Etiology of community-acquired pneumonia in hospitalized children based on WHO clinical guidelines

Rapport de synthèse: Enjeux de la recherche : La pneumonie communautaire chez l'enfant est un problème de santé publique considérable. Elle est responsable de 2 millions de mort par année, 70% survenant dans les pays en voie de développement. Sous nos latitudes son incidence est de 40/1000 enfants par année, ce qui représente une morbidité importante. Deux difficultés surviennent lorsqu'on cherche à diagnostiquer une pneumonie. La première est de distinguer une pneumonie bactérienne d'une virale, particulièrement chez les petits enfants où les infections virales des voies respiratoires inférieures sont fréquentes. L'OMS a définit la pneumonie selon des critères exclusivement cliniques et une étude effectuée à Lausanne en 2000 a montré que ces critères peuvent être utilisés dans nos contrées. La seconde difficulté est de définir l'agent causal de la pneumonie, ceci pour plusieurs raisons : L'aspiration endotrachéale, seul examen fiable, ne peut être obtenue de routine chez l'enfant vu son caractère invasif, la culture des secrétions nasopharyngées reflète la flore physiologique de la sphère ORL et une bactériémie n'est présente que dans moins de 10% des pneumonies. L'étiologie de la pneumonie reste souvent inconnue, et de ce fait plusieurs enfants reçoivent des antibiotiques pour une infection non bactérienne ce qui contribue au développement de résistances. L'objectif de cette étude était d'effectuer une recherche extensive de l'agent causal de la pneumonie et de déterminer quels facteurs pourraient aider le clinicien à différencier une pneumonie virale de bactérienne, en corrélant l'étiologie avec la sévérité clinique et les marqueurs de l'inflammation. Contexte de la recherche : II s'agissait d'une étude prospective, multicentrique, incluant les enfants âgés de 2 mois à 5 ans hospitalisés pour une pneumonie, selon les critères de l'OMS, dans le service de pédiatrie de Lausanne et Genève entre mars 2003 et Décembre 2005, avant l'implantation de la vaccination antipneumococcique de routine. Chaque enfant, en plus des examens usuels, bénéficiait d'une recherche étiologique extensive : Culture virale et bactérienne, PCR (Mycoplasma Pneumoniae, Chlamydia Pneumoniae, Virus Influenza A et B, RSV A et B, Rhinovirus, Parainfluenza 1-3, enterovirus, human metapneumovirus, coronavirus OC43, E229 ; et NL 63) et détection d'AG viraux dans les sécrétions nasopharyngées ; sérologies virales et bactériennes à l'entrée et 3 semaines après la sortie (AG Influenza A et B, Parainfluenza 1,2 et 3, RSV, Adenovirus, M.Pneumoniae et S.Pneumoniae). Conclusions : Un agent pathogène a été découvert chez 86% des 99 patients retenus confirmant le fait que plus la recherche étiologique est étendue plus le pourcentage d'agent causal trouvé est élevé. Une infection bactérienne a été découverte chez 53% des patients dont 45% avaient une infection à S. Pneumoniae confirmant l'importance d'une vaccination antipneumococcique de routine. La déshydratation et les marqueurs de l'inflammation tels que la C-Reactive Protein et la Procalcitonine étaient significativement plus élevés dans les pneumonies bactériennes. Aucune corrélation n'a été trouvée entre le degré de sévérité de la pneumonie et l'étiologie. L'étude a confirmé la haute prévalence d'infections virales (67%) et de co-infection (33%) dans la pneumonie de l'enfant sans que l'on connaisse le rôle réel du virus dans la pathogenèse de la pneumonie. Perspectives : d'autres études à la suite de celle-ci devraient être effectuées en incluant les patients ambulatoires afin de déterminer, avec un collectif plus large de patient, une éventuelle corrélation entre sévérité clinique et étiologie. Abstract : Community-acquired pneumonia (CAP) is a major cause of death in developing countries and of morbidity in developed countries. The objective of the study was to define the causative agents among children hospitalized for CAP defined by WHO guidelines and to correlate etiology with clinical severity and surrogate markers. Investigations included an extensive etiological workup. A potential causative agent was detected in 86% of the 99 enrolled patients, with evidence of bacterial (53%), viral (67%), and mixed (33%) infections. Streptococcus pneumoniae was accounted for in 46% of CAP. Dehydration was the only clinical sign associated with bacterial pneumonia. CRP and PCT were significantly higher in bacterial infections. Increasing the number of diagnostic tests identifies potential causes of CAP in up to 86% of children, indicating a high prevalence of viruses and frequent co-infections. The high proportion of pneumococcal infections re-emphasizes the importance of pneumococcal immunization.

Antiretroviral treatment of adult HIV infection: 2012 recommendations of the International Antiviral Society-USA panel.

