Prevention of central nervous system infections in patients at risk

Infections of the central nervous system in patients at risk are relatively uncommon when compared with pneumonia, bacteremia, and soft tissue infection. However, they carry serious morbidity and are frequently fatal. Each of the diverse conditions that can place a patient at risk for central nervous system infection is associated with a fairly predictable spectrum of etiologic organisms. Various forms of trauma (including blunt and penetrating injuries and neurosurgery, especially when a cerebrospinal fluid shunt is implanted) predispose to infection with common pathogenic bacteria. Defects of cellular immunity including congenital immune deficiencies, immunosuppressive drug therapy, leukemia, lymphoma, and the acquired immune deficiency syndrome are more likely to give rise to infection with a distinctive spectrum of opportunistic viruses, fungi, and protozoa. Other underlying conditions include sinus, ear, and mastoid infections, congenital heart disease, intrathoracic suppuration, endocarditis, and bacteremia, hypogammaglobulinemia, and complement deficiencies. Some preventive measures including vaccines, antibiotics, and surgical procedures are available. However, for many of these central nervous system infections, preventive measures are lacking or less effective than those for infections in other organs. In the future, opportunistic central nervous system infections will increase in frequency as the number of patients at risk continues to grow.