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This chapter explores cerebrospinal fluid (CSF) shunt infections. CSF shunts are critical for many patients surviving congenital central nervous system (CNS) anomalies, infection, or intracranial hemorrhage. Infection is a common complication of these devices and a leading cause of morbidity and hospitalization. Clinical studies performed over the past half-decade have more clearly defined the optimal means to prevent and treat these infections. In patients with suspected CSF shunt infections, initial management includes obtaining CSF from the shunt reservoir or ventricle for diagnostic studies. Patients with presentations suggestive of ventriculitis or meningitis should begin antimicrobial therapy while awaiting these results. Management that includes complete removal of the infected shunt, placement of an extraventricular drain (EVD) if required, intravenous antimicrobials, and shunt replacement once the CSF is sterile, has a success rate of more than 85% and is recommended for most patients with infected CSF shunts.

Background: Skilled healthcare professionals are critical for providing quality healthcare for children with cancer globally. Training curricula addressing the knowledge needs in infection care and prevention (ICP) in cancer are scarce. Program description: We implemented a 10-week blended course in ICP. The distance learning had four 2-week modules: Infectious Complications, Quality in Infection Care, Quality in Infection Prevention, and Sustainability, Research, and Dissemination. Each module had pre- and post-tests and weekly webinars. The 2-week in-person learning had lectures, group exercises, clinical observations, hospital and laboratory tours, and ended in an annual conference. An individual project developed during the distance learning was presented in the in-person workshop. Course attendance criteria were English language proficiency and participants’ role in ICP at their institutions. Program evaluation and results: Twenty-two students from 17 hospitals in 10 countries completed the course, developed a project, and answered surveys covering knowledge assessments and satisfaction, and 6-month course and 1-year project follow-ups. Pretest and post-test scores revealed knowledge improvement ( P Discussion: The ICP course is a resource to improve knowledge, engage graduates in network collaborations, and a reliable model to develop other thematic healthcare global training programs.

Background Management of gram-negative bacteremia (GNB) in children with cancer (CWC) is complicated by increasing rates of antimicrobial resistance. Guidelines for the management of CWC with suspected serious bacterial infections at St. Jude Children’s Research Hospital (SJ) recommend cefepime (CEF) monotherapy for empirical therapy for most patients. Children with evidence of sepsis, recent treatment with CEF or known colonization with a CEF-resistant (CEF-R) organism are initially treated with meropenem and/or amikacin. We compared outcomes of CWC with infections caused by CEF susceptible (CEF-S) and CEF-R bacteria treated according to this algorithm. Methods Demographic information on patients, and clinical and microbiological characteristics of 100 episodes of GNB treated from May 2018 to April 2019 at SJ were retrospectively reviewed. Results Patients’ median age was 8 years; 48% were female. Overall, 46% of patients had leukemia or lymphoma, 40% solid tumors, and 14% were HSCT recipients. Patients were neutropenic [absolute neutrophil count (ANC) Conclusion Over half of the episodes of GNB in this study were caused by CEF-R organisms. Infection with CEF-R organisms was associated with a delay in the administration of effective therapy and greater morbidity, but not greater mortality. Further studies are warranted to clarify the relationship between antimicrobial resistance, disease severity, treatment, and infection outcomes.

Human astroviruses are a major cause of pediatric gastroenteritis, especially in immunocompromised children. We conducted a retrospective study to demonstrate that diverse astrovirus genotypes can co-circulate in pediatric oncology patients. A subset of cases is associated with long-term virus shedding (range 17-183 days).

Broadly multiplexed molecular amplification assays offer an unprecedented ability to diagnose gastrointestinal infection in immunocompromised patients. However, little data are available to compare the performance of such systems in this population. A total of 436 stool samples were collected from 199 predominantly immunocompromised pediatric oncology patients. Remnant samples were tested in parallel with the use of the premarket (investigational use only) versions of two broadly multiplexed PCR assays (BioFire and Luminex), and the results of samples corresponding to the first episode per patient were compared with those from laboratory-developed molecular assays, culture, and antigen detection. Overall performance of the multiplexed systems was comparable, with BioFire and Luminex detecting 94 and 99 positives (P = 0.34), respectively. Stratifying by analyte, BioFire assay detected 51 samples positive for Clostridium difficile, whereas Luminex assay detected 60 (P = 0.01). Biofire and Luminex detected 28 and 38 norovirus-positive samples (P = 0.002), respectively. Astrovirus- and adenovirus-positive samples were detected in higher numbers by in-house PCR than by BioFire; the same was observed for adenovirus with Luminex. Differences observed with other analytes were minimal, did not reach statistical significance, or lacked the numbers needed to detect a difference between systems. Broadly multiplexed PCR offers an effective means of detecting a variety of gastrointestinal pathogens in pediatric oncology patients, with assay performance comparable among the tests examined.

OBJECTIVE. The purpose of this study was to determine whether clinical and imaging features can distinguish osteomyelitis from Ewing sarcoma (EWS) and to assess the accuracy of percutaneous biopsy versus open biopsy in the diagnosis of these diseases. MATERIALS AND METHODS. Three radiologists reviewed the radiographs and MRI examinations of 32 subjects with osteomyelitis and 31 subjects with EWS to determine the presence of 36 imaging parameters. Information on demographic characteristics, history, physical examination findings, laboratory findings, biopsy type, and biopsy results were recorded. Individual imaging and clinical parameters and combinations of these parameters were tested for correlation with findings from histologic analysis. The diagnostic accuracy of biopsy was also determined. RESULTS. On radiography, the presence of joint or metaphyseal involvement, a wide transition zone, a Codman triangle, a periosteal reaction, or a soft-tissue mass, when tested individually, was more likely to be no...

