Varicella associated pneumoniae in a pediatric population.

BACKGROUND: Varicella pneumonia has been studied extensively in adults; it may also affect children and may require hospitalization. METHODS: We examined pneumonia complications in children hospitalized for varicella, over a 13 year period. RESULTS: Pneumonia occurred in 8.2% of children hospitalized for varicella. The median length of hospitalization was 6 days. No statistically significant difference in length of stay was detected between immunodepressed children and previously healthy children. The hospitalization was on average shorter in patients who started antiviral therapy within 24 h of varicella onset. None of the included patients had been previously immunized for varicella. CONCLUSIONS: Our results support the need for increased awareness of current varicella prevention recommendations among both immunocompetent and immunodepressed individuals. In children affected by varicella, prompt antiviral therapy may be indicated to reduce the number of days of hospitalization.

[Vaccination in childhood: how to protect the "unprotectable"?] / Le vaccinazioni dell'infanzia: proteggere gli "improteggibili".

The failure of immunization coverage is the primary reason for the transmission and the spread of the diseases in young infants not eligible for vaccination because of age and in immunocompromised individuals. In both these categories measles, pertussis and varicella could be devastating. Pertussis, measles and varicella in the first year of life are responsible to the ED admission, the hospitalization and, exceptionally, the death. The only way to protect very young infants and immunocompromised individuals is to obtain the adequate coverage in all the population.

Human B-cell memory is shaped by age- and tissue-specific T-independent and GC-dependent events.

Switched and IgM memory B cells execute different and noninterchangeable functions. We studied memory B cells in children of different ages, in peripheral blood and spleen and compared them with those of children born asplenic or unable to build germinal centers. We show that, whereas switched memory B cells are mostly generated in the germinal centers at all ages, IgM memory B cells can be distinct in three types with different developmental history. Innate IgM memory B cells, the largest pool in infants, are generated in the spleen by a germinal center-independent mechanism. With age, if the spleen is present and germinal centers are functional, innate IgM memory B cells are remodelled and accumulate somatic mutations. The third type of IgM memory B cell is a by-product of the germinal center reaction. Our data suggest that the B-cell memory developmental program is implemented during the first 5-6 years of life.

Repeated vaccinations do not improve specific immune defenses against Hepatitis B in non-responder health care workers.

Hepatitis B is a major infectious occupational hazard for health care workers and can be prevented with a safe and effective vaccine. The serum titer of anti-HBsAg antibodies is the most commonly used correlate of protection and post-vaccination anti-HBsAg concentrations of ≥ 10 mIU/ml are considered protective. Subjects with post-vaccination anti-HBsAg titers of <10 mIU/ml 1-6 months post-vaccination, who tested negative for HBsAg and anti-HBc, are defined as non-responders. The question of whether non-responders should be repeatedly vaccinated is still open. The aim of the study was to (i) evaluate the distribution of lymphocyte subpopulations and the percentage of HBsAg-specific memory B cells in responders and non-responders (ii) assess whether non-responders can be induced to produce antibodies after administration of a booster dose of vaccine (iii) determine whether booster vaccination increases the number of specific memory B cells in non-responders. Combining flow-cytometry, ELISPOT and serology we tested the integrity and function of the immune system in 24 health care workers, confirmed to be non-responders after at least three vaccine injections. We compared the results with those obtained in 21 responders working in the same institution. We found that the great majority of the non-responders had a functional immune system and a preserved ability to respond to other conventional antigens. Our most important findings are that the frequency of HBsAg-specific memory B cells is comparable in non-responders and controls and that booster immunization does not lead either to antibody production or memory B cell increase in non-responders.

Vaccine risk assessment in children with a referred reaction to a previous vaccine dose: 2009-2011 retrospective report at the Bambino Gesu' children hospital, Rome, Italy.

BACKGROUND: During the last century, mass vaccination programs have achieved considerable success across the world in immunizing against several serious infectious diseases. However, vaccinations are threatened by their own success after results have been obtained: the more the incidence of potentially devastating diseases decreases, thanks to the success of vaccination programs, the more public attention shifts towards real or alleged "side effects" of vaccines. METHODS: We analyze the experience of 153 children with "reaction to a previous vaccine dose" continuing the vaccination protocol in the safe environment of the Center for risk vaccination at the Bambino Gesù Children's Hospital IRCCS in Rome, from 2009 to 2011. RESULTS: To assess the suitability for vaccination, a specialized pre-vaccination advice and a skin prick test (SPT) was undergone, according to Wood's guideline; 151 children were SPT negative and full vaccine was administered. Of the 153 children examined just 13 had symptoms suggestive of IgE-mediated reaction-type reactions with angioedema manifestations. Among them, 2 had positive STP, which required alternative measures of administration of the vaccine. No cases of post vaccination reaction was reported and no vaccination program was stopped due to a severe reaction. CONCLUSIONS: Inadequate levels of immunization against infectious diseases remain a significant problem for public health. However, the reasons for incomplete vaccination and non-adoption of vaccination services are manifold. To maintain public confidence in vaccines, advanced immunization programs must include activities for monitoring the safety of the vaccine at the individual level and pursuing specialized counseling pre-and post-vaccination for those at risk. Our results underlined a gap between true and referred adverse reactions and are consistent with vaccine safety. Anyway, a continuous assessment of the risks and benefits of vaccination is required and the results must be disclosed in order to strengthen confidence in the existing and in the new immunization programs.

