Editing Overwhelming post-splenectomy infection

{{Infobox medical condition
| name          = Overwhelming post-splenectomy infection
| synonym       = '''Overwhelming post-splenectomy sepsis''' ('''OPSS''')<ref>surgical recall, seventh edition, Lorne H. Blackbourne, page 469.</ref>
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| specialty     = [[Infectious disease]]
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| onset         = 24–48 hours following presentation with mild viral symptoms<ref name="Luu2019" />
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| causes        = Exposure to pathogens following [[splenectomy]] or [[asplenia]]
| risks         = [[Splenectomy]] in the past 2–3 years, removal of spleen for [[hematological]] reasons, being under the age of 2<ref name="Luu2019" />
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| prognosis     = Almost invariably fatal without treatment<ref name="Luu2019">{{Cite journal|last1=Luu|first1=Sarah|last2=Spelman|first2=Denis|last3=Woolley|first3=Ian J.|date=2019|title=Post-splenectomy sepsis: preventative strategies, challenges, and solutions|journal=Infection and Drug Resistance|volume=12|pages=2839–2851|doi=10.2147/IDR.S179902|issn=1178-6973|pmc=6748314|pmid=31571940 |doi-access=free }}</ref>
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An '''overwhelming post-splenectomy infection''' ('''OPSI''') is a rare but rapidly fatal [[infection]] occurring in individuals following [[Splenectomy|removal]] (or [[Asplenia|permanent dysfunction]]) of the [[spleen]]. The infections are typically characterized by either [[meningitis]] or [[sepsis]], and are caused by [[bacterial capsule|encapsulated organisms]] including ''[[Streptococcus pneumoniae]]''.<ref name="pmid11253134">{{cite journal |author=Waghorn DJ |title=Overwhelming infection in asplenic patients: current best practice preventive measures are not being followed |journal=Journal of Clinical Pathology |volume=54 |issue=3 |pages=214–8 |date=March 2001 |pmid=11253134 |pmc=1731383 |doi= 10.1136/jcp.54.3.214}}</ref> It is a [[medical emergency]] and requires immediate treatment. Death has been reported to occur within 12 hours.<ref name=":0" />

The spleen is necessary for protection against [[Bacterial capsule|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 [[Influenza-like illness|mild viral symptoms]] to [[sepsis]] is one of the things that makes OPSI particularly dangerous.

Another source of infection<ref>{{cite journal |last1=Rosner |first1=F. |title=Babesiosis in splenectomized adults. Review of 22 reported cases. |journal=American Journal of Medicine |date=April 1984 |volume=76 |issue=4 |pages=696–701 |pmid=6424470|doi=10.1016/0002-9343(84)90298-5 }}</ref> are species of ''[[Babesia]]'', which are tick-borne parasites that cause [[babesiosis]].<ref>{{cite web |last1=Centers for Disease Control and Prevention |title=About Babesiosis |url=https://www.cdc.gov/parasites/babesiosis/gen_info/index.html |website=CDC Parasites |access-date=19 June 2018}}</ref>

== Signs and symptoms ==
OPSI may initially present with [[Influenza-like illness|mild viral symptoms]] such as fever or coughing, however later in infection symptoms may include shakes, [[Shivering|shivers]], [[chills]], [[diarrhea]], [[vomiting]], [[malaise]], [[myalgia]], [[headache]] and [[abdominal pain]].<ref name="Luu2019" /><ref name=":0">{{Cite journal|last1=Taniguchi|first1=Leandro Utino|last2=Correia|first2=Mário Diego Teles|last3=Zampieri|first3=Fernando Godinho|date=December 2014|title=Overwhelming post-splenectomy infection: narrative review of the literature|url=https://pubmed.ncbi.nlm.nih.gov/25318011/|journal=Surgical Infections|volume=15|issue=6|pages=686–693|doi=10.1089/sur.2013.051|issn=1557-8674|pmid=25318011}}</ref>

The disease progresses rapidly from the above mentioned symptoms to [[coma]] to refractory [[septic shock]] and finally death in as little as 24 hours.<ref name=":0" />

