Vaccination rates among adults with sickle cell disease: a single-center study from the Eastern Mediterranean region of Turkey

Objective: Being vaccinated against encapsulated bacteria is the most efficient way to reduce painful crises and mortality in patients with sickle cell disease (SCD). Although guidelines strongly recommend vaccination, vaccination rates remain under the desired levels. In this study, we aim to determine vaccination rates and understand the reasons for non-vaccination in patients with SCD. Material and methods: We included 76 patients with SCD in this study. We administered a questionnaire consisting of 21 questions and examined the electronic vaccination records of these patients. Results: The vaccination rates were 36.5% for the pneumococcal vaccine, 22.4% for the Hemophilus influenza type b vaccine, and 19.7% for the meningococcal vaccine. Residence in rural areas and annual control visits were found to increase the pneumococcal vaccination rates (OR: 11.90, 95% CI: 2.549–56.107, p = 0.002 and OR: 9.08, 95% CI: 1.120–73.624, p = 0.039, respectively) and meningococcal vaccination rates (OR: 2.75, 95% CI: 1.464–5.186, p = 0.002 and OR:1.36, 95% CI: 1.159–1.610, p < 0.001, respectively). Thirty-four (44.7%) of the cases stated that their doctors did not give any information about these vaccinations. Conclusion: Vaccination rates are low in patients with SCD. Residence in rural areas, annual control visits, educational level, and doctor recommendations affect these vaccination rates.

Vaccine Types

Vaccines are biological preparations, often made from attenuated or killed forms of microorganisms or fractions thereof. They work by stimulating the immune system to produce antibodies and cells directed against a particular organism, mimicking "natural infection". Based on their biological and chemical characteristics, vaccines can be categorized into two basic types, "Live-attenuated" (bacterial or viral) vaccines and "inactivated" or "non-live" vaccines. Examples of live-attenuated vaccines include: measles-, mumps-, and rubella-, varicella-, yellow fever-, oral polio- (OPV), rotavirus-, ("nasal-spray") live-attenuated influenza- (LAIV), and BCG-vaccine. Attenuation results in micro-organisms that may still infect and multiply in humans, but they do not cause disease. Some of these vaccines are associated with life-long immunity. Inactivated or non-live vaccines include those against hepatitis A, influenza, pertussis, rabies or the polysaccharide vaccines directed against encapsulated bacteria (Haemophilus influenzae type b, Streptococcus pneumoniae, Neisseria meningitidis). Most non-live vaccines generally require additional doses ("boosters") to maintain long-term protective immunity. There are many other subcategories of these basic groups, like subunit vaccines, whole cell vaccines, toxoid vaccines, polysaccharide vaccines, recombinant protein vaccines, mucosal vaccines, or DNA-, mRNA- and vector-vaccines.

Alternative Complement Pathway Inhibition Does Not Abrogate Meningococcal Killing by Serum of Vaccinated Individuals

Dysregulation of complement activation causes a number of diseases, including paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome. These conditions can be treated with monoclonal antibodies (mAbs) that bind to the complement component C5 and prevent formation of the membrane attack complex (MAC). While MAC is involved in uncontrolled lysis of erythrocytes in these patients, it is also required for serum bactericidal activity (SBA), i.e. clearance of encapsulated bacteria. Therefore, terminal complement blockage in these patients increases the risk of invasive disease by Neisseria meningitidis more than 1000-fold compared to the general population, despite obligatory vaccination. It is assumed that alternative instead of terminal pathway inhibition reduces the risk of meningococcal disease in vaccinated individuals. To address this, we investigated the SBA with alternative pathway inhibitors. Serum was collected from adults before and after vaccination with a meningococcal serogroup A, C, W, Y capsule conjugate vaccine and tested for meningococcal killing in the presence of factor B and D, C3, C5 and MASP-2 inhibitors. B meningococci were not included in this study since the immune response against protein-based vaccines is more complex. Unsurprisingly, inhibition of C5 abrogated killing of meningococci by all sera. In contrast, both factor B and D inhibitors affected meningococcal killing in sera from individuals with low, but not with high bactericidal anti-capsular titers. While the anti-MASP-2 mAb did not impair SBA, inhibition of C3 impeded meningococcal killing in most, but not in all sera. These data provide evidence that vaccination can provide protection against invasive meningococcal disease in patients treated with alternative pathway inhibitors.