CONTEXT: New trial data and drug regimens that have become available in the last 2 years warrant an update to guidelines for antiretroviral therapy (ART) in human immunodeficiency virus (HIV)-infected adults in resource-rich settings. OBJECTIVE: To provide current recommendations for the treatment of adult HIV infection with ART and use of laboratory-monitoring tools. Guidelines include when to start therapy and with what drugs, monitoring for response and toxic effects, special considerations in therapy, and managing antiretroviral failure. DATA SOURCES, STUDY SELECTION, AND DATA EXTRACTION: Data that had been published or presented in abstract form at scientific conferences in the past 2 years were systematically searched and reviewed by an International Antiviral Society-USA panel. The panel reviewed available evidence and formed recommendations by full panel consensus. DATA SYNTHESIS: Treatment is recommended for all adults with HIV infection; the strength of the recommendation and the quality of the evidence increase with decreasing CD4 cell count and the presence of certain concurrent conditions. Recommended initial regimens include 2 nucleoside reverse transcriptase inhibitors (tenofovir/emtricitabine or abacavir/lamivudine) plus a nonnucleoside reverse transcriptase inhibitor (efavirenz), a ritonavir-boosted protease inhibitor (atazanavir or darunavir), or an integrase strand transfer inhibitor (raltegravir). Alternatives in each class are recommended for patients with or at risk of certain concurrent conditions. CD4 cell count and HIV-1 RNA level should be monitored, as should engagement in care, ART adherence, HIV drug resistance, and quality-of-care indicators. Reasons for regimen switching include virologic, immunologic, or clinical failure and drug toxicity or intolerance. Confirmed treatment failure should be addressed promptly and multiple factors considered. CONCLUSION: New recommendations for HIV patient care include offering ART to all patients regardless of CD4 cell count, changes in therapeutic options, and modifications in the timing and choice of ART in the setting of opportunistic illnesses such as cryptococcal disease and tuberculosis.

Ultrastructural study on experimental infection of rotavirus in a murine heterologous model

Viral replication, histopathological and ultrastructural changes were observed for a period of nine days in the small intestine of suckling mice infected with a simian rotavirus (SA11). Samples taken from duodenum, jejunun and ileum were prepared for light microscopy, transmission and scanning electron microscopy analysis. Histopathologic effect could be detected within 8 hr post-infection, when only a few altered cells were observed. Damage was extensive after 16 hr post-infection, showing swollen enterocytes and reduced and irregularly oriented microvilli at intestinal villi tips. Virus particles were detected at 16 and 48 hr post-infection, budding from the viroplasm into the rough endoplasmic reticulum cisternae in ileum enterocytes. Clear evidence of viral replication, observed by electron microscopy was not described before in heterologous murine models. Regeneration of the intestinal villi began at the third day post-infection. Despite some differences observed in clinical symptoms and microscopic analysis of homologous and heterologous rotavirus infections, we concluded that mechanisms of heterologous rotavirus infection in mice follow similar patterns to those observed in the homologous models.

New and emerging treatment of Staphylococcus aureus infections in the hospital setting.

Methicillin-resistant Staphylococcus aureus (MRSA), both hospital-acquired and community-acquired, is a dangerous pathogen that is involved in an increasing number of serious infections with high risk for morbidity and mortality. Community-acquired MRSA strains have epidemic potential and can be particularly virulent. Vancomycin has been the standard hospital treatment for the past 40 years, but vancomycin-resistant isolates of S. aureus have emerged in the USA, and vancomycin-intermediate isolates are increasingly being reported worldwide. New antimicrobial agents with activity against multidrug-resistant S. aureus and other resistant pathogens are urgently needed. Despite great strides, further advances in our understanding of the molecular and biochemical mechanisms responsible for antimicrobial resistance are still required. Several agents have been recently approved for the treatment of serious Gram-positive infections, including linezolid, daptomycin, and tigecycline. The novel investigational cephalosporin, ceftobiprole, is one of the first penicillinase-resistant agents to target penicillin-binding protein 2a (or PBP2a), an acquired PBP with low beta-lactam-affinity that confers intrinsic beta-lactam resistance to S. aureus and other staphylococci. This mechanism of PBP binding, including inhibition of PBP2a, confers broad-spectrum activity against clinically important Gram-negative and Gram-positive pathogens, including MRSA. Phase III clinical trials comparing ceftobiprole with vancomycin alone and in combination with ceftazidime for the treatment of complicated skin and skin structure infections showed ceftobiprole to have efficacy similar to the efficacy of these comparators as evidenced by non-inferior clinical cure and microbiological eradication rates.

