Sickle cell disease and infection

Recurrent Salmonella bacteraemia and right internal iliac artery endarteritis in a splenectomised patient

A man in his mid-70s with a complex medical history, including splenectomy, presented with fever and rigours. Workup revealed Salmonella enterica serotype typhimurium bacteraemia and right internal iliac artery endarteritis. Two weeks following a 6-week course of antibiotics, he had a recurrence of Salmonella bacteraemia requiring an extended course of treatment.

A Systematic Review of the Diagnosis and Treatment of Non-Typhoid Salmonella Spondylodiscitis in Immunocompetent Children

The aim of this systematic review is to distinguish the clinical features of immunocompetent children with non-typhoid Salmonella spondylodiscitis and summarize the diagnosis, diagnostic tools, and treatment methods to guide clinicians. The review was conducted according to the preferred PRISMA guidelines. We conducted a literature search in the PubMed, Embase, and Cochrane Library databases. Article screening, data extraction, and study evaluation were performed by two independent reviewers. A total of 20 articles, published between 1977 and 2020, were selected, which included 21 patients with average age of 12.76 years (range, 2-18) without comorbidities; in total, 19% of the patients had positive blood cultures for non-typhoid Salmonella, and 80.9% underwent either CT-guided or open biopsy, which were positive for NTS. All infections were monomicrobial, and 11 different serotypes of non-typhoid Salmonella were identified. Analyzing the reviewed cases, 52.4% of the patients presented with fever, 90.5% had localized pain, and only 19% had gastroenteritis. The most common level of discitis was the lumbar region, especially the L4/L5 level. Primarily, third-generation cephalosporin was administered, and antibiotic treatment was given for an average of 9.6 weeks. Non-typhoid Salmonella spondylodiscitis is a rare clinical entity in healthy and immunocompetent children. The identification of the responsible organism is essential to guide antibiotic therapy and define the treatment duration. A significant limiting factor in this systematic review was the lack of published research articles and case series due to the rarity of the disease.

Cutaneous manifestations of sickle cell disease: an updated review

Sickle cell disease is a common and highly morbid genetic condition that is characterized by multi-system involvement, including numerous cutaneous manifestations. Persistent and recurrent leg ulceration has long been considered the dermatological hallmark of those with sickle cell disease, but there have been recent descriptions of associated infection with rare pathogens and episodes of liverdoid vasculopathy. Growing considerations for this population in the literature include cutaneous reactions to common treatments such as hydroxyurea and clinical management of the intersection between sickle cell disease and conditions like plaque psoriasis. Recent studies have also demonstrated an increased resistance to skin carcinogenesis for those with sickle cell disease through unclear mechanisms. However, though the body of knowledge regarding cutaneous manifestations and considerations of sickle cell disease is slowly expanding, it does not match the considerable disease and symptom burden faced by these patients. More research is needed to better delineate our understanding of these cutaneous manifestations of sickle cell disease to improve outcomes and further management.

Heme-stress activated NRF2 skews fate trajectories of bone marrow cells from dendritic cells towards red pulp-like macrophages in hemolytic anemia

Heme is an erythrocyte-derived toxin that drives disease progression in hemolytic anemias, such as sickle cell disease. During hemolysis, specialized bone marrow-derived macrophages with a high heme-metabolism capacity orchestrate disease adaptation by removing damaged erythrocytes and heme-protein complexes from the blood and supporting iron recycling for erythropoiesis. Since chronic heme-stress is noxious for macrophages, erythrophagocytes in the spleen are continuously replenished from bone marrow-derived progenitors. Here, we hypothesized that adaptation to heme stress progressively shifts differentiation trajectories of bone marrow progenitors to expand the capacity of heme-handling monocyte-derived macrophages at the expense of the homeostatic generation of dendritic cells, which emerge from shared myeloid precursors. This heme-induced redirection of differentiation trajectories may contribute to hemolysis-induced secondary immunodeficiency. We performed single-cell RNA-sequencing with directional RNA velocity analysis of GM-CSF-supplemented mouse bone marrow cultures to assess myeloid differentiation under heme stress. We found that heme-activated NRF2 signaling shifted the differentiation of bone marrow cells towards antioxidant, iron-recycling macrophages, suppressing the generation of dendritic cells in heme-exposed bone marrow cultures. Heme eliminated the capacity of GM-CSF-supplemented bone marrow cultures to activate antigen-specific CD4 T cells. The generation of functionally competent dendritic cells was restored by NRF2 loss. The heme-induced phenotype of macrophage expansion with concurrent dendritic cell depletion was reproduced in hemolytic mice with sickle cell disease and spherocytosis and associated with reduced dendritic cell functions in the spleen. Our data provide a novel mechanistic underpinning of hemolytic stress as a driver of hyposplenism-related secondary immunodeficiency.

Profile of bacterial pathogens causing infections in children with sickle cell anaemia in Maiduguri

Background

Sickle cell disease (SCD) is a major cause of morbidity and mortality in African children. Infection has been found to be a major cause of hospitalisation, a major precipitant of crises and one of the greatest causes of death among SCD patients at all ages.

Objectives

The objective of the study was to determine the prevalence of bacterial infection, pattern of the isolates and the antibiotic sensitivity of isolated bacteria among children with sickle cell anaemia (SCA).

Materials and Methods

A cross-sectional study carried out in the University of Maiduguri Teaching Hospital. A total of 242 hospitalised children with SCA with symptoms and signs of infection were recruited for the study using consecutive sampling technique. Sociodemographic and clinical data were obtained. Blood, urine, aspirates, swabs and cerebrospinal fluid samples were collected based on their clinical presentation and subjected to microbiological analysis.

Results

A total of 242 patients were studied. The age range was 9 months-15 years, with a mean age of 6.36 years ± 3.75 years. Male-to-female ratio was 1:1.14, with 41.7% of them belonging to low social class. Seventy seven of the 242 had confirmed bacterial infection giving an incidence of bacterial infection in SCA patients of 31.8%. Gram-negative organisms accounted for 64.5% of the isolates and they include Salmonella, Klebsiella, Escherichia coli and Coliforms. However, Staphylococcus aureus (32.9%) was the most frequent microorganism isolated, followed by Salmonella, (20.3%), Klebsiella (12.6%) and Coliforms (12.6%). Amoxicillin-clavulanate, cefixime and gentamicin showed more than 50% activity against the isolated bacterial pathogens while chloramphenicol was found to have low activity against Salmonella.

Conclusion

High index of suspicion of bacterial infection should be borne in mind of the attending physician when children with SCA present with features of infection. Detailed clinical evaluation and appropriate sample collection for microbiological analysis are recommended. Empirical treatment should be started on SCA patients who have clinical evidence of infection and should be broad enough to cover for common bacterial pathogens.

PET/MRI in paediatric disease

Nuclear medicine and molecular imaging have a small but growing role in the management of paediatric and neonatal diseases. During the past decade, combined PET/MRI has emerged as a clinically important hybrid imaging modality in paediatric medicine due to diagnostic advantages and reduced radiation exposure compared to alternative techniques. The applications for nuclear medicine, radiopharmaceuticals and combined PET/MRI in paediatric diagnosis is broadly similar to adults, however there are some key differences. There are a variety of clinical applications for PET/MRI imaging in children including, but not limited to, oncology, neurology, cardiovascular, infection and chronic inflammatory diseases, and in renal-urological disorders. In this article, we review the applications of PET/MRI in paediatric and neonatal imaging, its current role, advantages and disadvantages over other hybrid imaging techniques such as PET/CT, and its future applications. Overall, PET/MRI is a powerful imaging technology in diagnostic medicine and paediatric diseases. Higher soft tissue contrasts and lower radiation dose of the MRI makes it the superior technology compared to other conventional techniques such as PET/CT or scintigraphy. However, this relatively new hybrid imaging has also some limitations. MRI based attenuation correction remains a challenge and although methodologies have improved significantly in the last decades, most remain under development.

Community based screening for sickle haemoglobin among pregnant women in Benue State, Nigeria: I-Care-to-Know, a Healthy Beginning Initiative

Background

Haemoglobin genotype screening at prenatal care offers women an opportunity to be aware of their genotype, receive education on sickle cell disease (SCD) and may increase maternal demand for SCD newborn screening. In developed countries, most pregnant women who access prenatal care and deliver at the hospital receive haemoglobin genotype screening. In settings with low prenatal care attendance and low hospital deliveries, community-based screening may provide similar opportunity for pregnant women. We assessed the feasibility and acceptability of integrating haemoglobin genotype screening into an existing community-based HIV program.

Methods

Onsite community-based integrated testing for HIV, hepatitis B virus and haemoglobin electrophoresis, were conducted for pregnant women and their male partners. Community Health Advisors implementing the NIH and PEPFAR-supported Healthy Beginning Initiative (HBI) program provided education on SCD, collected blood sample for haemoglobin electrophoresis and provided test results to participants enrolled into the HBI program. We concurrently conducted a cross-sectional study using a pretested, semi-structured, interviewer administered questionnaire to collect demographic data and assess awareness of individual haemoglobin “genotype” among HBI pregnant women participants.

Results

In this study, 99.9% (10,167/10,168) of pregnant women who received education on SCD accepted and completed the survey, had blood drawn for haemoglobin electrophoresis and received their results. A majority of participating pregnant women (97.0%) were not aware of their haemoglobin “genotype”. Among the participants who were incorrect about their haemoglobin “genotype”, 41.1% (23/56) of women who reported their haemoglobin “genotype” as AA were actually AS. The odds of haemoglobin “genotype” awareness was higher among participants who were in younger age group, completed tertiary education, had less number of pregnancies, and attended antenatal care. Overall prevalence of sickle cell trait (AS) was 18.7%.

Conclusions

It is feasible to integrate haemoglobin “genotype” testing into an existing community-based maternal-child program. Most pregnant women who were unaware of their haemoglobin “genotype” accepted and had haemoglobin genotype testing, and received their test results. Increasing parental awareness of their own haemoglobin “genotype” could increase their likelihood of accepting newborn screening for SCD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03974-4.

'Look into Their Hearts' 7-Year-Old Boy with Sickle Cell Disease, Fever, Left Sixth and Seventh Cranial Nerve Palsy and Left Hemiplegia

A 7-year-old Liberian boy presented with fever, severe headache, neck pain and 'not being able to walk'. In the emergency room, his sickle cell screen was positive, and his haemoglobin level was 7 g/dl. Initially, he was admitted to the ward with a diagnosis of sickle cell painful crisis and was treated with ceftrixone iv, and oral morphine and paracetamol. In a more complete physical examination, he had left peripheral seventh nerve palsy, left sixth nerve palsy and ipsilateral hemiplegia, also neck rigidity. In a bedside ultrasound scan, he had a large, mobile vegetation on the aortic leaflet of the mitral valve. The final diagnosis was acute infective endocarditis with multiple embolic strokes in a child with sickle cell disease. Headache and neck rigidity was most likely due to SAH or meningitis.

Streptococcus pneumoniae and Its Virulence Factors H2O2 and Pneumolysin Are Potent Mediators of the Acute Chest Syndrome in Sickle Cell Disease

Sickle cell disease (SCD) is one of the most common autosomal recessive disorders in the world. Due to functional asplenia, a dysfunctional antibody response, antibiotic drug resistance and poor response to immunization, SCD patients have impaired immunity. A leading cause of hospitalization and death in SCD patients is the acute chest syndrome (ACS). This complication is especially manifested upon infection of SCD patients with Streptococcus pneumoniae (Spn)—a facultative anaerobic Gram-positive bacterium that causes lower respiratory tract infections. Spn has developed increased rates of antibiotics resistance and is particularly virulent in SCD patients. The primary defense against Spn is the generation of reactive oxygen species (ROS) during the oxidative burst of neutrophils and macrophages. Paradoxically, Spn itself produces high levels of the ROS hydrogen peroxide (H₂O₂) as a virulence strategy. Apart from H₂O₂, Spn also secretes another virulence factor, i.e., the pore-forming exotoxin pneumolysin (PLY), a potent mediator of lung injury in patients with pneumonia in general and particularly in those with SCD. PLY is released early on in infection either by autolysis or bacterial lysis following the treatment with antibiotics and has a broad range of biological activities. This review will discuss recent findings on the role of pneumococci in ACS pathogenesis and on strategies to counteract the devastating effects of its virulence factors on the lungs in SCD patients.

[Osteoarticular infections in patients with sickle cell disease in Lubumbashi: epidemiological study focusing on etiology and management]

INTRODUCTION

infections are the leading cause of morbidity and mortality in patients with sickle cell disease, especially before age 5 years. The purpose of this study was to highlight the epidemiological features, etiologies and management of osteoarticular infections in patients with sickle cell disease in Lubumbashi.

METHODS

we conducted a descriptive, cross-sectional and retrospective study at the Research Center for Sickle Cell Disease in Lubumbashi (RCSCDL) over a three-year period from June 2014 to June 2017. It included all patients with sickle cell disease on follow up at the RCSCDL who developed osteoarticular infection. Data were obtained from a survey form. Parameters were patient's age, age at first visit, sex, reason for consultation, history, physical signs, diagnosis, paraclinical assessment and treatment.

RESULTS

we identified 35 cases of osteoarticular infections out of a total of 380 cases of sickle-cell disease, reflecting a rate of 9.2%. The most affected age group was people under 5 years of age (37.1%); the average age was 10.9±9.5 years ranging from 8 months and 37 years. There was a slight female predominance (51.4% of cases; sex ratio 1.06 in favor of women). Most patients with osteoarticular infection had a history of transfusion (16.6%) and splenectomy (8.6%). The most common reason for consulting was limb pain (84%); 20 patients (57.1%) had bulbar conjunctival icterus and 26 (74.3%) were pale. Clinical examination showed limb swelling and wound in 27 patients (77.1%) and 19 patients (54.3%), respectively. Clinical palpation of the splenomegaly was performed in 6 patients (17.1%). Three types of osteoarticular infections were detected. They were dominated by osteomyelitis (24 cases; 68.57%) followed by osteitis (7 cases; 20%) and suppurative arthritis (4 cases; 11.43%). Out of 24 cases of osteomyelitis, 18 were acute (75%) and 6 were chronic (25%), of which 4 had a hyperostosing behaviour and 2 a fistulising behaviour. Tibia was the most affected bone (18 cases), X-ray mainly showed osteolysis (27 cases; 77.1%) and then periosteolysis (15 cases; 42.9%). Homozygous sickle cell disease was found in 88.6% of cases. Hemoculture was performed in 17 out the 35 patients and salmonella was isolated in 15 out of 17 cultures (88.23%). Pyoculture was performed in 10 patients; it isolated other germs. Assessment of inflammation was performed in 21 patients: 15 had hyperleukocytosis, 13 pathological white blood cell formula , all had increased sedimentation rate (greater than 20mm in the 1st hour). With respect to immunization schedule, 62.86% of patients received EPI vaccines while patients with sickle cell disease who needed specific vaccine had an adherence rate of 17.14%. With respect to therapy, all of our patients received medical treatment; 6 patients underwent sequestrectomy (17.14%) while the majority of patients (25 cases) underwent orthopedic treatment. Conclusion: bone infection in patients with sickle cell disease is a worryng issue in our poor environment where there isn't a specific vaccine for patients with sickle cell disease.

Vertebral osteomyelitis due to Salmonella Poona in a healthy adolescent female

We present a case of vertebral osteomyelitis in a previously healthy, adolescent Caucasian female athlete. After months of lower back pain, spinal imaging demonstrated phlegmon and suspected osteomyelitis of the L4 vertebral body. A bone biopsy was obtained, and microbiologic cultures yielded pure growth of Salmonella enterica subsp. enterica serovar Poona (S. Poona), a member of the nontyphoid Salmonella group associated with food-borne gastroenteritis in the United States. This case represents the first reported association of S. Poona with osteomyelitis and is interesting in that the infection developed in a patient without traditional risk factors for invasive Salmonella disease (i.e. sickle cell disease). This case highlights the importance of keeping a broad differential diagnosis for lower back pain and emphasizes the value of obtaining specimens for microbiologic culture to aid in diagnosing non-traditional and potentially emerging bacterial pathogens.

Predictors of musculoskeletal manifestations in paediatric patients presenting with sickle cell disease at a tertiary teaching hospital in Lusaka, Zambia

Aims

Sickle cell disease (SCD) is an autosomal recessive inherited condition that presents with a number of clinical manifestations that include musculoskeletal manifestations (MM). MM may present differently in different individuals and settings and the predictors are not well known. Herein, we aimed at determining the predictors of MM in patients with SCD at the University Teaching Hospital, Lusaka, Zambia.

Methods

An unmatched case-control study was conducted between January and May 2019 in children below the age of 16 years. In all, 57 cases and 114 controls were obtained by systematic sampling method. A structured questionnaire was used to collect data. The different MM were identified, staged, and classified according to the Standard Orthopaedic Classification Systems using radiological and laboratory investigations. The data was entered in Epidata version 3.1 and exported to STATA 15 for analysis. Multiple logistic regression was used to determine predictors and predictive margins were used to determine the probability of MM.

Results

The cases were older median age 9.5 (interquartile range (IQR) 7 to 12) years compared to controls 7 (IQR 4 to 11) years; p = 0.003. After multivariate logistic regression, increase in age (adjusted odds ratio (AOR) = 1.2, 95% confidence interval (CI) 1.04 to 1.45; p = 0.043), increase in the frequency of vaso-occlusive crisis (VOC) (AOR = 1.3, 95% CI 1.09 to 1.52; p = 0.009) and increase in percentage of haemoglobin S (HbS) (AOR = 1.18, 95% CI 1.09 to 1.29; p < 0.001) were significant predictors of MM. Predictive margins showed that for a 16-year-old the average probability of having MM would be 51 percentage points higher than that of a two-year-old.

Conclusion

Increase in age, frequency of VOC, and an increase in the percentage of HbS were significant predictors of MM. These predictors maybe useful to clinicians in determining children who are at risk. Cite this article: Bone Joint Open 2020;1-6:175–181.

Predictors of musculoskeletal manifestations in paediatric patients presenting with sickle cell disease at a tertiary teaching hospital in Lusaka, Zambia

AIMS

Sickle cell disease (SCD) is an autosomal recessive inherited condition that presents with a number of clinical manifestations that include musculoskeletal manifestations (MM). MM may present differently in different individuals and settings and the predictors are not well known. Herein, we aimed at determining the predictors of MM in patients with SCD at the University Teaching Hospital, Lusaka, Zambia.

METHODS

An unmatched case-control study was conducted between January and May 2019 in children below the age of 16 years. In all, 57 cases and 114 controls were obtained by systematic sampling method. A structured questionnaire was used to collect data. The different MM were identified, staged, and classified according to the Standard Orthopaedic Classification Systems using radiological and laboratory investigations. The data was entered in Epidata version 3.1 and exported to STATA 15 for analysis. Multiple logistic regression was used to determine predictors and predictive margins were used to determine the probability of MM.

RESULTS

The cases were older median age 9.5 (interquartile range (IQR) 7 to 12) years compared to controls 7 (IQR 4 to 11) years; p = 0.003. After multivariate logistic regression, increase in age (adjusted odds ratio (AOR) = 1.2, 95% confidence interval (CI) 1.04 to 1.45; p = 0.043), increase in the frequency of vaso-occlusive crisis (VOC) (AOR = 1.3, 95% CI 1.09 to 1.52; p = 0.009) and increase in percentage of haemoglobin S (HbS) (AOR = 1.18, 95% CI 1.09 to 1.29; p < 0.001) were significant predictors of MM. Predictive margins showed that for a 16-year-old the average probability of having MM would be 51 percentage points higher than that of a two-year-old.

CONCLUSION

Increase in age, frequency of VOC, and an increase in the percentage of HbS were significant predictors of MM. These predictors maybe useful to clinicians in determining children who are at risk.Cite this article: Bone Joint Open 2020;1-6:175-181.

Life-Threatening Infectious Complications in Sickle Cell Disease: A Concise Narrative Review

Sickle cell disease (SCD) results in chronic hemolytic anemia, recurrent vascular occlusion, insidious vital organ deterioration, early mortality, and diminished quality of life. Life-threatening acute physiologic crises may occur on a background of progressive diminishing vital organ function. Sickle hemoglobin polymerizes in the deoxygenated state, resulting in erythrocyte membrane deformation, vascular occlusion, and hemolysis. Vascular occlusion and increased blood viscosity results in functional asplenia and immune deficiency in early childhood, resulting in life-long increased susceptibility to serious bacterial infections. Infection remains a main cause of overall mortality in patients with SCD in low- and middle-income countries due to increased exposure to pathogens, increased co-morbidities such as malnutrition, lower vaccination rates, and diminished access to definitive care, including antibiotics and blood. Thus, the greatest gains in preventing infection-associated mortality can be achieved by addressing these factors for SCD patients in austere environments. In contrast, in high-income countries, perinatal diagnosis of SCD, antimicrobial prophylaxis, vaccination, aggressive use of antibiotics for febrile episodes, and the availability of contemporary critical care resources have resulted in a significant reduction in deaths from infection; however, chronic organ injury is problematic. All clinicians, regardless of their discipline, who assume the care of SCD patients must understand the importance of infectious disease as a contributor to death and disability. In this concise narrative review, we summarize the data that describes the importance of infectious diseases as a contributor to death and disability in SCD and discuss pathophysiology, prevalent organisms, prevention, management of acute episodes of critical illness, and ongoing care.

Sickle cell disease: Clinical presentation and management of a global health challenge

Sickle cell disease is an autosomal recessive, multisystem disorder, characterised by chronic haemolytic anaemia, painful episodes of vaso-occlusion, progressive organ failure and a reduced life expectancy. Sickle cell disease is the most common monogenetic disease, with millions affected worldwide. In well-resourced countries, comprehensive care programs have increased life expectancy of sickle cell disease patients, with almost all infants surviving into adulthood. Therapeutic options for sickle cell disease patients are however, still scarce. Predictors of sickle cell disease severity and a better understanding of pathophysiology and (epi)genetic modifiers are warranted and could lead to more precise management and treatment. This review provides an extensive summary of the pathophysiology and management of sickle cell disease and encompasses the characteristics, complications and current and future treatment options of the disease.

The challenge of differentiating vaso-occlusive crises from osteomyelitis in children with sickle cell disease and bone pain: A 15-year retrospective review

PURPOSE

The paediatric sickle cell disease (SCD) osteomyelitis (OM) incidence is 0.3% to 12%. Differentiating vaso-occlusive crises (VOC) from OM is a diagnostic challenge, with limited evidence guiding management. We present a 15-year review of a paediatric sickle cell cohort. We aim to identify OM incidence and provide a management protocol for these children presenting with bone pain.

METHODS

A prospective database of children with haemoglobinopathies (2002 to 2017) was analyzed for temperature, C-reactive protein (CRP) and white cell count (WCC) on admission as well as imaging, treatment and cultures. OM diagnosis was supported by imaging and blood cultures. VOC was defined as bone pain that improved without antibiotics.

RESULTS

Over 15 years, 96 children with SCD presented 358 times to hospital. Empirical antibiotics were given in 308 presentations. There were five cases of OM (1.4%); two acute and three chronic. In all, 50 presentations of VOC were identified. No significant differences in age were noted between the OM and VOC group. Temperature and CRP were significantly elevated in the OM group with no significant difference in WCC. Cultures were only positive in the chronic OM admissions. There were no cases of septic arthritis. No surgical intervention was required.

CONCLUSION

In children with SCD presenting with persistent bone pain, fever, elevated CRP and WCC, OM should be suspected and prompt antibiotic treatment started. Our treatment pathway was successful avoiding OM in 98.6% and septic arthritis in 100%. Further research on novel biological markers distinguishing OM from VOC should be investigated.

LEVEL OF EVIDENCE

III.

Significance of electronic health records: A comparative study of vaccination rates in patients with sickle cell disease

OBJECTIVE

In this study, we investigated the influence of electronic health records (EHR) and electronic vaccination schedule applications on the vaccination status of patients who were admitted to our Center for the treatment of sickle cell disease (SCD).

METHODS

The vaccination status against influenza and pneumococcus infection was determined in 93 patients who were admitted to the hematology outpatient clinic, Baskent University Adana Hospital from April 2004 to March 2009. The vaccination status was then re-evaluated following establishment of EHR and electronic vaccination schedules in 2012.

RESULTS

Of the 93 patients with SCD 21.5% (n = 20) were vaccinated against pneumococcus and 21.5% (n = 20) were regularly vaccinated against influenza. When the vaccination rates of 59 of 93 patients who presented for their regular control examinations were analyzed following establishment of EHR and vaccination schedules in 2012, these rates were 49.2% (n = 29) and 50.8% (n = 30) for influenza and pneumococcus, respectively, after EHR; there were 23.7% (n = 14) and 20.3% (n = 12), respectively, before EHR. A statistically significant difference was found between the vaccination rates before and after EHR (p < 0.05).

CONCLUSION

Although viral and bacterial infections are life-threatening health problems in patients with SCD, the vaccination rates were low in high-risk patients. However, these rates increased after application of electronic vaccination schedules.

Nuclear Medicine Imaging in Pediatric Infection or Chronic Inflammatory Diseases

In this review article, we focus on the most recent applications of nuclear medicine techniques (mainly ^99mTc/¹¹¹In white blood cells (WBC) scan, [¹⁸F]-FDG-PET/CT, [¹⁸F]-FDG-PET/MRI, and ^99mTc-IL-2 scintigraphy) in the study of children affected by peripheral bone osteomyelitis, fungal infections, inflammatory bowel diseases, and type 1 diabetes, owing to recent important published evidences of their role in the management of these diseases. For osteomyelitis in children, both bone scintigraphy and [¹⁸F]-FDG-PET have a major advantage of assessing the whole body in one imaging session to confirm or exclude multifocal involvement, whereas WBC scan has a limited role. In children with fungal infections, [¹⁸F]-FDG-PET can help in defining the best location for biopsy and can help in evaluating the extent of the infection and organs involved (also sites that were not yet clinically apparent), although its main role is for therapy monitoring. In inflammatory bowel diseases, and Crohn disease in particular, WBC scan has been successfully used for many years, but it is now used only in case of doubtful magnetic resonance (MR) or when MR cannot be performed and endoscopy is inconclusive. By contrast, there is an accumulating evidence of the role of [¹⁸F]-FDG-PET in management of children with Crohn disease, and PET/MR could be a versatile and innovative hybrid imaging technique that combines the metabolic information of PET with the high soft tissue resolution of MR, particularly for distinguishing fibrotic from active strictures. Finally, there are several new radiopharmaceuticals that specifically target inflammatory cells involved in the pathogenesis of insulitis aiming at developing new specific immunotherapies and to select children candidates to these treatments for improving their quality of life.

Epidemiology and treatment of relative anemia in children with sickle cell disease in sub-Saharan Africa

INTRODUCTION

Sickle cell disease (SCD) is the most common inherited hemoglobinopathy in the world, with the majority of cases in sub-Saharan Africa. Concomitant nutritional deficiencies, infections or exposure to environmental toxins exacerbate chronic anemia in children with SCD. The resulting relative anemia is associated with increased risk of strokes, poor cognitive function and impaired growth. It may also attenuate optimal response to hydroxyurea therapy, the only effective and practical treatment option for SCD in sub-Saharan Africa. This review will focus on the epidemiology, clinical sequelae, and treatment of relative anemia in children with SCD living in low and middle-income countries in sub-Saharan Africa. Areas covered: The causes and treatment of relative anemia in children with SCD in sub-Saharan Africa. The MEDLINE database was searched using medical subject headings (MeSH) and keywords for articles regarding relative anemia in children with SCD in sub-Saharan Africa. Expert commentary: Anemia due to nutritional deficiencies and infectious diseases such as helminthiasis and malaria are prevalent in sub-Saharan Africa. Their co-existence in children with SCD increases morbidity and mortality. Therefore, preventing, diagnosing and treating the underlying cause of this relative anemia will improve SCD-related outcomes in children in sub-Saharan Africa.

Antibody persistence after serogroup C meningococcal conjugate vaccine in children with sickle cell disease

BACKGROUND

A decline of protective antibody titers after MCC vaccine has been demonstrated in healthy children, this may be an issue of concern for risk groups. The aim of this study was to evaluate the persistence of bactericidal antibodies after MCC vaccine in sickle cell disease (SCD) patients. The type of vaccine used and booster response were also analyzed.

METHODS

SCD patients (n=141) previously immunized with MCC vaccines had blood drawn 2-8 years after the last priming dose. They were distributed according to age at primary immunization into groups: <2 years and 2-13 years and evaluated by years since vaccination (2-3, 4-5 and 6-8). Serum bactericidal antibodies with baby rabbit complement (rSBA) and serogroup C-specific IgG concentrations were measured. The correlate of protection was rSBA titer ⩾8. Subjects with rSBA <8 received a booster dose and antibody levels re-evaluated after 4-6 weeks.

RESULTS

For children primed under 2years of age rSBA titer ⩾8 was demonstrated in 53.3%, 21.7% and 35.0%, 2-3, 4-5, 6-8years, respectively, after vaccination, compared with 70.0%, 45.0% and 53.5%, respectively, for individuals primed at ages 2-13years. rSBA median titers and IgG median levels were higher in the older group. Six to eight years after vaccination the percentage of patients with rSBA titers ⩾8 was significantly higher in the group primed with MCC-TT (78.5%) compared with those primed with MCC-CRM197 [Menjugate® (33.3%) or Meningitec® (35.7%)] (p=0.033). After a booster, 98% achieved rSBA titer ⩾8.

CONCLUSION

Immunity to meningococcal serogroup C in SCD children declines rapidly after vaccination and is dependent on the age at priming. Booster doses are needed to maintain protection in SCD patients. Persistence of antibodies seems to be longer in individuals primed with MCC-TT vaccine comparing to those immunized with MCC-CRM197.

Assessing the Immunogenic Response of a Single Center's Pneumococcal Vaccination Protocol in Sickle Cell Disease

Sickle cell disease (SCD) is the most common inherited hematologic disorder in the United States. Patients with SCD are at increased risk of invasive pneumococcal disease and are reliant on both early penicillin prophylaxis and antipneumococcal vaccination for prevention of infection. Although studies examining vaccine response have demonstrated a drop-off of titer response after 3 years, an optimal vaccination regimen has not been identified. Our study sought to assess the immunogenicity of our center's pneumococcal vaccination strategy, which included Prevnar (PCV-7) (before the introduction of PCV-13) followed by Pneumovax (PPV-23) given routinely at 2 and 5 years of age and then every 5 years thereafter. Our goal was to assess vaccine response in a population of patients with SCD who had received vaccines according to this regimen using multiplex bead analysis. Our study demonstrated a significant percentage of persons with SCD do not maintain a sufficient vaccination response to PPV-23 for 5 years. Our study revealed that only 36% of patients had protective levels of antipneumococcal antibody titers at an average of 37 months after vaccination. Most alarmingly, within the group of patients with subtherapeutic titers, 64% demonstrated vaccine response to <25% of the tested serotypes. These findings were significantly associated with duration of time since last vaccine administration, but the mean age of lack of response was below the 3-year window where vaccine response was previously reported to wane. Our results indicate antipneumococcal immunity may not be optimally maintained using this vaccination strategy in patients with SCD leaving them vulnerable to invasive pneumococcal disease. Many pediatric hematologists stop prophylactic penicillin at 5 years of age making these results alarming. We recommend further investigation into an optimal vaccine schedule and monitoring of antipneumococcal titers in at-risk patients.

Nramp1 and Other Transporters Involved in Metal Withholding during Infection

During the course of infection, many natural defenses are set up along the boundaries of the host-pathogen interface. Key among these is the host response to withhold metals to restrict the growth of invading microbes. This simple act of nutritional warfare, starving the invader of an essential element, is an effective means of limiting infection. The physiology of metal withholding is often referred to as "nutritional immunity," and the mechanisms of metal transport that contribute to this host response are the focus of this review.

Transfusion of stored blood impairs host defenses against Gram-negative pathogens in mice

BACKGROUND

Although human red blood cell (RBC) units may be refrigerator stored for up to 42 days, transfusion of older RBCs acutely delivers a large bolus of iron to mononuclear phagocytes. Similarly, iron dextran circulates in plasma for hours to days and is progressively cleared by mononuclear phagocytes, which return iron to plasma. Finally, malaria infection continuously delivers iron to macrophages by intra- and extravascular hemolysis. Studies suggest that iron administration increases infectious risk.

STUDY DESIGN AND METHODS

To assess the effects of increased iron availability on susceptibility to infection, we infected mice with model Gram-negative intracellular or extracellular pathogens (Salmonella typhimurium or Escherichia coli, respectively), accompanied by RBC transfusion, iron dextran administration, or malarial coinfection.

RESULTS

In our mouse models, transfusion of older RBCs exacerbates infection with both Gram-negative pathogens. Although iron dextran exacerbates E. coli infection to a similar extent as transfusion of corresponding amounts of iron, higher iron doses are required to produce comparable effects with S. typhimurium. Coinfection of mice with Plasmodium yoelii and S. typhimurium produces overwhelming Salmonella sepsis. Finally, treating mice with antibiotics abrogates the enhancing effect on E. coli infection of both older RBC transfusion and iron dextran administration.

CONCLUSIONS

Transfusion of older RBCs exacerbates Gram-negative infection to a similar extent as malaria coinfection or iron dextran administration. Appropriate antibiotic therapy abrogates the effect of older RBC transfusions on infection with E. coli. Iron delivery to macrophages may be an underappreciated mechanism mediating, at least some, adverse effects of RBC transfusions.

TNF-α, IFN-γ, IL-10, and IL-4 levels were elevated in a murine model of human sickle cell anemia maintained on a high protein/calorie diet

Increased frequency and risk of infection is one of the well described complications of sickle cell anemia (SCA). Dietary supplementation in children with SCA and growth retardation improved growth and decreased incidence of infection. We investigated the impact of a high protein diet on weight gain, hematological profile, and immune cytokine levels in the Berkeley model of SCA, 16 of which were randomized to either regular mouse diet with 20% of calories from protein (n = 8) or a test feed with 35% of calories from protein (n = 8). Control mice (C57BL/6, n = 16) were correspondingly randomized, and were all feed ad libitum for three months with actual intake estimated by subtracting the weight of gnaw waste from that of the feed given. Blood was collected at sacrifice by cardiac puncture and plasma levels of T helper cell 1 (TH1) and TH2 associated cytokines were measured using a multiplex antibody immobilized bead assay. SCA mice receiving the 35% protein diet had modest improvements in weight, red blood cell count, and hemoglobin level, with a slight decrease in reticulocyte count compared with SCA mice on the regular mouse diet. Furthermore, they also had significantly higher plasma levels of cytokines tumor necrosis factor (TNF)-α (P = 0.02), interferon (IFN)-γ (P = 0.01), interleukin 10 (IL-10; P = 0.02), and IL-4 (P = 0.02) compared with those that received the 20% protein diet. We conclude that providing additional protein calories to transgenic SCA mice increased the plasma levels of acute inflammatory cytokines associated with immune response to infection, which might partly explain decreased episodes of infection observed among supplemented children with SCA.

Systematic review of current and emerging strategies for reducing morbidity from malaria in sickle cell disease

Sickle cell disease (SCD) is a chronic debilitating disorder affecting erythrocytes, which is especially prevalent throughout Sub-Saharan Africa and among individuals of African descent. Because malaria is thought to be a significant cause of morbidity and mortality in patients with SCD, malaria chemoprophylaxis is often recommended for these patients. In SCD, malaria chemoprophylaxis reduces malaria parasite count, anaemia and the need for blood transfusion, and improves clinical outcomes. However, the effectiveness of malaria chemoprophylaxis in the setting of SCD is based on a few studies conducted prior to the emergence of widespread antimalarial drug resistance. Consequently, it is uncertain what the optimal strategy for managing patients with SCD in malarious areas should be. Despite the widespread use of hydroxyurea in non-malarious regions, little is known about its effect in malaria-endemic areas or on malaria-related outcomes. On the one hand, hydroxyurea upregulates intercellular cell adhesion molecule 1 (ICAM-1), the cell surface receptor for adhesion of Plasmodium falciparum-infected erythrocytes, and theoretically, it could enhance parasite replication. On the other hand, hydroxyurea increases levels of foetal haemoglobin, which is protective against malaria. We explore what is currently known about the interactions between SCD and malaria and review the published literature on the efficacy of malaria chemoprophylaxis in SCD. We also consider alternative strategies, including hydroxyurea, in the reduction of malaria-associated morbidity and mortality in patients with SCD.

Oxidative stress in sickle cell disease; pathophysiology and potential implications for disease management

Sickle cell disease (SCD) is a hemoglobinopathy characterized by hemolytic anemia, increased susceptibility to infections and vaso-occlusion leading to a reduced quality of life and life expectancy. Oxidative stress is an important feature of SCD and plays a significant role in the pathophysiology of hemolysis, vaso-occlusion and ensuing organ damage in sickle cell patients. Reactive oxygen species (ROS) and the (end-)products of their oxidative reactions are potential markers of disease severity and could be targets for antioxidant therapies. This review will summarize the role of ROS in SCD and their potential implication for SCD management.

Septic arthritis of the hip in adults with sickle cell anemia

Although the presence of osteonecrotic bone is known to make joints more prone to infection, acute septic joint in hip osteonecrosis has not frequently been reported in adults with sickle cell disease. The clinical features at the time of admission, imaging findings suggesting the diagnosis, modes of treatment and sequelae of septic arthritis of twenty-four hip joints with osteonecrosis in patients with sickle cell disease were studied retrospectively over a 25-years period. This study evaluated also the complications, the efficiency and the risk of total hip arthroplasty in these patients. Most patients were in the third decade of life. Staphylococcus and Gram negative infection predominated. Treatment was first conservative but most of the patients needed surgery to treat infection and sequelae related to infection. A total hip arthroplasty was performed later in twenty joints. No deaths were observed, but complications occurred. Twenty of the patients in our study underwent delayed total hip arthroplasties following repeated aspirations of the joint and intravenous antibiotics. With an experienced surgical and medical team and multidisciplinary management of these patients undergoing total hip arthroplasty after hip infection, our rate of complications was acceptable.

Septic arthritis in adults with sickle cell disease often is associated with osteomyelitis or osteonecrosis

BACKGROUND

Septic arthritis is a known complication of sickle cell disease (SCD) in children, and the association with osteomyelitis and osteonecrosis has been described. However, it is unclear whether this association applies to adults.

QUESTIONS/PURPOSES

We therefore asked whether septic arthritis is a frequent complication in adults with SCD and whether it also is associated with osteomyelitis or osteonecrosis.

METHODS

We retrospectively reviewed the charts of 2000 consecutive adult patients diagnosed with SCD and recorded symptoms, select findings during physical examination, laboratory data, and select radiographic CT, and MRI observations.

RESULTS

Fifty-nine of the 2000 patients (3%) had septic arthritis, 56 of the 59 patients had hemoglobin SS. Thirty-six of the 59 infections (61%) were in the hip. The most frequent findings were pain, swelling, fever greater than 38.2 degrees C (71% of cases), a leukocyte count exceeding 15,000/mm(3) (range, 7900-32,300/mm(3)), a Westergren sedimentation rate greater than 24 mm/hour, and C-reactive protein exceeding 20 mg/L. Cultures were positive in 96% of the joint aspirates. Staphylococcus and Gram-negative infection predominated; no patients had Salmonella joint infections. Preexisting factors of bacterial arthritis included osteonecrosis (29 patients) and osteomyelitis (37 cases) in childhood. Diabetes, rheumatoid arthritis, glucocorticoids, and immunoparesis related to medical treatment by hydroxyurea were associated comorbidities. CT and MRI confirmed the diagnosis of associated osteonecrosis or osteomyelitis and allowed joint aspiration and detection of soft tissue abscess.

CONCLUSIONS

The incidence of septic arthritis in adults with SCD is low, but often is associated with osteomyelitis or osteonecrosis.

LEVEL OF EVIDENCE

Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Association of the +874 T/A interferon gamma polymorphism with infections in sickle cell disease

Infectious complications are a leading cause of morbidity and mortality in patients with sickle cell disease. Several mechanisms are supposed to contribute to this susceptibility. The exact reasons for the susceptibility of sickle cell patients to infection are not clear and are still a matter of debate. Interferon gamma (IFNgamma) is a key cytokine involved mainly in the defence against intracellular pathogens. We investigated a possible association of an IFNgamma +874 T/A polymorphism and infectious complications in sickle cell patients. Seventy-two sickle cell patients were typed for +874 T/A IFNgamma polymorphism. Genotype frequencies were different between cases and controls. Indeed, the T allele frequency was significantly higher in patients with infections than in patients without infections (P = 0.014). Our results suggest that the +874 T/A IFNgamma polymorphism is associated with infectious complications in sickle cell patients. T allele could be involved in infections in sickle cell patients.

WHO guidelines for antimicrobial treatment in children admitted to hospital in an area of intense Plasmodium falciparum transmission: prospective study

OBJECTIVES

To assess the performance of WHO's "Guidelines for care at the first-referral level in developing countries" in an area of intense malaria transmission and identify bacterial infections in children with and without malaria.

DESIGN

Prospective study.

SETTING

District hospital in Muheza, northeast Tanzania.

PARTICIPANTS

Children aged 2 months to 13 years admitted to hospital for febrile illness.

MAIN OUTCOME MEASURES

Sensitivity and specificity of WHO guidelines in diagnosing invasive bacterial disease; susceptibility of isolated organisms to recommended antimicrobials.

RESULTS

Over one year, 3639 children were enrolled and 184 (5.1%) died; 2195 (60.3%) were blood slide positive for Plasmodium falciparum, 341 (9.4%) had invasive bacterial disease, and 142 (3.9%) were seropositive for HIV. The prevalence of invasive bacterial disease was lower in slide positive children (100/2195, 4.6%) than in slide negative children (241/1444, 16.7%). Non-typhi Salmonella was the most frequently isolated organism (52/100 (52%) of organisms in slide positive children and 108/241 (45%) in slide negative children). Mortality among children with invasive bacterial disease was significantly higher (58/341, 17%) than in children without invasive bacterial disease (126/3298, 3.8%) (P<0.001), and this was true regardless of the presence of P falciparum parasitaemia. The sensitivity and specificity of WHO criteria in identifying invasive bacterial disease in slide positive children were 60.0% (95% confidence interval 58.0% to 62.1%) and 53.5% (51.4% to 55.6%), compared with 70.5% (68.2% to 72.9%) and 48.1% (45.6% to 50.7%) in slide negative children. In children with WHO criteria for invasive bacterial disease, only 99/211(47%) of isolated organisms were susceptible to the first recommended antimicrobial agent.

CONCLUSIONS

In an area exposed to high transmission of malaria, current WHO guidelines failed to identify almost a third of children with invasive bacterial disease, and more than half of the organisms isolated were not susceptible to currently recommended antimicrobials. Improved diagnosis and treatment of invasive bacterial disease are needed to reduce childhood mortality.

Both hemolytic anemia and malaria parasite-specific factors increase susceptibility to Nontyphoidal Salmonella enterica serovar typhimurium infection in mice

Severe pediatric malaria is an important risk factor for developing disseminated infections with nontyphoidal Salmonella serotypes (NTS). While recent animal studies on this subject are lacking, early work suggests that an increased risk for developing systemic NTS infection during malaria is caused by hemolytic anemia, which leads to reduced macrophage microbicidal activity. Here we established a model for oral Salmonella enterica serotype Typhimurium challenge in mice infected with Plasmodium yoelii nigeriensis. Initial characterization of this model showed that 5 days after coinoculation, P. yoelii nigeriensis infection increased the recovery of S. Typhimurium from liver and spleen by approximately 1,000-fold. The increased bacterial burden could be only partially recapitulated by antibody-mediated hemolysis, which increased the recovery of S. Typhimurium from liver and spleen by 10-fold. These data suggested that both hemolysis and P. yoelii nigeriensis-specific factors contributed to the increased susceptibility to S. Typhimurium. The mechanism by which hemolysis impaired resistance to S. Typhimurium was further investigated. In vitro, S. Typhimurium was recovered 24 h after infection of hemophagocytic macrophages in 2-fold-higher numbers than after infection of mock-treated macrophages, making it unlikely that reduced macrophage microbicidal activity was solely responsible for hemolysis-induced immunosuppression during malaria. Infection with P. yoelii nigeriensis, but not antibody-mediated hemolysis, reduced serum levels of interleukin-12p70 (IL-12p70) in response to S. Typhimurium challenge. Collectively, studies establishing a mouse model for this coinfection suggest that multiple distinct malaria-induced immune defects contribute to increased susceptibility to S. Typhimurium.

Infection in sickle cell disease: a review

Infection is a significant contributor to morbidity and mortality in sickle cell disease (SCD). The sickle gene confers an increased susceptibility to infection, especially to certain bacterial pathogens, and at the same time infection provokes a cascade of SCD-specific pathophysiological changes. Historically, infection is a major cause of mortality in SCD, particularly in children, and it was implicated in 20-50% of deaths in prospective cohort studies over the last 20 years. Worldwide, it remains the leading cause of death, particularly in less developed nations. In developed countries, measures to prevent and effectively treat infection have made a substantial contribution to improvements in survival and quality of life, and are continually being developed and extended. However, progress continues to lag in less developed countries where the patterns of morbidity and mortality are less well defined and implementation of preventive care is poor. This review provides an overview of how SCD increases susceptibility to infections, the underlying mechanisms for susceptibility to specific pathogens, and how infection modifies the outcome of SCD. It also highlights the challenges in reducing the global burden of mortality in SCD.

The spleen in the sickling disorders: an update

In early life, patients with sickle cell disease (SCD) can have acute, life-threatening emergencies related to splenic hypofunction (overwhelming bacterial sepsis), as well as anemic crises from acute splenic sequestration because of sudden pooling of blood in the spleen. The landmark penicillin prophylaxis study in 1985 showed a remarkable decrease in mortality from sepsis in young children with SCD who were treated with oral penicillin prophylaxis compared to placebo. Since that study, newborns are screened for SCD and placed on oral penicillin prophylaxis in nearly all of the United States, as well as in other countries where the disease is highly prevalent. The previously described permanent, complete and nearly universal "autosplenectomy" emerging by late childhood or early adulthood is now challenged by recent findings of reversibility of splenic dysfunction by the antisickling drug hydroxyurea or by successful allogeneic stem cell transplantation, even in older patients. Imaging techniques for hypofunction of the spleen are the most commonly used modalities to guide the clinician in decisions regarding medical or surgical management.

Focal Salmonella enteritidis infection in a patient with HIV infection and other multiple causes of immunodeficiency

An HIV-infected man receiving antiretroviral therapy-who also had lupus-like vasculitis and membranous glomerulonephritis (treated with prednisolone and azathioprine), beta-thalassaemia minor trait and post-radiotherapy functional asplenia (mimicking sickle cell disease-induced hyposplenism)-developed focal soft issue and bone infection caused by Salmonella enteritidis at the site of previous mycobacterial infection.

Tuberculosis in adult patients with sickle cell disease

OBJECTIVE

Although infection, in particular pulmonary infection, is a common complication of sickle cell disease (SCD) and although SCD is frequent in populations where the prevalence of tuberculosis is high, the relationship between the two diseases has never been studied. We conducted a study to assess the epidemiological and clinical pattern of tuberculosis in adult patients with SCD.

METHODS

We retrospectively reviewed the cases of tuberculosis reported within our cohort of 457 SCD patients from January 1998 to April 2006 in the adult sickle cell center of Hôpital Tenon, Paris, France.

