目的：了解温州地区儿童急性下呼吸道感染(LRTI)的病原学特点及细菌耐药情况。方法：454例急性LRTI患儿(年龄1个月~10岁,中位年龄6.0个月)入院24h内抽取下呼吸道分泌物送细菌培养,药敏试验采用K-B法,同时应用直接免疫荧光法检测呼吸道病毒。结果：297例(65.4%)病原检测阳性,其中病毒阳性229例(50.4%),以呼吸道合胞病毒(RSV)最多见(39.6%),其次为副流感病毒3型(PIV3)(6.6%)、腺病毒(2.2%)、流感病毒A型(0.9%)及流感病毒B型(0.7%)。共分离出19种135株(29.7%)致病菌,以肺炎克雷伯杆菌(K.pn)最多见(9.9%),其次为大肠杆菌(E.coli)(4.4%),K.pn和E.coli产ESBLs株分别占42.2%和65.0%;肺炎链球菌(SP)占4.2%。混合感染率为14.8%。6个月以下患儿前5位病原为RSV,K.pn,PIV3,E.coli及SA;而RSV,PIV3,SP,K.pn及E.coli则是6个月至3岁患儿常见的病原。K.pn和E.coli对氨苄西林的耐药率分别达97.8%和75.0%,产ESBLs株的K.pn和E.coli对头孢菌素普遍耐药;SP对红霉素的耐药率高达100%,对青霉素的耐药率亦达68.4%,而SA对红霉素和青霉素的耐药率分别为94.7%和89.5%。结论：RSV是温州地区儿童急性LRTI最常见的病原,其次为K.pn和PIV3。常见细菌的抗生素耐药性及革兰阴性杆菌产ESBLs的比率均相当高。

OBJECTIVE: The etiology of acute lower respiratory tract infection (LRTI) in children in Wenzhou City remains poorly defined. This study investigated the etiological agents responsible for acute LRTI and patterns of the antibiotic resistant bacterial pathogens in children with acute LRTI from Wenzhou City. METHODS: Lower respiratory tract secretions were obtained from 454 children with acute LRTI (aged 1 month to 10 years, median age 6 months) within 24 hrs after admission for bacterial culture. Meanwhile respiratory viruses were detected by the Direct immunofluorescence (DIF) assay. The K-B method was applied for the drug susceptibility test. RESULTS: Etiological agents were identified in 297 cases out of 454 patients (65.4%). Viral pathogens were identified in 229 cases (50.4%), bacteria in 135 cases (29.7%) and mixed viral-bacterial infections in 67 cases (14.8%). The isolating rate of Respiratory syncytial virus (RSV) was the highest (180 cases, 39.6%) in all of the samples. The isolating rates of other viral pathogens were as follows: Parainfluenza virus 3 type (PIV3) (6.6%), Adenovirus (2.2%), Influenza A (0.9%) and Influenza B (0.7%) . Of the 135 strains of bacterial pathogens, 19 kinds of bacterial pathogens were isolated. The predominant isolate was Klebsiella pneumoniae (K. pneumoniae) (9.9%), followed by Escherichia coli (E.coli) (4.4%), Streptococcus pneumoniae (S. pneumoniae) (4.2%) and Staphylococcus aureus (S. aureus) (4.2%). The isolating rates of K. pneumoniae and E.coli with extended-spectrum beta-lactamases strains (ESBLs) positive were 42.2% and 65.0%, respectively. The pathogens isolated of the first 5 places in children with acute LRTI under six months were RSV, K. pneumoniae , PIV-3, E.coli and S. aureus in turn. RSV, PIV3, S. pneumoniae, K. pneumoniae and E.coli were found to be the pathogens of the first 5 places in children with acute LRTI between six months and three years. The resistant rates of K. pneumoniae and E.coli to ampicillin were 97.8% and 75.0%, respectively. K. pneumoniae and E.coli with positive ESBLs were resistant to cephalosporin. The resistant rates of S. pneumoniae to erythromycin and penicilin were 100% and 68.4% , respectively. The resistant rates of S. aureus to erythromycin and penicillin were 94.7% and 89.5%, respectively. CONCLUSIONS: RSV is the most common pathogen responsible for acute LRTI in children in Wenzhou City, followed by K. pneumoniae and PIV3. The rate of antibiotic resistance of common bacteria and the isolating rate of Gram-negative bacillus with ESBLs positive are high.