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.

[Hepatitis C virus screening: performances characteristics of a commercial automated chemiluminescent microparticle immunoassay (CMIA-ARCHITECT anti-HCV)]

OBJECTIVES

In spite of improvement of the third-generation enzyme immunoassay (EIA) for screening HCV antibodies, some non-specific reactions persist. With commercialisation of a new chemiluminescence microparticle immunoassay (CMIA), we assessed the specificity of 2 assays providing by Abbott Diagnostics: CMIA-ARCHITECT anti-HCV and MEIA-AxSYM HCV 3.0 for qualitative detection of HCV antibodies in serum sample of patients collected in CHU of Caen.

PATIENTS AND METHODS

Anti-HCV results of 9753 serum samples tested by MEIA-AxSYM V.3 (2004), 6135 tested by CMIA-ARCHITECT1 (April to December 2005) and 5598 tested by CMIA-ARCHITECT2 (February to August 2006) were retrospectively analysed. Prevalences were calculated according to S/C ratio. The serum samples with an average S/C ratio from 1 to 2 for CMIA-ARCHITECT2 were confirmed with an immunoblot assay (Chiron RIBA HCV 3.0 SIA).

RESULTS

The CMIA-ARCHITECT assays showed a strong discrimination between negative and positive samples. We observed a tiny distribution of negative results. The percentage of "low positive" was respectively 1.26% for the MEIA-AxSYM, 0.68% for the CMIA-ARCHITECT1 and 0.36% for the CMIA-ARCHITECT2. Thirty-three of 54 (61%) samples yielding S/C ratio between 1 and 2 in the initial screening analysis with the CMIA-ARCHITECT1 were tested negative with CMIA-ARCHITECT2. Among the 21 remaining, 62% of RIBA results were interpretable.

CONCLUSION

CMIA-ARCHITECT assays improve the anti-HCV screening with a decrease of low-positive reactivity. However, low-positive results persist for which it is difficult to distinguish false-positive from low titer of antibodies. Supplemental assays such as immunoblot can be recommended in particularly context to more improve specificity and HCV-RNA detection should exclude a seroconversion.

Multicentric evaluation of a new commercial cytomegalovirus real-time PCR quantitation assay

Automated real-time PCR systems have become the most common method in the quantitation of viral load during cytomegalovirus (CMV) infection in immuno-compromised patients. In order to evaluate a new commercially available CMV real-time PCR assay (CMV R-gene, Argene, France), a pp65 antigenemia assay and four different "in-house" real-time PCR assays were compared to the CMV R-gene for the detection and the quantitation of CMV load in 506 specimens of whole blood from transplant patients in four French hospital laboratories. The CMV R-gene was more sensitive than the pp65 antigenemia: there were 18% antigenemia-negative versus CMV R-gene-positive samples. A significant correlation was found between DNA quantitation by CMV R-gene and the number of positive cells detected by the pp65 antigenemia test (Spearman's rank test, r=0.63, p<0.0001). A CMV DNA load equivalent to 50 pp65-positive cells/200000 polymorphonuclear leukocytes was 5.26log(10)copies/mL of whole blood. When the CMV R-gene kit was compared to the four other "in-house" real-time PCR assays, there were few discordant results (6.7% total for the four laboratories), all detected with a weak positive CMV DNA viral load. Spearman's coefficients showed a good (r=0.82 for laboratory 1, r=0.66 for laboratory 3) to excellent (r=0.99 for laboratory 2, r=0.94 for laboratory 4) correlation between CMV R-gene and the four real-time "in-house" PCR assays. However, the results of CMV DNA viral load generated by CMV R-gene test were constantly higher than those generated by three out of four "in-house" PCR assays. This mean variation in CMV DNA viral load measured by CMV R-gene and "in-house" PCRs was of 0.77log(10), 0.04log(10), 0.77log(10) and 0.97log(10), for laboratories 1, 2, 3 and 4, respectively. We concluded that there was variability between results of different real-time PCR assays for CMV DNA quantitation. This observation emphasized the need of a standardised commercial assay to allow an "inter-laboratory" comparison of results. Our study showed that CMV R-gene is an accurate, efficient, reliable and versatile tool for rapid diagnosis and monitoring of CMV disease in transplantation recipients.

