Successful treatment of Verona integron-encoded metallo-β-lactamase-producing Klebsiella pneumoniae infection using the combination of ceftazidime/avibactam and aztreonam

Evolving resistance landscape in gram-negative pathogens: An update on β-lactam and β-lactam-inhibitor treatment combinations for carbapenem-resistant organisms

Antibiotic resistance has become a global threat as it is continuously growing due to the evolution of β-lactamases diminishing the activity of classic β-lactam (BL) antibiotics. Recent antibiotic discovery and development efforts have led to the availability of β-lactamase inhibitors (BLIs) with activity against extended-spectrum β-lactamases as well as Klebsiella pneumoniae carbapenemase (KPC)-producing carbapenem-resistant organisms (CRO). Nevertheless, there is still a lack of drugs that target metallo-β-lactamases (MBL), which hydrolyze carbapenems efficiently, and oxacillinases (OXA) often present in carbapenem-resistant Acinetobacter baumannii. This review aims to provide a snapshot of microbiology, pharmacology, and clinical data for currently available BL/BLI treatment options as well as agents in late stage development for CRO harboring various β-lactamases including MBL and OXA-enzymes.

Rapid characterization of carbapenem-resistant Enterobacterales by multiplex lateral flow assay and detection of ceftazidime-avibactam-aztreonam synergy

PURPOSE

The choice of antibiotics for treatment of Carbapenem-Resistant Enterobacterales (CRE) is increasing becoming limited due to co-expression of Metallo-beta-lactamases (MBL) along with other carbapenemases in these isolates. The study aimed to investigate the occurrence of CRE and to determine the in-vitro synergy and clinical outcomes of Ceftazidime-Avibactam and Aztreonam combination in CRE infections in adult Intensive Care Units (ICUs).

METHODS

79 CRE isolates recovered from adult ICUs during January to March 2023 were tested by O.K.N.V.I. RESIST-5, a lateral flow multiplex assay for rapid detection of OXA-48-like, NDM, IMP, VIM, and KPC carbapenemases. Ceftazidime-Avibactam MIC was determined by microbroth dilution method and in vitro synergy between Ceftazidime-Avibactam and Aztreonam was assessed by Modified E-test/disc diffusion method for these isolates.

RESULTS

The study revealed 7.5 % occurrence of CRE in our hospital, with high occurrence of NDM (n = 42, 53.1 %) and OXA-48-like (n = 63, 79.7 %) carbapenemase. Production of more than one type of carbapenemases was found in 44 isolates. A total of 57 isolates (72 %) had Ceftazidime-Avibactam resistance and 44 of them displayed Ceftazidime-Avibactam and Aztreonam in-vitro synergy. Successful clinical outcome was observed in two patients who received Ceftazidime-Avibactam and Aztreonam combination therapy for 7 days or more.

CONCLUSIONS

Despite the preponderance of Ceftazidime-Avibactam resistant CRE expressing NDM and OXA-48-like carbapenemase in our hospital, 77.2 % of them displayed in-vitro synergy of Ceftazidime-Avibactam with Aztreonam. It emphasizes the potential therapeutic utility of this combination in CRE strains showing coproduction of MBL and serine carbapenemases. Greater therapeutic potential of Ceftazidime-Avibactam and Aztreonam combination was observed with extended duration of therapy. However, further clinical evidence is needed to establish the efficacy of this combination and consider other factors that influence treatment outcomes.

The threat of multidrug-resistant/extensively drug-resistant Gram-negative respiratory infections: another pandemic

Antibiotic resistance is recognised as a global threat to human health by national healthcare agencies, governments and medical societies, as well as the World Health Organization. Increasing resistance to available antimicrobial agents is of concern for bacterial, fungal, viral and parasitic pathogens. One of the greatest concerns is the continuing escalation of antimicrobial resistance among Gram-negative bacteria resulting in the endemic presence of multidrug-resistant (MDR) and extremely drug-resistant (XDR) pathogens. This concern is heightened by the identification of such MDR/XDR Gram-negative bacteria in water and food sources, as colonisers of the intestine and other locations in both hospitalised patients and individuals in the community, and as agents of all types of infections. Pneumonia and other types of respiratory infections are among the most common infections caused by MDR/XDR Gram-negative bacteria and are associated with high rates of mortality. Future concerns are already heightened due to emergence of resistance to all existing antimicrobial agents developed in the past decade to treat MDR/XDR Gram-negative bacteria and a scarcity of novel agents in the developmental pipeline. This clinical scenario increases the likelihood of a future pandemic caused by MDR/XDR Gram-negative bacteria.