The gut microbiome in sickle cell disease: Characterization and potential implications

BACKGROUND

Sickle Cell Disease (SCD) is an inherited blood disorder that leads to hemolytic anemia, pain, organ damage and early mortality. It is characterized by polymerized deoxygenated hemoglobin, rigid sickle red blood cells and vaso-occlusive crises (VOC). Recurrent hypoxia-reperfusion injury in the gut of SCD patients could increase tissue injury, permeability, and bacterial translocation. In this context, the gut microbiome, a major player in health and disease, might have significant impact. This study sought to characterize the gut microbiome in SCD.

METHODS

Stool and saliva samples were collected from healthy controls (n = 14) and SCD subjects (n = 14). Stool samples were also collected from humanized SCD murine models including Berk, Townes and corresponding control mice. Amplified 16S rDNA was used for bacterial composition analysis using Next Generation Sequencing (NGS). Pairwise group analyses established differential bacterial groups at many taxonomy levels. Bacterial group abundance and differentials were established using DeSeq software.

RESULTS

A major dysbiosis was observed in SCD patients. The Firmicutes/Bacteroidetes ratio was lower in these patients. The following bacterial families were more abundant in SCD patients: Acetobacteraceae, Acidaminococcaceae, Candidatus Saccharibacteria, Peptostreptococcaceae, Bifidobacteriaceae, Veillonellaceae, Actinomycetaceae, Clostridiales, Bacteroidacbactereae and Fusobacteriaceae. This dysbiosis translated into 420 different operational taxonomic units (OTUs). Townes SCD mice also displayed gut microbiome dysbiosis as seen in human SCD.

CONCLUSION

A major dysbiosis was observed in SCD patients for bacteria that are known strong pro-inflammatory triggers. The Townes mouse showed dysbiosis as well and might serve as a good model to study gut microbiome modulation and its impact on SCD pathophysiology.

Pneumococcal carriage among sickle cell disease patients in Accra, Ghana: Risk factors, serotypes and antibiotic resistance

BACKGROUND

Pneumococcal carriage is the precursor for development of pneumococcal disease, and is also responsible for transmission of the organism from person-to-person. Individuals with Sickle Cell Disease (SCD) are more likely to develop invasive disease with S. pneumoniae compared to their healthy counterparts and the presentation of disease in the former is usually abrupt and severe. In Africa, little is known about the pneumococcus in relation to people with SCD Sickle Cell Disease (SCD). The aim of the study was to investigate the epidemiology of pneumococcal carriage among SCD patients including the carriage prevalence, risk factors, serotypes and antibiotic resistance.

METHOD

This was a cross sectional study involving 402 SCD patients recruited from Korle Bu Teaching Hospital and Princess Marie Louis Hospital in Accra from October 2016 to March 2017. The study subjects included 202 children of the age groups: ≤5 years (94), >5-9 years (75), ≥10-13 years (33) and 200 adults of the age groups: 14-20 years (46), 21-40 years (112), 41-60 years (25), ≤ 61 years (17). Nasopharyngeal (NP) swabs were collected from the study participants as well as epidemiological data on demographic, household and clinical features. The NP specimens were cultured for S. pneumoniae and the isolates were serotyped by latex agglutination. Antimicrobial susceptibility tests of the isolates were done by the disc diffusion test and E-test.

