Discrimination of Streptococcus pneumoniae from other upper respiratory tract streptococci by arbitrarily primed PCR

Objectives: In the clinical laboratory, identification of Streptococcus pneumoniae can be confused with other streptococci. Conventional biochemical tests such as optochin sensitivity and bile solubility can give inconsistent results. This report presents a method to distinguish true S. pneumoniae from other upper respiratory tract streptococci when conventional tests fail.

Design and Methods: We used arbitrarily primed polymerase chain reaction with the single primer M13 universal as a method to distinguish S. pneumoniae from other upper respiratory tract streptococci.

Results: The fingerprint pattern of S. pneumoniae was established by amplifying DNA of S. pneumoniae type strains 1–48 and of other common upper respiratory tract streptococci at three different DNA concentrations with the single primer M13 universal. From these type strains, a common arbitrarily primed-polymerase chain reaction pattern was identified characterized by two predominant bands of equal intensity at 800 base pairs and at 1100 base pairs. Fingerprint patterns of viridans streptococci were easily distinguishable from those of S. pneumoniae. Many of the clinical isolates used in this study were equivocal by conventional tests but were distinguishable by their fingerprint patterns.

Conclusions: Our results indicated that the fingerprint pattern of S. pneumoniae is species specific and distinguishes true S. pneumoniae of clinical isolates from other streptococci when conventional biochemical tests are unclear.