Longitudinal dynamics of SARS-CoV-2 anti-receptor binding domain IgG antibodies in a wide population of health care workers after BNT162b2 vaccination.

OBJECTIVES: With the availability of vaccines, commercial assays detecting anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies evolved toward quantitative assays directed to the spike glycoprotein or its receptor-binding domain (RBD). The objective was to perform a large-scale, longitudinal study involving health care workers (HCWs), with the aim of establishing the kinetics of immune response throughout the 9-month period after receipt of the second dose of the BNT162b2 vaccine. METHODS: Quantitative determination of immunoglobulin (Ig) G antibodies against the RBD of the S1 subunit of the spike protein of SARS-CoV-2 on the Alinity systems. RESULTS: The highest levels of anti-RBD IgG were measured after 1 month from full vaccination (median: 1432 binding antibody units/ml [BAU/ml]); subsequently, a steep decrease (7.4-fold decrease) in IgG levels was observed at 6 months (median: 194.3 BAU/ml), with a further 2.5-fold decrease at 9 months (median: 79.3 BAU/ml). Furthermore, the same data, when analyzed for sex, showed significant differences between male and female participants at both 1 and 9 months from vaccination, but not at 6 months. CONCLUSION: Our results confirm the tendency of anti-RBD antibodies to decrease over time, also when extending the analysis up to 9 months, and highlight a better ability of the female sex to produce antibodies 1 month and 9 months after vaccination. Overall, these data, obtained in a wide population of HCWs, support the importance of having increased the vaccine doses.

Comparison of Allplex™ SARS-CoV-2 Assay, Easy SARS-CoV-2 WE and Lumipulse quantitative SARS-CoV-2 antigen test performance using automated systems for the diagnosis of COVID-19.

Diagnostic methods based on SARS-CoV-2 antigen detection are a promising alternative to SARS-CoV-2 RNA amplification. We evaluated the automated chemiluminescence-based Lumipulse® G SARS-CoV-2 Ag assay as compared to real time assays (combined results from RT-PCR Allplex™ SARS-CoV-2 assay and Easy SARS-CoV-2 WE kit) on 513 nasopharyngeal swabs (NPS). Among these, 53.6% resulted positive to RT-PCR, considered as the reference test. Compared to the reference test, overall sensitivity and specificity of Lumipulse® G SARS-CoV-2 Ag assay were 84.0%, and 89.1%, respectively, and overall agreement between the antigen and molecular assays was substantial (κ = 0.727). When stratifying samples into groups based on ranges of RT-PCR cycle threshold (Ct), the antigen test sensitivity was >95% for samples with Ct <30. Linear regression analysis showed strong and highly significant correlation between the Lumipulse Ag concentrations and the RT-PCR Ct values (RdRp gene), irrespective of whether the Ct values from molecular test were combined in a unique regression analysis or analysed separately. Overall, chemiluminescence-based antigen assay may be reliably applied to NPS samples to identify individuals with high viral loads, more likely to transmit the virus.

Reasons for SARS-CoV-2 infection in children and their role in the transmission of infection according to age: a case-control study.

BACKGROUND: The locations where children get exposed to SARS-CoV-2 infection and their contribution in spreading the infection are still not fully understood. Aim of the article is to verify the most frequent reasons for SARS-CoV-2 infection in children and their role in the secondary transmission of the infection. METHODS: A case-control study was performed in all SARS-CoV-2 positive children (n = 81) and an equal number of age- and sex- matched controls who were referred to the S. Camillo-Forlanini Pediatric Walk-in Center of Rome. The results of all SARS-CoV-2 nasopharyngeal swabs performed in children aged < 18 years from October 16 to December 19, 2020 were analyzed. RESULTS: School contacts were more frequent in controls than in cases (OR 0.49; 95% CI: 0.3-0.9), while household contacts were higher in cases (OR 5.09; 95% CI: 2.2-12.0). In both cases and controls, school contacts were significantly less frequent, while on the contrary household contacts seemed to be more frequent in nursery school children compared to primary school or middle/high school children. A multivariate logistic regression showed that the probability of being positive to SARS-CoV-2 was significantly lower in children who had school contacts or who had flu symptoms compared to children who had household contacts. Results showed a 30.6% secondary attack rate for household contacts. CONCLUSION: In our study population, the two most frequent reasons for SARS-CoV-2 infection were school and home contacts. The risk of being positive was 5 times lower in children who had school contacts than in children who had household contacts.

