The detection of Legionella sp. in various types of environmental water samples was evaluated using a revised version of the EnviroAmp Legionella kit (Perkin-Elmer), which is based on the polymerase chain reaction (PCR). The new kit employs a modified protocol for the pretreatment of water samples, which is designed to further reduce the inhibitory action of some samples to the PCR. The results of the new kit were compared with those of culture. Seventy-four water samples were examined. Of these samples, 51 were taken from hospital water systems, 16 were household water samples, 5 were from surface water, and 2 were rain water. These samples were examined both by PCR and by culture on MWY Legionella selective agar. Of the 74 samples, 46 (62%) were positive by both test systems. Twenty-five samples (34%) were positive by PCR, but negative by culture. While 3 samples (4%) were negative by both test methods, no sample was negative by PCR and positive by culture. Statistical analysis revealed high positive predictive values of PCR, when L. pneumophila was detected or when the genus Legionella was detected at high intensity. Negative predictive values were high, when the PCR was negative or only weakly positive for the genus Legionella.

The objective of our investigation is to establish and explain the contamination of dental treatment units on the basis of a theoretical model, as well as to develop solutions to problems. In a first longitudinal study (6), facultatively pathogenic bacteria were identified in the operating water of dental units; the legionellae findings in screening were verified in a second longitudinal study with consideration of possible causal factors of bacteriological and parasitological nature. We took samples from the dental units and the water conduit system (cold and warm water in the dental surgery, cold water in front of and behind house internal accessory installations) in seven practices at ten measurement times over a period of ten weeks. Microbiological diagnostics were carried out with regard to the occurrence of legionellae, amoebae, pseudomonads and coliforms. The correlation between the metal content of the water and the occurrence of legionellae described in the literature caused us to determine the copper, zinc and iron content of the waters (according to standard German method, 1985). In addition, the physical-chemical parameters temperature, pH value, conductivity and oxidizability as well as the total hardness were determined. The findings in the first phase of the study could be confirmed both qualitatively and quantitatively in the second phase. However, a greater diversity of species was shown with regard to the occurrence of legionellae in connection with an enlarged sample. We were able to isolate free-living amoebae from all dental units, the identification of which was carried out in parallel to that of legionellae in the context of the second investigation (26). With a high variance of the contamination spectrum between the individual practices and the various units within each practice, generalization of the results is not possible; the findings are hence illustrated with examples from selected practices with consideration of the initial and interaction conditions.

In view of the risk of infection of the dentist and his staff in the dental surgery and dental laboratory and also of the patient with regard to hepatitis B and potentially also of AIDS, interruption of possible chains of infection by means of specific disinfection measures is to be demanded. Whereas appropriate hygiene concepts exist for disinfection of instruments, surfaces of equipment and furniture with regard to selection and application of various methods which may be considered, there are still extensive deficits for the domain of impression materials and their possible decontamination. In this regard, dentists frequently lack information with an adequate scientific basis that is understandable and oriented to practical requirements. Owing to the diversity of materials and their different behavior (cf. Tab. 1), appropriate recommendations can only be made on the basis of extensive studies. We assume that a practically relevant procedure must meet the following requirements: 1) sufficiently high rates of bacterial reduction in accordance with the guidelines of the DGHM, 2) lack of alterations in the dimensions or surfaces of the materials, 3) universal applicability, 4) practicability within a time period which is acceptable for smooth operation of the practice, 5) can be employed without problems for the staff. The object of the report are bacteriological results and materials testing data for the application of various methods of disinfection to selected impression materials. To summarize, it can be stated with regard to the bacteriological results that disinfection of impression materials is possible with fulfillment of the criteria specified above, but that there is a pronounced dependence of the results on the product formulation of the disinfectant and also of the impression material (cf. Fig. 4 and 5). Investigations of the material-related effects of the disinfection measures showed that extrapolation of the findings from one group of materials to another is also not possible in this connection, and that moreover the materials used to produce the model must also be included besides the impression materials used (cf. Fig. 9). Accordingly, statements on the suitability of a disinfection procedure are present admissible at most for the respective combination of materials tested, which makes practical introduction problematical.

In a longitudinal study over a period of ten weeks, the water conduit systems of seven dental surgeries with a total of 20 dental units in which legionellae had been detected in an earlier study (3) were investigated as a complement to extended microbiological tests (4) for the occurrence of free-living amebae and other protozoa. In 96% of all water samples, one or several ameba species were detected. These included 14 strains of the genus Naegleria, but no acanthamoebae. The naeglerias isolated were not thermophilic and thus belong to the N. gruberi complex, which does not contain any pathogenic strains. In two water samples, two different species of small freeliving nematodes were demonstrated. The simultaneous investigation of samples from the warm water supply in the individual dental surgeries revealed an ameba contamination in 24.9% of the samples. A nonpathogenic strain of the genus Protacanthamoeba was demonstrated once. The possible role of the trophozoites of various ameba species as hosts for an intracellular proliferation of the legionella strains demonstrated at the same time (cf. 4) is discussed. The occasional protective intracellular inclusion of legionellae in trophozoites of various species and in cysts of acanthamoebae might be an explanation for the resistance of legionellae to disinfection measures which has been repeatedly observed. This observation will have to be taken into consideration in sterilization and disinfection projects.

