In vitro Bactericidal Activities of Combination Antibiotic Therapies Against Carbapenem-Resistant Klebsiella pneumoniae With Different Carbapenemases and Sequence Types

Abstract

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is becoming increasingly problematic due to the limited effectiveness of new antimicrobials or other factors such as treatment cost. Thus, combination therapy remains a suitable treatment option. We aimed to evaluate the in vitro bactericidal activity of various antibiotic combinations against CRKP with different carbapenemase genotypes and sequence types (STs). Thirty-seven CRKP with various STs and carbapenemases were exposed to 11 antibiotic combinations (polymyxin B or tigecycline in combination with β-lactams including aztreonam, cefepime, piperacillin/tazobactam, doripenem, meropenem, and polymyxin B with tigecycline) in static time-kill studies (TKS) using clinically achievable concentrations. Out of the 407 isolate-combination pairs, only 146 (35.8%) were bactericidal (≥3 log10CFU/mL decrease from initial inoculum). Polymyxin B in combination with doripenem, meropenem, or cefepime was the most active, each demonstrating bactericidal activity in 27, 24, and 24 out of 37 isolates, respectively. Tigecycline in combination with β-lactams was rarely bactericidal. Aside from the lower frequency of bactericidal activity in the dual-carbapenemase producers, there was no apparent difference in combination activity among the strains with other carbapenemase types. In addition, bactericidal combinations were varied even in strains with similar STs, carbapenemases, and other genomic characteristics. Our findings demonstrate that the bactericidal activity of antibiotic combinations is highly strain-specific likely owing to the complex interplay of carbapenem-resistance mechanisms, i.e., carbapenemase genotype alone cannot predict in vitro bactericidal activity. The availability of WGS information can help rationalize the activity of certain combinations. Further studies should explore the use of genomic markers with phenotypic information to predict combination activity.

In Vitro Susceptibility to Ceftazidime-Avibactam and Comparator Antimicrobial Agents of Carbapenem-Resistant Enterobacterales Isolates

“…Carbapenemase genotypic characterization was performed using whole-genome sequencing as previously described [ 22 ]. In brief, genomic deoxyribonucleic acid (DNA) was extracted and purified from overnight bacterial cultures with the DNeasy blood and tissue kit (Qiagen GmbH, Hilden, Germany) according to the manufacturer’s protocol.…”

Current state of antimicrobial stewardship in organ transplantation in Singapore

“…The team has long been interested in developing individualized combination therapies -christened in vitro antibiotic combination testing -for extensively drug-resistant organisms. [85][86][87][88] It is fortuitous that in our hospital, such research is undertaken by a team including a few ASP pharmacists. The ASP pharmacist rounding with the TID physician can act as a bridge, recruiting patients with difficult-to-treat MDROs into studies (fortunately a rare occurrence).…”

“…In our hospital, there is a well‐established research team led by ID‐trained pharmacists, some of whom are members of the ASP. The team has long been interested in developing individualized combination therapies ‐ christened in vitro antibiotic combination testing – for extensively drug‐resistant organisms 85–88 …”

In vitro Activity of Cefepime/Avibactam Against Carbapenem Resistant Klebsiella pneumoniae and Integrative Metabolomics-Proteomics Approach for Resistance Mechanism: A Single-Center Study

“…15 Previous studies have found that cefepime in combination with polymyxin B demonstrated bactericidal activity in 24 out of 37 isolates. 19 And FEP/AVI exhibited potency against CTX-M-15 producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae), 7,20 but the antibacterial activity and resistance mechanism of this combination has not been extensively studied. Therefore, this study compared the antibacterial effects of CAZ/AVI and FEP/AVI against CRKP, and explored the resistance mechanism of FEP/AVI through proteomics and metabolomics studies.…”