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Query: UMLS:C0004623 (bacterial infection)
 15,226 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Haemophilus influenzae in the nasopharynx is thought to be related to the pathogenesis of otitis media with effusion (OME). However, the positive rate measured by the conventional culture method is not high enough for bacterial infection to be considered the chief pathogenic factor. Polymerase chain reaction (PRC) and the conventional culture method were applied to detect H. influenzae in the adenoids and nasopharyngeal secretions of 17 children with OME (2 to 7 years of age). The percentage of P6-positive adenoid samples was 82.4% while 70.6% were culture positive. In nasopharyngeal secretions, 88.2% were P6-positive and 64.7% were culture positive. All samples in which H. influenzae was cultured were positive with PCR. The positive rate was significantly greater with PCR than with the culture method, and it showed a significant concordance between adenoids and nasopharyngeal secretions (p = 0.0027). These findings suggest that the presence of H. influenzae in the nasopharynx is more common in children with OME than previously reported, and that H. influenzae in adenoids might play an important role in OME.
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PMID:Detection of Haemophilus influenzae in adenoids and nasopharyngeal secretions by polymerase chain reaction. 908 63

Three manifestations of pneumonia that are associated with influenza are well recognized: primary influenza viral pneumonia, secondary bacterial pneumonia and mixed viral and bacterial pneumonias. In an outbreak of influenza, primary influenza viral pneumonia has occurred predominantly. After a typical onset of influenza, there is a rapid progression of fever, cough and dyspnea. Physical examination and chest roentgenography reveal bilateral findings but no consolidation. A Gram stain of the sputum fails to reveal significant bacteria, and bacterial culture yield sparse growth of normal flora, where as viral cultures yield high titers of influenza virus. Such patients do not respond to antibiotics. Secondary bacterial pneumonia often produces a syndrome that is clinically distinguishable from that of primary viral pneumonia. Recrudescence of fever is associated with symptoms and signs of bacterial pneumonia such as cough, sputum production, and an area of consolidation detected on physical examination and chest roentgenography. Gram staining and the culture of sputum reveals a predominance of a bacterial pathogen, most often H. influenzae, S. pneumoniae, B. catarrhalis, or S. aureus. Such patients usually respond to specific antibiotic therapy. During an outbreak of influenza many cases an observed that do not clearly fit into either of the aforementioned categories. The disease is not relentlessly progressive, and yet the fever pattern may not be biphasic. These patients may have primary viral, secondary bacterial, or mixed viral and bacterial infection of the lung.
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PMID:[Comparative features of pneumonia associated with influenza]. 936 Mar 92

Macrolides have properties other than their antibiotic action which may benefit patients with airway infections. We have investigated the effect of dirithromycin (0.125 to 8.0 microg/ml) on the interaction of Haemophilus influenzae with respiratory mucosa in vitro using human nasal epithelium, adenoid tissue, and bovine trachea. Dirithromycin did not affect the ciliary beat frequency of the nasal epithelium or the transport of mucus on bovine trachea, but dirithromycin (1 microg/ml) did reduce the slowing of the ciliary beat frequency and the damage to the nasal epithelium caused by H. influenzae broth culture filtrate. Amoxicillin (2 microg/ml) did not reduce the effects of the H. influenzae broth culture filtrate. H. influenzae infection of the organ cultures for 24 h caused mucosal damage and the loss of ciliated cells. Bacteria adhered to damaged epithelium and to a lesser extent to mucus and unciliated cells. Incubation of H. influenzae with dirithromycin at sub-MICs (0.125 and 0.5 microg/ml) prior to infection of the organ cultures did not reduce the mucosal damage caused by bacterial infection. By contrast, incubation of adenoid tissue with dirithromycin (0.125 to 1.0 microg/ml) for 4 h prior to assembling the organ culture reduced the mucosal damage caused by subsequent H. influenzae infection by as much as 50%. The number of bacteria adherent to the mucosa was reduced, although the tissue that had been incubated with dirithromycin (0.125 and 0.5 microg/ml) did not inhibit bacterial growth. This was achieved by a reduction in the amount of damaged epithelium to which H. influenzae adhered and a reduction in the density of bacteria adhering to mucus. We conclude that dirithromycin at concentrations achievable in vivo markedly reduces the mucosal damage caused by H. influenzae infection due to a cytoprotective effect.
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PMID:Effect of dirithromycin on Haemophilus influenzae infection of the respiratory mucosa. 955 81

