Biomedical subjects
Publications and source records attributed to G Reybrouck.
The authors describe the organization of infection control in Belgium with respect to official regulations, the tasks and the training of the infection control doctor and of the infection control nurse, functioning of the infection control committee, the financing and the availability of guidelines.
Imported vs. hospital-acquisition of MRSA was assessed in > 6000 patients at a large tertiary care teaching hospital. About five percent (5.1%) of patients carried MRSA on admission, mostly without clinical symptoms; the highest percentage (11.6%) being in geriatric patients. Hospital-acquisition of MRSA occurred in 1.7% of patients and was particularly high in intensive-care units (5.2%). Phenotype and genotype analysis of 158 MRSA strains isolated from 61 patients revealed a cluster of closely related strains in the hospital-acquired MRSA infections and the close relationship of this cluster to the regional epidemic MRSA strain. The MRSA strains imported by geriatric patients were genetically different, did not spread between geriatric patients and were only a minor source of nosocomial infection.
Besides an atraumatic procedure, aseptic techniques during surgery have been suggested to have a positive impact on the predictability of osseointegration. To avoid an infection of the surgical field, coverage of the face of the patient (drapes) and nose (surgical mask, drape and plastic film) were advocated in order to reduce airborne infections and to prevent a contact contamination of instruments and gloves. Such a coverage, however, increases the feeling of claustrophobia when local anaesthesia is used and can lead to hypoxemia. The aim of the present study was to investigate whether the expired air via the nostrils could contribute to the contamination of the oral surgical field. Test blood agar plates were installed for 30 min under the nose of volunteers lying on a surgical table; once with full coverage of their nostrils, as indicated above, and once without. Simultaneously, control plates were installed on a table besides the patient to measure the basic contamination from the environment. All plates were incubated both aerobically and anaerobically. The number of colony forming units (c.f.u.) recorded on test plates after aerobic and anaerobic incubation were surprisingly low, with a mean score of 2.7 and 5.0 c.f.u. for the uncovered situation, and 2.5 and 3.3 c.f.u. for the covered situation, respectively. The control plates were infected by a nearly comparable number of bacteria (means ranging from 2.2 to 3.2). These findings indicate that covering nostrils by a mask and sterile adhesive plastic film is not essential in avoiding airborne microbial contamination. However, the use of a meshed nose guard to prevent contact with the highly contaminated nasal skin is highly recommended.
The situation of hospital hygiene in Belgium and in the Netherlands is described in the light of the official regulations, the composition and the functioning of the infection committee and of the hospital hygiene team, and the availability of official or semi-official guidelines. Typical for the Netherlands in the long tradition of issuing guidelines on hospital hygiene, in the beginning in 1966 in the form of an advice of the Health Council, at present in the guidelines of the Working Group on Infection Prevention (WIP). A particularity for Belgium is the financing by the state of the hospital hygiene doctor and the hospital hygiene nurses based on a system of scores in which the beds of specialisms with a higher infection risk count for more than general beds.
A thin-layer chromatography method for quantitative analysis of quaternary ammonium antiseptics is described. Silanized silica gel was used as the stationary phase. The mobile phase consisted of methanol-25% (m/v) sodium acetate solution-acetone (65:35:20). The method is able to separate the chain homologues of benzalkonium chloride, cetylpyridinium chloride and cetrimide. Detection was performed using a colour reaction with potassium triiodide solution. The different homologues were quantified using UV densitometry at 400 nm. A number of commercial samples was analysed using this method. From the results it appears that it is worthwhile to have a limit test for the composition of quaternary ammonium antiseptics in pharmacopoeial monographs, the more so as the antibacterial activity depends on it.
The AOAC use-dilution method was applied in order to assess the bactericidal activity of 29 commercial preparations for surface disinfection and the Kelsey-Sykes test under clean conditions for 38 preparations. The results of both tests are compared with those of the in vitro test (with the disinfectant diluted in distilled water, in water of standardized hardness, and in a 0.2% albumin solution), those of the European suspension test under clean and under dirty conditions, and those of four practical tests (the AFNOR test, the DGHM test, the QCT and the QSDT). Both the AOAC use-dilution method and the Kelsey-Sykes test under clean conditions are more severe than the suspension tests and, in the case of Pseudomonas aeruginosa, even than most practical tests. The results of both tests correlate well to one another, and to the results of in vitro test, but less to those of the European suspension test. For the practical tests the correlation depends on the testing technique and on the test organism.