RESULTS

Prevalence of S. pneumoniae carriage among children and adult SCD patients enrolled in the study were 79/202 (39.1%; 95% CI: 32.3 to 46.2) and 20/200 (10.0%; 95% CI: 6.2 to 15.0) respectively. Risk factors associated with pneumococcal carriage were age (OR = 1.137; 95% CI: 1.036-1.248; p = 0.007) and runny nose (OR = 5.371; 95% CI: 1.760-16.390; p = 0.003). Overall, twenty-six pneumococcal serotypes were isolated from the study participants and the predominant serotype was 6B (10.6%), followed by 23B (8.2%). Among the children, serotype coverage of the 13-valent Pneumococcal Conjugate Vaccine, which is currently used in Ghana was 32.4%. Prevalence of penicillin resistance among the pneumococcal isolates was 37.4% (37/99) and all the penicillin-resistant isolates exhibited intermediate penicillin resistance with the exception of one isolate that showed full resistance and was susceptible to ceftriaxone. Prevalence of resistance to the other antibiotics ranged from 2.5% (levofloxacin) to 85% (cotrimoxazole). Multidrug resistance occurred among 34.3% (34/99) of the pneumococcal isolates.

CONCLUSION

Pneumococcal carriage was four-fold higher in SCD children than adults and was characterized by predominance of non-vaccine serotypes and considerable level of multidrug resistance, though penicillin, cefotaxime and levofloxacin resistance appeared to be very low.

Pathology image of the month: death in a young adult with sickle cell disease

A 27-year-old African-American female with known sickle cell disease was admitted for sickle cell crisis and presumed sepsis. The patient's past medical history was complicated by multiple sickle cell-related complications, including seizures and multiple prior blood transfusions. Her hospital course included Staphylococcus epidermidis bacteremia, for which broad spectrum antibiotics were prescribed. On hospital day nine, the patient was found unresponsive and declared dead after unsuccessful efforts at resuscitation. An unlimited autopsy examination was conducted under authorization of the coroner. Findings included numerous pathologic features ascribed to sickle cell disease, including systemic siderosis and splenic atrophy [weight 10 gm (140±78)], fibrosis, and Gamna Gandy nodules. Additional autopsy findings included cardiomegaly with a heart weight of 450 gm (312±78), right atrial and right ventricular chamber dilatation, and hepatomegaly with a liver weight of 2650 gm (1475±362). The image below demonstrates microscopic examination of the lung parenchyma.

Complications of implantable venous access devices in patients with sickle cell disease

Implantable venous access devices (VADs) are used in sickle cell disease (SCD) for patients with poor venous access to facilitate chronic blood transfusions and manage acute complications. We attempted to define the frequency of bloodstream infections (BSI) and thrombosis in adults and children with SCD and VADs. We performed a single-institution, retrospective review of VAD-associated infection and thrombosis in patients with SCD. Thirty-two patients (median age 20 years, range, 1-59) had 86 VADs placed (median, 2.7 VADs per patient, range, 1-7) with a total of 41,292 catheter days (median, 1,376 days; range, 323-3,999). Mean catheter lifespan in adults (691 days ± 123) was not significantly higher than children (614 days ± 154). A total of 66 VAD-associated BSI (1.59 infections per 1,000 catheter days) occurred in 17 of 32 (53%) patients. Children with VADs had fewer BSI (3 of 10; 30%) than adults (14 of 22; 64%, P = 0.08). 24 catheter-associated thromboses (0.49 thromboses per 1,000 catheter days) occurred in 10 of 32 (41%) of patients. Children also had fewer VAD-associated-thrombosis (1 of 10; 10%) than adults (9 of 22; 40%, P = 0.08). In conclusion, the use of VADs in SCD was linked to a significant rate of infection and thrombosis.

Bacteroides fragilis bacteremia associated with vertebral osteomyelitis in a sickle cell patient

Osteomyelitis and septic arthritis are serious complications of sickle cell disease which occur at rates of 18% and 7%, respectively. In two small studies of osteomyelitis in sickle cell patients, the most common causative organisms were Salmonella spp. and Staphylococcus spp. Anaerobic infection is uncommon. Here, we report an 18-year-old girl with sickle cell disease and suspected spontaneous vertebral osteomyelitis due to Bacteroides fragilis. The diagnosis was based on multiple positive blood cultures. Despite extensive investigation, the port of entry could not be determined. The patient responded well to a four-week therapy with metronidazole, without the need for surgical debridement.

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.

