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Biomedical subjects

W Koller

Publications and source records attributed to W Koller.

136 records · Page 8Linked to original sources
PubMed1977

[Usability of three alcohols for a standard disinfection method to be employed for the evaluation of procedures for the hygienic disinfection of hands (author's transl)].

Following a former suggestion (4) always to evaluate, the efficacy of procedures for Hygienic disinfection of hands in comparison with the results of a certain standard disinfection method, Ethanol, iso- and n-Propanol were tested in various concentrations and for various times of action on their usability in such a standard method. The disinfecting power was dependent upon (i) the alcohol (Ethanol less than iso-Propanol less than n-Propanol), (ii) the concentration (Ethanol: 60 less than 70 less than 80% ml/ml, iso-Propanol: 50 less than 60 less than 70, n-Propanol: 40 less than 50 less than 60 = 70) and (iii) the time of action (0,5 less than 1 less than 2 min). n-Propanol proved to be the fastest acting disinfectant. However, as standard disinfection method iso-Propanol (60% ml/ml) being used for 1 min has been proposed. Furthermore, the following results that have been obtained also in former investigations (8) could be confirmed: (i) there is no systematic difference between the release of test-bacteria from the fingertips of right and left hands of test-persons (ii). The efficacy of procedures for Hygienic disinfection of hands is besides other factors influenced by the testpersons. This factor may be eliminated by using the same testpersons for both, the disinfection procedure under investigation and the standard method. The results of both may, then, be related to each other and the efficacy of the former may be evaluated in comparison to the latter.

1-Propanol↗
PubMed1977

[Testmethod for the evaluation of procedures for the hygienic disinfection of hands. Part 1: Discription of testmethod (author's transl)].

A detailed test design for the evaluation of procedures for the hygienic disinfection of hands is described together with suitable methods for statistical analysis of the results. In principle the release of testbacteria from the finger-tips of artificially contaminated hands is measured before and after disinfection. A procedure under test is accepted if it is not less effective than a standard-disinfection procedure. As such the disinfection with iso-propanol 60% (ml/ml) applied through 1 min was agreed upon. This standard procedure is to be performed the same day with the same day with the same testpersons and under identical environmental conditions prior to the procedure under test.

1-Propanol↗
PubMed1977

[Comparison of efficacy of 14 procedures for the hygienic disinfection of hands (author's transl)].

The efficacy of 14 procedures for the hygienic disinfection of hands mostly with commerical preparations was tested by a new experimental model developed at the Institute of Hygiene of the university Vienna (1,3). The disinfectant power was clearly dependent on the duration of treatment as well as on the kind of alcohol used in the preparation (n-Propanol better than iso-Propanol better than Ethanol). After one minute the efficacy of all preparations containing one of the three alcohols as active agent was well comparable to that of the standard procedure which according to our proposal (5) uses iso-Propanol 60% (ml/ml) for 1 minute. For preparations with n-Propanol as the main active agent (Satinazid and Sterillium) this was true even after treatment for a period as short as 0.5 min. In our opinion disinfecting detergents are out of place for hygienic disinfection of hands. One preparation representing this group (Versuchspräparat A) was far less effective than the standard procedure.

1-Propanol↗
PubMed1976

[The patient as a source of bacteria in intensive care units: influence of antibiotics and tracheal intubation (author's transl)].

133 patients in an intensive care unit, who prior to admission had not shown any signs of bacterial infection and had not received antibiotic treatment, were assigned to two groups at random. One group received antibiotic prophylaxis with penicillins or cephalosporins (+Pat.), the other group did not receive antibiotics (-Pat.). Staph. aureus was the most frequent facultative pathogen in tracheal secretions and in the environment of "-Pat.". This organism was significantly more frequent in "-Pat." than in "+Pat." in both the tracheal secretions and the environment. Klebsiella spp. outnumbered all other species in "+Pat.". They were significantly more frequent in tracheal secretions of "+Pat." than of "-Pat.". In the first week of hospitalisation marked changes were seen in bacterial flora of tracheal secretions of "+Pat.". Colonization with grammnegative bacteria rose to nearly 100%, the frequency of Staph. aureus diminishing at the same time. Monitoring by contact cultures revealed that gramnegative rods were significantly more numerous in the environment of "+Pat." than of "-Pat.". Matching bacterial strains cultured from tracheal secretions and from the environment of the patients proved that "+Pat. spread significantly higher numbers of their gramnegative bacteria into the environment. The same is true of "-Pat." for Staph. aureus. Intubation had no noticeable effect on the degree of contamination of the surroundings with Staph. aureus. Gramnegative rods were significantly more frequent in tracheal secretions of patients with intubation than in patients without. The same trend was observed for environmental contamination. As the clinical results of this study have shown, antibiotic prophylaxis does not protect patients from infections to the extent expected. Patients, and particularly intubated patients, receiving antibiotic treatment have to be considered as sources of highly resistant gramnegative organisms.

