Assessment of combination therapy in BALB/c mice injected with carbapenem-resistant Enterobacteriaceae strains

Abstract

Monotherapeutic options for carbapenem resistant infections are limited. Studies suggest that combination therapy may be associated with better outcomes than monotherapies. However, this is still controversial. This study assessed, the efficacy of combination therapy against carbapenem resistant Enterobacteriaceae harboring singly various extended spectrum beta lactamase or carbapenemase encoding genes. Thus, four isolates harboring either blaCTXM-15, blaCTXM-15 and blaOXA-48, blaNDM-1, or blaKPC-2 genes were selected for testing. Minimal inhibitory concentration was determined by broth dilution method. Gene transcript levels on single and combined treatments were done in vitro and in vivo by qRT-PCR. Assessment of treatments was done in BALB/c mice according to a specific protocol. As such, the qRT-PCR revealed a significant decrease of transcript levels in all isolates upon using rifampicin or tigecycline, singly or in combination with colistin. However, variable levels were obtained using colistin singly or in combination with meropenem or fosfomycin. In vivo assessment showed that all combinations used were effective against isolates harboring blaCTXM-15, blaOXA-48, and blaNDM-1. Conversely, the most significant combination against the isolate harboring blaKPC-2 gene was colistin with either carbapenem, fosfomycin, or kanamycin. As a conclusion, combination therapy selected based on the type of carbapenemase produced, appeared to be non-toxic and might be effective in BALB/c mice. Therefore, the use of a rationally optimized combination therapy might lead to better results than monotherapy, however, clinical trials are needed for human consumption.

Antimicrobial agents active against carbapenem-resistant Escherichia coli and Klebsiella pneumoniae isolates in Lebanon

“…Studies at our medical center since 2008 have been addressing molecular characterizations, resistance mechanisms, genes involved, and other aspects of CR Ec and Kp isolates [9,10,[12][13][14]. The first CRE detected in Lebanon was a K. pneumoniae recovered from a 7year-old female child, which was characterized by PCR experiments using primers for multiple β-lactamase and carbapenemase genes: TEM, SHV, CTX-M, GES, KPC, IMI, OXA-1 ⁄ 2 ⁄ OXA-10 ⁄ 18, OXA-23 ⁄ 58, IMP, VIM, SPM, GIM and SIM.…”

“…We also assessed the effects of antimicrobial combination therapy against bacteria with different CR genes using BALB/c mice [13]. The mice were injected with carbapenem-resistant Enterobacteriaceae strains, harboring either bla CTXM-15 , bla CTXM-15 and bla OXA-48 , bla NDM-1 , or bla KPC-2 genes.…”

“…Conversely, the most significant combination against the isolate harboring the bla KPC-2 gene was colistin with either carbapenem, fosfomycin, or kanamycin. Essentially, the findings indicated that combination therapy selected based on the type of carbapenemase produced, appeared to be non-toxic and effective in BALB/c mice [13]. Therefore, an approach based on gene detection may be useful to extrapolate for human use, as a step towards optimizing combination therapy and antimicrobial stewardship when in treating patients with CRE infections.…”

“…In Lebanon, similar problems and challenges have been encountered since CRE pathogens were introduced in this country several years ago [9,10]. As a result, several studies have been conducted to describe the phenotypic and molecular features of CR E. coli and K. pneumoniae in this country [5,[11][12][13][14][15].…”

In vivo monitoring of therapeutic efficacy and virulence profile by bioluminescent Klebsiella pneumoniae.

“…We wanted to test whether we can use optical diagnostic imaging to monitor the efficacy of current and novel therapeutics noninvasively, and since we have demonstrated that the JSKP001 strain is sensitive to meropenem, we decided to utilize this antibiotic as a proof of concept to investigate this question. Meropenem is an important drug for treating K. pneumoniae infections including pneumonia [43,87,118,[265][266][267]. Therefore, we decided to investigate if meropenem is capable of resolving the respiratory disease and if the direct impact of the therapeutic on bacterial viability can be monitored in vivo using BLI.…”