The objective of this study is to determine to what extent the value of a preparation for surface disinfection in practice can be predicted by the usual tests, namely the in vitro test in which the disinfectant is diluted in distilled water, in water of standardized hardness or in a 0.2% albumin solution, the European suspension test under clean and under dirty conditions, The Kelsey-Sykes test under clean conditions, the AOAC use-dilution method, the practical tests of the AFNOR, of the DGHM, the quantitative carrier test QCT and the quantitative surface disinfection test QSDT. Therefore the results of all these tests are compared to the ranking order of the efficacy of the same preparations in practice tests, in which slides contaminated with stool or infected urine are disinfected. There is no correlation between the results of the suspension tests and those of the practice tests, but the practical tests (DGHM test, QCT and QSDT) correlate well with practice. Practical tests (second stage of the testing schedule) are therefore necessary for the evaluation of surface disinfectants, as suspension tests alone will not suffice.
At present there is no harmonization of antiseptic and disinfectant testing in the world, not even in Europe. In the case of surface disinfection the bactericidal activity of preparations is evaluated by very different techniques. The Association of Official Analytical Chemists of the USA prescribes a carrier test, the use-dilution test, to determine the maximum dilutions that are effective for practical disinfection. In Germany and in France, the final test for determining the use-dilution of a disinfectant preparation is a practical test mimicking conditions of use. In the UK the Kelsey-Sykes test, a capacity test, is more popular. The Council of Europe prescribes a quantitative suspension test with organic load, the European Suspension Test (EST), as the definitive testing method for disinfectants used in food hygiene. It is to be expected that these varied testing techniques would yield different results. The evaluation of a testing technique should be supported by correlation of the results of the tests with efficacy in practice. The recent founding of a technical committee of the European Committee for Standardization (CEN) raises great hope that, at least in Europe, a harmonization of the testing techniques will be possible in the near future.
The results of the testing of 38 preparations intended for surface disinfection are compared in order to evaluate the value of the suspension tests. The studied testing methods are: the in vitro test (IVT) with the disinfectant diluted in distilled water (AD), in standard hard water (WSH) and in 0.2% albumin; the European Suspension Test (EST) under clean and under dirty conditions; the French AFNOR test NF T 72-190; the practical test of the German Society for Hygiene and Microbiology (DGHM); and the Quantitative Surface Disinfection Test (QSDT). The suspension tests yield comparable results (Table 1). These results correlate very well with these of the AFNOR test, to a lesser extent with those of the DGHM test and hardly with the results of the QSDT, which is the most real-life mimicking practical test (Table 2). Suspension tests are not able to exclude only inactive preparations from further testing in practical tests: they are not specific (Tables 3 and 4). Therefore, it is necessary to include practical tests in the testing schedule for the evaluation of the bactericidal activity of surface disinfectants.
Many experimental methods have been used to assess the efficacy of products intended for surgical hand disinfection. In this study, a modification of the Peterson glove juice method was used to compare two chlorhexidine-based surgical hand disinfectants, 'Hibiscrub' and an experimental formulation, F.6115. The study was performed by four independent laboratories and data merged for analysis. There was found to be no significant difference between the two formulations. The results illustrate that this modified Peterson glove juice method has the potential to form the basis of a standard method for testing surgical hand disinfectants which is both relevant to the practical situation and reproducible in different laboratories.
Three tests intended for the assessment of the bactericidal activity of surface disinfectants are compared. They are the French AFNOR test (AFNOR NF T 72-190: détermination de l'activité antibactérienne pour la décontamination des surfaces--méthode des portes-germes), the German DGHM test (Deutsche Gesellschaft für Hygiene und Mikrobiologie: Flächendesinfektionsversuch unter praxisnahen Bedingungen) and the Leuven test. From the theoretical analysis of the different elements of the testing techniques in which the three methods differ, it was deduced that it should be easier to pass the AFNOR test, since relatively more disinfectant solution is available to kill the same number of bacteria, whereas the Leuven test is the more severe, because the bacterial inoculum is larger and the germs are more protected by organic matter. The same differences are found in practice. This is demonstrated by the comparison of the results for 38 disinfectant preparations: the microbicidal effect obtained (log reduction factor, RF) is the lowest in the results by the Leuven test, and the best results are obtained in the DGHM test; this difference is found statistically significant in the Wilcoxon rank sum test for paired samples It could be that because of the different norm (the Leuven test for 30 min requires only an RF of 4.0, whereas the norm for the other tests is 5.0), the number of preparations passing (or failing) a test is the same, or that at least a preparation passing the more severe test passes automatically the easier tests; this is not always the case If the notion of passing or failing a test is omitted, and the ranks of the test results are compared in pairs, then, however, a very significant correlation is found among the test results, although to a lesser extent for the AFNOR test versus the Leuven tests in case of Pseudomonas aeruginosa. It can be concluded that the three testing techniques yield comparable results (correlation of the ranks), although a preparation passing a severe test does not automatically pass a less severe test. In any case there is a marked difference in the severity of the testing techniques and this is not neutralized by adjusting the required norm only.
