The distribution of ureC was investigated among 294 Escherichia coli isolates, comprising 72 strains from the E. coli standard reference collection (ECOR), 62 strains from the diarrhoeagenic E. coli (DEC) collection, and 160 clinical isolates of Shiga toxin-producing E. coli (STEC). The ureC gene was more frequent among STEC isolates harbouring eae than among those lacking eae (p < 0.0001). All clinical STEC isolates of serogroups O111 and O145 contained ureC, but only two of 294 isolates expressed urease activity. The silencing of urease expression could not be linked to a stop codon in ureD. The frequent occurrence of ure genes in eae-positive STEC isolates makes them valuable markers for virulence.

Enterohemorrhagic Escherichia coli (EHEC) O157 strains belong to two closely related major groups, which are differentiated by their sorbitol fermentation phenotypes. Here we studied the conservation of urease genes and their expression in sorbitol-fermenting (SF) and non-SF EHEC O157 isolates. PCR targeting ure genes (ureA, -B, -C, -D, -E, -F, and -G) demonstrated that each of these genes was present in 58 of 59 EHEC O157:H7 isolates. In contrast, none of 82 SF EHEC O157:NM (nonmotile) isolates contained any of the ure genes. Hence, the absence of the urease genes distinguishes SF EHEC O157:NM strains from EHEC O157:H7, but this absence demonstrates that the urease genes are not useful genetic targets for the detection of EHEC strains, because SF EHEC O157:NM strains are missed by such a strategy. When examined for urease activity on Christensen agar and in the API 20E system, only one O157:H7 strain displayed urease activity and produced elevated levels of ammonia, which was subsequently confirmed by ammonia electrode measurement. Because the ure genes were absent from each of nine strains of E. coli O55:H7, the proposed progenitor of EHEC O157, we hypothesize that EHEC O157:H7 diverged from the evolutionary pathway at an early stage and then acquired the O islands carrying the ure gene cluster.

ABSTRACT A total of 66 (98.5%) of 67 enterohemorrhagic Escherichia coli (EHEC) O157:H7 strains had increased potassium tellurite (Te) MICs (32 to 1,024 μg/ml), grew on Te-containing media, and possessed Te resistance ( ter ) genes, whereas 83 (96.5%) of 86 sorbitol-fermenting (SF) EHEC O157:NM strains had Te MICs of ≤4 μg/ml, did not grow on Te-containing media, and lacked ter genes. Optimal detection of SF EHEC O157:NM strains requires Te-independent strategies.

The aim of the present research project was to investigate and evaluate technical and organisational measures targeted at bioaerosol reduction during the refuse collection and to determine the exposure of refuse collectors to dust, fungi and endotoxins in an on-the-job situation with different vehicle technologies and states of hygiene. The following technical factors were found to influence the bioaerosol concentration at the refuse collector's workplace: compaction method, lifting device control, rave rail height, hopper depth, design of intake area and dust interception. For instance, notably higher total fungal counts were recorded with rotating drum compaction than with packer plate compaction. A hinged lid closure at the lifting device in conjunction with a suction unit induced a positive effect. In addition, the automatic lifting system had a positive influence on rear-end loaders, as did loading operation control from the closed driver's cab on side loaders. Regular internal and external high-pressure cleaning of the lifting device at intervals of not more than 14 days is recommended as a basic rule for vehicle hygiene.

Die Einführung der getrennten Erfassung und Bewertung von Wertstoffen des Hausmülls hat auch Auswirkungen auf die Arbeitsbedingungen in der Abfallwirtschaft, wobei ein Aspekt die Bioaerosolexposition der Arbeitnehmer darstellt. In der vorgelegten Studie stand die Belastung der Beschäftigten im Bereich der Abfallwirtschaft im Vordergrund. Es wurde die Exposition von Müllwerkern gegen Pilze, Bakterien und Endotoxine beim realen Arbeitsvorgang sowie der Gesundheitszustand von insgesamt 220 Müllwerkern durch arbeitsmedizinische Untersuchungen im Zusammenhang mit der Keimexposition überprüft. Nicht-invasive Methoden wie die Gewinnung von Nasallavage (NAL) und induziertem Sputum wurden durchgeführt und darin zelluläre Parameter und lösliche Entzündungsmediatoren bestimmt. Tendenziell zeigte sich in der Gruppe der Bioabfall-exponierten Beschäftigten (n=108) eine höhere Gesamtzellzahl in den NAL-Proben als unter den Beschäftigten ohne Bioabfallexposition (n=103). Nur in wenigen Fällen konnten eosinophile Granulozyten differentialzytologisch nachgewiesen werden, wogegen neutrophile Granulozyten in 80% der untersuchten NAL-Proben – allerdings auch ohne gruppenspezifische Unterschiede – detektiert werden konnten. Ebenso ergaben sich für die Parameter Albumin, ECP, NO keine gruppenspezifischen Unterschiede. Die IL-8-Konzentrationen in den NAL- und Sputumproben der zwei Kollektive waren im Mittel unterschiedlich, wobei jeweils in den Proben des Kollektivs mit Bioabfallexposition höhere Konzentrationen vorlagen als im Kollektiv ohne Bioabfallexposition und im Kontrollkollektiv (n=12) (Jonckheere-Terpstra-Test p<0,01). IL-8-Konzentrationen sowohl in NAL- als auch in Sputumproben scheinen daher sinnvolle Parameter darzustellen, eine ansonsten nur sehr ungenaue Abschätzung der Keimbelastung zu ermöglichen und sollten in zukünftigen Studien in den genannten Proben, die unter wenig invasiven und für den Probanden kaum belastenden Bedingungen zu gewinnen sind, als Parameter einer internen Belastungsmessung weiter validiert werden.

