Similar intraoperative microbiomes in de novo and replacement cardiac implantable electronic device pockets support transient contamination over stable colonisation.

BACKGROUND

The source of bacteria detected in cardiac implantable electronic device (CIED) pockets-whether true colonisation or intraoperative contamination-has significant implications for infection prevention strategies.

AIM: To compare intraoperative microbial dynamics during de novo pacemaker implantation versus generator replacement using 16S rRNA gene sequencing.

METHODS

In this prospective study, samples were collected from 18 asymptomatic patients (11 new implants, seven replacements) at three timepoints: skin before incision (T1), pocket after creation (T2), and pocket before closure (T3). Microbiome analysis was performed via 16S rRNA gene sequencing of the V3-V4 region. α-diversity (Simpson index) and β-diversity (Bray-Curtis dissimilarity) were analysed.

FINDINGS: Microbial community composition and relative abundance were similar between groups at all timepoints. Predominant genera included Achromobacter, Pedobacter, Pseudomonas, Acinetobacter, Blastococcus, and Paracoccus. No significant differences in α- or β-diversity were found between new and replacement groups at T2 and T3. The only significant difference was a higher α-diversity at T1 (skin) in the new implantation group (P = 0.037), likely reflecting age-related skin flora differences. No patient developed a clinical infection during follow-up (mean 9.4 ± 1.8 months).

CONCLUSION

The absence of distinct microbial signatures in replacement pockets and the prevalence of environmental bacteria strongly suggest that detected microorganisms originate from intraoperative contamination. This underscores the paramount importance of rigorous aseptic technique over surveillance for colonization in preventing CIED infections.