SARS-CoV-2 RNA presence and infectivity in wastewaters and receptors was assessed. • Viral RNA was detectable in the inflow but not in the outflow wastewaters. • Viral RNA was present in receptors due to sewage overflows or inefficient treatment. • SARS-CoV-2 infectivity was null both in wastewaters and receptors. • A precautionary approach in the assessment of contagious risk is advocated.

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Wastewater-based epidemiology has been proposed to monitor the diffusion and trend of SARS-CoV-2 pandemic. In the present study, raw and treated samples from three wastewater treatment plants, and two river samples characterized the Milano Metropolitan Area, Italy, were surveyed for SARS-CoV-2 RNA positivity to real time PCR and infectiveness. Moreover, whole genome sequencing and phylogenetic analysis of isolated strains was performed.Raw wastewater samples resulted positive to PCR amplification, while treated water samples were always negative (four and two samples, respectively, sampled in two dates). Moreover, the rate of positivity in raw wastewater samples decreased after eight days, in congruence with the epidemiological trend estimated for the interested provinces. Virus infectiveness was always not significant, indicating the effectiveness of wastewater treatments, or the natural decay of viral vitality, which implied the absence of significant risk of infection from wastewaters. Samples from receiving rivers (two sites, sampled in the same dates as wastewaters) showed in some cases a positivity to PCR amplification, probably due to non-treated discharges, or the combined sewage overflows. Nevertheless, also for rivers vitality was negligible, indicating the absence of sanitary risks. Phylogenetic analysis of genome indicated that the isolated virus belongs to the most spread strain present in Europe and similar to another strain found in Lombardy.

In July 2017, a patient presented colonization with a multidrug-resistant, carbapenemase (KPC-3)-producing Klebsiella pneumoniae isolate. A custom-made, lytic bacteriophage preparation was administered to the patient in December 2017, with subsequent eradication of the microorganism and without adverse effects.

Background: Infective endocarditis (IE) is associated with high rates of mortality. Prolonged treatments with highdose intravenous antibiotics often fail to eradicate the infection, frequently leading to high-risk surgical intervention. By providing a mechanism of antibiotic tolerance, which escapes conventional antibiotic susceptibility profiling, microbial biofilm represents a key diagnostic and therapeutic challenge for clinicians. This study aims at assessing a rapid biofilm identification assay and a targeted antimicrobial susceptibility profile of biofilm-growing bacteria in patients with IE, which were unresponsive to antibiotic therapy. Results: Staphylococcus aureus was the most common isolate (50%), followed by Enterococcus faecalis (25%) and Streptococcus gallolyticus (25%). All microbial isolates were found to be capable of producing large, structured biofilms in vitro. As expected, antibiotic treatment either administered on the basis of antibiogram or chosen empirically among those considered first-line antibiotics for IE, including ceftriaxone, daptomycin, tigecycline and vancomycin, was not effective at eradicating biofilm-growing bacteria. Conversely, antimicrobial susceptibility profile of biofilm-growing bacteria indicated that teicoplanin, oxacillin and fusidic acid were most effective against S. aureus biofilm, while ampicillin was the most active against S. gallolyticus and E. faecalis biofilm, respectively. Conclusions: This study indicates that biofilm-producing bacteria, from surgically treated IE, display a high tolerance to antibiotics, which is undetected by conventional antibiograms. The rapid identification and antimicrobial tolerance profiling of biofilm-growing bacteria in IE can provide key information for both antimicrobial therapy and prevention strategies.