Clinical characteristics of Mycoplasma pneumoniae compared to Streptococcus pneumoniae in hospitalized adults with community-acquired pneumonia- a prospective study.

BACKGROUND: Streptococcus pneumoniae is the primary cause of hospitalized community-acquired pneumonia (CAP). Mycoplasma pneumoniae, though typically causing mild respiratory disease, can lead to pneumonia requiring hospitalization in adults. This study compared patients hospitalized with CAP caused by M. pneumoniae or S. pneumoniae aiming at increasing the understanding of when to sample for and empirically treat M. pneumoniae. METHODS: From 2016 to 2018, 518 adults hospitalized with CAP were prospectively and consecutively enrolled. Medical history, symptoms, radiographic, and laboratory data were recorded. Naso- and oropharyngeal swabs were collected for PCR detection of M. pneumoniae and other respiratory pathogens, while urine samples were analysed with two pneumococcal urinary antigens. RESULTS: A total of 32 patients with M. pneumoniae and 126 patients with S. pneumoniae were identified. Patients with M. pneumoniae were significantly younger than those with pneumococcal CAP with a median age 39 versus 70 years. Mycoplasma pneumoniae accounted for only 6% of CAP cases across all ages, but for 33% of cases in patients < 50 years. Mycoplasma pneumoniae patients had a longer duration of symptoms and were more often prescribed antibiotics prior to hospital admission. Neither symptoms nor chest imaging alone could distinguish between M. pneumoniae and S. pneumoniae. Although inflammatory markers such as CRP and leukocyte counts were significantly lower in M. pneumoniae CAP, the median CRP value was still elevated at 178 mg/L. Viral co-detection occurred in 14% of M. pneumoniae patients, compared to 42% of those with S. pneumoniae. CONCLUSION: Symptoms and radiological findings could not distinguish between M. pneumoniae and S. pneumoniae. However, in hospitalized patients, particularly in younger individuals or those with antibiotic failure, liberal testing and treatment for M. pneumoniae is recommended.