Techniques to Detect IV Catheter Associated Infections

The insertion of an IV catheter during hospitalization is common practice. Infection, either locally at the catheter insertion site or bacteremia, is one of the most common complications of catheter placement. Because the skin of all patients is colonized with microorganisms that are also common pathogens in catheters, techniques used to diagnose catheter-related infections attempt to quan-titate bacterial growth. Diagnosis of an IV catheter-related bacteremia (or fungemia) is difficult, because there are often no signs of infection at the catheter insertion site and the typical signs and symptoms of sepsis can overlap with other clinical manifestations; even the finding of a positive blood culture does not identify the catheter as die source. To date, various methods, such as semiquantitative cultures, Gram stains of the skin entry site, and culture of IV catheter tips following catheter removal, have been described to identify these infections. Many of these methods involve some type of quantitation in an attempt to differentiate colonization of the catheter from probable infection. IWo major approaches to the diagnosis of catheter-related infection (CRI) in which the catheter remains in place are based on the premise that a greater number of organisms will be present in the intravascular catheter compared to the number found in blood specimens obtained from distant peripheral veins. The first approach, differential quantitative cultures, involves drawing two blood cultures—one from a peripheral site and the other from the suspected infected line. Quantitative cultures are processed for each specimen in which the same volume of blood is inoculated to standard microbiology media and colonies counted the following day. A colony count ratio greater than 4 to 10:1 between the central venous blood and a peripheral vein blood specimens indicates a probable CRI with a sensitivity of 78% to 94% and a specificity of 99% to 100%. The second approach involves the comparison of the differential time to positivity of blood specimens obtained from a peripheral and intravascular site; a differential time to positivity greater than 2 hours between bottles inoculated with blood from the catheter and those from a peripheral vein indicates a probable CRI.3 Unfortunately, no single method has demonstrated a dear clinical benefit in diagnosing CRI and remains unsettled.

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Figure 52-7 A, Blood culture bottles for the BACTEC 9240, 9120, and 9050 continuous monitoring instruments. B, The BACTEC 9240 continuous monitoring blood culture system. C; Blood culture bottles for the BaCT/ALERT continuous monitoring blood culture instruments.

Figure 52-7—cont'd D, The BacT/ALERT continuously monitoring blood culture system. E, Blood culture bottles for Trek Diagnostic Systems, Inc., ESP Culture System II continuous monitoring instrument.

Figure 52-7—cont'd F, ESP continuous monitoring blood culture system. (A and B courtesy Becton Dickinson Microbiology Systems, Sparks, Md; BACTEC is a trademark of Becton Dickinson Microbiology Systems. C and D courtesy bioMerleux, Durham, NC. E and F courtesy Trek Diagnostic Systems, Inc., Cleveland, Ohio.)

Figure 52-7—cont'd F, ESP continuous monitoring blood culture system. (A and B courtesy Becton Dickinson Microbiology Systems, Sparks, Md; BACTEC is a trademark of Becton Dickinson Microbiology Systems. C and D courtesy bioMerleux, Durham, NC. E and F courtesy Trek Diagnostic Systems, Inc., Cleveland, Ohio.)

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Bacterial Vaginosis Facts

Bacterial Vaginosis Facts

This fact sheet is designed to provide you with information on Bacterial Vaginosis. Bacterial vaginosis is an abnormal vaginal condition that is characterized by vaginal discharge and results from an overgrowth of atypical bacteria in the vagina.

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