the efforts made to comprehend the essence of disease and its causes have shaped the history of medicine . even today we are unable to grasp why a particular person suffers from this or that affliction , and despite the advances made in deciphering the genetic code  which in any case explains only how the basic mechanism works , not why  the only recourse left seems to be to place our faith in a higher power . here we can discern a cause and effect chain , which in particular offers the practicable perspectives of prophylaxis and treatment . up till the time that robert koch discovered more than a hundred years ago that anthrax was caused by a bacterium , raging epidemics were seen as an expression of god s curse . while it was possible to control plague and cholera , in addition to new epidemics such as hiv / aids and sars long - forgotten scourges like but such spectacular pathogens account for only part of our problems ; the advances made in clinical medicine mean that today not only are we seeing patients with compromised immune systems , who in earlier times would have long succumbed to their underlying disease , but    that now such forms of immunosuppression induced , for instance , as a result of major surgery and organ transplants have become a serious problem in intensive care units . this means that it is not only the classic pathogens that are in the spotlight but also a plethora of ubiquitous microorganisms , which as saprophytes have hitherto elicited little attention but are found on all surfaces in a hospital and on the hands of staff . bereft of these insights , ignaz phillip semmelweis made the ingenious observation in vienna during the 19th century that primitive hand disinfection was able to reduce considerably the incidence of fatal puerperal fever . today many of these epidemics and infections have been brought under control , but in intensive care medicine sepsis continues to be the chief nemesis and while we can not exactly define the situation , an infection is implicated in the case of the vast majority of patients who die here , or has indeed been the cause of death .   and here we come upon a fortuitous confluence of all the factors that facilitate microbial invasion of the human body . the body s natural barriers have been breached through medical interventions , with the common integument sporting myriad large - lumened indwelling catheters , waldeyer s tonsilar ring breached by plastic tubes and probes , and even the longer male urethral tract is fitted with a catheter all the more to facilitate retrograde passage of bacteria .   on the other hand , immunocompromising therapeutic agents such as cytostacis and glucocorticoids , which in addition to the inability to ingest nutrition in a natural and efficient manner ensure that invading microorganisms will be able to multiply . drugs administered as stress ulcus prophylaxis give rise to a shift in the bacterial flora of the throat , thus laying the foundation for a lower respiratory tract infection .   with regard to bacterial resistance , antibiotic therapy , especially when used as prophylaxis , results in the bacteria becoming less sensitive to the drugs , while reinforcing selective pressures . disinfectants can be deployed not only against all potential microbial reservoirs outside the body , but also on the skin and mucous membranes . in the inanimate environment they can be used with essentially more potent effects than antibiotics , whose use must be governed by considerations of not unduly taxing the body . the hands of personnel as well as the therapeutic devices ranging from the respirator to the catheter are the chief sources of infection in intensive care units . if one disregards the endogenous gut flora and their antibiotic - induced alteration , we can target all microbes giving rise to nosocomial infections with disinfectants before their inoculation . disinfection is the cornerstone of any well - organized and hence effective infection control policy . only recently has a european study reported on the impressive reduction in the incidence of infections brought about by iodine - based products on the skin or at vascular access points as well as by antiseptic hand disinfection . an international study , which was launched in the usa , underlined the importance of oral decontamination in ventilation pneumonia , which is a key player among the nosocomial infections . disinfection , antibiotic therapy and possibly extracorporeal elimination methods can be contemplated for direct prevention of the establishment and multiplication of microorganisms . the latter are still in the incipient stages , while antibiotic treatment represents a double - edged sword since it acts selectively and the entire organism has to be taken into consideration . only disinfectants are able to unleash their full destructive might against microbes , especially when used on treatment devices that are not amenable to sterilization , but subsequent removal and , possibly , ensuring hand protection , can be a problem . discussions postulate the merits of using quaternary ammonium vs alcohol - based solutions , but what is decisive is optimal use to assure effective infection control tailored to the respective site of use . an objective evaluation of the suitability of such measures against the background of high costs is possible only through documentation of the clinical effects . already before the large outcome studies conducted during the past 20 years in the field of intensive care medicine attempts were made to analyze infection control on a large scale in central europe . while it is not easy to furnish proof of a direct link between efficient control and prevention methods and the incidence of infection , there is by now a consensus on the role of hand hygiene and of disinfection of the human body and of surfaces . but an international study that would be conducted only a decade later was not able to gain any further insights and could only emphatically advocate that european standards be introduced .   