Pagani Leonardo, Thomas Yves, Huttner Benedikt, Sauvan Valérie, Notaridis Grigorios, Kaiser Laurent, Iten Anne, Pittet Didier, Harbarth Stephan
Infectious Diseases Unit, Bolzano Central Hospital, Bolzano, Italy; Infection Control Program, University of Geneva Hospitals and Faculty of Medicine, Geneva, Switzerland.
J Am Geriatr Soc. 2015 Apr;63(4):739-44. doi: 10.1111/jgs.13339.
To investigate a nosocomial outbreak of influenza.
Prospective outbreak investigation with active case finding and molecular typing.
A large academic geriatric hospital in Switzerland.
Elderly hospitalized adults.
Based on syndromic surveillance, a nosocomial influenza outbreak was suspected in February 2012. All suspected cases were screened for respiratory viruses using real-time reverse transcription polymerase chain reaction of nasopharyngeal swabs. Infection control procedures (droplet precautions with single room isolation whenever possible) were implemented for all suspected or confirmed cases. Specimens positive for influenza viruses were processed and sequenced whenever possible to track transmission dynamics.
Respiratory samples from 155 suspected cases were analyzed during the outbreak period, of which 69 (44%) were positive for influenza virus, 26 (17%) were positive for other respiratory viruses, and 60 (39%) were negative. Three other cases fulfilled clinical criteria for influenza infection but were not sampled, and one individual was admitted with an already positive test, resulting in a total of 73 influenza cases, of which 62 (85%) were classified as nosocomial. Five distinct clusters of nosocomial transmission were identified using viral sequencing, with epidemiologically unexpected in-hospital transmission dynamics. Seven of 23 patients who experienced influenza complications died. Sixteen healthcare workers experienced an influenza-like illness (overall vaccination rate, 36%).
Nosocomial influenza transmission caused more secondary cases than repeated community importation during this polyclonal outbreak. Molecular tools revealed complex transmission dynamics. Low healthcare worker vaccination rates and gaps in recommended infection control procedures are likely to have contributed to nosocomial spread of influenza, which remains a potentially life-threatening disease in elderly adults.
调查医院内流感暴发情况。
采用主动病例发现和分子分型的前瞻性暴发调查。
瑞士一家大型学术性老年医院。
老年住院成人。
基于症状监测，2012年2月怀疑发生医院内流感暴发。对所有疑似病例使用鼻咽拭子实时逆转录聚合酶链反应筛查呼吸道病毒。对所有疑似或确诊病例实施感染控制措施（尽可能采取飞沫隔离并单间隔离）。对流感病毒阳性的标本尽可能进行处理和测序，以追踪传播动态。
暴发期间对155例疑似病例的呼吸道样本进行了分析，其中69例（44%）流感病毒阳性，26例（17%）其他呼吸道病毒阳性，60例（39%）阴性。另外3例符合流感感染临床标准但未采样，1例入院时检测已呈阳性，因此共有73例流感病例，其中62例（85%）为医院内感染。通过病毒测序确定了5个不同的医院内传播集群，其医院内传播动态在流行病学上出乎意料。23例发生流感并发症的患者中有7例死亡。16名医护人员出现流感样疾病（总体疫苗接种率为36%）。
在这次多克隆暴发期间，医院内流感传播导致的二代病例多于反复的社区输入病例。分子工具揭示了复杂的传播动态。医护人员疫苗接种率低以及推荐的感染控制措施存在漏洞可能导致了流感在医院内传播，而流感在老年人中仍然是一种潜在的危及生命的疾病。
