[Human metapneumovirus]. / Métapneumovirus humain.

The human metapneumovirus (hMPV) is a new Pneumovirinae related to the avian metapneumovirus type C. hMPV genome differs from human respiratory syncytial virus (RSV) genome by the gene order and the lack of nonstructural genes. Two genetic sub-groups and four sub-types of hMPV are identified. hMPV infections evolve as regular winter outbreaks which have roughly the same size and overlaping RSV epidemics. Among hospitalized children in Caen, hMPV is detected in 9.7% of the cases after RSV (37%), rhinovirus (18%), influenza virus (14.5%), adenovirus (9%), and parainfluenza virus (5%). Most of hMPV infections are observed in children suffering from bronchiolitis, but the localization to lower respiratory tract and the severity of the disease are less frequent in comparison with RSV infections. hMPV is very difficult to isolate using cell culture. Up to now, the only way for hMPV diagnosis was the TS-CRP assays. But the recent apparition of direct antigenic tests allows us to get a fair, rapid, and economic diagnostic tool.

Etiology of viral pneumopathies in patients in intensive care unit under mechanical ventilation.

The objective of this work was to define the etiology of viral pneumopathies at the patients from reanimation section being under mechanical ventilation, making reference to viruses with respiratory tropism, and also to Chlamydia Pneumoniae and Mycoplasma pneumoniae. The subjects were 36 patients hospitalized into Service of Medical Reanimation from CHU Caen and who needed mechanical ventilation more than 48 hours. The samples from the patients were mostly nasal aspirate, 1 bronchial aspirate and 2 tracheal aspirates. The diagnosis tests were: the test of direct immunofluorescence (DIF) from the samples (for Influenza viruses A and B, Parainfluenza 1,2,3, Adenovirus and Respiratory Syncytial Virus (RSV), inoculation on the tissue culture of diploid cells MRC5, and at the appearance of cythopatic effect specific for Herpes Simplex Virus (HSV), it was made DIF for the detection of type 1 or 2, and also there were made 6 techniques of Polymerase Chain Reaction (PCR). The results of the tests were: at admission before installing the mechanical ventilation, 6 patients presented an infection with Rhinoviruses (RV), 3 with Influenza type A, 3 with HSV type 1 and 2 with Enterovirus. After a period of time from installing the mechanical ventilation, 8 patients presented an infection with HSV typel, among who 1 presented at admission an infection with RV, and 1 patient presented at 7 days from installing the mechanical ventilation an infection with RSV, and at 16 days an infection with HSV type 1. Thus, it could be concluded that in 25% from the cases of viral pneumopathies from patients being under mechanical ventilation it was an endogen reactivation of HSV type1 and only into a single case was diagnosed initially with an infection with RSV, after that it appeared also an infection with HSV typel.

Molecular diversity of the aminoterminal region of the G protein gene of human respiratory syncytial virus subgroup B.

Two major antigenic subgroups (designated A and B) have been described for human respiratory syncytial virus (HRSV). Between and within the two main subgroups, there is antigenic variation in the attachment protein G. The variability of the G protein is known to be located in two hypervariable regions of the ectodomain. Most investigators have studied the gene segment coding the C-terminal end of the protein, and little is known about the N-terminal variable region. In the present study, the genetic variability of HRSV subgroup B was evaluated by nucleotide sequencing of the N-terminal region of the G gene of 52 Tunisian isolates. Tunisian subgroup B isolates clustered into two main lineages designated arbitrarily as Tu-GB1 and Tu-GB2. Three distinct subtypes were identified within genotype Tu-GB2. The inter- and intragenotype nucleotide variability ranged from 4 to 8% and from 0 to 4%, respectively. Overall divergence values of the G sequences were inferior or equal to 15% at the aminoacid level. Comparison of sequences among Tunisian HRSV strains and viruses isolated in other geographical areas during different epidemics demonstrated close similarity to strains from Kenya, Belgium, the UK, Qatar, Canada and South Korea.

[Virology: the contribution of molecular biology in the microbiologic diagnosis of pediatric respiratory diseases]. / Virologie : l'apport de la biologie moléculaire dans le diagnostic microbiologique en pneumopédiatrie.

