Prevention of legionella infections from toilet flushing cisterns

INTRODUCTION

Immunocompromised patients are at an increased risk of severe legionella infections. We present the results of an outbreak investigation initiated following a fatal case of hospital-acquired legionellosis linked to contaminated water from a toilet-flushing cistern. Additionally, we provide experimental data on the growth of Legionella spp. in flushing cisterns and propose a straightforward protocol for prevention.

METHODS

We monitored the growth of Legionella spp. in the building's hot- and cold-water systems using quantitative bacterial culture on selective agar. Molecular typing of Legionella pneumophila isolates from the infected patient and the water system was conducted through core-genome multi-locus sequence typing (cgMLST).

RESULTS

Legionella contamination in the hospital building's cold-water system was significantly higher than in the hot-water system and significantly higher in toilet flushing cistern's water compared with cold water from bathroom sinks and showers. Isolates from the patient and from the flushing cistern of the patient's bathroom were identical by cgMLST. In an experimental setting, daily toilet flushing for a period of 21 days resulted in a 67% reduction in the growth of Legionella spp. in the water of toilet flushing cisterns. Moreover, a one-time disinfection of cisterns with peracetic acid, followed by daily flushing, decreased legionella growth to less than 1% over a period of at least seven weeks in these setting.

CONCLUSIONS

One-time disinfection of highly contaminated cisterns with peracetic acid and daily toilet flushing as short-term measure can significantly reduce legionella contamination in flushing cisterns. These measures may aid in preventing legionella infection among immunocompromised patients.

Das weitgehend unbekannte Krankheitsbild des postoperativen permanenten Hypoparathyreoidismus - Konzeption und Validierung eines innovativen Fragebogenmessinstrumentes

Aim of our study has been the systematic evaluation concerning the still farmost unknown disease of postoperative, permanent hypoparathyroidism. For this we designed a specific questionnaire as measuring instrument--it was evaluated by experts and validated by 3 control groups--to examine then a patient group (n = 20) with symptomatic postoperative, permanent hypoparathyroidism. The application of the questionnaire was very feasible, the reliability of measuring scales according to Cronbach's alpha > or = 0.70. The validity of content and construct validity fully existed (Pearson's correlation coefficient r > or = - 0.27; p < 0,05). The farmost frequent clinical complaints were peripheral cold sensations (65 %), pains in joints (55 %), sensation of heaviness and weakness in extremities (55 %) and paresthesias (45 %). Most frequent clinical symptoms were brittle nails (40 %) and diarrhoea (35 %). Sum and distress level scores for classification of illness severity were determined. In conclusion our questionnaire is a valid instrument and from a clinical point of view easy to apply, reasonable and very feasible in practical use. It represents a novel, optimum instrument to determine disease condition and illness severity of hypoparathyroid patients and makes it possible to gain further information of this up to now less systematically analysed disease.

Methanobacterium thermoautotrophicum encodes two multisubunit membrane-bound [NiFe] hydrogenases. Transcription of the operons and sequence analysis of the deduced proteins