however , this study spanning 14 countries and more than 1000 intensive care units cast light on the importance of antiseptics . for disinfection of puncture sites before insertion of vascular catheters mainly alcoholic solutions were used ; the solution used for the urethral opening was not specified , and most disappointing aspect of this comprehensive survey was the fact that hand hygiene was assigned only a peripheral role .   in an age when medicine , in particular intensive care medicine , is risking becoming impaled on its own sword , with nosocomial infections being seen as one of the most critical aspects of high tech medicine , disinfection can serve as a bulwark against rising infection rates . emeritus assistant clinical director of the clinic for anaesthetics and general intensive medicine , vienna , austria . clinical investigator and legally sworn expert . he received a doctor s degree in 1963 and started a specialist training which he finished in 1969 as a specialist for anaesthetics . later he moved as austrian un - soldier to cyprus , afterwards to the albert einstein college of medicine , new york . in 1979 but he did not stay there : he became head of anaesthetics and intensive care department of the children hospital modid in tehran , iran . after his return he is named assistant medical director of the ahk vienna and finally assistant board director for the clinic for anaesthetics and general intensive care medicine vienna . he engages himself to a high degree in different ethics committees ( vice director of the inter - faculty institute for ethics in medicine , vice director of the ethics committee of the vienna medical faculty , chairman of the ethics committee and board - member of eurotransplant leiden , president of the austrian medical society of vienna , and member of the ethics committee of the austrian medical association ) . emeritus assistant clinical director of the clinic for anaesthetics and general intensive medicine , vienna , austria . clinical investigator and legally sworn expert . he received a doctor s degree in 1963 and started a specialist training which he finished in 1969 as a specialist for anaesthetics . later he moved as austrian un - soldier to cyprus , afterwards to the albert einstein college of medicine , new york . in 1979 but he did not stay there : he became head of anaesthetics and intensive care department of the children hospital modid in tehran , iran . after his return he is named assistant medical director of the ahk vienna and finally assistant board director for the clinic for anaesthetics and general intensive care medicine vienna . he engages himself to a high degree in different ethics committees ( vice director of the inter - faculty institute for ethics in medicine , vice director of the ethics committee of the vienna medical faculty , chairman of the ethics committee and board - member of eurotransplant leiden , president of the austrian medical society of vienna , and member of the ethics committee of the austrian medical association ) .
in infectious diseases we can discern a cause and effect chain , which in particular offers the practicable perspectives of prophylaxis and treatment . 
 however , to date we have not been able to control them . 
 apart from new epidemics , such as those caused by hiv and sars , long - forgotten scourges like tb are enjoying a comeback . 
 furthermore , the advances made in clinical medicine mean that induced immunosuppression , for instance as a result of major surgery or organ transplantation , has become a serious problem in intensive care units . 
 the body s natural barriers are breached through medical interventions while , on the other hand , immunocompromising therapeutic agents such as cytostacis and glucocorticoids ensure that invading microorganisms will be able to multiply . 
 drugs administered as stress ulcus prophylaxis give rise to a shift in the bacterial flora of the throat , thus laying the foundation for a lower respiratory tract infection . with regard to bacterial resistance , antibiotic therapy , especially when used as prophylaxis , results in the bacteria becoming less sensitive to the drugs , while reinforcing selective pressures . 
 the hands of personnel as well as the therapeutic devices ranging from the respirator to the catheter are the chief sources of infection in intensive care units . 
 disinfection , antibiotic therapy and , possibly , extracorporeal elimination methods can be contemplated to selectively prevent the establishment and multiplication of microorganisms . 
 however , only disinfectants are able to unleash their full destructive might against microbes , especially when used for medical devices that are not amenable to sterilization , even if their subsequent removal and , possibly , the issue of staff hand protection , can be a problem . while it is not easy to furnish proof of a direct link between efficient control and prevention methods and the incidence of infection , 
 there is by now a consensus on the role of hand hygiene and of disinfection of the human body and of surfaces . in an age 
 when medicine , in particular intensive care medicine , is at risk of becoming impaled on its own sword , disinfection could serve as a bulwark against rising infection rates .