Phage-Based Control of Methicillin Resistant Staphylococcus aureus in a Galleria mellonella Model of Implant-Associated Infection.

Staphylococcus aureus implant-associated infections are difficult to treat because of the ability of bacteria to form biofilm on medical devices. Here, the efficacy of Sb-1 to control or prevent S. aureus colonization on medical foreign bodies was investigated in a Galleria mellonella larval infection model. For colonization control assays, sterile K-wires were implanted into larva prolegs. After 2 days, larvae were infected with methicillin-resistant S. aureus ATCC 43300 and incubated at 37 °C for a further 2 days, when treatments with either daptomycin (4 mg/kg), Sb-1 (107 PFUs) or a combination of them (3 x/day) were started. For biofilm prevention assays, larvae were pre-treated with either vancomycin (10 mg/kg) or Sb-1 (107 PFUs) before the S. aureus infection. In both experimental settings, K-wires were explanted for colony counting two days after treatment. In comparison to the untreated control, more than a 4 log10 CFU and 1 log10 CFU reduction was observed on K-wires recovered from larvae treated with the Sb-1/daptomycin combination and with their singular administration, respectively. Moreover, pre-infection treatment with Sb-1 was found to prevent K-wire colonization, similarly to vancomycin. Taken together, the obtained results demonstrated the strong potential of the Sb-1 antibiotic combinatory administration or the Sb-1 pretreatment to control or prevent S. aureus-associated implant infections.

In vitro antimicrobial activity against Abiotrophia defectiva and Granulicatella elegans biofilms.

OBJECTIVES: To determine the efficacy of different antibiotics (alone or in combination) against Abiotrophia defectiva and Granulicatella elegans biofilms and to investigate the anti-biofilm activity of gentamicin alone versus blood culture isolates from both species. METHODS: The activity of benzylpenicillin, clindamycin, daptomycin, fosfomycin, gentamicin, levofloxacin and rifampicin against 24-hour-old biofilms of A. defectiva and G. elegans was investigated in vitro by conventional microbiological methods and isothermal microcalorimetry. RESULTS: For planktonic bacteria, the MIC values of tested antibiotics ranged from 0.016 to 64 mg/L, as determined by microcalorimetry. Higher antibiotic concentrations, ranging from 1 to >1024 mg/L, were needed to produce an effect on biofilm bacteria. Gentamicin was an exception as it was active at 1 mg/L against both planktonic and biofilm G. elegans. A synergistic effect was observed when daptomycin was combined with benzylpenicillin, gentamicin or rifampicin against A. defectiva biofilms and when gentamicin was combined with rifampicin or levofloxacin against G. elegans biofilms. A. defectiva clinical isolates displayed greater variability in gentamicin susceptibility as compared with G. elegans strains. CONCLUSIONS: Antimicrobial susceptibility profiles vary widely between Abiotrophia and Granulicatella biofilms, and synergistic effects of the tested antibiotics were heterogeneous. The clinical relevance of these in vitro observations needs to be confirmed in experimental in vivo conditions and human trials, before guidelines for the treatment of A. defectiva and G. elegans infections are established. This study suggests the benefit of further clinical exploration of antibiotic combinations with anti-biofilm effect.

Effectiveness, Tolerability and Prescribing Choice of Antiviral Molecules Molnupiravir, Remdesivir and Nirmatrelvir/r: A Real-World Comparison in the First Ten Months of Use.

In 2022, three antiviral drugs-molnupiravir, remdesivir and nirmatrelvir/ritonavir-were introduced for treatment of mild-to-moderate COVID-19 in high-risk patients. The aim of this study is the evaluation of their effectiveness and tolerability in a real-life setting. A single-center observational study was set up, with the involvement of 1118 patients, with complete follow-up data, treated between the 5th of January and the 3rd of October 2022 at Santa Maria Goretti's hospital in Latina, Central Italy. A univariable and a multivariable analysis were performed on clinical and demographic data and composite outcome, the persistence of symptoms at 30 days and time to negativization, respectively. The three antivirals showed a similar effectiveness in containing the progression of the infection to severe COVID-19 and a good tolerability in the absence of serious adverse effects. Persistence of symptoms after 30 days was more common in females than males and less common in patients treated with molnupiravir and nirmatrelvir/r. The availability of different antiviral molecules is a strong tool and, if correctly prescribed, they can have a significant role in changing the natural history of infection for frail persons, in which vaccination could be not sufficient for the prevention of severe COVID-19.

HBcAb seropositivity is correlated with poor HIV viremia control in an Italian cohort of HIV/HBV-coinfected patients on first-line therapy.

The morbidity and mortality rates of human immunodeficiency virus (HIV)-hepatitis B virus (HBV) coinfection are higher than that of either infection alone. Outcomes and the virological response to antiretrovirals (combination antiretroviral therapy, cART) were explored in HIV/HBV subjects in a cohort of Italian patients treated with cART. A single-center retrospective analysis of patients enrolled from January 2007 to June 2018 was conducted by grouping patients by HBV status and recording baseline viro-immunological features, the history of virological failure, the efficacy of cART in achieving HIV viral undetectability, viral blip detection and viral rebound on follow up. Among 231 enrolled patients, 10 (4.3%) were HBV surface (s) antigen (HBsAg)-positive, 85 (36.8%) were positive for antibodies to HBV c antigen (HBcAb) and with or without antibodies to HBV s antigen (HBsAb), and 136 were (58.9%) HBV-negative. At baseline, HBcAb/HBsAb+/--positive patients had lower CD4+ cell counts and CD4+ nadirs (188 cell/mmc, IQR 78-334, p = 0.02 and 176 cell/mmc, IQR 52-284, p = 0,001, respectively). There were significantly higher numbers of AIDS and non-AIDS events in the HBcAb+/HBsAb+/--positive subjects than in the HBV-negative patients (41.1% vs 19.1%, p = 0.002 and 56.5% vs 28.7%, respectively, p ≤ 0.0001); additionally, HIV viremia undetectability was achieved a significantly longer time after cART was begun in the former than in the latter population (6 vs 4 months, p = 0.0001). Cox multivariable analysis confirmed that after starting cART, an HBcAb+/HBsAb+/--positive status is a risk factor for a lower odds of achieving virological success and a higher risk of experiencing virological rebound (AHR 0.63, CI 95% 0.46-0.87, p = 0.004 and AHR 2.52, CI 95% 1.09-5.80, p = 0.030). HBcAb-positive status resulted in a delay in achieving HIV < 50 copies/mL and the appearance of viral rebound in course of cART, hence it is related to a poor control of HIV infection in a population of coinfected patients.