Isolates Of Gram-negative Pathogens Research Articles

In vitro activity of cefiderocol and comparators against isolates of Gram-negative pathogens from a range of infection sources: SIDERO-WT-2014–2018 studies in Italy

Antimicrobial resistance, particularly carbapenem resistance, in Gram-negative pathogens poses a significant healthcare threat. Carbapenem resistance rates in Italy are among the highest in Europe. We report the in vitro activity of cefiderocol, a novel siderophore cephalosporin, and comparator antibiotics against Gram-negative isolates from Italy as part of the SIDERO-WT studies. Isolates were collected between 2014 and 2018. Minimum inhibitory concentrations (MICs) were determined using International Organization for Standardization and EUCAST guidelines. Antimicrobial susceptibilities were interpreted using EUCAST breakpoints; pharmacodynamic/pharmacokinetic breakpoints were used if EUCAST breakpoints were not specified. The 2472 isolates [1545 (62.5%) Enterobacterales and 927 (37.5%) non-fermenters] represented a range of infection sources, including nosocomial pneumonia (902; 36.5%), complicated urinary tract infection (374; 15.1%), bloodstream infection (596; 24.1%), complicated intra-abdominal infection (257; 10.4%) and other infection sources (343; 13.9%). Cefiderocol was active against the majority of isolates, regardless of infection source (susceptibility, 94.2-97.3%). A high proportion of non-fermenters (97.6%) and Enterobacterales (95.6%) were cefiderocol-susceptible, although susceptibility was lower in Klebsiella pneumoniae (88.1%). Susceptibility to cefiderocol was significantly (P < 0.01) greater than comparators overall (96.4% vs. 71.3-81.6%) and in non-fermenters (97.6% vs. 44.3-90.3%) across infection sources. Overall 612/2472 isolates (24.8%) were meropenem-resistant (MIC > 8 mg/L), comprising 516/927 (55.7%) non-fermenters and 96/1545 (6.2%) Enterobacterales. Cefiderocol (499/516; 96.7%) activity was greater than colistin (440/516; 85.3%), ceftazidime/avibactam (123/516; 23.8%) and ceftolozane/tazobactam (89/516; 17.2%) in meropenem-resistant non-fermenter isolates. Susceptibility to cefiderocol was significantly greater than meropenem, colistin, ceftazidime/avibactam and ceftolozane/tazobactam overall, regardless of infection source.

In vitro activity of cefiderocol and comparators against isolates of Gram-negative pathogens from a range of infection sources: SIDERO-WT-2014-2018 studies in France.

ObjectivesOver recent years, France has experienced an increase of infections caused by carbapenem-resistant Gram-negative (GN) pathogens. Cefiderocol is approved in Europe for the treatment of aerobic GN infections in adults with limited treatment options. This study evaluated the in vitro activity of cefiderocol and comparators against GN clinical isolates from France.MethodsMICs were determined by broth microdilution, according to International Organization for Standardization guidelines. Cefiderocol was tested using iron-depleted CAMHB. Susceptibility rates were based on EUCAST breakpoints. In the absence of a species-specific breakpoint, pharmacokinetic/pharmacodynamic breakpoints were used.ResultsOf 2027 isolates, 1344 (66.3%) were Enterobacterales and 683 (33.7%) were non-fermenters. The most common pathogen was Pseudomonas aeruginosa (16.8%), followed by Escherichia coli (16.0%), Klebsiella pneumoniae (13.1%), Acinetobacter baumannii (7.9%) and Stenotrophomonas maltophilia (5.1%). Isolates represented a range of infection sources including nosocomial pneumonia (33.6%), complicated urinary tract infection (24.3%), bloodstream infection (13.1%) and complicated intra-abdominal infection (18.0%). In total, 135/2027 (6.7%) isolates were meropenem resistant (MIC >8 mg/L); 133/135 (98.5%) were non-fermenters. Overall, 1330/1344 (99.0%) Enterobacterales and 681/683 (99.7%) non-fermenters were cefiderocol susceptible, including 100% of meropenem-resistant S. maltophilia (n = 98) and P. aeruginosa (n = 18) isolates. Susceptibility to cefiderocol was significantly higher (P < 0.01) in nosocomial pneumonia isolates (681/682 [99.9%]) than susceptibility to meropenem (586/682 [85.9%]), ceftolozane/tazobactam (593/682 [87.0%]), ceftazidime/avibactam (612/682 [89.7%]) and colistin (538/682 [78.9%]).ConclusionsCefiderocol demonstrated high in vitro susceptibility rates against a wide range of Gram-negative pathogens, including meropenem-resistant strains, and was significantly more active than comparators against pneumonia isolates.

In Vitro Antibacterial Activity of Rheum ribes Extract Obtained from Various Plant Parts Against Clinical Isolates of Gram-Negative Pathogens

Rheum ribes is among the Polygonaceae family which is endemic in Iran and a few neighboring countries. In this investigation, antibacterial effects of root, stalk and leaves extracts of Rheum ribes on a few common clinical isolates of gram negative pathogens were studied, using the cup plate and paper disc methods. Gram negative microorganisms studied were Escherichia coli, Klebsiella pneumoniae, Proteus spp., Pseudomonas aeruginosa and Neisseria gonorrhoeae. For examination of pathogenic microorganisms in the cup plate and disc diffusion method, methanolic extracts of different plant parts at concentrations of 250 and 500 micrograms per cup or disc, were used. The root and leaves extracts have demonstrated significant antibacterial activities in both methods. However, stalk extracts showed a lower degree of antibacterial activity than the root and leaves extracts. Generally, the extracts showed a broad spectrum of activity, although they were more effective against P. aeruginosa and Proteus spp. in comparison with the positive control. The results suggested that extracts of Rheum ribes could be effectively used against clinical isolates.