Comparison between five PCR techniques for the diagnosis of SARS-CoV-2.

OBJECTIVE: Since the first cases of SARS-CoV-2 appeared, there have been numerous techniques that have been developed for the diagnosis or monitoring of infection, both direct and serological techniques. Choosing a good diagnostic tool is essential for epidemiological control. The objective was to compare five commercialized RT-PCR techniques in real time, in sensitivity, specificity and agreement for the detection of SARS-CoV-2. METHODS: Five commercial RT-PCR kits for the detection of SARS-CoV-2 were compared. Eight known positive samples were taken and subjected to seven different dilutions or concentrations, and another 135 negative samples were used to determine sensitivity, specificity, and agreement values. RESULTS: The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for the Palex, Roche and GeneXpert techniques with respect to Seegene were identical, corresponding to 98.21%, 100%, 100% and 99.26% respectively. For Becton Dickinson the sensitivity was 89.28%, the specificity of 100%, the PPV of 100% and the NPV of 95.74%. The agreement using the Kappa index for Palex, Roche and GeneXpert was 0.9892, while the agreement for Becton Dickinson was with a Kappa index of 0.9215. CONCLUSIONS: All commercial RT-PCR kits had high sensitivities and specificities, as well as PPV, NPV, and concordance.

[Evaluation of a new device for sample collection, transport and detection of Group B Streptococcus in pregnant women]. / Evaluación de un nuevo dispositivo para la recogida de la muestra, transporte y detección del estreptococo del grupo B en mujeres embarazadas.

We have designed a new device that combines sample collection, transportation, culture and detection of Group B Streptococcus (GBS), requiring no additional processing in the clinical laboratory. The objective was to evaluate the performance of this device for GBS detection in pregnant women. The new prototype was compared to direct plating of vaginal-rectal swabs onto Granada solid media plates. Direct plating method detected 124 positive samples out of 600 (20.6%) whereas the new device detected 10 additional positive samples (134/600, 22.3%). This new device (patent-protected) could be considered for routine GBS screening.

[Development of a PCR for the detection and quantification of parasitism by Demodex folliculorum infestation in biopsies of skin neoplasms periocular area]. / Desarrollo de una PCR para la detección y cuantificación de la parasitación por Demodex folliculorum en biopsias de neoplasias cutáneas del área periocula.

OBJECTIVE: To standardize the relative quantification by mass of tissue parasitism by Demodex folliculorum infestation from neoplastic skin biopsies periocular using molecular amplification to study the possible relationship of the appearance of eyelid basal cell carcinoma with the presence and density of the mite in later works. METHODS: A quantitative PCR was developed real-time probes TaqMan. PCR was tested in a pilot 46 actual biopsy samples nodular basal cell carcinoma series. RESULTS: The sensitivity was placed with a detection limit of between 1 and 10 copies / µl. 50% (23/46) of the biopsies were positive for D. folliculorum. The specificity was 100% confirmed by sequencing. CONCLUSIONS: The technique shows good results for sensitivity and specificity that can make it useful as a tool for studies of cause and effect D. folliculorum and basal cell carcinoma.

[Variability in the sensitivity to tigecycline against Acinetobacter baumannii in different culture media]. / Variabilidad en la sensibilidad de tigeciclina frente a Acinetobacter baumannii en diferentes medios de cultivo.

INTRODUCTION: The tigecycline may represent a therapeutic alternative for the control of multiresistant A. baumannii, although there is no consensus regarding the cutoff points for sensitivity or variability of MIC as a function of culture medium used for the antibiogram against this microorganism. Therefore, our objective was to verify this variability, and propose the culture medium that comes closest to the standard method. METHODS: We selected 41 strains of carbapenem-resistant A. baumannii. We analyzed the sensitivity to tigecycline in different culture media: Mueller Hinton agar Oxoid commercial (C-MH), Mueller Hinton fresh agar BD and Co., USA (F-MH) and ISO-sensitest fresh agar Oxoid, using the E-test and disk. The MICs were compared against those obtained using the technique standard of macrodilution. RESULTS: The mean MIC and inhibition diameters obtained in the different culture media corresponded to 9.26 mg/L and 15.1 mm in diameter for MH-C, 1.71 mg/L and 22.7 mm for MH-F; 2.68 mg/L and 20.8 mm for ISO-sensitest. Half the MIC obtained by the standard method of dilution was 0.47 mg/L (SD =0.21), with values between 0.25 and 1 mg/L. CONCLUSION: In the three growth media studied, MICs superior to the standard are observed, which is false to interpret resistance in many cases. However, the medium that comes closer more that of reference is the MH-F.

[HIV seroprevalence in the population treated in a hospital emergency department: analysis by pooled batches of serum]. / Seroprevalencia del VIH en población atendida en un Servicio de Urgencias: análisis por lotes de sueros.

INTRODUCTION: The current number of Human Immunodeficiency Virus (HIV) infected people is not known in Spain as there is no national registry. This study has aimed to estimate the prevalence of HIV infection in the population treated in a hospital emergency department (ER) as an epidemic and risk of exposure indicator during healthcare activity and to assess the differences observed regarding previous estimates. MATERIAL AND METHODS: We conducted a cross-sectional study of all the sera received in the ER anonymously. The final size of the pools was 5 sera. HIV antibody screening was performed using the 4th generation ELFA technique and confirmation was performed by Western Blot. RESULTS: Seven out of the 270 pools made from 1,347 sera obtained were reactive. The individualized analysis confirmed 6 sera to be positive and 1 serum to be false positive. The observed prevalence was 0.52% (95% CI 0.10-0.94). Prevalence fell 0.87% in comparison to the years 1990-1991, although this was not statistically significant (p = 0.08). DISCUSSION: The implementation of HIV antibodies detection through a system of pooled batches in samples collected in the ER make it possible to assess the prevalence of infection with this virus, decreasing costs with regard to individualized analysis of sera in both economic terms as well as samples handling.