Objectives Health care providers (HCP) are at high risk of acquiring and transmitting pertussis to susceptible family members, co-workers, and patients. Public health authorities recommend administering a single dose of Tdap (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis) vaccine to all adults, including HCP, to increase adult immunity to pertussis. We set a quality improvement goal to increase Tdap vaccination coverage among HCP who provided direct patient care at a children’s hospital from 58% to 90% over 18 months. Design A multidisciplinary working group comprised of Occupational Health Program (OHP) staff and representatives of various medical services drew from a variety of qualitative methods and previous studies of vaccination programs in the healthcare system to understand barriers to Tdap vaccination within the institution and to develop interventions to increase vaccination rates. Interventions Interventions included changes to OHP processes, a general education campaign, improved access to vaccine, and personal engagement of HCP by task force members. Results Overall vaccination rates increased to 90% over 15 months, a rate that has been sustained by systematically assessing new employees’ vaccination status and vaccinating those without documentation of previous Tdap vaccination. Conclusions Tdap vaccination coverage in our institution was significantly increased by an intensive, multipronged educational campaign, and by improving processes of screening and vaccination of HCP. The use of direct engagement of vaccine hesitant populations to increase vaccination rates warrants further study.

Objective The objective of this study was to determine the effectiveness of trivalent inactivated influenza vaccine (TIV) for the prevention of laboratory-confirmed influenza and influenza-like illnesses (ILI) among children and adolescents receiving therapy for acute leukemia. Study design A retrospective review of the demographic and clinical characteristics of 498 patients at a pediatric cancer center who received therapy for acute leukemia during 3 successive influenza seasons (2010-2011 through 2012-2013). Results In 498 patient seasons with a known immunization history (median age, 6 years; range, 1-21), 354 patients (71.1%) were immunized with TIV and 98 (19.7%) received a booster dose of vaccine. Vaccinated and unvaccinated patients had generally similar demographic characteristics. There were no differences in the overall rates of influenza or ILI between vaccinated and unvaccinated patients overall, or in any individual season. There was no difference in the rates of influenza or ILI between patients who received 1 dose of vaccine and those who received 2 doses. Time to first influenza infection and time to first ILI in vaccinated and unvaccinated patients were not different. Conclusion TIV did not protect children and adolescents with acute leukemia against laboratory-confirmed influenza or ILI. Future prospective studies should assess TIV effectiveness in high-risk subpopulations and alternative strategies to prevent influenza should be considered in this population.

Human parainfluenza virus type 1 (hPIV-1) is the most common cause of laryngotracheobronchitis (croup), resulting in tens of thousands of hospitalizations each year in the United States alone. No licensed vaccine is yet available. We have developed murine PIV-1 (Sendai virus [SeV]) as a live Jennerian vaccine for hPIV-1. Here, we describe vaccine testing in healthy 3- to 6-year-old hPIV-1-seropositive children in a dose escalation study. One dose of the vaccine (5 × 105, 5 × 106, or 5 × 10750% egg infectious doses) was delivered by the intranasal route to each study participant. The vaccine was well tolerated by all the study participants. There was no sign of vaccine virus replication in the airway in any participant. Most children exhibited an increase in antibody binding and neutralizing responses toward hPIV-1 within 4 weeks from the time of vaccination. In several children, antibody responses remained above incoming levels for at least 6 months after vaccination. Data suggest that SeV may provide a benefit to 3- to 6-year-old children, even when vaccine recipients have preexisting cross-reactive antibodies due to previous exposures to hPIV-1. Results encourage the testing of SeV administration in young seronegative children to protect against the serious respiratory tract diseases caused by hPIV-1 infections.

Pediatric hematology-oncology and hematopoietic stem cell transplant (HSCT) patients are at high risk of infections, including healthcare-associated infections (HAIs), resulting in a need to prevent these occurrences when possible. Central line-associated bloodstream infections (CLABSI), Clostridium difficile infection (CDI), ventilator-associated pneumonia (VAP), catheter-associated urinary tract infections (CAUTI), and respiratory viral infections are of particular concern, and the incidence, definition, and other features are reviewed. Currently, standard prevention guidelines exist for selected HAIs, and so the prevention approach for each infection must be considered separately. Prevention strategies have emerged through collaborative efforts, as well as measurement of both process and outcome data. Measurement includes surveillance of infection occurrence; identification and reporting of prevention methods, such as bundles; and the outcomes associated with these approaches. These prevention and measurement approaches are only successful when approached collaboratively with engagement across the entire healthcare team. Through continued measurement and process improvement based on the data collected, more sustainable approaches to infection prevention can be developed. With systematic effort, the occurrence of HAI should be reduced, and patient harm will be prevented.

Background Diarrhea is common in children with cancer, but this has not been systematically studied to date. Methods Remnant stool samples collected between January 2010 and June 2011 from pediatric oncology patients with diarrhea were tested for bacterial, viral, and parasitic enteropathogens using a combination of standard-of-care (SOC) diagnostic tests, including broad-range, real-time polymerase chain reaction (PCR) assays for adenoviruses, astroviruses, and sapoviruses and 2 commercially available multiplexed PCR assays. Corresponding demographic and clinical data were abstracted from patients' medical records. Results One hundred fourteen episodes of diarrhea in 93 patients (median age, 3.7 years; range, 0.2-18.8) were included in the study. No patients died, but morbidity was significant. A total of 158 potential pathogens were detected in 114 diarrhea episodes, with >1 organism in one third of these; the most common were Clostridium difficile, noroviruses, adenoviruses, and astroviruses. Clostridium difficile, in combination with norovirus or adenovirus, was most common when >1 pathogen was detected. When both studies were obtained, SOC and broadly multiplexed PCR tests were concordant in 64 episodes (56%). Forty-five pathogens (28%) were identified retrospectively by broadly multiplexed PCR assays only. A total of 19 (13%) were detected by SOC real-time PCR assays but not by either commercially available multiplexed PCR assay. Conclusions Most pediatric oncology patients in this study had 1 or more potential infectious causes for their diarrhea. Additional studies are warranted to understand the natural history of gastroenteritis in this patient population. Although broadly multiplexed PCR assays offer some advantages over conventional testing, there may be disadvantages to their use for the diagnosis of infectious gastroenteritis that are unique to pediatric oncology patients.

