Background: Klebsiella pneumoniae  has been a leading healthcare-acquired infection (HAI) agent worldwide for decades. However, the epidemiological characteristics of K. pneumoniae  in lung cancer patients with respiratory infection are unclear. Here, we characterized the frequency of K. pneumoniae  in lung cancer patients with respiratory infection in a cancer hospital in China and determined the antibiotic resistance profile, virulence phenotype and clonal relationships among these K. pneumoniae  strains.
Methods: The clinical data of lung cancer patients with respiratory infection from September 2017 to October 2018 were retrospectively evaluated. Microbiological methods, antimicrobial susceptibility tests, pulsed-field gel electrophoresis (PFGE), polymerase chain reaction (PCR) assays, Sanger sequencing and Galleria mellonella  larvae infection model were used in this study.
Results: During the study period, a total of 47 lung cancer patients with respiratory infection caused by bacteria were identified, among 27 patients were identified as positive for K. pneumoniae  and the positive rate was 57.45%. Among 37 nonduplicate K. pneumoniae  strains from these 27 patients, 19 isolates (51.4%) were classified as multidrug resistant (MDR) with high-level resistance to, at least one agent in three or more antibiotic categories, including polymyxin B and tigecycline. Sixteen of the 37 strains (43.2%) were hypermucoviscous isolates. Extended spectrum β-lactamases-producing K. pneumoniae  strains consisted of two dominant PFGE types. Furthermore, the assessment of virulence potential using a G. mellonella  larvae infection model showed that K. pneumoniae  isolated from these patients exhibited a high virulence level.
Conclusion: Our data showed that K. pneumoniae  is the most critical cause of lung infection in patients with lung cancer in this hospital. The various drug resistance and virulence backgrounds of K. pneumoniae  may make this clinical center a breeding ground for superbugs. It is paramount to enhance surveillance of K. pneumoniae  strains and take control measures.
Keywords: K. pneumoniae , lung cancer, multidrug-resistant, virulence