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

Bone and Joint Infections in Children With Sickle Cell Disease in French Guiana: A 13-year Retrospective Multicenter Review

INTRODUCTION

Sickle cell disease (SCD) is a genetic disorder with a high infectious morbidity and mortality and a heterogeneous distribution in France. One of the challenges is to differentiate a bone and joint infection (BJI) from a vaso-occlusive crisis. This challenge is particularly prevalent in French Guiana, an overseas territory with the highest incidence of SCD in France. The aim of this study was to describe the epidemiology of BJI in children with SCD in French Guiana.

METHOD

This was a retrospective multicentric descriptive study of SCD patients living in French Guiana aged under 18 and diagnosed with a BJI between 2010 and 2022. These BJI were divided into 2 groups: those with microbiological documentation (d-BJI) and those without microbiological identification (ud-BJI).

RESULTS

A total of 53 episodes of BJI in 42 patients (mean age 7.2 years) were reported. Clinical symptoms on arrival were comparable between the d-BJI and ud-BJI groups. Patients in the d-BJI group had longer average hospital stays (40.4 days vs. 16.8 days, P = 0.01) and Salmonella spp. were the most identified bacteria (n = 8/13). White blood cell count was greater in the d-BJI group (30.3 G/L vs. 18.G/L, P = 0.01) and a collection was more frequently identified on imaging (11/13 vs. 16/40, P = 0.01) in this group. Initial in-hospital antibiotic therapy was longer in the d-BJI group (17.2 days vs. 12.8, P = 0.02), as were infection-related complications (9/13 vs. 12/40 P = 0.01).

CONCLUSION

BJI in children with SCD is not sufficiently microbiologically documented. Progress must be made to improve the documentation of BJI.

New Horizons in Emergency Department Management of Pediatric Sickle Cell Disease

ABSTRACT

Sickle cell disease (SCD) is an important topic for emergency medicine audiences because complications of the disease account for a large proportion of hematologic emergencies that are seen in the emergency department each year. Early recognition and aggressive management of emergency complications of SCD can help to reduce the morbidity and mortality associated with this disease. Although the treatment recommendations for some complications of SCD are based on expert opinion, there has been advancement in the understanding of the pathogenesis of the disease and evidence regarding the treatment options available for managing acute complications. This continuing medical education article will provide a summary of the clinical manifestation and management of the most common acute complications of SCD: infection, vaso-occlusive episode, acute chest syndrome, splenic sequestration, stroke, and priapism.

Bacterial Infection in the Sickle Cell Population: Development and Enabling Factors

The high frequency of bacterial infections represents a major threat to public health. In developing countries, they are still responsible for significant morbidity and mortality in pediatric populations with sickle cell disease, particularly in children under 5 years of age. Indeed, they have an increased susceptibility to bacterial infections due to their immune deficiency. This susceptibility is even greater for pneumococcal and salmonella infections. In addition, the underdevelopment of some countries and socio-economic factors increases this condition. This review examines the common and specific factors leading to infections in people with sickle cell disease in different types of developed and undeveloped countries. The threat of bacterial infections, particularly those caused by S. pneumoniae and Salmonella, is of increasing concern due to the rise in bacterial resistance to antibiotics. In light of this disturbing data, new strategies to control and prevent these infections are needed. Solutions could be systematic penicillin therapy, vaccinations, and probabilistic antibiotic therapy protocols.

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.

The genetic basis of pneumococcal and staphylococcal infections: inborn errors of human TLR and IL-1R immunity

Many bacteria can cause pyogenic lesions in humans. Most of these bacteria are harmless in most individuals, but they, nevertheless, cause significant morbidity and mortality worldwide. The inherited and acquired immunodeficiencies underlying these pyogenic infections differ between bacteria. This short review focuses on two emblematic pyogenic bacteria: pneumococcus (Streptococcus pneumoniae) and Staphylococcus, both of which are Gram-positive encapsulated bacteria. We will discuss the contribution of human genetic studies to the identification of germline mutations of the TLR and IL-1R pathways.

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.

Outcomes of febrile events in pediatric patients with sickle cell anemia

BACKGROUND

Limited evidence exists to create institutional admission criteria guidelines for febrile sickle cell patients. In addition, evidence is lacking to understand readmission rates for febrile sickle cell patients discharged from the emergency department (ED) or hospital.

