Overwhelming post-splenectomy infection
Other namesOverwhelming post-splenectomy sepsis (OPSS)[1]
SpecialtyInfectious disease
Usual onset24–48 hours following presentation with mild viral symptoms[2]
CausesExposure to pathogens following splenectomy or asplenia
Risk factorsSplenectomy in the past 2–3 years, removal of spleen for hematological reasons, being under the age of 2[2]
PrognosisAlmost invariably fatal without treatment[2]

An overwhelming post-splenectomy infection (OPSI) is a rare but rapidly fatal infection occurring in individuals following removal (or permanent dysfunction) of the spleen. The infections are typically characterized by either meningitis or sepsis, and are caused by encapsulated organisms including Streptococcus pneumoniae.[3] It is a medical emergency and requires immediate treatment. Death has been reported to occur within 12 hours.[4]

The spleen is necessary for protection against encapsulated bacteria (see Mechanism) and as such when removed by splenectomy it can lead to rapid unchallenged infection by encapsulated bacteria. The rapid progression from mild viral symptoms to sepsis is one of the things that makes OPSI particularly dangerous.

Another source of infection[5] are species of Babesia, which are tick-borne parasites that cause babesiosis.[6]

Signs and symptoms

OPSI may initially present with mild viral symptoms such as fever or coughing, however later in infection symptoms may include shakes, shivers, chills, diarrhea, vomiting, malaise, myalgia, headache and abdominal pain.[2][4]

The disease progresses rapidly from the above mentioned symptoms to coma to refractory septic shock and finally death in as little as 24 hours.[4]

Mechanism

The spleen contains many macrophages (part of the reticuloendothelial system), which are immune cells that phagocytose (eat) and destroy bacteria. In particular, these macrophages are activated when bacteria are bound by IgG antibodies (IgG1 or IgG3) or the complement component C3b. These types of antibodies and complement are immune substances called opsonizers, molecules that bind to the surface of bacteria to facilitate phagocytosis.

When the spleen is no longer present (asplenia), IgG and C3b are still bound to bacteria, but they cannot be removed from the blood circulation due to the loss of the splenic macrophages. Hence the bacteria are free to cause infection.

Patients without a spleen often need immunizations against pathogens that normally require opsonization and phagocytosis by macrophages in the spleen. These include common human pathogens with bacterial capsules (Streptococcus pneumoniae, Salmonella typhi, Neisseria meningitidis, E. coli, Hemophilus influenzae, Streptococcus agalactiae, Klebsiella pneumoniae, Pseudomonas aeruginosa). Capsules made of polysaccharides (sugars) permit bacteria to evade phagocytosis by macrophages alone, since only proteins are directly recognized by macrophages in phagocytosis. So humoral immunity in forms of IgG and complement proteins is the human immune system's response against bacterial capsules.

Prevention

Measures to prevent OPSI include vaccination, prophylactic antibiotics and patient education.[7][8][9]

Patient education

Knowledge of the risks of asplenia correlates with a greatly reduced risk of OPSI, thus patient education is vital to preventing OPSI and may be the most important factor for preventing OPSI.[10] More and more people are increasingly getting their healthcare information from the internet and the lack of reliable, readable and comprehensive information on the risks of asplenia and splenectomy poses a preventable risk factor for asplenic individuals.[10] The majority (as many as 84%) of asplenic individuals are unaware of the risks of asplenia.[4] Encouraging the wearing of bracelets with information about the condition, the carrying of antibiotics, seeking medical advice before travel, especially to places where malaria and babesia is endemic and seeking immediate medical attention following a bite from an animal has been shown to reduce OPSI risk.[4][2]

Vaccination

The Centers for Disease Control and Prevention's annual vaccine recommendations includes specifics for individuals without a functioning spleen.[11]

The The Green Book (immunisation guidance, UK) in chapter 7[12] covers immunisation of people with underlying medical conditions that affect immunity which includes asplenic patients.

As there are a range of different pneumococcal vaccines, the patient should be offered the most up to date ones (typically 23 valent polysaccharide vaccine and 13 valent conjugate vaccine), if they have not had them already as part of standard schedule. Repeat doses are recommended in patients without a spleen.

