Biomedical subjects

Ritva Syrjänen

Publications and source records attributed to Ritva Syrjänen.

8 recordsLinked to original sources

PubMed2005

Is there any specific association between respiratory viruses and bacteria in acute otitis media of young children?

BACKGROUND: Respiratory viral infections are usually preceding or coinciding with acute otitis media (AOM) in children. It is not known if a given viral infection would facilitate invasion of bacterial pathogens into the middle ear in a species-specific way. We reanalysed the microbiological results of the two prospective Finnish Otitis Media (FinOM) studies for this purpose. METHODS: The children had been followed from 2 months to 2 years of age in specific study clinics and all referred AOM events were analysed. Combined results of virus detection tests from middle ear fluid and nasopharyngeal aspirate and those of bacterial culture from middle ear fluid were cross-tabulated for 529 AOM events in the FinOM Cohort Study and for 364 events in the FinOM Vaccine Trial. RESULTS: In both studies the main bacterial pathogens were Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis while the main viruses detected were rhinoviruses and respiratory syncytial virus (plus enteroviruses in the Vaccine Trial). No distinct species-specific associations were observed between the viral and bacterial findings. CONCLUSION: We did not find support to the theory that respiratory infection caused by a given viral species would favour growth of a certain bacterial pathogen in the MEF more than another.

Bacterial Infections↗

PubMed2005

Diagnostic value of tympanometry using subject-specific normative values.

OBJECTIVE: Tympanometry has proven valuable in the diagnosis of otitis media in infants. The classification used in the Finnish otitis media studies has resulted in high specificity yet only moderate sensitivity. We aimed to explore the benefit of using each subject's individual previous test results (obtained at previous visits of the children when diagnosed healthy) as normative values. Specific aim was to assess this approach in increasing sensitivity in the diagnosis of otitis media. METHODS: We used tympanometric (GrasonStadler GSI 38) results of children in the Finnish otitis media vaccine trial obtained at pre-scheduled 7-month visits (if ears found healthy) and at the first subsequent sick visit with respiratory infections and potential otitis media within a 90-day period after the 7-month visit. Children with recent otitis media within the previous month and tympanometric tests with documented interfering factors were excluded. Pneumatic otoscopy was used as the reference method for the diagnosis of otitis media. RESULTS: Altogether 2476 children at the 7-month visits were examined; after exclusions data on 1759 children were available for analysis. Of these children, 630 were brought to at least one sick visit defined above. Finally, data on 906 ears were available for analysis. Entirely flat type B tympanograms predicted otitis media accurately; also high-peaked tympanograms were accurate in predicting normal middle ear status. For the moderate-peaked curves in-between, absolute and relative changes in the tympanometric variables from the 7-month visit to the sick visit were explored for accurate prediction of otitis media; decrease in curve height by at least 2/3 was found most valuable. Sensitivity of the type B tympanogram was 61% and specificity 99% at the sick visit. The sensitivity increased to 67% with a specificity of 98%, if results with the ratio of static acoustic admittance (height of the curve) at the sick visit compared to the previous healthy visit <0.35 were also considered abnormal together with type B curve in indicating otitis media. CONCLUSIONS: The subject-specific normative values were not found especially useful, although a slight increase in sensitivity was achieved without compromizing specificity.

Acoustic Impedance Tests↗

PubMed2005

Using multilocus sequence data to define the pneumococcus.

We investigated the genetic relationships between serotypeable pneumococci and nonserotypeable presumptive pneumococci using multilocus sequence typing (MLST) and partial sequencing of the pneumolysin gene (ply). Among 121 nonserotypeable presumptive pneumococci from Finland, we identified isolates of three classes: those with sequence types (STs) identical to those of serotypeable pneumococci, suggesting authentic pneumococci in which capsular expression had been downregulated or lost; isolates that clustered among serotypeable pneumococci on a tree based on the concatenated sequences of the MLST loci but which had STs that differed from those of serotypeable pneumococci in the MLST database; and a more diverse collection of isolates that did not cluster with serotypeable pneumococci. The latter isolates typically had sequences at all seven MLST loci that were 5 to 10% divergent from those of authentic pneumococci and also had distinct and divergent ply alleles. These isolates are proposed to be distinct from pneumococci but cannot be resolved from them by optochin susceptibility, bile solubility, or the presence of the ply gene. Complete resolution of pneumococci from the related but distinct population is problematic, as recombination between them was evident, and a few isolates of each population possessed alleles at one or occasionally more MLST loci from the other population. However, a tree based on the concatenated sequences of the MLST loci in most cases unambiguously distinguished whether a nonserotypeable isolate was or was not a pneumococcus, and the sequence of the ply gene fragment was found to be useful to resolve difficult cases.

Chromosome Mapping↗

PubMed2004

Presence of specific viruses in the middle ear fluids and respiratory secretions of young children with acute otitis media.