PROCEDURES

We conducted a 16-year retrospective study of bacteremia outcomes for febrile sickle cell patients. Risk variables analyzed included fever (either ≥ 39.5°C or ≥40°C), abnormal white blood cell (WBC) (>30,000 or <5,000/mcL), tachycardia and hypotension, or "ill appearing." Fourteen-day readmission rates were analyzed to determine outcomes for febrile sickle cell patients discharged from the ED or discharged within 72 h.

RESULTS

Bacteremia was identified in 17 (2.6%) of 653 febrile events that are presented to the ED. "Ill-appearing" patients had an 8.5-fold increased odds of being diagnosed with bacteremia. Models using WBC count, "ill appearing," and hypotension have the highest sensitivity and specificity (AUC > 0.75). Among 427 patients discharged from the ED or within 72 h of hospitalization, only 10 (2.3%) were readmitted for a new sickle cell complication.

CONCLUSIONS

Institutions can develop admission criteria based on WBC count, hypotension, and "ill appearance." Persistently febrile, well-appearing patient can be discharged at 48 h with minimal risk for new complications.

Severe, non specific symptoms in non-typhoidal Salmonella infections in adult patients with sickle cell disease: a retrospective multicentre study

BACKGROUND

Non-typhoidal salmonellosis (NTS) often occurs in children with sickle-cell disease (SCD) and remains a significant cause of mortality in developing countries. However, there is lack of reports on the clinical presentation, outcome and complications of NTS in adults with SCD.

METHODS

We performed a chart review between 2006 and 2016 of adults SCD diagnosed with NTS in 3 referral centers monitoring approximately 3500 SCD adults.

RESULTS

Twenty-three episodes of NTS were diagnosed among 22 SCD adults. Diagnosis was challenging: 65% (n = 15/23) of patients presented with vaso-occlusive crisis (VOC) and 30% had no fever. Isolated serotypes were: ser. Enteritidis (n = 8), ser. Typhimurium (n = 6), others (n = 3). We identified two patterns of infections: (1) bacteremic NTS (n = 15) with (n = 9) or without secondary foci of infections (n = 6); (2) non-bacteremic NTS with extra-intestinal foci of infection (n = 8), including primary bones/joints infections (n = 5). Half of patients with osteo-articular localization (n = 6/13) had a previous history of osteonecrosis (n = 2) or osteomyelitis (n = 4) at the same site. Morbidity was high, 6 patients (26%) were admitted to the intensive care unit, 14 patients (61%) required RBC transfusion for VOC. Half of the episodes (n = 12) required surgery (n = 10) or interventional radiology (n = 2) to control the infection. One patient presented a relapse of NTS bacteraemia one year after the first episode.

CONCLUSIONS

Besides bloodstream infections, clinical presentation of NTS in adults with SCD is non-specific at admission. A triad including bacteraemia, secondary focis of infection and bone localizations was observed in 30% of cases.

Outpatient Management of Febrile Children With Sickle Cell Disease

The electronic medical records at 2 children's hospitals were reviewed from June 1, 2011 to May 31, 2013 for all patients with sickle cell disease who presented with fever. Of a total of 390 blood cultures drawn, 11 cultures (2.8%) turned positive with only 1 (0.3%) growing a true pathogen. This culture turned positive in 13 hours. There were 154 patients who received exclusive outpatient management of fever. Fourteen patients (9.1%) completed 1 acute care visit, 16 patients (10.4%) completed 2 acute care visits, and 124 patients (80.5%) completed 3 acute care visits. Of those treated exclusively as outpatients, there was 1 positive culture that was considered a contaminant. Although the overall rate of positivity was low, this study confirms previous findings that pediatric blood cultures become positive with pathogens within 48 hours. Given the high rate of compliance and early time to positivity of true pathogens, we suggest that follow-up for the febrile sickle cell disease patients can be treated on an outpatient basis.

