Post splenectomy infection

Dr. M. Shahparianpour

Spleen

consists of the capsule and trabeculae which enclose the pulp.

3 zones of the pulp

a. White pulp – lymph node; contains lymphocytes, macrophages, and plasma cells in a reticular network

b. Red pulp – consists of the cord and sinuses; contains the cellular elements of the blood

c. Marginal zone – poorly defined vascular space between pulps; contains sequestered foreign material and plasma as well as abnormal cellular elements

histology

The role of the spleen in the prevention of

bacterial infections

It acts as an endothelial filtration organ for bacteria and other foreign material through:

phagocytosis and the production of opsonins including antigen-specific IgM, alternate complement components, properdin, and tuftsin

One of its most important immune functions is responding to blood-borne particulate antigens in the nonimmune host.

The spleen provides the most effective primary IgM response to encapsulated bacteria

There also seems to be a relationship between the quantity and quality of spleen and protection against sepsis:

splenic function after subtotal splenectomy for splenic injury is preserved and may be adequate to prevent severe postsplenectomy sepsis

The propensity for pneumococcal infections in patients with sickle cell disease underscores the importance of qualitative splenic function to protect against sepsis

Etiology of asplenia and hyposplenia

Asplenia refers to the absence of the spleen. The most common cause of asplenia is

surgical removal of the spleen:

Hypersplenism accounts for up to 50% of splenectomies, whereas trauma accounts for 10% to 30%

A rare cause of asplenia is congenital agenesis of the spleen.

This may occur as an isolated finding or as part of a syndrome often associated with cardiovascular abnormalities, such as Ivemark’s syndrome.

Hyposplenism refers to a poorly functioning, but intact spleen

Functional aspleniaAutoimmune DiseasePBCSLE Sjogrens

Intestinal DisorderCeliac diseaseCrohn’sUC

Haematological DiseaseSickle cellEssential thrombocytopenia

Infiltrative DiseaseAmyloidSarcoidosis

NeoplasiaBreast CancerHaematological malignancy

MiscellaneousAlcoholismBMTTPNSplenic Thrombosis

The risk of developing severe infection remains a significant complication of asplenia (surgical splenectomy or congenital asplenia) and hyposplenia,

especially in children under the age of 5 years

Splenic salvage methods (eg, partial splenectomy) are practiced with specific indications, the goal being to preserve some of the splenic immune function.

Whether partial splenectomy renders the same risk of developing overwhelming postsplenectomy sepsis (OPSS) as total splenectomy and whether the same preventative measures should be taken, remain unclear.

Definition of OPSI

OPSI may have a short prodrome with non-specific symptoms

Evolve into septic shock and DICClinical course measured in hours rather

than daysFever most common – most report rigors

1 - 2 days prior to presentation In adults OPSI usually cryptic infection

without primary source

It is well known that asplenia or hyposplenia convey an increased lifetime risk of developing severe infections to an affected individual, regardless of:

age, the cause of asplenia or hyposplenia, in the case of splenectomy, the duration

of time from removal of the spleen

the incidence seems to be related to age and underlying disease :

Splenectomized children under the age of 15 years are at greater risk of developing OPSS than adults

The incidence of OPSS is higher in children with

underlying hemoglobinopathies (thalassemia major and sickle cell disease) and hereditary spherocytosis than in those who undergo splenectomy because of trauma

Risk of OPSI can be stratified according to underlying disease

Low risk Trauma

Intermediate risk

SpherocytosisITPPortal Hypertension

High risk

Thalassaemiasickle cell diseaseHodgkin's DiseaseMalignancy

Risk of post splenectomy sepsis low but carries high risk of death (50-80%)

If patients are educated to seek attention immediately may be reduced to about 10%

More than 50% who die do so within 48 hours of admission

Children: 1/175 patient yearsAdults: 1/400~500 patient yearsHighest risk at first few years

1/3 at first year1/2 at first 2 yearsHowever, 1/3 after first 5 years

Can happen even 20 years after splenectomy

Clinical manifestations Fever

Any fever must be viewed as possible PSS

BacteremiaCoagulopathy

Purpura, petechiaeMeningitis

Headache, neck stiffness, seizureRespiratory symptoms

Cough, dyspnea, respiratory failureGI symptoms

Nausea, vomiting, diarrhea, GI bleedingShock

The mortality rate of sepsis associated with asplenia or hyposplenia remains high; death occurs in 50% to 70% of those afflicted

