Background and Objectives: Carbapenems are considered the last resort to treat several infections, particularly in intensive care units (ICUs). However, increasing carbapenem resistance is problematic because it leads to high morbidity and mortality rates. This study aimed to determine the rate of carbapenem resistance among Gram-negative bacteria collected from patients in ICUs and to identify their resistance mechanisms using phenotypic and genotypic methods. Materials and Methods: Antimicrobial susceptibility testing was carried out using the disc diffusion method among 180 Gram-negative bacterial isolates. Productions of carbapenemases, metallo-beta-lactamases (MBLs) and the harboring of carbapenemase-encoding genes, were detected in 40 selected carbapenem-resistant Gram-negative bacteria (CR-GNB). Results: Of 40 selected CR-GNB isolates, 28 (70%), and 20 (50%) isolates were phenotypically positive for carbapenemase, and MBL production, respectively. Furthermore, 22 (55%) showed amplification of one or more of the carbapenemase-en- coding genes, including blaNDM-1, blaVIM-2, and blaOXA-48. This study described the first emergence of NDM-1 producing Kleb- siella oxytoca in Egyptian ICUs. Conclusion: High incidence of CR-GNB detected in the ICUs in our study area may be attributed to the overuse of antibiot- ics, including carbapenems, and improper application of infection control measures. These findings confirm the need for the application of a strict antibiotic stewardship program.

Acinetobacter baumannii has recently been known as a major cause of hospital-and community-acquired infections. Carbapenem resistant A. baumanni (CRAB) has been recorded to be resistant to nearly all antibiotics, including the last resort antibiotics; carbapenems. This study aimed to detect the carbapenem resistance levels and mechanisms, in addition to the genotyping of A. baumanni in Upper Egypt. About 200 clinical samples were collected from different wards of Sohag University Hospital, Egypt, from which 20 A. baumannii isolates were recovered and then identified using conventional methods and Polymerase Chain Reaction (PCR). Antibiotic sensitivity testing was carried out using the Disk diffusion method, followed by PCR testing of the common carbapenemase-encoding genes, including OXA-51, OXA-58, KPC, GES, IMP, NDM, VIM, SIM, and GIM. Genotyping was performed using the Enterobacterial Repetitive Intergenic Consensus-Polymerase chain reaction (ERIC-PCR). About 85 % of A. baumannii strains were multidrug resistant (MDR), and high rate of Extreme drug resistant (XDR) A. baumannii (70 %) was detected. Carbapenem resistance was detected in 65 % of A. baumannii isolates, 70.58 % of MDR isolates, and 85.7 % of XDR isolates, respectively. Carbapenemase-encoding genes, including bla OXA-51 , VIM, NDM, and GES, were detected in 100 %, 100 %, 76.9 2 % and 76.92 % of the carbapenem resistant A. baumannii (CRAB) isolates, respectively. The bla IMP and bla KPC genes had lower prevalence rates of 15.38 % and 30.77 %; respectively, whereas the SIM, GIM, and OXA-58 genes were not detected in any of the tested A. baumanni isolates. All of the MDR isolates carried three or more the carbapenemases encoding genes, and 85.7 % of the XDR isolates carried four or more of the carbapenemase-encoding genes. The dendrogram

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