In Vitro Activity of Newer and Conventional Antimicrobial Agents, Including Fosfomycin and Colistin, against Selected Gram-Negative Bacilli in Kuwait

Abstract

Limited data are available on susceptibilities of these organisms to some of the recently made accessible antimicrobial agents. The in vitro activities of newer antibiotics, such as, ceftolozane/tazobactam (C/T) and ceftazidime/avibactam (CZA) along with some “older” antibiotics, for example fosfomycin (FOS) and colistin (CL) were determined against selected strains (resistant to ≥3 antimicrobial agents) of Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Minimum inhibitory concentrations (MIC) were determined by Clinical and Laboratory Standards Institute microbroth dilution. 133 isolates: 46 E. coli, 39 K. pneumoniae, and 48 P. aeruginosa were tested. Results showed that E. coli isolates with MIC50/90, 0.5/1 sans-serifμnormalg/mL for CL; 4/32 sans-serifμnormalg/mL for FOS; 0.25/32 sans-serifμnormalg/mL for C/T; 0.25/8 sans-serifμnormalg/mL for CZA, exhibited susceptibility rates of 95.7%, 97.8%, 76.1%, and 89.1%, respectively. On the other hand, K. pneumoniae strains with MIC50/90, 0.5/1 sans-serifμnormalg/mL for CL; 256/512 sans-serifμnormalg/mL for FOS; 2/128 sans-serifμnormalg/mL for C/T; 0.5/128 sans-serifμnormalg/mL for CZA showed susceptibility rates of 92.3%, 7.7%, 51.3%, and 64.1%, respectively. P. aeruginosa isolates with MIC50/90, 1/1 sans-serifμnormalg/mL for CL; 128/128 sans-serifμnormalg/mL for C/T; 32/64 sans-serifμnormalg/mL for CZA presented susceptibility rates of 97.9%, 33.3%, and 39.6%, respectively. Higher MICs were demonstrated against most of the antibiotics. However, CL retained efficacy at low MICs against most of the isolates tested.

Activity of ceftolozane/tazobactam against commonly encountered antimicrobial resistant Gram-negative bacteria in Lebanon

“…However, the MDR P. aeruginosa isolates in our study showed low susceptibility rates to C/T (43%). This rate was higher than that reported from Kuwait (33%) but lower than those reported from other countries, for example: 57% in Turkey and Israel, 63% in Qatar, 89% in Abu Dhabi, 65% -92% in Europe, 79% in USA and 49% -82% in Latin America [3,8,16,[20][21][22][23]. In a recent study from France by Viala et al, the C/T activity for the overall 42 P. aeruginosa was 88% while among those categorized as MDR, it ranged between 73% and 86% [24].…”

“…In our study, the MDR isolates that were also resistant to cefoxitin, and possibly reflect AmpC phenotype, showed low C/T activity (54%) against both EC and KP in this category. This finding was lower than what was reported for the MDR-EC isolates (76%) but close to those reported for the MDR-KP isolates (51%) from Kuwait [20].…”

Microbiological Profile, Biofilm Formation and Antimicrobial Resistance Pattern of Pathogenic Bacteria Isolated from Chronic Ulcerative Lesions

“…In case of E. coli, colistin, amikacin, meropenem and cefotaxime were the most effective antimicrobial agents. Our results were in accordance with the reports of Alfouzan et al 20 and Sader et al 21 . In the present study, it was found that proteus spp.…”

Evaluation of the Synergistic Effect of Amikacin with Cefotaxime against Pseudomonas aeruginosa and Its Biofilm Genes Expression

“…Interpretative reading was used to detect the bactericidal activity of each antibiotic against isolates with cefotaxime MICs of 8-512 and amikacin MICs of 1-64. These data are reinforced by findings from other countries, including Kuwait [37], Canada [38], China [39], and the USA [40].…”