Differentiation of viral and bacterial community‐acquired pneumonia in pediatrics

Differentiation of viral and bacterial community‐acquired pneumonia in pediatrics

Ali Azimi,Infectious Diseases Research Center, Kashan University of Medical Sciences, Kashan, Iran

Abstract:

Community acquired pneumonia (CAP) is common in childhood. Viruses account for most cases of CAP during the first two years of life. After this period, bacteria such as Streptococcus pneumoniae, Mycoplasma pneumoniae and Chlamydia pneumoniae become more frequent. CAP symptoms are nonspecific in younger infants, but cough and tachypnea are usually present in older children. Chest x-ray is useful for confirming the diagnosis. Most children can be managed empirically with oral antibiotics as outpatients without specific laboratory investigations. Microbe‐specific diagnosis of pediatric community‐acquired pneumonia (CAP) and the distinction between typical‐bacterial, atypical‐bacterial and viral cases are difficult. The aim of the present study was to evaluate the role of four serum non‐specific inflammatory markers and their combinations, supplemented by chest radiological findings, in the screening of bacterial etiology of pediatric CAP.

Matherial andMethods:  Serum procalcitonin (PCT), serum C‐reactive protein (CRP), blood erythrocyte sedimentation rate (ESR) and white blood cell (WBC) counts were determined in 88children with CAP, all confirmed on chest radiograph. Evidence of etiology was achieved in 58 patients (67%) mainly using a serologic test panel including 15 pathogens.

Findings:  For the combination of CRP > 90 mg/L, WBC count > ۱۵ × ۱۰۹ /L, PCT > ۱٫۰ ng/mL and ESR > ۶۰ mm/h, the likelihood ratio for a positive test result  was 2.7 in the distinction between pneumococcal and viral CAP and 3.9between atypical and viral CAP. If there was a higher value in one of these four parameters (CRP > ۲۰۰ mg/L, WBC count > ۲۲ × ۱۰۹/L, PCT > ۱۸ ng/mL or ESR > ۹۰ mm/h) positive test result  was changed to ≥۳٫۴, which means a significant increase from pre‐test to post‐test disease probability. An alveolar radiological infiltration was associated with higher values in non‐specific inflammatory markers when compared with interstitial infiltrates, but there were no significant associations between radiological and etiological findings.

Conclusions:  CRP, WBC count, PCT and ESR or their combinations have a limited role in screening between bacterial and viral pediatric CAP. If all or most of these markers are elevated, bacterial etiology is highly probable, but low values do not rule out bacterial etiology.

Key Words: Childhood; Community-acquired; Diagnosis; Pneumonia