Clinical Trial Summary
People who inject drugs (PWID) have increased risk of Staphylococcus aureus (S. aureus)
colonization, skin and soft tissue infections (SSTI), and systemic infections like
septicaemia and endocarditis. International research and data from Malmö needle exchange
program (NEP) show a 60 - 70% lifetime SSTI prevalence. Longitudinal colonization pattern of
S. aureus and its association with infection frequency among PWID is unknown. Cultures from
the anterior nares, throat and perineum are used to indirectly assess S. aureus skin
colonization. In PWID 28 - 45% are colonized in the nares, which increases risk of
infections. Clinical significance of extra-nasal colonization, and persistent/intermittent
colonization is uncertain.
The S. aureus genome can be characterized by whole genome sequencing (WGS). Certain types are
associated with abscesses and systemic infections. The infection pattern among PWID is
unknown.
S. aureus skin colonization level is decreased by chlorhexidine body wash and nasal mupirocin
used as surgical prophylaxis and treatment of furunculosis. To our knowledge, disinfection
effect on infections in PWID is not studied. However, the clinical impression is that severe
infections have somewhat diminished since the NEP started distributing skin disinfectant
tissues.
RESEARCH QUESTIONS
1. Can repeated skin wash with chlorhexidine decrease infection frequency among PWID?
2. Is the longitudinal S. aureus colonization pattern associated with infection prevalence
among PWID?
3. Can the risk of S. aureus-infections be predicted by quantification of bacterial level
in anterior nares, throat, perineum or skin lesions/eczema?
4. Can different types of S. aureus be identified, that are associated with colonization or
infection among PWID (by WGS)?
METHODS AND TIME PHRAME Malmö NEP was established in 1986, and several studies assessing HIV,
hepatitis and sociological questions have been conducted in this setting. In December 2016
continuous inclusion of 100 PWID for the actual study started at Malmö NEP. The study period
is estimated to two years, with scientific papers expected for publication.
During the first year of the study, mapping of S. aureus colonization pattern among all study
participants is conducted by repeated sampling, clinical evaluation of eczemas, and
interviews regarding infections. Every third month samples are collected from nares, throat,
perineum and skin lesions. Semi quantification of S. aureus takes place at the
microbiological research laboratory at Lund University. BBL CHROMagar Staph aureus-plates are
used and incubated in 35oC air for 48h. S. aureus-colonies are identified and quantified
manually by pink colour change and Pastorex. MALDI-TOF will be used in unclear cases.
Disk-diffusion will be used for resistance determination. Bacterial isolates will be frozen
to -70oC for later WGS.
Intervention with chlorhexidine wash starts one year after inclusion for each study subject,
and will continue for one additional year. Study participants with S aureus colonization will
undergo regular showers with chlorhexidine (intervention group) at the needle exchange. In
order to avoid bacterial resistance, muporicin will not be used. During the intervention,
cultures, interviews and clinical evaluation will continue.
