Infections in Patients with Aplastic Anemia

Infection is a major cause of death in patients with aplastic anemia (AA). There are differences between the immunocompromised state of a patient with AA and the patient who is neutropenic due to chemotherapy and this leads to a difference in the infections that they incur. Prolonged neutropenia is one of the largest risk factors for the development of infections with the invasive mycoses and bacteria. Recovery from neutropenia is directly related to survival, and supportive care plays a large role in protection while the patient is in a neutropenic state. The most common invasive mycoses include the Aspergillus species, Zygomycetes, Candida spp., and Fusarium spp. Bacterial infections that are seen in patients with AA include gram-positive coagulase-negative Staphylococcus species, Enterococcus, Staphylococus aureus, Clostridium spp., Micrococcus, alpha-hemolytic streptococci, Listeria monocytogenes, and Bacillus cereus. Gram-negative infections including gram-negative bacilli, Escherichia coli, Salmonella, Bacteroides fragilis, Klebsiella oxytoca, Klebsiella pneumonia, Aeromonas hydrophilia, Pseudomonas aeruginosa, and Vibrio vulnificus. Viral infections are much less common but include those that belong to the Herpesviridae family, community-acquired respiratory viral infection, and the viral hepatitides A, B, and C. Evidence of the parasite Strongyloides stercoralis has also been documented. This review discusses the major invasive fungal infections, bacterial pathogens, parasites, and viral infections that are found in patients with AA who are treated with immunosuppressive therapy. The specific immune impairment and current treatment parameters for each of these classes of infection will also be discussed.