HLA-E*0101 allele in homozygous state favors severe bacterial infections in sickle cell anemia

Severe bacterial infections are the major causes of morbidity and mortality in sickle cell anemia (SCA) but are poorly explained. The distribution of a bi-allelic polymorphism (Arg107Gly) of human leukocyte antigen-E (HLA-E) locus was investigated in 144 SCA patients, most of whom originated from from sub-Saharan Africa. Among them, 73 presented with at least one severe bacterial infection, whereas 71 did not. The HLA-E*0101/E*0101 genotype was more frequent among the group with infections than their counterparts (47% vs 21%; p corrected = 0.003). This genetic association is of relevance, given the emerging evidence for the involvement of HLA-E molecules in host response to pathogens.

Quinupristin-dalfopristin nonsusceptibility in pneumococci from sickle cell disease patients

Sickle cell disease (SCD) is a risk factor for fatal pneumococcal infection. Nonsusceptibilty to quinupristin-dalfopristin (Q-D) was absent from 105 non-SCD-associated pneumococcal isolates but was present in 33/148 (22%) SCD-associated isolates. One-third of the isolates harbored a known resistance mechanism. Q-D is not optimal for use for the treatment of pneumococcal infection in SCD patients.

Unusual sites of Salmonella osteoarthritis in patients with sickle cell disease: two cases

Salmonella osteoarticular infections involve mainly long bones such as the femur, tibia, and humerus in patients with sickle cell disease (SCD). We report here two unusual cases of Salmonella osteoarthritis affecting sacroiliac and sternoclavicular joints in two patients with SCD, one patient also being followed for rheumatoid arthritis. Because of misleading presentation, diagnosis of septic osteoarthritis in patients with SCD requires a high index of suspicion and an early treatment.

Cephalosporin-resistant pneumococci and sickle cell disease

Increasingly resistant bacteria in sickle cell disease patients indicate need to evaluate extendedspectrum cephalosporin therapy.

Sickle cell anemia patients have 600 times the risk for invasive pneumococcal disease than their healthy peers. High-level cephalosporin resistance was described in the 1990s in healthy children from Tennessee, but its prevalence in sickle cell disease patients is unknown. Pneumococcal isolates from sickle cell disease patients from Tennessee were subjected to multilocus sequence typing to characterize antimicrobial drug–resistant strains. Twenty-one percent of strains were resistant to cefotaxime and penicillin. Of the 14 cephalosporin-resistant strains, 9 were sequence types previously described as highly cephalosporin resistant, while resistance was found for the first time in 3 clones: Maryland^6B, ST660, and a novel clone, ST1753. High-level cephalosporin resistance exists in more settings than initially recognized, and its high prevalence in sickle cell disease patients may decrease the efficacy of third-generation cephalosporins in invasive pneumococcal disease.

Association of the G-463A myeloperoxidase polymorphism with infection in sickle cell anemia

Infections constitute a principal cause of morbidity and mortality in sickle cell anemia (SCA). Here we present evidence to suggest that a polymorphism (G-463A MPO) in the gene encoding the myeloperoxidase (MPO) enzyme, important for the host defense system, may significantly increase susceptibility to infection in SCA.

[Infection in sickle cell disease]

Bacterial infection is frequent in patients with sickle cell disease. Pneumococcal bacteremia is particularly severe in young children. The risk persists in adults, especially for nosocomial infections. Prevention is directed against pneumococcal disease and includes both vaccination and prophylactic antibiotics.

Serum procalcitonin concentration as a negative predictor of serious bacterial infection in acute sickle cell pain crisis

BACKGROUND

A pilot study was designed to determine if serum procalcitonin levels would assist in the diagnosis of severe bacterial infections in patients presenting to an emergency department (ED) with acute sickle cell pain crisis and evidence of acute inflammatory response.