Impairment of neutrophil oxidative burst in children with sickle cell disease is associated with heme oxygenase-1

Sickle cell disease is a risk factor for invasive bacterial infections, and splenic dysfunction is believed to be the main underlying cause. We have previously shown that the liberation of heme in acute hemolysis can induce heme oxygenase-1 during granulopoiesis, impairing the ability of developing neutrophils to mount a bactericidal oxidative burst, and increasing susceptibility to bacterial infection. We hypothesized that this may also occur with the chronic hemolysis of sickle cell disease, potentially contributing to susceptibility to infections. We found that neutrophil oxidative burst activity was significantly lower in treatment-naïve children with sickle cell disease compared to age-, gender- and ethnicity-matched controls, whilst degranulation was similar. The defect in neutrophil oxidative burst was quantitatively related to both systemic heme oxygenase-1 activity (assessed by carboxyhemoglobin concentration) and neutrophil mobilization. A distinct population of heme oxygenase-1-expressing cells was present in the bone marrow of children with sickle cell disease, but not in healthy children, with a surface marker profile consistent with neutrophil progenitors (CD49d(Hi) CD24(Lo) CD15(Int) CD16(Int) CD11b(+/-)). Incubation of promyelocytic HL-60 cells with the heme oxygenase-1 substrate and inducer, hemin, demonstrated that heme oxygenase-1 induction during neutrophilic differentiation could reduce oxidative burst capacity. These findings indicate that impairment of neutrophil oxidative burst activity in sickle cell disease is associated with hemolysis and heme oxygenase-1 expression. Neutrophil dysfunction might contribute to risk of infection in sickle cell disease, and measurement of neutrophil oxidative burst might be used to identify patients at greatest risk of infection, who might benefit from enhanced prophylaxis.

Fever in children with sickle cell disease: are all fevers equal?

BACKGROUND

Sepsis is the most common cause of mortality in sickle cell disease (SCD). Empiric antibiotic administration after obtaining blood cultures in febrile children with SCD has been a standard practice parameter.

OBJECTIVE

Our primary objective was to calculate the rate of bacteremia in febrile pediatric patients with SCD. Our secondary objective was to establish whether vital signs or diagnostics predict bacteremia in these patients.

METHODS

We conducted a retrospective chart review of patients with SCD who presented to an urban pediatric emergency department in Newark, NJ between January 1, 2001 and June 30, 2011 with the chief complaint of fever. Patients between the ages of 0 and 20 years with SCD who presented with the chief complaint of fever and who had a blood culture performed were included. Descriptive data, visit-specific data, and diagnostic data were collected.

RESULTS

Charts of 307 patients were included. Six patients had a positive blood culture, one of which was considered a true pathogen (Streptococcus pneumoniae) (0.33%; 95% confidence interval 0.06%-1.86%). There was no statistical significance between the means of visit-specific and diagnostic data of patients with positive blood cultures and those with negative blood cultures.

CONCLUSIONS

The incidence of bacteremia in febrile children with SCD presenting to the emergency department is low. Close follow-up within 24 hours and delayed antibiotic administration can be a plausible alternative treatment option in this population.

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.

Predictors for bacteremia in febrile sickle cell disease children in the post-7-valent pneumococcal conjugate vaccine era

OBJECTIVES

The objective of this study was to determine the incidence of bacteremia in febrile sickle cell disease (SCD) children before and after the 7-valent pneumococcal vaccine (PCV7), and to determine clinical factors associated with bacteremia following PCV7.

PATIENTS AND METHODS

We reviewed all febrile events in SCD children from 1993 to 2009 at a tertiary care pediatric center, comparing general bacteremia and pneumococcal bacteremia incidence for 3 time periods around the PCV7. Univariate analysis and stepwise logistic regression identified clinical factors most associated with bacteremia in this population.

RESULTS

Of 466 SCD children identified, there were 2504 febrile events. We found 84 cases of bacteremia; 8 were pneumococcal. The general bacteremia incidence decreased significantly from 5.60% to 2.44% (P<0.001) over time. Pneumococcal bacteremia incidence did not decrease (P=0.13). Following PCV7, we identified 4 significant independent risk factors associated with general bacteremia: the presence of a central venous line, higher absolute band count, toxic appearance, and older age.

CONCLUSIONS

In febrile SCD children, the incidence of general bacteremia decreased over time. No decrease in pneumococcal bacteremia was found. The presence of a central venous line, absolute band count, clinical appearance, and age may help predict bacteremia in this population.

Bacteremia risk and outpatient management of febrile patients with sickle cell disease

BACKGROUND AND OBJECTIVES

Previous studies have indicated that febrile children with sickle cell disease (SCD) had a 3% to 5% risk of being bacteremic due to compromised immune function. The introduction of routine penicillin prophylaxis and conjugate vaccines may have lowered the risk of bacteremia. Our goals were to determine the rate of bacteremia among children with SCD per febrile episode and to estimate the safety of outpatient management among these febrile SCD patients.