Preserved antibody levels and loss of memory B cells against pneumococcus and tetanus after splenectomy: tailoring better vaccination strategies.

Splenectomized patients are exposed to an increased risk of septicemia caused by encapsulated bacteria. Defense against infection is ensured by preformed serum antibodies produced by long-lived plasma cells and by memory B cells that secrete immunoglobulin in response to specific antigenic stimuli. Studying a group of asplenic individuals (57 adults and 21 children) without additional immunologic defects, we found that spleen removal does not alter serum anti-pneumococcal polysaccharide (PnPS) IgG concentration, but reduces the number of PnPS-specific memory B cells, of both IgM and IgG isotypes. The number of specific memory B cells was low in splenectomized adults and children that had received the PnPS vaccine either before or after splenectomy. Seven children were given the 13-valent pneumococcal conjugated vaccine after splenectomy. In this group, the number of PnPS-specific IgG memory B cells was similar to that of eusplenic children, suggesting that pneumococcal conjugated vaccine administered after splenectomy is able to restore the pool of anti-PnPS IgG memory B cells. Our data further elucidate the crucial role of the spleen in the immunological response to infections caused by encapsulated bacteria and suggest that glycoconjugated vaccines may be the most suitable choice to generate IgG-mediated protection in these patients.

Immune reconstitution and vaccination outcome in HIV-1 infected children: present knowledge and future directions.

Current evidence on routine immunization of HIV-1 infected children point out the need for a special vaccine schedule in this population. However, optimal strategies for identifying individuals susceptible to infections, and then offering them sustained protection through appropriate immunization schedule, both in terms of timing and number of vaccine doses, still remain to be elucidated. Understanding the degree of immune recovery after HAART initiation is important in guiding administration of routine vaccination in HIV-1 infected children. Although quantitative measures (e.g., CD4+ T-cell counts and immunoglobulin levels) are frequently performed to evaluate immune parameters, these measures do not fully mirror functional immune recovery. Here, we will review the status of single mandatory and recommended vaccines for HIV-1 infected children in relation to immune recovery after HAART initiation with the aim of identifying new means to help design personalized vaccine schedules for this population.

[Streptococcus pneumoniae meningitis in children. Case records 1985 - 2003]. / Meningite da Streptococcus pneumoniae in età pediatrica. Considerazioni su una casistica 1985 - 2003.

Acute bacterial meningitis and sepsis are the most severe among invasive diseases due to Streptococcus pneumoniae, particularly in pediatric age, and present a high risk of mortality and neurologic sequelae. S. pneumoniae is a major worldwide pathogen in children. The widespread emergence of penicillin-resistant pneumococci, a new pneumococcal conjugate vaccine, and the epidemiological prevalence of some serotypes, have recently focused attention on S. pneumoniae disease. We reviewed the data on incidence, epidemiology, diagnosis, therapy in children hospitalized with acute bacterial meningitis in the Division of Infectious Diseases of the Bambino Gesu Children's Hospital, Rome, between 1985- 2003. S. pneumoniae was isolated in 16.3% of the children, progressively emerging as the prevalent pathogen. The highest incidence was found in children younger than 2 yrs. The disease still presents a high rate of long-term sequelae, especially hearing loss and neurological handicap. Penicillin and ampicillin resistant isolates were found in 2.3% of positive cultures; no strain was resistant to cephalosporins and vancomycin. Our data support the recommendations to consider administration of the 7-valent pneumococcal conjugate vaccine for children older than 2 months of age, with special consideration for selected groups. We recommend monitoring all invasive pneumococcal infections in children, the emergence of antibiotic-resistance and changes in prevalence of pathogen serotypes.

[Mediastinal tubercular lymphadenitis and adenobronchial fistulas (TABF) in the paediatric age. 1980-2001 case record]. / Linfoadeniti mediastiniche e fistole adeno-bronchiali tubercolari (FABT) in eta pediatrica. Casistica 1980-2001.

The aim of this study is to assess the frequency and clinical importance of mediastinal tubercular lymphadenitis and adenobronchial fistulas (TABF) and to evaluate the role of fiberbronchoscopy and surgical bronchoscopy associated with antimicrobical chemotherapy. 136 cases of primary pulmonary TBC, admitted to the Unit of Infectious Diseases, Bambino Gesu Children Hospital in Rome, between 1980 and 2001, were enrolled in the study. We considered 56 patients with clinical and radiological evidence of mediastinal tubercular lymphadenitis and 28 patients with adenobronchial fistulas (TABF). The incidence of TABF was 20,58% of primary pulmonary TBC. All patients were treated by medical therapy combined with local endobronchial surgery. TABF emerges as a complication of pediatric primary pulmonary TBC. We suggest a clinical and radiological survey to decide the utility of a diagnostic and therapeutic surgical bronchoscopy