Association between cycle threshold (Ct ) values and clinical and laboratory data in inpatients with COVID-19 and asymptomatic health workers.

In-house assays for the diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by quantitative reverse-transcription polymerase chain reaction (qRT-PCR), are feasible alternatives, particularly in developing countries. Cycle threshold (Ct ) values obtained by qRT-PCR were compared with clinical and laboratory data from saliva of inpatients with COVID-19 and asymptomatic health workers (AHW) were studied. Saliva specimens from 58 inpatients confirmed by qRT-PCR for SARS-CoV-2 using nasopharyngeal specimens, and 105 AHW were studied by qRT-PCR using three sets of primers for the N (N1, N2, and N3) gene of SARS-CoV-2, according to the CDC Diagnostic Panel protocol, showing a positivity of 88% for inpatients and 8% for AHW. Bivariate analysis revealed an association between Ct < 38.0 values for N2 and mechanical ventilation assistance among patients (p = .013). In addition, values of aspartate-transaminase, lactate dehydrogenase, and ferritin showed significant correlations with Ct values of N1 and N3 genes in inpatients. Therefore, our results show that Ct values correlate with some relevant clinical data for inpatients with COVID-19.

Streptococcus pneumoniae: prevalence in nasopharyngeal carriers of more than 50-years-old, in a Mexican rural community.

INTRODUCTION: Streptococcus pneumoniae (Sp) is the main cause of community-acquired pneumonia in the elderly, hence the importance to establish the prevalence of nasopharyngeal colonization by different Sp serotypes in adults. METHODS: from December 2009 to June 2010, nasopharyngeal cultures were taken from adults living in rural communities in Mexico for the isolation and serotyping of Sp by the Quellung reaction. Penicillin and ceftriaxone susceptibility tests were performed by the microdilution method. RESULTS: two hundred and thirty-six adults over 50 years old, were included. The prevalence of colonization by Sp was 21.6%. The most frequent serotypes were 19A (21%), 6A (13%), 6B and 11A (11%). All isolates were susceptible to ceftriaxone, and 52.8% of the isolates showed penicillin minimal inhibitory concentrations ≥0.12mg/L. CONCLUSION: this is the first study analyzing the nasopharyngeal colonization by Sp in adults in Mexico. Serotypes not included in any of the pneumococcal vaccines were frequently identified.