METHODS

This 18-year retrospective cohort study included febrile SCD patients who presented to Boston Children's Hospital between 1993 and 2010.

RESULTS

A total of 1118 febrile episodes were evaluated. Nine blood specimens had growth of a pathogen in culture (0.8%; 95% confidence interval: 0.3%-1.3%). Of the 466 febrile patients initially managed as outpatients, 3 were bacteremic (0.6%). All 3 received intravenous ceftriaxone at the initial outpatient visit and returned when contacted after growth of bacteria was detected in the blood culture. Upon return to the hospital, none were "ill appearing," required supportive care, or were admitted to an ICU.

CONCLUSIONS

Our rate of bacteremia among febrile children with SCD is much lower than previous estimates, and there was no associated morbidity or mortality among the patients managed as outpatients. A well-appearing febrile child with SCD may be managed as an outpatient after blood is obtained for bacterial culture and parenteral antibiotics are administered, provided there are no other reasons for admission and the patient is able to return promptly for worsening condition or for growth of a pathogen from their blood culture.

Quality-of-care indicators for children with sickle cell disease

OBJECTIVE

To develop a set of quality-of-care indicators for the management of children with sickle cell disease (SCD) who are cared for in a variety of settings by addressing the broad spectrum of complications relevant to their illness.

METHODS

We used the Rand/University of California Los Angeles appropriateness method, a modified Delphi method, to develop the indicators. The process included a comprehensive literature review with ratings of the evidence and 2 rounds of anonymous ratings by an expert panel (nominated by leaders of various US academic societies and the National Heart, Lung, and Blood Institute). The panelists met face-to-face to discuss each indicator in between the 2 rounds.

RESULTS

The panel recommended 41 indicators that cover 18 topics; 17 indicators described routine health care maintenance, 15 described acute or subacute care, and 9 described chronic care. The panel identified 8 indicators most likely to have a large positive effect on improving quality of life and/or health outcomes for children with SCD, which covered 6 topics: timely assessment and treatment of pain and fever; comprehensive planning; penicillin prophylaxis; transfusion; and the transition to adult care.

CONCLUSIONS

Children with SCD are at risk for serious morbidities and early mortality, yet efforts to assess and improve the quality of their care have been limited compared with other chronic childhood conditions. This set of 41 indicators can be used to assess quality of care and provide a starting point for quality-improvement efforts.

Community-acquired Salmonella bacteraemia in patients with sickle-cell disease 1969-2008: a single centre study

We document the aetiology of community-acquired bacteraemia in sickle-cell disease (SCD) patients and present clinical aspects of 11 cases of Salmonella bacteraemia. Prospective computerized records of all significant bacteraemic episodes presenting to our institution from 1969 to 2008 were analysed. Additional clinical information was drawn from hospital medical records. Six thousand three hundred and sixty-nine community-acquired bacteraemic episodes were documented, with 66 occurring in SCD patients. Salmonella species were the third most frequently isolated organism in SCD patients; 18% of bacteraemias in SCD patients were caused by Salmonella species vs 3% in non-SCD patients (p < 0.0001). Moreover, the proportion of community-acquired Salmonella bacteraemic episodes caused by non-Typhi species was significantly higher in SCD compared to other patients (p = 0.0015). Focal infection was identified in 7 of the 11 cases of Salmonella bacteraemia in SCD patients, with bone and joint accounting for 6 of these. Infection may have been acquired during travel to the tropics in 4 patients. Our study supports the view that SCD patients are particularly susceptible to Salmonella infection. These infections frequently require multiple surgical interventions and prolonged hospital stays. SCD patients should be advised to pay particular attention to food hygiene while travelling to the tropics.

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.

Acute bone crises in sickle cell disease: the T1 fat-saturated sequence in differentiation of acute bone infarcts from acute osteomyelitis

AIM

To prove the hypothesis that acute bone infarcts in sickle cell disease are caused by sequestration of red blood cells (RBCs) in bone marrow, and to evaluate the unenhanced T1 fat-saturated (fs) sequence in the differentiation of acute bone infarction from acute osteomyelitis in patients with sickle-cell disease.