Mortality rates are also age related, with the highest rates reported in those children less than 2 years of age

Common pathogens

Encapsulated pathogenStreptococcus pneumoniae(50~60 %)

No particular serotype is more commonHaemophilus influezae(20~30 %)Neisseria spp.(10~20 %)Other uncommon pathogens:

Capnocytophaga canimorsus Common flora in oral cavity of dogs and cats

Bordetella holmesii

Capnocytophaga canimorsus

LABCBCBlood smearDIC profileLumbar punctureCXRBlood culture

ManagementBraod-spectrum antibiotics

Based on expert opinionMust cover:

penicillin-resistant pneucoccus beta-lactamase producing H.influenzae

General suggestionCeftriaxone + VancomycinLevofloxacin + Vancomycin

Life-support measuresH/D or CVVH for ARFVentilatorInotropic agentsFluid

Prevention Avoid unnecessary splenectomy

ImmunizationTiming

14 days before splenectomy 14 days after splenectomy (not immediately)

Pneumococcal vaccine PPV-23 for adults PCPV-7 for children and some adults

Haemophilus B vaccineMeningococcal vaccineRe-immunizationOther vaccines: influenza vaccine

Antibiotic prophylaxisDaily penicillin

Reduce incidence by halfReduce mortality by 80 percentsLife-long or 3~5years?Post PSS patients

Abx for feverOn handEmpirical: Augmentin, Cefuroxine,

fluoroquinolones

When fever, Take the drug and go to doctor without delay

Abx for dental procedures

Not recommended for no obvious advantage

Influenza

Annual Influenza vaccine

HiB Vaccine

Previously non immunised adults should receive a single dose of vaccine.

Meningitis C vaccine

Previously non immunised adults should receive a single dose of vaccine

If poor response give conjugate (Prevenar) if not already given.

Anti-malarialsif travelling to endemic areasMeningitis A+C,W135,Y if appropriateAntibiotics‡

Good response recheck antibody titre in 1 year

Antibiotic cover

3 day supply of Amoxycillin should be kept by the patient with instructions to take 1gm at first sign of infection and 500mg tds thereafter and to seek immediate medical attention.

Check antibodies 4/52 post vaccination

ImmunisationAntibiotics

Travel †

Pneumococcal vaccine

Polysaccharide vaccine (Pneumovax). Avoid in pregnancy.

Poor response revaccinate and re-test at 4/52

Antibiotic prophylaxis (adult dose)

Penicillin V 500mg b.d.Amoxycillin 500mg bd(Erythromycin 250mg od if penicillin allergy)

Absent or dysfunctional spleen in adults

†Discuss with Adult Infectious Disease team

‡Antibiotic prophylaxis may need altering depending upon local resistance.

Malaria

Lack of splenic clearance of leads to high parasitaemia

Increased risk of fulminant malaria

Antibiotic Prophylaxis 1. All patients, regardless of underlying condition, should be on lifelong antibiotic prophylaxis. This should be either Penicillin V or Amoxycillin,

with a preference for Penicillin V. Adult doses:

Penicillin V 500 mg b.d. Amoxycillin 500 mg o.d.

 2. For penicillin allergic patients, Erythromycin 250

mg b.d. should be used.

3. Patients travelling to areas where penicillin-resistant pneumococci have been identified should be

switched from Penicillin V to Amoxycillin before travelling and for one week after return.

Immunization4. Asplenia in itself is not a contraindication to routine immunization.

Normal inoculations, including live vaccines, can be given safely to adults with absent or dysfunctional spleens. 5. All splenectomised patients and those with functional hyposplenism should receive pneumococcal immunisation; Haemophilus influenzae type B [Hib] conjugate vaccine and conjugated meningococcal C vaccine [MenC] as soon as possible.

For pneumococcal vaccination the 23-polyvalent pneumococcal vaccine [Pneumovax] should be used. 

THANKS FOR YOUR ATTENTIONS