A case of functional asplenia and pneumococcal sepsis

Streptococcus pneumoniae Infection in Patients with Asplenia: A Spanish Perspective over a 25-Year Period

Anatomical or functional asplenia constitutes a risk factor for Streptococcus pneumoniae (SP) infection, being more frequent in children and the elderly and in people with multiple comorbidities. We aimed to describe the impact of invasive pneumococcal disease (IPD) on the clinical features and outcomes of patients hospitalized for asplenia in Spain. Discharge reports from the Spanish Minimum Basic Data Set were used to retrospectively analyze hospital discharge data with a diagnosis of asplenia from 1997 to 2021. A total of 132,257 patients with asplenia (splenectomized/non-splenectomized) were identified from the Spanish database. Among the cases, 177 (37.5%) patients with splenectomy and 295 (62.5%) patients without splenectomy developed IPD. The clinical presentations (non-infection vs. infection) did not significantly differ between the two reference groups, except for patients with COPD, rheumatoid disease, AIDS, other neurological disorders, metastatic cancer, and drug abuse. The risk factors for IPD were also more frequently reported in patients without splenectomy (p < 0.001) and with comorbidities (p = 0.005). The study of patients with asplenia provides relevant information about the state of SP infection. This epidemiological tracking can serve to better understand the comorbidities that affect them, the risk factors for the disease, the prediction of antibiotic use, and vaccination in public health, among other factors.

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.

Immunodeficiency among children with recurrent invasive pneumococcal disease

BACKGROUND

Recurrent invasive pneumococcal disease (rIPD) occurs mostly in children with an underlying disease, but some cases remain unexplained. Immunodeficiency has been described in children with rIPD, but the prevalence is unknown. We used a nationwide registry of all laboratory-confirmed cases of rIPD to identify cases of unexplained rIPD and examine them for immunodeficiency.

METHODS

Cases of rIPD in children 0-15 years of age from 1980 to 2008 were identified. Children without an obvious underlying disease were screened for complement function, T-cell, B-cell, natural killer--cell counts and concentration of immunoglobulins. B-cell function was evaluated by measuring antibody response to polysaccharide-based pneumococcal vaccination and the extent of fraction of somatic hypermutation. Toll-Like receptor (TLR) signaling function and mutations in key TLR-signaling molecules were examined.

RESULTS

In total, rIPD were observed in 54 children (68 cases of rIPD of 2192 IPD cases). Children with classical risk factors for IPD were excluded, and among the remaining 22 children, 15 were eligible for analysis. Of these 6 (40%) were complement C2-deficient. Impaired vaccination response was found in 6 children of whom 3 were C2 deficient. One patient had a severe TLR signaling dysfunction. No mutations in IRAK4, IKBKG or MYD88 were found.

CONCLUSION

Of an unselected cohort of children with rIPD at least 11% were C2 deficient. Data suggest that screening for complement deficiencies and deficient antibody response to pneumococcal vaccines in patients with more than 1 episode of IPD is warranted.

Plasmodium falciparum malaria and invasive bacterial co-infection in young African children: the dysfunctional spleen hypothesis

Children with recent or acute malaria episodes are at increased risk of invasive bacterial infections (IBI). However, the exact nature of the malaria-IBI association is still unclear. Young children have an age-related spleen immunologic immaturity, mainly due to the still ongoing development of the marginal zone (MZ) B cell subset. By mounting a rapid antibody response against encapsulated bacteria, these cells are critical for the defence against highly pathogenic microorganisms that do not elicit classical T cell-dependent responses. There is increasing evidence that the anatomy of the spleen becomes disorganized during malaria infection, with complete dissolution of the MZ and apoptosis of MZ B cells. Correspondingly, a reduction in the frequency of the peripheral equivalent of the MZ B cells has been found in malaria endemic areas. A remarkable similarity exists in IBI susceptibility between African children with malaria and hyposplenic or splenectomized patients. However, studies specifically assessing the immune function of the spleen in controlling bacterial infections in young children with malaria are scarce.

Here, it is hypothesized that Plasmodium falciparum malaria infection constitutes a detrimental factor in the still immature spleen function of young children, resulting in a factually hyposplenic state during malaria episodes, putting children with malaria at a high risk to develop life-threatening bacterial infections. Studies to confirm or reject this hypothesis are greatly needed, as well as the development of affordable and feasible tools to assess the immune spleen function against encapsulated bacteria in children with malaria.