The Role of Optochin Sensitivity, Bile Solubility and psaA Polymerase Chain Reaction Methods in the Diagnosis of Streptococcus pneumoniae in Respiratory Tract Samples

Abstract

Streptococcus pneumoniae; in addition to serious life-threatening infections such as pneumonia, bacteremia and meningitis, is also an important pathogen which causes common infections such as otitis and sinusitis. The rapid and accurate diagnosis of S.pneumoniae is extremely important for the appropriate treatment of infected patients. In our study, we aimed to compare the specificity and sensitivity of the phenotypic tests used in routine diagnosis with the psaA PCR we used as the gold standard method. 90 strains isolated from the clinical specimens were grouped according to their optochin sensitivity and bile solubility: 30 S.pneumoniae strains (optochin sensitive and bile solubility-drip test positive) (Group 1), 50 non-pneumococcus strains (optochin resistant and bile solubility-drip test negative) (Group 2) and 10 S.pneumoniae suspicious strains (optochin resistant but bile solubility-drip test positive) (Group 3) psaA PCR and bile solubility-tube test were applied to all isolates; the strains in Group 1 were positive and the strains in Groups 2 and 3 were negative. The 10 strains in Group 3 were determined as viridans group streptococci in API 20 Strep test. According to these findings, bile solubility-tube test was found to be more specific than the drip test and similar to psaA PCR method.

Keywords

• Optochin sensitivity
• bile solubility
• psaA PCR

Solunum Yolu Örneklerinde Streptococcus pneumoniae’nin Saptanmasında Optokin Duyarlılığı, Safrada Erime ve psaA Polimeraz Zincir Reaksiyonu Yöntemlerinin Yeri

Abstract

Streptococcus pneumoniae; pnömoni, bakteriyemi ve menenjit gibi hayatı tehdit eden ciddi infeksiyonların yanısıra otit, sinüzit gibi sık rastlanan infeksiyonlara da yol açan önemli bir patojendir. S.pneumoniae’nin hızlı ve doğru tanısı, infekte hastaların uygun tedavi görmesinde son derece önemlidir. Çalışmamızda rutin tanıda kullandığımız fenotipik testlerin özgüllük ve duyarlılığının, altın standart yöntem olarak kullandığımız psaA PCR ile karşılaştırılması amaçlanmıştır. Klinik örneklerden izole edilen 90 adet alfa hemolitik streptokok suşu optokin duyarlılığı ve safrada erime- damlatma testlerine göre; S.pneumoniae olduğu bilinen (optokine duyarlı ve safrada erime-damlatma testi pozitif) 30 suş (Grup 1), S.pneumoniae olmayan (optokine dirençli ve safrada erime-damlatma testi negatif) 50 suş (Grup 2) ve S.pneumoniae şüpheli (optokine dirençli ama safrada erime-damlatma testi pozitif) 10 suş (Grup 3) olmak üzere 3 gruba ayrılmıştır. Tüm izolatlara psaA PCR ve safrada erime-tüp testi uygulanmış; Grup 1 deki suşlar pozitif, Grup 2 ve 3’teki suşlar ise negatif olarak bulunmuştur. Grup 3’teki 10 suşa API 20 Strep testi yapılmış ve viridans grup streptokok olarak tanımlanmıştır. Bu bulgulara göre safrada erime-tüp testinin; damlatma testine göre daha özgül, psaA PCR yöntemiyle ise benzer özgüllüğe sahip olduğu görülmüştür.

Keywords

• Optokin duyarlılığı
• safrada erime
• psaA PCR

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