The conventionnal tools used for virological diagnosis include direct antigen detection by immunofluorescence (IFA) or an immunoenzymatic test (EIA), and viral isolation technique (VIT). In most cases, IFA and EIA have a slightly lower sensitivity than VIT but are also able to detect some VIT-negative samples. Results of several teams using RT-PCR technologies show that the molecular methods detect more positive cases than the conventional tools. Work is under way to expand the number of viruses detected by multiplex RT-PCR and to determine wether newly discovered viruses, such as human metapneumovirus, contribute to burden of paediatric lower respiratory infections. In conclusion, according to requirements of speed, low cost of the methods, and to achieve the highest rate of detection of respiratory viruses, the combined use of IFA and multiplex RT-PCR is today likely to be the best way to improve diagnosis of respiratory illnesses in children.

[Current techniques used for the diagnosis of respiratory virus infectious in intensive care units]. / Techniques actuelles de diagnostic des infections virales respiratoires en réanimation.

Hundred viruses can be isolated in patients suffering from respiratory virus infections and hospitalised in intensive care unit (ICU): influenza virus, respiratory syncytial virus, para-influenza virus, adenovirus, coronavirus, rhinovirus, enterovirus, human metapneumovirus, bocavirus… Nasal or tracheobronchial specimens, which contain many epithelial cells will be used to isolate these common viruses. In immunocompromised patients a bronchoalveolar lavage has to be added to these specimens in order to detect cytomegalovirus and some adenovirus. The immunofluorescence or immunoenzymatic assays, which detect viral antigens in the infected cells are the easiest and fastest diagnostic methods, theoretically. As with other techniques, specimen quality is a major determinant of their performance. Unfortunately, the sensitivity of the antigen detection assays is low in respiratory infections in adults. Then the virus recovery by cell culture, which is usually more sensitive than the antigen detection assays, can be helpful. Many studies have reported more respiratory virus detections using nucleic acid testing such as PCR. They detect viruses, which are missed by conventional methods and increase the detection of common respiratory virus. Multiplex PCR assays have been developed, and these can simultaneously detect several viruses directly in clinical specimens. Nucleic acid testing can subtype viruses using subtype-specific primers, and analyse strain variation through genetic. It can be used also to quantify the viral load in clinical specimens. More recently real-time RT-PCR assays have been developed to get more rapidly the results of the nucleic acids assays. Specimen quality, timing and transportation conditions may be less critical for nucleic acid testing than for culture or antigen detection, as viable virus and intact infected cells need not to be preserved. Moreover, viral nucleic acids are detectable for several days longer into the clinical course than is cultivable virus, potentially allowing a diagnosis to be made in late-presenting patients. However, in a clinical virology laboratory, where the speed, low cost, and high sensitivity of the methods are required, the sequential use of antigen detection tests and multiplex PCR could be the best choice, particularly in the clinical setting of respiratory virus infections in adults hospitalised in ICU. In the future, the development of real-time multiplex PCR is likely to be top-priority.

[Epidemiology and diagnosis of respiratory syncitial virus in adults]. / Epidémiologie et diagnostic des infections à virus respiratoire syncytial de l'adulte.