Haemophilus influenzae is an important respiratory tract pathogen. Toward understanding the progression of H. influenzae from commensal to pathogen, we need to understand the steps of colonization and infection, processes which must involve overcoming the normal host mucociliary clearance mechanism. A reliable method for the screening and quantitation of mucin-H. influenzae binding to allow for the assessment of the physiological variables significant to H. influenzae-mucin interactions in the normal and diseased conditions, will provide insight on how to intervene to prevent, inhibit, or treat infection. The current methods for enumeration of mucin-bound H. influenzae are labor intensive and rely on viable organisms. In this report, we present a new detection method, which reduces the number of variables, processing steps, and time involved, providing an economical, rapid, and reliable means to screen for and quantitate mucin-bound H. influenzae. Organisms are applied to mucin-coated microtiter wells for a set time; nonadherent organisms are removed with gentle rinses; wells are incubated with the phosphomonoesterase substrate p-nitrophenyl phosphate; and the absorbance, reflecting phosphatase activity of the mucin-bound organisms, is read at 410 nm in a microtiter plate reader against enzymatic activity calibration curves. All nonencapsulated and encapsulated H. influenzae tested exhibited significant acid phosphate activity within 20 min, which provided linear relationships with the numbers of organisms present. H. influenzae mucin binding characteristics obtained by this method were generally comparable to published data, and ranged from 10(3) to 10(6) organisms per well, depending on both strain of organism and type of mucin employed. This convenient, rapid and economical mucin adherence assay, will enable more extensive and comprehensive studies of the interactions of H. influenzae adhesins and specific ligands on mucin macromolecules, as well as the nonspecific means by which mucins function in preventing bacterial infection.
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PMID:Acid phosphatase activity as a measure of Haemophilus influenzae adherence to mucin. 1057 7

The aims of this retrospective study were to (i) determine the risk of contamination of lower respiratory tract samples obtained during fiberoscopy in children; (ii) determine the incidence and profile of the bacterial flora of the lower respiratory tract in a selected group of asthmatic children at high risk for bacterial infection; and (iii) identify risk markers for such findings. In 29 asthmatic children, comparison of bacterial cultures of specimens obtained from the upper and, lower respiratory tracts showed that contamination was a possibility in only 3.4% (1/29) of cases. The results from bacterial samples obtained via flexible bronchoscopy in a further 273 consecutively investigated physician-diagnosed asthmatic children were analysed. Patients were selected for bronchoscopy if they had severe chronic asthma or in order to exclude other diseases able to provoke wheezing. Their mean (SD) and median ages were 32.2 (38.3) and 17.5 mo, respectively. The incidence of positive bacterial cultures was 12.1% (33/273 patients). Bacterial flora included H. influenzae (39.5%, 15/38), B. catarrhalis (23.7%, 9/38), Neisseria species (7.9%, 3/38), M. pneumoniae (7.9%, 3/38), P. non-aeruginosa (5.3%, 2/38) and P. aeruginosa (2.6%, 1/38). No clinical or radiological markers were significantly associated with lower respiratory tract bacterial infection. Large quantities of bacteria were present in the lower respiratory tracts of a substantial number of children (1/8) in this selected group of asthmatics. For the moment, however, the clinical implications of this finding remain unclear.
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PMID:Bacterial flora of the lower respiratory tract in children with bronchial asthma. 1059 22

Epithelial cells interact directly with bacteria in the environment and play a critical role in airway defense against microbial pathogens. In this study, we examined the response of respiratory epithelial cells to infection with nontypable Haemophilus influenzae. Using an in vitro cell culture model, we found that epithelial cell monolayers released significant quantities of IL-8 and expressed increased levels of ICAM-1 mRNA and surface protein in response to H. influenzae. In contrast, levels of IL-1beta, TNF-alpha, and MHC class I were not significantly affected, suggesting preferential activation of a specific subset of epithelial genes directed toward defense against bacteria. Induction of ICAM-1 required direct bacterial interaction with the epithelial cell surface and was not reproduced by purified H. influenzae lipooligosaccharide. Consistent with a functional role for this response, induction of ICAM-1 by H. influenzae mediated increased neutrophil adherence to the epithelial cell surface. Furthermore, in an in vivo murine model of airway infection with H. influenzae, increased epithelial cell ICAM-1 expression coincided with increased chemokine levels and neutrophil recruitment in the airway. These results indicate that ICAM-1 expression on human respiratory epithelial cells is induced by epithelial cell interaction with H. influenzae and suggest that an ICAM-1-dependent mechanism can mediate neutrophil adherence to these cells independent of inflammatory mediator release by other cell types. Direct induction of specific epithelial cell genes (such as ICAM-1 and IL-8) by bacterial infection may allow for rapid and efficient innate defense in the airway.
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PMID:Haemophilus influenzae stimulates ICAM-1 expression on respiratory epithelial cells. 1075 14

Mice lacking surfactant protein (SP)-A (SP-A-/-) or SP-D (SP-D-/-) and wild-type mice were infected with group B streptococcus or Haemophilus influenzae by intratracheal instillation. Although decreased killing of group B streptococcus and H. influenzae was observed in SP-A-/- mice but not in SP-D-/- mice, deficiency of either SP-A or SP-D was associated with increased inflammation and inflammatory cell recruitment in the lung after infection. Deficient uptake of bacteria by alveolar macrophages was observed in both SP-A- and SP-D-deficient mice. Isolated alveolar macrophages from SP-A-/- mice generated significantly less, whereas those from SP-D-/- mice generated significantly greater superoxide and hydrogen peroxide compared with wild-type alveolar macrophages. In SP-D-/- mice, bacterial killing was associated with increased lung inflammation, increased oxidant production, and decreased macrophage phagocytosis. In contrast, in the absence of SP-A, bacterial killing was decreased and associated with increased lung inflammation, decreased oxidant production, and decreased macrophage phagocytosis. Increased oxidant production likely contributes to effective bacterial killing in the lungs of SP-D-/- mice. The collectins, SP-A and SP-D, play distinct roles during bacterial infection of the lung.
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PMID:Distinct effects of surfactant protein A or D deficiency during bacterial infection on the lung. 1103 1

