infection control and antibiotic stewardship [5e8]. Hence, ID physicians in China are faced with the challenge of retaining their professional relevancy and must therefore seek to modernize and redefine ID medicine to keep up with changes in healthcare demands. To understand the current working conditions and problems faced by ID physicians and to make recommendations for the development of the specialty in China, a national cross-sectional survey was conducted among hospital ID departments and ID physicians. Materials and methods Survey population A stratified random sampling method was used to select the hospitals and ID physicians. Five tertiary hospitals (i.e. large hospitals that provide health care by specialists to patients referred from primary and secondary care facilities) and five secondary hospitals (i.e. hospitals that support licensed physicians in paediatrics, obstetrics and gynaecology, general surgery and other supporting medical services) in each of the 21 provinces in China were selected. In each tertiary hospital, ten ID physicians were randomly selected: four junior physicians, four attending physicians and two senior physicians. In each secondary hospital, five ID physicians were also randomly selected, including three junior and two attending physicians. Survey instrument The questionnaire was self-designed on the basis of consulting a large amount of literature and had been revised after expert evaluation and a pilot study. The questionnaire sent to institutions consisted of 31 questions in five parts: general information, medical services, education and training, scientific research, and others. The questionnaire sent to ID physicians consisted of 34 questions in five parts: personal information, medical practice, education and training, scientific research, and occupational remuneration and satisfaction (see Supplementary material, Appendix S2). Survey procedure In MayeJune 2016, he Chinese Medical Doctor Association Infection Branch sent emails during 2 weeks to ID department chiefs offive tertiary and five secondary hospitals in each province, inviting them to take part in the study. Questionnaires were subsequently sent to ID department chiefs who agreed to participate, with reminder emails sent 1 week later. The ID department chiefs randomly emailed the individual questionnaires to ten ID physicians in their hospitals. The ID department chiefs were advised to consult with their department members in completing the hospital questionnaire and replied on behalf of the ID departments. It was asked that only ID department chiefs complete the survey for their institution. All questions that participants may have were resolved by telephone discussions with the authors. The completed questionnaires were mailed to the Chinese Medical Doctor Association Infection Branch. Participants took part in the study on a voluntary basis and a real-name registration system. No honorarium was offered. Data processing and statistical analysis The collected questionnaires were reviewed manually; missing responses were corrected and verified by recontacting the respondents. All data were entered into a database, double-checked and locked. All data were analysed by SPSS 20.0 statistical software (SPSS Inc., Chicago, IL, USA). Continuous data were described as median and range or as mean ± standard deviation (SD) according to their distribution. Categorical data were described by percentage. Continuous and categorical data were statistically analysed using ManneWhitney U test and chi-squares tests, respectively. Ethical approval All participants consented to participate. Ethical approval was obtained in the First Affiliated Hospital to School of Medicine of Zhejiang University (396). Results Response rates Of the 300 questionnaires sent to ID departments, 156/300 (52.0%) were returned complete, with answers to all the questions; these qualified for analysis. Response rates were 94/150 (62.7%) for tertiary hospitals and 62/150 (41.3%) for secondary hospitals. Of the 2250 questionnaires distributed to ID physicians, 1071/2250(47.6%) were had responses to all the questions and qualified for analysis. Response rates were 770/1500 (51.3%) for physicians at tertiary