Surveillance of nosocomial infections in paediatric recipients of bone marrow or peripheral blood stem cell transplantation during neutropenia, compared with adult recipients.

The aim of this prospective study was to analyse the incidence of nosocomial infections (NIs) during neutropenia after haematopoietic stem cell transplantation (HSCT) in paediatric and adult patients. Diagnosis of NI followed the modified surveillance protocol of the German National Reference Centre for Surveillance of NIs. During the 24-month study period, 38 and 39 transplantations were performed in paediatric and adult patients, respectively. Eighty percent and 92% of the paediatric and adult patients, respectively, underwent allogenic HSCT. In total, 1156 neutropenic days were documented. The incidence of NI during neutropenia in all recorded cases was 38.9 NI per 1000 days, without significant difference between the groups. No difference was found in the incidence rates of pneumonia, while there was a trend towards a higher incidence of bloodstream infection in adult patients. Significantly more episodes of fever of unknown origin were found in paediatric than adult patients. Pathogens were isolated in 19 of 45 cases of NI. Of the clinically documented infections, Gram-positive organisms were isolated in 79%, Gram-negative organisms were isolated in 16% and fungi were isolated in 5%. Surveillance of NI is an effective instrument to control the quality of health care. It should focus on device-associated infections or specific high-risk targets such as nosocomial pneumonia.

Interdisciplinary clinical assessment of patients with illness attributed to environmental factors.

Patients with health problems attributed to environmental factors such as chemical pollutants and electromagnetic fields often do not present evidence of an environmental aetiology of their symptoms. It has been postulated, that their problems are due to disorders diagnosed by other medical disciplines, especially allergology and psychiatry. Our study was designed to subject these patients to a comprehensive diagnostic program involving several medical disciplines in order to achieve diagnoses appropriate to explain the patients' symptoms. Fifty patients consecutively referred to the department of environmental medicine in the university hospital of Aachen, Germany, were submitted to the following examinations: (i) environmental medicine (history, clinical examination, biological and/or ambient monitoring for environmental agents); (ii) allergological examination (history, clinical examination, skin tests); (iii) psychiatric examination (psychopathological examination, psychometric and neuropsychological testing). In addition, the patients were examined in other hospital departments according to the symptoms presented. The findings were discussed in case conferences attended by the physicians involved in order to achieve individual diagnoses. The numbers of patients to whom diagnoses were given by different medical disciplines are as follows: psychiatry (32 patients), dermatology (4), allergology (2), neurology (2), rheumatology (2), gynaecology (1), haematology (1). The most frequent mental disorders diagnosed by the psychiatrists were somatoform disorders (19), followed by schizophreniform and delusion disorders (7). In spite of extensive diagnostic efforts, patients with health problems attributed to the environment usually do not present sufficient evidence of an environmental aetiology of their symptoms. On the other hand the symptoms often meet the diagnostic criteria of other diseases, especially of mental disorders.

Comparison of membrane filtration methods for the recovery of legionellae from naturally contaminated domestic drinking water supplies.

We compared four methods for the cultural recovery of legionellae from naturally contaminated water samples: (A) inoculating 1 and 0.1 ml directly on the selective solid growth medium, (B) filtration through cellulose nitrate membrane filters and inoculating the resuspended residue corresponding to 100 and 10 ml of the original sample on the medium, (C) filtration through polycarbonate filters and inoculating the resuspended residue corresponding to 100 and 10 ml of the original sample, and (D) filtration of 100 and 10 ml through cellulose nitrate filters and incubating the filter directly on the medium. Of the water samples tested in parallel, 103 samples tested positive for legionellae in at least two of these methods. The mean number of CFU/ml recovered by methods A, B, C, and D werte 5.45, 1.85, 1.70, and 2.26, respectively. The differences between the methods proved to be highly significant except for methods B and C (p = 0.112), the results of which correlated closely with each other (r = +0.96). In comparison with method A the recovery rates of methods B, C, and D were found to be 60, 57, and 69%, respectively. We recommend the use of method A for the recovery of legionellae at concentrations of > or = 1 CFU/ml. If legionellae below this concentration are to be detected we recommend method D as the easiest and most sensitive technique.

Heterogeneity and clonality among isolates of Mycobacterium kansasii: implications for epidemiological and pathogenicity studies.