The Dutch quantitative carrier test (QCT) prescribes the rinsing technique for counting the surviving bacteria after disinfection. This method is compared with the Leuven test, which uses the impression technique in order to determine the survival on the disinfected surfaces, and with a novel quantitative surface disinfection test (QSDT). The QSDT combines the preparatory and disinfection phase of the Leuven test with the postexposure rinsing technique of the QCT. The results of the three tests correlate very well as is shown by Kendall's rank correlation test. The QCT and the Leuven test yield equivalent results: neither the median of the results, nor the paired results apart differ statistically for the same exposure time of 30 min. On the contrary the results of the novel QSDT differ in a statistically significant way from those of both other techniques, but the QSDT is more severe than the QCT and the Leuven test in the case of Staphylococcus aureus, whereas in the case of Pseudomonas aeruginosa it is the less severe one. This phenomenon can hardly be explained and emphasizes the importance of the resuscitation of sublethally damaged germs in the postexposure phase of testing.
The results of both previous articles on the comparison of practical tests for surface disinfection are summarized. They are the DGHM test of the German Society for Hygiene and Microbiology, the AFNOR test NF-T 72-190 of the French Association for Standardization, the quantitative carrier test (QCT) of Van Klingeren, the Leuven test and the quantitative surface disinfection test (QSDT). The comparison of the techniques followed in these tests seems to indicate that the differences in the operating technique are likely to influence the test results. There is, however, a close correlation among the results of all but the AFNOR test, although there remains a statistically significant difference in the reduction factors: the Leuven test and the QCT are the more severe tests, whereas the AFNOR and DGHM tests are the less severe ones. The QSDT gives divergent results, which could be attributed to the influence on the resuscitation of the surviving bacteria.
During the last week of May 1986, a 1-week prospective study on antibiotic utilization in surgical patients was held in 104 (42%) of the 247 Belgian acute care hospitals. All surgical patients with a post-operative stay of at least 3 days were studied, involving 3112 patients. Each patient was observed for 7 days, starting from the day before surgery. Antibiotics were administered to 71.9% of all patients; 21.9% received therapeutic antibiotics and 52.9% prophylactic antibiotics; 2.9% received both. Of the 1285 patients undergoing a surgical procedure with no indication for antimicrobial prophylaxis, 50.7% nevertheless received prophylaxis; 92.8% of patients with a generally recognized indication for prophylaxis received antibiotic prophylaxis. Less than one fifth (17.1%) of all prophylactic courses were stopped on the day of the intervention whilst 26.3% were continued up to the fifth post-operative day or beyond. The most frequently prescribed drugs for this indication included first and second generation cephalosporins and nitroimidazoles. The number of different generic drugs utilized per hospital ranged from 1 to 18 (mean: 7.7).
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A national one-day prevalence survey of nosocomial infections was carried out in March 1984 in 106 Belgian acute-care hospitals involving 8723 patients of whom 6130 had undergone surgery. Three infections were studied: surgical wound infection, bacteraemia and urinary-tract infection. One or more of these three infections was recorded in 9.3% of all patients and in 11.8% of surgical patients. Prevalences increased with increasing duration of hospital stay and with higher ages, but the association of HAI with age was no longer significant after correction for duration of hospital stay. Prevalences varied considerably in different specialties. After adjustment for age and duration of stay, there was no association between perioperative antibiotic prophylaxis and the prevalence of the infections studied, but bias due to selection of higher risk patients in the antibiotic group was probable. Larger hospitals had a higher overall prevalence, but populations differed according to the size of the hospital. Bacteraemia was strongly associated with the presence of an intravenous catheter, and urinary-tract infection with a urinary catheter.
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In order to standardize antifungal disinfectant testing using Candida albicans as a test organism, the morphology of four type strains of C. albicans DSM 1836, ATCC 10231, CNCM 1180-79 and CBS 562, grown on sixteen different media was determined. The incubation was carried out at 28 degrees C and 37 degrees C. The yeast phase was obtained predominantly on TSA medium with all strains. Mixed phases, i. e. true mycelium and yeast cells, were easily obtained in TSB in shaking flasks for three type strains but not for CBS 562. True mycelium was formed on corn meal media (CMA) for all strains, but the growth was very poor. The morphology of the growth was determined more by the type of strain than by the nutritive medium. Therefore C. albicans ATCC 10231 grown on either TSA or CMA was used as a test organism. Its resistance was determined towards four disinfectant standards: benzalkonium chloride, mercuric chloride, phenol and o-phenylphenol. No difference in sensitivity was found for the former disinfectant, but yeast cells grown on TSA were more resistant than C. albicans cultures on CMA in case of mercuric chloride, phenol and o-phenylphenol.