Table 3.

Key recommendations from different recent authoritative guidelines on DTR-PA infections.

IDSA [12]	ESCMID [13]	Italian Guidelines [14]
General approach
Ceftolozane–tazobactam, ceftazidime–avibactam, imipenem–cilastatin–relebactam and cefiderocol as monotherapy are preferred options for the treatment of infections outside of the urinary tract and of the urinary tract; a single dose of an aminoglycoside or cefiderocol may also be used for uncomplicated cystitis; cefiderocol may be used for pyelonephritis and complicated urinary tract infections as well.	Therapy with ceftolozane–tazobactam, if active in vitro, is suggested (conditional recommendation, very low certainty of evidence). Insufficient evidence is available for imipenem–relebactam, cefiderocol and ceftazidime–avibactam.	Ceftolozane/tazobactam and ceftazidime/avibactam are deemed the first-line options for targeted treatment. Imipenem/cilastatin– relebactam and cefiderocol might be potential alternatives, as well as colistin-based therapy (strong recommendation, moderate certainity of evidence).
Monotherapy versus combination therapy
Combination antibiotic therapy is not routinely recommended if in vitro susceptibility to a first-line antibiotic (i.e., ceftolozane–tazobactam, ceftazidime–avibactam, or imipenem–cilastatin–relebactam) has been confirmed.	Lacking evidence, no recommendation can be made for or against the use of combination therapy with the new beta-lactams (ceftazidime–avibactam and ceftolozane–tazobactam). When treating severe infections caused by CRPA with polymyxins, aminoglycosides or fosfomycin, a treatment with two in vitro active drugs is suggested (conditional recommendation, very low certainty of evidence). No recommendation for or against specific combinations can be made.	Combination therapy should not be the routine choice but may be considered on a case-by-case basis, especially upon consultation with infectious diseases specialists. In particular, combination regimens including fosfomycin as companion agent could be considered (conditional recommendation, low certainity of evidence).