Ultrastructure of Streptococcus pneumoniae after exposure to xylitol.
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OBJECTIVES: Xylitol is a sugar alcohol which reduces the growth of Streptococcus pneumoniae and the adherence of pneumococci and Haemophilus influenzae to nasopharyngeal cells. Xylitol prevents acute otitis media but does not decrease nasopharyngeal carriage of pneumococci. We hypothesized that xylitol could affect the surface structures of viable pneumococci, which would further explain the mechanism of action of xylitol in preventing acute otitis media. METHODS: We exposed five strains of pneumococci to 0.5%-5% xylitol, 5% glucose, 5% fructose and 5% sorbitol or control medium (brain heart infusion) for 0.5-2 h and examined the ultrastructure of bacteria by electron microscopy. RESULTS: The cell wall of pneumococci became more diffuse, the polysaccharide capsule became ragged and the proportion of damaged pneumococci increased after exposure to xylitol for 2 h, but not after exposure to other sugars or control medium. The phenotype of all pneumococcal strains was opaque before xylitol exposure and became almost transparent both in xylitol and in control medium during the experiment. CONCLUSIONS: This study demonstrates further that xylitol has a harmful effect on pneumococci. The observed changes in the polysaccharide capsule and the cell wall of pneumococci could affect the adherence and virulence of pneumococci, explaining the good clinical efficacy of xylitol in the prevention of acute otitis media. (+info)
The immunoregulatory and allergy-associated cytokines in the aetiology of the otitis media with effusion.
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Inflammation in the middle ear mucosa, which can be provoked by different primary factors such as bacterial and viral infection, local allergic reactions and reflux, is the crucial event in the pathogenesis of otitis media with effusion (OME). Unresolved acute inflammatory responses or defective immunoregulation of middle inflammation can promote chronic inflammatory processes and stimulate the chronic condition of OME. Cytokines are the central molecular regulators of middle ear inflammation and can switch the acute phase of inflammation in the chronic stage and induce molecular-pathological processes leading to the histopathological changes accompanying OME. In this review we present cytokines identified in otitis media, immunoregulatory [interleukin (IL)-2, IL-10, transforming growth factor-beta]) and allergy associated (IL-4, IL-5, granulocyte-macrophage colony-stimulating factor), as crucial molecular regulators, responsible for chronic inflammation in the middle ear and the chronic condition of OME. (+info)
Predictors of hearing loss in school entrants in a developing country.
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BACKGROUND: Hearing loss is a prevalent and significant disability that impairs functional development and educational attainment of school children in developing countries. Lack of a simple and practical screening protocol often deters routine and systematic hearing screening at school entry. AIM: To identify predictors of hearing loss for a practical screening model in school-aged children. SETTINGS AND DESIGN: Community-based, retrospective case-control study of school entrants in an inner city. METHODS: Results from the audiologic and non-audiologic examination of 50 hearing impaired children in randomly selected mainstream schools were compared with those of a control group of 150 normal hearing children, matched for age and sex from the same population. The non-audiologic evaluation consisted of medical history, general physical examination, anthropometry, motor skills, intelligence and visual acuity while the audiologic assessment consisted of otoscopy, audiometry and tympanometry. STATISTICAL ANALYSIS: Multiple logistic regression analysis of significant variables derived from univariate analysis incorporating student t-test and chi-square. RESULTS: Besides parental literacy (OR:0.3; 95% CI:0.16-0.68), non-audiologic variables showed no association with hearing loss. In contrast, most audiologic indicators, enlarged nasal turbinate (OR:3.3; 95% CI:0.98-11.31), debris or foreign bodies in the ear canal (OR:5.4; 95% CI:1.0-36.03), impacted cerumen (OR:6.2; 95% CI:2.12-14.33), dull tympanic membrane (OR:2.2; 95% CI:1.10-4.46), perforated ear drum (OR:24.3; 95% CI:2.93-1100.17) and otitis media with effusion OME (OR:14.2; 95% CI:6.22-33.09), were associated with hearing loss. However, only parental literacy (OR:0.3; 95% CI:0.16-0.69), impacted cerumen (OR:4.0; 95% CI:1.66-9.43) and OME (OR:11.0; 95% CI:4.74-25.62) emerged as predictors. CONCLUSION: Selective screening based on the identification of impacted cerumen and OME will facilitate the detection of a significant proportion of hearing impaired school entrants. (+info)
Antibiotics for otitis media with effusion.
