SUMMARY OBJECTIVE: This study aimed to investigate the effect of mutations by comparing wild-type SARS-CoV-2 and Omicron regarding clinical features in patients with COVID-19. It also aimed to assess whether SARS-CoV-2 cycle threshold value could predict COVID-19 severity. METHODS: A total of 960 wild-type and 411 Omicron variant patients with positive results in SARS-CoV-2 real-time reverse transcriptase polymerase chain reaction test from oropharyngeal and/or nasopharyngeal samples during their hospital admissions were included in this retrospective study. The reference symptoms of the patients were obtained from the hospital database. The correlation between chest computed tomography findings and the “cycle threshold” of patients with wild-type SARS-CoV-2 was assessed. RESULTS: Cough, fever, shortness of breath, loss of taste and smell, and diarrhea were found to be statistically significantly higher (p=0.001; 0.001; 0.001; 0.001; and 0.006; respectively) in the wild-type cohort, while in the Omicron cohort, sore throat and headache were found to be statistically significantly higher (p=0.001 and 0.003, respectively). An inverse relationship was found between chest computed tomography findings and viral load. CONCLUSION: This study revealed that the Omicron variant tended to infect predominantly the upper respiratory tract and showed decreased lung infectivity, and the disease progressed with a milder clinical course. Therefore, the study showed that the tropism of the virus was changed and the viral phenotype was affected. It was also found that SARS-CoV-2 viral load did not predict COVID-19 severity in patients with wild-type SARS-CoV-2.

Introduction. The aim of this prospective singlecenter study was to determine the changings in incidence of invasive pneumococcal disease (IPD), serotype distribution and the antimicrobial resistance patterns of S. pneumoniae in children with IPD after the period (1 to 7 years) of vaccination with PCV7 (2008) and PCV13 (2011). Population and methods. The study was conducted on 39 Turkish children with IPD between ages 1 month and 18 years in Ankara, Turkey. Streptococcus pneumoniae was identified using standard laboratory procedures from blood, cerebrospinal fluid (CSF), pleural fluid, and other sterile body fluids and tissues. S. pneumoniae isolates were tested for resistance to penicilin and ceftriaxone using the E-test methodology. Serotypes of the isolates were determined by Quellung reaction. Results. The overall annual incidence rate of IPD decreased significantly from 7.71 (95% CI, 1.99-13.4) to 1.58 (95% CI, 0.6-3.77; RRR= -79.5; p= 0.006) per 100 000 population among <5 years of age without underlying disease. During the overall study period, the PCV7-serotypes and PCV13-serotypes represented 27.8% and 63.8% of isolates, respectively. PCV13-serotypes made up 81.8% of cases of IPD in the pre-PCV13 era and decreased to 56% in the 4 years after PCV13. The penicillin and ceftriaxone (for meningitis) resistance rates were 48.5% and 9.1%, respectively. Conclusions. This is the first study about the changing pattern of the incidence of IPD in Turkish children after the implementation of the PCV7 and PCV13 in Turkish national vaccine schedule and a prominent decrease in incidence of IPD has seen after the implementation of PCV13.

Introducción: Nuestro objetivo fue determinar los cambios en la incidencia de enfermedad neumocócica invasiva (ENI), la distribución de serotipos y patrones de resistencia antibiótica del Streptococcus pneumoniae en niños con ENI tras el período de vacunación (de 1 a 7 años) con vacuna neumocócica de 7 serotipos (VCN7) (2008) y de 13 serotipos (VCN13) (2011). Población y métodos: El estudio se realizó en 39 niños con ENI de 1 mes a 18 años de edad en Angora, Turquía. Se identificó Streptococcus pneumoniae en sangre, líquido cefalorraquídeo, líquido pleural, y otros tejidos y líquidos corporales estériles mediante procedimientos estándar. Se analizó la resistencia de cepas aisladas de S. pneumoniae a penicilina y ceftriaxona con la prueba de epsilometría (E-test). Los serotipos de las cepas se determinaron con la reacción de Quellung. Resultados: La incidencia anual de ENI disminuyó significativamente de 7,71 (intervalo de confianza |-#91;IC|-#93; del 95%: de 1,99 a 13,4) a 1,58 (IC del 95%: de 0,6 a 3,77; reducción del riesgo relativo= -79,5; p= 0,006) cada 100 000 habitantes de < 5 años de edad sin enfermedad preexistente. Durante todo el período del estudio, los serotipos en la VCN7 y en la VCN13 representaron el 27,8% y el 63,8% de las cepas aisladas, respectivamente. Los serotipos en la VCN13 correspondían al 81,8% de los casos de ENI en la era previa a la introducción de esta vacuna, y disminuyeron al 56% en los cuatro años posteriores. Las tasas de resistencia a penicilina y ceftriaxona (en el caso de la meningitis) fueron del 48,5% y el 9,1%, respectivamente. Conclusiones: Este estudio observó una disminución significativa en la incidencia de ENI después de la introducción de la VCN13.