This chapter evaluates the efficacy of copper-silver ionization that is reported to be a useful tool to control growth of Legionella. Copper-silver ionization was tested over a period of 1 year as the first step in a multiple-barrier system controlling Legionella. In Germany, additions of silver and copper to drinking water need special approval of the Ministry of Health and are permitted only with substantial restrictions. Measurable effects in Legionella reduction can be achieved only at silver concentrations significantly exceeding the German standard of 10 μg/liter. Copper values exceeded national standards, preventing a short-term high dosing of silver. Concentrations of both metals vary depending on water flow. Silver cannot be analyzed directly with in the system, causing a considerable feedback delay. Legionella counts stayed above targeted values (working standard, Legionella counts <1 CFU/ml) . Reduction is not as efficacious as in hot water systems maintaining about 60№C. Long-term effects (e.g., development of heavy-metal resistance) of adding silver and copper are yet to be evaluated.

To determine the bioaerosol exposure of refuse collectors, field measurements were performed under real working conditions within the framework of a research project. Influencing variables such as different types of refuse, community structure, collection interval and season were taken into account. Overall, 1612 samples were taken in towns of Westfalia, Germany. With workplace levels on a scale of 103 to less than 104 CFU/m3 for the loader, the results show a surprisingly low total fungi concentration in comparison with earlier studies. Total bacteria concentrations, in contrast, were largely on a scale of 104 CFU/m3, with 105 CFU/m3 being registered sporadically, especially in apartment-block districts. Endotoxin levels were high especially in the summer months, occasionally reaching values of more than 50 EU/m3, whereas they were normally below 10 EU/m3 in autumn and winter. Inside the cab, the exposure level for the entire spectrum was at least one power of ten lower. The factors believed to account primarily for the low total fungi concentration were workplace hygiene, the prevailing 1-week collection interval, and the low in-process exposure time resulting from the effective deployment of automatic lifting devices. In contrast, the type of refuse was not found to have a significant influence.

In a current study funded by the Federal Institute of Occupational Safety and Hygiene the microbial exposure during waste collection and the health of waste collectors are being examined. The investigation of the exposure is carried out in standard experiments and in field studies. It should give information about the extent of emissions of bacteria and fungi spores und confounding factors. Medical examinations of waste collectors will show if there are special health risks attributable to waste collection.

Appearance of Legionella disease generally is underrated. Conclusions as to disease frequency from Legionella antibody investigations are not reliable. The number of microbes necessary to produce illness depends from individual preliminary conditions. In special areas of the hospital the rate of diseases caused by Legionella can be reduced by protection. In bathing areas generally the hitherto existing regulations of the Federal Health Authority are sufficient: Continual warm water temperature increases from 60 degrees C, chlorination if necessary, regular stepwise controls. Insufficient results are produced by intermittent temperature increases. Filters that are impermeable for microbes appear uneconomical for bathing areas.

Legionella inevitably are imported from natural reservoirs into drinking-water supplies. Bacterial growth predominantly occurs at water temperatures between 40 degrees C und 50 degrees C (104 degrees F and 122 degrees F). Heat conduction to insufficiently insulated cold water tubes implies the possibility of increased contamination also there. Problems with contamination arise in parts of the water supplies with stagnant warm water. Therefore, reservoirs should be descaled regularly. In general, for prophylaxis are recommended raising the temperature of warm water to 60 degrees C (140 degrees F), regular microbiological control of water quality and regular technical maintenance of waterworks where warm water stagnates for some time. Patients bearing a higher risk of Legionella-infections require intensified precautionary measures. The diagnosis of legionellosis should be based on the direct evidence of immunofluorescence-stained microorganisms. Finding increased antibody titers alone is not always correlated with the response to Legionella-specific therapy.

For the outbreak of diseases caused by Legionellae an infection by contaminated water is thought to be responsible. In the environment of patients with a high risk of infection (e. g. after kidney transplantation, immunosuppression) prophylactic measures (rising the temperature of the warm water to 60 °C) should be combined with bacteriological controls. It has to be taken into account, however, that only by taking a couple of samples from the same outlet during a period of time a colonization of central installation systems (sediments, storage tanks) can be discovered. In patients with acute pneumonia of unknown origin serological tests of Legionella antibodies are not very specific. Antibody titers of not infected and with Legionella infected patients show no significant difference. Well suited for the diagnosis of a legionellosis is the use of the Direct Immunofluorescent Antibody Assay (DFA) in invasively sampled specimens. In immunocompromised pneumonia patients 18.3% of bronchoalveolar lavages and 16.0% of bronchoalveolar aspirates are Legionella positive.