NORMAL RESPONSE OF SICKLE CELL ANEMIA PATIENTS TO IMMUNIZATION WITH SALMONELLA VACCINES

Utilization, financial outcomes and stakeholder perspectives of a re-organized adult sickle cell program

In 2011 Yale New Haven Hospital, in response to high utilization of acute care services and widespread patient and health care personnel dissatisfaction, set out to improve its care of adults living with sickle cell disease. Re-organization components included recruitment of additional personnel; re-locating inpatients to a single nursing unit; reducing the number of involved providers; personalized care plans for pain management; setting limits upon access to parenteral opioids; and an emphasis upon clinic visits focused upon home management of pain as well as specialty and primary care. Outcomes included dramatic reductions in inpatient days (79%), emergency department visits (63%), and hospitalizations (53%); an increase in outpatient visits (31%); and a decrease in costs (49%). Providers and nurses viewed the re-organization and outcomes positively. Most patients reported improvements in pain control and life style; many patients thought the re-organization process was unfair. Their primary complaint was a lack of shared decision-making. We attribute the contrast in these perspectives to the inherent difficulties of managing recurrent acute and chronic pain with opioids, especially within the context of the imbalance in wellness, power, and privilege between persons living with sickle cell disease, predominantly persons of color and poor socio-economic status, and health care organizations and their personnel.

Pathogenic signature of invasive non-typhoidal Salmonella in Africa: implications for vaccine development

Invasive non-typhoidal Salmonella (iNTS) infections are a leading cause of bacteremia in Sub-Saharan Africa (sSA), thereby representing a major public health threat. Salmonella Typhimurium clade ST313 and Salmonella Enteriditis lineages associated with Western and Central/Eastern Africa are among the iNTS serovars which are of the greatest concern due to their case-fatality rate, especially in children and in the immunocompromised population. Identification of pathogen-associated features and host susceptibility factors that increase the risk for invasive non-typhoidal salmonellosis would be instrumental for the design of targeted prevention strategies, which are urgently needed given the increasing spread of multidrug-resistant iNTS in Africa. This review summarizes current knowledge of bacterial traits and host immune responses associated with iNTS infections in sSA, then discusses how this knowledge can guide vaccine development while providing a summary of vaccine candidates in preclinical and early clinical development.

Salmonella osteomyelitis and arthritis in sickle cell disease

Salmonellosis is one of the most frequent serious infections in sickle cell patients and remains a significant cause of morbidity and mortality in this population. Capillary occlusion secondary to intravascular sickling may devitalize and infarct the gut, permitting Salmonella invasion. Reduced function of the liver and spleen, together with interference with reticuloendothelial system function due to erythrophagocytosis, suppresses clearing of these organisms from the blood stream. Abnormal opsonizing and complement function probably also play a role. The expanded bone marrow with sluggish flow leads to an ischemic focus for salmonella localization. The majority of Salmonella infections in sickle cell patients involve bones (especially long bones) and joints and occur most frequently in early childhood. Multiple sites, often symmetrical, are usually involved. It is imperative to distinguish Salmonella osteomyelitis from bone infarctions. While clinical and hematologic data may be suggestive, radionuclide bone imaging studies, particularly combined technetium and gallium scintigraphy and technetium sulphur colloid bone marrow scans, and magnetic resonance imaging appear more sensitive and specific. Salmonella osteomyelitis is best managed medically. Chloramphenicol, ampicillin, and trimethoprim/sulfamethoxazole have been used most frequently; however, newer beta lactams and quinolones are more active. Septic arthritis carries a poorer prognosis and often requires aggressive surgical intervention.

Impaired IgM antibody responses to an influenza virus vaccine in adults with sickle cell anemia

Type-specific IgM and IgG antibody responses to a polyvalent influenza vaccine were evaluated in 16 adults with sickle cell anemia, with the use of an enzyme-linked immunosorbent assay. When compared to healthy controls, 8 out of the 16 patients had decreased or undetectable postvaccination anti-influenza IgM antibody levels. These patients were found to have significantly lower serum IgM levels and nondetectable splenic tissue (by 99Tc scans), as compared to those with normal IgM responses. Impaired IgM antibody primary immune responses may play a role in the pathogenesis of infectious complications seen in adult patients with sickle cell anemia.

