The Asplenic Patient: Post-Insult Immunocompetence, Infection, and Vaccination

Ten golden rules for optimal antibiotic use in hospital settings: the WARNING call to action

Antibiotics are recognized widely for their benefits when used appropriately. However, they are often used inappropriately despite the importance of responsible use within good clinical practice. Effective antibiotic treatment is an essential component of universal healthcare, and it is a global responsibility to ensure appropriate use. Currently, pharmaceutical companies have little incentive to develop new antibiotics due to scientific, regulatory, and financial barriers, further emphasizing the importance of appropriate antibiotic use. To address this issue, the Global Alliance for Infections in Surgery established an international multidisciplinary task force of 295 experts from 115 countries with different backgrounds. The task force developed a position statement called WARNING (Worldwide Antimicrobial Resistance National/International Network Group) aimed at raising awareness of antimicrobial resistance and improving antibiotic prescribing practices worldwide. The statement outlined is 10 axioms, or "golden rules," for the appropriate use of antibiotics that all healthcare workers should consistently adhere in clinical practice.

Bacterial Etiology of Fever Episodes of Splenectomized Patients in Three Medical Centers in the City of Mashhad in Northeastern Iran

Background: Many medical and surgical conditions may need to be treated with splenectomy. As this lymphoid tissue plays an important role in controlling various infections, and many life-threatening infections can occur in the absence of the spleen, any episode of fever should be taken seriously. Objectives: This study aims to assess the bacterial etiology of fever episodes in splenectomized patients in three medical centers in Mashhad, a city in northeastern Iran. Methods: Between 2006 and 2017, splenectomized patients in Imam Reza, Ghaem, and Dr. Sheikh hospitals were included in a cross-sectional study. Data collected included, age at splenectomy, hospitalization duration, indications for admission to the intensive care unit, vital signs at admission, bacterial species responsible for sepsis, times of hospitalization due to fever episodes, clinical signs and symptoms, antibiotic prophylaxis, and outcomes at six and one years. The data were analyzed using SPSS Statistics 20. Results: A total of 280 splenectomized patients were reviewed, and 23 of them had episodes of fever. The most common causes of splenectomy were spleen masses and idiopathic thrombocytopenic purpura (ITP), each accounting for 17.4% of cases. The mean age of the patients was 24.2 ± 1.6 years. 47.8% of the patients were male, and 52.2% were female. The median admission duration was seven days. A majority of admissions were due to intra-abdominal infections (26.7%), pneumonia (13.3%), and bacteremia (10.0%). There were 30 episodes of fever recorded, of which 2 (6.7%) resulted in death. Blood culture was positive in four cases (13.3%) for Streptococcus pneumoniae, Staphylococcus aureus, Citrobacter, and Brucella. A suitable antibiotic coverage was obtained in 13.3% of cases (i.e., ceftriaxone + vancomycin or fluoroquinolone + vancomycin), and a minimum suitable empiric coverage was obtained in 10.0% of cases, and no appropriate antibiotic coverage was obtained in 76.7% of cases. Conclusions: The present study highlights widespread inappropriate empiric therapy of fever episodes in splenectomized patients, as well as a lack of due attention to timely sample collection before antibiotic administration. Despite this, the isolated organisms were varied and included S. pneumoniae, S. aureus, coagulase negative staphylococci, P. aeruginosa, Brucella, and Citrobacter.

Role of Partial Splenectomy in Hematologic Childhood Disorders

The spleen is a secondary lymphoid organ that belongs to the reticular-endothelial system, directly connected to blood circulation. The spleen is greatly involved in the immune response, especially against capsulated bacteria. Splenectomy plays a fundamental role in the treatment of numerous pediatric hematologic disorders. Taking into account all the possible complications (especially infections) linked to this procedure, alternatives to total splenectomy have been sought. Partial splenectomy has been proposed as a treatment that allows the reduction of infectious risk. This approach has proven safe and feasible in most patients, but multicentric and prospective studies are necessary to more accurately define the indications for performing partial splenectomy. However, vaccinations and antibiotic prophylaxis remain fundamental for preventing serious infections, even in the case of partial splenectomy. We review anatomical and functional properties of the spleen, with a focus on medical or surgical indications to splenectomy, aiming to give practical educational information to patients and their families after splenectomy. Furthermore, we discuss the feasibility of partial splenectomy in children with hematologic diseases who require splenectomy.

