Many microorganisms cause catheter-related infections, most commonly Staphylococcus aureus, coagulase-negative staphylococci, Enterococcus, and Candida (Table 121-1).Gram-positive cocci, primarily staphylococci, cause more than 50% of central venous catheter associated bacteremias and exit site infections. Other skin flora, diphtheroids, and Bacillus are often involved. Gram-negative organisms cause 25% to 40% of infections. Polymicrobial infections of central venous catheters are common. Fungal catheter infections, usually Candida albicans, are most common among persons receiving broad-spectrum antibiotics or parenteral nutrition.
The rates of bloodstream infection of peripheral venous catheters are from 0 to 2 per 1000 catheter-days and for central catheters from less than 2 to 30 per 1000 catheter-days. Risk factors for infection include prematurity, burns and skin disorders that adversely affect the skin integrity, neutropenia, and
Chapter 121 u Infections Associated with Medical Devices 395
Tunneled? Tunneled? Hemodynamically unstable or no improvement after 72 hours persistently positive culture or endocarditis/ thrombophlebitis or pocket infection cellulitis AND: NOT TERMINALLY ILL LINE NEEDED? YES1 line >1 line Antibiotic through all lumina consider thrombolytic agents YES NO NO YES NO YES NO NO Insertion easy? REMOVE  THE LINE YES
Figure 121-1 Management of central venous catheter infection.
(From De Paw BE, Verweij PE: Infections in patients with hematologic malignancies. In Mandell GL, Bennett JE, Dolin R, editors: Principles and Practice of Infectious Diseases, ed 6, Philadelphia, 2005, Churchill Livingstone, Fig. 307-1, p 3434.) other immunodeficiencies (see Chapter 120). Infection rates are lower for tunneled and implanted catheters. Catheters inserted in emergency settings are more likely to be infected than catheters placed electively.
Clinical signs of catheter-associated bacteremia or fungemia range from mild fever to overwhelming sepsis. Infection at the site of the central catheter entrance is manifested as a localized cellulitis with warmth, tenderness, swelling, erythema, and discharge. Tunnel infection is manifested by similar findings along the tunnel route. Peripheral phlebitis or catheter-related infection is classically manifested as a warm, erythematous, tender palpable cord originating at the IV catheter site but may be subclinical or manifested only by fever without signs of local inflammation.
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The treatment of catheter-related infection depends on the site of the infection and the pathogen involved. Catheters that are no longer necessary should be removed if infection is suspected. Catheter-associated bacteremia can be treated with simple catheter removal, removal plus antibiotics, or, in a stable patient, an attempt of antibiotic therapy alone (Fig. 1211). Infection with organisms of low virulence may be manifested by fever alone, and removal of the catheter frequently is followed by prompt defervescence and complete resolution of infection. Empirical initial therapy for suspected infection should include antibiotics active against gram-negative organisms such as a broad-spectrum cephalosporin, and against