INTRODUCTION: Respiratory syncytial virus (RSV) is rarely searched for in respiratory infections in adults. This study assessed its frequency and diagnosis. METHODS: Three separate studies were conducted in adults presenting with (1) a flu-like illness, (2) a lower respiratory tract infection in the community, and (3) a severe pneumonia requiring hospitalisation. The diagnosis of RSV infection was sought by PCR in all cases, and compared to antigen detection and culture in two studies. RESULTS: RSV was identified in 20 (11.7%) of 170 influenza-vaccinated adults suffering from flu-like symptoms. In the 270 cases of non-severe lower respiratory tract illnesses in the community, viruses were identified in 86 (31.8%) cases, with RSV accounting for 13 (4.8%). In the 164 cases of acute bronchitis, a virus was detected in 64 (36.7%) of which 11 (6.3%) were RSV, 37 (21.3%) rhinovirus, 5 influenza viruses A and B, and 12 other viruses. In the 60 cases of infective exacerbations of chronic bronchitis, rhinovirus was detected in 9 (15%) and para-influenza 3 virus in 2 cases. In the 21 acute pneumonia's, 1 RSV, 1 influenza virus A and 2 rhinovirus cases were detected as well as 1 RSV, 1 parainfluenza 3 viruses and 4 rhinovirus cases in the 11 lower respiratory tract illnesses in patients with pre-existing lung disease. There were overall 19 viral and bacterial associated infections. Finally, in the 51 acute pneumonias hospitalised with respiratory distress syndrome, a virus was identified in 17 (33.3%) cases, including 3 (5.5%) RSV, 6 influenza A, 3 rhinovirus, 2 adenovirus, 2 herpes simplex virus and 1 cytomegalovirus. There were 6 bacterial-associated infections, and 4 were hospital-acquired. All RSV-infected patients were old people and had chronic pulmonary or cardiac disease. CONCLUSIONS: In adults, RSV is a frequent cause of flu-like symptoms. It can sometimes cause lower respiratory tract illness, which can be severe, and should be considered in the differential diagnosis in such cases. The PCR method is a particularly effective diagnostic test, but as yet is not routinely available.

[Acute respiratory tract infections due to a human metapneumovirus in children: descriptive study and comparison with respiratory syncytial virus infections]. / Infections respiratoires aiguës à métapneumovirus humain chez l'enfant: études descriptive et comparative avec le virus respiratoire syncytial.

BACKGROUND: A new paramyxovirus, the human metapneumovirus was recently isolated. We report the first French cases collected between 2000 and 2002. MATERIAL AND METHODS: Samples were obtained from nasopharyngeal aspirates from children hospitalised for acute respiratory tract infection in hospitals of Caen and Flers in Basse-Normandie. Human metapneumovirus was studied by polymerase chain reaction on negative samples for respiratory syncytial virus, influenza A and B virus, parainfluenza (1, 2 and 3) virus, adenovirus, coronavirus and rhinovirus. Comparison between metapneumovirus virus and respiratory syncytial virus infections was done after matching sex, age and infection month. RESULTS: Twenty-six human metapneumovirus infections were identified. A comparative study of a matched group of children infected by respiratory syncytial virus found no significative difference for hospitalisation motive, clinical criteria and treatment. CONCLUSION: The human metapneumovirus is responsible for typical acute bronchiolitis in children.

[Adenoviral respiratory diseases in healthy children: a study of 116 hospital cases]. / Prise en charge des pathologies respiratoires à adénovirus chez l'enfant immunocompétent: À propos d'une étude rétrospective de 116 enfants hospitalisés.

Adenoviruses most commonly cause respiratory illness; however, depending on the infecting serotype, they may also cause various other diseases. Diagnosis may be difficult to achieve.The clinical findings for 116 children hospitalised with adenoviral infection were studied retrospectively. In 71 children, the diagnosis was based on detection of adenovirus antigen in the nasopharyngeal specimens and in 71 children on viral culture. The clinical picture of adenoviral infection was characterised by high-grade (mean 39°1C) and prolonged fever (mean duration 4,3 days). Upper respiratory and lower respiratory symptoms were the most common infections. Twelve had been admitted to the hospital due to febrile convulsions, 6 had meningitis. Laboratory findings varied from normal values to values seen in bacterial infections. Thus it was difficult to distinguish adenoviral disease from a bacterial disease. Fifty-nine children were referred to the hospital due to infection unresponsive to antimicrobial therapy.Symptoms of respiratory infection caused by adenovirus may range from the common cold syndrome to pneumonia, croup and bronchiolitis. Adenoviruses can be responsible for severe consequences, even in previously healthy children. Studies of the molecular mechanisms of viral infections of the airways could provide important insights into the nature of the inflammatory process involved in asthma and chronic obstructive pulmonary disease. Most infections are mild and require no therapy or only symptomatic treatment. There are at present time no recognised antiviral agents that are effective in treating serious adenovirus disease. The rapid detection of adenovirus antigen in nasopharygeal specimens proved to have a great clinical value in the diagnosis.