Clinical observations and some studies suggest that dengue virus infection is more severe among children with better nutritional status. We examined the nutritional status of children in El Salvador and its relationship between this and the severity of dengue infection. Z-scores for weight-for-age, height-for-age, and body mass index (BMI)-for-age of children with dengue fever (66), dengue hemorrhagic fever (62), and healthy controls (74) were compared. There were no differences in weight-for-age or BMI-for-age Z-scores between the three groups. Children with dengue fever had a greater height-for-age than healthy controls but no significant differences in rates of stunting. There was no difference in height between children with dengue fever and dengue hemorrhagic fever. Excess nutrition does not appear to be a risk factor for severe forms of dengue infection in El Salvador, nor does malnutrition appear to be predictive of good outcomes.

Background: Invasive infections caused by coryneform bacteria are uncommon but have been reported with increasing frequency in recent decades, especially in immunocompromised persons. Because pediatric experience is limited, we examined the epidemiology and clinical characteristics of these infections in children undergoing cancer therapy. Methods: Using strict case definitions, 17 coryneform bacterial infections were identified in 16 children during a 13-year period; there were 12 episodes of bacteremia and 5 skin or soft tissue infections. Results: The median age of children with bloodstream infections was 11.2 years, and that of children with skin or soft tissue infections was 3.5 years. Most were receiving cancer therapy at the time of their infections, were outpatients at the onset of their infections, had central venous catheters, and were not neutropenic. No patient died as a result of infection and most had relatively mild signs and symptoms. All patients responded promptly to antimicrobial therapy and, although 3 infections relapsed, there was only 1 serious complication. The most common species isolated were Corynebacterium striatum, C. amycolatum, and Microbacterium species. Conclusions: The epidemiologic and clinical features of coryneform bacterial infections in immunocompromised children differ in several important respects from the previously reported characteristics of these infections in adults.

Respiratory syncytial virus (RSV) infection is associated with secondary bacterial infections caused by nontypeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae. The pathogenesis of these complications is not completely understood; however, viral infection of respiratory epithelial cells promotes colonization by these bacteria. In the present study, RSV virions associated with NTHi and pneumococci in an inoculum-dependent manner in a fluid-phase binding assay. Adherence of NTHi and S. pneumoniae to epithelial cells transiently expressing RSV G glycoprotein was 2- and 2.2-fold higher, respectively, than adhesion to cells transfected with the vector alone (P P ≤0.005). Pre-incubating cells expressing membrane-bound G protein with blocking anti-RSV G antibodies reduced bacterial adherence by 78–84 % (P ≤0.005). These studies demonstrate that RSV G protein is a receptor for both NTHi and S. pneumoniae. Strategies to prevent this interaction may reduce the incidence of secondary bacterial complications of RSV infection.

The purpose of this study was to determine whether clinical and imaging features can distinguish osteomyelitis from Ewing sarcoma (EWS) and to assess the accuracy of percutaneous biopsy versus open biopsy in the diagnosis of these diseases.Three radiologists reviewed the radiographs and MRI examinations of 32 subjects with osteomyelitis and 31 subjects with EWS to determine the presence of 36 imaging parameters. Information on demographic characteristics, history, physical examination findings, laboratory findings, biopsy type, and biopsy results were recorded. Individual imaging and clinical parameters and combinations of these parameters were tested for correlation with findings from histologic analysis. The diagnostic accuracy of biopsy was also determined.On radiography, the presence of joint or metaphyseal involvement, a wide transition zone, a Codman triangle, a periosteal reaction, or a soft-tissue mass, when tested individually, was more likely to be noted in subjects with EWS (p ≤ 0.05) than in subjects with osteomyelitis. On MRI, permeative cortical involvement and soft-tissue mass were more likely in subjects with EWS (p ≤ 0.02), whereas a serpiginous tract was more likely to be seen in subjects with osteomyelitis (p = 0.04). African Americans were more likely to have osteomyelitis than EWS (p = 0). According to the results of multiple regression analysis, only ethnicity and soft-tissue mass remained statistically significant (p ≤ 0.01). The findings from 100% of open biopsies (18/18) and 58% of percutaneous biopsies (7/12) resulted in the diagnosis of osteomyelitis, whereas the findings from 88% of open biopsies (22/25) and 50% of percutaneous biopsies (3/6) resulted in a diagnosis of EWS.Several imaging features are significantly associated with either EWS or osteomyelitis, but many features are associated with both diseases. Other than ethnicity, no clinical feature improved diagnostic accuracy. Compared with percutaneous biopsy, open biopsy provides a higher diagnostic yield but may be inconclusive, especially for cases of EWS. Our findings underscore the need for better methods of diagnosing these disease processes.

Objectives. We explored whether collective concerns about the safety, effectiveness, and necessity of influenza vaccines mediate racial/ethnic disparities in vaccine uptake among health care workers (HCWs). Methods. We used a self-administered Web-based survey to assess race/ethnicity (exposure), concerns about influenza vaccination (mediator; categorized through latent class analysis), and influenza vaccine uptake (outcome) for the 2012 to 2013 influenza season among HCWs at St. Jude Children’s Research Hospital in Memphis, Tennessee. We used mediation analysis to estimate prevalence ratios (PRs) and 95% confidence intervals (CIs) for the total, direct, and indirect effects of race/ethnicity on influenza vaccine uptake. Results. Non-Hispanic Blacks had lower influenza vaccine uptake than non-Hispanic Whites (total effect: PR = 0.87; 95% CI = 0.75, 0.99), largely mediated by high concern about influenza vaccines (natural indirect effect: PR = 0.89; 95% CI = 0.84, 0.94; controlled direct effect: PR = 0.98; 95% CI = 0.85, 1.1). Hispanic and Asian HCWs had modestly lower uptake than non-Hispanic Whites, also mediated by high concern about influenza vaccines. Conclusions. Racial/ethnic disparities among HCWs could be attenuated if concerns about the safety, effectiveness, and necessity of influenza vaccines were reduced.

