Genomic characterization of Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) strains circulating in three university hospitals in Northern Italy over three years.

OBJECTIVES: Genomic surveillance of Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) is crucial for virulence, drug-resistance monitoring, and outbreak containment. METHODS: Genomic analysis on 87 KPC-Kp strains isolated from 3 Northern Italy hospitals in 2019-2021 was performed by whole genome sequencing (WGS), to characterize resistome, virulome, and mobilome, and to assess potential associations with phenotype resistance and clinical presentation. Maximum Likelihood and Minimum Spanning Trees were used to determine strain correlations and identify potential transmission clusters. RESULTS: Overall, 15 different STs were found; the predominant ones included ST307 (35, 40.2%), ST512/1519 (15, 17.2%), ST20 (12, 13.8%), and ST101 (7, 8.1%). 33 (37.9%) KPC-Kp strains were noticed to be in five transmission clusters (median number of isolates in each cluster: 5 [3-10]), four of them characterized by intra-hospital transmission. All 87 strains harbored Tn4401a transposon, carrying blaKPC-3 (48, 55.2%), blaKPC-2 (38, 43.7%), and in one case (1.2%) blaKPC-33, the latter gene conferred resistance to ceftazidime/avibactam (CZA). Thirty strains (34.5%) harbored porin mutations; of them, 7 (8.1%) carried multiple Tn4401a copies. These strains were characterized by significantly higher CZA minimum inhibitory concentration compared with strains with no porin mutations or single Tn4401a copy, respectively, even if they did not overcome the resistance breakpoint of 8 ug/mL. Median 2 (IQR:1-2) virulence factors per strain were detected. The lowest number was observed in ST20 compared to the other STs (p<0.001). While ST307 was associated with infection events, a trend associated with colonization events could be observed for ST20. CONCLUSIONS: Integration of genomic, resistance score, and clinical data allowed us to define a relative diversification of KPC-Kp in Northern Italy between 2019 and 2021, characterized by few large transmission chains and rare inter-hospital transmission. Our results also provided initial evidence of correlation between KPC-Kp genomic signatures and higher MIC levels to some antimicrobial agents or colonization/infection status, once again underlining WGS's importance in bacterial surveillance.

Phase IV study of bevacizumab in combination with infusional fluorouracil, leucovorin and irinotecan (FOLFIRI) in first-line metastatic colorectal cancer.

BACKGROUND: Bevacizumab (Avastin) significantly improves overall survival (OS) and progression-free survival (PFS) when combined with first-line irinotecan (IFL) plus bolus 5-fluorouracil (5-FU) and leucovorin (LV) in patients with metastatic colorectal cancer (CRC). This open-label, phase IV trial evaluated the efficacy and safety of first-line bevacizumab in combination with IFL and infusional 5-FU/LV (FOLFIRI). METHODS: Two-hundred and nine treatment-naïve metastatic CRC patients were enrolled and received bevacizumab and FOLFIRI every 2 weeks. Treatment was continued until disease progression. The primary objective was PFS, with additional determinations of OS, response and toxicity. RESULTS: Median PFS was 11.1 months and is comparable to that observed in published phase III and community-based trials using first-line bevacizumab plus FOLFIRI, and to phase III trials using bevacizumab in combination with bolus 5-FU/LV plus IFL. Median OS was 22.2 months. Overall response rate was 53.1% and the disease control rate 85.6%. Most adverse events were grade 1/2 and were manageable. The most common grade 3/4 adverse events (> or =10%) were neutropenia, venous thromboembolic events, diarrhea, and fatigue. CONCLUSION: Bevacizumab combined with first-line FOLFIRI is an effective and well-tolerated therapy option for patients with metastatic CRC.