The purpose of the study was to investigate the presence of different viruses in middle ear fluids and nasopharyngeal aspirates in young children with acute otitis media. Two cohorts of children (N = 329 and 611) were followed from 2 to 24 months of age in Finland in two prospective studies (Finnish Otitis Media Cohort Study and Finnish Otitis Media Vaccine Trial). During the study period, nasopharyngeal and middle ear fluid specimens for each acute otitis media event were examined for eight (Cohort Study) or ten (Vaccine Trial) common respiratory viruses; adenoviruses, influenza viruses A and B, parainfluenza viruses 1, 2, and 3, respiratory syncytial virus (RSV), enteroviruses, parechoviruses, and rhinoviruses. Picornaviruses (rhinoviruses, enteroviruses, and parechoviruses) were determined by reverse transcription PCR while antigen detection was used for the other viruses. A virus was present in either nasopharyngeal or middle ear specimen in 54% of events in the first cohort and in 67% of events in the second. Rhinoviruses formed the most common virus group detected (41-32%), followed by enteroviruses (25%, sought in the second cohort only) and respiratory syncytial virus (RSV) (10%). All the other viruses represented jointly 8-10% of the events. In conclusion, using the methods described in this study, a specific virus infection was diagnosed in two thirds of all acute otitis media events in young children. Picornavirus RNA was detected in association with more than a half of all acute otitis media events. The use of PCR-based methods for the other respiratory viruses might have increased further the overall virus detection rate in acute otitis media.

Acute Disease↗

PubMed2004

Ability of pneumococcal serotypes and clones to cause acute otitis media: implications for the prevention of otitis media by conjugate vaccines.

The relative abilities of pneumococcal serotypes and strains (clones) to cause acute otitis media (AOM) were investigated by comparing the serotypes and genotypes of pneumococci recovered from cases of AOM (n = 149) in children <2 years of age with those from nasopharyngeal carriage (n = 288) in age-matched controls from the same region. The odds ratio (OR) for association of pooled vaccine serotypes with AOM was found to be slightly elevated over unity, although this was not significantly different from that of pooled nonvaccine or vaccine-related serotypes. Comparing individual serotypes, 19F and 23F had 2- to 2.5-fold higher ORs, although these were not markedly different from the ORs of nonvaccine serotypes. None of the major clones had an OR that was significantly greater than the average, and the differences in ORs among serotypes and clones were much less than those for invasive disease, suggesting little variation in their ability to cause AOM. We conclude that serotype replacement may reduce the long-term efficacy of these vaccines against AOM.

Acute Disease↗

PubMed2003

Nasopharyngeal carriage of anaerobes during health and acute otitis media by two years of age.

The nasopharyngeal acquisition of anaerobic bacteria was longitudinally examined among a homogeneous group of Caucasian infants by 2 years of age. Nasopharyngeal swab (NP) samples were collected at scheduled healthy visits at 2, 6, 12, 18, and 24 months of age, and nasopharyngeal aspirates (NPA) during every visit for acute otitis media (AOM). The infants were divided into 4 groups according to the number (0, 1, 2-3, and > 3) of AOM episodes experienced by 2 years of age. At 2 years, the cumulative carriage rates of anaerobic species in these infant groups were 29%, 62%, 89%, and 89%, respectively. Anaerobic species were found in 15/220 (6.8%) of the NP samples and in 34/71 (47.9%) of the NPA samples. Our present results indicate that anaerobic species do not belong to the indigenous nasopharyngeal microflora but only transiently colonize the nasopharynx during AOM.

Acute Disease↗

PubMed2003

Emergence of penicillin resistance among Fusobacterium nucleatum populations of commensal oral flora during early childhood.

Penicillin resistance due to beta-lactamase production is surprisingly common among oral bacteria in childhood. Fusobacterium nucleatum, a Gram-negative anaerobic bacillus, is a member of the developing oral commensal flora. As part of the investigation on the emergence of oral bacterial resistance, the aim of the present study was to examine longitudinally the penicillin resistance among salivary F. nucleatum populations as related to age, day care attendance and sibling history, and exposure to antimicrobial agents. Altogether 1492 F. nucleatum isolates from saliva of 44 healthy infants followed at a study clinic at 2, 6, 12, 18 and 24 months of age were tested for beta-lactamase production. Furthermore, the 276 beta-lactamase-positive isolates were examined for their in vitro susceptibility to penicillin G by the NCCLS-approved agar dilution method. Statistical analysis of the associations between penicillin-resistant isolates and infants' age, day care attendance, number of siblings and their ear infections, and exposure to antimicrobial agents was performed by SPSS Windows Version 10. The prevalence of infants harbouring beta-lactamase-producing F. nucleatum strains increased from 2% to 49% during the follow-up time. In nearly all cases beta-lactamase-producing F. nucleatum isolates were found simultaneously with beta-lactamase-negative isolates. Most beta-lactamase-producing isolates (80%) showed an MIC of > or =8 mg/L. In conclusion, the prevalence of infants harbouring penicillin-resistant F. nucleatum due to beta-lactamase production increased with age and usage of antimicrobial agents during the first year of life.

Anti-Bacterial Agents↗

PubMed2002

Common respiratory infections early in life may reduce the risk of atopic dermatitis.

Infections that occur early in life may protect against atopic disease later in life. To investigate the relationship between common acute respiratory infections and atopic dermatitis in early childhood, we closely observed a cohort of 329 children from the ages of 2 to 24 months. We assessed the effect of proven viral infections and acute otitis media on the occurrence of atopic dermatitis. If the child had his or her first respiratory infection before the age of 6 months, the child's remaining risk of developing atopic dermatitis was reduced by 49% (95% confidence interval, -24% to 79%). The individual risk of developing atopic dermatitis was similarly reduced after infection experienced at >/=6 months of age, but the remaining risk was low, because most cases of atopic dermatitis had manifested by this time. Our results are consistent with the hypothesis that early infections may reduce the risk of atopic disease.

Child↗