Summary of the second meeting of the International Forum on Water Hygiene in Buildings (IFOWAHB) from 01 to 02.06.2007 in Stockholm

Development of a tool to assess evidence for causality in studies implicating sink drains as a reservoir for hospital-acquired gammaproteobacterial infection

BACKGROUND

Decades of studies document an association between Gammaproteobacteria in sink drains and hospital-acquired infections, but the evidence for causality is unclear.

AIM

We aimed to develop a tool to assess the quality of evidence for causality in research studies that implicate sink drains as reservoirs for hospital-acquired Gammaproteobacterial infections.

METHODS

We used a modified Delphi process with recruited experts in hospital epidemiology to develop this tool from a pre-existing causal assessment application.

FINDINGS

Through four rounds of feedback and revision we developed the 'Modified CADDIS Tool for Causality Assessment of Sink Drains as a Reservoir for Hospital-Acquired Gammaproteobacterial Infection or Colonization'. In tests of tool application to published literature during development, mean percent agreement ranged from 46.7% to 87.5%, and the Gwet's AC1 statistic (adjusting for chance agreement) ranged from 0.13 to 1.0 (median 68.1). Areas of disagreement were felt to result from lack of a priori knowledge of causal pathways from sink drains to patients and uncertain influence of co-interventions to prevent organism acquisition. Modifications were made until consensus was achieved that further iterations would not improve the tool. When the tool was applied to 44 articles by two independent reviewers in an ongoing systematic review, percent agreement ranged from 93% to 98%, and the Gwet's AC1 statistic was 0.91-0.97.

CONCLUSION

The modified causality tool was useful for evaluating studies that implicate sink drains as reservoirs for hospital-acquired infections and may help guide the conduct and reporting of future research.

Distribution of Legionella pneumophila bacteria and Naegleria and Hartmannella amoebae in thermal saline baths used in balneotherapy

The present study was aimed at investigating the coexistence and interactions between free living amoebae of Naegleria and Hartmannella genera and pathogenic Legionella pneumophila bacteria in thermal saline baths used in balneotherapy in central Poland. Water samples were collected from November 2010 to May 2011 at intervals longer than 1 month. The microorganisms were detected with the use of a very sensitive fluorescence in situ hybridisation method. In addition, the morphology of the amoebae was studied. Despite relatively high salinity level, ranging from 1.5 to 5.0 %, L. pneumophila were found in all investigated baths, although their number never exceeded 10⁶ cells dm⁻³. Hartmannella were not detected, while Naegleria fowleri were found in one bath. The observation that N. fowleri and L. pneumophila may coexist in thermal saline baths is the first observation emphasising potential threat from these microorganisms in balneotherapy.