Immuno-epidemiology of Schistosoma mansoni infections in a recently exposed community in Senegal

The levels of IgE and IgG4 increased strongly between cohorts, indicating a dynamic immunological situation, but no immediate impact on infection levels. Morbidity was little specific abdominal discomfort was reported by 61%, diarrhoea by 33% of the subjects; mild hepatomegaly was found in 16%, splenomegaly in 0.5%. No relation to egg counts was observed for any symptom. This mild morbidity may be due to the recent nature of the focus. In the first cohort, the percentage of people with negative egg counts ten weeks after treatment was only 18%, though egg counts declined strongly. Antigen detection confirmed these results. Praziquantel treatment provoked transient but impressive side effects (colics, vomiting, urticaria, aedema), the occurrence of which correlated with intensity of infection. Cure rates in subsequent cohorts were followed up shorter after treatment but remained low. Reinfection nevertheless oppears limited. This lower drug efficacy may be due to very rapid reinfection and/or to the lack of immunity in the population, but also reduced susceptibility of the local parasite strain must be considered and studied.

Acute respiratory infections in children living in two low income communities of Rio de Janeiro, Brazil

Community studies of non-hospitalized children are essential to obtain a more thorough understanding of acute respiratory infections (ARI) and provide important information for public health authorities. This study identified a total ARI incidence rate (IR) of 4.5 per 100 child-weeks at risk and 0.78 for lower respiratory tract infections (LRI). Disease duration averaged less than one week and produced a total time ill with ARI of 5.8% and for LRI 1.2%. No clear seasonal variation was observed, the sex-specific IR showed a higher proportion of boys becoming ill with ARI and LRI and the peak age-specific IR occurred in infants of 6-11 months. Correlation with risk factors of the child (breastfeeding, vaccination, diarrheal disease, undernourishment) and the environment (crowding, living conditions, maternal age and education) showed marginal increases in the rate ratios, making it difficult to propose clear-cuts targets for action to lower the ARI and LRI morbidity. The importance of an integral maternal-child health care program and public education in the early recognition of LRI is discussed.

Respiratory viruses in lung transplant recipients: a critical review and pooled analysis of clinical studies.

Lung transplant recipients present an increased risk for severe complications associated with respiratory infections. We conducted a review of the literature examining the clinical relationship between viral respiratory infection and graft complications. Thirty-four studies describing the clinical impact of influenza, respiratory syncytial virus, parainfluenza, human metapneumovirus, rhinovirus, enterovirus, coronavirus, bocavirus or adenovirus were identified. The detection rate of respiratory viral infection ranged from 1.4% to 60%. Viruses were detected five times more frequently when respiratory symptoms were present [odds ratio (OR) = 4.97; 95% CI = 2.11-11.68]. Based on available observations, we could not observe an association between respiratory viral infection and acute rejection (OR = 1.35; 95% CI = 0.41-4.43). We found a pooled incidence of 18% (9/50) of bronchiolitis obliterans syndrome (BOS) in virus-positive cases compared to 11.6% (37/319) in virus-negative cases; however, limited number of BOS events did not allow to confirm the association. Our review confirms a causal relationship between respiratory viruses and respiratory symptoms, but cannot confirm a link between respiratory viruses and acute lung rejection. This is related in part to the heterogeneity and limitations of available studies. The link with BOS needs also to be reassessed in appropriate prospective studies.

Individual contributions of mutant protease and reverse transcriptase to viral infectivity, replication, and protein maturation of antiretroviral drug-resistant human immunodeficiency virus type 1.

Human immunodeficiency virus type 1 (HIV-1) variants resistant to protease (PR) and reverse transcriptase (RT) inhibitors may display impaired infectivity and replication capacity. The individual contributions of mutated HIV-1 PR and RT to infectivity, replication, RT activity, and protein maturation (herein referred to as "fitness") in recombinant viruses were investigated by separately cloning PR, RT, and PR-RT cassettes from drug-resistant mutant viral isolates into the wild-type NL4-3 background. Both mutant PR and RT contributed to measurable deficits in fitness of viral constructs. In peripheral blood mononuclear cells, replication rates (means +/- standard deviations) of RT recombinants were 72.5% +/- 27.3% and replication rates of PR recombinants were 60.5% +/- 33.6% of the rates of NL4-3. PR mutant deficits were enhanced in CEM T cells, with relative replication rates of PR recombinants decreasing to 15.8% +/- 23.5% of NL4-3 replication rates. Cloning of the cognate RT improved fitness of some PR mutant clones. For a multidrug-resistant virus transmitted through sexual contact, RT constructs displayed a marked infectivity and replication deficit and diminished packaging of Pol proteins (RT content in virions diminished by 56.3% +/- 10.7%, and integrase content diminished by 23.3% +/- 18.4%), a novel mechanism for a decreased-fitness phenotype. Despite the identified impairment of recombinant clones, fitness of two of the three drug-resistant isolates was comparable to that of wild-type, susceptible viruses, suggestive of extensive compensation by genomic regions away from PR and RT. Only limited reversion of mutated positions to wild-type amino acids was observed for the native isolates over 100 viral replication cycles in the absence of drug selective pressure. These data underscore the complex relationship between PR and RT adaptive changes and viral evolution in antiretroviral drug-resistant HIV-1.

