Adult Hospitalized Mycoplasma Cases in a Tertiary Hospital in Japan.

Background: Mycoplasma infections have increased globally, including in Japan. Severe pneumonia due to Mycoplasma pneumoniae (M. pneumoniae) that is resistant to macrolides has been reported in the post-COVID-19 period, but its pathogenesis and detailed treatment regimens are still unclear.

Case series: Four adult cases of M. pneumoniae pneumonia that required admission to the hospital in the 2024-2025 season are presented. Case 1: a 17-year-old male without a specific medical history who was admitted with pneumonia with a severe dry cough. Mycoplasma. pneumoniae genes were detected by multiplex PCR from his sputum. The patient's condition improved with minocycline and corticosteroids for 5 days. Case 2: a 88-year-old man with acute kidney injury who was admitted with severe respiratory failure. Mycoplasma antigen was detected in his pharyngeal swab. He received lascufloxacin drip infusion with corticosteroids for 10 days, and soon improved. Case 3: a 38-year-old woman with maxillary carcinoma and a history of aplastic anemia who was admitted with a severe cough. Mycoplasma antigen was detected in her pharyngeal swab. She received minocycline and corticosteroid drip infusion for 1 week, and finally improved. Case 4: a 74-year-old man with multiple systemic atrophies who was admitted with a severe cough and dyspnea. Mycoplasma antigen was detected from his pharyngeal swab and methicillin-susceptible Staphylococcus aureus (MSSA) was isolated from his sputum. The patient was diagnosed with co-infection with mycoplasma and MSSA. He was treated with sulbactam/ampicillin drip infusion and oral administration of minocycline for 2 weeks, and improved.

Conclusion: All hospitalized adult patients with mycoplasma pneumonia were treated with antibiotics, such as minocycline and fluoroquinolone, along with corticosteroid co-administration, and all of them ultimately improved, although the chest X-ray findings varied. Antibiotics other than macrolides and corticosteroids may be an effective regimen for the treatment of severe mycoplasma pneumonia with potential macrolide resistance.