Pneumococcal vaccine coverage in Japan among patients with a history of splenectomy: Results of a retrospective administrative database study

BACKGROUND

Splenectomy results in immune deficiency and increases the risk of clinically significant infections, termed overwhelming post-splenectomy infection (OPSI). In Japan, vaccination with the 23-valent pneumococcal polysaccharide vaccine (PPSV23) is covered by the Japanese National Health Insurance (NHI) for post-splenectomy patients, but there are limited data about whether these patients receive PPSV23 vaccination.

METHODS

We performed retrospective analyses of the JMDC Claims Database comprising employees (including some retired individuals) and their families in Japan. We identified patients who underwent splenectomy (registration period: January 1, 2005-June 30, 2019) at ≥ 2 to ≤ 64 years old, and obtained information about PPSV23 vaccination, reasons for splenectomy, and prevalence/complications of pneumococcal infectious diseases (including OPSI-related disorders).

RESULTS

Among 7,394,182 registered individuals, splenectomy was performed in 475, with an incidence rate of 1.6 cases per 100,000 person-years. Of 414 patients who underwent splenectomy at ≥ 2 to ≤ 64 years of age, their mean ± standard deviation age was 45.4 ± 15.7 years and 63.3% were 45-64 years old. Splenectomy was incidental in 55.3%. Overall, 123/414 patients were prescribed PPSV23 vaccination, resulting in vaccination coverage of 29.7%. The median interval from splenectomy to vaccination was 1.0 month (range: -1 to 85 months).

CONCLUSION

This was the first study to document PPSV23 vaccination coverage after splenectomy in a Japanese real-world setting. PPSV23 coverage is quite low in Japan relative to that in other countries.

Immunization coverage among asplenic patients and strategies to increase vaccination compliance: a systematic review and meta-analysis

BACKGROUND

Asplenic or splenectomized patients have a higher risk (ranging from 10 to 50-fold) than the general population of developing an overwhelming post-splenectomy infection (OPSI). Thus, they should receive specific vaccinations to prevent bacterial infections and influenza. The aim of this meta-analysis was to estimate vaccination coverage (VC) with the recommended vaccines among splenectomized patients; strategies recommended in those studies to improve VC worldwide are considered as well.

RESEARCH DESIGN AND METHODS

Scopus, MEDLINE/PubMed, Google Scholar and ISI Web of Knowledge databases were searched. Research papers, short reports, reviews, and meta-analyses published between January 1, 2010 and July 18, 2020 were included; no geographic restrictions were included. Twenty-four studies were included in the meta-analysis.

RESULTS

For anti-pneumococcal vaccination, coverage was 55.1% (95%CI = 41.0-69.2%), for anti-Hib 48.3% (95%CI = 34.3-52.3%), for anti-meningococcal C/ACYW135 33.7% (95%CI = 23.6-43.9%), for anti-meningococcal B 13.3% (95%CI = 7.0-19.5%) and for anti-influenza 53.2% (95%CI = 22.0-84.4%). Most studies determined a lack of adherence to international guidelines by healthcare workers and suggested the need to better educate health professionals in the management of post-splenectomy patients.

CONCLUSIONS

The meta-analysis showed the suboptimal immunization coverage for the vaccines recommended for asplenic patients. Greater efforts must be made by public health professionals to increase VC in this group of patients at risk. Introducing specific prophylaxis protocols in the clinical routine seems to guarantee better immunization compliance in those patients.

Readmission for infection after blunt splenic injury: A national comparison of management techniques

BACKGROUND

As nonoperative management (NOM) of blunt splenic injury (BSI) increases, understanding risks, especially infectious complications, becomes more important. There are no national studies on BSI outcomes that track readmissions across hospitals. Prior studies demonstrate that infection is a major cause of readmission after trauma and that a significant proportion is readmitted to different hospitals. The purpose of this study was to compare nationwide outcomes of different treatment modalities for BSI including readmissions to different hospitals.