Twenty-one patients with carcinoma of the larynx, hypopharynx and the tongue underwent surgery under perioperative prophylaxis with cefmenoxime and metronidazole. Healing was uneventful and the clinical and the chemical parameters remained normally. The level of the antibiotics was effective against most of the bacteria cultured from tracheal aspirate and the posterior wall of the oral cavity. Effective perioperative antibiotic prophylaxis is necessary in head and neck surgery: the use of simple antibiotics in short courses should be assessed.

The point of this study was to analyze the possible benefits of perioperative antibiotic prophylaxis in patients from whom oral cavity or throat tumors are removed. The criteria used to judge the efficacy of each treatment included the clinical course of the treatment, the bacterial colonization of the surgical area as well as the growth of bacteria during the postoperative phase. 50 patients were chosen and grouped according to their surgical treatment: laryngectomy (n = 20), partial laryngectomy (n = 22) or tongue, floor of the mouth, soft palate, gum or base of the tongue partial resection (n = 8). Within each surgical group, patients were randomly chosen for antibiotic prophylaxis; others constituted the untreated control group. The antibiotic prophylaxis consisted of 5 g Mezlocillin administered at the time of narcosis for 20 min followed by 0.5 g Metronidazol for 10 min. These medications were given in 8-hour intervals for three days following surgery. Investigation of the first 20 patients (prophylaxis group n = 7, control group n = 13) revealed that the combination of Mezlocillin and Metronidazol positively influenced post-operative recovery (no complications) while the patients without prophylactic antibiotic treatment suffered general or local complication leading to, in 10 cases, the necessity of postoperative therapy. On the basis of these results, the random grouping of the patients was ended and all 30 remaining patients were given the antibiotic prophylaxis. Regardless of antibiotic treatment, the great majority of microbes isolated from throat swabs and tracheal secretions were gram-negative, aerobic bacteria. A prerequisite for efficacious prophylaxis is that the antibiotics be applied before the operation, so that a sufficient concentration is present at the time of pharyngotomy. On the basis of pharmacokinetic investigations, administration of the antibiotic 30 min preoperatively fulfills this requirement. Further, our recommendation, based on our measurement of the spectrum of bacteria present and their growth is that the antibiotics be applied over a period of three days postoperatively. This recommendation is also based on the fact that some patients (those having undergone partial laryngectomy or tongue, floor of the mouth, base of the tongue partial resections) have suffered loss of the swallowing reflex so that there exists a continuous contamination of the surgical area with pathogens or facultative pathogens coming from the nasal or oral cavities.

Using the "Natural" computer language a menu-guided system for cataloguing, processing and evaluating bacteriological and chemical water analyses was designed. The program can be employed to different blocs of analyses, e.g. "TrinkwV"-analyses, standard-analyses, those on volatile chlorinated hydrocarbons and bacteriological water analyses as well. For each water sample the actual, the last and the next to the last value, also arithmetical means, minimal and maximal are stored and can be retrieved. The evaluation of the bacteriological analyses and those of the volatile chlorinated hydrocarbons is carried out by a choice of text variants, whereas the TVO- and standard-analyses are interpreted automatically. Managing laboratory data has become much easier during our three years experience using this system for information storage, search and retrieval in water research and routine; even untrained users are able to handle it after a short period of tuition.

The subject of the study is a systematizing analysis of present research concerned with the barriers which prevent scientific findings about hygiene from being carried out and which hamper the obvious adoption of hygienically and psycho-hygienically relevant prophylactic measures. A general interpretive model with explanatory value for health- and hygiene-related behavior is being developed. Future studies will particularly have to clarify what significance and what interpretative relevance do the diverse influencing factors have for a particular person in a particular position and situation and how in the course of one's biography even something like lifestyles of hygienic behavior develop and change. For the necessity of improvement as regards the hygienic status in various realms of life the knowledge about existing barriers is a basic essential. The following quantities and constructs pass into the theoretic interpretive model which should also provide the basis for further evolvement of theories as well as the starting point for specific research hypotheses but not least for the development of specific research and evaluation designs: Standard of information, informational behavior and quality of information. The individual risk assessment: A function of the subjective importance and probability that benefit and cost factors of prophylactic behavior will occur. Additional influencing factors essential to the development of a desirable health- and hygiene-related behavior are: Objective shortcomings with regard to prophylaxis: deficits of the hygienic research including the deficits concerning the development of feasible and universally applicable disinfection methods. Hazards connected to prophylaxis: Objective risks with regard to prophylaxis (disinfection methods which may cause allergies, which involve problems with the compatibility of materials and so forth) and psychological risks (impaired relations between physician and patient due to the wearing of a mouth guard in dental practice, and others) are being differentiated. The degree importance attached to hygiene in organisations: prerequisites for this are: matters of hygiene as features characteristic of a specific job and as a part of employee evaluation, laying down of responsibilities and spheres of competence in matters of hygiene, normative binding character of job-related hygienic guidelines, exemplary behavior of the management.(ABSTRACT TRUNCATED AT 400 WORDS)