Sickle cell disease and infection

Overwhelming infections caused by encapsulated bacteria, salmonella spp. and Plasmodium falciparum (in malarious areas) are an important cause of morbidity and death in patients with sickle cell disease. Bacterial infections afflicting these patients include fulminant meningitis and septicaemia caused by Str. pneumoniae and H. influenzae type b, and non-typhoid salmonellosis. Children less than five years of age are at greatest risk for meningitis and septicaemia, while salmonella osteomyelitis is probably common to all age groups. The most important contributing factors to this increased susceptibility to encapsulated bacteria are: a state of functional asplenia, an opsonophagocytic defect due to an abnormality of the alternative complement pathway, and a deficiency of specific circulating antibodies. Devitalisation of gut and bone due to repetitive vaso-occlusive crises, saturation of the macrophage system with red cell breakdown products of chronic haemolysis, and underlying splenic and hepatic dysfunction all predispose to salmonella infections. Seventy per cent of septicaemias and meningitis among under-fives with sickle cell disease is caused by Str. pneumoniae. Septicaemia frequently presents with sudden fever, few prodromal features, and a deceptive appearance of well-being, followed within hours by rapid relentless progression to shock and death. Adrenal haemorrhage is common, and mortality can be as high as 50 per cent, unless intravenous antibiotic, with or without steroid therapy, is promptly initiated. The clinical presentation of bacterial meningitis, its management and mortality follow the normal patterns, but recurrent meningitis and cerebrovascular morbidity are common in patients with sickle cell disease. An acute pulmonary involvement, indistinguishable from bacterial pneumonia (the 'chest syndrome') is the commonest single complication of sickle cell disease at any age. Str. pneumoniae is responsible for about half of the episodes. The protective values of the pneumococcal vaccine and long-term penicillin prophylaxis remain to be established in sickle cell disease. Over 70 per cent of haematogenous osteomyelitis in sickle cell disease is caused by salmonellae. The distinction from vaso-occlusive bone crisis is often difficult, but the presence of multiple, often symmetrical bone involvement, diaphyseal fissuring and involucrum should suggest osteomyelitis rather than bone infarction. Chloramphenicol remains the drug of choice and often has to be given in high doses for up to six weeks. The role of surgery is limited by the presence of multiple bone involvement and the known anaesthetic risks in this group.(ABSTRACT TRUNCATED AT 400 WORDS)

Restoration by normal human immunoglobulin G of deficient serum opsonization for Streptococcus pneumoniae in sickle cell disease

Supplementation of sera from four children with sickle cell disease with untreated or heated normal human serum or with normal human immunoglobulin G restored opsonic activity for serotype 10 Streptococcus pneumoniae, whereas supplementation with normal human immunoglobulin M did not.

Salmonella osteomyelitis in childhood. A report of 63 cases seen in Nigerian children of whom 57 had sickle cell anaemia

A review of 63 Nigerian children with salmonella osteomyelitis showed that in all but 2 of them the disease occurred in association with HbS either in the homozygous state (57 patients) or in heterozygous combination with other haemoglobins (4 patients). Osteomyelitis was most prevalent during the first 2 years of life, and boys were more often affected than girls. In the majority, multiple sites were involved and lesions were usually bilateral and often symmetrical. Salmonella sp. was isolated from blood or pus, or both, in all patients. In some patients additional pathogens were also isolated from blood or pus. Clinical presentation was variable. In many patients the illness was slight and they were treated entirely as outpatients, but serious toxaemia, severe bone lesions with pathological fractures, and chronic suppuration occurred in others. Most patients responded well to chloramphenicol and conservative management. There were 4 deaths. 17 patients recovered with sequelae. It is suggested that the peculiar susceptibility of patients with sickle cell anaemia to salmonella osteomyelitis is due to spread of salmonella from the intestine facilitated by devitalisation of gut caused by intravascular sickling, and that infarcts in bone became infected either by transient bacteraemia or by activation of dormant foci of salmonella in bone marrow when tissues are devitalised. It is further suggested that immunological defects in sicklers may impair host response to infection, while haemolysis and hepatic dysfunction, both of which occur in sickle cell anaemia, favour propagation of salmonellae.

Impaired antibody response to pneumococcal vaccine after treatment for Hodgkin's disease

To determine if a normal antibody response can develop after therapy for Hodgkin's disease, we immunized 53 patients and 10 normal controls with dodecavalent pneumococcal vaccine. Antibody concentrations three weeks after immunization (geometric mean of 11 serotypes) were 1566 ng of protein nitrogen per milliliter in controls, 963 ng per milliliter after subtotal radiation (P less than 0.05 compared to controls), 658 ng per milliliter after chemotherapy (P less than 0.05), 377 ng per milliliter after subtotal radiation plus chemotherapy (P less than 0.01) and 283 ng per milliliter after total nodal radiation plus chemotherapy (P less 0.001). Low levels of antibody before immunization correlated with a poor response (r = +0.73, P less than 0.001). The ability to respond to immunization improved significantly but did not return to normal as long as four years after combined therapy. The antibody response to pneumococcal vaccine is profoundly impaired in patients who have received intensive treatment for Hodgkin's disease: the ability of this vaccine to protect them from overwhelming postsplenectomy infections remains in doubt.

Polyvalent pneumococcal-polysaccharide immunization of patients with sickle-cell anemia and patients with splenectomy

To reduce the risk of infection from Streptococcus pneumoniae in hyposplenic patients we administered octavalent pneumococcal vaccine to 77 patients with sickle-cell disease and 19 asplenic persons and compared their response with 82 controls (38 age-matched normal persons and 44 normal black African children). Fifty micrograms each of pneumococcal-polysaccharide Types 1, 3, 6, 7, 14, 18, 19, and 23 were administered subcutaneously. Post-immunization serums (three to four weeks) were available from 52 of 77 patients with sickle-cell disease; the percent responding and the magnitude of the indirect hemagglutination response were comparable to those of the controls. Within two years after immunization we observed eight Str. pneumoniae infections in 106 age-matched unimmunized patients with sickle-cell disease, but none in the 77 immunized (P less than 0.025). We conclude that pneumococcal polysaccharides are immunogenic in hyposplenic patients and may protect against systemic Str. pneumoniae infection.