[Current techniques used for the diagnosis of respiratory virus infectious in intensive care units]

Plusieurs centaines de virus respiratoires différents peuvent être détectés chez les patients atteints d'une infection virale respiratoire et hospitalisés dans un service de réanimation : virus influenza, virus respiratoire syncytial, virus para-influenza, adénovirus, coronavirus, rhinovirus, entérovirus, métapneumovirus humain, bocavirus… La recherche de ces virus doit être effectuée sur un prélèvement nasal ou trachéobronchique, riche en cellules épithéliales. Chez les patients immunodéprimés, il faut ajouter un lavage bronchoalvéolaire pour rechercher le cytomégalovirus et les adénovirus. La mise en évidence d'antigènes viraux par immunofluorescence (IF) ou technique immunoenzymatique dans les cellules infectées est en théorie la méthode la plus simple et rapide à utiliser. Comme pour toutes les techniques de diagnostic, la qualité du prélèvement est un déterminant majeur de son efficacité. Cette méthode est malheureusement peu sensible dans les infections respiratoires chez l'adulte. La recherche virale en culture, compliquée et de réponse tardive, peut être utile dans ce cas en raison de son efficacité. Les méthodes PCR sont plus efficaces : elles peuvent identifier les virus non détectés par les techniques conventionnelles et elles augmentent l'isolement des virus classiques. Elles permettent aussi d'identifier les sous-types viraux, d'étudier par séquençage la variabilité génétique des souches et de quantifier la charge virale respiratoire. Les techniques multiplex recherchant plusieurs virus directement dans les prélèvements sont les plus adaptées au diagnostic en raison du nombre de virus à rechercher. Des méthodes PCR en temps réel, fournissant un résultat rapide, ont été récemment développées. La richesse en cellules et le transport du prélèvement sont moins critiques pour les recherches virales en PCR que pour les techniques conventionnelles d'IF et de culture. De plus, les acides nucléiques persistent plus longtemps que les virus infectieux, permettant ainsi un diagnostic plus tardif. Néanmoins, dans un laboratoire de virologie clinique où la rapidité, le coût modéré et la simplicité des techniques sont des exigences prioritaires, le meilleur choix est d'utiliser séquentiellement l'IF et les PCR multiplex. Le développement des outils de PCR multiplex en temps réel est la priorité majeure du futur.

[Mycoplasma pneumoniae infections: retrospective study in Basse-Normandie, 1997-2005. Epidemiology--diagnostic utility of serology and PCR for a rapid diagnostic]

But de l'étude

L'objectif de cette étude est de décrire l'épidémiologie des infections à Mycoplasma pneumoniae (Mpn) en Basse-Normandie par une analyse rétrospective des résultats sérologiques et PCR, et de valider ces deux outils pour un diagnostic précoce de ces infections.

Patients et méthodes

De 1997 à août 2005, 6156 sérums et 6123 prélèvements respiratoires ont été réalisés chez des patients hospitalisés et analysés pour une recherche d'infection à Mpn, soit par PCR, soit par sérologie Elisa, soit par les deux. Pendant la période épidémique (2004–2005), les résultats de 1489 patients ont été analysés.

Résultats

Sur les neuf années, la séroprévalence moyenne se chiffre à 40,4 % et 525 cas d'infection ont été diagnostiqués par PCR et/ou sérologie, se profilant nettement sous l'aspect de deux pics épidémiques espacés de sept ans. Pendant la période épidémique, la séroprévalence augmente (50,2 %) et l'incidence est de 8,3 %. L'analyse des caractéristiques épidémiologiques des 124 cas diagnostiqués montre : une prédominance chez l'enfant et l'adulte jeune, une fréquence saisonnière estivohivernale, l'existence de co-infection virale. L'analyse des résultats chez 36 patients ayant bénéficié des deux tests diagnostiques, PCR et sérologie, montre une concordance dans seulement 41,7 % des cas.

Conclusion

Les infections à Mpn surviennent sur un mode endémo-épidémique, avec une incidence élevée lors des pics épidémiques, particulièrement chez l'enfant. Nous disposons actuellement d'outils bactériologiques performants permettant de réaliser un diagnostic précoce et fiable. Chez l'enfant, il convient d'associer une sérologie (IgM) et une PCR sur un prélèvement nasopharyngé ; chez l'adulte il faudra privilégier la PCR.

