ABSTRACT
Objective To observe the differences between Nested-polymerase chain reaction(N-PCR) and virus isolation methods used for detection of respiratory syncytial virus(RSV),and to reveal the potential clinical features of them.Methods From Jan.2010 to Aug.2012,nasopharyngeal aspirates (NPAs) were collected from the children with respiratory infection in the Department of Respiratory,the Children's Hospital of Chongqing Medical University.Both N-PCR and virus isolation were applied to detect RSV,and clinical data were collected for statistical analysis.Results A total of 1143 specimens were used for RSV detection by N-PCR and virus isolation.The male-female ratio was 2.16 vs 1.00.The age of patients was ranged from 1 month to 165 months(median:7 months).The most common diagnoses were as follows:bronchopneumonia [478 cases (41.8％)],chronic fibrous pneumonia [223 cases (19.5％)],bron-chiolitis [221 cases (19.3％)],bronchitis [71 cases (6.2％)] and upper respiratory infection [21 cases(1.8％)].For N-PCR,458 cases were RSV positive (total positive rate was 40.1％ ; 31.7％ for RSV-A,7.7％ for RSV-B,0.7％ for both RSV-A and RSV-B).With virus isolation method,204 cases were positive (17.8％).Comparison result of N-PCR and virus isolation showed:165 cases were positive (P+ I+) and 646 cases were negative (P-I-) by both methods (identity was 70.1％),and the most difference was N-PCR positive but virus isolation negative group (P+ I-) (293 cases,25.6％).When compared to P-I-group,the clinical features of P+ I-group were as follows:younger,longer hospital stays,remarkable season distribution (with peak in winter and lowest in summer),lower percentage of fever,higher percentage of cough,wheezing,dyspnea,severe pneumonia and respiratory failure,all these differences were statistically significant(all P ＜ 0.05),the ma-nifestations matched the clinical features of RSV infection.When compared to P + I + group,the symptoms in the P + I-group had longer duration before they were admitted to hospital (P =0.005) and lower percentage of wheezing (P =0.009).Conclusions The differences between N-PCR and virus isolation for the detection of RSV existed in duration of symptoms prior to hospitalization.Both the sensibility and specificity of N-PCR are desirable for RSV detection.
ABSTRACT
Objective To explore the causative factors of children with respiratory tract infection and their clinical features.Methods Nasopharyngeal aspirate (NPA) was collected from 1746 children with acute respiratory infections (ARIs),aged from 37 days to 3 years,who were admitted to Children's Hospital of Chongqing Medical University between Jun.2009 and May 2011.Fourteen respiratory viruses in NPA were investigated using polymerase chain reactions (PCR) after nucleic acids extracted from the samples and then synthesized cDNA.Sequence analysis was performed to verify the results of each virus from random positive samples.A total of 23 cases were identified with twice or more admissions to hospital.Individual factors,virus detection and clinical characte-ristics were compared between patients with and without repeated hospitalization.Risk factors for repeated hospitalization were investigated.Then these factors were compared in patients with repeated hospitalization between first time and second time.Results The median age was 7 months in patients with repeated hospitalization and 8 months in patients without repeated hospitalization,there were significantly different difference (P ＜ 0.0001).There was no significant difference in virus detection including influenza type A,parainfluenza,respiratory syncytial virus (RSV),adenovirus and human bocavirus between patients with and without repeated hospitalization in the same age group.By comparing clinical features between patients with and without repeated hospitalizatin in the same age group,(69.6％ vs 47.4％,P =O.037) and diarrhea (52.2％vs 29.0％,P =0.017) were found more often in patients with repeated hospitalization.There was no connection between respiratory virus detection and presence of fever,wheeze,cough and diarrhea in patients with repeated hospitalization for the first time of hospitalization.RSV was the most frequently appeared virus in twice hospitalizations,presenting 52.2％ and 30.4％,respectively.One case had twice positive for RSV.In the first hospitalization,there were 16 viruspositive cases and 16 wheeze cases,while in the second hospitalization,there were 12 virus-positive cases (75.0％)and 11 wheeze cases (68.8％),respectively.Conclusions Children with respiratory tract infections suffered repeated hospitalization,mainly occur in children less than 3 years old.Wheeze is an important clinical feature in children with repeated hospitalization.Although causative viruses for patients in each infection are different,RSV is the most common detected viral agent.Virus-positive cases in the first hospitalization present higher viral detection rate during the second hospitalization,with similar trend for wheeze.