METHODS

The Nationwide Readmissions Database for 2010 to 2014 was queried for patients 18 years to 64 years old admitted nonelectively with a primary diagnosis of BSI. Organ space infection; a composite infectious incidence of surgical site infection (SSI), urinary tract infection, and pneumonia; and sepsis were identified in three groups: NOM, splenic artery embolization (SAE), and operative management (OM). Rates of infection were quantified during index admission and 30-day and 1-year readmission. Multivariable logistic regression was performed. Results were weighted for national estimates.

RESULTS

Of the 37,986 patients admitted for BSI, 54.1% underwent NOM, 12.2% SAE, and 33.7% OM. Compared with OM and NOM, SAE had the highest rates of organ space SSI at 1 year (3.9% vs. 2.2% vs. 1.7%, p < 0.001). Compared with NOM, at 1 year, SAE had higher rates of infection (17.2% vs. 8.1%, p < 0.001) and sepsis (3.2% vs. 1.1%, p < 0.001). Compared with NOM, SAE had an increased risk of infection (odds ratio [OR], 1.24; 95 confidence interval [95% CI], 1.10-1.39; p < 0.001) and sepsis (OR, 1.37; 95% CI, 1.06-1.76; p < 0.001) at 1 year. At 1 year, SAE had increased risk of organ space SSI (OR, 1.99; 1.60-2.47; p < 0.001) but OM did not.

CONCLUSION

Blunt splenic injury treated with SAE is at increased risk of both immediate and long-term infectious complications. Despite being considered splenic preservation, surgeons should be aware of these risks and incorporate such knowledge into their practice accordingly.

LEVEL OF EVIDENCE

Epidemiological study, level IV.

Disparities in the management of paediatric splenic injury

BACKGROUND

The non-operative management of splenic injury in children is recommended widely, and is possible in over 95 per cent of episodes. Practice appears to vary between centres.

METHODS

The Trauma Audit and Research Network (TARN) database was interrogated to determine the management of isolated paediatric splenic injuries in hospitals in England and Wales. Rates of non-operative management, duration of hospital stay, readmission and mortality were recorded. Management in paediatric surgical hospitals was compared with that in adult hospitals.

RESULTS

Between January 2000 and December 2015 there were 574 episodes. Children treated in a paediatric surgical hospital had a 95·7 per cent rate of non-operative management, compared with 75·5 per cent in an adult hospital (P < 0·001). Splenectomy was done in 2·3 per cent of children in hospitals with a paediatric surgeon and in 17·2 per cent of those treated in an adult hospital (P < 0·001). There was a significant difference in the rate of non-operative management in children of all ages. There was some improvement in non-operative management in adult hospitals in the later part of the study, but significant ongoing differences remained.

CONCLUSION

The management of children with isolated splenic injury is different depending on where they are treated. The rate of non-operative management is lower in hospitals without a paediatric surgeon present.

Structure-Function Relationships of the Neisserial EptA Enzyme Responsible for Phosphoethanolamine Decoration of Lipid A: Rationale for Drug Targeting

Bacteria cause disease by two general mechanisms: the action of their toxins on host cells and induction of a pro-inflammatory response that can lead to a deleterious cytokine/chemokine response (e.g., the so-called cytokine storm) often seen in bacteremia/septicemia. These major mechanisms may overlap due to the action of surface structures that can have direct and indirect actions on phagocytic or non-phagocytic cells. In this respect, the lipid A (endotoxin) component of lipopolysaccharide (LPS) possessed by Gram-negative bacteria has been the subject of literally thousands of studies over the past century that clearly identified it as a key virulence factor in endotoxic shock. In addition to its capacity to modulate inflammatory responses, endotoxin can also modulate bacterial susceptibility to host antimicrobials, such as the host defense peptides termed cationic antimicrobial peptides. This review concentrates on the phosphoethanolamine (PEA) decoration of lipid A in the pathogenic species of the genus Neisseria [N. gonorrhoeae and N. meningitidis]. PEA decoration of lipid A is mediated by the enzyme EptA (formerly termed LptA) and promotes resistance to innate defense systems, induces the pro-inflammatory response and can influence the in vivo fitness of bacteria during infection. These important biological properties have driven efforts dealing with the biochemistry and structural biology of EptA that will facilitate the development of potential inhibitors that block PEA addition to lipid A.

