Clinical significance of different bacterial load of Mycoplasma pneumoniae in patients with Mycoplasma pneumoniae pneumonia

OBJECTIVE: This retrospective study was conducted to investigate the clinical significance of different Mycoplasma pneumoniae bacterial load in patients with M. pneumoniae pneumonia (MP) in children. METHODS: Patients with MP (n = 511) were identified at the Children's Hospital Affiliated to Soochow University database during an outbreak of MP between January 2012 and February 2013. RESULTS: Comparing patients with high and low bacterial load those with higher loads were significantly older (p < 0.01) and had fever significantly more frequently (p = 0.01). Presence of wheezing at presentation was associated with low bacterial load (p = 0.03). Baseline positive IgM was present in 93 (56.4%) patients with high bacterial load compared to 46 (27.8%) patients with low bacterial load (p < 0.001). Co-infection with viruses was found significantly more frequent among patients with low bacterial load (24.2%) than those with high bacterial load (8.5%) [p < 0.001]. Bacterial co-infection was also more frequently detected among patients with low bacterial load (22.4%) than in those with high bacterial load (12.1%) [p = 0.01]. CONCLUSION: M. pneumoniae at a high bacterial load could be an etiologic agent of respiratory tract disease, whereas the etiologic role of MP at a low bacterial load remains to be determined.