Periodic phenotypic profile analysis of Acinetobacter baumannii drug resistance characteristics showing the emergence of PDR.

Abstract

Objective: Acinetobacter baumannii, one of the ESKAPE pathogens, is on the World Health Organization (WHO) list of priorities needing urgent new effective antimicrobial agents due to exhibited high resistance by the bacterium to currently available antibiotics. This study examines the periodic changes of clinical A. baumannii isolates and their antimicrobial resistance patterns and types in Southeastern region of Saudi Arabia.

Materials and methods: One hundred and seventy-seven randomly selected A. baumannii isolates were used for the investigation with bacterial identities (IDs) and antimicrobial assay ascertained with Gram-negative (GN) ID cards and antimicrobial susceptibility test (AST) cards of Vitek 2 Compact Automated System according to manufacturer's guidelines. Descriptive phenotypic types of isolates were compared using comparison proportion and Fisher extraction test, while Morpheus versatile matrix visualization and analysis software was used for the dendrogram of hierarchical clustering.

Results: A significantly higher proportion of samples were from males compared to females (p = 0.025), with 33.33% of samples originating from patients aged 51-70 years. Resistance was high for imipenem (93%), meropenem (94%), levofloxacin, ciprofloxacin (99%), and aztreonam (98%). There was less percentage resistance to colistin (18%), tigecycline (23%), and minocycline (23%). Multidrug resistance (MDR)/carbapenem-resistant Acinetobacter baumannii (CRAB) was observed consistently across all years. There was no extensive drug resistance (XDR) among isolates from 2013 to 2014, but it was present in the 2016 to 2018 and 2019 to 2020 periods, while pandrug resistance was seen only in the 2019 to 2020 isolates.

Conclusions: The study shows a clear trend of the isolates changing from MDR to XDR and then to pandrug resistance over the study period. Also, it indicates that carbapenems might no longer be a treatment choice in this study region. Although colistin exhibited less resistance, the toxicity of the drug reduces its usefulness. The development of pandrug resistance is a critical concern.