Sannamycin K

A "signal-on" dual-mode aptasensor based on photoelectrochemical (PEC) and electrochemical (EC) signals was established for kanamycin (Kana) assay by using a novel Z-scheme AgBr/AgI-Ag-CNTs composite as sensing platform, an aptamer structure switch, and K3[Fe(CN)6] as photoelectron acceptor and electrochemical signal indicator. The aptamer structure switch was designed to obtain a "signal-off" state, which included an extended Kana aptamer (APT), one immobilized probe (P1), and one blocking probe (P2) covalently linked with graphdiyne oxide (GDYO) nanosheets. P1, P2, and aptamer formed the double helix structure, which resulted in the inhibited photocurrent intensity because of the weak conductivity of double helix layer and serious electrostatic repulsion of GDYO towards K3[Fe(CN)6]. In the presence of Kana, APT specifically bound to the target and dissociated from P1 and P2, and thus, a "signal-on" state was initiated by releasing P2-GDYO from the platform. Based on the sensing platform and the aptamer structure switch, the dual-mode aptasensor realized the linear determination ranges of 1.0 pM-2.0 μM with a detection limit (LOD) of 0.4 pM (for PEC method) and 10 pM-5.0 μM with a LOD of 5 pM (for EC method). The aptasensor displayed good application potential for Kana test in real samples.

The superiority of combination therapy for carbapenem-resistant Gram-negative bacilli (CR-GNB) infections remains controversial. In vitro models may predict the efficacy of antibiotic regimens against CR-GNB. A systematic review and meta-analysis was performed including pharmacokinetic/pharmacodynamic (PK/PD) and time-kill (TK) studies examining the in vitro efficacy of antibiotic combinations against CR-GNB [PROSPERO registration no. CRD42019128104]. The primary outcome was in vitro synergy based on the effect size (ES): high, ES ≥ 0.75, moderate, 0.35 < ES < 0.75; low, ES ≤ 0.35; and absent, ES = 0). A network meta-analysis assessed the bactericidal effect and re-growth rate (secondary outcomes). An adapted version of the ToxRTool was used for risk-of-bias assessment. Over 180 combination regimens from 136 studies were included. The most frequently analysed classes were polymyxins and carbapenems. Limited data were available for ceftazidime/avibactam, ceftolozane/tazobactam and imipenem/relebactam. High or moderate synergism was shown for polymyxin/rifampicin against Acinetobacter baumannii [ES = 0.91, 95% confidence interval (CI) 0.44-1.00], polymyxin/fosfomycin against Klebsiella pneumoniae (ES = 1.00, 95% CI 0.66-1.00) and imipenem/amikacin against Pseudomonas aeruginosa (ES = 1.00, 95% CI 0.21-1.00). Compared with monotherapy, increased bactericidal activity and lower re-growth rates were reported for colistin/fosfomycin and polymyxin/rifampicin in K. pneumoniae and for imipenem/amikacin or imipenem/tobramycin against P. aeruginosa. High quality was documented for 65% and 53% of PK/PD and TK studies, respectively. Well-designed in vitro studies should be encouraged to guide the selection of combination therapies in clinical trials and to improve the armamentarium against carbapenem-resistant bacteria.

Objectives: The aim of this study was to describe antibiotic prescribing patterns and antimicrobial resistance rates in hospitalised children with febrile and afebrile urinary tract infections (UTIs). Methods: Antibiotic prescriptions and antibiograms for neonates, infants and older children with UTI admitted to a general district hospital in Central Greece were evaluated. Data covering a 5-year period were collected retrospectively from the Paediatric Department's Electronic Clinical Archive. Patients were included based on clinical and microbiological criteria. Antimicrobial susceptibility was determined by the Kirby-Bauer disk diffusion method. Results: A total of 230 patients were included in the study. Among 459 prescriptions identified, amikacin (31.2%) was the most common antibiotic prescribed in this population, followed by amoxicillin/clavulanic acid (17.4%) and ampicillin (13.5%). Children received prolonged intravenous (i.v.) treatments for febrile (mean ± S.D., 5.4 ± 1.45 days) and afebrile UTIs (mean ± S.D., 4.4 ± 1.64 days). A total of 236 pathogens were isolated. The main causative organism was Escherichia coli (79.2%) with high reported resistance rates to ampicillin (42.0%), trimethoprim/sulfamethoxazole (26.5%) and amoxicillin/clavulanic acid (12.2%); lower resistance rates were identified for third-generation cephalosporins (1.7%), nitrofurantoin (2.3%), ciprofloxacin (1.4%) and amikacin (0.9%). Klebsiella spp. isolates were highly resistant to cefaclor (27.3%). Conclusion: High prescribing rates for amikacin and penicillins (± β-lactamase inhibitors) and prolonged i.v. treatments were observed. Escherichia coli was highly resistant to ampicillin, whilst third-generation cephalosporins exhibited greater in vitro efficacy. Establishment of antimicrobial stewardship programmes and regular monitoring of antimicrobial resistance could help to minimise inappropriate prescribing for UTIs.