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Otitis media with effusion (OME) is defined as asymptomatic middle-ear effusion, that is, without the signs and symptoms of acute otitis media (AOM), such as fever, otalgia, or otorrhea. OME can occur after an episode of AOM or may occur without any prior or concurrent symptoms and is often noted on a routine physical examination or screening. Because children with OME are usually not ill, there is a question of whether treatment is warranted for this condition. Also adding to the complexity of this problem is the high spontaneous cure rate of OME. This paper will review the many clinical trials of the efficacy of antimicrobial therapy for OME. We have grouped the studies into 4 major categories: antibiotic vs no treatment, antibiotic vs placebo, antibiotic vs antibiotic, and antibiotic prophylaxis. While study designs, definitions, and quality vary widely, these studies show a trend toward short-term efficacy of antimicrobial treatment, but long-term efficacy is doubtful. In this age of antimicrobial resistance, coupled with the high natural cure rate, routine antimicrobial treatment of OME is not warranted. It may be useful in selected patients, particularly those with chronic OME (3 months or longer of bilateral effusion or 6 months or longer of unilateral effusion) for whom surgery is being considered: a 1-time short course of antibiotic may allow cancellation or at least postponement of a surgical procedure, particularly in spring/summer when one would like to avoid placing tubes in the ears and placing the child at risk for otorrhea due to water exposure. Also, antimicrobial therapy may provide at least short-term relief for symptomatic children (hearing loss, developmental delay, etc.) for whom surgery must be postponed or is contraindicated. (+info)
Detection rates of bacteria in chronic otitis media with effusion in children.
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This study was performed to investigate polymerase chain reaction-based detection of bacterial DNA in middle ear fluid and assess the correlation between the PCR-positive rate with several factors associated with middle ear effusion. The purpose was to gain a further understanding of bacterial infection as a major cause of otitis media with effusion. Of the 278 specimens of middle ear fluid, 39 (14%) tested positive by ordinary culture. The overall detection rate of bacterial DNA using the PCR method was 36.7% for middle ear effusion, and bacterial DNA detection rates of Hemophilus influenzae, Streptococcus pneumoniae, Moraxella catarrhalis in the middle ear effusion were 29.1%, 4.7% and 10.8%, respectively. The bacterial DNA detection rate was higher in ears with a history of acute otitis media than those without the history. High detection rates were observed in patients younger than 48 months who have had a higher tendency to present with acute otitis media. We concluded that PCR is a more sensitive method for the detection of bacteria in middle ear effusion than ordinary culture, and acute otitis media is a major contributor to the pathogenesis of otitis media with effusion. (+info)
Clinical diagnostic accuracy of otitis media with effusion in children, and significance of myringotomy: diagnostic or therapeutic?
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The specific aims of this prospective survey were to determine the accuracy of traditional diagnostic tools, such as pneumatic otoscopy, otomicroscopy, and tympanometry, and evaluate the usefulness of myringotomy as a diagnostic method; also to determine the significance of myringotomy in treating otitis media with effusion (OME). The status of middle ear of 51 children (85 ears) from November 2002 to February 2003 was examined using pneumatic otoscopy, otomicroscopy, and tympanometry, and the presence/absence of middle ear effusion was confirmed by myringotomy. The otomicroscopy was the most sensitive and specific one among three diagnostic tools. But, it had some false positive cases. This study failed to show the therapeutic efficacy of myringotomy. Otomicroscopy seems to have the potential to become the standard for diagnosis of OME and for validation of pneumatic otoscopy in children. However, when otoscopic, otomicroscopic findings and tympanogram of suspected ear show poor correlation, myringotomy can be used to confirm the presence of OME, as the diagnostic modality. As the therapeutic modality, we think that it is proper to limit indications of myringotomy to some selected cases. (+info)
Emergence of penicillin-nonsusceptible Streptococcus pneumoniae clones expressing serotypes not present in the antipneumococcal conjugate vaccine.
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BACKGROUND: Penicillin-nonsusceptible Streptococcus pneumoniae isolates are confined mainly to a few serogroups. Capsular transformation may serve as a mechanism for spreading antibiotic resistance to new serotypes. METHODS: Antibiogram and molecular typing, by pulsed-field gel electrophoresis (PFGE), were performed on 46 nasopharyngeal and middle ear fluid (MEF) isolates expressing serotype 11A, 45 MEF isolates expressing serotype 15B/C (recovered during 1998-2003 from Israeli children <5 years old), and 57 MEF isolates expressing serotype 19F (recovered during 1998-2001 from Costa Rican children <7.5 years old). RESULTS: PFGE patterns showed that 49 (86%) of 57 serotype 19F isolates and 19 (41%) of 46 serotype 15B/C isolates were closely related. The vast majority of these isolates (80% of serotype 19F and 100% of serotype 15B/C isolates) were nonsusceptible to penicillin. Multilocus sequence typing (MLST) data show that the serotype 15B/C isolates belonged to the ST346 cluster, whereas the serotype 19F isolates were a single-locus variant of ST346. For serotype 11A isolates, PFGE patterns and MLST analysis showed that 8 (80%) of the 10 penicillin-nonsusceptible isolates belonged to a single clone--namely, ST156--which was identical to the international Spain9V-3 clone. CONCLUSIONS: Penicillin-nonsusceptible pneumococcal clones of serotypes not related to those included in the 11-valent conjugate vaccines may derive from capsular transformation of vaccine-related serotypes. Of particular concern was the detection of serotype 11A variants of the successful international Spain9V-3 clone. This phenomenon, although seemingly rare at present, can have implications for the long-term effectiveness of the conjugate vaccines. (+info)
A randomized, double-blind, placebo-controlled noninferiority trial of amoxicillin for clinically diagnosed acute otitis media in children 6 months to 5 years of age.
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OBJECTIVES: Debate continues with respect to a "watch and wait" approach versus immediate antibiotic treatment for the initial treatment of acute otitis media. In this double-blind noninferiority trial, we compared clinical improvement rates at 14 days for children (6 months to 5 years of age) with acute otitis media who were randomly assigned to receive amoxicillin or placebo. METHODS: We enrolled healthy children who presented to clinics or the emergency department with a new episode of acute otitis media during the fall and winter months in Ottawa (from December 1999 to the end of March 2002). The children were randomly assigned to receive amoxicillin (60 mg/kg daily) or placebo for 10 days. Telephone follow-up was performed on each of days 1, 2 and 3 and once between day 10 and day 14. The primary outcome was clinical resolution of symptoms, defined as absence of receipt of an antimicrobial (other than the amoxicillin in the treatment group) at any time during the 14-day period. Secondary outcomes were the presence of pain and fever and the activity level in the first 3 days, recurrence rates, and the presence of middle ear effusion at 1 and 3 months. RESULTS: According to clinical scoring, 415 of the 512 children who could be evaluated had moderate disease. At 14 days 84.2% of the children receiving placebo and 92.8% of those receiving amoxicillin had clinical resolution of symptoms (absolute difference -8.6%, 95% confidence interval -14.4% to -3.0%). Children who received placebo had more pain and fever in the first 2 days. There were no statistical differences in adverse events between the 2 groups, nor were there any significant differences in recurrence rates or middle ear effusion at 1 and 3 months. INTERPRETATION: Our results did not support the hypothesis that placebo was noninferior to amoxicillin (i.e., that the 14-day cure rates among children with clinically diagnosed acute otitis media would not be substantially worse in the placebo group than the treatment group). Nevertheless, delaying treatment was associated with resolution of clinical signs and symptoms in most of the children. (+info)