Carbapenem-resistant Gram-negative bacilli [Carbapenem-resistant Acinetobacter baumannii (CRAB), Carbapenem-resistant Klebsiella pneumoniae (CRKP), and Carbapenem-resistant Pseudomonas aeruginosa (CRPsA) ] and methicillin-resistant Staphylococcus aureus (MRSA) is prevalent around the world, and the isolation rate and resistance rate has increasing in China. The limited treatment and high mortality rate of these pathogens infections has resulted in difficulty in clinical anti-infection treatment, so it is urgent to illustrate the transmission mechanism, resistance mechanism and horizontal transfer mechanism of resistance genes in intensive care unit (ICU). Furthermore, this study was aimed to investigate the epidemiology and risk factors, outcomes and the rationality of the current therapy for these pathogens infections in China.

Based on the previous study, investigators plan to screen for CRKP, CRAB, CRPsA and MRSA isolates from ICU settings, medical workers and patients, and establish the CRKP, CRAB, CRPsA and MRSA genome and transcriptome database through next-generation sequencing. Under the guide of British bioinformatics and hospital-acquired infection control experts, investigators will build the transmission mechanism model of CRKP, CRAB, CRPsA and MRSA combined with the clinical data to reveal the route and rule of transmission. And the study will also demonstrate that the resistance mechanism and horizontal transfer mechanism of resistance genes of carbapenems and other main antimicrobial agents. Investigators will also set up alerting platform and new antibiotic susceptible system based on the genome and transcriptome. These results will provide scientific evidence to rational application of antimicrobial agents, reduction the prevalence of CRKP, CRAB, CRPsA and MRSA, improvement the prognosis of infections and development of new antimicrobial agents. Finally, to find the prevalence, risk factors, outcome and the rationality of the current therapy for these pathogens infections in China.

Inclusion Criteria:

• Patients infected by CRAB isolated from throat swabs, rectal swabs, gastric tubes, tracheal intubations, tracheostomy tubes, and nasointestinal tubes
• Patients infected by CRKP isolated from throat swabs, rectal swabs, gastric tubes, tracheal intubations, tracheostomy tubes, and nasointestinal tubes
• Patients infected by CRPsA isolated from throat swabs, rectal swabs, gastric tubes, tracheal intubations, tracheostomy tubes, and nasointestinal tubes
• Patients infected by MRSA collected from throat swabs, rectal swabs, gastric tubes, tracheal intubations, tracheostomy tubes, and nasointestinal tubes

Exclusion Criteria:

• Mixed infections of other pathogens
• Virus infections
• Other infections caused by other pathogens, such as fungus

Patients whose primary diagnosis is infections caused by CRAB, CRKP, CRPsA, or MRSA