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A multivariant modelling method was used to analyse the risk, associated with 22 different factors, of contracting acute otitis media (AOM) in a prospective cohort of 1294 urban children followed up to the age of 17-32 (mean 25) months. By far the most important risk factor was the caring of the child at a day-care centre. The importance of this factor further increased with increasing recurrence of the attacks. Next in order came the existence of sibling(s) with AOM attacks during the follow-up. Prolongation of breastfeeding increased the protection against AOM during the first year of life. The frequency of AOM attacks was lowest around midsummer and highest in early winter.

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f According to studies based on bacterial cultures of middle ear fluids, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis have been the most common pathogens in acute otitis media. However, bacterial culture can be affected by reduced viability or suboptimal growth of bacteria. PCR detects bacterial DNA from samples with greater sensitivity than culture. In the present study, we analyzed the middle ear pathogens with both conventional culture and semiquantitative real-time PCR in 90 middle ear fluid samples obtained from children aged 5 to 42 months during acute otitis media episodes. Samples were tested for the presence of S. pneumoniae, H. influenzae, M. catarrhalis, Alloiococcus otitidis, Staphylococcus aureus, and Pseudomonas aeruginosa. One or more bacterial pathogens were detected in 42 (47%) samples with culture and in 69 (77%) samples with PCR. According to PCR analysis, M. catarrhalis results were positive in 42 (47%) samples, H. influenzae in 30 (33%), S. pneumoniae in 27 (30%), A. otitidis in 6 (6.7%), S. aureus in 5 (5.6%), and P. aeruginosa in 1 (1.1%). Multibacterial etiology was seen in 34 (38%) samples, and M. catarrhalis was detected in most (85%) of those cases. Fifteen signals for M. catarrhalis were strong, suggesting a highly probable etiological role of the pathogen. In conclusion, even though M. catarrhalis is often a part of mixed flora in acute otitis media, a considerable proportion of cases may be primarily attributable to this pathogen. B acterial culture of middle ear fluid (MEF) has been the standard for etiologic diagnosis of acute otitis media (AOM).Streptococcus pneumoniae is considered the most common bacterial pathogen, followed by Haemophilus influenzae and Moraxella catarrhalis (1-3). About 44% to 75% of MEF samples are positive for bacterial pathogens in conventional culture (2, 4). However, the proportions of culture-positive MEF samples decrease in patients with recurrent AOM (5) and in patients with treatment failure (6). Host defense mechanisms and previous antibiotic treatments may directly contribute to diminished survival of the pathogens in clinical samples and diminish the likelihood of detection of bacteria by culture. In addition, the presence of bacterial biofilms has been correlated with negative bacterial cultures (7) and some of the bacterial pathogens, e.g., Alloiococcus otitidis, grow poorly in conventional cultures (8).Virus infections have also been considered causative agents in AOM (2, 9). Preceding or concurrent viral upper respiratory tract infection is typical in AOM (10), and interactions of viruses and bacteria in the nasopharynx may play an important role in the pathogenesis of AOM (10-12). In the era of increasing antimicrobial resistance, precise information concerning MEF pathogens may be beneficial for empirical antibiotic therapy, and therefore PCR technique applied to samples from this primarily sterile site may help to achieve more-accurate bacterial etiologic diagnosis of AOM.Previous studies of AOM in Finnish pop...

Although S. pneumoniae, H. influenzae, and M. catarrhalis have been long established as the most important pathogens in acute otitis media using culture and specific PCR assays, the knowledge of their mutual quantitative relations and possible roles of other bacteria is incomplete. The advent of unbiased bacteriome 16S rRNA gene profiling has allowed the detection of nearly all bacteria present in the sample, and it helps in depicting their mutual quantitative ratios. Due to the difficulties in performing mass sequencing in low-volume samples, only a few bacteriome-profiling studies of otitis media have been published, all limited to cases of chronic otitis media. Here, we present a study on samples obtained from young children with acute otitis media, successfully using a strategy of nested PCR coupled with mass sequencing, and demonstrate that the method can confer quantitative information hardly obtainable by other methods.