To analyze the clinical characterization of Mycoplasma pneumoniae pneumonia (MPP) in adults.

The clinical data of 74 MPP patients diagnosed by targeted next-generation sequencing (tNGS) pathogenetic testing in the Department of Respiratory and Critical Care Medicine of the Affiliated Guangdong Second Provincial General Hospital were retrospectively analyzed from April 1, 2023, to November 30, 2023, and divided into 22 cases of hypoxia( PaO₂≤80 mmHg) in the observation group and 52 cases of non-hypoxia (PaO₂≥80 mmHg) in the control group, to explore the clinical characteristics of adult MPP.

Among the 74 patients with MPP, 48 cases(64.86%) were females, the prevalent age group was 18 to 44 years old in 55 cases(74.32%), and the main clinical symptoms were cough in 74 cases (100.00%), cough sputum in 67 cases (90.54%), and fever in 60 cases (81.08%). There were 61 cases (82.43%) without underlying disease, 57 cases (77.03%) with detection of macrolide resistance gene, and 68 cases (91.89%) with MP mono-infection. The differences in maximum body temperature >38 ℃[20 cases(90.91)vs. 32 cases(61.54)], PaO₂[ (72.42±11.12) vs. (92.93±11.07)]mmHg and the number of MP homogenization sequences [(37 241.82±20 530.88) vs. (24 352.08±16 835.32)]between the observation group and the control group were statistically significant (P<0.05), and the differences in gender, age, duration of illness >7 days before admission, clinical symptoms, pulmonary rales, pH, PaCO₂, HCO₃^-, history of antibiotic exposure, underlying disease history, days of hospitalization, detection of drug-resistant genes, and MP single infection were not statistically significant (P>0.05), and the differences in leukocytes[(8.06±1.91) vs. (6.63±1.82)] ×10⁹/L, neutrophils[(5.86±1.85) vs. (4.41±1.58)]×10⁹/L, and C-reactive protein [(48.21±47.09) vs. (31.55±19.64)]mg/L between the two groups were statistically significant (P<0.05), while the differences in monocytes and lymphocytes were not statistically significant (P>0.05). There was no statistically significant difference in the distribution site of chest CT lesions, lesion morphology, mediastinal lymph node enlargement, and pleural effusion between the two groups of patients (P>0.05).

Adult MPP patients are more often female than male, and occur in young people without underlying diseases, with nonspecific clinical manifestations, mainly cough, sputum, and fever. MPP patients have a high rate of mutations in macrolide-resistant genes, and a few of them have co-infections, with a tendency to develop hypoxemia or even progress to severe disease when they have a moderately high degree of fever, a high number of MP homogenization sequences on tNGS, and an elevated number of inflammatory markers.