Depletion of Intestinal Microbiome Partially Rescues Bone Loss in Sickle Cell Disease Male Mice.

Osteoporosis or osteopenia are common clinical manifestations of sickle cell disease (SCD) with unclear mechanisms. Since senescence of circulating neutrophil can be modulated by signals derived from intestinal microbiome and neutrophils are abundant in bone marrow and can regulate osteoblasts and osteoclasts, we examined whether gut microbiome contributes to bone loss in SCD mice. SCD and their littermates control mice were treated with antibiotics to deplete gut microbiome. At the end of 7 weeks treatment, serum was collected for biochemistry marker measurements. Bone mass and remodeling were evaluated by dual beam X-ray absorptiometry, micro-computed tomography, and histomorphometry. Bone-related genes in tibia and barrier marker genes in the small intestine were analyzed by quantitative PCR. Antibiotic treatment rescued increased intestinal inflammatory cytokine marker genes (Tnfα, IL17, Ifnγ) expression, rescued decreased intestinal barrier marker genes (claudin 3 and claudin 15) expression, and rescued increased serum cytokines (IFNγ, IL27, IL10) in SCD mice. Antibiotic significantly improved decreased bone mass in SCD mice mainly through enhanced osteoblast function and increased osteoblast-related genes (Runx2 and Igf1) expression in SCD mice. Our findings support that increased bacteria load augments antigenic load traversing the impaired intestinal barrier through inflammation, leading to increased inflammatory cytokines, impaired osteoblast function, and bone loss in SCD mice.

Pantoea Species Bacteremia in a Child With Sickle Cell Disease: Looking for a Culprit.

Pantoea agglomerans has been classically associated with cellulitis or synovitis secondary to penetrating trauma by vegetation. It is an infrequent cause of systemic infections. We describe the case of a 5-year-old girl with sickle cell disease with P. agglomerans bacteremia and review its potential causes.

Predictors of bacteremia among children with sickle cell disease presenting with fever.

INTRODUCTION: Bacterial sepsis is more common and potentially life threatening in children with sickle cell disease (SCD). Identification of variables that predict bacteremia may aid clinicians in recognizing patients with SCD at higher risk for sepsis. OBJECTIVE: To determine whether absolute neutrophil count (ANC) >20×10/L is an independent risk factor for bacteremia in children with SCD and to identify other predictors of bacteremia in this population. METHODS: A case-control study was conducted. Subjects were 0 to 18 years of age admitted to a tertiary care pediatric hospital over a 17-year period with SCD and fever at presentation. Cases had bacteremia, whereas controls had negative blood cultures. RESULTS: Data were analyzed for 40 cases and 120 controls. ANC>20×10/L was significantly more prevalent among cases (odds ratio [OR], 7.0; 95% confidence interval [CI], 2.6-18.9). Cases were more likely to have emesis (OR, 2.9; 95% CI, 1.0-8.4) and a higher proportion of band cells (OR, 1.3; 95% CI, 1.1-1.4) at presentation. CONCLUSIONS: In a febrile child with SCD, an ANC>20×10/L, a higher proportion of band cells, and the presence of vomiting were associated with an increased likelihood of bacteremia.

Prevalence of pneumococcal bacteremia in children with sickle cell disease.

We performed a retrospective chart review of children with sickle cell disease hospitalized for fever at our local institution. We reviewed 456 hospitalizations in 133 patients between January 2006 and June 2012. The prevalence of true bacteremia was 4%. The mean C-reactive protein values and temperatures were nonsignificantly higher in patients with positive blood cultures. The mean time to detection was 22.5 hours in bacteremia compared to 32.6 hours in blood cultures that grew contaminants (p = .034). Only two (0.4%) cases of pneumococcal bacteremia were reported and both occurred before May 2010, which marks the introduction of 13-valent pneumococcal vaccine (PCV13). Both patients with pneumococcal bacteremia had discontinued penicillin prophylaxis after the age of 5 years. The first patient was immunized but contracted a nonvaccine serotype (23B). The second patient was partially vaccinated and acquired a vaccine-preventable serotype (23F). Both serotypes were sensitive to ceftriaxone and vancomycin; one was resistant to penicillin. This is the first study reporting the prevalence of pneumococcal bacteremia since the introduction of PCV13.

Hospitalization for invasive pneumococcal disease in a national sample of children with sickle cell disease before and after PCV7 licensure.

OBJECTIVE: To estimate national hospitalization rates for invasive pneumococcal disease (IPD) in children with sickle cell disease (SCD) before and after the 2000 licensure of the heptavalent pneumococcal conjugate vaccine (PCV7). PROCEDURE: We performed a retrospective trend analysis of the 1994-2007 Nationwide Inpatient Sample databases. Hospitalizations involving children with SCD and IPD were identified by ICD-9CM code. The primary outcomes, the annual hospitalization rate for IPD in children with SCD and the proportion of hospitalizations for IPD per 100 total SCD hospitalizations, were analyzed using multivariable linear regression and contingency analysis, respectively. RESULTS: A total of 1,242 hospitalizations for IPD in SCD patients were identified from 1994-2007, with a mortality rate of 2.4%. The national mean annual rate of IPD hospitalization decreased by 65%, from 131.8 cases/year from 1994 to 2000 to 45.5 cases/year from 2001 to 2007 (P = 0.001). The national proportion of hospitalizations for IPD per 100 total SCD hospitalizations decreased from 0.4 to 0.15 (P < 0.0001) over the same interval. Following PCV7 licensure, the mean annual cumulative hospital days and cumulative hospital charges decreased nationally by 53% and 36%, respectively. CONCLUSION: In a national sample, PCV7 licensure is temporally associated with a nearly threefold reduction in IPD hospitalizations in children with SCD.

Osteomyelitis and pyomyositis due to Pseudomonas aeruginosa in a child with sickle ß°-thalassemia.

Sickle cell osteomyelitis is usually due to Salmonella or Staphylococcal etiology. Pseudomonas as a cause of sickle cell osteomyelitis is rare. Similarly, pyomyositis is a rare complication in children with sickle cell disease and few cases have been reported, predominantly due to Staphylococcus. We describe an 8-year-old boy who presented with high-grade fever and tender, swollen left thigh. There was a history of intramuscular injections in the left thigh. He also had severe anemia, hepatosplenomegaly, and laboratory evidence of hemolysis. Hemoglobin electrophoresis showed sickle ß-thalassemia. Magnetic resonance imaging of the left thigh showed evidence of osteomyelitis with pyomyositis. Surgical drainage of the pus was done and Pseudomonas aeruginosa was isolated. He was treated with intravenous antibiotics for 8 weeks. The child had a protracted course of illness with development of pathologic fracture of the femur. Clinicians need to be aware of Pseudomonas infection as a complication in children with sickle cell disease, as this affects therapeutic decisions, including the choice of antibiotics.

Susceptibility to invasive bacterial infections in children with sickle cell disease.

Individuals with sickle cell disease (SCD) demonstrate an increased susceptibility to invasive bacterial infections (IBI). The most common organisms causing IBI are Streptococcus pneumoniae, nontyphi Salmonella species and Haemophilus influenzae type b (Hib). IBI are the most common causes of death in children below 5 years of age with SCD. Increased susceptibility to IBI is because of several factors including dysfunctional antibody production and opsonophagocytosis as well as defective splenic clearance. Early diagnosis of Hib and pneumococcal infections combined with antibiotic prophylaxis and immunization programs, could lead to significant improvements in mortality, especially in Africa.

Bordetella holmesii bacteremia in sickle cell disease.

Patients with sickle cell disease (SCD) have an increased risk of invasive bacterial infection because of hyposplenism. Bordetella holmesii is a recently described Gram-negative coccobacillus with an apparent predilection for asplenic hosts. We report two patients with SCD and B. holmesii bacteremia. Fastidious growth in culture and a typically uncomplicated clinical course distinguish B. holmesii infection from other invasive bacterial infections in SCD. Providers for patients with SCD should be aware of this pathogen and ensure that their microbiology laboratories are capable of isolating and identifying this organism.

Bacteroides (Parabacteroides) distasonis splenic abscess in a sickle cell patient.

Splenic abscess is not an uncommon complication of patients with sickle-cell disease. Here we describe an 18 year-old boy with sickle cell disease and left upper quadrant abdominal pain. Computerized axial tomography revealed left sided free flowing pleural effusion and splenomegaly with liquefaction and possible gas formation. The splenic fluid grew an unusual organism known as Bacteroides distasonis. The patient received antimicrobial therapy and underwent a splenectomy with full recovery. The spleen was cystically infarcted and measured 22 x 16 x 5 cm. The capsule was thickened and covered by fibrinous exudate. Histopathologic examination of the spleen showed complete necrosis with reparative fibrosis. This case presents an unusual cause of splenic abscess due to Bacteroides distasonis with a subacute to chronic course. The presence of fever and left sided pleuritic chest pain in patients with sickle cell disease should raise the suspicion of splenic abscess.

Positive blood cultures in sickle cell disease: time to positivity and clinical outcome.

PURPOSE: To prospectively identify all cases of bacteremia in children with sickle cell disease (SCD), establish time to positivity for various microorganisms, correlate clinical findings with microbiology data, and determine the antibiotic resistance pattern of the pneumococcal isolates. METHODS: All positive blood cultures from children with SCD followed at the Children's Hospital of Philadelphia from January 1993 through May 2001 were included. Isolates were classified as pathogen or contaminant. Demographic and clinical information was abstracted from the medical records. Time to positivity and antibiotic resistance data were generated in the microbiology laboratory. RESULTS: One hundred forty-one positive blood culture bottles were obtained during distinct febrile episodes. Thirty-nine percent contained pathogens and 61% contained contaminants. The average time to positivity was 17.1 hours in the pathogen group and 29.5 hours in the contaminant group (P < 0.0001). Streptococcus pneumoniae was the most common pathogen (42% of total), with a mean patient age of 3.5 years. Gram-negative rods were the second most common organism (28% of total), with a mean patient age of 8.1 years. Thirty-one percent of the pneumococcal isolates were resistant to penicillin. Thirty-five percent of the pneumococcal isolates grew from children with a focus of infection. Acute chest syndrome was noted in 26% of patients with a positive blood culture for S. pneumoniae. Sixty-seven percent of Salmonella isolates and 50% of Staphylococcus aureus isolates grew from patients who developed osteomyelitis. CONCLUSIONS: The average time to positivity for pathogens can be used in conjunction with other factors to determine the length of observation required for children with SCD who present with febrile illness. Chest radiographs should be obtained on children with SCD who are bacteremic with S. pneumoniae. Bone scans should be obtained on children with SCD who are bacteremic with Salmonella or S. aureus.

Predictors of bacteremia in febrile children with sickle cell disease.

PURPOSE: Bacteremia is an important cause of death and complications in children with sickle cell disease (SCD), yet predictors of bacteremia in these patients have not been well identified. The purpose of this study was to test whether clinical and hematologic variables commonly used to predict bacteremia in normal young children with fever could accurately predict bacteremia in febrile children with SCD. PATIENTS AND METHODS: The authors reviewed the medical records of all patients with SCD younger than 18 years of age over a 10-year period at a single institution for febrile events. They tested the univariate associations of age, height of fever, white blood cell count (WBC), absolute neutrophil count (ANC), and absolute band count (ABC) with bacteremia. Three separate multivariate analyses were performed using the predictor variables age, temperature, and one of three hematologic variables (ANC, WBC, or ABC) with the outcome bacteremia. RESULTS: There were 175 evaluable febrile events, of which 8 (4.6%) were associated with bacteremia. In the multivariate analyses, all hematologic variables, but not age or height of fever, retained significant associations with bacteremia. CONCLUSIONS: In febrile children with SCD, WBC, ANC, and ABC are all independently associated with bacteremia when adjusting for height of fever and age. Hematologic variables may be useful in developing prediction algorithms to identify febrile patients with SCD at higher risk of bacteremia. These data emphasize the need for a national trial to develop a predictive model with defined thresholds.

Influence of penicillin prophylaxis on antimicrobial resistance in nasopharyngeal S. pneumoniae among children with sickle cell anemia. The Ancillary Nasopharyngeal Culture Study of Prophylactic Penicillin Study II.

PURPOSE: To evaluate the consequences of prolonged prophylactic penicillin use on the rates of nasopharyngeal colonization with Streptococcus pneumoniae and the prevalence of resistant pneumococcal strains in children with sickle cell anemia. METHODS: Nasopharyngeal specimens were obtained from children with sickle cell anemia (Hb SS or Hb S beta degrees thalassemia) at 10 teaching hospitals throughout the United States. These patients were participating in a prospective, randomized, placebo-controlled trial in which they were prescribed prophylactic penicillin before their fifth birthday and were randomized to prophylactic penicillin or placebo after their fifth birthday (PROPS II). The specimens were cultured for S. pneumoniae, and isolates were analyzed for antimicrobial susceptibility to nine commonly prescribed antimicrobial agents. RESULTS: Of the 226 patients observed, an average of 8.4 specimens were collected per patient. From 1,896 individual culture specimens, 5.5% of the specimens were positive for S. pneumoniae; 27% of patients had at least one positive culture. Nine percent of the study patients had at least one isolate of penicillin intermediate or resistant pneumococci. There was no significant difference in the percent of positive cultures for S. pneumoniae in those patients given penicillin prophylaxis after 5 years of age (4.1%) compared with those patients given placebo after 5 years of age (6.4%). Likewise, there was no significant difference (p = 0.298) in the percent of patients with at least one positive culture for S. pneumoniae in the group given prophylactic penicillin after 5 years of age (21.8%) compared with the group given placebo after 5 years of age (28.3%). There was no difference between the penicillin and placebo groups in the proportion of patients with penicillin intermediate or resistant pneumococci, but there was a trend toward increased carriage of multiply drug-resistant pneumococci in children > 5 years of age receiving prophylactic penicillin compared to children > 5 years of age receiving placebo. The increased colonization rate with multiply drug-resistant organisms of children > 5 years of age receiving penicillin prophylaxis is not statistically significant. CONCLUSIONS: The potential for continued penicillin prophylaxis to contribute to the development of multiply resistant pneumococci should be considered before continuing penicillin prophylaxis in children with sickle cell anemia who are older than 5 years of age. Added to the published data from PROPS II, which demonstrated no apparent advantage to continue prophylaxis, the data support the conclusion that, for children with no history of invasive pneumococcal disease, consideration should be given to discontinue prophylactic penicillin after their fifth birthday.

Penicillin resistant streptococcus pneumoniae in a Jamaican patient with homozygous sickle cell disease

Penicillin prophylaxis against infection by Streptococcus pneumoniae is now routine in young children with homozygous sickle-cell (SS) disease and the emergence of penicillin-resistant strains is a serious clinical concern. The first death associated with such resistance in a Jamaican child with SS disease is reported

Antibiotic-resistant pneumococcal infection in children with sickle cell disease in the United States.

OBJECTIVE: The purpose of this report is to examine the increasing problem of antibiotic-resistant pneumococcal infection in children with sickle cell disease in the United States. PATIENTS AND METHODS: In this retrospective review, 16 children with sickle cell disease and penicillin-resistant pneumococcal invasive infection were identified. They had a median age of 2 years (range 1-15) and were treated in Memphis, Dallas, Los Angeles, and five other cities between 1987 and early 1995. RESULTS: At presentation, patients frequently had high fever (> or 40.0 degrees C in 75%) and a toxic appearance (44%). Meningitis was present initially in two and diagnosed on days 4 and 5 in two. All were treated with an intravenous cephalosporin and nine received vancomycin. The clinical course was variable: two died within 36 h of presentation. In 20-86% of cases the organisms were resistant to cephalosporins, chloramphenicol, trimethoprim/sulfamethoxazole, erythromycin, and clindamycin; none were resistant to vancomycin. CONCLUSIONS: (a) The increasing prevalence of antibiotic-resistant Streptococcus pneumoniae infection in the United States poses special problems for patients with sickle cell disease. (b) Prompt antibiotic susceptibility testing of pneumococcal isolates should be performed. (c) Initial antibiotic management for patients suspected of sepsis/meningitis should include intravenous cephalosporin and vancomycin. (d) No alternative to penicillin prophylaxis is currently available. (e) An effective conjugated pneumococcal vaccine is needed.

The significance of recurrent tonsillitis in sickle cell disease.