Comparison of the quick view influenza test (Quidel) to an immunofluorescence assay for the detection of influenza virus infections.

The performancs of a membrane-based EIA, the Quick Vue Influenza test, (Quidel,USA) were compared to those of an immunofluorescence assay (IFA) for the detection of influenza virus A antigens in respiratory samples from children hospitalized during the 2002-2003 winter season. A prospective study was carried out on 2 nasal swabs drawn in parallel from 33 children: 13 samples were positive and 18 negative on both the Quick Vue test and IFA. Using an in-house reverse transcription (RT)- PCR assay as a gold standard, the two discordant results were identified as a false-positive reaction of the IFA and a false-negative one of the Quick Vue test . The sensitivity, specificity, positive and negative predictive values of the Quick Vue test were 87.5%, 100%, 100% and 89.5%, respectively. In the retrospective study of frozen samples, 57 of the 70 positive samples were detected by the Quick Vue test and 5 of 50 negative samples. Using the RT-PCR as a gold standard, there were 4 false-negative and 3 false-positive results on IFA and 10 false-negative results on the Quick Vue test. Our study suggests that performances of the Quick Vue are good if the test is carried out directly on nasal secretions, but that they can be decreased when nasal aspirates are collected in transport medium and frozen.

[Rhinovirus and acute respiratory infections in hospitalized children. Retrospective study 1998-2000]. / Rhinovirus et infections respiratoires aiguës de l'enfant hospitalisé. Etude rétrospective de 1998 à 2000.

OBJECTIVES: Rhinoviruses are the most common aetiological agents of colds, but the frequency and the severity of other locations of the infection are not well known. This study describes the clinical aspects and the severity of rhinovirus infections in hospitalised children. METHODS: Isolation in culture and a RT-PCR were performed for the detection of rhinovirus in nasal aspirates from hospitalised children from September 1998 to October 2000. A group of 211 children found to be positive for rhinovirus was studied. RESULTS: Rhinovirus-infected children suffered from the following clinical syndromes: 60 (28.4%) upper airway infections, 81 (38.4%) bronchiolitis, 25 (11.9%) pneumonias and 12 (4.7%) acute attacks of asthma. Clinical symptoms were wheezing (32%), ronchi (37%) and 29% of children presented with acute distress respiratory syndrome; 40% of the available chest X-Ray were abnormal. Eight children were hospitalised in the intensive care unit and two children died. Twenty-five children (10.9%) had a nosocomial infection; a dual infection was observed in 19 cases (9%) with the following viruses: RSV (3), influenza (2) parainfluenza (8), adenovirus (2), enterovirus (4); 19 (9%) children had a secondary bacterial infection. Rhinoviruses were detected in nasal aspirates in 112 cases (53%) according to the culture and in the rhinovirus culture-negative samples in 99 cases (47%) according to the RT-PCR assay. CONCLUSION: After eliminating cases of bacterial or viral dual infections, the clinical aspects of rhinovirus infections in children are the following: upper respiratory tract infections (25.6%), bronchiolitis ou bronchitis (25.6%), pneumonia (6.2%), acute attack of asthma (5.7%). The virological diagnosis according to culture is mainly improved by molecular techniques.

Evaluation of four commercial immunoglobulin G (IgG)- and IgM-specific enzyme immunoassays for diagnosis of Mycoplasma pneumoniae infections.

