PWID; Longitudinal S Aureus Colonization Pattern and the Impact on Infection Frequency by Regular Showers With Chlorhexidine

Overview

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.