Theory versus practice, bacteriological efficiency versus personal habits. A bacteriological and user acceptability evaluation of filtering tools for people who inject drugs.

Background

People who inject drugs (PWID) are exposed to associated viral, bacterial and fungal risks. While the international literature mainly focuses on the risk of viral contamination (HIV, HBV and HCV), few have studied risks associated with bacteria and fungi. These risks can be reduced by filtration. Large disparities in the quality of filtration exist between the various available filters. Our research compares both performance and user acceptability of three filters for drug injection (cotton filters, Sterifilt® and wheel filters) by combining epidemiological, sociological and bacteriological analyses.

Methods

A cross-sectional epidemiological study (ANRS-Coquelicot) using Time Location Sampling combined with the Generalized Weight Sampling Method, was conducted among 985 PWID in France. Qualitative interviews were carried out with 38 PWID. Two filtration-based bacteriological studies of 0.20 µm and 0.45 µm wheel filters, Sterifilt® filters, and cotton filters were also conducted. Our multidisciplinary approach enabled us to compare theoretical data on the effectiveness of three types of filters under similar conditions and examine user experience in everyday real-life practice.

Results

The bacteriological study highlighted the value of using wheel filters with a porosity of less than 0.5 µm, as they limit the risk of bacterial and fungal infection. The results of this study clearly highlight a distinction between the efficiency of Sterifilt® and wheel filters, the latter being more effective. Our epidemiological study highlighted that the use of cotton filters is widespread and routine, but is the subject of much criticism among PWID. Sterifilt® is not widely used and its adoption is slow. The wheel filter still remains a largely untested tool, despite its high acceptance among PWID who tested it. Our analysis of epidemiological data combined with the qualitative sociological information collected during our study showed that the criteria for a "good filter", as defined by PWID, were primarily that product loss be prevented and that rapid filtration speed be guaranteed. Particle retention was not considered a priority. The issue of the protecting membrane was not spontaneously mentioned.

Discussion

In our epidemiological and sociological study, the Sterifilt® and wheel filters each received similar evaluations, in terms of PWID perceptions about the difficulties in adopting them into regular practice. Conversely, the results from the bacteriological study clearly showed the greater efficiency wheel filters over Sterifilt®. Low product retention and ease of use are the two most important factors for filters for PWID. Bacterial and fungal risk filtration is considered as less important. It is essential to sensitize PWID about the use of wheel filters, which are of major importance in terms of harm reduction during injection practices. This intervention must be complemented by increased information about all the associated health benefits, and practical recommendations – for example wetting the filter – with the aim of making its use more widespread.