Marjaana Kleemola

Epidemiology of documented viral respiratory infections and acute otitis media in a cohort of children followed from two to twenty-four months of age.

Background. Viral upper respiratory infections (URIs) are considered major risk factors for acute otitis media (AOM) in young children. We studied the epidemiology and relative roles of different viruses in respiratory infections in a cohort of 329 Finnish children followed from 2 months to 2 years of age. Methods. A nasopharyngeal aspirate (NPA) was collected whenever the child had signs and/or symptoms of URI and tested for the presence of common respiratory virus antigens or infectivity/nucleic acid (only rhinoviruses). Possible repeated detections of a given virus during a 30-day period were considered to represent a single designated virus-specific episode. AOM and URI episodes were defined in a similar way. Results. At least one virus was detected in 837 (41.7%) of the 2005 NPA specimens examined. Rates of URI and virus-specific episodes showed expected seasonal variation with major peak occurrences coinciding with or preceding those of AOM. The proportions of rhinoviruses, respiratory syncytial (RS) virus, parainfluenza virus (PIV) type 3, influenza virus A and adenoviruses were 63.1, 14.7, 6.7, 6.7 and 6.2% of the total of 761 virus-specific episodes. Influenza virus B, PIV1 and PIV2 were each responsible for ∼1% of the episodes. AOM was diagnosed in 870 URI cases (43.4%) and in 43.3% of cases associated with a virus-positive NPA. The latter figure was clearly higher (57.7%) for RS virus-positive specimens. Conclusions. The seasonal coincidence of URI and AOM demonstrated the obvious role of URI in the pathogenesis of AOM. The occurrence of rhinoviruses and RS virus in URI was strikingly more common than that of any other virus tested. Although rhinoviruses were definitely the most frequently found viruses in NPA specimens, the association of RS virus with concurrent AOM was relatively higher than that of any other virus.

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. J. Med. Virol. 72:241–248, 2004.

Bacterial antibody assays in the diagnosis of acute lower respiratory tract infection in children

Bacterial antibodies were studied in acute, intermediate and convalescent phase sera (mean duration from first to last sample 36 days) of 121 children hospitalized for acute lower respiratory tract infection. Antibody responses were observed in 45% of all cases and in 29% of the 21 children < 1 year old. A total of 15 responses to Streptococcus pneumoniae (pneumolysin), 20 to Haemophilus influenzae, 9 to Moraxella catarrhalis, 3 to chlamydiae and 8 to Mycoplasma pneumoniae were found. In 79 patients with 4 consecutive samples available, 52% of the 31 responses were measurable within 5 days from admission. Overall the responses were not associated with upper respiratory tract bacterial findings or acute otitis media. Significantly more responses were found in the 121 children with acute lower respiratory tract infection than in healthy controls (P < 0.007). We conclude that bacterial antibody assays provide a useful tool in the study of the etiology of acute lower respiratory tract infection in young children, even if the interval between paired serum samples is short.

Viral Etiology of Frequently Recurring Respiratory Tract Infections in Children

The viral etiology of frequently recurring respiratory tract infection (FRRI) in children aged <2 years was studied. Altogether, 329 children were followed from 2 to 24 months of age in the Finnish Otitis Media Cohort Study. Children with FRRI were defined as having > or =9 episodes of upper respiratory tract infection (URI) and/or > or =4 episodes of acute otitis media during follow-up. Nasopharyngeal aspirates, middle ear fluid specimens, and serum samples were analyzed for 8 common respiratory viruses. Of 1358 URI episodes, 642 (47%) occurred in the 78 children with FRRI. At least 1 virus was associated with 62% of these episodes, whereas the corresponding figure for children without FRRIs was 54%. The frequency of different viruses was similar in both groups, but the relative proportion of rhinovirus infections was slightly higher among children with FRRI. In conclusion, a specific viral etiology does not explain the excess of URI episodes in children with FRRI.

Serum eosinophil cationic protein as a predictor of wheezing after bronchiolitis

We have evaluated the role of eosinophil cationic protein (ECP) concentrations in serum in predicting wheezing after bronchiolitis, during infancy and early childhood. A prospective study at a university hospital serving all pediatric patients in a defined area was designed. Serum ECP concentrations were measured in 92 infants under the age of 2 years on admission for acute bronchiolitis, and 6 and 16 weeks after hospitalization. Nebulized anti‐inflammatory therapy was initiated during hospitalization: 32 patients received cromolyn sodium and 32 patients received budesonide for 16 weeks; 30 control patients received no maintenance therapy. The numbers of subsequent physician‐diagnosed wheezing episodes and hospital admissions for obstructive airway disease were recorded during 16 weeks of follow‐up.

