Bacillus cereus biofilm formation on central venous catheters of hospitalised cardiac patients

Abstract

Formation of bacterial biofilms is a risk with many in situ medical devices. Biofilm-forming Bacillus species are associated with potentially life-threatening catheter-related blood stream infections in immunocompromised patients. Here, bacteria were isolated from biofilm-like structures within the lumen of central venous catheters (CVCs) from two patients admitted to cardiac hospital wards. Isolates belonged to the Bacillus cereus group, exhibited strong biofilm formation propensity, and mapped phylogenetically close to the B. cereus emetic cluster. Together, whole genome sequencing and quantitative PCR confirmed that the isolates constituted the same strain and possessed a range of genes important for and up-regulated during biofilm formation. Antimicrobial susceptibility testing demonstrated resistance to trimethoprim-sulphamethoxazole, clindamycin, penicillin and ampicillin. Inspection of the genome revealed several chromosomal β-lactamase genes and a sulphonamide resistant variant of folP. This study clearly shows that B. cereus persisting in hospital ward environments may constitute a risk factor from repeated contamination of CVCs.

Keywords:

• Biofilm
• central venous catheters
• cardiac patients
• Bacillus cereus group
• whole genome sequencing
• comparative genomics

Acknowledgements

The authors thank Ewa Jaroszewicz and Beata Urbanczyk Mohebi for excellent experimental assistance. The sequencing service was provided by the Norwegian Sequencing Centre (www.sequencing.uio.no), a national technology platform hosted by the University of Oslo and supported by the ‘Functional Genomics’ and ‘Infrastructure’ programmes of the Research Council of Norway and the Southeastern Regional Health Authorities.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

This work was supported through a grant to SI from the Higher Education Commission of Pakistan under the International Research Support Initiative Programme (reference number no. 1-8/HEC/HRD/2017/6878). AH, SF and OAØ were supported by the Centre for Integrative Microbial Evolution and the School of Pharmacy, Faculty of Mathematics and Natural Sciences, University of Oslo.