The reservoir and transmission route of Mycobacterium kansasii are largely unknown. In addition, culturing of M. kansasii from human sources is not proof of disease because it may represent colonization rather than infection. Unfortunately, investigation of the epidemiology and pathogenicity of M. kansasii is complicated by evidence of heterogeneity within the species. A comprehensive study by detailed genotypic analysis of a large collection of M. kansasii isolates (n = 276) from various geographical sources within Europe was conducted. Five defined subtypes of M. kansasii were identified; of these subtypes, type I represents the most common isolate from humans. Although phylogenetic analysis confirmed its relationship to the other M. kansasii types, significant sequence divergence was found at the 16S-23S intergenic spacer. Analysis of the chromosomal polymorphism of type I demonstrated a marked clonal structure for this particular organism. Because M. kansasii is becoming a significant pathogen among immunodeficient hosts, future epidemiological and pathogenicity studies should take into consideration both the heterogeneity within the species and the apparent clonality of the most prevalent M. kansasii isolates infecting humans.

Comparison of methods for isolation of mycobacteria from water.

Twelve methods for the isolation of mycobacteria were compared by applying them in parallel to 26 samples of surface water and 109 samples of treated water. Each method was defined by a particular combination of decontamination method, growth medium, and incubation temperature. For the decontamination of surface water, we used cetylpyridinium chloride (CPC) (30 min, 0.05%), as well as sample preincubation in tryptic soy broth (TSB) followed by decontamination with a cocktail of NaOH, cycloheximide, and malachite green. Treated water was decontaminated with 0.005 and 0.05% CPC (30 min). After enrichment by filtration, all samples were incubated on Lowenstein-Jensen medium (LJ), Ogawa egg yolk medium (OEY), and Ogawa whole-egg medium containing ofloxacin and ethambutol (OEOE) at temperatures of 30 and 37(deg)C. The efficacy of each method was determined by calculating the positivity rate, negativity rate, contamination rate, mean number of mycobacterial colonies grown, and mean number of different mycobacterial strains isolated. The last value was determined by subjecting the isolates to PCR restriction analysis and mycolic acid thin-layer chromatography. Statistical analysis demonstrated that both the TSB method and 0.05% CPC were appropriate for the decontamination of surface water. Decontamination with 0.005% CPC was best for treated water. The results for incubation on LJ were at least equal to those for incubation on OEY and always superior to the results with OEOE. At an incubation temperature of 30(deg)C, all methods achieved higher yields than at 37(deg)C.

Dental units: an environmental study of sources of potentially pathogenic mycobacteria.

SETTING: Infections caused by non-tuberculous mycobacteria (NTM) are generally thought to be acquired from environmental sources. However, little is known about the situations in which transmission occurs. OBJECTIVE: In an attempt to identify situations of relevant contact with NTM we investigated the water to which patients are exposed during dental treatment. DESIGN: The concentration and species of NTM were determined in 43 cooling and spray water samples from 21 dental units in ten offices. In addition, mycobacterial colonization of 16 biofilm samples from the waterlines of two dental units was investigated. RESULTS: The mean NTM concentration in the water samples was 365 colony-forming units (cfu) per mL, exceeding the mean drinking water concentration by a factor of almost 400. In the biofilm samples the mean NTM density amounted to 1165 cfu/cm2. The species identified included Mycobacterium gordonae, M. flavescens, M. chelonae, 'M. chelonae-like organism' and M. simiae. CONCLUSION: High numbers of NTM may be swallowed, inhaled or inoculated into oral wounds during dental treatment, possibly resulting in colonization, sensitization or infection. Mycobacterial proliferation in biofilms forming within dental units may explain the extent of NTM contamination of dental spray and cooling water.

[Mycobacteria in the environment]. / Mykobakterien in der Umwelt.

Mycobacteria typically are free-living environmental saprophytes and strict pathogens such as M. tuberculosis and M. leprae, which do not proliferate in the inanimate environment form rare exceptions within the genus Mycobacterium. Many free-living mycobacteria such as M. avium and M. kansasii have been described as potential human pathogens and there is evidence that they are usually transmitted by inhalation, inoculation and ingestion from environmental sources. Soil, bogs, surface water, ground water and sea water have been described as natural habitats of environmental mycobacteria. In addition, artificial habitats such as tap water and sewage sludge are colonized by a considerable spectrum of mycobacterial species. Aquatic mycobacteria tend to colonize biofilms at air-water and solid-water interfaces and the latter seem to be an important proliferation site in oligotrophic habitats. Outside the host tissue M. chelonae ssp. abscessus, M. kansasii, M. simiae, and M. xenopi have so far almost exclusively been isolated from artificial oligotrophic aquatic habitats, i.e. tap water and drinking water; their natural reservoir is unknown. Some species have not yet been isolated from the environment although epidemiological data suggest that infections caused by these organisms are acquired from environmental sources.