Should splenic autotransplantation be considered after total splenectomy due to trauma?

Trauma is a public health problem and the most common cause of death in people under the age of 45. In blunt abdominal trauma, the spleen is the most commonly injured organ. Splenectomy remains the most common treatment, especially in high-grade lesions, despite increased nonoperative treatment. Removal of the spleen leads to increased susceptibility to infections due to its role in the immune function. Postsplenectomy sepsis is an important complication and presents a high mortality rate. Patients undergoing splenectomy should be immunized for encapsulated germs, as these are the agents most commonly associated with such infections. Splenic autotransplantation is a simple procedure, which can be an alternative to reduce infection rates consequent to total splenectomy, and reduce costs related to hospitalizations. This review aims to provide evidence-based information on splenic autotransplantation and its impact on the prognosis of patients undergoing total splenectomy. We searched the Cochrane Library, Medline/PubMed, SciELO and Embase, from January 2017 to January 2018 and selected articles in English and Portuguese, dated from 1919 to 2017. We found that the adjusted risk of death in splenectomized patients is greater than that of the general population, and when total splenectomy is performed, splenic autotransplantation is the only method capable of preserving splenic function, avoiding infections, especially postsplenectomy sepsis. Health professionals should be familiar with the consequences of the method chosen to manage the patient suffering from splenic trauma.

Pathogen clearance and immune adherence "revisited": Immuno-regulatory roles for CRIg

Rapid elimination of microbes from the bloodstream, along with the ability to mount an adaptive immune response, are essential for optimal host-defense. Kupffer cells are strategically positioned in the liver sinusoids and efficiently capture circulating microbes from the hepatic artery and portal vein, thus preventing bacterial dissemination. In vivo and in vitro studies have probed how complement receptor of the immunoglobulin superfamily (CRIg), also referred to as Z39Ig and V-set and Ig domain-containing 4 (VSIG4), acts as a critical player in pathogen recognition and clearance. While recent data suggested that CRIg may bind bacterial cell wall components directly, the single transmembrane receptor is best known for its interaction with complement C3 opsonization products on the microbial surface. On Kupffer cells, CRIg must capture opsonized microbes against the shear forces of the blood flow. In vivo work reveals how immune adherence (IA), a process in which blood platelets or erythrocytes associate with circulating bacteria, plays a critical role in regulating pathogen capture by CRIg under flow conditions. In addition to its typical innate immune functions, CRIg was shown to directly and indirectly influence adaptive immune responses. Here, we review our current understanding of the diverse roles of CRIg in pathogen elimination, anti-microbial immunity and autoimmunity. In particular, we will explore how, through selective capturing by CRIg, an important balance is achieved between the immunological and clearance functions of liver and spleen.

Postsplenectomy vaccination guideline adherence: Opportunities for improvement

BACKGROUND AND PURPOSE

Patients undergoing splenectomy for trauma are at life-long risk for rapidly progressive septicemia. The purpose of this study was to investigate long-term patient understanding and follow-up with recommendations regarding their asplenia.

METHODS

Patients undergoing splenectomy for trauma January 2010-December 2014 were analyzed. Medical records were reviewed and telephone follow-up interviews were conducted in October-December 2015. Patients were asked a standard set of questions that included hospitalizations, awareness of infectious risks associated with asplenia, need for revaccination, and vaccines they had received since their index hospitalization.

FINDINGS

Two hundred forty-four patients underwent splenectomy during the study period. A total of 95 patients (39%) were included in the study. Thirty (32%) had been hospitalized since their trauma admission. Only 46% were aware of the risks for sepsis and the need to revaccinate. Only 7% reported having rapid access to antibiotics.

CONCLUSIONS

Despite uniform education prior to discharge, most patients undergoing splenectomy for trauma were unaware of the risks for sepsis and did not follow recommended guidelines for risk reduction.

IMPLICATIONS FOR PRACTICE

Improvements that have direct implications for advanced practice included the need to refer for vaccination, educate regarding infection risks, and facilitate rapid access to antibiotic treatment.