Impact of portable air filtration units on exposure of haematology-oncology patients to airborne Aspergillus fumigatus spores under field conditions.

We undertook a one-year study to investigate the impact of the NSA model 7100A/B portable air filtration unit on exposure of haematology-oncology patients to airborne Aspergillus fumigatus spores under field conditions. Weekly measurements for airborne A. fumigatus were conducted in indoor and outdoor air, and surveillance for invasive aspergillosis was based on a combination of ward liaison, targeted chart review and consultation with the medical staff. The mean indoor A. fumigatus counts (8.1 cfu/m3; range, <0.8 to 42 cfu/m3) reflected the fungal load of outdoor air (9.4 cfu/m3; range, <0.8 to 50 cfu/m3), and were reduced by only about one third in rooms with portable air filtration units (5.3 cfu/m3; range, <0.8 to 41 cfu/m3). During the study period, a total of five cases (incidence density, 0.8 per 1000 patient-days) of invasive aspergillosis (one proven case, four suspected cases; case fatality rate 40%) were recorded. None of these five patients was allocated to a room with portable air filtration unit, however, the difference between incidence densities in rooms with and without portable air filtration units was non-significant (Fisher's exact test, P=0.33). Due to the noise level and thermal discomfort, patient compliance with the air filtration units was poor. We conclude that under field conditions this air filtration unit cannot be recommended for prevention of invasive aspergillosis in neutropenic haematology-oncology patients.

Pseudomonas aeruginosa outbreak in a haematology-oncology unit associated with contaminated surface cleaning equipment.

An outbreak of six cases of hospital-acquired Pseudomonas aeruginosa infections (two pneumonia two septicaemia, two skin/wound infection) occurred between August and September 2000 in an adult haematology-oncology unit at a tertiary-care centre. During the outbreak, hospital-acquired infection (HAI) incidence density rates rose from 29.4 to 62.3 (P < 0.05) infections per 1000 days at risk (i.e., neutropenic days). A systematic outbreak management system was actioned in accordance with a German draft guideline. Multiple samples from the patients' environment were tested for the presence of P. aeruginosa. A total of 4.5% of samples from sanitary equipment and 20.0% of samples from surface cleaning equipment were found to be contaminated with P. aeruginosa. Genotypic analysis by pulsed-field gel electrophoresis showed different patterns for all (N = 6) of the patient isolates, however, two of the patient isolates were identical in comparison with environmental isolates from cleaning equipment (four samples) and sanitary equipment (one sample). Our investigation revealed that the cleaning staff had used cleaning solution instead of disinfectants for decontamination of the patients' environment. The outbreak was terminated after re-adoption of surface disinfection, application of sterile filters on taps and shower heads, chemical disinfection of the washbasin drains, and appointment of a hospital hygiene nurse to a previously unfilled position. After institution of the control measures, HAI incidence densities decreased to pre-outbreak level. This investigation emphasizes the need to carefully evaluate cleaning and disinfection practices for patient care, particularly in neutropenic patients.

GIS-supported investigation of a nosocomial Salmonella outbreak.

Within an outbreak at a university hospital 102 persons (44 patients, 26 nursery school children and one relative as well as 31 employees) have been diagnosed to be infected by Salmonella enteritidis. Ninety-nine persons complied with the "primary case"-definition. The source of infection could not be detected in retrospect by hygienic-microbiological methods due to missing food samples. But GIS (Geographical Information System)-supported epidemiological investigation and analysis of food production showed that most likely vanilla pudding had been the vehicle of infection. Contamination of the pudding could be put down to the fact that its production took place in direct spatial and temporal association with the preparation of turkey. Probably further infections caused by this primary source were avoided by immediate measures. The making out of an HACCP-concept as well as structural and technical short-term redevelopment measures proved to be decisive factors to decrease the risk of further infections. From these experiences, some recommendations could be derived for the investigation of food-borne outbreaks in hospitals.

[Microbial contamination of wash water in automatic washing and disinfection machines]. / Mikrobielle-Kontaminationen von Spülwasser in Reinigungs- und Desinfektionsautomaten.