The four following commercially available enzyme immunoassays (EIAs) were assessed and compared for their performance in detecting Mycoplasma pneumoniae immunoglobulin G (IgG)- and IgM-specific antibodies Platelia EIA, ImmunoWELL M. pneumoniae ELISA IgG and IgM, ETI-MP-IgG and IgM EIAs and Biotest anti-M. pneumoniae IgG and IgM ELISA (referred to herein as EIA-Platelia, EIA-BMD, EIA-Sorin, and EIA-Biotest). Three groups of patients were investigated: 39 patients (27 children and 12 adults) with respiratory infections who tested positive by PCR for M. pneumoniae in respiratory specimens (group I; 52 serum samples), 61 healthy children and adults (group II; 61 serum samples), and 20 patients with rheumatoid factor or antinuclear antibodies, or who tested positive for antiviral IgM (group III; 20 serum samples). In group III, the IgM specificity for EIA-Platelia, EIA-BMD, EIA-Biotest, and EIA-Sorin was 100, 90, 65, and 25%, respectively. In the children from group I, the four EIAs had similar IgM sensitivities (89 to 92%); the sensitivity for IgG was greater with EIA-BMD and EIA-Biotest than with EIA-Platelia and EIA-Sorin (66 and 78% versus 55 and 52%, respectively). In adult patients from group I, 9 to 10 serum samples were positive for IgG with a concordant sensitivity of 75 to 83% between the four EIAs but a striking difference in IgM sensitivity: 16% by EIA-Platelia and EIA-BMD, 50% by EIA-Biotest, and 58% by EIA-Sorin. Discrepant and unexpected results were observed in IgM detection from control healthy patients using EIA-Sorin and EIA-Biotest, confirming the lack of specificity of these two EIAs and making them inaccurate for routine diagnosis. A good concordance of IgG seroprevalence in healthy adults was found between the four EIAs (66 to 70%), though this concordance was lower with EIA-Platelia (43%). In healthy children, EIA-BMD and EIA-Biotest gave a higher IgG seroprevalence than EIA-Sorin and EIA-Platelia (45% each for the former compared to 17 and 20%, respectively, for the latter). These results confirm that the IgM EIA serology test is a valuable tool for the early diagnosis of M. pneumoniae infections in children, as long as the EIA used is specific. In adults, the difficult interpretation of EIAs suggests that paired sera, combined with PCR detection on respiratory tract specimens collected on admission of patient, should be required for accurate diagnosis.

[Epidemiology of respiratory virus infections]. / Epidémiologie des infections virales respiratoires.

Respiratory viral infections are very common in young children. They sometimes occur as primary infections (and sometimes re-infections) by influenza and parainfluenza virus, respiratory syncytial virus (VRS), adenovirus, rhinovirus and coronavirus. The clinical pictures are very varied and without strict clinico-virological correlation. In adults the role of the site (frail lung, aged persons) and the type of virus play an important part. Many viral infections develop in an epidemiological way (influenza, VRS bronchiolitis, rhinovirus infections...) and several epidemics by different viruses overlap from September-October to March-April making it very difficult to decide the precise cause. Epidemics are followed thanks to networks of medical practitioners (GROG, SENTINELLE...) and by data from hospitalised patients, but precise identification of epidemic viruses is only possible and validated by virological analysis of samples taken from patients.

Early diagnosis of adenovirus infection and treatment with cidofovir after bone marrow transplantation in children.

Adenovirus infection remains an important cause of mortality after bone marrow transplantation (BMT). Currently no efficient antiviral treatment is known. Thus, testing new modalities of early diagnosis and treatment is a crucial objective. Adenovirus infection is defined by the combination of symptoms and the isolation of virus from the source of clinical symptoms. The involvement of two or more organs and the presence of virus in blood cultures define disseminated disease. Seven children with a median age of 7 years received bone marrow transplantation for leukemia. All received an unrelated graft without T cell depletion. Adenovirus was sought in blood, urine and biopsy specimens using PCR and culture. Analysis of biopsy specimens included systematic immunohistochemistry. Cidofovir treatment was initiated as soon as biopsy revealed the histopathological signs of adenovirus. Cidofovir was given at 5 mg/kg once weekly for 3 weeks then every 2 weeks. Six patients had diarrhoea and one patient had cystitis. Adenovirus infection and disseminated disease were diagnosed in four cases and three cases, respectively. In six cases, serotype A31 was isolated from gastrointestinal biopsy and in two cases serotypes B2 and C6 were detected in blood and urine. Cidofovir treatment was associated with clinical improvement of diarrhoea, cystitis and fever in five patients, in whom the virus became undetectable in cultures and PCR analyses despite the persistence of immunodeficiency. The median follow-up was 360 days after BMT (240-570). One child died of invasive aspergillosis and another of disseminated adenovirus after interruption of cidofovir therapy. Further studies in immunocompromised patients will be needed to extend these promising results concerning the role of cidofovir in adenovirus infection.

