Background
Treatment of pandrug-resistant isolates often necessitates combination therapy. Checkerboard synergy and time-killing assay tests were performed to evaluate the benefits of a triple combination with meropenem, ertapenem, and colistin against 10 colistin-resistant K. pneumoniae clinical isolates harboring different β-lactamases. (blaOXA-48, blaNDM).
Materials and methods
In this study, ertapenem and meropenem (ERT/MEM), meropenem and colistin (MEM/COL), ertapenem, meropenem and colistin (ERT/MEM/COL) combinations were tested using checkerboard techniques and time-kill assays of each antibiotic alone and in combination against 10 colistin-resistant clinical K. pneumoniae isolates. An analysis of K. pneumoniae isolate B6 using a scanning electron microscope revealed morphologic changes in the cell surface after treatment with each antibiotic both alone and in combination. The whole genome of K. pneumoniae KPNB1 was sequenced using an Ion Torrent PGM sequencer.
Results
According to the checkboard results, synergistic combinations were observed with ertapenem/meropenem (5/10 isolates), meropenem/colistin (7/10) and ertapenem/meropenem/colistin (9/10); no antagonism was observed for all combinations. For the time-kill assay results; synergism and bactericidal effects were observed with meropenem/colistin (10/10) and with ertapenem/meropenem/colistin (10/10) combinations, and an indifference effect was observed with the ertapenem and meropenem (10/10) combination. Strain number 1 was found 100% identical to Klebsiella pneumoniae subsp. pneumoniae HS11286 according to the outcomes of complete genome sequence analysis, and the strain carried the genes blaOXA-181, blaCTXM-15, blaNDM, arr-3, aac (6′)-Ib-cr, rmtF, and catB1.
Conclusion
Using double carbapenem antibiotics with colistin could be a potential alternative to treat colistin and carbapenem-resistant K. pneumoniae. The present study is the first Turkish report of OXA–181-type carbapenemase causing colistin resistance.
Our findings indicated that tetanus antibody values were under the protective level for most adults over 40 years of age, and vaccination programs directed at the adult population should be developed.
We describe a case of Acremonium falciforme fungemia under treatment of fluconazole. A. falciforme is a common saprophyte. This fungus has been isolated from a patient's specimen, and the organism may have contributed to his death.
To our knowledge, this is the first identification of blaNDM in E. cloacae isolates in Turkey. These findings describe an interhospital spread of CRKP-producing OXA-48 and NDM carbapenemases that started in 2011. Continuous monitoring is necessary to better understand their dissemination in the hospital, which probably occurred as a result of transmission from an environmental reservoir. These findings emphasize the need for intensive surveillance and precautions.
An outbreak of Candida glabrata fungemia that was thought to be associated with bottles used for milk feeds occurred at our children's infectious diseases clinic. This cluster of cases was investigated using a case-control study. Isolates were identified by conventional methods and karyotyped using pulsed-field gel electrophoresis (PFGE) of genomic DNA. Potential risk factors for nine hospitalized children with candidemia and 14 controls were long-term hospitalization and treatments with more than two antibiotics. Electrophoretic karyotyping showed a single chromosomal pattern for these outbreak isolates and, in addition, they all had the same antifungal susceptibility results. These findings suggest that clonal dissemination of a single strain was responsible for this outbreak. Karyotyping by PFGE appears to be a useful molecular typing method for strains of C. glabrata.
Both IC assays and BCT tests have good performance and are easy to perform, rapid, simple to interpret, and highly sensitive. We suggest that BCT can be used initially as an accurate, inexpensive, and rapid phenotypic confirmation test to identify Class A, B, and D carbapenemases in the routine diagnostic microbiology laboratory, thus allowing the detection of carbapenemase activity directly from bacterial cultures.
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