Effects of biocide exposure on P. Aeruginosa, E. coli and A. Baumannii complex isolates from hospital and household environments

Abstract

Background: Bacterial responses to biocide exposure and its effects on survival and persistence remain to be studied in greater detail. Aim: To analyse the viability and survival of environmental isolates from household and hospital settings after biocide exposure. Methods: The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of chlorhexidine (CHxG), benzalkonium chloride (BAC) and triclosan (TC) were determined in isolates of Pseudomonas aeruginosa, Acinetobacter baumannii complex and Escherichia coli collected from hospital and households environments. Viability was monitored after exposure and removal of biocides using agar cultures and flow cytometry. Findings: P. aeruginosa isolates showed greater tolerance for all biocides tested whereas A. baumannii complex and E. coli were less tolerant. When compared with reference strains, biocide tolerance was up to 8 to 13-fold higher for TC and BAC respectively. Flow cytometry showed that biocide exposure may induce viable but non-growing states in P. aeruginosa and E. coli isolates before becoming fully replicative. Changes in the susceptibility profile in one isolate of A. baumannii complex were observed after biocide exposure. Discussion: Bacteria isolates from hospital and households were able to recover after biocide exposure at bactericidal concentrations favouring persistence and spread of biocide-tolerant strains. This study reinforces that cleaning compliance should be monitored by non-culture based tests. Novel formulations in cleaning and disinfection protocols should be revisited in hospitals harbouring P. aeruginosa and A. baumannii multidrug resistant isolates.

Prevalence of resistance genes to biocides in antibiotic-resistant Pseudomonas aeruginosa clinical isolates

“…Therefore, it seems that hygiene control of surfaces and medical equipments in the hospital settings in terms of P. aeruginosa contamination is important because nosocomial infections are considered as a growing global threat in terms of economical and public health [3]. The most common antiseptic and disinfectant biocides used in clinical settings are chlorhexidine digluconate (a biguanide, disrupting the cell membrane), benzalkonium chloride (a quaternary ammonium compound, disrupting the cell membrane), triclosan (a bisphenol, blocking of lipid biosynthesis) and formaldehyde (an aldehyde, alkylating agent) [4,5]. However, several studies have reported bacterial resistance to various biocides due to the presence of resistance genes [6].…”

“…However, several studies have reported bacterial resistance to various biocides due to the presence of resistance genes [6]. On the other hand, the risk of P. aeruginosa infections in ICU-hospitalized patients is high (up to 30%) despite applying hygiene programs [5]. Such a high prevalence can be attributed to the reduced susceptibility of P. aeruginosa strains against a variety of antiseptics and disinfectants over time [7].…”

Prevalence of Resistance Genes to Biocides in Antibiotic-Resistant Pseudomonas Aeruginosa Clinical Isolates

“…Therefore, it seems that hygiene control of surfaces and medical equipments in the hospital settings in terms of P. aeruginosa contamination is important because nosocomial infections are considered as a growing global threat in terms of economical and public health [3]. The most common antiseptic and disinfectant biocides used in clinical settings are chlorhexidine digluconate (a biguanide), benzalkonium chloride (a quaternary ammonium compound), triclosan (a bisphenol) and formaldehyde (an aldehyde) [4,5]. However, several studies have reported bacterial resistance to various biocides due to the presence of resistance genes.…”

“…However, several studies have reported bacterial resistance to various biocides due to the presence of resistance genes. On the other hand, the risk of P. aeruginosa infections in ICU-hospitalized patients is high (up to 30%) despite applying hygiene programs [5]. Such a high prevalence can be attributed to the resistance of P. aeruginosa strains against a variety of antiseptics and disinfectants over time [6].…”

“…Another problem is the emergence of multi-drug resistant (MDR) P. aeruginosa strains, which can lead to treatment failure [3]. Interestingly, P. aeruginosa strains have shown cross-resistance to biocides and antibiotics with probably similar mechanisms, thereby making bacterial elimination from hospital environments di cult [5,7]. Therefore, obtaining information on the prevalence and mechanisms of bacterial resistance to antimicrobial agents and the selection of suitable biocides and antibiotics can be helpful for controlling hospital-acquired infections caused by P. aeruginosa.…”