Assess the correlation between Xpert Carba-R detection of carbapenemase gene types in bronchoalveolar lavage samples and rectal swab samples from non-colonized CRKP patients with lower respiratory tract infections, and evaluate the relationship between first-time lower respiratory tract infections and intestinal colonization of CRKP.

Inclusion Criteria:

• Aged 18 years and above
• CRKP is cultured from lower respiratory tract specimens in 15 days
• Lower respiratory tract infection based on at least two of the followings: abnormal temperature (body temperature greater than 38.5°C or less than 36.5°C), leucocyte count abnormality (leucocyte count greater than 10*10^9/L or less than 4*10^9/L), and the presence of purulent tracheal secretions.

Exclusion Criteria:

• There are other bacteria that can produce carbapenemases exist in lower respiratory tract specimens
• Infected with CRE before

The study population description specifies individuals diagnosed with LRTI (Lower Respiratory Tract Infection) who were enrolled based on culture-confirmed CRKP（Carbapenem-resistant Klebsiella pneumoniae）.