Multi-level analysis of bacteria isolated from inpatients in respiratory departments in China

Background: With the different situation for clinical antibiotic usage and its management in different regions and medical institutions, the antimicrobial resistance varied in different level. However, the epidemiological data of multi-drug resistant (MDR) strains from the department of respiration is limited. Thus, this study aims to investigate the epidemiology of bacteria isolated from inpatients of respiratory departments, and analyze the distribution variation of major multi-drug resistant bacteria in China. Methods: Based on data from China Antimicrobial Resistance Surveillance System (CARSS) in 2015, 50,417 non-duplicate isolates obtained from inpatients of respiratory departments from 91 general hospitals in seven regions of China were enrolled in the study. The distribution of methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Escherichia coli (CREC) and Klebsiella pneumoniae (CRKP), carbapenem-resistant Pseudomonas aeruginosa (CRPA) and Acinetobacter baumannii (CRAB), extended-spectrum beta-lactamases-producing E. coli (ESBL-EC) and K. pneumoniae (ESBL-KP), were further analyzed by geographic regions, age groups, wards and specimen types. Results: The major specimens type were sputum (81.6%, 41,131/50,417), followed by blood (5.3%, 2,649/50,417), urine (4.5%, 2,249/50,417) and bronchoalveolar lavage fluid (BALF) (3.2%, 1,620/50,417). The top four bacteria species isolated from sputum and BALF were similar: K. pneumonia (18.9% and 14.8%, respectively), P. aeruginosa (13.6% and 22.2%, respectively), A. baumannii (11.3% and 11.9%, respectively) and S. pneumonia (11.1% and 9.6%, respectively). The four most common bacteria species were K. pneumonia (17.2%), P. aeruginosa (12.1%), A. baumannii (10.4%) and S. pneumonia (10.1%) in tertiary hospitals but K. pneumonia (20.8%), P. aeruginosa (16.3%), E. coli (11.3%) and A. baumannii (6.9%) in secondary hospitals. The top four bacteria species in respiratory intensive care unit (RICU) were A. baumannii (25.8%), P. aeruginosa (13.1%), K. pneumonia (12.2%) and S. aureus (9.2%). The prevalence of CRKP, CRPA and CRAB in tertiary hospitals was significantly higher than that in secondary hospitals (5.2% vs. 2.5%, 23.8% vs. 12.8% and 53.5% vs. 33.9%, respectively) (all P<0.05). However, the prevalence of ESBL-EC in secondary hospitals was higher than in tertiary ones (63.9% vs. 55.0%, P=0.011). The prevalence of MRSA, CRKP, CRAB, CRPA, ESBL-EC, ESBL-KP in RICU were higher than that in non-ICU respiratory departments (76.5% vs. 35.7%, 20.1% vs. 4.1%, 90.6% vs. 45.5%, 64.2% vs. 19.3%, 47.2% vs. 28.3% and 43.0% vs. 11.2%, respectively) (all P<0.01). Among seven regions in China, central area had the highest detection rates of MRSA (70.3%, 237/337), CRPA (30.9%, 376/1,218), CRAB (71.8%, 487/678) and ESBL-KP (38.8%, 241/621). The prevalence of ESBL-EC and ESBL-KP in pediatric group (68.2% and 55.3%, respectively) was higher than that in geriatric group (54.2% and 27.1%, respectively) and adult group (51.1% and 15.1%, respectively) (all P<0.001). Conclusions: In China, the predominant bacterial pathogens in the respiratory ward were Enterobacteriaceae and non-fermentative bacteria. High prevalence of ESBL-EC and ESBL-KP isolated from lower respiratory tract (LRT) was revealed in primary hospitals and pediatric patients.