Multicenter evaluation of a rapid and convenient method for determination of cytomegalovirus immunoglobulin G avidity.

An easy, rapid, and reproducible test to distinguish residual cytomegalovirus (CMV) immunoglobulin M (IgM) antibodies from antibodies produced in primary infection could be useful, especially for pregnant women. The CMV avidity of IgG antibodies with the VIDAS automated enzyme-linked fluorescent assay and 6 M urea was evaluated in a multicenter study to differentiate between primary CMV infections and past infections or reactivations. A total of 416 serum specimens were tested: 159 specimens were from follow-up of primary infections, and 257 were from past infections. All of the specimens from primary infections collected within 4 months (17 weeks) after the onset of the infection had an avidity index lower than 0.8. An avidity index higher than 0.8 excludes a recent primary infection of less than 4 months. However, an avidity index higher than 0.8 cannot confirm all past infections, since 48 specimens (18%) from past infections had an avidity index lower than 0.8 (between 0.5 and 0.8). The exclusion capacity could be improved (96.9%) by using a cutoff of 0.7, but this index would decrease the specificity of the technique, since the avidity index was found to be between 0.7 and 0.8 in two patients with recent primary infection. All specimens from primary infections obtained more than 4 months after the onset of infection had an avidity index more than 0.2. In this study, an avidity index less than 0.2 confirms the presence of a recent primary infection of less than 4 months. The VIDAS CMV IgG avidity test is a rapid, reproducible test with very good performance.

[Viral co-infections in immunocompetent infants with bronchiolitis: prospective epidemiologic study]. / Co-infections virales lors des bronchiolites du nourrisson immunocompétent: étude prospective épidémiologique.

The nature of viral infection was prospectively investigated in 202 immunocompetent infants with bronchiolitis. Nasal aspirates were evaluated by immunofluorescence assay, viral isolation technique and polymerase-chain-reaction-hybridization assay. In 55 infants (27%) more than one respiratory virus were detected. A Rotavirus was found in 40 infants (20%), without any relationship with the respiratory viral status, respiratory syncytial virus being the main virus (46/55), and the association of respiratory syncytial virus and adenovirus being the most frequent (21/55). No difference was found between monoviral infections on the one hand and simultaneous viral infections on the other hand according to age, weight, neonatal disease, past history of personal or familial atopy, central temperature, Silverman's index, oxygen dependency, length of hospitalization, microbiology data. There was no indication that simultaneous virus infections were associated with an increased severity of the bronchiolitis in immunocompetent infants.

Detection of viral, Chlamydia pneumoniae and Mycoplasma pneumoniae infections in exacerbations of asthma in children.

BACKGROUND: A high frequency of virus infections has been recently pointed out in the exacerbations of asthma in children. OBJECTIVES: To confirm this, using conventional and molecular detection methods, and expanding the study to younger children. STUDY DESIGN: One hundred and thirty-two nasal aspirates from 75 children hospitalized for a severe attack of asthma were studied (32 infants, mean age 9.1 months; and 43 children, mean age 5.6 years). According to the virus, a viral isolation technique, immunofluorescence assays (IFA) or both were used for the detection of rhinovirus, enterovirus, respiratory syncytial (RS) virus, adenovirus, coronavirus 229E, influenza and parainfluenza virus. Polymerase chain reaction (PCR) assays were used for the detection of rhinovirus, enterovirus, RS virus, adenovirus, coronavirus 229E and OC43, Chlamydia pneumoniae and Mycoplasma pneumoniae. RESULTS: Using IFA and viral isolation techniques, viruses were detected in 33.3% of cases, and by PCR techniques, nucleic acid sequences of virus, Chlamydia pneumoniae and Mycoplasma pneumoniae were obtained in 71.9% of cases. The combination of conventional and molecular techniques detects 81.8% of positive samples. Two organisms were identified in the same nasal sample in 20.4% of the cases. The percentage of detections was higher (85.9%) in the younger group than in the other (77%). The most frequently detected agents were rhinovirus (46.9%) and RS virus (21.2%). Using PCR rather than conventional techniques, the detection rates were increased 5.8- and 1.6-fold in rhinovirus and RS virus infections, respectively. The detection levels of the other organisms are as follows: 9.8, 5.1, 4.5, 4.5, 4.5, 3.7, and 2.2% for enterovirus, influenza virus, Chlamydia pneumoniae, adenovirus, coronavirus, parainfluenza virus, and Mycoplasma pneumoniae, respectively. CONCLUSION: These results confirm the previously reported high frequency of rhinovirus detection in asthmatic exacerbations in children. They also point out the frequency of RS virus detection, and emphasize the fact that PCR assays may be necessary to diagnose respiratory infections in asthma.