Received 6 September 2006; accepted 6 September 2006;electronically published 13 September 2006.Author affiliations are listed at the end of the text.Reprints or correspondence: Dr. Elias J. Anaissie, MyelomaInstitute for Research and Therapy, University of Arkansasfor Medical Sciences, 4301 W. Markham, Slot 816, LittleRock, AR 72205 (anaissieeliasj@uams.edu).

Apoptosis, or programmed cell death (PCD), is an important physiological mechanism, through which the human immune system regulates homeostasis and responds to diverse forms of cellular damage. PCD may also be involved in immune counteraction to microbial infection. Over the past decade, the amount of research on bacteria-induced PCD has grown tremendously, and the implications of this mechanism on immunity are being elucidated. Some pathogenic bacteria actively trigger the suicide response in critical lineages of leukocytes that orchestrate both the innate and adaptive immune responses; other bacteria proactively prevent PCD to benefit their own survival and persistence. Currently, the microbial virulence factors, which represent the keys to unlocking the suicide response in host cells, are a primary focus of this field. In this review, we discuss these bacterial “apoptosis regulatory molecules” and the apoptotic events they either trigger or prevent, the host target cells of this regulatory activity, and the possible ramifications for immunity to infection. Gram-positive pathogens including Staphylococcus, Streptococcus, Bacillus, Listeria, and Clostridia species are discussed as important agents of human infection that modulate PCD pathways in eukaryotic cells.

Group B Streptococcus agalactiae (GBS) is a major cause of neonatal lower respiratory tract infection. Following non-opsonic phagocytosis, GBS trigger programmed cell death of macrophages, early effector cells in the lung. The elimination of macrophages may be an important strategy used by the bacteria to suppress host immune responses and to persist at sites of infection. To better understand GBS-induced programmed cell death, we evaluated mechanisms by which GBS induces apoptosis. Compared to uninfected macrophages, caspase-3 activity of GBS-infected macrophages increased 4.4 ± 2.4 fold (p = 0.009) at 24 h and 1.7 ± 0.7 fold at 48 h following infection and caspase-9 activity increased 1.9 ± 0.01 fold (p = 0.009) at 48 h. GBS-infected macrophages incubated with a caspase-3 specific inhibitor had significantly increased survival compared to infected untreated macrophages. GBS also induced the release of cytochrome c from mitochondria, and depolarization of mitochondrial membrane potentials. This process was associated with increases in the pro-apoptotic protein Bad, and alterations in the regulation and localization of 14-3-3, Bcl-XL and Omi/HtrA2. We conclude GBS induces programmed cell death of macrophages by creating an imbalance in pro- and anti-apoptotic factors that ultimately activates the intrinsic pathway of apoptosis. This mechanism has not been previously associated with microbial infections.

Secondary bacterial infections often complicate respiratory viral infections, but the mechanisms whereby viruses predispose to bacterial disease are not completely understood. We determined the effects of infection with respiratory syncytial virus (RSV), human parainfluenza virus 3 (HPIV-3), and influenza virus on the abilities of nontypeable Haemophilus influenzae and S treptococcus pneumoniae to adhere to respiratory epithelial cells and how these viruses alter the expression of known receptors for these bacteria. All viruses enhanced bacterial adhesion to primary and immortalized cell lines. RSV and HPIV-3 infection increased the expression of several known receptors for pathogenic bacteria by primary bronchial epithelial cells and A549 cells but not by primary small airway epithelial cells. Influenza virus infection did not alter receptor expression. Paramyxoviruses augmented bacterial adherence to primary bronchial epithelial cells and immortalized cell lines by up-regulating eukaryotic cell receptors for these pathogens, whereas this mechanism was less significant in primary small airway epithelial cells and in influenza virus infections. Respiratory viruses promote bacterial adhesion to respiratory epithelial cells, a process that may increase bacterial colonization and contribute to disease. These studies highlight the distinct responses of different cell types to viral infection and the need to consider this variation when interpreting studies of the interactions between respiratory cells and viral pathogens.

Nontypeable Haemophilus influenzae (NTHI) is an important respiratory pathogen. NTHI initiates infection by adhering to the airway epithelium. Here, we report that NTHI interacts with intracellular adhesion molecule 1 (ICAM-1) expressed by respiratory epithelial cells. A fourfold-higher number of NTHI bacteria adhered to Chinese hamster ovary (CHO) cells transfected with human ICAM-1 (CHO-ICAM-1) than to control CHO cells ( P ≤ 0.005). Blocking cell surface ICAM-1 with specific antibody reduced the adhesion of NTHI to A549 respiratory epithelial cells by 37% ( P = 0.001) and to CHO-ICAM-1 cells by 69% ( P = 0.005). Preincubating the bacteria with recombinant ICAM-1 reduced adhesion by 69% ( P = 0.003). The adherence to CHO-ICAM-1 cells of NTHI strains deficient in the adhesins P5, P2, HMW1/2, and Hap or expressing a truncated lipooligosaccharide was compared to that of parental strains. Only strain 1128f − , which lacks the outer membrane protein (OMP) P5-homologous adhesin (P5 fimbriae), adhered less well than its parental strain. The numbers of NTHI cells adhering to CHO-ICAM-1 cells were reduced by 67% ( P = 0.009) following preincubation with anti-P5 antisera. Furthermore, recombinant ICAM bound to an OMP preparation from strain 1128f + , which expresses P5, but not to that from its P5-deficient mutant, confirming a specific interaction between ICAM-1 and P5 fimbriae. Incubation of respiratory epithelial cells with NTHI increased ICAM-1 expression fourfold ( P = 0.001). Adhesion of NTHI to the respiratory epithelium, therefore, upregulates the expression of its own receptor. Blocking interactions between NTHI P5 fimbriae and ICAM-1 may reduce respiratory colonization by NTHI and limit the frequency and severity of NTHI infection.

