Conclusions:
Although there are some limitations, this is the first study to evaluate the usefulness of combining VBN, ultrathin bronchoscope, ROSE and mNGS to diagnosis infective PPLs. To our knowledge, no other study to date has explored the difference in diagnostic efficacy, the relative abundance of the pathogenic microorganisms and the contamination of common oropharyngeal microbiota amongst the mNGS of BALB, mNGS of BALF and mNGS of BB. We concluded that mNGS from TBLB, BALF or BB is more sensitive than conventional cultures for bacterial infections, fungal infections and general infections, the difference in sensitivity of mNGS between TBLB, BALF, and BB was not statistically significant. mNGS of TBLB had the highest specificity, followed by mNGS of BB, while mNGS of BALF had the lowest specificity, although we did not prove whether the difference between the three is statistically significant. we found that TBLB and BB samples were similar in flora composition except for the richness of common oropharyngeal microbiota, while the relative abundance and richness of common oropharyngeal microbiota in BALF were higher than TBLB. We also found mNGS exhibited its remarkable advantages in detecting pathogens of mixed pulmonary infections in immune-impaired patients. The advantages of mNGS in the field of fungus testing are more prominent than that in the field of bacteria testing. However, mNGS is not omnipotent, for some kinds of microbes, such as cryptococcal pneumonia, mNGS does not have an advantage.
Acknowledgments : we thank to all patients for cooperating with our follow-up and acknowledge all the medical staff involved in the treatment and care of patients for their hard work.
Funding: This research was supported by grants from National Natural Science Foundation of China (81970083, 81270144, 81570084 and 30800507 to J.F), and the National Key Technology R&D Program, China (2015BAI12B00 to J.F).
Conflict of Interest: The authors declare that they have no competing interests in this work and neither the entire paper nor any part of its content has been published. None of the authors has a financial relationship with a commercial entity that has an interest in the subject of this manuscript.
Ethical approval and informed consent: This study was carried out in accord with the principles of the Declaration of Helsinki and approved by the Ethics Review Committee of Tianjin Medical University General Hospital. Patients’ approval and informed consent were waived because the study involved a retrospective review of patients’ record.