considered in asplenic individuals two years or older. Pneumococcal conjugate vaccine is used
for routine vaccination of children younger than 24 months and children 24 to 59 months with
high-risk medical conditions including asplenia (61). In order to expand the spectrum of
protection against pneumococcal disease, consideration should be given to use of both
vaccines in all age groups.
Haemophilus Influenzae type B Vaccine
TheHaemophilusvaccine has been shown to be immunogenic in patients with impaired splenic
function associated with sickle cell anemia (62). The specific concentration of antibody
required in patients lacking a spleen is not known. In general,H. influenzae type B(HiB)
vaccination of persons older than 59 months of age is not recommended. Previously non-
vaccinated persons older than 59 months having high-risk condition like functional or
anatomic asplenia should be given at least one pediatric dose of a HiB conjugate vaccine (63).
The requirement for reimmunization is not defined.
Meningococcal Vaccine
The quadrivalent, unconjugated capsular meningococcal vaccine (type A, C, Y, and W135) is
immunogenic in the asplenic patient but less so in those patients who are also treated with
chemotherapy and radiotherapy (64). Vaccine is recommended for persons with increased risk
of meningococcal disease, including persons with functional or anatomical asplenia. The
efficacy and importance of meningococcal vaccination in splenectomized individuals is
unknown. The antibody levels rapidly decline in two to three years and postsplenectomy
patients will always be at risk, revaccination may be considered five years after receipt of the
first dose. The quadrivalent conjugated meningococcal vaccine is used for routine immuni-
zation of adolescents and persons 2 to 55 years of age who are at increased risk of
meningococcal disease, which includes asplenia (65). The exact duration of protection is
unknown but is longer than polysaccharide vaccine.
Influenza Vaccine
Annual administration of influenza virus vaccine is recommended in asplenic or hyposplenic
individuals to prevent the primary disease as well as complications of secondary bacterial
infections (33).
Chemoprophylaxis
The first one to three years after splenectomy is the most important time for the risk of
infection and mortality. Therefore, the institution of antibiotic prophylaxis in this period is
likely to reduce morbidity and mortality. The risk of infection declines significantly beyond
that time, and continuing antibiotic prophylaxis would provide lesser benefits. Since most
patients are unwilling to take antibiotics lifelong, they should be persuaded to take antibiotics
for at least three years, in addition to vaccines as described above. The likelihood of a second or
third infection is high in the first six months after a first infection and antibiotic prophylaxis
could offer the most benefit in this period for patients who have had a first severe infection
(66). Some guidelines advocate continuing the antibiotic prophylaxis in children for five years
or until the age of 21. Such approach in adults has never been evaluated. Compliance is a
problem in long-term prophylaxis in adults as is the inevitable selection for colonization with
nonsusceptible pathogens. A single daily dose of penicillin or amoxicillin is the regimen of
choice, but these antibiotics will not protect against organisms resistant to penicillin.
Cefotaxime or ceftriaxone have been recommended as presumptive treatment for symptomatic
patients who have been taking antibiotic prophylaxis or those with strains known to show
intermediate resistance to penicillin (33,67).
Self-treatment
The other strategy is the provision of standby antipneumococcal antibiotics, i.e., the patient
retains a personal supply of antibiotics to be taken at first sign of respiratory illness, fever, or
Severe Infections in Asplenic Patients in Critical Care 355