Apoptosis of murine and human macrophages induced by group B Streptococcus agalactiae (GBS) is likely an important virulence mechanism that is used by the bacteria to suppress the host immune response and to persist at sites of infection. The mechanisms by which GBS induces apoptosis are, however, largely unknown. In this study, we report that in murine macrophages GBS induces unique changes in the regulation and localization of the apoptotic regulators Bad, 14-3-3, and Omi/high-temperature requirement A2 and leads to the release of cytochrome c and the activation of caspase-9 and caspase-3. Furthermore, inhibition of caspase-3 impaired GBS-induced apoptosis of macrophages. The ability to modulate the activity of effector caspases may therefore represent an unexploited avenue for therapeutic intervention in GBS infections.

Serotype III group B streptococci (GBS) are a common cause of neonatal sepsis and meningitis. Although deficiency in maternal capsular polysaccharide (CPS)-specific IgG correlates with susceptibility of neonates to the GBS infection, serum deficient in CPS-specific IgG mediates significant opsonophagocytosis. This IgG-independent opsonophagocytosis requires activation of the complement pathway, a process requiring the presence of both Ca2+ and Mg2+, and is significantly reduced by chelating Ca2+ with EGTA. In these studies, we defined a role of L-ficolin/mannose-binding lectin-associated serine protease (MASP) complexes in Ca2+-dependent, Ab-independent opsonophagocytosis of serotype III GBS. Incubation of GBS with affinity-purified L-ficolin/MASP complexes and C1q-depleted serum deficient in CPS-specific Ab supported opsonophagocytic killing, and this killing was inhibited by fluid-phase N-acetylglucosamine, the ligand for L-ficolin. Binding of L-ficolin was proportional to the CPS content of individual strains, and opsonophagocytic killing and C4 activation were inhibited by fluid-phase CPS, suggesting that L-ficolin binds to CPS. Sialic acid is known to inhibit alternative complement pathway activation, and, as expected, the bactericidal index (percentage of bacteria killed) for individual strains was inversely proportional to the sialic acid content of the CPS, and L-ficolin-initiated opsonophagocytic killing was significantly increased by addition of CPS-specific IgG2, which increased activation of the alternative pathway. We conclude that binding of L-ficolin/MASP complexes to the CPS generates C3 convertase C4b2a, which deposits C3b on GBS. C3b deposited by this lectin pathway forms alternative pathway C3 convertase C3bBb whose activity is enhanced by CPS-specific IgG2, leading to increased opsonophagocytic killing by further deposition of C3b on the GBS.

In this study, we reviewed cases of invasive disease due to nontypeable Haemophilus influenzae among children hospitalized at Arkansas Children's Hospital from 1993 to 2001. A total of 28 cases were examined, including 21 associated with bacteremia and 4 associated with meningitis. Of the patients examined, 86% were ≤4 years of age, and 68% had underlying medical conditions. Characterization of the bacterial isolates by multilocus sequence type genotyping revealed significant overall genetic diversity, similar to the diversity in the general population structure for nontypeable H. influenzae . However, four separate pairs of isolates were closely related genetically, a relationship confirmed by pulsed-field gel electrophoresis and Southern hybridization studies using probes for the major H. influenzae adhesin genes. These results suggest that selected strains of nontypeable H. influenzae may have more invasive potential, especially in young children and patients with underlying medical conditions. At this point, the specific factors that contribute to enhanced virulence remain unclear.

Human isolates of serotype III Streptococcus agalactiae (group B streptococcus [GBS]) can be divided into three separate phylogenetic lineages based on analysis of the restriction digest patterns (RDPs) of chromosomal DNA. Nine DNA sequences that are present in all isolates of the RDP III-3 phylogenetic lineage, but not in the other lineages, were identified by genomic subtractive hybridization. A complete physical map of a III-3 chromosome was constructed. Six of the nine III-3-specific sequences mapped to a 340-kb Sse 8387I fragment which contains or is located close to known GBS virulence genes. One of the III-3-specific probes, AW-10, encodes part of GBSi1, a group II intron that is inserted at two sites within the GBS genome. The second chromosomal site for GBSi1 was isolated, sequenced, and mapped to a location near the locus responsible for hemolysin production. These findings suggest that the genetic variation that distinguishes the RDP type III-3 strains from other serotype III strains occurs largely within localized areas of the genome containing known or putative virulence genes.

To describe the characteristics of benign and malignant mediastinal masses, which may predict their etiology and facilitate the safe and timely management of patients, especially those residing in histoplasmosis-endemic regions.We conducted a retrospective review of the health records of 131 patients aged19 years who were referred to 2 tertiary care children's hospitals between 2005 and 2010 for evaluation of mediastinal masses.Most patients (79%) had benign masses, including 98 with confirmed or suspected histoplasmosis. Overall, compared with patients with malignant masses, patients with benign masses were younger and more likely to be African American, to complain of cough, and to have pulmonary nodules by chest computed tomography. In addition, patients with malignant disease were more likely to complain of malaise and to have neck swelling, abnormal extrathoracic lymphadenopathy, lymphopenia, anterior mediastinal involvement, and/or pleural effusion. Positive histoplasmosis serologic tests were specific but insensitive for a benign etiology. No single clinical, laboratory, or radiologic feature was sufficiently sensitive and specific for distinguishing between benign and malignant masses; however, the presence of lymphopenia, anterior mediastinal involvement, or enlarged cervical lymph nodes on computed tomography had a sensitivity of 93%, specificity of 95%, positive predictive value of 86%, and negative predictive value of 97% for cancer. Sixty-four patients (49%) underwent invasive testing, including 37 (36%) of those with benign masses.Patients in this series who had involvement of the anterior mediastinum, lymphopenia, or enlarged cervical lymph nodes had a high likelihood of cancer. Expectant management of patients lacking these characteristics may be safe and reduce unnecessary invasive testing.