The NLRP3 inflammasome in health and disease: the good, the bad and the ugly.

While interleukin (IL)-1β plays an important role in combating the invading pathogen as part of the innate immune response, its dysregulation is responsible for a number of autoinflammatory disorders. Large IL-1β activating platforms, known as inflammasomes, can assemble in response to the detection of endogenous host and pathogen-associated danger molecules. Formation of these protein complexes results in the autocatalysis and activation of caspase-1, which processes precursor IL-1β into its secreted biologically active form. Inflammasome and IL-1β activity is required to efficiently control viral, bacterial and fungal pathogen infections. Conversely, excess IL-1β activity contributes to human disease, and its inhibition has proved therapeutically beneficial in the treatment of a spectrum of serious, yet relatively rare, heritable inflammasomopathies. Recently, inflammasome function has been implicated in more common human conditions, such as gout, type II diabetes and cancer. This raises the possibility that anti-IL-1 therapeutics may have broader applications than anticipated previously, and may be utilized across diverse disease states that are linked insidiously through unwanted or heightened inflammasome activity.

Laboratory indicators for monitoring HIV disease

Immunological monitoring of disease progression following HIV infection and seroconversion illness, latency and AIDS, not only helps in the basic investigation of the natural history of the viral infection in man, but also can assist in prognosis and treatment of AIDS-defining illnesses. However, outside clinical trials, these tests should be selected and used in clinical practice only if they are validated as relevant and effective. The absolute CD4+ T-helper lymphocyte count, measured by flow cytometry, has emerged as the best available investigation, but needs care in sampling due to diurnal and circadian rhythms, effects of age, pregnancy, therapy, intercurrent infections and technique. Sampling should provide a baseline and trends - monthly intervals initially, then quarterly in uncomplicated cases. Thresholds may be given for counts (e.g. 200/µl) below which prophylaxis against pneumocystis pneumonia should be administered, and repeating persistently low counts (e.g. below 50/µl) is seldom helpful in practice. Serum levels of beta-2 microglobulin, neopterin and immunoglobulins rarely add information. Physicians and laboratories should have testing guidelines based on clinical audit of best practice, based in turn on scientific understanding of the immunological processes involved.

Trypanosoma cruzi in the anal glands of urban opossums: I- isolation and experimental infections

Opossums (Didelphis marsupialis) captured in intensely urbanized areas of the city of Caracas, Venezuela, were found infected with Trypanosoma cruzi. The developmental cycle of trypomastigote-epimastigote-metacyclic infective trypomastigote, usually occurring in the intestine of the triatomine vector, was taking place in the anal odoriferous glands of the opossums. Material from the glands, inoculated in young, healthy opossums and white mice by different routes, subcutaneously, intraperitoneally, orally, and into the eye, induced T. cruzi infections in all animals. Parasitemia, invasion of cardiac and skeletal muscle, and intracellular multiplication of amastigotes were observed. Inoculation of metacyclics from anal glands, cultured in LIT medium, gave equivalent results. All opossums survived; all mice died. Excreta of opossums may thus transmit Chagas' disease by contamination, even in urban areas where insect vectors are not present.

Histopathological study of experimental and natural infections by Trypanosoma cruzi in Didelphis marsupialis

Didelphis marsupialis, the most important sylvatic reservoir of Trypanosoma cruzi, can also maintain in their anal scent glands the multiplicative forms only described in the intestinal tract of triatomine bugs. A study of 21 experimentally and 10 naturally infected opossums with T. cruzi was undertaken in order to establish the histopathological pattern under different conditions. Our results showed that the inflammation was predominantly lymphomacrophagic and more severe in the naturally infected animals but never as intense as those described in Chagas' disease or in other animal models. The parasitism in both groups was always mild with very scarce amastigote nests in the tissues. In the experimentally infected animals, the inflammation was directly related to the presence of amastigotes nests. Four 24 days-old animals, still in embryonic stage, showed multiple amastigotes nests and moderate inflammatory reactions, but even so they survived longer and presented less severe lesions than experimentally infected adult mice. Parasites were found in smooth, cardiac and/or predominantly striated muscles, as well as in nerve cells. Differing from the experimentally infected opossums parasitism in the naturally infected animals predominated in the heart, esophagus and stomach. Parasitism of the scent glands did not affect the histopathological pattern observed in extraglandular tissues.