Comparison of two serological methods and a polymerase chain reaction-enzyme immunoassay for the diagnosis of acute respiratory infections with Chlamydia pneumoniae in adults.

Chlamydia pneumoniae is a common respiratory tract pathogen. Serological methods currently used for the diagnosis of C. pneumoniae infection lack specificity, give ambiguous results from a single serum sample and often provide only a retrospective diagnosis. A prospective study was undertaken to assess whether PCR could be a useful addition to the serological techniques routinely practised for diagnosis. This study investigated 68 adult patients with a diagnosis of acute respiratory infection. Acute and convalescent serological determination of antibodies to C. pneumoniae were performed by means of an rELISA test and a micro-immunofluorescence (MIF) test. Nasopharyngeal aspirates or bronchoalveolar lavage specimens and bronchial aspirates obtained from the 68 patients were evaluated by PCR-enzyme immunoassay (PCR-EIA) for the presence of C. pneumoniae and by immunofluorescence assay and cell culture for virus identification. Mycoplasma pneumoniae serology was also performed. Eight patients (11.8%) were positive by either rELISA or PCR-EIA, or both, with an infection rate of 5 (18.5%) of 27 in patients with community-acquired pneumonia, 2 (9%) of 22 in asthmatic patients and 1 (5%) of 19 in patients with an exacerbation of chronic obstructive pulmonary disease. Serological evidence of acute infection was found in four of these patients with the rELISA test and in three others with the MIF test. PCR-EIA detected C. pneumoniae DNA in four specimens, but there were concordant results with both rELISA and PCR-EIA in only one patient A positive PCR-EIA was also obtained in a patient who did not show an antibody response in acute serum. The discrepancy between serological and PCR-EIA results reflects the difficulties in routine laboratory diagnosis of C. pneumoniae infection and the necessity for further studies with optimised techniques.

[Etiology and diagnostic of viral bronchopneumonias]. / Etiologie et diagnostic des bronchopneumopathies virales.

Community viral bronchopneumonias are frequent, mainly in children, and can be associated to all respiratory viruses: influenza- and parainfluenzavirus, respiratory syncytial virus, adenovirus, rhinovirus. The diagnostic method which proves viral infection of the respiratory tissues is selected as the direct detection by an immunofluorescence assay of viral infected cells in respiratory samples. In them, viral isolation or nucleic acid detection by PCR provide an amplification of the viruses. By using PCR-hybridation techniques viral detection is overall increased of 1.5 times for respiratory syncytial virus, 1.9 for parainfluenzavirus 3, 4 for rhinovirus and 10 times for adenovirus. This increased sensitivity raises questions about the meaning of the detection of viral sequences in nasal aspirates, with or without clinical signs. Cytomegalovirus (CMV) is a major agent of pneumonia in immunocompromised patients. All virological markers of CMV infection have to be sought (antigenemia, viremia...), but specific inclusions in pulmonary cells are the single diagnosis criteria. As pulmonary biopsies are rarely available and CMV inclusions rarely found in BAL, it has been reported useful to look for high viral loads or late m-RMA transcripts in these samples. Adenovirus pneumonia are unfrequent in these patients and mostly associated to rare or atypical strains. Such PCR-hybridization systems deserves also to be used in these cases.