[Legionella in membrane expansion vessels]. / Legionellen in Membran-Druckausdehnungsgefässen.

Membrane expansion vessels (MEV) are installed between cold drinking water supply and hot water system to compensate pressure changes and water losses. An elastic membrane inside the MEV divides a gas pressurized compartment from a water filled compartment, which--in case of flow-through type of MEV--is directly coupled to the water current. While heating the system the expanding water enters the last mentioned compartment. When cooling down, the water is flowing out. Thus MEVs may prevent water losses. Bacteriological investigations of two DEVs of the flow-through type showed the following results: 1. While 5 samples taken from the cold water supply did not yield Legionella, all 7 samples from the outlets of both DEVs tested positive for Legionella (average 21 CFU/ml). 2. In each of 4 samples taken from the outlet of a DEV, total colony counts exceeded the guide value of 100 colonies/ml demanded in the German Drinking Water Act (average 724 colonies/ml at 20 degrees C, 921 colonies/ml at 36 degrees C). 3. Swab and contact culture from one of the membrane indicated excessive surface colonization with Legionella. The findings show the necessity to include MEVs in investigations of hot water systems for Legionella.

Occurrence of mycobacteria in biofilm samples.

The occurrence of mycobacteria was studied in 50 biofilm samples from water treatment plants, domestic water supply systems and aquaria. Mycobacteria were found in 90% of the samples and their densities usually ranged between 10(3) and 10(4) cfu/cm2 (maximum density 5.6 x 10(6) cfu/cm2). Organic substances such as plastics and rubber were usually colonized by larger numbers of mycobacteria than inorganic substances such as copper and glass. The highest mycobacterial densities were found on plastic surfaces which were continuously perfused with water at temperatures between 22 and 30 degrees C. The species identified include Mycobacterium chelonae, M. flavescens, M. fortuitum, M. gordonae, M. kansasii, and M. terrae/nonchromogenicum. The occurrence in microcolonies indicate that biofilms may be an important replication site of aquatic mycobacteria.

Heat susceptibility of aquatic mycobacteria.

An investigation was carried out to measure the heat susceptibility of opportunistic mycobacteria frequently isolated from domestic water supply systems. The study was conducted under standardized conditions designed to resemble those found in oligotrophic aquatic habitats. Strains of the following species were tested: Mycobacterium avium, M. chelonae, M. fortuitum, M. intracellulare, M. kansasii (two strains), M. marinum, M. phlei, M. scrofulaceum, and M. xenopi. Suspensions of the test strains were exposed to temperatures of 50, 55, 60, and 70 degrees C; samples were taken at defined intervals to determine the concentration of survivors. From these data, the decimal reduction times were calculated for each test strain and test temperature. The results indicate that M. kansasii is more susceptible to heat than Legionella pneumophila, whereas the heat susceptibilities of M. fortuitum, M. intracellulare, and M. marinum lie in the same order of magnitude as that of L. pneumophila. The strains of M. avium, M. chelonae, M. phlei, M. scrofulaceum, and M. xenopi were found to be more thermoresistant than L. pneumophila, with the highest resistance being found in M. xenopi. Thermal measures to control L. pneumophila may therefore not be sufficient to control the last five mycobacterial species in contaminated water systems.

Occurrence of mycobacteria in drinking water samples.

33 ground water samples from three drinking water treatment plants and 72 samples from domestic drinking water distribution systems were studied for the occurrence of mycobacteria. 86 out of these samples tested positive for mycobacteria with concentrations generally ranging between 10(2) and 10(3) cfu/l. In one distribution system up to 4.5 x 10(5) cfu/l were found. Species identified by biochemical reactions and by thin layer chromatography of mycolic acids included: Mycobacterium gordonae (most water samples), M. flavescens, M. kansasii, M. chelonae (domestic water systems) and M. fortuitum (drinking water treatment plant). Most isolates did not show patterns of biochemical reactivity attributable to any known mycobacterial species.

[Sanitizing a hospital hot water system contaminated with Legionella pneumophila]. / Sanierung eines mit Legionella pneumophila kontaminierten Krankenhaus-Warmwassersystems.