MATERIAL/METHODS

Prospective single cohort study evaluating measured procalcitonin levels in patients with sickle cell pain crisis and evidence of acute inflammation. Acute inflammation was defined as fever (>38 degrees C) and/or elevation in the white blood cell count (>4000 above baseline) and tachycardia (heart rate >100). Procalcitonin was measured using a semi-quantitative monoclonal antibody test. Patients were followed clinically to determine if procalcitonin has predictive value in excluding severe bacterial infections.

RESULTS

Twenty four subjects were enrolled and completed the study. Sixteen had levels 0.5 ng/ml or less, two had levels 0.5 to 2 ng/ml, one had a level of 2 but less than 10 ng/ml, and four had levels 10 ng/ml or greater. All subjects with documented infections at presentation had procalcitonin levels > or =2.0 ng/ml. The sensitivity of the test in this study sample was 1, and the specificity was 0.95 (95% CI, 0.75-0.99).

CONCLUSIONS

A serum procalcitonin less than 2 ng/ml appears to have good negative predictive value in excluding serious bacterial infections in patients that present with acute sickle cell pain crisis and evidence of acute inflammatory response. Further study is needed to investigate if procalcitonin has positive predictive value in identifying patients with serious bacterial infections in this patient population.

Urinary tract infection in febrile children with sickle cell anaemia in Ibadan, Nigeria

A prospective study to determine the prevalence of bacteriuria and bacterial isolates in the urine of febrile children with sickle cell anaemia (SCA) was carried out at University College Hospital, Ibadan. Altogether, 171 febrile children (aged 1-15 years) with SCA and 171 age- and sex-matched controls were studied. After obtaining a history of the illness from the parents or guardians, each child was physically examined and a mid-stream urine specimen collected and subjected to microscopy and culture. The prevalence of bacteriuria in children with SCA was 21.6% compared with 15.8% in the controls. Escherichia coli and Klebsiella species were the predominant isolates from the urine, accounting for 64.9% and 18.9%, respectively, of the isolates from the SCA group and 63% and 22.2%, respectively, in the controls. In the SCA group, significant bacteriuria also occurred with other conditions such as pneumonia and osteomyelitis. Urinary tract infection (UTI) is common in children with SCA. Routine screening for it is therefore recommended during febrile illnesses. Children with fever from other overt causes, however, should not be exempted from the urine screening procedure in case there might be concomitant UTI.

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.

Leg ulcer due to Pseudomanas luteola in a patient with sickle cell disease

Pseudomonas luteola is rarely implicated in clinical infections, usually in association with indwelling catheters or prostheses. This report describes the first case of deteriorated leg ulcer caused by a multiply antibiotic resistant P. luteola strain in a patient with homozygous sickle cell disease.

MRSA pyomyositis complicating sickle cell anaemia

A patient being treated for sickle cell crisis developed swollen, painful, indurated, discoloured thighs after several days in hospital. Imaging revealed the presence of multiple small abscesses in the muscle and methicillin resistant Staphylococcus aureus (MRSA) was cultured from aspirated fluid. Pyomyositis usually occurs in association with damaged muscle and impaired host defences. Staphylococcus is the most frequent organism involved. It is not a common complication of sickle cell disease, although it may be under diagnosed. Availability of advanced imaging techniques facilitates early diagnosis of pyomyositis.

[Severe infections in children with sickle cell disease: clinical aspects and prevention]