A minority of patients with common cold and upper respiratory tract infections have a bacterial infection and may benefit from antibiotic therapy. The present analysis set out to determine whether there were clinical symptoms or signs which could help the clinician to identify a subset of patients with moderate forms of acute rhinosinusitis who are infected with pathogenic bacteria. Detailed clinical history and medical examination were obtained from 265 patients (mean age 35 years, 138 females and 127 males) presenting symptoms of upper respiratory tract infections but no fever above 38 degrees C. The presence of three pathogenic bacteria (S. pneumoniae, H. influenzae or M. catarrhalis) was determined in all patients by culture of nasopharyngeal secretions. Aggravating factors for severity of rhinosinusitis, such as severe nasal obstruction, inferior and/or middle turbinate hypertrophy, oedema of the middle meatus mucosa and septal defects, were not associated with the presence of bacteria. Pathogenic bacteria were found in 77 patients (29%). The clinical signs and symptoms which were significantly associated in a multivariate model with the presence of bacteria included facial pain (p < 0.003), coloured nasal discharge (p < 0.003) and radiological maxillary sinusitis (complete opacity, air-fluid level or mucosal thickening greater than 10 mm) (p < 0.002). This, the best predictive model, had a sensitivity of 69% and a specificity of 64% and therefore could not be used either as a screening tool or as a diagnostic criterion for bacterial rhinosinusitis. We conclude that signs and symptoms of acute rhinosinusitis in patients with a mild to moderate clinical presentation are poor predictors of the presence of bacteria. In agreement with previous studies, culture of nasopharyngeal secretions may identify patients who would benefit from antibiotic treatment. Thus, antibiotic therapy should not be prescribed in the absence of bacteriological evidence.
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PMID:[Symptoms and clinical and radiological signs predicting the bacterial origin of acute rhinosinusitis]. 1114 33

Acute otitis media is the most common bacterial infection in the child under 5 years of age and the leading reason for antibiotic prescriptions in Western countries. The choice of optimal antibiotic treatment is based essentially on microbiologic epidemiologic studies. The bacteria most often responsible for otitis belong to the commensal flora of the nasopharynx. French studies using paracentesis show that the main bacteria responsible for acute otitis media are H. influenzae, S. pneumoniae and M. catarrhalis. The epidemiology of resistance to antibiotics has recently changed, with the appearance of pneumococcal strains having reduced sensitivity to penicillin, and which have played a major role in treatment failures.
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PMID:[Microbiology in acute otitis media]. 1176 28

A minority of patients with upper respiratory tract infections (URTI) have a bacterial infection and may benefit from antibiotherapy. In previous investigations we showed that in patients suffering from acute rhinosinusitis associated with the presence of Streptococcus pneumoniae, Haemophilus influenzae or Moraxella catarrhalis in their nasopharygeal secretions, resolution of symptoms was significantly improved by antibiotic treatment. The present analysis was performed to determine whether specific clinical symptoms or signs observed during careful endoscopic examination of the nasal cavities could help the clinician to identify a subset of patients with moderate forms of acute rhinosinusitis infected with pathogenic bacteria. Detailed clinical histories were obtained and medical examinations performed in 265 patients (138 females, 127 males; mean age 35 years) presenting with a < 4-week history of URTI symptoms but who did not require immediate antibiotic therapy for severe rhinosinusitis. The presence of three pathogenic bacteria (S. pneumoniae, H. influenzae and M. catarrhalis) was determined in all patients by culture of nasopharyngeal secretions. Azithromycin (500 mg/day for 3 days; n = 133) or placebo (n = 132) were randomly given to all patients in a double-blind manner. Pathogenic bacteria were found in 77 patients (29%). The clinical signs and symptoms significantly associated in a multivariate model with the presence of bacteria included colored nasal discharge (p < 0.003), facial pain (p < 0.032) and radiologically determined maxillary sinusitis (complete opacity, air-fluid level or mucosal thickening > 10 mm) (p < 0.001). This best predictive model had a sensitivity of 69% and a specificity of 64% and therefore could not be used either as a screening tool or as a diagnostic criterion for bacterial rhinosinusitis. In the group of patients with positive bacterial cultures, resolution of symptoms at Day 7 was observed in 73% of patients treated with azithromycin and in 47% of patients in the placebo group (p < 0.007). We conclude that signs and symptoms of acute rhinosinusitis in patients with mild-to-moderate clinical presentations are poor predictors of the presence of bacteria.
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PMID:Symptoms and clinical and radiological signs predicting the presence of pathogenic bacteria in acute rhinosinusitis. 1193 12


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