Background: Secondary bacterial pneumonia especially with multidrug resistant (MDR) organisms is one of the devastating complications that can worsen COVID-19 patients' outcomes. The study aimed to evaluate the impact of secondary MDR bacterial pneumonia on COVID-19 patients' outcomes with molecular detection of genes involved in antimicrobial resistance among isolates of the most prevalent causative pathogen. Methods: The study included 50 critically ill patients with acute severe COVID-19 with evidence of secondary MDR bacterial pneumonia, 50 critically ill patients with acute severe COVID-19 without evidence of secondary bacterial pneumonia, and 30 clinically stable patients with acute moderate COVID-19 infections. Respiratory samples were cultured for identification and antibiotic susceptibility of the causative pathogens. MDR/XDR A. baumannii, the most prevalent pathogen, was screened for multiple antibiotic resistance genes using single-plex and multiplex polymerase chain reactions. Results: Critically ill COVID-19 patients with secondary MDR bacterial pneumonia in group I had a significantly higher mortality rate. MDR/XDR A. baumannii was the most prevalent pathogen (39.2%) isolated with the highest cause specific mortality rate (38%). Multiple resistance genes were detected including 𝑏𝑙𝑎OXA-51, 𝑏𝑙𝑎OXA-48, 𝑏𝑙𝑎OXA-24, 𝑏𝑙𝑎ADC, 𝑏𝑙𝑎CIT, 𝑏𝑙𝑎KPC, aacA4, aacC1, acc (6'), aphA1, aph6, and aadA1. Conclusion: Secondary MDR bacterial pneumonia had a significant impact on critically ill COVID-19 patients with a significantly higher mortality rate. Thus, preventing secondary MDR bacterial pneumonia through infection prevention measures, including standard precautions, preventive care bundles and antimicrobial stewardship programs, should be strictly implemented to protect critically ill COVID-19 patients and help avoid its detrimental effect on patients' outcomes.

Background: Multidrug resistant infection is the leading cause of ICU morbidity and mortality. Gram-negative bacilli are the most prevalent pathogens with Acinetobacter being the most resistant. Objectives: Phenotypic and genotypic characterization of multidrug-and extensively drug-resistant Acinetobacter and Enterobacteriaceae species causing infections in critically ill patients with detection of targeted β-lactamase genes and its impact on patients' morbidity and mortality. Methodology: Antibiotic susceptibility testing was done. Genes for class A and class B β-lactamases were detected by multiplex polymerase chain reaction (PCR) and 5 carbapenemases genes were detected by real time PCR using GeneXpert Carba-R system. Results: 16.6 % of A. baumannii were MDR, 50% were XDR, 50% of K. pneumoniae were XDR and 100% of P. stuartii were XDR. Detected genes included bla SHV , bla CTX-M , bla GIM-1 , bla SIM-1 , bla OXA-48 and bla NDM-1 . Conclusion: MDR/XDR infections had a significant impact on patients' mortality. Molecular epidemiology is crucial to guide infection control committees about preventive measures that can contain MDR/XDR infections and prevent their detrimental effect on patients' outcome.