Professional paper

Influence of PCR inhibitors on molecular diagnosis of pneumococcal pneumonia

Ivana Mareković ; Clinics of pulmonary diseases Jordanovac, Zagreb, Croatia
Vanda Plečko ; Clinical department of clinical and molecular microbiology, Clinical centre Zagreb, Zagreb, Croatia
Zagorka Boras ; Clinics of pulmonary diseases Jordanovac, Zagreb, Croatia
Ladislav Pavlović ; Clinics of pulmonary diseases Jordanovac, Zagreb, Croatia
Ana Budimir ; Clinical department of clinical and molecular microbiology, Clinical centre Zagreb, Zagreb, Croatia
Zrinka Bošnjak ; Clinical department of clinical and molecular microbiology, Clinical centre Zagreb, Zagreb, Croatia
Blanka Kamauf-Balabanić ; Clinics of pulmonary diseases Jordanovac, Zagreb, Croatia
Sonja Marinković ; Clinics of pulmonary diseases Jordanovac, Zagreb, Croatia
Lidija Žele-Starčević ; Clinical department of clinical and molecular microbiology, Clinical centre Zagreb, Zagreb, Croatia
Smilja Kalenić ; Clinical department of clinical and molecular microbiology, Clinical centre Zagreb, Zagreb, Croatia

Abstract

Aim: To determine if inhibitors in blood and respiratory specimens influence the polymerase chain reaction (PCR) results for Streptococcus pneumoniae in patients with community-acquired pneumonia (CAP).
Patients and methods: The study included 80 patients with CAP. In addition to conventional microbiological methods, PCR for fragment of pneumolysin gene in serum (N=77) and BAL (N=19) specimens was also performed. The presence of PCR inhibitors in specimens was determined with spiking and inhibitors were removed by diluting the specimens.
Results: With all methods, S. pneumoniae was detected in 25 (31,3 %) of patients with CAP. PCR results in 77 serum specimens were negative. PCR inhibitors were detected in one serum specimen. BAL specimens were PCR-positive in three patients and there were no inhibitors detected.
Discussion: When planning and performing PCR on clinical specimens, PCR inhibitors should be considered as a possible cause of false-negative results. Several procedures are used to remove PCR inhibitors from clinical specimens or to diminish their influence (extraction method, optimizing DNA amplification, diluting of specimens). Presence of inhibitors can be determined by adding of an internal control to each specimen or with spiking.
Conclusions: In this study the presence of inhibitors was determined in only one serum specimen. It can be concluded that PCR inhibitors in serum and BAL specimens do not influence the PCR results for S. pneumoniae in patients with CAP.

Keywords

blood; bronchoalveolar lavage (BAL); community-acquired pneumonia; inhibition; PCR

Hrčak ID:

31401

URI

https://hrcak.srce.hr/31401

Publication date:

1.12.2008.

Article data in other languages: croatian

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