Title : Profile of beta-lactamases in multidrug-resistant (MDR) acinetobacter baumannii strains in lithuania 2016-2017 and 2021-2022 years
Introduction: Acinetobacter baumannii (A. baumannii) is an important nosocomial pathogen that possesses not only intrinsic resistance to many classes of antibiotics, but also has a propensity for rapid development of antimicrobial resistance during treatment.
Aims & Objectives: Aim of our study was to investigate A. baumannii strains producing different beta-lactamases. A total of 223 A. baumannii were isolated from different clinical samples of patients treated in 2016-2017 and 2021-2022 years in Hospital of Lithuanian University of Health Sciences.
Methods: ESBL plus AmpC screen disc kit (Abtek Biologicals, UK) was used to determine the production of the extended spectrum β-lactamase (ESBL) and AmpC β-lactamase. Combination meropenem disc test was used to determine the co-production of KPC and MBL carbapenemases. For the statistical analysis were used Chi-square test and multivariate analysis; p <0.05 was considered statistically significant.
Results: All isolates had a multidrug resistant profile, and all were resistant to the carbapenems but remained susceptible to colistin. Phenotypic method showed that 60.9% (n=142) of A. baumannii strains were AmpC β lactamase, 11.6% (n=27) ESBL and 76.8% (n=179) KPC β lactamase producers. 46.3% (n=108) of A. baumannii strains had AmpC plus KPC β lactamases, 2.6 % (n=6) AmpC plus ESBL, 2.6 % (n=6) ESBL plus KPC and 3.8% (n=9) AmpC plus KPC plus ESBL.
All tested strains were divided into fourth groups: non producing β - lactamase (9.9%, n=23), producing only AmpC, KPC or ESBL (34.8%, n=81), producing two diferent β - lactamases: AmpC plus KPC, AmpC plus ESBL or ESBL plus KPC (51.5%, n=120) and the last group: producing all β - lactamases (3.9%, n=9). We have found that all A.baumannii strains were β - lactamase producers in 2021/2022 while 17.7% (n=23) strains didn’t produce any β - lactamase in 2016/2017. In 2016-2017 only one β - lactamase producing stains were detected in 62.3% of tested strains while in 2021-2022 no one only one β - lactamase producing strains were detected. A.baumannii strains producing two different β - lactamases were more frequently identified in 2021/2022 compared to 2016-2017 (94.2% (n=97) compared to (17.7% (n=23), p<0.001). ESBL, AmpC and KPC β - lactamase producing strains were identified 5.8 % (n=6) in 2021-2022 and only 1.3 % (n=3) in 2016-2017 (p<0,001).
Conclusions: Increased synthesis of β - lactamases in 2021-2022 compared to 2016-2017 years is a serious warning because β - lactamases are a major threat to the effectiveness of antibiotics that are currently available for medical uses.
Audience Take Away:
- Phenotypic methods for the detection of β - lactamases are easy and simple and can be implemented in routine diagnostic laboratories along with susceptibility testing. These data will assist the clinicians in the management and control of infections.