In vitro activity of cefoperazone and cefoperazone-sulbactam against carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa
In vitro activity of cefoperazone and cefoperazone-sulbactam against carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa
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Chih-Cheng Lai,1 Chi-Chung Chen,2,3 Ying-Chen Lu,3 Yin-Ching Chuang,2,4 Hung-Jen Tang5,6 1Department of Intensive Care Medicine, Chi Mei Medical Center, Liouying, Tainan, Taiwan; 2Department of Medical Research, Chi Mei Medical Center, Tainan, Taiwan; 3Department of Food Science, National Chiayi University, Chiayi, Taiwan; 4Department of Internal Medicine, Chi Mei Medical Center, Liouying, Tainan, Taiwan; 5Department of Medicine, Chi Mei click here Medical Center, Tainan, Taiwan; 6Department of Health and Nutrition, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan Background: This study aimed to investigate the in vitro activity of cefoperazone–sulbactam against carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa, and to evaluate the antibiotic resistance mechanisms of these bacteria.Materials and methods: In total, 21 isolates of carbapenem-resistant P.aeruginosa and 15 isolates of carbapenem-resistant A.
baumannii with different pulsed-field gel electrophoresis types were collected for assessment of the in vitro antibacterial activities of cefoperazone and cefoperazone–sulbactam and the associated resistance mechanisms of the bacteria.Results: For carbapenem-resistant P.aeruginosa, the minimum inhibitory concentration (MIC) value and antibiotic susceptibility rate were similar for cefoperazone and cefoperazone–sulbactam (at 1:1 and 2:1 ratios).
In contrast, for carbapenem-resistant A.baumannii, the MIC values, including the MIC range, MIC that inhibited 50% of isolates (MIC50) and MIC that inhibited 90% of isolates (MIC90), were reduced after treatment with sulbactam and cefoperazone.We screened resistance genes, including VIM-2, OXA-2 and OXA-10, in 21 carbapenem-resistant P.
aeruginosa isolates.Only one (4.8%) of the isolates showed expression of VIM-2, and neither the OXA-2 nor the OXA-10 gene was detected.
However, 20 (95.2%) isolates among the carbapenem-resistant P.aeruginosa isolates selected for oprD sequencing showed the phenomenon of nucleotide substitution or deletion.
Among 15 carbapenem-resistant A.baumannii isolates, we found that ten (66.7%) isolates had concomitant expression of the OXA-23 and ISAba1-OXA-23 genes, and six (40.
0%) isolates had expression of the OXA-24-like gene.All 15 isolates had OXA-51-like gene expression, and only 1 (6.7%) isolate had ISAba1-OXA-51-like gene expression.
None of the isolates contained the IMP-1, IMP-8, KPC, NDM, VIM-1 or OXA-48 genes.Conclusion: The in vitro antibacterial activity of cefoperazone against carbapenem-resistant A.baumannii can be enhanced by adding sulbactam to cefoperazone, but the addition does not affect carbapenem-resistant P.
aeruginosa.This significant difference can be explained by the different resistance mechanisms of carbapenem-resistant merrick backcountry wet cat food A.baumannii and P.
aeruginosa.Keywords: cefoperazone–sulbactam, Acinetobacter baumannii, Pseudomonas aeruginosa.