A number of measures were taken to control Legionella pneumophila in a hospital hot water system over a period of 18 months, including (i) raising the temperature of the water leaving the central storage tanks from initially 55-60 degrees C to approximately 73 degrees C, (ii) heat shock treatment of the whole system with water temperatures above 70 degrees C and (iii) increasing the daily return flow from the hospital circulation system from initially 30 m3 to 120 m3. In addition, (iv) three UV irradiation devices were installed on the inlet and outlets of the storage tanks and (v) an attempt was made to decontaminate the water system by means of CO2. Measures (i) and (iii) were demonstrated to be effective for permanent control of Legionellae in the system. Measures (ii) and (v) proved to have only a short term effect of several days and measure (iv) did not show any effect on the presence of Legionellae at all. The extent of Legionella contamination of the water samples correlated negatively with water temperature and depended on the position of the outlets within the hospital. Different pipe materials (copper, plastics) could not be shown to have any influence on the extent of water contamination with Legionella. The findings of the survey indicate that especially the peripheral areas of the hot water system were colonized by Legionellae.

Mycobacteria in biofilms.

The objective of this study was to elucidate the role of biofilms as the habitat of aquatic mycobacteria. Investigations were carried out on a biofilm which grew on the inner surface of a silicone tube constantly perfused by water of a distribution system known to be contaminated with Mycobacterium kansasii and M. flavescens. The biofilm yielded 2 x 10(5) cfu/cm2 of M. kansasii and 7 x 10(4) cfu/cm2 of M. flavescens after 10 months of perfusion. Microscopic examination revealed that approximately 1/4 to 1/3 of the biofilm organisms visualized by the Ziehl-Neelsen procedure were acid-fast bacteria, most of which occurred in densely packed microcolonies. These findings indicate that biofilms are an important habitat and site for proliferation of aquatic mycobacteria. Biofilms may be an explanation for the problems of controlling mycobacterial contamination of water distribution systems by means of chemical disinfection.

[Visualization of imperceptible blood contamination in operative hospital areas with the help of chemoluminescence]. / Visualisierung nicht erkennbarer Blutkontamination im operativen Krankenhausbereich mit Hilfe der Chemolumineszenz.

Invisible contamination of the skin and other surfaces in the hospital environment with small quantities of blood must be considered a potential source of infection of parenterally transmitted diseases. In the presence of hematin, luminol oxidizes rapidly, emitting visible light in the process. By means of this chemoluminescence reaction, surface contamination with small amounts of blood can be easily visualized. A survey of the hospital environment with this technique revealed that during surgery the extent of blood contamination was much greater than could be judged by the naked eye. Luminol chemoluminescence can be used to spot potential sources of infection of parenterally transmitted diseases and can thus help to reduce their risk of transmission.

[Microbial contamination of water by pipe and tubing material. 2. Growth of Legionella pneumophila]. / Mikrobielle Kontamination von Wasser durch Rohr-und Schlauchmaterialien. 2. Mitteilung: Wachstum von Legionella pneumophila.

In the 1st communication it was possible to show that some hoses and insufficiently cleaned high grade steel pipe can produce a microbial growth. The growth-promoting effect of materials in the water distribution system for Legionella pneumophila has been discussed before. In this investigation it was tested how L. pneumophila behaves in pipes and hoses with narrow diameter, at temperatures from 35 degrees C to 40 degrees C and over a time of half a year. L. pneumophila could be found in high numbers in the water from PVC, PE, PTFE, rubber and silicon hoses all over the time and regularly in low numbers or occasionally in glass, high-grade steel pipes and PA hose. L. pneumophila could be found only for the first 4 weeks in the copper pipe.

[Multiplication and killing temperatures of naturally occurring legionellas]. / Vermehrungs- und Abtötungstemperaturen natürlich vorkommender Legionellen.

Suspensions of legionellae and associated bacteria found in a hot water distribution system were maintained in the exponential phase of growth without addition of nutrients by constant agitation and oxygenation and by periodically transferring them to autoclaved tap water. The suspensions were exposed to different temperatures to determine growth and inactivation kinetics of legionellae kept under conditions similar to their natural environment. Multiplication of the legionellae was found to occur in a temperature range between 20 and 43 degrees C and inactivation was observed above 50 degrees C. Decimal reduction times decreased with increasing temperatures. These findings do not support the hypothesis that naturally occurring legionellae are more heat resistant than strains of the bacterium cultured on artificial media. Frequent failure to eradicate legionellae from hot water systems by elevating the water temperature indicates that it is impossible to achieve effective temperature levels concomitantly in all parts of the system.