RESULTS

We identified 12 cases of tuberculosis, 8 men and 4 women. There were 7 lymph node lesions, 3 pulmonary lesions and 2 vertebral lesions. The incidence of pulmonary and extrapulmonary tuberculosis was respectively of 82 and 246 cases per 100,000, to compare with an expected incidence of 184 cases, and 65 cases per 100,000. Three of the patients with lymph node tuberculosis were asymptomatic. No case of multi-organ involvement was seen. No other cause of immunodepression than the functional asplenia was found. All the patients showed clinical improvement under treatment.

CONCLUSIONS

In SCD patients, lymph node tuberculosis appears to have a higher incidence than that in an epidemiologically comparable population, and has a rather indolent presentation and a favourable outcome. Pulmonary tuberculosis seems to be less frequent than expected.

Bloodstream infections in hospitalized adults with sickle cell disease: a retrospective analysis

Bloodstream infections (BSI) are a common cause of morbidity and mortality in people with sickle cell disease (SCD). In children with SCD, BSI are most often caused by encapsulated organisms. There is a surprising paucity of medical literature that is focused on evaluating SCD adults with BSI. We reviewed the charts of adults with SCD and BSI who were admitted to our hospital between April 1999 and August 2003. During this period a total of 1,692 hospital admissions for 193 adults with SCD were identified and 28% of these patients had at least 1 episode of positive blood cultures, with 69 episodes (17%) considered true BSI. Nosocomial BSI occurred in 34 episodes (49%). Among community BSI, in contrast to BSI in children with SCD, Streptococcus pneumoniae was rarely encountered. A high incidence of staphylococcal BSI in adults with SCD was noted. Twenty-eight percent of all BSI were caused by Staphylococcus aureus, and 15 of 22 isolates (68%) of these were methicillin-resistant. Gram-negative organisms, anaerobes, and yeast were found in 21 (27%), 3 (4%), and 4 isolates (5%) of BSI, respectively. Since over 80% of BSI were considered catheter-related, the higher incidence of gram-positive bacterial infections was likely due to the presence of indwelling central venous catheters. Empiric therapy for adults with SCD suspected of having BSI, especially in the presence of indwelling central venous catheters, should include antimicrobial therapy targeted at gram-positive bacteria (especially MRSA) and gram-negative bacteria. Also, if patients are critically ill, consideration should be made to include antifungal agents. Additional research into the adult SCD population appears necessary to further define this problem.

Ceftriaxone-resistant Salmonella septicemia and osteomyelitis in sickle cell disease adults

The majority of data evaluating Salmonella infections in sickle cell anemia (SCD) comes from studies performed in children. We report a SCD adult who presented with ceftriaxone-resistant Salmonella bacteremia. After appropriate initial therapy, persistent back pain prompted evaluation by magnetic resonance imaging of the spine, which revealed osteomyelitis and a psoas abscess. The patient responded to percutaneous drainage and antibiotics. This report summarizes some of the findings of large SCD studies evaluating Salmonella bacteremia and osteomyelitis, focusing on adults. Our case exemplifies the need for antibiotic coverage for Salmonella species in adult SCD patients with septicemia. We argue that imaging studies looking for osteomyelitis should be done routinely in SCD patients with Salmonella bacteremia.

The iron efflux protein ferroportin regulates the intracellular growth of Salmonella enterica

We investigated the influence of the macrophage iron exporter ferroportin and its ligand hepcidin on intracellular Salmonella growth. Elevated ferroportin expression inhibited bacterial multiplication; hepcidin-induced ferroportin down-regulation enhanced it. Expression analysis of iron-responsive Salmonella genes indicated ferroportin-mediated iron deprivation. These results demonstrate a role for ferroportin in antimicrobial resistance.

Important bacterial gastrointestinal pathogens in children: a pathogenesis perspective

This article focuses on the five most common bacterial enteropathogens of the developed world--Helicobacter pylori, Escherichia coli, Shigella, Salmonella, and Campylobacter--from the perspective of how they cause disease and how they relate to each other. Basic and recurring themes of bacterial pathogenesis, including mechanisms of entry, methods of adherence, sites of cellular injury, role of toxins, and how pathogens acquire particular virulence traits (and antimicrobial resistance), are discussed.

Sickle cell disease in central India

OBJECTIVE

The incidence and the risk factors of sickle cell disease (SCD), vaccinated with Pneumococcal vaccine and on penicillin prophylaxis has not been previously reported in India.

METHODS

This prospective hospital based study followed 325 children on penicillin prophylaxis, of which 161 were vaccinated for pneumococci, over 146.84 person years to determine the incidence and determinants of crisis (SCC) and infections. The average age at presentation was 7.05 +/- 3.26 years with male preponderance below 2 years.

RESULTS

The main causes for hospitalizations were for blood transfusion, SCC and infections. The incidence of SCC was 1.25 per patient per year and that of infection was 1.38 per person per year. The risk factors for SCC were Mahar caste (p = 0.007) non-compliance (p = 0.000) and protein energy malnutrition (PEM) (p = 0.0015) and for infection were also PEM (p = 0.023), Mahar caste (p = 0.021) and noncompliance (p = 0.001).

CONCLUSION

Malnutrition and non-compliance with medication increased the patient's susceptibility to SCC and infections.

Retrospective review of osteoarticular infections in a pediatric sickle cell age group

Patients with sickle cell disease have been documented to be particularly susceptible to osteoarticular infections. Controversy exists concerning the bacteriology, etiology, and clinical presentation in differentiating osteoarticular infections from bone infarct. We retrospectively reviewed all cases from our institution over the past 22 years of osteoarticular infections in children who carry the diagnosis of sickle cell disease. Two thousand consecutive patient charts of children enrolled in the Pediatric Sickle Cell Clinic of our institution between 1973 and 1995 were evaluated. There were 14 cases of bone or joint infections (10 osteomyelitis, four septic arthritis). There was one case of multicentric osteomyelitis and one case of meningitis complicating the septic arthritis. There were nine male and five female patients with ages ranging from 6 months to 17 years (mean, 8.0). All patients were noted to have hemoglobin SS. The predominant presenting symptoms were pain (79% of cases) and swelling (71% of cases). The most frequent physical findings were fever >38.2 degrees C (71% of cases) and tenderness (86% of cases). Ninety-three percent of the children had a white blood count exceeding 15,000/mm3 (range, 7,900-32,300). Westergren sedimentation rates ranged from 14 to 89 mm/h with 93% of the children exceeding the normal value in our hospital. Cultures were positive in 75% of tissue biopsies, 58% of the blood cultures, and 70% of the bone or joint aspirates. The most common offending organism found in osteomyelitis was Salmonella (eight of 10 cases); however, no predominant organism found was identified in cases of septic arthritis. Radiographs and bone scans were of limited value in the differential diagnosis between osteoarticular infections and bone infarction. Early diagnosis and treatment of osteoarticular infections is key to satisfactory outcome. This study suggests that an ill-appearing patient with a fever >38.2 degrees C, pain, and swelling should prompt the physician to aspirate or biopsy the area and not rely on diagnostic studies that we found to be unreliable.