First data on antimicrobial susceptibility patterns of Moraxella catarrhalis isolates in Lebanon

Background. Moraxella catarrhalis is an important bacterial pathogen. Although national data have shown an increase in the levels of antimicrobial resistance in clinical settings in Lebanon, there is a lack of data regarding this human pathogen. This study aimed to determine for the first time the antimicrobial susceptibility profiles of M. catarrhalis isolates in Lebanon. Methods. A total of 34 M. catarrhalis strains were isolated from clinical specimens during the period from November 2010 to March 2019. Bacterial identification was carried out using matrix assisted laser desorption ionization–time of flight mass spectrometry. Antibiotic susceptibility of all isolates was performed according the recommendations of the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Results. A total of 34 non-duplicated M. catarrhalis strains were isolated from nose (n=19), ear (n=7), sputum (n=5), blood (n=1), eye (n=1), and throat (n=1) of patients referred to Nini Hospital in Tripoli, North governorate of Lebanon. Regarding antibiotic susceptibility rates, the percent susceptibility is 100% to the majority of antibiotics, except ampicillin (7.4%), trimethoprim-sulfamethoxazole (85.3%), nalidixic acid (85.3%), and ciprofloxacin (97.1%). Conclusion. To our knowledge, this study is the first investigation regarding the antimicrobial susceptibility patterns of M. catarrhalis isolates in Lebanon. In addition to the high level of resistance to ampicillin, our findings showed the emergence of resistance to trimethoprim-sulfamethoxazole, nalidixic acid and ciprofloxacin. Even if this study provides useful information to develop effective empirical treatment, we recommend the implementation of reliable diagnostic tools to guide appropriate treatment.