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Open Access Highly Accessed Research article

Microbiological pattern of arterial catheters in the intensive care unit

Li Zhang1*, Kadaba S Sriprakash2, David McMillan3, John R Gowardman4, Bharat Patel5 and Claire M Rickard6

Author Affiliations

1 Research Centre for Clinical and Community Practice Innovation, Griffith University, Brisbane QLD 4111, Australia

2 Bacterial Pathogenesis Laboratory, Queensland Institute of Medical Research, Herston, QLD 4006, Australia

3 Bacterial Pathogenesis Laboratory, Queensland Institute of Medical Research, Herston, QLD 4006, Australia Griffith Medical Research College, a joint program of Griffith University and the Queensland Institute of Medical Research, QIMR, Herston, QLD 4006, Australia

4 Department of Intensive Care Medicine, Royal Brisbane Women's Hospital, Herston, QLD 4029, Australia Research Centre for Clinical and Community Practice Innovation, Griffith University, Brisbane QLD 4111, Australia

5 School of Biomolecular and Physical Sciences, Griffith University, Brisbane, QLD 4111, Australia

6 Research Centre for Clinical and Community Practice Innovation, Griffith University, Brisbane QLD 4111, Australia

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BMC Microbiology 2010, 10:266  doi:10.1186/1471-2180-10-266

Published: 19 October 2010

Abstract

Background

Intravascular catheter related infection (CRI) is one of the most serious nosocomial infections. Diagnostic criteria include a positive culture from the catheter tip along with blood, yet in many patients with signs of infection, current culture techniques fail to identify pathogens on catheter segments. We hypothesised that a molecular examination of the bacterial community on short term arterial catheters (ACs) would improve our understanding of the variety of organisms that are present in this niche environment and would help develop new methods for the diagnosis of CRI.

Results

The whole bacterial community presenting on all ACs was evaluated by molecular methods, i.e., a strategy of whole community DNA extraction, PCR amplification followed by cloning and 16S rDNA sequence analysis. Ten ACs were removed from patients suspected of CRI and 430 clones from 5 "colonised" and 5 "uncolonised" (semi-quantitative method) AC libraries were selected for sequencing and subsequent analysis. A total of 79 operational taxonomic units (OTUs) were identified at the level of 97% similarity belonging to six bacterial divisions. An average of 20 OTUs were present in each AC, irrespective of colonisation status. Conventional culture failed to reveal the majority of these bacteria.

Conclusions

There was no significant difference in the bacterial diversity between the 'uncolonised' and 'colonised' ACs. This suggests that vascular devices cultured conventionally and reported as non infective may at times potentially be a significant source of sepsis in critically ill patients. Alternative methods may be required for the accurate diagnosis of CRI in critically ill patients.