Sickle-cell disease (SCD) is associated with frequent and often severe infections as a result of immune function impairment and functional asplenia. Also, infection can trigger a vasoocclusive crisis. Pneumonococcal bacteremia and meningitis due to S. pneumoniae are often lethal and justify the penicillin prophylaxis, which has provided a dramatic decrease in early mortality bacterial pneumonia is common in patients younger than four years, with most cases being due to S. pneumoniae, H. influenzae, Mycoplasma pneumoniae, Chlamydia pneumoniae. Acute chest syndrome is both a difficult differential diagnosis and a common concomitant of bacterial pneumonia, because they are often intricated. Osteomyelitis is generally due to Salmonella, most often S. enteritidis. Multiple foci are common and treatment is difficult, with some patients developing chronic osteomyelitis with sequestration. Osteomyelitis is less frequent in developed countries and must been differentiated with bone infarction by use of bone scintigraphy. Parvovirus B19 infection causes acute erythroblastopenias. Malaria does not result in cerebral malaria, but can lead to severe anaemia or vasoocclusive crisis, and should therefore be effectively prevented. Antimicrobials are generally selected for efficacy against pneumococci (septicemia, meningitis), Salmonella (osteomyelitis, meningitis), and M. pneumoniae (pneumonia). Prophylactic therapy is of paramount importance and relies on long-term or lifelong penicillin therapy started at three months of age and no closely-spaced immunizations, most notably against peumococci, hepatitis B virus, S. typhi and H. influenzae. Resistant pneumococcal strains have not been reported to cause prophylactic treatment failures. New conjugated pneumococcal vaccines are effective in protecting very young infants and should therefore be used in sickle cell patients.

Bordetella holmesii isolated from a patient with sickle cell anemia: analysis and comparison with other Bordetella holmesii isolates

OBJECTIVES

To analyze a Bordetella holmesii isolate from a patient with sickle cell anemia and to compare it with other B. holmesii strains and isolates and with strains of B. pertussis and B. bronchiseptica, two well-characterized species of the Bordetella genus.

METHODS

The bacteriological characteristics and proteins produced by the B. holmesii isolate and the reference strain (ATCC 51541) were analyzed and compared with those of B. pertussis and B. bronchiseptica using sera from patients infected with B. pertussis, B. bronchiseptica or B. holmesii.

RESULTS

The bacteriological characteristics of the B. holmesii isolate studied here were similar to those of the B. holmesii reference strain and other isolates. Some of the proteins produced by B. holmesii isolates were similar to those produced by B. pertussis and B. bronchiseptica, but none of these proteins was similar to the toxins and adhesins involved in the pathogenicity of B. pertussis and B. bronchiseptica. The phenotypic diversity of the proteins produced by B. holmesii isolates and the reference strain was striking.

CONCLUSIONS

Our results suggest that either, the expression of B. holmesii proteins is regulated as in B. pertussis and B. bronchiseptica, with the B. holmesii strain exhibiting different phases, or the proteins produced in B. holmesii are different.

Rheumatic manifestations of infectious diseases in children

Infectious diseases continue to elicit worldwide attention. Many of these diseases have rheumatic manifestations as an incidental or principal feature. Because this is particularly true in children, rheumatic manifestations of infectious diseases in this population continue to be an area of great importance to rheumatologists. A variety of bacteria, viruses, fungi, and parasitic organisms can give rise to infectious diseases with rheumatic manifestations. A high index of clinical suspicion is frequently necessary for an accurate diagnosis. Prompt diagnosis and early and appropriate therapeutic intervention are usually required for a successful, and frequently curative, outcome. Over the past year, studies have addressed the pathogenetic mechanisms and clinical spectrum of the rheumatic manifestations of infectious diseases in children. There has been particular emphasis on septic arthritis, osteomyelitis, sickle-cell disease, and hepatitis C viral infection. There remains the daunting and unfortunate possibility of large numbers of children developing HIV-associated arthritis.

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.

Nasopharyngeal carriage of penicillin-resistant Streptococcus pneumoniae in children with sickle cell disease

OBJECTIVE

We studied the prevalence of nasopharyngeal (NP) carriage, antimicrobial susceptibilities, and serotypes of Streptococcus pneumoniae (SP) in children with sickle cell disease (SCD) in the Mid-South. In addition, we examined risk factors for NP carriage of penicillin-resistant SP (PRSP).

STUDY DESIGN

Between July 1994 and December 1995, we obtained NP cultures from 312 children with SCD followed at the Mid-South Sickle Cell Center, 208 (67%) of whom were receiving penicillin prophylaxis.

RESULTS

Among the 312 patients, colonization with SP occurred in 42 (13%), 30 (71%) of whom were receiving penicillin prophylaxis. Twenty-three of the 42 SP isolates (55%) were resistant to penicillin; 5 of the 23 (22%) were highly resistant. PRSP organisms were also resistant to cefotaxime (43%), trimethoprim-sulfamethoxazole (57%), and erythromycin (22%). Serotypes 6A, 6B, 14, 19A, and 23F accounted for 19 (90%) of 21 resistant strains. Children who were treated with antibiotics during the preceding month were more likely to carry PRSP than children who were not treated.

CONCLUSIONS

There is a high prevalence of NP carriage of PRSP in children with SCD in the Mid-South, which raises concerns regarding the continued effectiveness of penicillin prophylaxis in these children. Further studies on the antimicrobial susceptibilities of resistant organisms and the relationship between NP carriage of SP and invasive disease are needed before developing new recommendations for prophylaxis and treatment.

Pneumococcal colonization in children with sickle cell disease [see comment]

OBJECTIVE

The goals of this prospective study were to define the Streptococcus pneumoniae colonization rate in children with sickle cell disease (SCD) at the Children's Hospital of Philadelphia and to determine the serotype and antibiotic susceptibility of all isolates.

METHODS

Children with SCD followed at the hospital were sampled for colonization with S. pneumoniae by means of a throat or nasopharyngeal swab on one or two occasions. Patient information was obtained when the specimen was collected. Specimens were isolated on gentamicin-blood agar plates and modified Avery broth. Antibiotic susceptibility was determined by a commercially available test (E-test). Isolates were serotyped with the use of type-specific antisera. The relationship between the data noted above and certain clinical parameters was examined.

RESULTS

A total of 490 specimens were obtained from 278 patients. Twenty-eight patients had a culture positive for S. pneumoniae, resulting in an overall colonization rate of 10%. Thirty-three percent (11/33) of all isolates were resistant to penicillin-seven intermediately resistant and four highly resistant. Twelve percent of isolates were also resistant to cefotaxime. Eight different serotypes were identified; all but one are included in the current 23-valent pneumococcal vaccine. Penicillin prophylaxis did not increase the rate of colonization with resistant strains of pneumococcus.

CONCLUSION

Our results do not support a change in the current use of penicillin prophylaxis nor in the acute management of the febrile child with SCD.

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.

Colonization with antibiotic-resistant Streptococcus pneumoniae in children with sickle cell disease

OBJECTIVE

Because of susceptibility to severe pneumococcal infection, children with sickle cell disease (SCD) routinely receive penicillin prophylaxis. Increasing rates of penicillin resistance have been reported throughout the world. Our objective was to assess the prevalence of nasopharyngeal colonization with Streptococcus pneumoniae and to assess the antimicrobial susceptibility of the organisms in children with SCD.

STUDY DESIGN

Nasopharyngeal cultures for S. pneumoniae were obtained from all children with SCD attending clinics in a statewide university-based network. Background colonization rates were determined in children attending day care centers in some of the same locations. All recovered S. pneumoniae organisms were tested for susceptibility to penicillin, and all resistant strains were examined for susceptibility to other antibiotics.

RESULTS

Overall nasopharyngeal pneumococcal colonization rates among children with SCD were 12%. Colonization was associated with age less than 2 years (p <0.001) and day care attendance for more than 20 hr/wk (p = 0.00005). More than half of these strains (62%) were resistant to penicillin, 33% having intermediate resistance (minimal inhibitory concentration 0.06 to 1 microgram/ml) and 29%, high level resistance (minimal inhibitory concentration > or = 2.0 microgram/ml). Penicillin resistance was associated with penicillin prophylaxis (p <0.01). Many of these organisms were also resistant to other classes of antibiotics.