The viral bronchiolites diagnosis in children by PCR multiplex

The aim of the study was to determine the etiology of the viral bronchiolites in children by using direct immunofluorescence test and 3 RT-PCR Multiplex (S.Bellau-Pujol) The study was performed on 122 nasal inspirations collected from 3 weeks-6 month old children hospitalizated in the pediatrics service of CH Rouen. The results were that the majority (53%) of bronchiolites in children had like etiology RSV and a lot of these infections had double viral etiology (26% RSV+ Rhinovirus; 2,7% RSV+HMPV and 1% RSV+Coronavirus 229E). An important viral factor which gives bronchiolitis in children is HMPV (11%). We also find respiratory infections with triple viral etiology: RSV+Influenza A virus + Rhinovirus.

[Fulminant influenza type A associated myocarditis: a fatal case in an 8 year old child]

Fulminant Influenza type A-associated myocarditis are very rare in children. The clinical presentation is non specific, like flu illness, cardiogenic shock or sudden cardiac arrest. We report the case of a eight years old girl with a fulminant Influenza A-associated myocarditis with a fatal evolution despite the use of an extracorporeal membrane oxygenation (ECMO). The aim of this observation is to remind that influenza in children, usually considered as a benign illness, can exceptionally be complicated by a fulminant myocarditis. Because the possibility to recover a full myocardial function, the persistence of severe heart failure despite the medical treatment should conduct rapidly to a mechanical circulatory assistance.

Development and evaluation of a real-time RT-PCR assay on the LightCycler for the rapid detection of enterovirus in cerebrospinal fluid specimens

BACKGROUND

Detection of enteroviral nucleic acid in cerebrospinal fluid (CSF) specimens has been demonstrated to improve the management of patients with aseptic meningitis.

OBJECTIVE

To develop on the LightCycler (LC) instrument a real-time RT-PCR assay based on TaqMan technology for the detection of enteroviruses (EV) in cerebrospinal fluid (CSF) specimens.

STUDY DESIGN

After evaluation of the analytical performances, seventy-four CSF samples collected prospectively from patients who have been suspected for a clinical diagnosis of meningitis were evaluated by two LC real-time RT-PCR assays and one conventional RT-PCR assay.

RESULTS

Our assay detected all 30 different EV species tested, whereas no reactivity was observed with other neurotropic viruses. The analytical sensitivity of both LC RT-PCR real-time assays was 1 TCID50 for LC one-step and two-step RT-PCR assays. Results for LC one-step and LC two-step RT-PCR were compared to results of the conventional RT-PCR: of the 74 CSF specimens tested, 11 were positive and 56 were negative by all methods. Four other specimens were positive for EV by at least two of the methods (including the LC two-step RT-PCR and the conventional RT-PCR), two other CSF specimens were positive by the LC two-step RT-PCR assay only, and another one CSF specimen was positive by the LC one-step RT-PCR assay only. No CSF specimens were negative by the LC two-step RT-PCR assay and positive by the conventional RT-PCR assay. The sensitivity, specificity, positive and negative predictive values of both LC RT-PCR assays by using conventional RT-PCR as the "gold standard" were, respectively, 73.3, 98.3, 91.7, 93.5% for the LC one-step RT-PCR and 100, 96.6, 88.2, 100% for the LC two-step RT-PCR. There was substantial agreement between the three assays (k=0.80).

CONCLUSIONS

The LC two-step RT-PCR assay is a rapid, sensitive and reliable method which can be routinely performed with CSF samples for diagnosis of EV infection and is an important improvement for optimal patient management.

Development and evaluation of Chlamylege, a new commercial test allowing simultaneous detection and identification of Legionella, Chlamydophila pneumoniae, and Mycoplasma pneumoniae in clinical respiratory specimens by multiplex PCR

