Question 23.1

A 55-year-old obese male with dysuria and hypotension was admitted to the ICU 12 hours previously. He had a femoral central venous catheter inserted in the Emergency Department on admission. Your registrar has reported that blood cultures collected through the CVC at the time of insertion growing Staphylococcus epidermidis.

What advice will you give the registrar regarding the blood culture result?
List two groups of patients in whom this result would be a concern.

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College Answer

Not to give additional antibiotics

Consider removing / re-siting the femoral CVC depending on the patient’s condition

1. Immunocompromised patients with intravascular devices
2. Patients with surgical implants
3. Patients high risk for endocarditis
4. Low weight neonates and elderly

Discussion

Key points about the first part of this question:

Coagulase-negative staph bacteraemia might sound quite rare (7 per 10,000 admissions) but is in fact the most common catheter-related bacteraemia.
Cultures collected during CVC insertion are more likely to yield contaminants than peripheral blood cultures
Significance of a coagulase-negative staph in a blood culture is determined by the presence of the clinical features of infection and in those cases one would be obliged to change the line. If it was a true bacteraemia, it will occur again in 20% of patients in whom the catheters remain in situ, compared to 3% in patients whose lines are changed.

Key points about the risk factors for clinically significant S.epidermidis bacteraemia:

Anyone at risk of native valve endocarditis
Anyone with artifical valves
Anyone with a history of rheumatic heart disease
Anyone who is immunosuppressed
Anyone with an implated pacemaker, or any other surgical implant
Any low birth infant
Any elderly person (>65 years of age)

In any case, the question clearly points our way to urosepsis. The guy had dysuria, which is not usually a feature of staphylococcal endocarditis so severe that it would cause haemodynamic collapse and ICU admission.

References

De Leon, Samuel Ponce, and Richard P. Wenzel. "Hospital-acquired bloodstream infections with Staphylococcus epidermidis: review of 100 cases."The American journal of medicine 77.4 (1984): 639-644.

Haslett, T. M., et al. "Microbiology of indwelling central intravascular catheters."Journal of clinical microbiology 26.4 (1988): 696-701.

Stohl, Sheldon, et al. "Blood cultures at central line insertion in the intensive care unit: comparison with peripheral venipuncture." Journal of clinical microbiology 49.7 (2011): 2398-2403.

Beekmann, Susan E., Daniel J. Diekema, and Gary V. Doern. "Determining the clinical significance of coagulase-negative staphylococci isolated from blood cultures." Infection control and hospital epidemiology 26.6 (2005): 559-566.

Raad, Issam, et al. "Impact of central venous catheter removal on the recurrence of catheter-related coagulase-negative staphylococcal bacteremia."Infection control and hospital epidemiology (1992): 215-221.

Raad, Issam, et al. "Management of the catheter in documented catheter-related coagulase-negative staphylococcal bacteremia: remove or retain?."Clinical infectious diseases 49.8 (2009): 1187-94.

Chu, Vivian H., et al. "Emergence of coagulase-negative staphylococci as a cause of native valve endocarditis." Clinical infectious diseases 46.2 (2008): 232-242.

Blot, François, et al. "Earlier positivity of central-venous-versus peripheral-blood cultures is highly predictive of catheter-related sepsis." Journal of clinical microbiology 36.1 (1998): 105-109.

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