S. aureus and coagulase-negative staphylococci such as oxacillin, nafcillin, or vancomycin. Antibiotic regimens should be tailored to the specific organism identified. Eradication of infection can be accomplished without removal of the central line in 89% of uncomplicated bacteremic infections, 94% of exit site infections, and 25% of tunnel infections. If the patient is not critically ill and the pathogen is likely to be susceptible to antibiotic therapy, a trial of antibiotics is given through the infected catheter. The total duration of therapy depends on the pathogen and the duration of positive cultures and is usually 10 to 14 days after sterilization of the bloodstream. Catheter removal is indicated with sepsis, septic thrombophlebitis, clinical deterioration (despite appropriate therapy), persistently positive blood culture results after 48 to 72 hours of appropriate antimicrobial therapy, embolic lesions, or fungal infection because of poor response to antifungal therapy alone (see Fig. 121-1). Infection of the pocket around an implanted port is unlikely to respond to antibiotics, and removal of the foreign body is usually necessary.
Antibiotic-lock is a method of sterilizing intravascular catheters by using high concentrations of antibiotics infused into the portion of the catheter between the hub and the vessel entry. The solution is allowed to dwell within the catheter segment for several hours. It also may be useful for treatment of catheter-associated infections and for prevention of infection.
Aseptic technique is essential during catheter insertion. Catheters that are placed during emergency situations should be replaced as soon as medically feasible. Care of indwelling catheters involves meticulous attention to sterile technique whenever the system is entered. Care of the catheter entry site commonly involves a topical antibiotic or disinfectant. Catheters that are no longer necessary should be removed.
Intubation of the airway provides direct access to the lungs and bypasses normal host defenses. Organisms enter the lungs directly through the lumen of the tube or by descending around the tube, which may result in ventilator-associated pneumonia. Contaminated respiratory equipment, humidification systems, or condensate introduces bacteria directly into lower airways. The continuously open upper airway increases the risk of aspiration of oropharyngeal flora and reflux of gastric contents and interferes with clearance of the airway by coughing because an effective cough requires a closed glottis. Suctioning of the upper respiratory tract or mouth requires clean technique but does not require aseptic technique. Suction catheters that reach the lower airways must be sterile and usually are designed for single use.
The most important risk factors for urinary tract infections (UTIs) are the presence of catheters, instrumentation, and anatomic abnormalities (see Chapter 114). Organisms enter the bladder through the catheter by instillation of contaminated irrigation fluids, backflow of contaminated urine from the drainage bag, or ascent of bacteria around the meatus along the outside of the catheter. Indwelling catheters facilitate direct access to the bladder and should have a closed drainage system. After simple, straight catheterization, the incidence of UTI is 1% to 2%. Organisms that cause catheter-associated UTIs include fecal flora, such as gram-negative enteric bacilli, most commonly Escherichia coli, and Enterococcus. With concomitant antibiotic treatment, resistant organisms predominate, and fungi emerge as pathogens.