This study describes the development and evaluation of a new commercial test, Chlamylege (Argene Inc.), which allows the simultaneous detection in respiratory samples of Chlamydophila pneumoniae, Mycoplasma pneumoniae, and most Legionella species, as well as PCR inhibitors, by using a multiplex PCR and microplate hybridization. The sensitivities of Chlamylege were 1 x 10(-3) IFU, 5 x 10(-2) color-changing units, and 1 CFU per reaction tube for C. pneumoniae, M. pneumoniae, and Legionella pneumophila, respectively. A cohort of 154 clinical samples from patients with documented respiratory infections was analyzed by the kit, including 2 samples from patients with C. pneumoniae infection, 9 samples from patients with M. pneumoniae infection, 19 samples from patients with Legionella species infection, and 114 samples that tested negative for the three pathogens. All the positive specimens were correctly detected and identified by the Chlamylege kit, and no false-positive result was observed with the negative samples. The kit was then evaluated in a pediatric prospective study that included 220 endotracheal aspirates, and the results were compared with those obtained by three single in-house PCR assays. Four specimens were found to be positive for C. pneumoniae and six were found to be positive for M. pneumoniae by using both strategies. The Chlamylege kit detected two additional samples positive for M. pneumoniae and one additional sample positive for a Legionella species other than L. pneumophila; these three samples were shown to be true positive by other techniques. These overall results demonstrate that the Chlamylege assay is sensitive, specific, and convenient for the rapid detection and identification of atypical pathogens in clinical samples from patients with respiratory infections.

Development of three multiplex RT-PCR assays for the detection of 12 respiratory RNA viruses

Three multiplex hemi-nested RT-PCR assays were developed to detect simultaneously 12 RNA respiratory viruses: influenza viruses A, B and C, human respiratory syncytial virus (hRSV), human metapneumovirus (hMPV), parainfluenza virus types 1-4 (PIV-1, -2, -3 and -4), human coronavirus OC43 and 229E (HCoV) and rhinovirus (hRV). An internal amplification control was included in one of the RT-PCR assays. The RT-PCR multiplex 1 and the hemi-nested multiplex 1 detected 1 and 0.1 TCID50 of RSV A, respectively, and 0.01 and 0.001 TCID50 of influenza virus A/H3N2, respectively. Two hundred and three nasal aspirates from hospitalised children were retrospectively tested in comparison with two conventional methods: direct immunofluorescence assay and viral isolation technique. Almost all samples (89/91) that were positive by immunofluorescence assay and/or viral isolation technique were detected by the multiplex assay. This method also detected an additional 85 viruses and 33 co-infections. The overall sensitivity (98%), rapidity and enhanced efficiency of these multiplex hemi-nested RT-PCR assays suggest that they would be a significant improvement over conventional methods for the detection of a broad spectrum of respiratory viruses.

[Epidemiology of viral infection and asthma]

The first epidemiological data concerning viruses and asthma were obtained in the 1970s and 1980s by viral isolation and serology. Viral infection can be identified in 24 % to 31.9 % of children, and in 13.3 % of adults. The three most frequent viruses are rhinovirus (RV), respiratory syncytial virus (RSV), and parainfluenza viruses (PIV), detected in 8.8 %, 6.4 % and 6 % of cases, respectively. Due to its amplifying properties, the use of PCR increases the frequency of viral detection, and appears particularly appropriate in asthma where the viral load can be reduced. In a study of bronchiolitis, RSV, PIV3, AdV and RV were identified in 39.3 %, 4.3 %, 1.4 % and 3.9 % of cases, respectively, by IF or culture, and in 62.4 %, 8.3 %, 10.8 % and 12.6 % of cases, respectively, by PCR. Two recent epidemiological surveys used molecular diagnosis in asthma attacks. In a series of 61 adults, 27 (44 %) infections were identified: 16 RV, 4 CV OC43, 3 PIV, 1 RSV, 1 VI, 1 Chlamydia psitacci. In children, viral infection was detected in 226 cases (77 %) : 84 RV, 38 CV, 21 IV, 21 PIV, 12 RSV. We have performed a short retrospective survey for 1997, using molecular biology, on 39 nasal aspirates from children consulting for asthma or wheezing bronchitis. Testing for respiratory viruses by conventional techniques identified 8 (20.5 %) viral infections: 3 RV, 3 RSV, 1 IBV and 1 VPI2. After nucleic acid extraction, PCR-hybridization techniques were applied to these samples to detect RSV, AdV, RV, CV 229E, CV OC43, CP and MP sequences. Twenty six aspirates (54 %) were positive only on molecular biology techniques: 11 RSV, 12 RV, 2 enterovirus, 1 CV OC43. Overall 34 (82 %) viral infections were detected in these children, and a mixed RSV-RV infection was identified in 6 cases. Compared to the studies reported in the literature, we observed the same predominance of RV infections, more RSV infections, probably related to the use of PCR, and a lower incidence of CV infections.

