Current laboratory techniques in the diagnosis of catheter-related infections.
The unspecificity of the clinical manifestations of catheter-related infections (CRIs) makes laboratory confirmation necessary, and many diagnostic techniques have been developed. Semiquantitative culture of catheter tips has been accepted by most laboratories for its simplicity and is currently the reference technique. It discriminates between catheters producing infection (when > or = 15 colony forming units grow on the culture) and insignificant colonization. Nonquantitative methods improve the sensitivity of diagnosis of CRI but are less specific. Quantitative methods improve the specificity and can identify and quantify colonization of both the internal and external surfaces of the catheter; however, these are time-consuming techniques. The high rate of unnecessary catheter removal has promoted interest in in situ staining methods such as gram staining of the skin entry site and hub. These methods are simple to perform and have shown a high negative predictive value. Quantitative blood culture methods allow the diagnosis of CRI, but their sensitivity decreases in the absence of associated bacteremia. Finally, the introduction of molecular techniques has helped to explain the pathogenesis of CRI and could help to improve the management of nosocomial CRI.
Liñares
J
J
Servicio de Microbiologia, Hospital de Bellvitge, Barcelona, Spain.
Domínguez
M A
MA
Martín
R
R
D016470:Bacteremia / Q000175:diagnosis* / Q000209:etiology*; D015373:Bacterial Typing Techniques; D002405:Catheterization, Central Venous / Q000009:adverse effects*; D002406:Catheterization, Peripheral / Q000009:adverse effects*; D018929:Cell Culture Techniques / Q000379:methods; D006801:Humans; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods