A 69-year-old man with a history of diabetes mellitus, hypertension, coronary artery disease, and ventricular arrhythmias was admitted after a witnessed collapse at home. The patient underwent cardiac resuscitation and intubation by emergency medical services (EMS); upon admission he was found to have an inferior wall myocardial infarction. There was also some concern that the patient had seizure activity noted upon arrival in the emergency department. He underwent cardiac catheterization and was found to have diffuse three-vessel disease, with a 90% occlusion in the postero-lateral (PL) segment of the right coronary artery (RCA). He underwent successful coronary angioplasty of the RCA lesion and was transferred to the intensive care unit (ICU) for further monitoring. A right internal jugular central venous catheter (CVC) and right radial arterial line were placed on hospital day 2. On hospital day 5 the patient was noted to have fever, with his temperature measured as high as 39.3°C (102.7°F), and tachycardia. He remained normotensive. Cultures were obtained, including two sets of blood cultures drawn within 10 minutes of each other. One set of blood cultures was drawn peripherally, and one set was drawn through the CVC. Broad-spectrum antibiotics, including vancomycin and cefepime, were started empirically. Within 6 hours, the microbiology lab reported positive growth from one of the two bottles that was drawn via the CVC.
Given this clinical scenario, how would you go about diagnosing catheter-related bloodstream infection (CRBSI)?
Positive microbiologic results of paired blood cultures drawn from the CVC and peripheral vein support the diagnosis of CRBSI, with particular emphasis on the differential time to positivity. CVC catheter tip cultures showing the same organism as found in the blood are also useful in identifying the line as the source of bloodstream infection.1
The differential diagnosis for infections causing fever in the ICU setting is broad, and CRBSIs are the third most common infection diagnosed in the ICU, following pneumonia and sinusitis.2 About 5% of patients with central venous catheters develop CRBSIs, and the incidence increases with the duration of catheter use and number of lumens.
Diagnosis of CRBSI includes both examination of the catheter site, looking for overt signs of infection such as purulence, erythema, or tenderness, and the use of blood cultures.3 Blood cultures must always be obtained before initiating antimicrobial therapy, one set from the catheter and one from a peripheral vein. The blood culture sets must be labeled with the source and time to assist in diagnosis. In CRBSI, the cultures drawn from the catheter will often become positive before the peripheral blood culture, reflecting the higher burden of organisms on the catheter.4
If there are signs of infection at the catheter insertion site or tenderness over the subcutaneous portion of the catheter, the catheter must be removed and the catheter tip submitted for quantitative culture. Positive catheter tip cultures are ...