Serological response to COVID-19 vaccination in patients with cancer older than 80 years.

Central studies carried out on vaccines against the severe acute respiratory syndrome coronavirus 2 (SARS-COV2) excluded patients receiving immunosuppressive therapy and those diagnosed with an immunosuppressive condition. Moreover, there are no data on vaccine efficacy regarding older patients with cancer. OBJECTIVES: The primary objective was to evaluate the seroprevalence of the SARS-CoV2 IgG in older patients (aged ≥80 years) diagnosed with solid or hematological malignancies, one month after administering the second dose of the BNT162b2 vaccine. MATERIALS AND METHODS: We screened 74 older patients with cancer, 45 of them accepted to receive the vaccination and collected serum samples from 36 patients; a group of medical doctors and nurses from our hospital was used as a control in a 1:2 ratio. RESULTS: The median age was 82 years (range 80-89). Median serum IgG were 2396,10 AU/ml (range 0-32,763,00) in patients with cancer and 8737,49 AU/ml (398.90-976,280,00) in the control group, p < 0.0001. Additional subgroup analyses were performed comparing males and females, patients treated with chemotherapy versus other therapies (immunotherapy, targeted therapy), solid tumors versus hematological malignancies, early (I-II) versus advanced (III-IV) stage of disease, continuative corticosteroid use or not. None of them reached statistical significance. CONCLUSION: Our study shows for the first time that patients with cancer aged ≥80 years can have a serological response to the BNT162b2 COVID-19 vaccine one month after vaccination and consequently support the vaccination campaign currently underway in this frail population.

Lack of relationship between genotype and virulence in Candida species / Ausencia de relación entre el genotipo y la virulencia en especies de Candida

BACKGROUND: The virulence of isolates among different Candida species causing candidemia may play a role in the prognosis of the patients. Furthermore, the potential relationship between genotype and virulence is still unclear and need to be further studied. AIMS: We aim to assess the relationship between genotype and virulence in Candida species using a Galleria mellonella larvae infection model. METHODS: One hundred and ninety-four isolates from 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) were compared against the same number of each species singleton genotypes in terms of survival of G. mellonella larvae. RESULTS: The median of survival and the IQR ranges of clusters and singleton were as follows: C. albicans (2 days, IQR 1.5-2 vs. 2 days, IQR 1-2.25), C. parapsilosis (2 days, IQR 1.5-2.6 vs. 2 days, IQR 2-3.3), and C. tropicalis (1 day, IQR 1-3.5 vs. 2 days, IQR 2-3.5; p < 0.05). High intra-cluster variability in terms of median of survival was found regardless the species. CONCLUSIONS: No relationship between genotype and virulence in Candida was observed with the G. mellonella model

ANTECEDENTES: La virulencia de cepas de diferentes especies de Candida causantes de candidemia puede jugar un papel en el pronóstico de los pacientes, y su estudio en el modelo de infección en Galleria mellonella puede ser útil para entender su contribución general a la infección. Además, la potencial relación entre genotipo y virulencia requiere de más estudios. OBJETIVOS: Se evaluó la relación entre genotipo y virulencia en especies de Candida mediante el modelo de infección de larvas de G. mellonella. MÉTODOS: Se estudió la supervivencia de las larvas infectadas con 194 aislados incluidos en 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) y con el mismo número de aislados con genotipos únicos por especie. RESULTADOS: La mediana de supervivencia y los rangos intercuartílicos (IQR) de clusters y genotipos únicos se muestra a continuación: C. albicans (2 días, IQR: 1,5-2 vs. 2 días, IQR: 1-2,25), C. parapsilosis (2 días, IQR: 1,5-2,6 vs. 2 días, IQR: 2-3,3), y C. tropicalis (un día, IQR: 1-3,5 vs. 2 días, IQR: 2-3,5; p < 0,05). Encontramos una importante variabilidad en la mediana de supervivencia entre cepas del mismo cluster, independientemente de la especie analizada. CONCLUSIONES: No se encontró relación entre el genotipo y la virulencia entre los aislados de Candida evaluados mediante el modelo de infección de G. mellonella

Lack of relationship between genotype and virulence in Candida species.

