KPC-producing Klebsiella pneumoniae gut decolonisation following ceftazidime/avibactam-based combination therapy: A retrospective observational study

In vitro mimicry of in vivo KPC mutations by ceftazidime-avibactam: phenotypes, mechanisms, genetic structure and kinetics of enzymatic hydrolysis

Ceftazidime-avibactam (CZA) is employed for the treatment of infections caused by Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-KP). Resistance to CZA is frequently linked to point mutations in the blaKPC. We conducted in vitro simulations of in vivo blaKPC mutations using CZA. Four pre-therapy KPC-KP isolates (K1, K2, K3, and K4) were evaluated, all initially exhibited susceptibility to CZA and produced KPC-2. The crucial distinction was that following CZA treatment, the blaKPC-2 mutated in K1, K2, and K3, rendering them resistant to CZA, while K4 achieved microbiological clearance, and blaKPC-2 remained unaltered. The induction assay identified various blaKPC-2 variants, including blaKPC-25, blaKPC-127, blaKPC-100, blaKPC-128, blaKPC-137, blaKPC-138, blaKPC-144 and blaKPC-180. Our findings suggest that the resistance of KPC-KP to CZA primarily results from the emergence of KPC variants, complemented by increased blaKPC expression. A close correlation exists between avibactam concentration and the rate of increased CZA minimum Inhibitory concentration, as well as blaKPC mutation. Inadequate avibactam concentration is more likely to induce resistance in strains against CZA, there is also a higher likelihood of mutation in the blaKPC-2 and the optimal avibactam ratio remains to be determined. Simultaneously, we selected a blaKPC-33-producing K. pneumoniae strain (mutated from blaKPC-2) and induced it with imipenem and meropenem, respectively. The blaKPC-2 was detected during the process, indicating that the mutation is reversible. Clinical use of carbapenems to treat KPC variant strains increases the risk of infection, as the gene can mutate back to blaKPC-2, rendering the strain even more cross-resistant to carbapenems and CZA.

Decolonization of drug-resistant Enterobacteriaceae carriers: A scoping review of the literature

The ESCMID-EUCIC guideline on decolonization of multidrug-resistant Gram-negative bacteria carriers does not recommend routine decolonization and highlights the necessity of well-powered and designed randomized clinical trials. Based on this limited evidence, we decided to conduct a scoping review with the aim of describing and discussing the last published studies investigating the efficacy and safety of decolonization therapies in drug-resistant Enterobacteriaceae carriers. Studies published in PubMed from January 1, 2017 to December 28, 2021 were retrieved. A PICO (population, intervention, comparator, outcome) framework was used for article selection as follows: Population defined as any patient of any age in any setting with screening sample yielding for drug-resistant Enterobacteriaceae; Intervention defined as any decolonization; Controls defined as patients receiving no intervention (spontaneous decolonization) or a different decolonization therapy; Outcomes defined as a microbiological, clinical, epidemiological and adverse event. A total of 679 records were initially identified, of which 647 were excluded because they were not related to decolonization therapies. Other 18 records were excluded because not related to our aims, target bacteria, or study design. A total of 12 clinical studies were included, of which 4 were randomized clinical trials and 8 were non-randomized studies. The majority of studies evaluated selective decontamination of the digestive tract or selective oropharyngeal decontamination regimens. Selected studies were characterized by high heterogeneity. Further high-quality studies with proper design and sample size calculation are warranted.

Gastrointestinal colonization by OXA-48-producing Enterobacterales: risk factors for persistent carriage

Carbapenem-resistant Enterobacterales (CRE) infections are a major health problem. Intestinal colonization is a key factor in developing infection. However, factors associated with persistent colonization by CRE are unknown. The aim of the study was to identify factors associated with persistent CRE gut colonization. This is a retrospective, single-centre, observational study of adult patients with CRE gut colonization between January 2015 and January 2020. Epidemiologic characteristics, comorbidities, infectious events, duration of hospitalization and antimicrobial treatment received in the follow-up period were collected. Colonization was defined as isolation in at least 2 rectal swab culture samples of CRE. Decolonization was defined as 3 negative rectal swab cultures or 2 negative cultures and a negative molecular test. A cohort of 86 patients with CRE gut colonization was selected: 44 patients with spontaneous decolonization (DC) and 42 patients with persistent colonization (PC). The mean follow-up period was 24 months (IQR 14-33) in the DC group vs. 25 months (IQR 16-36) in the PC group (p = 0.478). Patient characteristics were similar between both groups. Colonization by other MDR microorganisms was high (44 patients, 51%) and slightly more common in the PC group (PC 60% vs. DC 43%, p = 0.139). The use of ceftazidime-avibactam was more common among the PC group (PC 33% vs. DC 14%, p = 0.041). We observed a higher percentage of antimicrobial therapy in the previous 30 days (PC 68% vs. DC 57%, p = 0.371) and 90 days (PC 81% vs. DC 82%, p = 0.353) in the PC group. Multivariable analysis showed that patients that have received ceftazidime-avibactam therapy (OR 4.9 95% CI [1.45-16.39], p = 0.010), and those colonized by other MDR microorganisms (OR 2.5, 95% CI [0.96-6.25], p = 0.060) presented a higher risk of PC. Ceftazidime-avibactam use and colonization by other MDR microorganisms might be associated with CRE persistent gut colonization.

Update on the role of ceftazidime-avibactam in the management of carbapenemase-producing Enterobacterales

Ceftazidime-avibactam is a novel combination of a known cephalosporin and a non-β-lactam/β-lactamase inhibitor that has been approved for the treatment of complicated intra-abdominal and urinary tract infections, hospital-acquired pneumonia as well as Gram-negative infections with limited treatment options in Europe. Since its approval, it has been used in patients with infections due to carbapenem-resistant bacteria, in many occasions as off-label indication or salvage therapy, with promising clinical and microbiological cure rates. Emergence of resistance during therapy to this new combination has already been described, which is a matter of concern. A rational use of these new therapeutic options is critical in the multidrug resistance era. The current review focuses on the clinical experience in real life of ceftazidime-avibactam use in the treatment of carbapenemase-producing Enterobacterales.