Clinical Features of Severe Mycoplasma vs Bacterial Pneumonia

Source: Liu J, Bao B, Zhang T, et al. Comparative analysis of the clinical characteristics of severe Mycoplasma pneumoniae pneumonia and severe bacterial pneumonia in children. BMC Pediatr. 2025;25(1):439; doi: 10.1186/s12887-025-05804-4.Investigators from Zhengzhou University and Henan University of Chinese Medicine, both in Zhengzhou, China, conducted a retrospective study to compare the demographic and clinical characteristics of children with severe Mycoplasma pneumoniae (MP) to those with either Streptococcus pneumoniae (SP) or Haemophilus influenzae (HI) pneumonia. Study participants were patients ≤18 years old admitted to a single center in China between January 2020 and October 2024 with severe pneumonia caused by MP, SP, or HI. Specific criteria were used to define severe pneumonia, including fever for >5 days, respiratory distress, oxygen saturation <92%, general signs of toxicity, and/or CT findings. MP cases were confirmed based on a positive PCR assay of a throat swab or bronchoalveolar lavage fluid (BALF) sample, and SP and HI were confirmed as the causative agent using sputum or BALF culture results. The medical records of study children were reviewed and demographic and clinical information abstracted. Data on laboratory tests during the first 24 hours of admission, chest CT findings, and bronchoscopy results also were collected. Characteristics of patients in the 3 groups were compared using t-tests, ANOVA, chi square, and rank sum tests.There were 316 children included in the analysis, 130 with MP severe pneumonia, 81 with SP, and 105 with HI. Children with MP severe pneumonia were significantly older than those in the SP and HI group (median age, 45.5, 18.0, and 14.0 months, respectively; P <0.001); those with SP were older than those with HI pneumonia (P = 0.049). Patients with MP had a median of 7.0 days of fever, compared to 4.0 days and 5.0 days, respectively, for those with SP or HI severe pneumonia (P <0.001). White blood cell counts were significantly lower in those with MP pneumonia than those with SP or HI pneumonia (median, 8.61, 10.07, and 10.46 x 109/L, respectively; P <0.001), while erythrocyte sedimentation rates and IL-6 levels were significantly higher. Chest CTs were obtained on all study children. 'Patchy shadows' were more likely to be unilateral in those with MP, than in patients in the SP and HI groups (35.5%, 9.9%, and 1.0%, respectively; P <0.001). Lung consolidation was present in 73.8% of children with MP severe pneumonia, 39.5% of those with SP, and 28.6% of patients with HI (P <0.001). Bronchoscopy was performed in 79 (61%) of children in the MP group, 31 (38.4%) of those with SP, and 27 (25.7%) of children with HI. Among these children, sputum plugs were more commonly seen in those with MP than in patients in the other 2 groups (P = 0.046).The authors conclude that children with severe pneumonia caused by MP had different characteristics and clinical findings than those with SP or HI as the causative agent.Dr Loyal has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.Mycoplasma activity in US children <5 years old increased in 2024, potentially reflecting a shift in epidemiology resulting from the COVID-19 pandemic.1 Macrolide resistance is increasing, approximately <10% in the US overall and approximately 80% in China.1 In the current study, investigators in China report clinical, imaging, and laboratory features that may help distinguish severe MP from SP or HI pneumonia in hospitalized children.The current study is of particular interest because among most hospitalized children in the US with suspected MP infection, advanced diagnostic evaluations such as BAL, sputum cultures, chest CT, bronchoscopy, and measurement of IL-6, creatine kinase, lactate dehydrogenase, and D-dimer levels are not routinely performed outside of an intensive care unit. The current investigators found higher pro-inflammatory cytokines, specifically IL-6 and D-dimers, in children with MP pneumonia. The role of specific cytokines in MP infection and how this information can be used to distinguish MP from other etiologies requires further investigation.Children with MP in the current study were older than those with SP and HI pneumonia, consistent with prior research.1,2 Longer length of hospital stay in the MP patients may have been related to higher macrolide resistance in this region and resulting treatment failure. The finding that wheezing symptoms were more likely in children <18 months with bacterial pneumonia is difficult to interpret. The Henan province in China where the current study was conducted has considerable air quality concerns and high exposure to pollutants.3 Might regional environmental exposures contribute to airway hypersensitivity and wheezing among children?Children with MP pneumonia may have features, including age, elevation in specific cytokines, and early imaging findings, distinguishing them from those with severe bacterial pneumonia.As respiratory tract carriage rates of SP ranges from 20% to 90% and that of MP 17% to 25% in children, it is difficult to ascribe etiology of severe pneumonia based solely on throat or sputum cultures, especially in young children.2