Epidemiology and clinical presentation of respiratory syncytial virus infection in a Tunisian neonatal unit from 2000 to 2002

Respiratory syncytial virus (RSV) is an important viral pathogen causing lower respiratory tract infection (LRI) in infants. This study describes the clinical and genetic epidemiology of RSV infection among Tunisian neonates. Nasopharyngeal aspirates collected from 268 newborns with LRI were screened for RSV by immunofluorescence assay. Positive samples were analysed by RT-PCR-hybridisation assay for subgroup classification of RSV genomes. RSV infection was present in 23.1% of neonates, with a predominance in males. Peak incidence occurred in winter. Subgroup classification showed a higher prevalence of group B than group A strains. Nosocomially acquired RSV infection was present in 37% of neonates, 54.3% had an underlying condition predisposing to severe disease and 13% died. The average duration of hospital stay was 10 days and 87% of newborns required supplemental oxygen. As no currently effective treatment is available, preventive measures are a priority in high-risk infants.

Measles outbreak in the Provence-Alpes-Côte d'Azur region, France, January-July 2003

At the end of May 2003, the Marseilles Hospital Centre's virology laboratory informed the French public heath institute of 5 cases of confirmed measles among young adults living in Marseilles. An investigation was conducted, consulting different community and hospital health services, to determine the virus circulation in the Provence-Alpes-Côte d'Azur (PACA) region by the southern interregional epidemiological cell. The investigation identified 259 cases: 183 clinical, 74 serologically confirmed and 2 epidemiologically linked cases. The first cases were identified during the first six months of 2003, with a peak in April. This outbreak of measles in the PACA region was favoured by poor vaccination coverage, which created groups of susceptible population. The real number of cases was probably higher than the number identified. This investigation has outlined the limitations of the measles surveillance system in France: the sentinel network had not detected any case for this period. France needs to reach the WHO objective of measles elimination by 2010 and the surveillance tools used must be those already used in the most countries that are furthest advanced in the elimination process. To reach this goal, the Direction Générale de la Santé has nominated a working group to be in charge of proposing a national plan to interrupt indigenous measles transmission in France.

Measles outbreak in the Provence - Alpes - Côte d’Azur region, France, January - July 2003

At the end of May 2003, the Marseilles Hospital Centre’s virology laboratory informed the French public heath institute of 5 cases of confirmed measles among young adults living in Marseilles. An investigation was conducted, consulting different community and hospital health services, to determine the virus circulation in the Provence-Alpes-Côte d’Azur (PACA) region by the southern interregional epidemiological cell. The investigation identified 259 cases: 183 clinical, 74 serologically confirmed and 2 epidemiologically linked cases. The first cases were identified during the first six months of 2003, with a peak in April. This outbreak of measles in the PACA region was favoured by poor vaccination coverage, which created groups of susceptible population. The real number of cases was probably higher than the number identified. This investigation has outlined the limitations of the measles surveillance system in France: the sentinel network had not detected any case for this period. France needs to reach the WHO objective of measles elimination by 2010 and the surveillance tools used must be those already used in the most countries that are furthest advanced in the elimination process. To reach this goal, the Direction Générale de la Santé has nominated a working group to be in charge of proposing a national plan to interrupt indigenous measles transmission in France.

[Epidemiology and diagnosis of respiratory syncitial virus in adults]

Introduction

Le virus respiratoire syncytial (VRS) est rarement recherché dans les infections respiratoires de l’adulte. Ce travail en étudie la fréquence et le diagnostic.

Méthodes

Trois enquêtes distinctes ont été menées chez des adultes atteints soit d’un syndrome pseudo-grippal, d’une infection respiratoire basse communautaire ou hospitalisés pour une pneumopathie infectieuse grave. La recherche du VRS a été faite par PCR dans tous les cas et comparée à la détection antigénique et la culture dans deux enquêtes.