CONCLUSIONS

Although penicillin prophylaxis and pneumococcal vaccine for patients with SCD have reduced overall nasopharyngeal colonization and disease caused by S. pneumoniae (p <0.001), a higher percentage of colonizing strains are now resistant both to penicillin and to other antimicrobial agents (p <0.01). Newer strategies for preventing disease and early management of suspected pneumococcal infection in these children must be developed.

Pseudomonas vesicularis causing bacteremia in a child with sickle cell anemia

Pseudomonas vesicularis is a gram-negative rod infrequently found in environmental sources or clinical specimens. We report a case of bacteremia due to Pseudomonas vesicularis in a child with sickle cell anemia, fever, and pneumonia. This is the first published report of invasive P vesicularis in a child.

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.

Polymicrobial polyfocal osteomyelitis and polymicrobial urinary tract infection in sickle cell disease--a case report

Salmonella osteomyelitis is a well-known association of patients with sickle cell disease. This case report describes an infant with osteomyelitis having multiple foci and two pathogens including Salmonella and Staphylococcus aureus who was treated successfully. An additional unusual feature included urinary tract infection.

Acute splenic sequestration together with aplastic crisis caused by human parvovirus B19 in patients with sickle cell disease

Three children with homozygous sickle cell disease, 22 months and 8 and 10 years of age, had clinical and hematologic manifestations of aplastic and splenic sequestration crisis simultaneously. They had an acute drop in hemoglobin level (16, 20, and 45 gm/L), reticulocytopenia (0.1%, 0.6%, and 0.3%), and sudden splenic enlargement. Evidence of recent parvovirus infection was demonstrated.

Pattern of bacteraemia in febrile children with sickle cell anaemia

A total of 166 episodes of fever in 162 children with sickle cell anaemia (SCA) aged between 6 months and 16 years who presented with rectal temperatures > or = 38.3 degrees C were studied for bacteraemia. Non-sicklers of similar ages and with similar temperatures were also studied as controls. Bacteraemia occurred in 32.5% (54) of children with SCA and in 26% (39) of controls. Gram-negative bacteria were the predominant organisms (70.4%) in SCA. The commonest organisms isolated were Salmonella (25.9%), Klebsiella (25.9%) and Staphylococcus aureus (22.2%). Gram-positive bacteria were the predominant organisms (51.3%) in controls, with Staphylococcus aureus accounting for 41% of all organisms isolated. In both groups, the incidence of bacteraemia decreased in children after the age of 10 years. Use of antibiotics prior to presentation in hospital was commoner among children with SCA (47.6%) than controls (14.7%). Antimicrobial agents were detected in the urine of 12 children with SCA and four controls whose parents denied prior antibiotic usage. The predominant organisms isolated were sensitive to gentamicin and 3rd-generation cephalosporins.

Transient aplastic crisis in patients with sickle cell disease. B19 parvovirus studies during a 7-year period

OBJECTIVE

To determine (1) the proportion of cases of transient aplastic crisis (TAC) in patients with sickle cell disease due to B19 parvovirus infection in several years, (2) longitudinally, the immune response to B19 parvovirus infection, and (3) whether patients with sickle cell disease experience recurrent or chronic B19 parvovirus infection.

DESIGN

Prospective evaluation of patients with sickle cell disease and TAC to find evidence of B19 parvovirus infection and, if present, to document the pattern of serologic response with time.

SETTING

Large urban teaching hospital.

PATIENTS

Patients younger than 18 years with sickle cell disease who were admitted to the hospital with a diagnosis of TAC or who developed TAC while in the hospital for other reasons. Follow-up serologic studies of B19 parvovirus infection were done in eight patients.