Forty-five patients with homozygous sickle cell disease who had tonsillectomy for recurrent tonsillitis, when compared with 45 matched controls with haemoglobin genotype AA, showed significant differences in the clinical manifestations and complications of recurrent tonsillitis between the two groups. Although throat swabs in the sickle cell group were mostly negative because they were on prophylactic penicillin, all tonsils harboured Streptococcus pneumoniae when cultured. This study suggests the tonsils to be the more specific source of pneumococcal infection that causes systemic complications which increase morbidity and mortality in sickle cell disease. Although the sickle cell patients may be less clinically symptomatic with tonsillitis, the incidence of serious complications caused by pneumococcal infections, now shown to arise from the tonsils, is significant. Adenotonsillar hypertrophy is linked with an increased risk of a sleep apnoea which causes serious neurological complications such as cerebral infarction and stroke. Tonsillectomy has greatly reduced the incidence of complications from pneumococcal infections in the sickle cell group and should therefore be recommended for sickle cell patients taking prophylactic penicillin and still developing pneumococcal infections.

Prevalence of human parvovirus B19 in sickle cell disease and healthy controls.

The serological HPV status of 35 patients with SCA (Hb SS), randomly chosen from a sickle cell clinic in rural south-west Togo and of 13 household members with normal haemoglobin type (Hb AA) was assessed. No difference in HPV-IgG seropositivity rate was found. In 30 urban hospital patients from Abidjan, Ivory Coast, who were in acute painful sickle cell crisis HPV-IgG seropositivity rate increased with age. In only one (HIV positive) patient HPV-IgM antibodies were detected. It is concluded that HPV-infection exists in West Africa (1) and that there is no evidence for increased seroprevalence in SCA (2). HPV does not seem to trigger acute painful crises in SCA (3). The age-specific HPV seropositivity increase in urban patients may be due to differing transmission rates in urban and rural areas.

Identification of the major structural and nonstructural proteins encoded by human parvovirus B19 and mapping of their genes by procaryotic expression of isolated genomic fragments.

Plasma from a child with homozygous sickle-cell disease, sampled during the early phase of an aplastic crisis, contained human parvovirus B19 virions. Plasma taken 10 days later (during the convalescent phase) contained both immunoglobulin M and immunoglobulin G antibodies directed against two viral polypeptides with apparent molecular weights of 83,000 and 58,000 which were present exclusively in the particulate fraction of the plasma taken during the acute phase. These two protein species comigrated at 110S on neutral sucrose velocity gradients with the B19 viral DNA and thus appear to constitute the viral capsid polypeptides. The B19 genome was molecularly cloned into a bacterial plasmid vector. Restriction endonuclease fragments of this cloned B19 genome were treated with BAL 31 and shotgun cloned into the open reading frame expression vector pJS413. Two expression constructs containing B19 sequences from different halves of the viral genome were obtained, which directed the synthesis, in bacteria, of segments of virally encoded protein. These polypeptide fragments were then purified and used to immunize rabbits. Antibodies against a protein sequence specified between nucleotides 2897 and 3749 recognized both the 83- and 58-kilodalton capsid polypeptides in aplastic plasma taken during the acute phase and detected similar proteins in the tissues of a stillborn fetus which had been infected transplacentally with B19. Antibodies against a protein sequence encoded in the other half of the B19 genome (nucleotides 1072 through 2044) did not react specifically with any protein in plasma taken during the acute phase but recognized three nonstructural polypeptides of 71, 63, and 52 kilodaltons present in the liver and, at lower levels, in some other tissues of the transplacentally infected fetus.

Nucleotide sequence and genome organization of human parvovirus B19 isolated from the serum of a child during aplastic crisis.

The nucleotide sequence of an almost-full-length clone of human parvovirus B19 was determined. Whereas the extreme left and right ends of this genomic clone are incomplete, the sequence clearly indicates that the two ends of viral DNA are related by inverted terminal repeats similar to those of the Dependovirus genus. The coding regions are complete in the cloned DNA, and the two large open reading frames which span almost the entire genome are restricted to one strand, as has been found for all other parvoviruses characterized to date. From the DNA sequence we conclude that the organization of the B19 transcription units is similar although not identical to those of other parvoviruses. In particular, we predict that the B19 genome may utilize a fourth promoter to transcribe mRNA encoding the major structural polypeptide, VP2. Analysis of the putative polypeptides confirms that B19 is only distantly related to the other parvoviruses but reveals that there is a small region in the gene probably encoding the major nonstructural protein of B19, which is closely conserved between all of the parvovirus genomes for which sequence information is currently available.