Résultats

Le VRS est identifié chez 20 (11,7 %) des 170 adultes vaccinés contre la grippe atteints d’un syndrome pseudo-grippal. Dans 270 infections respiratoires basses communautaires sans signes de gravité on trouve un virus dans 86 (31,8 %) cas, dont 13 VRS (4,8 %) ; un virus est détecté dans 64 (36,7 %) des 164 bronchites aiguës : 11 VRS (6,3 %), 37 rhinovirus (21,3 %), 5 virus influenza A et B, et 12 autres virus ; dans les 60 bronchites chroniques surinfectées, il y a 9 rhinovirus (15 %), 2 virus parainfluenza 3 et aucun VRS ; dans les 21 pneumopathies infectieuses aiguës, on trouve 1 VRS, 1 virus influenza A et 2 rhinovirus, et dans les 11 cas d’infections respiratoires basses sur poumon pathologique, 1 VRS, 1 virus parainfluenza 3 et 4 rhinovirus ; il y a au total 19 infections bactériennes et virales associées. Enfin, dans les 51 pneumopathies infectieuses avec détresse respiratoire hospitalisées en réanimation, un virus est isolé dans 17 (33,3 %) cas : 3 VRS (5,8 %), 6 virus influenza A, 3 rhinovirus, 2 adénovirus, 2 herpes simplex et un CMV ; il y a 6 infections bactériennes associées dont 4 d’origine nosocomiale. Tous les patients infectés par le VRS sont âgés et présentent un facteur de risque respiratoire ou cardiaque.

Conclusions

Chez l’adulte le VRS est responsable de fréquents syndromes pseudo-grippaux et parfois d’infections respiratoires basses, qui peuvent être graves et qu’il faut penser à rechercher. La technique PCR est particulièrement efficace mais non disponible en routine.

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.

Epidemiological and antigenic analysis of respiratory syncytial virus in hospitalised Tunisian children, from 2000 to 2002

Human respiratory syncytial virus (RSV) is the major viral cause of lower respiratory tract disease in children. Infections with the virus occur as annual winter epidemics in temperate climates, placing considerable pressure on the provision of hospital beds. Most molecular epidemiological studies have, until now, focused on isolates from infants in industrialised countries. No data have been available with regard to RSV strains from northern Africa. In this report, a recent RSV outbreak in Tunisia was studied and results showed that 176 of 815 (21.6%) nasopharyngeal aspirates collected from hospitalised children were RSV-positive by immunofluorescence assay. This RSV outbreak showed a temperature-dependent pattern (P=0.026) but no significant association with rainfall. A total of 73 RSV-positive samples were tested by two reverse-transcription-polymerase chain reaction assays (RT-PCR): RT-PCR-1, which amplifies the RNA of all RSV strains, and RT-PCR-2, which allows subgroup classification of RSV. Analysis by hybridisation assay of RT-PCR-2-amplified 1B protein gene products showed a higher prevalence of group B RSV than that of group A (82.5% vs. 17.5% among the typed strains). Knowledge of the variants is important in terms of both diagnosis and definition of a vaccine composition.

Quantitative analysis of HCMV DNA load in whole blood of renal transplant patients using real-time PCR assay

BACKGROUND

Preemptive antiviral treatment of Human Cytomegalovirus (HCMV) disease is a major goal in the management of organ transplant patients. It requires sensitive diagnostic methods. Automated real-time PCR systems have been recently proposed to monitor HCMV infection in such patients.

OBJECTIVE

Objectives of this study was to compare a real-time quantitative PCR on whole blood with the HCMV pp65 antigenemia assay in renal transplant recipients, and also to evaluate two different DNA extraction methods.

STUDY DESIGN

A total of 248 specimens from 21 patients were tested by quantitative pp65 antigenemia and quantitative real-time PCR. DNA was extracted from whole blood samples using two different methods: a conventional column manual assay and an automated system.

RESULTS

Quantification of HCMV DNA using the two extraction methods showed highly similar results (Spearman rank test, r=0.863). We found a significant correlation between DNA quantification by real-time PCR in whole blood and pp65 antigenemia test (Spearman rank test, r=0.767). This correlation was not modified when the HCMV DNA results were normalized by quantification of the albumin cellular gene. In eight patients, HCMV infection was detected earlier with quantitative PCR than with the antigenemia test (mean delay of 11.25 days). HCMV DNA load equivalent of 50 pp65 positive cells/200,000 polymorphonuclear leukocytes (PMNLs) is log4.095 copies per ml of blood.

CONCLUSIONS

Real-time PCR in whole blood is a sensitive method for estimating the HCMV genome load in renal transplant patients, and is more rapid and practicable than using PMNLs for pp65 antigenemia tests.

[Acute respiratory tract infections due to a human metapneumovirus in children: descriptive study and comparison with respiratory syncytial virus infections]

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.