Overcoming resistance barriers: Using the salvage therapy of Ceftazidime-Avibactam and Aztreonam for difficult-to-treat gram-negative infections at a tertiary care hospital in Karachi-A retrospective cohort pilot. - Sarfaraz, Samreen; Zafar, Syeda Mahnoor; Siddiqui, Nabeel Ahmed; Hanif, Muhammad Hamid; Hussain, Zahid (Pakistan Journal of Medical Sciences, 2026)