Sarah Khafaja ^1,2 Yara Salameh ¹ Celina Boutros ¹ Cherine Awad ² Kawthar Faour ¹ Nadim Tfaily ¹ Sarah Merhi ¹ Zeinab El Zein ^1,2 Samer Bou Karroum ¹ Dana Oweini ¹ Danielle Fayad ¹ George F Araj ³ Ramia Zakhour ^1,2 Ghassan S Dbaibo ^1,2*

• ¹ Center for Infectious Diseases Research, American University of Beirut Medical Center, Beirut, Beyrouth, Lebanon
• ² Department of Pediatrics and Adolescent Medicine, American University of Beirut Medical Center, Riad El-Solh, Beirut, Lebanon
• ³ Department of Pathology and Laboratory Medicine, Faculty of Medicine, American University of Beirut, Beirut, Beirut, Lebanon

Multidrug resistant Gram-negative bacterial infections are considered a major public health threat.Immunocompromised pediatric patients are at a great risk of severe or overwhelming infections.The aim of this study was to describe the frequency of infections with multidrug resistant (MDR) Gram-negative bacteria (GNB) in immunocompromised pediatric patients and to determine the risk factors. In addition, we aimed to identify the antimicrobial resistance patterns of these isolates.This was a retrospective observational study conducted at the American University of Beirut Medical Center (AUBMC) from 2009 to 2017. The study included immunocompromised patients 18 years of age or younger with infections caused by Gram-negative bacteria isolated from a sterile site, or nonsterile site in the setting of clinical infection.A total of 381 episodes of infection with GNB in 242 immunocompromised pediatric patients were identified. The mean age was 7.7 years. The most common pathogens were Enterobacterales followed by Pseudomonas and Acinetobacter spp. MDR GNB infections predominated causing 72% of the episodes, with alarming MDR rates among Escherichia coli (95.7%) and Klebsiella pneumoniae (82.7%). The overall rate of MDR GNB isolated increased from 62.7% in 2015 to 90% in 2017. Thrombocytopenia, chemotherapy and previous colonization or infection with the same organism during the past 12 months were found to be independent risk factors for infection with MDR GNB.This study provides data on the epidemiology of infections with MDR GNB in immunocompromised pediatric patients and illustrates the alarmingly high prevalence of these infections. This necessitates the frequent revisiting of treatment guidelines in these high-risk patients and the implementation of judicious antimicrobial stewardship programs and infection control policies to stabilize or decrease the prevalence of these infections.The x-axis represents the years from 2009 to 2017 (to note that the included cultures were from June 1 st to December 31 st for the year 2009 and from January 1 st to June 31 st for 2017), and the yaxis is the number of organisms per year. The line graph represents the percentage of MDR GNB.