Effect of Direct Viral–Bacterial Interactions on the Removal of Norovirus From Lettuce

Norovirus (NoV) is the main non-bacterial pathogen causing outbreaks of gastroenteritis and is considered to be the leading cause of foodborne illness. This study aims to determine whether lettuce-encapsulated bacteria can express histo-blood group antigen (HBGA)–like substances to bind to NoV and, if so, to explore its role in protecting NoV from disinfection practices. Fifteen bacterial strains (HBGA-SEBs) were isolated from the lettuce microbiome and studied as they were proved to have the ability to express HBGA-like substances through indirect ELISA detection. By using attachment assay, HBGA-SEBs showed great abilities in carrying NoVs regarding the evaluation of binding capacity, especially for the top four strains from genera Wautersiella, Sphingobacterium, and Brachybacterium, which could absorb more than 60% of free-flowing NoVs. Meanwhile, the direct viral–bacterial binding between HBGA-like substance-expressing bacteria (HBGA-SEB) and NoVs was observed by TEM. Subsequently, results of simulated environmental experiments showed that the binding of NoVs with HBGA-SEBs did have detrimental effects on NoV reduction, which were evident in short-time high-temperature treatment (90°C) and UV exposure. Finally, by considering the relative abundance of homologous microorganisms of HBGA-SEBs in the lettuce microbiome (ca. 36.49%) and the reduction of NoVs in the simulated environments, we suggested putting extra attention on the daily disinfection of foodborne-pathogen carriers to overcome the detrimental effects of direct viral–bacterial interactions on the reduction of NoVs.

Evaluating Functional Immunity Following Encapsulated Bacterial Infection and Vaccination

Encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae type b and Neisseria meningitidis cause significant morbidity and mortality in young children despite the availability of vaccines. Highly specific antibodies are the primary mechanism of protection against invasive disease. Robust and standardised assays that measure functional antibodies are also necessary for vaccine evaluation and allow for the accurate comparison of data between clinical studies. This mini review describes the current state of functional antibody assays and their importance in measuring protective immunity.

Coating Lacticaseibacillus rhamnosus GG in Alginate Systems: an Emerging Strategy Towards Improved Viability in Orange Juice

Fruit juices are successfully proposed as suitable probiotic vehicles, but researchers’ efforts should be developed to avoid effects of bacteria overgrowing on sensory and nutritional cues of final products and to preserve viability of probiotic bacteria during storage. In the present study, encapsulation of Lacticaseibacillus rhamnosus GG strain in alginate systems was performed through ionotropic gelation technology. The alginate systems were optimized by using Box-Behnken Design to investigate the influence of three independent variables at three different levels: particle mean size and polydispersity index. The optimized probiotic-loaded alginate particles were added to orange juice samples. The viability of the probiotic strain, both as free and microencapsulated, was evaluated in orange juice stored at 5°C for 35 days. Morphology and size of probiotic-loaded alginate particles were found suitable for incorporation into juice. TEM analysis revealed that unloaded systems were clustered as nanoparticles (CL_NP), while the loaded sample appeared as a coated system (Coated_LGG). Microbiological evaluation revealed that the encapsulation assured the survival of Coated_LGG, with a reduction of less than 1-unit log in cellular density after 35 days of refrigerated storage in orange juice. Results indicated that the encapsulated bacteria did not affect the macroscopic properties neither the microbiological characteristic of orange juice; thus, it can be proposed as functional food.

Interfacial Interactions between Protective, Surface-Engineered Shells and Encapsulated Bacteria with Different Cell Surface Composition

Surface-engineered encapsulation is a non-genetic method to protect living organisms against harsh environmental conditions. Different cell encapsulation methods exist, yielding shells with different interfacial-interactions with encapsulated, bacterial surfaces. However, the...

Vaccination Rates and Adherence to Guidelines in Splenectomy Patients: An Observational Cross-sectional Study

Introduction: Splenectomy, whatever the reason, is an absolute indication for vaccination against encapsulated bacteria in order to prevent overwhelming post-splenectomy infections. This study aimed to determine compliance to immunization guidelines for splenectomy in General Surgery Clinics. Materials and Methods: In this observational cross-sectional study, we included patients who underwent splenectomy between April 2016 and April 2018, and recorded the patient data and vaccination status. Results: Splenectomy was performed in 65 patients, 40 (61.5%) were male and median age was 56 (19-90) years. Six of the operations were emergent, 21 were planned and 38 were urgent mostly due to solid organ malignancy. Only 14 (21.5%) patients were vaccinated with Haemophilus influenzae, meningococcal and pneumococcal vaccines according to the guidelines (≥2 weeks before the operation). 14 of the 21 patients (66.6%) who underwent planned splenectomy were vaccinated appropriately. Conclusion: Compliance with vaccination guidelines was low before splenectomy operations. There is a room for improvement particularly for patients undergoing elective splenectomy. A patient-centered team strategy is required to vaccinate patients at the stage of splenectomy planning.