BACKGROUND: The virulence of isolates among different Candida species causing candidemia may play a role in the prognosis of the patients. Furthermore, the potential relationship between genotype and virulence is still unclear and need to be further studied. AIMS: We aim to assess the relationship between genotype and virulence in Candida species using a Galleria mellonella larvae infection model. METHODS: One hundred and ninety-four isolates from 68 clusters (Candida albicans, 114/41; Candida parapsilosis, 74/24; Candida tropicalis, 6/3) were compared against the same number of each species singleton genotypes in terms of survival of G. mellonella larvae. RESULTS: The median of survival and the IQR ranges of clusters and singleton were as follows: C. albicans (2 days, IQR 1.5-2 vs. 2 days, IQR 1-2.25), C. parapsilosis (2 days, IQR 1.5-2.6 vs. 2 days, IQR 2-3.3), and C. tropicalis (1 day, IQR 1-3.5 vs. 2 days, IQR 2-3.5; p<0.05). High intra-cluster variability in terms of median of survival was found regardless the species. CONCLUSIONS: No relationship between genotype and virulence in Candida was observed with the G. mellonella model.

Genotyping Reveals High Clonal Diversity and Widespread Genotypes of Candida Causing Candidemia at Distant Geographical Areas.

The objectives of this study were to gain further insight on Candida genotype distribution and percentage of clustered isolates between hospitals and to identify potential clusters involving different hospitals and cities. We aim to genotype Candida spp. isolates causing candidemia in patients admitted to 16 hospitals in Spain, Italy, Denmark, and Brazil. Eight hundred and eighty-four isolates (Candida albicans, n = 534; C. parapsilosis, n = 282; and C. tropicalis, n = 68) were genotyped using species-specific microsatellite markers. CDC3, EF3, HIS3, CAI, CAIII, and CAVI were used for C. albicans, Ctrm1, Ctrm10, Ctrm12, Ctrm21, Ctrm24, and Ctrm28 for C. tropicalis, and CP1, CP4a, CP6, and B for C. parapsilosis. Genotypes were classified as singletons (genotype only found once) or clusters (same genotype infecting two or more patients). Clusters were defined as intra-hospital (involving patients admitted to a single hospital), intra-ward (involving patients admitted to the same hospital ward) or widespread (involving patients admitted to different hospitals). The percentage of clusters and the proportion of patients involved in clusters among species, genotypic diversity and distribution of genetic diversity were assessed. Seven hundred and twenty-three genotypes were detected, 78 (11%) being clusters, most of which (57.7%; n = 45/78) were intra-hospital clusters including intra-ward ones (42.2%; n = 19/45). The proportion of clusters was not statistically different between species, but the percentage of patients in clusters varied among hospitals. A number of genotypes (7.2%; 52/723) were widespread (found at different hospitals), comprising 66.7% (52/78) of clusters, and involved patients at hospitals in the same city (n = 21) or in different cities (n = 31). Only one C. parapsilosis cluster was a widespread genotype found in all four countries. Around 11% of C. albicans and C. parapsilosis isolates causing candidemia are clusters that may result from patient-to-patient transmission, widespread genotypes commonly found in unrelated patients, or insufficient microsatellite typing genetic discrimination.

Candidemia Candida albicans clusters have higher tendency to form biofilms than singleton genotypes†.

The capacity of Candida spp. to form biofilms allows them to attach either to living or inert surfaces, promoting their persistence in hospital environments. In a previous study, we reported strain-to-strain variations in Candida spp. biofilm development, suggesting that some genotypes may be greater biofilm formers than others. In this study, we hypothesize that isolates pertaining to clusters may be found more frequently in the environment due to their ability to form biofilms compared to singleton genotypes. Two hundred and thirty-nine Candida spp. isolates (78 clusters) from candidemia patients admitted to 16 hospitals located in different cities and countries-and the same number of singleton genotypes used as controls-were tested in terms of biofilm formation using the crystal violet and the XTT reduction assays. Candida albicans clusters showed higher biofilm formation in comparison to singleton genotypes (P < .01). The biofilms formed by intra-hospital C. albicans clusters showed higher metabolic activity (P < .05). Furthermore, marked variability was found among species and type of cluster. We observed that the higher the number of isolates, the higher the variability of biofilm production by isolates within the cluster, suggesting that the production of biofilm by isolates of the same genotype is quite diverse and does not depend on the type of cluster studied. In conclusion, candidemia Candida spp. clusters-particularly in the case of C. albicans-show significantly more biomass production and metabolic activity than singleton genotypes.

Simplified Testing Method for Direct Detection of Carbapenemase-Producing Organisms from Positive Blood Cultures Using the NG-Test Carba 5 Assay.

