Molecular characterization of SARS-CoV-2 Omicron clade and clinical presentation in children

Since its emergence, SARS-CoV-2 Omicron clade has shown a marked degree of variability and different clinical presentation compared with previous clades. Here we demonstrate that at least four Omicron lineages circulated in children since December 2021, and studied until November 2022: BA.1 (33.6%), BA.2 (40.6%), BA.5 (23.7%) and BQ.1 (2.1%). At least 70% of infections concerned children under 1 year, most of them being infected with BA.2 lineages (n = 201, 75.6%). Looking at SARS-CoV-2 genetic variability, 69 SNPs were found to be significantly associated in pairs, (phi <  - 0.3 or > 0.3 and p-value < 0.001). 16 SNPs were involved in 4 distinct clusters (bootstrap > 0.75). One of these clusters (A23040G, A27259C, T23617G, T23620G) was also positively associated with moderate/severe COVID-19 presentation (AOR [95% CI] 2.49 [1.26-4.89] p-value: 0.008) together with comorbidities (AOR [95% CI] 2.67 [1.36-5.24] p-value: 0.004). Overall, these results highlight the extensive SARS-CoV-2 Omicron circulation in children, mostly aged < 1 year, and provide insights on viral diversification even considering low-abundant SNPs, finally suggesting the potential contribution of viral diversification in affecting disease severity.

Identification of the blaOXA-23 Gene in the First Mucoid XDR Acinetobacter baumannii Isolated from a Patient with Cystic Fibrosis

Acinetobacter baumannii is one of the pathogens most involved in health care-associated infections in recent decades. Known for its ability to accumulate several antimicrobial resistance mechanisms, it possesses the oxacillinase blaoxa-23, a carbapenemase now endemic in Italy. Acinetobacter species are not frequently observed in patients with cystic fibrosis, and multidrug-resistant A. baumannii is a rare event in these patients. Non-mucoid A. baumannii carrying the blaoxa-23 gene has been sporadically detected. Here, we describe the methods used to detect blaoxa-23 in the first established case of pulmonary infection via a mucoid strain of A. baumannii producing carbapenemase in a 24-year-old cystic fibrosis patient admitted to Bambino Gesù Children's Hospital in Rome, Italy. This strain, which exhibited an extensively drug-resistant antibiotype, also showed a great ability to further increase its resistance in a short time.

A case of SARS-CoV-2 Omicron reinfection resulting in a significant immunity boost in a paediatric patient affected by B-cell acute lymphoblastic leukemia

BACKGROUND

Since its emergence in November 2021, SARS-CoV-2 Omicron clade has quickly become dominant, due to its increased transmissibility and immune evasion. Different sublineages are currently circulating, which differ in mutations and deletions in regions of the SARS-CoV-2 genome implicated in the immune response. In May 2022, BA.1 and BA.2 were the most prevalent sublineages in Europe, both characterized by ability of evading natural acquired and vaccine-induced immunity and of escaping monoclonal antibodies neutralization.

CASE PRESENTATION

A 5-years old male affected by B-cell acute lymphoblastic leukemia in reinduction was tested positive for SARS-CoV-2 by RT-PCR at the Bambino Gesù Children Hospital in Rome in December 2021. He experienced a mild COVID-19 manifestation, and a peak of nasopharyngeal viral load corresponding to 15.5 Ct. Whole genome sequencing identified the clade 21 K (Omicron), sublineage BA.1.1. The patient was monitored over time and tested negative for SARS-CoV-2 after 30 days. Anti-S antibodies were detected positive with modest titre (3.86 BAU/mL), while anti-N antibodies were negative. 74 days after the onset of the first infection and 23 days after the last negative test, the patient was readmitted to hospital with fever, and tested positive for SARS-CoV-2 by RT-PCR (peak of viral load corresponding to 23.3 Ct). Again, he experienced a mild COVID-19. Whole genome sequencing revealed an infection with the Omicron lineage BA.2 (21L clade). Sotrovimab administration was started at the fifth day of positivity, and RT-PCR negativity occurred 10 days later. Surveillance SARS-CoV-2 RT-PCR were persistently negative, and in May 2022, anti-N antibodies were found positive and anti-S antibodies reached titres > 5000 BAU/mL.

CONCLUSIONS

By this clinical case, we showed that SARS-CoV-2 reinfection within the Omicron clade can occur and can be correlated to inadequate immune responses to primary infection. We also showed that the infection's length was shorter in the second respect to first episode, suggesting that pre-existing T cell-mediated immunity, though not preventing re-infection, might have limited the SARS-CoV-2 replication capacity. Lastly, Sotrovimab treatment retained activity against BA.2, probably accelerating the viral clearance in the second infectious episode, after which seroconversion and increase of anti-S antibodies titres were observed.

Plaque calcification is driven by different mechanisms of mineralization associated with specific cardiovascular risk factors

BACKGROUND AND AIMS

The aim of this study was to investigate possible associations among markers of mineralization, plaque instability and the main risk factors of atherosclerosis.

METHODS AND RESULTS

A Tissue MicroArray containing 52 samples of calcified carotid plaques from 52 symptomatic and asymptomatic patients were built. TMA serial sections were used to study the expression of inflammatory and mineralization markers (BMP-2, BMP-4, VDR, RANKL, Osteopontin, Sclerostin, β-catenin and calmodulin) by immunohistochemistry. Our data clearly demonstrated the expression of mineralization markers in atheromatic plaques. Indeed, with the exception of RANKL, all investigated markers were expressed in at least 60% of cases. Specifically, multivariate analysis displayed significant associations between both the expression of BMP-2 and the presence of unstable plaques as well as between the expression of β-catenin and the presence of stable plaques. We also found a significant inverse association between both a) the presence of hypertension and VDR and b) smoking habits and calmodulin expression. Finally, we noted a higher density of RANKL positive cells in plaques from diabetic patients as compared to non-diabetic ones and a significant positive association between hypertriglyceridemia and BMP-4 expression.

CONCLUSION

Our results support the hypothesis that the process of atherosclerotic plaque calcification presents a number of similarities with the physiological processes that occur in bone, involving both osteoblasts- and osteoclasts-like arterial cells. Finally, the present study suggests that risk factors, such as hypertension, cigarette smoke and diabetes, can cause the destabilization of the atheromatic plaque acting on calcification process as well as inflammation.