Anti-Bacterial Agents↗
PubMed1976

[Viable bacterial counts by agar-droplet technique (author's transl)].

This paper deals with 1) Analysis of the agar droplet technique for viable bacterial counts with respect to a new technical aid (Colworth DROPLETTETM); 2) Comparison of the results obtained from two conventional plate count techniques and the agar-droplet method; 3) Examples for the practical use of this new technique. As a helpful aid for the agar-droplet technique there now exists an apparatus (Colworth DROPLETTETM, Fig.1) which facilitates dilution and dispension of bacteria containing agar, as well as counting of colonies grown in agar droplets. Precision and reproducibility of the diluter/dispenser was found to be within the limits of the usual sampling error (Tab.1, Fig. 2, Fig. 3). The visibility of colonies grown in agar droplets is improved by a ten-fold enlargement on the ground glass screen of the viewer (Fig. 7). In order to obtain droplets of equal size a standardised dropping-technique is required. The fluid agar must not exceed a constant temperature of 50 degrees C as otherwise four of the five species tested (Staph. aureus, E. coli, Kl. aerogenes, Ps. aeruginosa and Enterococci) were significantly reduced in number during the manipulation (Fig. 4, Fig. 5). Agar droplet technique, flooding technique and pour plates gave similar results with gram-positive and gram-negative bacteria from medical routine materials. Comparing the arithmetic means, viable counts of Staph. aureus were slightly higher from pour plates while E. coli and Kl. aerogenes gave the highest counts on flooded plates (Tab. 8-11). All of the three methods produced relatively too low counts when the number of bacteria per sample surmounted 300. Counts below 10 allow only a very poor estimation of the actual number of bacteria (Tab. 12). The variability of droplet counts with bacterial numbers higher than 25 was less then the one of corresponding plate counts (Tab. 14-16). Significant savings in materials, labour and incubator space are made with the agar droplet method. As examples for the practical use of the new method the results of the kinetics of thermally inactivated as well as of growing bacteria are presented.

Agar↗
PubMed1976

[Kinetics of the release of testbacteria from the artificially contaminated hand (author's transl)].

It is demonstrated that the release of testbacteria from the finger tips of artificially contaminated hands is influenced to a very small degree only by application of the finger tip method when compared to the effect of ablutions. Therefore, without apprehension of influencing the post-values this method may be employed in order to assess pre-values as required by the test-model of Rotter and Mittermayer (5) for the evaluation of procedures for the hygienic disinfection of hands. In addition, it can be shown directly that it is irrelevant for the number of bacteria released after a germ-reducing procedure, whether the finger tip-method has been used or not, preceedingly. In contrast, all technical variations that aim at the restitution of the supposed loss of testbacteria (like renewed contamination after the assessment of prevalues) change the postvalues measurably and must be avoided, therefore. Drying of bacterial suspensions on the hands, as after artificial contamination, reduces the release of viable testbacteria depending on the time. This effect is stronger on the palms than on the finger tips. The influence of handbrushes on the release of testbacteria with simultaneous useage of detergents compares well with the effect of an alcohol disinfection. However, this method is not suitable to eliminate pathogens safely.

Escherichia coli↗
PubMed1975

[Thoughts upon the construction of requirements of disinfection procedures concerning contaminated hands - an analysis (author's transl)].

The construction of detailed test methods for the evaluation of disinfection procedures has primarily to be based upon requirements which have to be formulated in advance. A recently proposed test model is being discussed on the basis of 5 conceivable formulations of possible requirements. Essentially, they may be allotted to two types: the one implies the comparison of the disinfection procedure to be tested as against an hypothetical procedure. The other makes use of the simple comparison with a concrete standard procedure and is preferable to the first possibility for several reasons. The presented, mathematical formulations of the structure describing the proposed model represents a first approximation in order to permit the comparison of disinfection effects on the hands under assistance of probabilistic methods and eliminating other effects inherent ot a test method.

Disinfection↗