In a psychological exploration study 40 dentists were interviewed on the basis of an attitude-orientated decision-making model; 20 of them also made dental units in their consulting rooms available to M. Borneff (10) for analysis and examination. Both subsamples are comparable in terms of structure; differences in the way of answering were not detected. The study focuses on the analysis of complex psychological barriers which would permit us to explain and predict unsatisfactory hygienic behavior in dental practice. The following major results deserve attention: Hygiene and infection prophylaxis in dental practice are questions of relatively high current relevance and sensitivity. The dealing with hygienic hazards and related prophylactic measures is relatively varied and indicates that dentists are willing to further receive and absorb information. But the elimination of possible risk factors is impaired by a variety of psychological barriers which do not exist independently from each other and which also tend to reciprocally intensify one another: Barriers for lack of knowledge While interviewees attribute increasing significance to hygiene in the study of dentistry, the compulsory subject hygienics plays a rather minor role within one's individual education. Knowledge in the field of hygiene and hygienic behavior are essentially a question of further training. But sources of information providing additional continued training are used rather sporadically and judged diversely. Incomprehensibilities and inconsistencies in scientific publications, unsatisfactory effectiveness and practicability of possible hygienic measures do not contribute to a coherent, systematic formation of opinion relevant to behaviour. Deficiencies in terms of knowledge also occur in dental assistants who play a crucial role in carrying out hygienic measures in dental practice. Barriers on account of probability Being aware of the essential hygienic risk factors (dental staff and patients, handpieces and angle pieces, dental impression materials, instruments, dental units) and also knowing of possible prophylactic measures the subjective probability that hazards will actually occur in one's own dental practice is low; only in a few individual instances a hazardous case was encountered already once before. The willingness to invest in statistically only probable and remote (in terms of time) risk eventualities, i.e. the readiness to bear objective as well as psychological "costs" without guarantee of amortization, is only slight. Barriers on account of problems.(ABSTRACT TRUNCATED AT 400 WORDS)

Within a scope of an investigation concerning hygiene-problems in dental practice a longitudinal study was carried out in 20 dental offices with 53 units. In order to guarantee equal experimental conditions and to eliminate variations caused by changing water flow during the day, we took the samples before office hours alternating mondays, tuesdays and wednesdays. Those samples gathered from all handpieces (n = 530) and the drinking water faucets (n = 200) were examined according to the "Trinkwasser-Verordnung" (1986), diagnostics were supplemented concerning special groups of bacteria (see also Table 1). Analyses of copper, zinc and iron were done once during the study. Selecting certain sampling spots (see also Table 2) the surface contamination of the units and the surroundings was examined using the "Rodac"-method (n = 4800). The results of the study may be summarized as follows: The investigation concerning the surface contamination showed under qualitative and quantitative aspects (see also Fig. 10) constant contaminations on the patients' head- and armrests, the operating lamp, cuspidor-bowl and hand-wash-basin. In samples taken from the water system of dental units potentially pathogenic bacteria were isolated in 71%, in first place Ps. aeruginosa, followed by Ps. acidovorans and other species of this group. Legionella species occurred sporadically in the units and potable water of 8 offices. On the base of the total germ count (22 degrees C and 37 degrees C) the diagnosis "drinking-water quality" was possible only in 31%. The longitudinal investigation showed, that the contamination of the water system follows different progressive forms regarding extent and quality (see also Fig. 7). Relating to these results in the first step the development of a theoretical model concerning the different influencing factors (quality of water tubes and other devices, variation of temperature, quality of potable water and the effect of ionic exchangers, indirect contamination by patients and dental staff, nature of dental treatment, utilization frequency of the direct handpieces) appears to be necessary. Thus the contamination has to be understood as a developing process determined by specific promotors and catalyzers; in the second step the evaluation of adequate bactericidal and virucidal decontamination procedures fitting into the daily practical needs of dental offices should follow.