MATERIALS AND METHODS

Two studies were undertaken: an experimental study using in-vitro packed red blood cells and normal volunteers, and a retrospective clinical study of 86 magnetic resonance imaging (MRI) studies. For the experimental study containers of packed RBCs were placed between the knees of four healthy volunteers with a saline bag under the containers as an additional control, and were scanned with the pre-contrast T1-fs sequence. Signal intensity (SI) ratios were obtained for packed RBCs:skeletal muscle and packed RBCs:saline. For the clinical study, the SIs of normal bone marrow, packed RBCs, bone and/or soft-tissue lesions, and normal skeletal muscle of 74 patients (86 MRI studies) were measured using unenhanced, T1 fat-saturated MRI. The ratios of the above SIs to normal skeletal muscle were calculated and subjected to statistical analysis.

RESULTS

Fifty-one of 86 MRI studies were included in the final analysis. The ratios of SIs for normal bone marrow, packed red cells, bone infarction, acute osteomyelitis, and soft-tissue lesions associated with bone infarct, compared with normal skeletal muscle were (mean+/-SD) 0.9+/-0.2, 2.1+/-0.7, 1.7+/-0.5, 1.0+/-0.3, and 2.2+/-0.7, respectively. The difference in the ratio of SIs of bone infarcts and osteomyelitis was significant (p=0.003). The final diagnoses were bone infarction (n=50), acute osteomyelitis (n=1), and co-existent bone infarction and osteomyelitis (n=2). Seven patients who had suspected osteomyelitis underwent image-guided aspiration.

CONCLUSION

Acute bone infarcts in sickle cell disease are caused by sequestration of red blood cells in the bone marrow. The unenhanced, T1-fat-saturated sequence alone is diagnostic for acute bone infarcts. Contrast enhancement aids in the diagnosis of acute osteomyelitis. MRI can thus help in early diagnosis, specific treatment, and preventing empirical antibiotic therapy.

Time-to-positivity in patients with Escherichia coli bacteraemia

The time from the start of incubation to a positive reading of blood cultures (time-to-positivity; TTP) is related to the concentration of bacteria in blood. Information concerning the correlation of TTP with clinical parameters, and its usefulness as a prognostic factor in patients with Escherichia coli bacteraemia, is limited. To investigate the relationship of TTP to clinical parameters, 459 cases of monomicrobial E. coli bloodstream infections from a single institution between 1997 and 2005 were reviewed. All cases involved patients who were not undergoing antibiotic treatment at the time of blood sampling. The in-hospital mortality rate was 6.3%. Median TTP was significantly shorter for patients who died than for those who survived (9.7 h, inter-quartile range 7.85-11.05 h vs. 11.2 h, inter-quartile range 10.1-11.4 h; p <0.001). Patients with TTP in the lowest quartile were more likely to be female, to have a non-urinary tract or an unknown origin of bacteraemia, to have severe sepsis or shock, and to subsequently die. In a multivariable Cox regression model, the hazard ratio for death from any cause for patients with a short TTP was 3.13 (95% CI 1.28-7.64; p 0.01). TTP in patients with E. coli bacteraemia provides prognostic information beyond that provided by the presence of haematological illness, a Charlson score > or =3, a non-urinary tract origin of bacteraemia, and the presence of severe sepsis or shock.

Time to blood culture positivity as a predictor of clinical outcome of Staphylococcus aureus bloodstream infection

Few studies have assessed the time to blood culture positivity as a predictor of clinical outcome in bloodstream infections (BSIs). The purpose of this study was to evaluate the time to positivity (TTP) of blood cultures in patients with Staphylococcus aureus BSIs and to assess its impact on clinical outcome. We performed a historical cohort study with 91 adult patients with S. aureus BSIs. TTP was defined as the time between the start of incubation and the time that the automated alert signal indicating growth in the culture bottle sounded. Patients with BSIs and TTPs of culture of </=12 h (n = 44) and >12 h (n = 47) were compared. Septic shock occurred in 13.6% of patients with TTPs of </=12 h and in 8.5% of patients with TTP of >12 h (P = 0.51). A central venous catheter source was more common with a BSI TTP of </=12 h (P = 0.010). Univariate analysis revealed that a Charlson score of >/=3, the failure of at least one organ (respiratory, cardiovascular, renal, hematologic, or hepatic), infection with methicillin-resistant S. aureus, and TTPs of </=12 h were associated with death. Age, gender, an APACHE II score of >/=20 at BSI onset, inadequate empirical antibiotic therapy, hospital-acquired bacteremia, and endocarditis were not associated with mortality. Multivariate analysis revealed that independent predictors of hospital mortality were a Charlson score of >/=3 (odds ratio [OR], 14.4; 95% confidence interval [CI], 2.24 to 92.55), infection with methicillin-resistant S. aureus (OR, 9.3; 95% CI, 1.45 to 59.23), and TTPs of </=12 h (OR, 6.9; 95% CI, 1.07 to 44.66). In this historical cohort study of BSIs due to S. aureus, a TTP of </=12 h was a predictor of the clinical outcome.

