Domestic hot-water boilers harbour active thermophilic bacterial communities distinctly different from those in the cold-water supply

Running cold and hot water in buildings is a widely established commodity. However, interests regarding hygiene and microbiological aspects had so far been focussed on cold water. Little attention has been given to the microbiology of domestic hot-water installations (DHWIs), except for aspects of pathogenic Legionella. World-wide, regulations consider hot (or warm) water as 'heated drinking water' that must comply (cold) drinking water (DW) standards. However, the few reports that exist indicate presence and growth of microbial flora in DHWIs, even when supplied with water with disinfectant residual. Using flow cytometric (FCM) total cell counting (TCC), FCM-fingerprinting, and 16S rRNA-gene-based metagenomic analysis, the characteristics and composition of bacterial communities in cold drinking water (DW) and hot water from associated boilers (operating at 50 - 60 °C) was studied in 14 selected inhouse DW installations located in Switzerland and Austria. A sampling strategy was applied that ensured access to the bulk water phase of both, supplied cold DW and produced hot boiler water. Generally, 1.3- to 8-fold enhanced TCCs were recorded in hot water compared to those in the supplied cold DW. FCM-fingerprints of cold and corresponding hot water from individual buildings indicated different composition of cold- and hot-water microbial floras. Also, hot waters from each of the boilers sampled had its own individual FCM-fingerprint. 16S rRNA-gene-based metagenomic analysis confirmed the marked differences in composition of microbiomes. E.g., in three neighbouring houses supplied from the same public network pipe each hot-water boiler contained its own thermophilic bacterial flora. Generally, bacterial diversity in cold DW was broad, that in hot water was restricted, with mostly thermophilic strains from the families Hydrogenophilaceae, Nitrosomonadaceae and Thermaceae dominating. Batch growth assays, consisting of cold DW heated up to 50 - 60 °C and inoculated with hot water, resulted in immediate cell growth with doubling times between 5 and 10 h. When cold DW was used as an inoculum no significant growth was observed. Even boilers supplied with UVC-treated cold DW contained an actively growing microbial flora, suggesting such hot-water systems as autonomously operating, thermophilic bioreactors. The generation of assimilable organic carbon from dissolved organic carbon due to heating appears to be the driver for growth of thermophilic microbial communities. Our report suggests that a man-made microbial ecosystem, very close to us all and of potential hygienic importance, may have been overlooked so far. Despite consumers having been exposed to microbial hot-water flora for a long time, with no major pathogens so far been associated specifically with hot-water usage (except for Legionella), the role of harmless thermophiles and their interaction with potential human pathogens able to grow at elevated temperatures in DHWIs remains to be investigated.

Introducing bacterial community turnover times to elucidate temporal and spatial hotspots of biological instability in a large Austrian drinking water distribution network

Ensuring biological stability in drinking water distribution systems (DWDSs) is important to reduce the risk of aesthetic, operational and hygienic impairments of the distributed water. Drinking water after treatment often changes in quality during transport due to interactions with pipe-associated biofilms, temperature increases and disinfectant residual decay leading to potential biological instability. To comprehensively assess the potential for biological instability in a large chlorinated DWDS, a tool-box of bacterial biomass and activity parameters was applied, introducing bacterial community turnover times (BaCTT) as a direct, sensitive and easy-to-interpret quantitative parameter based on the combination of 3H-leucine incorporation with bacterial biomass. Using BaCTT, hotspots and periods of bacterial growth and potential biological instability could be identified in the DWDS that is fed by water with high bacterial growth potential. A de-coupling of biomass from activity parameters was observed, suggesting that bacterial biomass parameters depict seasonally fluctuating raw water quality rather than processes related to biological stability of the finished water in the DWDS. BaCTT, on the other hand, were significantly correlated to water age, disinfectant residual, temperature and a seasonal factor, indicating a higher potential of biological instability at more distant sampling sites and later in the year. As demonstrated, BaCTT is suggested as a novel, sensitive and very useful parameter for assessing the biological instability potential. However, additional studies in other DWDSs are needed to investigate the general applicability of BaCTT depending on water source, applied treatment processes, biofilm growth potential on different pipe materials, or size, age and complexity of the DWDS.

