PubMed · 8694715
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M H Haimann, H Weiss, J Miller. 1996. The Endophthalmitis Vitrectomy Study.. https://doi.org/10.1001/archopht.1996.01100140233030
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OBJECTIVE: This study aims to assess the in vitro drug susceptibility of various Carbapenemase-Producing Enterobacteriaceae (CPE) genotypes and elucidate the underlying mechanisms of amikacin resistance. METHODS: A total of 72 unique CPE strains were collected from the Second Hospital of Jiaxing between 2019 and 2022, including 51 strains of Klebsiella pneumoniae, 11 strains of Escherichia coli, 6 strains of Enterobacter cloacae, 2 strains of Klebsiella aerogenes, 1 strain of Citrobacter freundii, and 1strain of Citrobacter werkmanii. Among these strains, 24 carried blaKPC gene, 20 carried blaNDM gene, 23 carried blaOXA-48-like gene, and 5 carried both blaKPC and blaNDM. We measured the in vitro activity of amikacin and other common antibiotics. Strains carrying blaOXA-48-like gene were selected for whole genome sequencing (WGS) via next-generation sequencing to identify genes related to antimicrobial resistance (AMR) and virulence factor (VF). RESULTS: Out of the 72 CPE strains tested, 41.7% exhibited resistance to amikacin. The drug resistance rates for K. pneumoniae, E. coli, and Enterobacter spp. were 51.0%, 27.3%, and 10.0%, respectively. The majority of the CPE strains (> 90%) displayed resistance to cephalosporins and carbapenems, while most of them were sensitive to polymyxin B and tigecycline (97.2% and 94.4%). The amikacin resistance rate was 100% for strains carrying blaOXA-48, 20.8% for those with blaKPC, 5.0% for those with blaNDM, and 20.0% for those with both blaKPC and blaNDM. These differences were statistically significant (P < 0.05). Through sequencing, we detected aminoglycoside resistance genes rmtF and aac(6')-Ib, VF genes iucABCD and rmpA2 in OXA-48-producing multidrug resistance and highly virulent strains. These genes were located on a IncFIB- and IncHI1B-type plasmid, respectively. Both plasmids were highly homologous to the plasmid from OXA-232 strains in Zhejiang province and Shanghai province. Integration of these resistance genes into the IncFIB plasmid, facilitated by the IS6 and/or Tn3 transposons, resulted in OXA232-producing K. pneumoniae with amikacin resistance. CONCLUSION: This study identified significant amikacin resistance in CPE strains, particularly in those carrying the blaOXA-48 gene. Resistance genes rmtF and aac(6')-Ib were identified on plasmids. These results highlight the need for careful monitoring of amikacin resistance.
We conducted a randomized multicenter study to compare the efficacy and safety of two antibiotic regimens (cefepime [2 g b.i.d.] plus amikacin or ceftazidime [2 g t.i.d.] plus amikacin) as first-line therapy for fever in patients with hematologic malignancies and neutropenia. A total of 353 patients were randomized according to a 2:1 (cefepime:ceftazidime) ratio. Two hundred-twelve patients in the cefepime group and 107 in the ceftazidime group (90% of all patients) were evaluable for efficacy. The polymorphonuclear neutrophil count was < 100/mm3 on enrollment for 70% of the patients. The mean duration of neutropenia was 26 days. The efficacy in both study arms was comparable, although a trend in favor of cefepime was seen in terms of therapeutic success (response rate, 27% vs. 21% for the ceftazidime group). The overall response rate after glycopeptides were added to the regimens was 60% for the cefepime group and 51% for the ceftazidime group; the bacterial eradication rates were 81% vs. 76%, respectively, and the rates of new bacterial infections were 14% vs. 18%, respectively. We conclude that the combination cefepime/amikacin is at least as effective as the reference regimen of ceftazidime/amikacin in this setting.
The pharmacodynamic effects of amikacin, imipenem, ofloxacin, rifampin, and vancomycin were studied on the slime-producing, oxacillin-resistant strain Staphylococcus epidermidis ATCC 35984 growing in Mueller Hinton broth or, in order to inhibit growth, incubated in phosphate-buffered saline. The investigated parameters were postantibiotic effect (PAE) and control-related effective regrowth time (CERT), which were determined by bioluminescence assay of bacterial ATP. PAE describes the delayed regrowth after drug removal, and CERT describes the combined effects of initial change in bacterial density during antibiotic exposure and delayed regrowth after drug removal. In growth cultures, PAE and CERT were drug concentration dependent for all antibiotics. The length of the PAE and CERT in the growing cultures were as follows: ofloxacin > rifampin > amikacin > vancomycin > imipenem. Imipenem combined with amikacin and vancomycin, respectively, induced a synergistic effect against growing cultures. In nongrowing cultures rifampin was the only drug that induced strong concentration-dependent effects. The combination of drugs induced no synergistic effects against nongrowing bacteria.