We directly tested 484 organisms from clinical (n = 310) and simulated (n = 174) positive blood cultures using the NG-Test Carba 5 assay for carbapenemase-producing Enterobacterales detection. The assay identified all but 4 of the KPC (170/171), OXA-48-like (22/22), VIM (19/21), and NDM (14/15) producers with no false positives. Among the clinical Klebsiella pneumoniae organisms tested, 122 of 123 KPC, 1 of 1 OXA-48-like, and 1 of 2 VIM producers were detected by the assay. Some VIM and NDM producers yielded scant but still-readable bands with the assay. No organisms produced the IMPs that the assay was designed to detect.

Direct maldi-tof mass spectrometry assay of blood culture broths for rapid identification of Candida species causing bloodstream infections: an observational study in two large microbiology laboratories.

We evaluated the reliability of the Bruker Daltonik's MALDI Biotyper system in species-level identification of yeasts directly from blood culture bottles. Identification results were concordant with those of the conventional culture-based method for 95.9% of Candida albicans (187/195) and 86.5% of non-albicans Candida species (128/148). Results were available in 30 min (median), suggesting that this approach is a reliable, time-saving tool for routine identification of Candida species causing bloodstream infection.

Phylogenetic background and virulence genotype of ciprofloxacin-susceptible and ciprofloxacin-resistant Escherichia coli strains of human and avian origin.

BACKGROUND: Previous studies have suggested that fluoroquinolone-resistant strains of Escherichia coli that infect humans probably emerged as a consequence of using fluoroquinolones in poultry. This study aims to provide further insight into the possible avian origin of fluoroquinolone-resistant extraintestinal pathogenic E. coli (ExPEC) strains that infect humans. METHODS: We compared the phylogenetic backgrounds, virulence gene profiles, and genetic relatedness of 125 ExPEC strains recovered from humans (61 were ciprofloxacin susceptible and 64 were ciprofloxacin resistant) and 113 E. coli strains recovered from poultry (47 were ciprofloxacin susceptible and 66 were ciprofloxacin resistant). RESULTS: Ciprofloxacin-resistant strains of both human and avian origin harbored fewer virulence genes than did ciprofloxacin-susceptible strains, but ciprofloxacin-resistant strains from humans were found to be clearly distinct from ciprofloxacin-resistant avian strains, based on their phylogenetic backgrounds and virulence gene profiles. The phylogenetic background of ciprofloxacin-susceptible and ciprofloxacin-resistant strains of human origin was not different, and no shift from the phylogenetic group B2 toward other groups was detected in association with ciprofloxacin resistance. No genetic relatedness was observed among human and avian strains that belonged to the major virulence profile (traT-iucD-iutA). CONCLUSIONS: Our results did not support the hypothesis of an avian origin for the ciprofloxacin-resistant human ExPEC strains analyzed. Nevertheless, prudent use of fluoroquinolones in both human and veterinary medicine is recommended.

An uncommon presentation for a severe invasive infection due to methicillin-resistant Staphylococcus aureus clone USA300 in Italy: a case report.

BACKGROUND: Methicillin resistant Staphylococcus aureus (MRSA) has been considered for many years a typical nosocomial pathogen. Recently MRSA has emerged as a frequent cause of infections in the community. More commonly, community-acquired (CA)-MRSA is a cause of infections of the skin and soft-tissues, but life-threatening infections such as necrotizing pneumonia and sepsis can occasionally occur. CASE PRESENTATION: This report describes an uncommon presentation of invasive CA-MRSA infection in an adolescent without known risk factors. The presentation was typical for bacterial meningitis, but the clinical findings also revealed necrotizing pneumonia. Following the development of deep venous thrombosis, the presence of an inherited thrombophilic defect (factor V Leiden) was detected. The patient was successfully treated with an antibiotic combination including linezolid and with anticoagulant therapy. CA-MRSA was isolated from both cerebrospinal fluid and blood. The isolates were resistant to oxacillin and other beta-lactam antibiotics and susceptible to the other antibiotics tested including erythromycin. Molecular typing revealed that the strains contained the Panton-Valentine leukocidin genes and type IV SCCmec, and were ST8, spa type t008, and agr type 1. This genetic background is identical to that of the USA300 clone. CONCLUSION: This report highlights that meningitis can be a new serious presentation of CA-MRSA infection. CA-MRSA strains with the genetic background of the USA300 clone are circulating in Italy and are able to cause severe infections.