SARS-CoV-2 is constantly evolving, leading to new variants. We analysed data from 4400 SARS-CoV-2-positive samples in order to pursue epidemiological variant surveillance and to evaluate their impact on public health in Italy in the period of April–December 2021. The main circulating strain (76.2%) was the Delta variant, followed by the Alpha (13.3%), the Omicron (5.3%), and the Gamma variants (2.9%). The B.1.1 lineages, Eta, Beta, Iota, Mu, and Kappa variants, represented around 1% of cases. There were 48.2% of subjects who had not been vaccinated, and they had a lower median age compared to the vaccinated subjects (47 vs. 61 years). An increasing number of infections in the vaccinated subjects were observed over time, with the highest proportion in November (85.2%). The variants correlated with clinical status; the largest proportion of symptomatic patients (59.6%) was observed with the Delta variant, while subjects harbouring the Gamma variant showed the highest proportion of asymptomatic infection (21.6%), albeit also deaths (5.4%). The Omicron variant was only found in the vaccinated subjects, of which 47% had been hospitalised. The diffusivity and pathogenicity associated with the different SARS-CoV-2 variants are likely to have relevant public health implications, both at the national and international levels. Our study provides data on the rapid changes in the epidemiological landscape of the SARS-CoV-2 variants in Italy.

Slightly lower values of viability were obtained in mixed culture, but the ratio between the microorganisms was constant. The survival ofArth, giacomelloi in single culture decreased with increasing growth rate while survNal of Azo. brasilense was directly related to dilution rate.Acetylene reduction activity was generally very low in both single and mixed cultures. Respiration rate was also determined and the mixed culture showed an oxygen uptake rate higher than that of single cultures.

Respiratory activity, molar growth yields, and ATP content in. an Arthrobacter sp. ammonium-limited chemostat culture. Can. J. Microbiol. 29: 11 36-1140.ArthrobacterfIuorescens was grown in chemostat culture under ammonium-limited conditions and respiratory activity; molar growth yields and ATP content were determined over a wide range of dilution rates. Within a range of dilution rates between 0.10 h-' and 0.20 h-', morphological transition occurred, the ratio of cocci to rods appearing inversely related to growth rate. Molar growth yields for both glucose and ammonium decreased with increasing dilution rates because of the higher intracellular polysaccharide content at the lower growth rates. Different metabolic activities were shown in cocci, in rods, and during morphogenesis. A sharp decrease in in situ and potential oxygen quotient (Q(02)) and in ATP content was observed in the range of dilution rates in which morphological changes occurred.CACCIARI, I., D. LIPPI, S. IPPOLITI et W. PIETROSANTI. 1983. Respiratory activity, molar growth yields, and ATP content in an Arthrobacter sp. ammonium-limited chemostat culture. Can. J. Microbiol. 29: 1136-1 140. ArthrobacterfIuorescens a Ctt mis en cultures continues (chemostat) sous des conditions limittes d'ammonium et d'activitC respiratoire en vue de dCterminer dans une g a m e de taux de dilution les rendements molaires de croissance et la teneur en ATP. A I'intCrieur de cette gamme, entre 0,10 h-' et 0,20 h-', des transitions morphologiques sont survenues et le rapport des formes sphkriques aux formes en bkonnet s'est avCrC inversement relit5 au taux de croissance. Les rendements molaires de croissance, tant pour le glucose que pour l'ammonium, ont dtcru face a une augmentation des taux de dilution en raison de la teneur ClevCe des poly saccharides intracellulaires aux taux infkrieurs de croissance. DiffCrentes activitCs mCtaboliques se sont manifestCes chez les formes sphCriques, chez les bltonnets, et au cours de la morphogenkse. Un dtclin rapide a Ct C observt in situ du quotient oxygkne (Q(02)) potentiel et de la teneur en ATP dans les divers taw de ddution o~ des changements morphologiques sont survenus.[Traduit par le journal]

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