3. Results
Between July 2018 and July 2019, 12 male and 27 female patients with a
median age of 38 years (15 to 77 years) were enrolled in the present
study. 74% (29/39) patients were
immune-impaired. 33 of the 39 patients were eventually diagnosed with
lung infection, and 6 of the lung lesions were considered for
non-infectious lesions. (9 cases) 23% of the cases were multiple
infections. In the end, 43 infections were diagnosed in 33 patients with
pulmonary infection, including 14 bacterial infections, 21 fungal
pneumonia, 7 viral pneumonia and 1 mycoplasmal pneumonia.
All of the patients in this study
received empiric broad spectrum antibiotics prior to sample collection.
Performance of
conventional culture for the identification of pathogens.
Cultures of BALF were positive in 7 of 43 pulmonary infections.
Pathogenic microorganisms that were positive in culture of BALF include
Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae,
Corynebacterium and fungi. Pathogenic microorganisms detected only by
mNGS, but not by culture, include Nocardia, Mycobacterium tuberculosis,
Pneumocystis jirovecii, Haemophilus parainfluenzae,
Streptococcus_pneumoniae,
Pyramidobacter piscolens and
Prevotella. The culture confirmed the bacterial pathogenic
microorganisms in 2 out of 3 cases of P. aeruginosa pneumonia, 2 out of
2 cases of Klebsiella pneumoniae pneumonia, 1 case of E. coli pneumonia,
and 1 case of Corynebacterium pneumonia. In one case, sputum smear
showed positive acid-fast bacilli, mNGS detected Mycobacterium
tuberculosis, and culture of BALF was negative.
The sensitivity and specificity of
microbial culture for diagnosis of pulmonary infection were 16.3% and
60.0%, respectively. The sensitivity of microbial culture for diagnosis
of bacterial infections and fungal infections were 42.9% and 4.8%,
respectively (Table 1). The positivity rates of mNGS and culture tests
for bacterial infections, fungal infections, general infectious groups
are illustrated in Figure 1. As expected, regardless of bacterial
infections, fungal infections, or general infections, mGNS is more
sensitive than conventional cultures.