to a locat antibiotic use policy. Restrictions on the use of certain antibiotics may be recommended in some hospitals. By themselves such restrictions have little effect on the prevalence of nosocomial infections. The purpose is to minimise the problem of antibiotic resistance and favourably influence the outcome of those infections that occur.
Economic Aspects Economic aspects of hospital infections have only been considered in the last few years. The main problem appears to be the establishment of a practicable methodology to
196
Infection 6 (1978) Nr. 4
study the various facets involved. The organisation and evaluation of any control of infection programme would inevitably have to include some cost-efficiency and cost-effectiveness studies. The average cost for prevention and control of infection in hospitals varies widely, hnd national studies are strongly recommended. Instead of employing monetary terms, cost-effectiveness is often used and is meant to express the results achieved in the n u m b e r of cases of prevented hospital infection by early detection of first case and application of control measures. Cost-efficiency, on the other hand, expresses the ability of a specific activity, competent laboratory services, for example, to be effective in reducing hospital infection rates within the context of the available resources. It is proposed that information be gathered on the presently available data, and the possibility of adaptation of these data according to the various national, regional and local situations be investigated Guidelines for conducting cost-benefit studies should be developed by the responsible authorities in colloboration with managerial expertise.
