Biocide susceptibilities and biofilm-forming capacities of Acinetobacter baumannii clinical isolates from Malaysia

Abstract

Introduction. Acinetobacter baumannii is a Gram-negative nosocomial pathogen that has the capacity to develop resistance to all classes of antimicrobial compounds. However, very little is known regarding its susceptibility to biocides (antiseptics and disinfectants) and capacity to form biofilms, particularly for Malaysian isolates.
 Aim. To determine the susceptibility of A. baumannii isolates to commonly-used biocides, investigate their biofilm-forming capacities and the prevalence of biocide resistance and biofilm-associated genes.
 Methodology. The minimum inhibitory concentration (MIC) values of 100 A. baumannii hospital isolates from Terengganu, Malaysia, towards the biocides benzalkonium chloride (BZK), benzethonium chloride (BZT) and chlorhexidine digluconate (CLX), were determined by broth microdilution. The isolates were also examined for their ability to form biofilms in 96-well microplates. The prevalence of biocide resistance genes qacA, qacE and qacDE1 and the biofilm-associated genes bap and abaI were determined by polymerase chain reaction (PCR).
 Results. Majority of the A. baumannii isolates (43%) showed higher MIC values (> 50 µg/mL) for CLX than for BZK (5% for MIC > 50 µg/mL) and BZT (9% for MIC > 50 µg/mL). The qacDE1 gene was predominant (63%) followed by qacE (28%) whereas no isolate was found harbouring qacA. All isolates were positive for the bap and abaI genes although the biofilm-forming capacity varied among the isolates.
 Conclusion. The Terengganu A. baumannii isolates showed higher prevalence of qacDE1 compared to qacE although no correlation was found with the biocides’ MIC values. No correlation was also observed between the isolates’ biofilm-forming capacity and the MIC values for the biocides.

Polymyxin Resistance Among XDR ST1 Carbapenem-Resistant Acinetobacter baumannii Clone Expanding in a Teaching Hospital

“…Skin decolonization with chlorhexidine bathing may help prevent catheter colonization and catheter-related bloodstream infections (Fan et al, 2019). Chlorhexidine MICs of all of our isolates are in a range already described in the literature for A. baumannii (Biswas et al, 2019;Nor A'shimi et al, 2019) with no difference among polymyxin-resistant and polymyxin-susceptible strains. The MICs (16-32 mg/L) were lower than the patient bathing solutions concentration (2% chlorhexidine gluconate, or 20,000 mg/L), suggesting that the bathing would benefit the spread control if those strains colonized the patients' skin.…”

Antibiogram and biofilm-forming capacity of Acinetobacter baumannii isolated from Anbar hospitals

“…The capacity of A. baumannii to produce biofilms in a four-step process, namely, attachment of bacteria to the surface, creation of micro-colonies, maturation of biofilms, and ultimately dissociation leading to additional colonization, is a significant virulence factor. The capacity to generate biofilm is one of the most critical aspects in A. baumannii pathogenicity among many virulence factors [29].…”

Mechanism Underlying the Role of LuxR Family Transcriptional Regulator abaR in Biofilm Formation by Acinetobacter baumannii

“…Multidrug resistance may complicate the treatment of serious infections. Biofilm-forming ability has been found to be the major factor affecting drug resistance by A. baumannii [ 29 , pp. 626–633].…”