Comparison of cell cultural method and rt-pcr methods in determination of enteroviruses that cause active infection

Central nervous system (CNS) infections includes many clinical forms ; meningitis, encephalitis and encephalomyelitis to brain abscesses. Most of the enteroviral infections require immediate diagnosis and treatment because of the potential for rapid progression, the possibility of permanent neurological damage and death. Aseptic meningitis is an inflammatory brain disease and can be caused by many factors. Viruses are the most common causative agent of aseptic meningitis and enteroviruses (EV) are responsible for 80-95%. Approximately 10-20% of viral encephalitis is caused by enterovirus. Cell culture, serological tests and nucleic acid amplification tests (NAT) are used to detect enterovirus infections. Cell culture is the standard method for the diagnosis of enterovirus infection, but NAT is more widely used in the diagnosis. Adnan Menderes University Medical Faculty (ADÜTF) Hospital Department of Medical Microbiology Laboratory uses Real-Time PCR method for detection of central nervous system infections. It is considered that studying the related samples with routine cell culture method as well as Real-Time PCR method in our laboratory may increase the rate of enterovirus capture and contribute to the interpretation of possible false positive and false negative results 20 CSF samples; from the patients suspected of viral CNS infection sent to investigate the viral meningitis panel by the Real-Time PCR test in ADUTF Hospital Medical Microbiology Laboratories between 01.11.2018 and 01.11.2019; were included in the study. In addition, supernatant obtained from enterovirus positive cell cultures, 2 folds serially diluted with sterile SF. 20 dilution samples, each dilution containing different amounts of enterovirus, were prepared. Each dilution specimen was divided into two aliquots and studied by both cell culture method and real-time PCR method at the same time. All samples were cultured using "shell vial" method using Vero, HEp-2 and RD cell lines. In this study, a higher rate of enterovirus positivity was detected in CSF specimens (20 CSF specimen) with NAT compared with cell culture (%30/%5 respectively). This difference between the methods was thought to be due to the loss of viability of the virus during storage. Due to the small sample amount, the test could not be repeated. Cell culture enterovirus positivity rate is higher than NAT (%85/75 respectively) in the dilution samples prepared from the enterovirus positive cell culture. These dilution samples were not stored and were tested quickly. This showed that transfer and storage of factors greatly affect the isolation rate of the cell culture method. It should be emphasized that NATs used in routine diagnosis should be carefully selected in terms of validation criteria and EV types they can detect. Cell culture method; is time consuming and it requires excess sample inoculation; is not practical for routine applications because. In routine laboratory diagnosis especially for NAT-negative CSF samples, supporting the diagnosis performed in cell culture with the shell vial method together with NAT is thought to be important in increasing diagnostic sensitivity. Key words: Enterovirus, Cell culture, Real-Time PCR