Background. Rapidly growing mycobacteria (RGM) infections in pediatric oncology patients have not been completely characterized. Methods. We reviewed medical records of oncology patients at St. Jude Children’s Research Hospital (St. Jude) from 1990 to 2010 with RGM infections and summarized the results of previously published cases. Results. Twenty-five St. Jude patients had 27 episodes of infection. Approximately half of the cases occurred in patients with hematological malignancies and in males; infections were more common in white patients. Most patients were not neutropenic or lymphopenic. The most common causative species were Mycobacterium chelonae, Mycobacterium abscessus, and Mycobacterium fortuitum. Most isolates were susceptible to amikacin and clarithromycin; all were susceptible to at least 1 of these. Treatment regimens varied considerably, particularly with respect to the duration of antimicrobial chemotherapy. Two St. Jude patients died; both had pulmonary infections. The literature search identified an additional 58 cases of infection. Localized catheter-associated infections were more common than bloodstream infections in the current series than in previous reports, and outbreaks were not recognized. Otherwise, the demographic and clinical characteristics of patients were similar. Conclusions. Localized catheter-associated infections were most common in this largest reported single center experience reported to date. Pulmonary infection is uncommon in children but, as in adults, has a high mortality rate. Relativelyshort-term antimicrobial treatment and surgical debridement of infected tissue, if present, may be as effective forcatheter-associated infections as prolonged antimicrobial use and may reduce adverse drug effects in these patients, who are vulnerable to drug-drug interactions and toxicity.

Polysaccharide(PS)-encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis are among the most prevalent bacterial pathogens of humans. Infections caused by these organisms are both common (otitis media, sinusitis) and severe (meningitis, bacteremia). Antibodies directed against the capsular PS of encapsulated bacteria prevent infection by promoting opsonophagocytic killing. Most bacterial PS, however, are type II T-cell-independent (TI-2) antigens that are poorly immunogenic in young children at highest risk of developing disease. Conjugation of bacterial PS to a protein carrier converts the immune response to a T-cell-dependent (TD) form and significantly improves the immunogenicity of PS, especially in infants. H. influenzae type b (Hib) is a major cause of invasive infection in non-immune children. The medical importance of this pathogen and the availability of both TI-2 and TD Hib PS vaccine formulations have made the human anti-Hib-PS immune response an excellent model for the study of the biology of these B cell responses.

Previous work divided serotype III group B streptococci (GBS) into 3 major phylogenetic lineages (III-1, III-2, and III-3) on the basis of bacterial DNA restriction digest patterns (RDPs). Most neonatal invasive disease was caused by III-3 strains, which implies that III-3 strains are more virulent than III-2 or III-1 strains. In the current studies, all RDP III-3 and III-1 strains expressed hyaluronate lysase activity; however, all III-2 strains lack hyaluronate lysase activity, because the gene that encodes hyaluronate lysase, hylB, is inactivated by IS1548. Subtractive hybridization was used to identify 9 short DNA sequences that are present in all the III-3 strains but not in any of the III-2 or III-1 strains. With 1 exception, these III-3-specific sequences were not detected in nonserotype III GBS. These data further validate the RDP-based subclassification of GBS and suggest that lineage-specific genes will be identified, which account for the differences in virulence among the lineages.

Nucleotide sequences of VH- and VL-genes of anti-myosin/anti-streptococcal monoclonal antibodies (mAbs) were analyzed and compared with their highly detailed antigen binding reactivities. Antigen-specificities of the cross-reactive mAbs included myosin, streptococcal M-protein, actin, keratin, N-acetyl-beta-D-glucosamine, vimentin, DNA, tropomyosin, troponin, and laminin as previously described. After nucleotide sequence analysis, homology indicated that some of the V gene sequences aligned with antibodies recognizing gangliosides and blood group antigens glycophorin M and N. Therefore, mAb reactivity with gangliosides and glycophorin M and N was identified. The cross-reactive mAbs utilized a heterogeneous group of germline V-heavy genes comprised of nine J558-, four 7183- and two Q52-family VH-genes. Germline V-light genes utilized by the mAbs included six Vkappa4/5-, three Vkappa8-, two Vkappa10-, three Vkappa19- and one Vkappa23-family VL-genes. No preferential VH/VL-chains correlated with any of the 12 different antigen reactivities, even for mAbs with nearly identical cross-reactivities. However, we did find that the cross-reactive mAb germline genes within a V gene family shared more homology among themselves than with other germline genes within their V gene families, suggesting convergent mutation. Cross-reactive mAbs with the highest relative avidity for myosin were found in the VH7183 family which contained two cytotoxic mAbs. Antibodies with V gene sequences most homologous to those of our cross-reactive anti-myosin/anti-streptococcal mAbs had specificities for laminin, DNA, carbohydrates, or blood group antigens and were reported to cause autoimmune disease in mice.

Many group BStreptococcus agalactiaestrains and other pathogenic streptococci express a cell-associated peptidase that inactivates C5a (C5a-ase), the major neutrophil chemoattractant produced by activation of the complement cascade. Type III group B streptococci (GBS) can be classified genotypically into three restriction digest pattern types. Functional C5a-ase activity of GBS correlates with this genetic typing; therefore, we sought to identify a genetic basis for this phenomenon. Southern hybridization confirms that all type III GBS containscpB, the gene encoding GBS C5a-ase. GBS strains with high C5a-ase functional activity and those with no or very low activity both express immunoreactive C5a-ase. ThescpBsequence of strain I30, which has high C5a-ase activity, is 98.2% homologous to the previously reported serotype II GBSscpBsequence. ThescpBsequences of strains I25 and GW, which have low or no C5a-ase activity, are identical. The predicted I25 and GW C5a-ase proteins share a four-amino-acid deletion affecting the protease histidine active-site consensus motif. Recombinant I30 C5a-ase has good functional activity, whereas recombinant I25 C5a-ase has low activity. These data demonstrate that functional C5a-ase differences between type III GBS strains are attributable to a genetic polymorphism ofscpB. The ubiquitous expression of C5a-ase, irrespective of functional activity, suggests that C5a-ase may have a second, as yet unidentified, function.