MEASUREMENTS/MAIN RESULTS

Serum was tested for B19 parvovirus DNA/viral particles and specific anti-B19 parvovirus IgM and IgG antibodies. B19 parvovirus DNA/viral particles were detected in 11 (21%) of 53 patients with TAC. Specific anti-B19 parvovirus IgM antibodies were detected in 34 (64%) of the 53 patients. Overall, 36 (68%) of 53 patients with TAC had evidence of acute B19 parvovirus infection as shown by the detection of B19 DNA parvovirus and/or specific anti-B19 parvovirus IgM antibodies in acute-phase serum. Follow-up serologic studies in eight patients with acute infection revealed disappearance of B19 parvovirus DNA/viral particles and anti-B19 parvovirus IgM antibodies and persistence of anti-B19 parvovirus IgG antibodies for up to 3 1/2 years after the diagnosis of acute B19 parvovirus infection. No patient had evidence of recurrent or chronic B19 parvovirus infection.

CONCLUSIONS

Approximately 70% of cases of TAC in patients with sickle cell disease identified in a 7-year period were caused by acute B19 parvovirus infection. Once detected, anti-B19 parvovirus IgG antibodies remain detectable for several years. There was no evidence of chronic or recurrent B19 parvovirus infection in patients with sickle cell disease.

Severe pneumococcal sepsis and meningitis in human immunodeficiency virus-infected adults with sickle cell disease

Pneumococcal infection is frequent in children with sickle-cell disease (SCD) but is less common in adults. Infection due to human immunodeficiency virus (HIV) is also a risk factor for pneumococcal infection. The purpose of this study was to determine the clinical course of HIV infection in adults with SCD. During a 6-year period, 283 adults suffering from SCD were screened for HIV type 1 and HIV type 2 infections. The clinical course of HIV infections in these patients was retrospectively analyzed at the term of the study. HIV type 1 infection was detected in eight patients. The mean follow-up period after diagnosis of HIV infection was 4.6 years. None of the patients had AIDS. Five episodes of severe pneumococcal infection were observed in four of these eight patients (septic shock in two patients and three episodes of meningitis in two patients); two patients died of meningitis. Only one severe pneumococcal infection (meningitis) was observed in the 275 non-HIV-infected patients with SCD (P = .000001). Our results show that pneumococcal infection appears to occur frequently and is often serious in HIV-infected adults with SCD.

Microbial flora and its significance in pathology of sickle cell disease leg ulcers

The microflora and its significance was investigated in 82 leg ulcers in patients with sickle cell disease. Staphylococcus aureus, Pseudomonas aeruginosa and group A streptococci were the most common isolates. The majority of ulcers which yielded these organisms showed signs of local inflammation, regional lymphadenopathy and healed slowly as compared with ulcers which did not show these organisms. Repeat culture swabs demonstrated persistence of these organisms. A topical spray containing neomycin, polymyxin B and bacitracin helped to eradicate these organisms and hastened the healing process of ulcers. Coliforms and anaerobes were also isolated but were transient in nature and of no significance in the pathology of such ulcers.

Role of Chlamydia pneumoniae in acute chest syndrome of sickle cell disease

Children with sickle cell disease and acute chest syndrome were investigated for infection with Chlamydia pneumoniae and Mycoplasma pneumoniae. Of 30 patients who had 32 episodes of acute chest syndrome, four (13%) had C. pneumoniae isolated from the nasopharynx; two of these also had serologic evidence of acute infection, and one had positive nasopharyngeal isolates on two subsequent occasions during the course of 1 year with stable, elevated titers of anti-C. pneumoniae IgG, suggesting chronic infection. Two patients with negative cultures had serologic evidence of infection with C. pneumoniae. None of 32 cultures for M. pneumoniae were positive, and although anti-M. pneumoniae IgM developed in two patients, one of these patients had evidence of C. pneumoniae infection (positive culture and seroconversion). We conclude that C. pneumoniae infection is prevalent in our sickle cell population with acute chest syndrome. Until further studies clarify the pathophysiologic significance of C. pneumoniae infection, we believe that early inclusion of erythromycin as antimicrobial therapy for acute chest syndrome seems reasonable.

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.