Nasopharyngeal eosinophil cationic protein in bronchiolitis

A prospective 4‐month follow‐up of children hospitalized with bronchiolitis revealed that high concentrations of eosinophil cationic protein (ECP) in nasopharyngeal aspirates (NPA) are predictive of wheezing after bronchiolitis. In the 29 patients who received no anti‐inflammatory therapy the median concentration of NPA ECP was 882 ng/g in those with physician‐diagnosed wheezing and 154 ng/g in those without subsequent physician‐diagnosed wheezing (P = 0.02). The NPA ECP concentrations of the whole study group of 88 children with and without subsequent hospital admissions for wheezing were 531 and 299 ng/g, respectively (P = 0.02). At entry the children with negative viral findings had significantly higher concentrations of respiratory tract ECP than those with positive viral findings (515 vs. 240 ng/g; P = 0.01). The concentration of ECP in respiratory secretions decreased significantly after bronchiolitis (P = 0.01) provided that no new viral or mycoplasmal infection occurred. NPA ECP values decreased in relation to time regardless of whether anti‐inflammatory therapy was used or not. Children with high concentrations of respiratory tract ECP seemed to benefit from anti‐inflammatory therapy with nebulized cromolyn sodium or budesonide; both drugs significantly decreased the number of subsequent physician‐diagnosed bronchial obstructions (P = 0.0006), and they tended to decrease the number of hospital admissions for wheezing (P = 0.08). Our results suggest that high concentrations of ECP in respiratory tract secretions in children with bronchiolitis reflect the presence of eosinophilic inflammation also seen in asthma. Pediatr. Pulmonol. 1997;24:35–41.

Serological diagnosis of influenza A and B infections by enzyme immunoassay. Comparison with the complement fixation test

Paired sera from 784 patients with symptoms of acute respiratory disease were examined for antibodies against influenza A, B and parainfluenza (1 and 3) viruses by complement fixation (CF) and enzyme immunoassay (EIA). The internal variation of the EIA test results was low and an increase of 0.250 in absorbance values which corresponded to a two-fold increase in end-point titres was considered a diagnostic antibody rise. EIA detected significantly more diagnostic rises than the CF test in the case of influenza A (222 vs. 162, P less than 0.001) and parainfluenza virus antibodies (29 vs. 16, P less than 0.01). More diagnostic rises in influenza B antibodies were also observed by EIA compared to the CF test (104 vs. 99, not significant). There were only two patients who showed a diagnostic rise in CF antibodies (both influenza B) but not in EIA. Most often patients with a diagnostic antibody rise only by the EIA method had a two-fold rise in the respective CF antibodies (68% of cases). EIA was found to be a sensitive and reliable method for the serological diagnosis of influenza A, B and parainfluenza infections.

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

Summary 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.

Improved sensitivity and specificity of enzyme immunoassays with P1-adhesin enriched antigen to detect acute Mycoplasma pneumoniae infection

An in-house P1-enriched (168-kDA protein) Mycoplasma pneumoniae antigen preparation was compared in IgG, IgA and IgM enzyme immunoassays (EIAs) to the respective EIAs employing crude antigen lysate, antigen prepared by Triton X-114 partition and two commercial antigens, one of which was an ether-extracted antigen and the other a P1-enriched antigen. In addition, three commercial kits from Sanofi Pasteur, Novum Diagnostica and Savyon Diagnostics were also assessed for comparison. Diagnostic sensitivity was studied with paired samples from adults (n=37) with acute respiratory illness interpreted as acute, recent or past infection to M. pneumoniae on the basis of the results of complement fixation test (CFT). If the consensus of at least two methods is taken as the true positive for acute infection, the diagnostic sensitivities of combined IgG and IgM EIAs were 100% for the Platelia(R), Sero MP and in-house EIAs whereas for the Novum EIAs and CFT- 97% and 74%, respectively. Moreover, the sensitivity of the P1-enriched antigen was proven superior on the basis of systematically highest OD(405 nm) ratios between convalescent and acute serum samples. Analytical specificity was studied by screening serum samples from 92 Finnish blood donors and 111 serum samples from cord blood. Diagnostic specificity was studied in a blind testing of 30 paired serum samples from infants with pneumonia of variable etiology. No single misinterpretation of acute infection from the group of samples with other respiratory diseases did occur. The present study confirmed and extended the earlier observations of the usefulness of P1-enriched antigen for reliable serologic diagnosis of acute M. pneumoniae infection.

No evidence of Mycoplasma pneumoniae in acute myringitis.

Our aim was to discover Mycoplasma pneumoniae in bullous and hemorrhagic myringitis in children <2 years of age. Middle ear fluid samples (n = 37) and samples taken from the blisters of the tympanic membranes (n = 12) studied by polymerase chain reaction for M. pneumoniae were negative. This study does not support an important role for M. pneumoniae as an etiologic agent in acute myringitis.