Antimicrobial activity of bioactive glass S53P4 against representative microorganisms causing osteomyelitis - Real-time assessment by isothermal microcalorimetry.

Bioactive glass (BAG) is a synthetic bone substitute with intrinsic antimicrobial properties, used for bone defect filling. We evaluated the antimicrobial activity of two formulations of BAG S53P4 against representative pathogens of osteomyelitis: Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Escherichia coli and Candida albicans. Antimicrobial activity of BAG S53P4 was assessed by isothermal microcalorimetry, a highly sensitive assay measuring metabolic-related microbial heat production in real-time. Standard CFUs-counting was performed in parallel. BAG granules (diameter 500-800 µm) and powder (<45 µm) were evaluated in two concentrations (400 and 800 mg/ml). Isothermal microcalorimetry was performed in glass ampoules containing growth medium, BAG and test microorganism, heat production was measured for 24 h. BAG S53P4 inhibited heat production of most-tested microorganisms with heat reduction of 60%-98% compared to positive control after 24 h of exposure to the highest-tested concentration (800 mg/ml). BAG S53P4 in powder formulation (<45 µm) inhibited more microbial growth than in granule formulation (500-800 µm), with the exception of C. albicans for which both formulations presented similar inhibition rates ranging between 87 % and 97 %. The BAG inhibitory ratios estimated from the variation in the growth rate constants of each microorganism compared to the growth control ranged between 2.55 % and 100 %. Comparable results were obtained by CFUs-counting, with complete reduction in cell viability of most microorganisms after ≤ 24 h of microbial exposure to BAG S53P4 powder. In summary, BAG S53P4 demonstrated efficient inhibition of microbial growth, especially in powder formulation.

Antibiotic Consumption and Resistance during a 3-Year Period in Sicily, Southern Italy.

Antimicrobial resistance (AMR) is one of the biggest issues facing global public health. In 2017, Italy adopted its first National Action Plan on Antimicrobial Resistance 2017-2020, which works through the synergy between national, regional, and local levels. In the framework of a Regional Action Plan on healthcare-associated infections and AMR prevention, the Sicilian Health Authority of the Sicilian Region, Southern Italy, has implemented a surveillance system of antibiotic consumption in hospitals, in the community, and of resistance rates (RRs) in hospital settings. Data on antibiotic consumption and on antibiotic RRs have been collected from 2015 to 2017 from pharmacies and laboratories of participating hospitals and from community, respectively. Data on antibiotic consumption showed that the most consumed antibiotics in hospitals were fluoroquinolones in 2015, penicillin in 2016, and beta-lactams in 2017. From 2015 to 2017, data on Klebsiella pneumoniae showed significant increasing RRs to all antibiotic classes, except to carbapenems. RRs of third-generation cephalosporins and carbapenems Escherichia coli showed significant decreasing trends. RRs of the other microorganisms did not change significantly during the study period. The results from the present study show that in Sicily, the use of antibiotics and RRs for selected microorganisms are at a high level. Immediate strategies are needed to decrease the inappropriate usage of antibiotics and control the spread of AMR.

Epidemiology of Staphylococcus aureus in Italy: First nationwide survey, 2012.

A 3-month epidemiological study to determine the prevalence and antibiotic resistance of Staphylococcus aureus nosocomial infections was performed in 52 centres throughout Italy in 2012. A total of 21,873 pathogens were analysed. The prevalence of S. aureus among all nosocomial pathogens isolated in that period was 11.6% (n=2541), whilst the prevalence of methicillin-resistant S. aureus (MRSA) among the S. aureus was 35.8% (n=910). All tested antimicrobials demonstrated ≥92.2% susceptibility against methicillin-susceptible S. aureus, with the exception of clindamycin (89.7%) and erythromycin (84.2%). Among MRSA, percentages of resistance ranged from 12.6% to >39% for tetracycline, rifampicin, clindamycin and gentamicin; higher percentages were found for erythromycin (65.4%) and fluoroquinolones (72.3-85.8%). Overall, the glycopeptide minimum inhibitory concentration (MIC) distribution showed that 58.3% of strains possessed MICs of 1-2mg/L and few strains were linezolid- or daptomycin-resistant. Molecular characterisation was performed on 102 MRSA selected from Northern, Central and Southern regions. Five major clones were found: Italian/ST228-I (t001-t023-t041-t1686-t3217), 33.3%; USA500/ST8-IV (t008), 17.6%; E-MRSA15/ST22-IVh (t020-t025-t032-t223), 16.7%; USA100/ST5-II (t002-t653-t1349-t2164-t3217-t388), 14.7%; and Brazilian/ST239/241-III (t030-t037), 3.9%. Five PVL-positive CA-MRSA isolates, belonging to USA300 and minor clones, were also identified. In conclusion, this first nationwide surveillance study showed that in Italy, S. aureus infections accounted for 11.6% of all nosocomial infections; MRSA accounted for approximately one-third of the S. aureus isolates and these were multidrug-resistant organisms. Five major MRSA epidemic clones were observed and were inter-regionally distributed, with ST228-SCCmecI becoming predominant.