Samples were taken from the water containing tube system of 7 cleaning and disinfection machines located at the university clinics. The machines were used for the treatment of medical tools. The samples were bacteriologically examined. The results showed systemic contaminations of the tubes of all tested machines. The well known positive effect of common ion-exchangers on bacterial growth was not the only reason for the high degree of microbial contaminations. Partial bacterial growth on the inner sides of the water tubes was detected. The reason was the use of bacteriological objectionable tube materials. Recontamination of the post treated medical tools is possible at any time by the last washing water. Preceding sterile filtration showed as supposed no effect. Consequences for the use of cleaning and disinfection machines are discussed.

[Aspergillosis following liver transplantation as a hospital infection]. / Aspergillose nach Lebertransplantation als Hospitalismusinfektion.

In the first four weeks after a liver transplantation, there was an invasive aspergillosis with a lethal course in three out of five patients who were treated postoperatively in the same room. The clinical symptoms were very different. One patient was asymptomatic, and the diagnosis could only be made by autopsy. In another patient, pulmonary symptoms, and in the third patient, cerebral symptoms were the most prominent. In the two latter patients, the infection was demonstrated in the sputum and by bronchoalveolar lavage. The disease course was fulminant in all patients, and therapy was without success. Owing to this high incidence, mycological investigations were carried out on the ward. A flower bench in the hall beside the ward was probably the main focus of distribution. To avoid such nosocomial infections, foci of aspergillus distribution should if possible be removed from the surroundings of patients with weakened immune resistance.

[Identification of bacteria from use-surface disinfectant solutions and their sensibility against disinfectants (author's transl)]. / Bakterien aus Flächendesinfektionsmittel-Lösungen und deren Empfindlichkeit im Suspensionstest.

The investigations are concerned with bacteria which had been isolated from use-surface disinfectant solutions originated from 19 disinfection dosage apparatus of different hospitals and from 8 taps of a centralised disinfection dosage apparatus in an other hospital. The greatest part of the isolated bacteria belonged to the genus Pseudomonas. Beyond it there were yellow-pigmented bacteria like Xanthomonas, Flavobacterium and Micrococcus. After subculture on solid peptone-containing media most of the isolated bacteria turned out to be sensitive to the disinfection solutions in a concentration range, that had been applied in the dosage apparatus. The examination of 6 disinfectants showed, that there were considerable differences in the efficiency to kill the bacteria. Even one preparation pointed out to be absolutely ineffective at applied concentrations.

[Microbial emission, immission and changes in the germ count in the cooling water during operation of wet cooling towers. IV. Communication: microbial immission in the vicinity of wet cooling towers (author's transl)]. / Mikrobielle Emission und Immission sowie Keimzahländerungen im Kühlwasser beim Betrieb von Nass-Kühltürmen IV. Mitteilung: Die mikrobielle Immission in der Umgebung von Nass-Kühltürmen.

From the emission rates of the bacterial cooling tower emission determined in field measurements (see Comm. II) the mortality rate of enterbacteria on soil, grass and solid surfaces and the mortality rate in the atmosphere taken from literature the immission rates and the long-term effect on microbial surface flora were calculated and compared with our own measurements. The values used in the calculations include large margins for error. The atmospheric germ counts determined by experiment were no higher than the calculated values; they fluctuated in terms of concentration between 20 KBE m-3 and 200 KBE m-3 in ranges which were measured in areas with little or no anthropogenic influences. The maximum long-term surface load which occurs under these assumptions is 2.3.10(5) KBE M-2. This relatively small additional load (approx. 10(-3%) would hardly be noticeable in a number of colonies of approximately 10(10) KBE m-2 normally occurring in soil and grass samples.

Experiences and problems in the disinfection of fibre endoscopes.

The problem of the disinfection of fibre endoscopes is to achieve a good efficiency together with easy handling. There is not yet a disinfectant which shows a sufficient germicidal effect after a short time of contact with the fibre endoscope and which is harmless to the patient and medical staff. This paper deals with a two-stage disinfecting procedure in which the instrument undergoes a short intermediate disinfection using polyvidoneiodine (Betaisodona) between two investigations and a main disinfection at the end of a series of investigations using glutardialdehyde (Cidex). The measures lead to a sufficient reduction of the number of germs. The importance of the disinfection of all parts of the endoscopes, especially the channels and the accessories (water bottles etc.) is pointed out.