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.

Time to positivity in blood cultures of adults with Streptococcus pneumoniae bacteremia

BACKGROUND

previous studies have established that bacterial blood concentration is related with clinical outcome. Time to positivity of blood cultures (TTP) has relationship with bacterial blood concentration and could be related with prognosis. As there is scarce information about the usefulness of TTP, we study the relationship of TTP with clinical parameters in patients with Streptococcus pneumoniae bacteremia.

METHODS

TTP of all cases of Streptococcus pneumoniae bacteremia, detected between January 1995 and December 2004 using the BacT/Alert automated blood culture system in a teaching community hospital was analyzed. When multiple cultures were positive only the shortest TTP was selected for the analysis.

RESULTS

in the study period 105 patients with Streptococcus pneumoniae bacteremia were detected. Median TTP was 14.1 hours (range 1.2 h to 127 h). Immunosuppressed patients (n = 5), patients with confusion (n = 19), severe sepsis or shock at the time of blood culture extraction (n = 12), those with a diagnosis of meningitis (n = 7) and those admitted to the ICU (n = 14) had lower TTP. Patients with TTP in the first quartile were more frequently hospitalized, admitted to the ICU, had meningitis, a non-pneumonic origin of the bacteremia, and a higher number of positive blood cultures than patients with TTP in the fourth quartile. None of the patients with TTP in the 90th decile had any of these factors associated with shorter TTP, and eight out of ten patients with TTP in the 10th decile had at least one of these factors. The number of positive blood cultures had an inverse correlation with TTP, suggesting a relationship of TTP with bacterial blood concentration.

CONCLUSION

Our data support the relationship of TTP with several clinical parameters in patients with Streptococcus pneumoniae bacteremia, and its potential usefulness as a surrogate marker of outcome.

Bloodstream infection in adults with sickle cell disease: association with venous catheters, Staphylococcus aureus, and bone-joint infections

Although well documented in children with sickle cell disease (SCD), the incidence, cause, and outcome of bloodstream infection (BSI) are poorly defined in adults with SCD. Through a 5-year retrospective analysis of a cohort of 900 patients followed at our institution, we identified 56 episodes of BSI in 47 patients. The incidence rate of BSI was 1.2 episodes per 100 patient-years. As compared to the patients followed in the cohort, those with BSI were more likely to be younger (p = 0.001), to have Hb-S disease (p = 0.008), severe disease (p = 0.001), or additional immunosuppression (p = 0.05). BSI was hospital-acquired in 46% of cases and mainly associated with venous catheters (41%) and Staphylococcus aureus (34%). Pneumococci were rarely identified (10.7%). Despite an adequate duration of antibiotic therapy, the course of BSI was marked by a high frequency of associated bone-joint infection. Bone-joint infection was noted in 18 patients (32% of episodes) and occurred either during the initial BSI episode (13 patients) or 1-6 months after BSI resolution (5 patients). Factors associated with the occurrence of bone-joint infection were previous osteonecrosis (relative risk, 2.5; 95% confidence interval, 1.2-5.3) and S. aureus infection (relative risk, 3.8; 95% confidence interval, 1.8-8.4). In conclusion, BSI is a rare event in adults with SCD compared to children. It mainly occurs in those with a severe underlying disease and a venous catheter. These patients have a high risk of associated bone-joint infection and therefore must be closely monitored.

Early bacteremia in pediatric hematopoietic stem cell transplant patients on oral antibiotic prophylaxis

BACKGROUND

Bacteremia occurs during hematopoietic stem cell transplant (HSCT) in 20%-25% of patients and the use of gut decontamination (GD) to decrease this risk is controversial. Our purpose was to determine the incidence of bacteremia and antimicrobial resistance post-HSCT in pediatric patients receiving GD, and to identify risk factors associated with infection.

