Background:. Atrophic rhinitis is a chronic inflammatory condition of the nasal mucosa which remains as persistent illness and of difficult management. Objectives: -are to evaluate the relation between microbiological flora present in the nose and pathogenesis of primary atrophic rhinitis disease and to detect the antibiotic susceptibility of these microorganisms and detection of the prevalence of Ampc beta lactamase gene among isolated strains. Methodology: This study was done on samples collected from 60 patients attending the Outpatient Clinic of Otorhinolaryngology at Benha University Hospital, collected during the period from February 2019 to September 2019. Bacterial cultures from nasal crust, or discharge were done for isolation of the pathogenic bacteria and detection of their antibiotic susceptibility by Vitek-2 system,multiplex PCR was done to detect AmpC gene in isolated strains. Results: Klebsiella ozeana was isolated in 24 (40%) of the patients followed by Pseudomonas aeruginosa in 12 cases (20%). Klebsiella species showed 5%, 45%, and 65% susceptibility to first, second, and third generation cephalosporins, respectively. It also showed 64% susceptibility to quinolones and 42% susceptibility to amoxycillin plus clavulanic acid. The susceptibilities of the isolated Pseudomonas aeruginosa strains to antibacterial agents were 12%, 59%, and 70% to first, second, and third generation cephalosporins, respectively, and 64% susceptibility to quinolone. From the 45 enterobactericae isolates, 21 (46.7%) were AmpC β-lactamase isolates [13/24 (54.2 %) K.ozeanea, 5/12 (41.7%), 2/6(33.3%) E. coli, 1/3(33.3%) P. mirabilis Conclusion: The bacterial infection of nasal mucosa is the main trigger in patients complaining of primary atrophic rhinitis .