Low antimicrobial resistance in Escherichia coli isolates from two large Austrian alpine karstic spring catchments

The increased occurrence of antibiotic resistant bacteria poses a threat to global public health. Clinically relevant resistances also spread through the environment. Aquatic ecosystems in particular represent important dispersal pathways. In the past, pristine water resources have not been a study focus, although ingestion of resistant bacteria through water consumption constitutes a potentially important transmission route. This study assessed the antibiotic resistances in Escherichia coli populations in two large well-protected and well-managed Austrian karstic spring catchments representing essential groundwater resources for water supply. E. coli were detected seasonally only during the summer period. By screening a representative number of 551 E. coli isolates from 13 sites in two catchments, it could be shown that the prevalence of antibiotic resistance in this study area is low. 3.4 % of the isolates showed resistances to one or two antibiotic classes, 0.5 % were resistant to three antibiotic classes. No resistances to critical and last-line antibiotics were detected. By integrating fecal pollution assessment and microbial source tracking, we could infer that ruminants were the main hosts for antibiotic resistant bacteria in the studied catchment areas. A comparison with other studies on antibiotic resistances in karstic or mountainous springs highlighted the low contamination status of the model catchments studied here, most likely due to the high protection and careful management while other, less pristine catchments showed much higher antibiotic resistances. We demonstrate that studying easily accessible karstic springs allows a holistic view on large catchments concerning the extent and origin of fecal pollution as well as antibiotic resistance. This representative monitoring approach is also in line with the proposed update of the EU Groundwater Directive (GWD).

First report on the occurrence of Vibrio cholerae nonO1/nonO139 in natural and artificial lakes and ponds in Serbia: Evidence for a long-distance transfer of strains and the presence of Vibrio paracholerae

Vibrio cholerae are natural inhabitants of specific aquatic environments. Strains not belonging to serogroups O1 and O139 are usually unable to produce cholera toxin and cause cholera. However, non-toxigenic V. cholerae (NTVC) are able to cause a variety of mild-to-severe human infections (via seafood consumption or recreational activities). The number of unreported cases is considered substantial, as NTVC infections are not notifiable and physicians are mostly unaware of this pathogen. In the northern hemisphere, NTVC infections have been reported to increase due to global warming. In Eastern Europe, climatic and geological conditions favour the existence of inland water-bodies harbouring NTVC. We thus investigated the occurrence of NTVC in nine Serbian natural and artificial lakes and ponds, many of them used for fishing and bathing. With the exception of one highly saline lake, all investigated water-bodies harboured NTVC, ranging from 5.4 × 10¹ to 1.86 × 10⁴  CFU and 4.5 × 10² to 5.6 × 10⁶ genomic units per 100 ml. The maximum values observed were in the range of bathing waters in other countries, where infections have been reported. Interestingly, 7 out of 39 fully sequenced presumptive V. cholerae isolates were assigned as V. paracholerae, a recently described sister species of V. cholerae. Some clones and sublineages of both V. cholerae and V. paracholerae were shared by different environments indicating an exchange of strains over long distances. Important pathogenicity factors such as hlyA, toxR, and ompU were present in both species. Seasonal monitoring of ponds/lakes used for recreation in Serbia is thus recommended to be prepared for potential occurrence of infections promoted by climate change-induced rise in water temperatures.

Evidence for a southward autumn migration of nocturnal noctuid moths in central Europe

Insect migrations are spectacular natural events and resemble a remarkable relocation of biomass between two locations in space. Unlike the well-known migrations of daytime flying butterflies, such as the painted lady (Vanessa cardui) or the monarch butterfly (Danaus plexippus), much less widely known are the migrations of nocturnal moths. These migrations - typically involving billions of moths from different taxa - have recently attracted considerable scientific attention. Nocturnal moth migrations have traditionally been investigated by light trapping and by observations in the wild, but in recent times a considerable improvement in our understanding of this phenomenon has come from studying insect orientation behaviour, using vertical-looking radar. In order to establish a new model organism to study compass mechanisms in migratory moths, we tethered each of two species of central European Noctuid moths in a flight simulator to study their flight bearings: the red underwing (Catocala nupta) and the large yellow underwing (Noctua pronuba). Both species had significantly oriented flight bearings under an unobscured view of the clear night sky and in the Earth's natural magnetic field. Red underwings oriented south-southeast, while large yellow underwings oriented southwest, both suggesting a southerly autumn migration towards the Mediterranean. Interestingly, large yellow underwings became disoriented on humid (foggy) nights while red underwings remained oriented. We found no evidence in either species for a time-independent sky compass mechanism as previously suggested for the large yellow underwing.

Effects of monthly intramuscular neridronate in rheumatic patients in chronic treatment with low-dose glucocorticoids

OBJECTIVES

To assess the effects of intramuscular (im) neridronate (NE) on lumbar and femoral neck BMD and on markers of bone turnover in rheumatic patients under chronic low-dose glucocorticoids (GC) therapy.