Two gene groups, designated energy converting hydrogenase A (eha) and energy converting hydrogenase B (ehb), each encoding a putative multisubunit membrane-bound [NiFe] hydrogenase, were identified in the genome of Methanobacterium thermoautotrophicum. The length of the transcription units was determined using reverse transcription (RT)-PCR. The eha operon (12.5 kb) and the ehb operon (9.6 kb) were found to be composed of 20 and 17 open reading frames, respectively. Competitive RT-PCR was used to compare the amounts of eha and ehb transcripts with the amounts of transcripts of genes encoding the M. thermoautotrophicum catabolic enzymes cyclohydrolase (mch) and a subunit of heterodisulfide reductase (hdrC). In cells grown under conditions in which H2 was nonlimiting, the eha transcripts were 250-fold and 125-fold less abundant and the ehb transcripts were approximately sixfold and threefold less abundant than the hdrC and mch transcripts, respectively. In cells grown under H2 limitation, the amounts of eha and ehb transcripts were about threefold higher than in cells grown with sufficient H2 when compared to the amounts of hdrC and mch transcripts. Sequence analysis of the deduced proteins indicated that the eha and ehb operons each encode a [NiFe] hydrogenase large subunit, a [NiFe] hydrogenase small subunit, and two conserved integral membrane proteins. These proteins show high sequence similarity to subunits of the Ech hydrogenase from Methanosarcina barkeri, Escherichia coli hydrogenases 3 and 4, and CO-induced hydrogenase from Rhodospirillum rubrum, all of which form a distinct group of multisubunit membrane-bound [NiFe] hydrogenases and show high sequence similarity to the energy-conserving NADH:quinone oxidoreductase (complex I) from various organisms. In addition to these four subunits, the eha operon encodes a 6[4Fe-4S] polyferredoxin, a 10[4F-4S] polyferredoxin, four nonconserved hydrophilic subunits, and 10 nonconserved integral membrane proteins; the ehb operon encodes a 2[4Fe-4S] ferredoxin, a 14[4Fe-4S] polyferredoxin, two nonconserved hydrophilic subunits, and nine nonconserved integral membrane proteins. A function of these putative membrane-bound [NiFe] hydrogenases as proton pumps involved in endergonic reactions, such as the synthesis of formylmethanofuran from CO2, H2 and methanofuran, is discussed.

Two malate dehydrogenases in Methanobacterium thermoautotrophicum

Methanobacterium thermoautotrophicum (strain Marburg) was found to contain two malate dehydrogenases, which were partially purified and characterized. One was specific for NAD+ and catalyzed the dehydrogenation of malate at approximately one-third of the rate of oxalacetate reduction, and the other could equally well use NAD+ and NADP+ as coenzyme and catalyzed essentially only the reduction of oxalacetate. Via the N-terminal amino acid sequences, the encoding genes were identified in the genome of M. thermoautotrophicum (strain DeltaH). Comparison of the deduced amino acid sequences revealed that the two malate dehydrogenases are phylogenetically only distantly related. The NAD+-specific malate dehydrogenase showed high sequence similarity to L-malate dehydrogenase from Methanothermus fervidus, and the NAD(P)+-using malate dehyrogenase showed high sequence similarity to L-lactate dehydrogenase from Thermotoga maritima and L-malate dehydrogenase from Bacillus subtilis. A function of the two malate dehydrogenases in NADPH:NAD+ transhydrogenation is discussed.

Structures and functions of four anabolic 2-oxoacid oxidoreductases in Methanobacterium thermoautotrophicum

Methanobacterium thermoautotrophicum (strain Marburg), which grows autotrophically on H2 and CO2, was found to contain 2-oxoisovalerate oxidoreductase (Vor) and indolepyruvate oxidoreductase (Ior) besides pyruvate oxidoreductase (Por) and 2-oxoglutarate oxidoreductase (Kor). So far, Vor and Ior have only been detected in peptide-utilizing hyperthermophilic Archaea. The four 2-oxoacid oxidoreductases were purified and characterized with respect to their subunit composition, N-terminal amino acid sequences, and catalytic properties. Por and Kor were composed of four different subunits, Vor was composed of three different subunits, and Ior of two different subunits. Comparisons of the N-terminal amino acid sequences revealed that the four enzymes are structurally related to each other and to the respective enzymes from Pyrococcus and Thermococcus sp. Vor from M. thermoautotrophicum differed from Vor from Pyrococcus furiosus in being composed of only three instead of four different subunits. Evidence is presented that in the autotrophic methanogen the four 2-oxoacid oxidoreductases have anabolic functions, Vor and Ior being involved in the biosynthesis of amino acids from fatty acids taken up from the growth medium, as shown by 14C-labelling studies.

[Is involvement of skin appendages or thickness of the epidermis an aid in differential diagnosis between lentigo maligna melanoma and superficially spreading melanoma in situ?]

Neither the involvement of hairfollicles nor of the ducts of the sweat glands by melanoma cells nor the thickness of the epidermis are helpful in differential diagnosis of lentigo maligna melanoma and superficial spreading melanoma in situ. The epidermis was thinner in LMM, however, LLM is mostly localized in the face where the epidermis is thinner than in other areas of the integument.