The most important aspect of prevention is to minimize the duration and use of catheterization. Intermittent catheterization is preferred over indwelling catheter drainage whenever feasible. Insertion of catheters must be performed with aseptic technique, and the drainage system must remain closed at all times, with sterile technique used whenever the system is entered. Drainage bags always should be dependent to avoid backflow of urine into the bladder.
Indwelling catheters used for peritoneal dialysis may develop exit site infections, tunnel infections, or lead to peritonitis. The usual route of infection is from the skin surface along the tunnel and into the peritoneum. The most common pathogens are skin flora, including Staphylococcus; organisms that contaminate water, such as Pseudomonas and Acinetobacter; enteric flora, such as E. coli and Klebsiella; and fungi, such as
C. albicans. Peritonitis may present with fever, vague abdominal pain, and cloudy dialysate. The diagnosis is established on clinical manifestations and confirmed by culture of the dialysate. Prevention of infection requires careful planning of the location of the exit site to minimize contamination, aseptic insertion of the catheter, meticulous care of the catheter site, securing of the catheter to avoid tension and motion, and aseptic technique during dialysis.
Important risk factors of health care–associated central nervous system infections are surgery, ventriculoperitoneal shunts, and cerebrospinal fluid (CSF) leaks. Infection of ventriculoperitoneal shunts results from contamination of the system at the time of placement or from hematogenous seeding. Externalized ventricular drains and subdural bolts allow direct access of skin flora to the CSF. For these devices, the rates of infection increase with the duration of catheterization, especially beyond 5 days.
The most common pathogens causing shunt infections are coagulase-negative staphylococci and S. aureus. After skull fracture or cranial surgery, a CSF fistula leak may facilitate ascending infection from the nasopharynx, especially with Streptococcus pneumoniae, which frequently colonizes the nasopharynx. Patients with shunt infections may present with only fever and headache, or may present with typical signs and symptoms of meningitis (see Chapter 100). Infections caused by coagulase-negative staphylococci typically present with insidious onset of fever, malaise, headache, and vomiting. Empirical therapy is with vancomycin, with additional antibiotics if gram-negative bacteria are suspected.
Antibiotics frequently are used perioperatively during placement of shunts and other neurosurgical procedures. There is no proof that antibiotics decrease infection rates in these clean procedures. External ventricular drains should be maintained as closed systems with aseptic technique and removed as soon as possible. Drainage bags always should be dependent to avoid backflow.
Zoonoses are infections that are transmitted in nature between vertebrate animals and humans. Many zoonotic pathogens are maintained in nature by means of an enzootic cycle, in which mammalian hosts and arthropod vectors reinfect each other. Humans frequently are only incidentally infected. Of the more than 150 different human zoonotic diseases that have been described (Table 122-1), Lyme disease (Borrelia burgdorferi)accounts for 90% of reported vector-borne infections in the United States. Other common pathogens include Rickettsia rickettsii (Rocky Mountain spotted fever), ehrlichiosis (Ehrlichia chaffeensis), West Nile virus, and anaplasmosis (Anaplasma phagocytophilum). The epidemiology of zoonoses is related to the geographic distribution of the hosts and, if vector-borne, the distribution and seasonal life cycle of the vector.