Serotype III group B Streptococcus agalactiae (GBS) are the most common cause of neonatal sepsis and meningitis. We have classified type III GBS by restriction digest patterns of chromosomal DNA and demonstrated that a subgroup of genetically related strains (RDP type III-3) causes the majority of type III GBS neonatal infection. Genetic differences between type III GBS strains contribute significantly to differences in virulence and host immune responses. While 100% of less virulent RDP type III-1 and III-2 organisms express C5a-ase, an inhibitor of neutrophil chemotaxis, only 63% of virulent RDP type III-3 isolates have functional C5a-ase. Functional differences in type III GBS C5a-ase are attributable to a shared genetic polymorphism, supporting our genetic classification. The mean capsular sialic acid content of virulent RDP type III-3 strains is significantly higher than that of less virulent strains, suggesting that capsular sialylation is also genetically regulated. C5a-ase is not critical for all RDP type III-3 strains to be invasive because the higher capsular sialic acid content of III-3 strains limits complement activation. The identification of these and additional genetic differences between GBS strains has important implications for our understanding of the pathogenesis of these important human infections.

We report on two children who may represent a novel syndrome consisting of a deficiency of immunoglobulin-bearing B lymphocytes and serum antibody, deficient intrauterine and/or postnatal growth, intracranial calcifications, and acquired pancytopenia. Poor growth, intracranial calcifications, developmental delay, and hematological abnormalities are common manifestations of congenital infection. However, humoral immunodeficiency is not characteristic in these infections, and no infection was found on extensive evaluation. Rare genetic syndromes may mimic intrauterine infections and may also include immunodeficiency. However the children reported here lack important characteristics or share distinctive manifestations not described in these disorders. Infants presenting with apparent congenital infections in whom a specific infectious cause cannot be identified should be followed carefully with immunological evaluations since this disorder may be progressive and considerable morbidity is attributable to hematological and immunological manifestations.

Secondary immune responses to T-independent antigens are characterized by little or no affinity maturation, a phenomenon attributed to limited somatic hypermutation. In the human immune response to Haemophilus influenzae type b capsular polysaccharide, however, there are numerous differences between rearranged heavy chain variable region gene segments and candidate germline genes, irrespective of antigen presentation in a T-independent or T-dependent form. To determine the characteristics of somatic hypermutation in this response, we analyzed rearranged heavy chain variable region segments and associated 3' untranslated JH4-JH5 introns from monoclonal anti-Hib PS antibodies. Mutation of untranslated introns and heavy chain variable segments in both T-independent and T-dependent responses resembles that described in murine and unselected human immune responses. Although mutation is frequent in both T-independent and T-dependent anti-Hib PS responses, there is little evidence of antigen-driven selection, suggesting that ongoing pressure to conserve the variable segment germline configuration limits affinity maturation in this immune response.

Conjugation of bacterial polysaccharides (PS) to protein carriers confers the ability to elicit protective serum Ab in infants, who respond poorly to plain PS. The serum Ab of young children immunized with Haemophilus influenzae type b (Hib) PS conjugate vaccine varies with age and Ag formulation. To understand these age-related changes in human anti-Hib PS immune responses we determined the variable region gene sequences encoding anti-Hib PS mAbs of infants immunized with Hib oligosaccharide-diphtheria toxin vaccine. The anti-Hib PS repertoire of children differs from that of adults. A smaller proportion of mAbs from children have high affinity for Hib PS, and the overall variable region gene repertoire of infants is more diverse than that in adults. Variable region genes encoding high affinity mAbs of infants are similar to the restricted repertoire described in adults. Low affinity anti-Hib PS mAbs of infants are encoded by a heterogeneous group of genes that are uncommonly observed in the adult repertoire. Abs with high affinity for Hib PS from infants, like most mAbs from adults, react only with Hib PS and the structurally similar PS of Escherichia coli K100, whereas low affinity mAbs of infants are polyreactive. The low affinity anti-Hib PS mAbs of infants immunized with Hib oligosaccharide-diphtheria toxin vaccine vaccine are not reflected in serum Ab. However, the differences between the variable region gene repertoires of adults and infants may account for the distinct immunologic characteristics of the anti-Hib PS responses in young children immunized with other vaccine formulations.

Purpose: The aim of this study was to define patient characteristics, risk factors, microbiology, and outcome of spontaneous intestinal perforations (SIP) in premature infants. Methods: To identify the characteristics and frequency of SIP, the medical records of 94 premature infants were reviewed retrospectively. Results: Eleven infants experienced 12 episodes of SIP and 53 infants had 55 episodes of confirmed necrotizing enterocolitis (NEC). Compared with infants who had NEC, the infants with SIP were smaller and born more prematurely. The onset of illness was earlier and was associated with antecedent hypotension, leukocytosis, and a gasless appearance on abdominal radiograph. Blue abdominal discoloration was present in 11 of 12 babies with SIP, but in only one of the babies with NEC. Infants with SIP were significantly more likely to have systemic candidiasis. When controlling for birth weight and age, early onset, blue abdomen, and a gasless abdominal radiograph continued to be statistically significant markers of SIP. Conclusions: SIP occurs about 12-fold less frequently than NEC in preterm infants. A combination of clinical, laboratory, and radiological features distinguish very low birthweight infants with SIP from those with NEC. Obvious signs of bowel perforation are infrequent with SIP. SIP is frequently associated with systemic candidiasis.