==Mechanism==
The [[spleen]] contains many [[macrophage]]s (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 [[Immunoglobulin G|IgG]] [[antibodies]] (IgG1 or IgG3) or the [[Complement system|complement]] component C3b.  These types of antibodies and complement are immune substances called [[opsonizer]]s, 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 [[immunization]]s against [[pathogen]]s 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 [[polysaccharide]]s (sugars) permit bacteria to evade phagocytosis by macrophages alone, since only [[protein]]s 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]].<ref name="pmid11843905">{{cite journal|vauthors=Davidson RN, Wall RA|date=December 2001|title=Prevention and management of infections in patients without a spleen|journal=Clinical Microbiology and Infection|volume=7|issue=12|pages=657–60|doi=10.1046/j.1198-743x.2001.00355.x|pmid=11843905|doi-access=free}}</ref><ref name="BMJ1996">{{cite journal | title=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 | journal=BMJ | year=1996 | pages=430–4 | volume=312 | issue=7028 | pmid=8601117 | url=http://bmj.bmjjournals.com/cgi/content/full/312/7028/430 | pmc= 2350106 | doi=10.1136/bmj.312.7028.430| author1=Working Party of the British Committee for Standards in Haematology Clinical Haematology Task Force }}</ref><ref name="BMJ2001">{{cite journal  |vauthors=Davies JM, etal | title=The prevention and treatment of infection in patients with an absent or dysfunctional spleen - British Committee for Standards in Haematology Guideline up-date | journal=BMJ | date=2001-06-02 |  url= |volume=312|issue=7028|pages=430–4|doi=10.1136/bmj.312.7028.430 | pmid=8601117 | pmc=2350106}}</ref>

=== 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.<ref name=":1">{{Cite journal|last1=Downing|first1=Mark A.|last2=Omar|first2=Ahmed H.|last3=Sabri|first3=Elham|last4=McCarthy|first4=Anne E.|date=August 2011|title=Information on the Internet for asplenic patients: a systematic review|journal=Canadian Journal of Surgery|language=en|volume=54|issue=4|pages=232–236|doi=10.1503/cjs.005510|pmid=21651833|pmc=3191896}}</ref> 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.<ref name=":1" /> The majority (as many as 84%) of asplenic individuals are unaware of the risks of asplenia.<ref name=":0" /> Encouraging the wearing of [[Medical identification tag|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 [[Animal bite|bite from an animal]] has been shown to reduce OPSI risk.<ref name=":0" /><ref name="Luu2019" />

===Vaccination===
The [[Centers for Disease Control and Prevention]]'s annual vaccine recommendations includes specifics for individuals without a functioning spleen.<ref>{{cite web |title=2018 Adult Schedule by Health Conditions in Easy-to-read Format for Patients |url=https://www.cdc.gov/vaccines/schedules/easy-to-read/adult-conditions-easyread.html |website=Centers for Disease Control and Prevention |access-date=19 June 2018}}</ref>

[[The Green Book (immunisation guidance, UK)]] in chapter 7<ref>{{cite web |title=Immunisation of individuals with underlying medical conditions: the green book, chapter 7 |date=10 January 2020 |url=https://www.gov.uk/government/publications/immunisation-of-individuals-with-underlying-medical-conditions-the-green-book-chapter-7 |access-date=2023-08-24}}</ref> 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.<ref>{{cite web |author1=Camille Nelson Kotton |author2=Andrew T. Kroger |author3=David O. Freedman |author-link1=Immunocompromised Travelers |title=Advising Travelers with Specific Needs |url=https://wwwnc.cdc.gov/travel/yellowbook/2018/advising-travelers-with-specific-needs/immunocompromised-travelers |website=Travelers' Health |access-date=25 October 2018}}</ref>

==Prognosis==
OPSI is almost always fatal without treatment, but modern treatment has decreased the mortality to approximately 40–70 percent.<ref name="Luu2019" /><ref name="pmid11253134"/><ref name="pmid7131680">{{cite journal |vauthors=Schwartz PE, Sterioff S, Mucha P, Melton LJ, Offord KP |title=Postsplenectomy sepsis and mortality in adults |journal=Journal of the American Medical Association |volume=248 |issue=18 |pages=2279–83 |date=November 1982 |pmid=7131680 |doi= 10.1001/jama.248.18.2279}}</ref> Individuals with OPSI are most commonly treated with [[antibiotic]]s and supportive care.<ref name="pmid11843905"/>

== Epidemiology ==
The risk of OPSI is 0.23–0.42 percent per year, with a lifetime risk of 5 percent.<ref name="pmid11843905" /> Most infections occur in the first few years following [[splenectomy]], but the risk of OPSI is lifelong.<ref name="pmid11253134"/><ref name="pmid2070242">{{cite journal |vauthors=Cullingford GL, Watkins DN, Watts AD, Mallon DF |title=Severe late postsplenectomy infection |journal=The British Journal of Surgery |volume=78 |issue=6 |pages=716–21 |date=June 1991 |pmid=2070242 |doi= 10.1002/bjs.1800780626|s2cid=23790214 }}</ref>

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 [[Hematologic disease|hematological conditions]] such as [[Sickle-Cell Anemia|sickle cell anemia]], [[thalassemia]] and [[Splenic tumor|tumours]] when compared to splenectomy due to [[Splenic injury|trauma]].<ref name="Luu2019" /><ref name=":0" />
==References==
{{reflist|2}}

[[Category:Bacterial diseases]]
[[Category:Medical emergencies]]
[[Category:Spleen (anatomy)]]