The CDC recommends against live vaccines and has specific advice for travellers, which includes malaria avoidance for asplenic individuals.[13]

Prognosis

OPSI is almost always fatal without treatment, but modern treatment has decreased the mortality to approximately 40–70 percent.[2][3][14] Individuals with OPSI are most commonly treated with antibiotics and supportive care.[7]

Epidemiology

The risk of OPSI is 0.23–0.42 percent per year, with a lifetime risk of 5 percent.[7] Most infections occur in the first few years following splenectomy, but the risk of OPSI is lifelong.[3][15]

The risk is greatest for children and elderly (70+ years old), but it can happen at any age. Greater risk is associated with splenectomy for hematological conditions such as sickle cell anemia, thalassemia and tumours when compared to splenectomy due to trauma.[2][4]

References

  1. ↑ surgical recall, seventh edition, Lorne H. Blackbourne, page 469.
  2. 1 2 3 4 5 6 7 Luu, Sarah; Spelman, Denis; Woolley, Ian J. (2019). "Post-splenectomy sepsis: preventative strategies, challenges, and solutions". Infection and Drug Resistance. 12: 2839–2851. doi:10.2147/IDR.S179902. ISSN 1178-6973. PMC 6748314. PMID 31571940.
  3. 1 2 3 Waghorn DJ (March 2001). "Overwhelming infection in asplenic patients: current best practice preventive measures are not being followed". Journal of Clinical Pathology. 54 (3): 214–8. doi:10.1136/jcp.54.3.214. PMC 1731383. PMID 11253134.
  4. 1 2 3 4 5 6 Taniguchi, Leandro Utino; Correia, Mário Diego Teles; Zampieri, Fernando Godinho (December 2014). "Overwhelming post-splenectomy infection: narrative review of the literature". Surgical Infections. 15 (6): 686–693. doi:10.1089/sur.2013.051. ISSN 1557-8674. PMID 25318011.
  5. ↑ Rosner, F. (April 1984). "Babesiosis in splenectomized adults. Review of 22 reported cases". American Journal of Medicine. 76 (4): 696–701. doi:10.1016/0002-9343(84)90298-5. PMID 6424470.
  6. ↑ Centers for Disease Control and Prevention. "About Babesiosis". CDC Parasites. Retrieved 19 June 2018.
  7. 1 2 3 Davidson RN, Wall RA (December 2001). "Prevention and management of infections in patients without a spleen". Clinical Microbiology and Infection. 7 (12): 657–60. doi:10.1046/j.1198-743x.2001.00355.x. PMID 11843905.
  8. ↑ Working Party of the British Committee for Standards in Haematology Clinical Haematology Task Force (1996). "Guidelines for the prevention and treatment of infection in patients with an absent or dysfunctional spleen. Working Party of the British Committee for Standards in Haematology Clinical Haematology Task Force". BMJ. 312 (7028): 430–4. doi:10.1136/bmj.312.7028.430. PMC 2350106. PMID 8601117.
  9. ↑ Davies JM, et al. (2001-06-02). "The prevention and treatment of infection in patients with an absent or dysfunctional spleen - British Committee for Standards in Haematology Guideline up-date". BMJ. 312 (7028): 430–4. doi:10.1136/bmj.312.7028.430. PMC 2350106. PMID 8601117.
  10. 1 2 Downing, Mark A.; Omar, Ahmed H.; Sabri, Elham; McCarthy, Anne E. (August 2011). "Information on the Internet for asplenic patients: a systematic review". Canadian Journal of Surgery. 54 (4): 232–236. doi:10.1503/cjs.005510. PMC 3191896. PMID 21651833.
  11. ↑ "2018 Adult Schedule by Health Conditions in Easy-to-read Format for Patients". Centers for Disease Control and Prevention. Retrieved 19 June 2018.
  12. ↑ "Immunisation of individuals with underlying medical conditions: the green book, chapter 7". Retrieved 2023-08-24.
  13. ↑ Camille Nelson Kotton; Andrew T. Kroger; David O. Freedman. "Advising Travelers with Specific Needs". Travelers' Health. Retrieved 25 October 2018.
  14. ↑ Schwartz PE, Sterioff S, Mucha P, Melton LJ, Offord KP (November 1982). "Postsplenectomy sepsis and mortality in adults". Journal of the American Medical Association. 248 (18): 2279–83. doi:10.1001/jama.248.18.2279. PMID 7131680.
  15. ↑ Cullingford GL, Watkins DN, Watts AD, Mallon DF (June 1991). "Severe late postsplenectomy infection". The British Journal of Surgery. 78 (6): 716–21. doi:10.1002/bjs.1800780626. PMID 2070242. S2CID 23790214.
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