Anti-myosin Abs are associated with inflammatory heart diseases such as rheumatic carditis and myocarditis. In this study, human cross-reactive anti-streptococcal/anti-myosin mAbs 1.C8, 1.H9, 5.G3, and 3.B6, produced from peripheral blood lymphocytes of patients with rheumatic carditis, and mAb 10.2.5, produced from a tonsil, were characterized, and the nucleotide sequences of their VH and VL genes were analyzed. Human mAbs 1.C8, 1.H9, 10.2.5, and 3.B6 reacted with human cardiac myosin while mAb 5.G3 did not. The mAbs were strongly reactive with N-acetyl-β-d-glucosamine, the dominant epitope of the group A streptococcal carbohydrate. mAb 1.H9 was moderately cytotoxic to rat heart cells in vitro in the presence of complement. The anti-myosin mAbs from rheumatic carditis were found to react with specific peptides from the light meromyosin region of the human cardiac myosin molecule. Anti-streptococcal/anti-myosin mAbs from normal individuals reacted with distinctly different light meromyosin peptides. The mAbs were encoded by VH3 gene segments V3-8, V3-23, and V3-30 and by the VH4 gene segment V4-59. The variable region genes encoding the anti-streptococcal/anti-myosin repertoire were heterogeneous and exhibited little evidence of Ag-driven somatic mutation.

Hematogenous focal infections are a rare complication of bacteremia or sepsis caused by viridans-group streptococci. We describe two patients with acute leukemia who developed myositis during α-hemolytic streptococcal bacteremia. Children complaining of severe muscle pain associated with viridans streptococcal infections should be carefully evaluated for the presence of focal pyogenic complications and rhabdomyolysis. The severity of infectious myositis is highly variable, depending on the etiologic organism and host immunity, making individualized treatment the most effective approach. © 2004 Wiley-Liss, Inc.

Changes in oncology care and the diagnosis and management of influenza over the past several decades may have altered the epidemiology and outcomes of influenza in pediatric oncology patients.The clinical features and outcomes of 102 pediatric patients undergoing cancer therapy during 107 episodes of influenza between January 2002 and April 2009 were retrospectively ascertained.Median age at the time of influenza was 7.2 years (interquartile range: 3.8-11.2 years); 46% of patients were male. Nineteen patients (18%) were recipients of hematopoietic stem cell transplants. Patients' median absolute neutrophil and lymphocyte counts were 1300/μL (interquartile range: 500-2967/μL) and 360/μL (interquartile range: 180-836/μL), respectively. Twelve patients (11%) had coinfections with influenza and one or more other respiratory pathogens. Influenza prompted patients' hospitalization during 64% of episodes, and 75% received antiviral therapy. Complications occurred in 30% of infections and serious complications occurred in 7%. Three patients died, but no deaths were directly attributable to influenza. Most patients had delays in cancer therapy; the median delay was 5 days. Neutropenia, concurrent infection, increasing age and having received hematopoietic stem cell transplant increased the risk of serious complications.Advances in the management of pediatric cancer and influenza have not altered the epidemiology and outcome of influenza in oncology patients. Clinical features identify subgroups of patients with influenza who are at risk of poor outcomes and those with a good prognosis.

Background Concern has been raised about possible increased mortality associated with the use of cefepime. There are limited data available on the pragmatic use of beta-lactam antibiotics, especially in children. Procedure This retrospective study included 532 pediatric oncology patients. The outcomes of patients treated with cefepime for suspected serious bacterial infections were compared to those of patients treated with ceftazidime. Primary outcomes included 30- and 90-day all-cause mortality. Results The demographic and clinical characteristics of 337 patients treated with ceftazidime were similar to those of 195 patients receiving cefepime. Thirty-day and 90-day all cause mortality rates were comparable (30-day OR for cefepime: 3.48, 95% CI 0.31–38.84, P = 0.3; 90-day OR: 0.99, 95% CI 0.29–3.42, P = 1.0). There were also no differences in infection-related mortality rates, secondary infections, or adverse drug events. Deaths occurring within 30 days of hospitalization were judged to be attributable to infection, but not the result of treatment failure or adverse drug events. Deaths occurring between 30 and 90 days were associated with progressive or new malignancy. Secondary infection was significantly associated with mortality. Conclusions The use of cefepime in pediatric oncology patients is not associated with increased mortality when compared to ceftazidime, however the small number of deaths in this study limits the strength of this conclusion. Previous associations between antimicrobial therapy and increased all-cause mortality may have been confounded by patients' demographic characteristics and co-morbid conditions. All-cause mortality may be an insensitive outcome for studies examining the efficacy and safety of these agents. Pediatr Blood Cancer 2013; 60: 806–809. © 2013 Wiley Periodicals, Inc.

Background. The safety and immunogenicity of live, attenuated influenza vaccine (LAIV) has not been compared to that of the standard trivalent inactivated vaccine (TIV) in children with cancer. Methods. Randomized study of LAIV versus TIV in children with cancer, age 2‐21 years, vaccinated according to recommendations based on age and prior vaccination. Data on reactogenicity and other adverse events and blood and nasal swab samples were obtained following vaccination. Results. Fifty-five eligible subjects (mean age, 10.4 years) received vaccine (28 LAIV/27 TIV). Both vaccines were well tolerated. Rhinorrhea reported within 10 days of vaccination was similar in both groups (36% LAIV vs 33% TIV, P . .999). Ten LAIV recipients shed virus; the latest viral shedding was detected 7 days after vaccination. Immunogenicity data were available for 52 subjects, or 26 in each group. TIV induced significantly higher postvaccination geometric mean titers against influenza A viruses (P , .001), greater seroprotection against influenza A/H1N1 (P 5 .01), and greater seroconversion against A/H3N2 (P 5 .004), compared with LAIV. No differences after vaccination were observed against influenza B viruses. Conclusions. As expected, serum antibody response against influenza A strains were greater with TIV than with LAIV in children with cancer. Both vaccines were well tolerated, and prolonged viral shedding after LAIV was not detected.