METHODS

Sixty-nine osteopoenic and osteoporotic patients, affected by rheumatic diseases and gastric or esophageal conditions which contraindicated treatment with oral bisphosphonates (BPs), were randomly assigned to: Group A (23 patients) administered with daily calcium 1 g and vitamin D 800 UI; Group B (46 patients) receiving daily calcium 1 g, vitamin D 800 UI and im NE 25 mg monthly.

RESULTS

After 12 months of therapy (M12) lumbar BMD was reduced of 2.97% in Group A, and improved of 3.34% (p=0.001) in Group B; at M12, femoral neck BMD was reduced of 2.40% in Group A and improved of 1.78% in Group B (p=0.010). After 6 (M6) and 12 months of therapy, the bone resorption markers were significantly reduced in Group B: OHPr-41.64% at M6 (p<0.001) and -37.91% at M12 (p<0.001); DPD-33.4% at M6 (p<0.001) and -33.18% (p<0.001) at M12: NTX -57.08% (p<0.001) at M6 and -55.95% (p<0.001) at M12; OC-11.62% (p=0.05) at M6 and -12.62% at M12 (p=0.06); B-ALP -13.95 % at M6 (p=0.04) and -0.85% at M12 (NS).

CONCLUSION

A twelve-month intramuscular NE treatment in rheumatic patients under GCs therapy improves lumbar and femoral BMD and mainly reduces the markers of bone resorption.

Compared clinical efficacy and bone metabolic effects of low-dose deflazacort and methyl prednisolone in male inflammatory arthropathies: a 12-month open randomized pilot study

OBJECTIVE

To evaluate: (i) a correct equivalence ratio of clinical efficacy between low-dose deflazacort (DFZ) and methyl prednisolone (MP); and (ii) bone metabolic effects of low-dose DFZ and MP in the treatment of male RA and PsA.

METHODS

A total of 21 male patients with active RA or PsA, naive to steroid treatment were chosen for the study. Group I: 10 patients treated for 6 months with DFZ 7.5 mg, calcium, cholecalciferol and a DMARD; for the following 6 months with MP 4 mg, calcium, cholecalciferol and a DMARD. Group II: 11 patients treated for 6 months with MP 4 mg, calcium, cholecalciferol and a DMARD; for the following 6 months with DFZ 7.5 mg, calcium, cholecalciferol and a DMARD. At day 0, 90, 180, 240 and 360 evaluation of ACR improvement criteria; a blood sample for total and bone-specific ALP, calcium, phosphorus, PTH, SHBG, estradiol, ACTH, osteocalcin, LH, OPG; a sample of urine for calcium, phosphorus, creatinine and DPD.

RESULTS

13/21 patients (6/10 Group I; 7/11 Group II) reached ACR 20 at 6 months; 14/21 (7/10 Group I, 7/10 Group II) at 12 months. Only at the third month we observed in Group II vs Group I a reduction of OPG (24% vs 6%, P = n.s.); ALP (P < 0.001) and osteocalcin (P = 0.006) decreased in both groups from the third month; DPD decreased in both groups only from the sixth month (P = 0.002).

CONCLUSIONS

The correct equivalence ratio of DFZ to MP is 1.875:1, and of DFZ to prednisolone 1.5:1. We found a relative prevalence of bone resorption compared to bone formation in the first 6 months of treatment. The trend of OPG requires further investigation.

Clarithromycin in rheumatoid arthritis patients not responsive to disease-modifying antirheumatic drugs: an open, uncontrolled pilot study

OBJECTIVE

In 1996 we found by serendipity that 2 patients with rheumatoid arthritis (RA) who were taking clarithromycin (CM) to eradicate Helicobacter pylori experienced a regression of their RA symptoms. Following this observation, we tested the hypothesis that this reduction in symptoms could have been caused by CM administration.

METHODS

We performed a 6-month, open, uncontrolled pilot study on 18 patients (14 females and 4 males, mean age 62 yrs.) with RA who had previously received DMARDs (mean 2.6) and discontinued the treatment at least one month earlier because lack of efficacy or severe side effects. Patients were treated with CM at the dose of 500 mg twice per day for the first 10 days, followed by a daily maintenance dose of 250 mg twice per day.

RESULTS

4/18 patients did not complete the treatment, 2/18 were not responsive to the treatment and 2/18 discontinued the treatment. Following ACR criteria the improvement was: 10 patients ACR 20; 6 patients ACR 50; and 2 patients ACR 70. The remaining 4 patients did not reach ACR 20 since either the number of tender or swollen joints was not to the level required. Reductions in PGE2 and soluble phospholipase A2 plasma levels were closely related to CM plasma levels.

CONCLUSIONS

Ourfindings suggest that CM treatment can be beneficial in those patients who are not responsive to or cannot tolerate DMARDs. No definitive conclusions can be drawn based on the present study, due to the small sample size involved.