Riitta Räty

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.

Aetiology of community-acquired pneumonia: Serological results of a paediatric survey

Serological methods are routinely used in the diagnosis of viral and atypical bacterial respiratory infections. Recently, they have also been applied to typical bacteria, such as Streptococcus pneumoniae. The aim of this study was to determine the aetiology of paediatric community-acquired pneumonia (CAP) in both ambulatory and hospitalized patients, by using antibody assays. During a 15-month prospective surveillance, paired sera were studied for antibodies to 14 microbes in 101 children with symptoms of acute infection and infiltrates compatible with pneumonia on chest radiographs. A potential causative agent was detected in 66 (65%) patients. Evidence of bacterial, viral and mixed viral-bacterial infection was demonstrated in 44%, 42% and 20% of the CAP cases, respectively. The most commonly found agents included Mycoplasma pneumoniae (27%), Pneumococcus (18%) and respiratory syncytial virus (17%). Human metapneumovirus (hMPV) was detected in 5 (5%) children. Pneumococcal infections were evenly distributed among the age groups studied. Our results confirm the role of S. pneumoniae in paediatric CAP at all ages, those of M. pneumoniae at >2 y of age and emphasize the emerging role of hMPV. The high proportion of mixed viral-bacterial infections highlights the need to treat all children with CAP with antibiotics.

Pathogenic bacteria and viruses in induced sputum or pharyngeal secretions of adults with stable asthma

Background: Respiratory infections are well known triggers of asthma exacerbations, but their role in stable adult asthma remains unclear. Methods: 103 asthmatics and 30 control subjects were enrolled in the study. Sputum was induced by inhalation of 3% NaCl solution. Oropharyngeal swab specimens were obtained from the posterior wall of the oropharynx. Respiratory specimens were analysed by RT-PCR for rhinovirus, enterovirus and respiratory syncytial virus and by PCR for adenovirus, Chlamydia pneumoniae, Mycoplasma pneumoniae and Bordetella pertussis. Results: Sputum samples from two of the 30 healthy controls (6.7%), five of 53 patients with mild asthma (9.4%), and eight of 50 with moderate asthma (16.0%) were positive for rhinovirus. Rhinovirus positive asthmatic subjects had more asthma symptoms and lower forced expiratory volume in 1 second (FEV1) (79% predicted) than rhinovirus negative cases (93.5% predicted; p = 0.020). Chlamydia pneumoniae PCR was positive in 11 healthy controls (36.6%), 11 mild asthmatics (20.8%), and 11 moderate asthmatics (22%), and PCR positive asthmatics had lower FEV1/FVC than negative cases (78.2% v 80.8%, p = 0.023). Bordetella pertussis PCR was positive in 30 cases: five healthy controls (16.7%), 15 mild asthmatics (28.3%), and 10 moderate asthmatics (20%). Bordetella pertussis positive individuals had lower FEV1/FVC (77.1% v 80.7%, p = 0.012) and more asthma symptoms than B pertussis negative cases. Conclusions: Rhinovirus, C pneumoniae, and B pertussis are found in the sputum or pharyngeal swab specimens of asthmatic subjects without concurrent symptoms of infection or asthma exacerbation, as well as in some healthy controls. Positivity is associated with lower lung function and more frequent asthma symptoms.

Respiratory viruses in laryngeal croup of young children

Objectives To determine the viral cause of laryngeal croup by use of highly sensitive methods, and including recently recognized viruses in the analysis. Study design One hundred forty-four consecutive children with hoarse voice and inspiratory stridor attending the emergency department were enrolled. Age- and season-matched children presenting with a wheezing illness served as control subjects (n = 76). Nasopharyngeal swabs were analyzed by polymerase chain reaction for rhinovirus and enterovirus, coronavirus, respiratory syncytial virus (RSV), parainfluenza virus (PIV), influenza A and B virus, human bocavirus, human metapneumovirus, adenovirus, and Mycoplasma pneumoniae. Results Virus infection was documented in 80% of patients with croup and 71% of control subjects. Children with croup had significantly more positive test results for PIV 1 and 2 (31% vs 4% and 6% vs 0%, respectively) and significantly fewer positive test results for RSV (15% vs 28%) than wheezing children. Rhinoviruses and enteroviruses were present equally in both groups (21% vs 25%). There was no significant difference in the frequency of influenza A virus or human bocavirus. Few subjects with adenovirus or M. pneumoniae were detected. Conclusion Acute laryngeal croup is most often associated with PIV, RSV, rhinovirus, and enterovirus. Rhinovirus and enterovirus appeared equally often in croup and in wheezing illness. During late fall, they were found in 39% and 40%, respectively, of the tested samples.

Detection of antibodies to Mycoplasma pneumoniae adhesin P1 in serum specimens from infected and non-infected subjects by immunoblotting

Paired serum specimens from 17 patients with Mycoplasma pneumoniae infection, as demonstrated by a rise in complement fixation (CF) antibody titer and 14 single sera, negative in the CF test, were tested for the presence of Ig A, Ig G, and Ig M antibodies to a polypeptide with a molecular weight of 170 KDa (P1) in an immunoblot assay. In acute phase sera, collected in the 1st week of the disease, frequency of occurrence of the antibodies against P1 protein did not exceed 18%. Two to three weeks later, Ig A antibodies were detectable in 82.4%, Ig M in 76.5%, and Ig G antibodies in all convalescent phase sera. No sera negative in the CF test (titer < 4) had antibodies against M. pneumoniae adhesin P1.

A filtration method for harvesting Mycoplasma pneumoniae cells

Abstract An easy method for harvesting Mycoplasma pneumoniae ( M.pn. ) cells from batch cultures by a tangential flow filtration device is described. The quality of the resulting cell suspension is monitored by two common serological tests; complement fixation test (CFT) and enzyme-linked immunosorbent assay (EIA). For CFT a lipid extract of the M.pn cell suspension is used as antigen and the remaining lipid-depleted cells are the antigen for EIA. No difference is observed between this lipid antigen and the commercial one when the respective CFT results are compared. The ‘protein antigen’ seems to be sensitive for detecting titer rises between paired sera of patients with an enfectious illness. An additional advantage is that the EIA allows detection of antibodies belonging to different immunoglobulin classes.