PROCEDURES

This was a retrospective cohort study of 182 pediatric patients undergoing first HSCT for malignant disease at The Children's Hospital of Philadelphia from January, 1999 to December, 2002. We examined the impact of age, sex, race, diagnosis, disease status, conditioning regimen, recent bacteremia, stem cell source, donor, graft versus host disease prophylaxis agents, and mucositis severity using Cox proportional hazard models. GD consisted of amoxicillin (azithromycin, if penicillin allergic) and oral gentamicin. Outcome was first episode of bacteremia prior to absolute neutrophil count (ANC) 500/mm(3). Antibiotic susceptibilities were performed on all isolates.

RESULTS

Seventy-four patients (41%) developed bacteremia. The majority were Gram-positive cocci, with Staphylococcal (50%) and Streptococcal species (28%) the most common. Gram-negative organisms were identified in 22% with Pseudomonas (5.7%) and Klebsiella species (3.4%) the most common. Of the Streptococcal infections, 72% were resistant to ampicillin; only 25% of the Gram-negative bacteria were resistant to gentamicin. Race was the only factor associated with early bacteremia (hazard ratio 2.3 for non-Caucasian, non-African-American patients, CI 1.3-4.3, P = 0.007).

CONCLUSIONS

Early bacteremia is common after HSCT, despite the use of GD. Resistant Gram-positive organisms predominate, consistent with recent trends in immunocompromised patients. Although used in practice, there is no clear evidence for the efficacy of GD and this study provides the basis upon which to develop a randomized clinical trial evaluating the current GD regimen with placebo.

Primary immunodeficiencies associated with pneumococcal disease

PURPOSE OF REVIEW

Streptococcus pneumoniae may cause disease in patients with a variety of primary immunodeficiencies. However, no previous review has dealt with the issue of which primary immunodeficiencies predispose affected individuals to pneumococcal disease. We thus reviewed the medical literature on cases of S. pneumoniae infection in patients with primary immunodeficiency diseases, with a particular emphasis on invasive pneumococcal disease.

RECENT FINDINGS

Primary immunodeficiency diseases comprise over 100 conditions, each associated with a variety of infections. Patients at high risk for pneumococcal disease include most if not all B-cell defects (whether due to an intrinsic B-cell anomaly or an impaired T-cell help), deficiencies of early components of the classical pathway of complement and C3 deficiency, congenital asplenia, anhidrotic ectodermal dysplasia with immunodeficiency (caused by impaired NF-kappaB activation), and interleukin-1 receptor associated kinase-4 deficiency. Patients with other complement deficiencies (alternative and third pathway) and hyperimmunoglobulin E syndrome show a lower risk, whereas patients with other known primary immunodeficiencies, such as phagocytic disorders, do not appear to be particularly vulnerable to S. pneumoniae.

SUMMARY

Antibody- and complement-mediated opsonization, splenic macrophages and interleukin-1 receptor associated kinase-4- and nuclear factor kappaB-mediated immune responses are crucial for protective immunity to S. pneumoniae. This information is useful, not only in increasing our understanding of human immunity to S. pneumoniae, but also in the diagnostic investigation of patients with pneumococcal disease.

Fever without apparent source on clinical examination

PURPOSE OF REVIEW

Episodes of acute illness associated with fever are common in children. Less common but also diagnostically challenging are episodes of prolonged fever in children. This article reports recent literature that has focused on the epidemiology, pathophysiology, clinical and laboratory evaluation, and treatment of both types of episodes.

RECENT FINDINGS

A number of articles reviewed the epidemiology in several countries of bacteremia in children, including bacteremia caused by Streptococcus pneumoniae and Salmonella sp. Host susceptibility factors for bacterial illness, such as malnutrition, were reported. Diagnostic issues concerning bacteremia, including the technique of venipuncture and urine antigen testing, were of interest. A major study was published that reported a preventive approach through immunization to one type of bacteremia that caused by S. pneumoniae. Other studies addressed the issues of choice of therapy and duration of therapy in selected bacteremic disease, such as dental bacteremias and bacteremia, that were caused by Brucella melitensis. Lastly, several causes of prolonged fever (such as hemophagocytic syndrome and atypical cat scratch disease) were reported.

SUMMARY

During the review period, studies addressed diverse issues related to acute and prolonged episodes of fever in children. There was a particular emphasis on the epidemiology, diagnosis, prevention, and treatment of bacteremic illness in children.