As opposed to adults, children cannot produce sputum (lower respiratory sample) appropriate for culture which is the traditional method of identifying the causative bacteria. Identification of bacteria in nasopharyngeal secretions (upper respiratory sample) does not equate to that organism causing the infection as the upper airway of a child is often colonized by bacteria. Detecting the organism in blood identifies it as the causative organism. However, blood culture has a very low yield in children with pneumonia and polymerase chain reaction (PCR) is much more sensitive at detecting bacteria in blood and hence it will markedly improve the ability to determine infecting organism.