24C / 135 – Pneumococcal vs mycoplasma pneumonia in children: clinical features and laboratory findings

Community acquired pneumonia (CAP) is a common clinical syndrome in a pediatric facility. Strept. pneumoniae remains the most common bacterial pathogen, atypical pneumonias are frequently caused by mycoplasma or chlamydophila species, occasionally viral infections were causes of CAP. Until now, no laboratory test satisfactorily distinguished between the pathogens. Increasing evidence shows that mycoplasma PCR may be promising for the early diagnosis of mycoplasma infections. However, PCR is not routinely available in most clinical laboratories. The aim of this study is to compare the clinical and laboratory features of consolidating lobar pneumonia caused by S pneumoniae and Mycoplasma pneumoniae, seeking factors predicting the bacterial cause of infections and thus able to guide early appropriate use of antibiotics.

We performed a restropective observational analysis on children between 3 – 18 years of age with pulmonary consolidation and admission to the hospital between Jan, 2004 to Dec 2008. Pneumococal pneumonia(PP) was confirmed by the isolation of S pneumoniae in blood culture or pleural fluid. Cases of mycoplasma pneumonia(MP) were recruited from patients who had underwent chest echography studies, confirmed by a 4x titer increase of mycoplasmal antibody (IgM) using the EIA method between acute and convalescent stage; or single positive IgM titer plus cold hemagglutinin titer > 1:64; or PCR positive for mycoplasma antigen. Patients were excluded if the chest radiographs showed only segmental consolidation, or interstitial/peribronchial infiltrates. Co-existing pneumonoccal and mycoplasma infections were also excluded. Demographic data were collected, laboratory findings including leukocytosis (WBC > 20000/mm³, level of C-reactive protein (CRP), presence of coagulopathy were collected. Clinical features regarding the duration of fever after admission, total length of stay during hospitalization were also reviewed and analyzed.

A total of 43 children with CAP were recruited in the study. Twenty-seven patients had bacteria-proven PP, while 16 patients had MP. The mean age of patients with PP were younger than patients with MP (3.4 1.6 yr vs 7.7 3.5 yr). White blood cell counts were significantly elevated in children with PP as compared to MP (18725 12691/mm³ vs. 8750 4593/mm³). CRP was also significant higher in the PP group of patients comparing to MP patients (259.2 103.6 mg/dl vs 135 108.3 mg/dl respectively). Risk factors for PP were WBC > 20000/mm³ 【AOR 13.9 ; CI (1.6 – 120)】, presence of left shift of leukocytes count【AOR 8.6; CI (2.0 – 35.5)】and CRP > 250 mg/dl【AOR 5.4; CI (1.2-23.5)】.