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目的了解中央空调冷却塔气溶胶军团菌污染状况和影响因素,探讨早期预警,研究有效的采集方法。方法于2008年6—8月对马鞍山市13户宾馆、商场、浴场当年使用的中央空调系统进行两轮采样;用液体撞击式微生物气溶胶采样器收集中央空调冷却塔气溶胶,同时采集同一系统的冷却塔、膨胀水箱水样,对67件样品分别用细菌培养法、聚合酶链反应法(PCR)检测军团菌。结果气溶胶军团菌培养阳性率为0,PCR检测阳性率为50.0%,采样容积≥400L和<400L的气溶胶样品检测阳性率分别为90.0%和16.7%,差异有统计学意义(χ2=11.7,P=0.001)。随着冷却塔运行时间的延长,气溶胶含菌阳性率升高,气溶胶检出军团菌组的现场相对湿度高于未检出组(P=0.002)。结论气溶胶军团菌的PCR检测结果阳性,应成为发生、传播军团病的重要的早期预警指征。收集400L以上空气可满足冷却塔气溶胶军团菌的PCR检测,高湿环境可增加军团菌污染气溶胶的风险。
Objective To understand the status and influencing factors of aerosol Legionella contamination in central air conditioning cooling towers and to explore early warning and effective collection methods. Methods From June to August, 2008, the central air-conditioning system used in 13 hotels, shopping malls and bathing beaches in Ma’anshan City was sampled in two rounds. The liquid aerosol sampler was used to collect the aerosol from the central air-conditioning cooling tower and the same system Of the cooling tower, expansion tank water samples, respectively, 67 samples were bacterial culture, polymerase chain reaction (PCR) detection of Legionella. Results The positive rate of Legionella aeruginosa culture was 0, the positive rate of PCR detection was 50.0%, the positive rates of aerosol samples with sampling volume ≥400L and <400L were 90.0% and 16.7%, respectively (χ2 = 11.7 , P = 0.001). With the extension of running time of the cooling tower, the positive rate of aerosol bacteria increased, and the field relative humidity of Legionella aeruginosa group was higher than that of the non-detected group (P = 0.002). Conclusion The result of PCR test of Legionella pneumoniae is positive and should be an important early warning sign of occurrence and spread of Legionnaires’ disease. Collection of more than 400L of air to meet the cooling tower aerosol Legionella PCR test, high humidity environment can increase the risk of Legionella contamination of aerosol.