Contact patterns and microbiological data contribute to a detailed understanding of infectious disease transmission. We explored the automated collection of high-resolution contact data by wearable sensors combined with virological data to investigate influenza transmission among patients and healthcare workers in a geriatric unit.

Proof-of-concept observational study. Detailed information on contact patterns were collected by wearable sensors over 12 days. Systematic nasopharyngeal swabs were taken, analyzed for influenza A and B viruses by real-time polymerase chain reaction, and cultured for phylogenetic analysis.

An acute-care geriatric unit in a tertiary care hospital.

Patients, nurses, and medical doctors.

A total of 18,765 contacts were recorded among 37 patients, 32 nurses, and 15 medical doctors. Most contacts occurred between nurses or between a nurse and a patient. Fifteen individuals had influenza A (H3N2). Among these, 11 study participants were positive at the beginning of the study or at admission, and 3 patients and 1 nurse acquired laboratory-confirmed influenza during the study. Infectious medical doctors and nurses were identified as potential sources of hospital-acquired influenza (HA-Flu) for patients, and infectious patients were identified as likely sources for nurses. Only 1 potential transmission between nurses was observed.

Combining high-resolution contact data and virological data allowed us to identify a potential transmission route in each possible case of HA-Flu. This promising method should be applied for longer periods in larger populations, with more complete use of phylogenetic analyses, for a better understanding of influenza transmission dynamics in a hospital setting.

Infect Control Hosp Epidemiol 2015;00(0): 1–7

The strength of the association between intensive care unit (ICU)-acquired nosocomial infections (NIs) and mortality might differ according to the methodological approach taken.

TO assess the association between ICU-acquired NIs and mortality using the concept of population-attributable fraction (PAF) for patient deaths caused by ICU-acquired NIs in a large cohort of critically ill patients.

Eleven ICUs of a French university hospital.

We analyzed surveillance data on ICU-acquired NIs collected prospectively during the period from 1995 through 2003. The primary outcome was mortality from ICU-acquired NI stratified by site of infection. A matched-pair, case-control study was performed. Each patient who died before ICU discharge was defined as a case patient, and each patient who survived to ICU discharge was denned as a control patient. The PAF was calculated after adjustment for confounders by use of conditional logistic regression analysis.

Among 8,068 ICU patients, a total of 1,725 deceased patients were successfully matched with 1,725 control Patients. The adjusted PAF due to ICU-acquired NI for patients who died before ICU discharge was 14.6% (95% confidence interval [CI], 14.4%—14.8%). Stratified by the type of infection, the PAF was 6.1% (95% CI, 5.7%–6.5%) for pulmonary infection, 3.2% (95% CI, 2.8%–3.5%) for central venous catheter infection, 1.7% (95% CI, 0.9%–2.5%) for bloodstream infection, and 0.0% (95% CI, –0.4% to 0.4%) for urinary tract infection.

ICU-acquired NI had an important effect on mortality. However, the statistical association between ICU-acquired NI and mortality tended to be less pronounced in findings based on the PAF than in study findings based on estimates of relative risk. Therefore, the choice of methods does matter when the burden of NI needs to be assessed.

To measure the incidence of nosocomial infection (NI) among patients with septic shock according to the place of septic shock acquisition and to evaluate the increase in the risk of pulmonary infection associated with septic shock.

Prospective cohort study.

TWO intensive care units (ICUs) of a French university hospital.

The study included a total of 209 septic shock patients during the period December 1, 2001 through April 30, 2005. The place of septic shock acquisition for 108 patients was the community; for 87, the hospital; and for 14, the ICU. To evaluate the impact of septic shock on the development of pulmonary infection, a competitive and adjusted hazard ratio (aHR) model was applied to nontrauma ICU patients.

Among the 209 study patients, 48 (23%) experienced 66 NIs after septic shock. There was no significant difference in the NI attack rates according to place of acquisition: for the community acquisition group, 24 cases per 100 patients (95% confidence interval [CI], 16-32); for the hospital acquisition group, 20 cases per 100 patients (95% CI, 11-28); and for the ICU acquisition group, 36 cases per 100 patients (95% CI, 11-61) (P = .3). For nontrauma ICU patients, the presence of community-acquired septic shock was found to be independently associated with a higher incidence of pulmonary infection, compared with the absence of septic shock (aHR, 2.12 [95% CI, 1.08-4.16]; P = .03).

The risk of NI did not differ by the place of septic shock acquisition. The risk of pulmonary infection was higher for ICU patients with community-acquired septic shock who were admitted for underlying nontrauma disease. Studies are needed to investigate the pathogenic mechanisms that facilitate pulmonary infection in this population, taking into account exposure to invasive devices and immunosuppression after the initial phase of septic shock.