Biomedical subjects

Elja Herva

Publications and source records attributed to Elja Herva.

8 recordsLinked to original sources

PubMed2006

Field evaluation of the chessboard modification for serotyping of Streptococcus pneumoniae in a small laboratory in Bangladesh.

The chessboard modification of the quellung method for serotyping Streptococcus pneumoniae (Pneumococcus) was introduced in the Gonoshasthaya Vaccine Research Laboratory, a small laboratory in Bangladesh. We applied initial bench-side training and subsequent continuous surveillance and quality assurance as approaches for good laboratory practice. Results obtained a this laboratory on 1,101 consecutive isolates had satisfactory sensitivity (85.1-100%) and specificity (97.9-99.9%) for serotyping the 10 most common serogroups/types of pneumococci when compared with the results obtained in the Finnish reference laboratory for pneumococcal serotyping at the National Public Health Institute. We conclude that serotyping of pneumococci by the chessboard method can be introduced into a small laboratory by providing basic bacteriologic skills, adequate initial training, and continuous external support.

Adult↗

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

Real-time pneumolysin polymerase chain reaction with melting curve analysis differentiates pneumococcus from other alpha-hemolytic streptococci.

The majority of pneumococcal isolates can be identified by the conventional methods based on phenotypic characteristics. Occasionally, however, the differentiation of alpha-hemolytic streptococci from pneumococci, especially those isolated from nasopharynx, is problematic due to the discrepant results obtained by the conventional identification methods. Several gene technological methods based on the amplification of genes encoding pneumococcal virulence factors, such as pneumolysin (ply) and autolysin, have been used as additional identification methods. Recent studies have shown that especially the ply gene is frequently also present in nonpneumococcal alpha-hemolytic streptococci. In this study, we compared the commonly used phenotypic identification methods with nucleic acid-based methods, commercial AccuProbetrade mark, conventional pneumolysin polymerase chain reaction (Ply-PCR), and real-time Ply-PCR in the identification of alpha-hemolytic streptococcal strains isolated from 100 consecutive nasopharyngeal specimens. We also studied if melting curve analysis and sequencing of the amplification products of a ply gene fragment could be helpful in the identification. Our results suggest that the ply gene present in alpha-hemolytic streptococci differs from that present in pneumococcus, and that melting curve analysis would prove useful in the differentiation of these bacteria.

Bacterial Proteins↗

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

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↗

PubMed2004

Survival of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis frozen in skim milk- tryptone-glucose-glycerol medium.

In STGG (skim milk, tryptone, glucose, glycerol) medium at -80 degrees C, Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis isolates survived for at least 3 years, and the same species have survived in nasopharyngeal swabs for at least 1.5 years. At -20 degrees C, S. pneumoniae and M. catarrhalis survived for 1.5 years, but H. influenzae survived for only 2 months.

Animals↗

PubMed2003

Association of clinical signs and symptoms with bacterial findings in acute otitis media.

In acute otitis media (AOM), a means of prediction of the bacterial pathogen based on symptoms and signs would be valuable in selecting appropriate antimicrobial treatment. Children in the control arm (n=831) in the Finnish Otitis Media Vaccine Trial were prospectively observed in a study clinic setting from the age of 2 to 24 months. In patients with AOM, myringotomy with aspiration was performed, and middle ear fluid samples were cultured for bacterial pathogens. Symptoms and signs of respiratory infections were thoroughly recorded. Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae were the most common bacterial pathogens. Pneumococcal AOM was associated with more-severe AOM characterized by fever and earache. AOM due to H. influenzae was associated with eye symptoms and findings. Accurate prediction of a bacterial cause of infection based on symptoms and signs of AOM was not possible, but a specific cause was predicted in some situations, with a high probability of applicability to clinical practice.

Acute Disease↗

PubMed2003

Prevention of otitis media by adenoidectomy in children younger than 2 years.

OBJECTIVES: To test the effect of adenoidectomy in connection with tympanostomy compared with tympanostomy only in preventing otitis media in children younger than 2 years. DESIGN: Prospective trial with randomized and nonrandomized arms. SETTING: Primary care study clinics. PARTICIPANTS AND INTERVENTIONS: The study participants were selected from 2497 children who had been enrolled in the Finnish Otitis Media Vaccine Trial at the age of 2 months. A total of 306 children, aged 1 to 2 years, who had experienced recurrent episodes of otitis media were randomized into 2 treatment groups: tympanostomy with or without adenoidectomy. Of the 306 children, 137 were operated on according to random basis (randomized trial). The 169 children whose parents declined participation in the randomized trial were operated on according to the parents' preferences (nonrandomized trial). All children were followed up until 2 years of age. The mean follow-up time was 7 months. MAIN OUTCOME MEASURE: The rate of acute otitis media episodes. RESULTS: The average reduction in the rate of all acute otitis media episodes in the adenoidectomy group was 19% (95% confidence interval [CI], -14% to 43%) among children enrolled in the randomized trial and 25% (95% CI, -13% to 50%) in the nonrandomized trial. The reduction in the randomized trial was mainly due to reduction in the rate of pneumococcal otitis media (58%, 95% CI, 16%-79%). CONCLUSION: In children younger than 2 years, concurrent adenoidectomy during the insertion of tympanostomy tubes does not seem to have a major advantage over the insertion of tympanostomy tubes alone in preventing otitis media.

Adenoidectomy↗