Abstract
This study analyzed the genotype, antibiotic resistance, and biofilm formation of Acinetobacter baumannii strains and assessed the correlation between biofilm formation, antibiotic resistance, and biofilm-related risk factors. A total of 207 non-replicate multi-drug-resistant A. baumannii strains were prospectively isolated. Phenotypic identification and antimicrobial susceptibility testing were carried out. Isolate biofilm formation ability was evaluated using the tissue culture plate (TCP), Congo red agar, and tube methods. Clonal relatedness between the strains was assessed by enterobacterial repetitive intergenic consensus-PCR genotyping. Of the 207 isolates, 52.5% originated from an intensive care unit setting, and pan resistance was observed against ceftazidime and cefepime, with elevated resistance (99–94%) to piperacillin/tazobactam, imipenem, levofloxacin, and ciprofloxacin. alongside high susceptibility to tigecycline (97.8%). The Tissue culture plate, Tube method, and Congo red agar methods revealed that 53.6%, 20.8%, and 2.7% of the strains were strong biofilm producers, respectively, while a significant correlation was observed between biofilm formation and device-originating respiratory isolates (p = 0.0009) and between biofilm formation in colonized vs. true infection isolates (p = 0.0001). No correlation was detected between antibiotic resistance and biofilm formation capacity, and the majority of isolates were clonally unrelated. These findings highlight the urgent need for implementing strict infection control measures in clinical settings.
Highlights
Acinetobacter baumannii is an opportunistic nosocomial pathogen, frequently causing various infections in humans, including sepsis, meningitis, peritonitis, urinary tract, soft-tissue, and device-related infections, such as ventilator-associated pneumonia [1].Antimicrobial resistance represents a great challenge in A. baumannii isolates and is reported worldwide with notable resistance to major classes and the most frequently utilized antimicrobial agents, including β-lactams, aminoglycosides, and fluoroquinolones [2,3]
MDR A. baumannii isolates were largely clustered in patients aged 45–74 years (n = 94, 45.4%), with children aged
Concurrent with previous reports, we found that the performance of the tissue culture plate (TCP) method was superior to that of Tube method (TM) and Congo red agar (CRA) methods for qualitative analysis of biofilm formation [20,21]
Summary
Antimicrobial resistance represents a great challenge in A. baumannii isolates and is reported worldwide with notable resistance to major classes and the most frequently utilized antimicrobial agents, including β-lactams, aminoglycosides, and fluoroquinolones [2,3]. A. baumannii resistance to carbapenems are on the rise, which limits the treatment options to drugs known for their neurotoxicity and nephrotoxicity, such as Colistin [4]. Most of these strains contain carbapenem-hydrolyzing β-lactamase genes (CHDLs), such as class. Along with its elevated multidrug resistance, the ability of A. baumannii to produce microbial biofilms has caused serious global problems by contributing toward its survival and transmission in hospital environments on biotic and abiotic surfaces, including cerebrospinal fluid shunts and catheters [5]
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