High ratio of C-reactive protein/procalcitonin predicts Mycoplasma pneumoniae infection among adults hospitalized with community acquired pneumonia

Abstract

There is limited data on serum biomarkers in distinguishing Mycoplasma pneumoniae (MP) from Streptococcus pneumoniae (SP) and viral pneumoniae (VP) etiologies of community-acquired pneumonia (CAP). A retrospective study of inpatients diagnosed with CAP at the First Affiliated Hospital of Dali University (Dali, Yunnan, China) between January 2018 and June 2020 was conducted. The demographic, clinical and laboratory data of the patients with CAP were analyzed. Univariate analyses identified predictors for MP infections. The discriminative power of C-reactive protein (CRP), procalcitonin (PCT), CRP/PCT and CRP/PCT >350 μg/ng was assessed by area under the curve (AUC) of the receiver operating characteristic (ROC) curves. A total of 552 CAP patients, including 247 (44.7%) with MP, 152 (27.6%) with SP and 153 (27.7%) with influenza A and B viruses, were enrolled. When comparing MP with SP, cough and CRP/PCT >350 μg/ng (odds ratio [OR]) 2.88, p < .001) were predictors for MP. CRP/PCT >350 μg/ng had 76% sensitivity and 100% specificity (AUC = 0.89, p < .001, 95% confidence interval [CI]:0.81–0.94) to predict MP infections. Furthermore, similar results were again obtained when comparing MP with VP. CRP/PCT >350 μg/ng present better information (OR: 4.70; AUC = 0.92, p < .001, 87% sensitivity and 100% specificity). In addition, comparing MP and non-MP (SP and VP combined), CRP/PCT >350 μg/ng exhibited excellent performance (AUC = 0.90, 95%CI 0.83–0.95, p < .001, 76% sensitivity and 100% specificity). CRP/PCT ratio may be a potential index to distinguish MP-CAP from non-MP-CAP.

Keywords:

• Community acquired pneumonia
• Mycoplasma pneumoniae
• C-reactive protein
• procalcitonin
• C-reactive protein/procalcitonin ratio
• respiratory infections

Acknowledgments

We thank Dr. Tai Zhang for his contribution towards this study on the choice of statistical methods and analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the National Science Foundation of China under Grant No. [81960363]; Yunnan health training project of high level talents under Grant No. [H-2019045]; and Yunnan Fundamental Research Projects under Grant No. [202001BA070001-151 and 202001BA070001-161].