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Advisor(s)
Abstract(s)
Hospital-acquired infections (HAIs) are a rising problem worldwide, and the best way
of coping with them is through infection tracking and surveillance systems, combined with prevention strategies, namely efficient disinfection protocols, that employ various biocides. However,
increasing reports about reductions in biocide susceptibility and the development of cross-resistance
to antimicrobials emphasize the need for identifying the factors influencing biocide efficiency. In
this study, 29 bacterial isolates (n = 3 E. coli, n = 2 Pseudomonas spp., n = 23 Enterococcus spp., and
n = 1 Staphylococcus pseudintermedius), obtained from environmental samples collected from the
Biological Isolation and Containment Unit (BICU), of the Veterinary Teaching Hospital of the Faculty
of Veterinary Medicine, University of Lisbon, were tested in order to determine their antimicrobial
susceptibility to various antibiotics. Thirteen of these isolates were further selected in order to
determine their antimicrobial susceptibility to Virkon™ S, with and without the presence of organic
matter. Afterward, seven of these isolates were incubated in the presence of sub-lethal concentrations
of this formulation and, subsequently, new susceptibility profiles were determined. Fourteen of the
29 isolates (48.3%) were classified as multidrug resistant, all previously identified as enterococci.
Concerning Virkon™ S’s susceptibility, the Minimal Bactericidal Concentration (MBC) of this biocide
regarding all isolates was at least eight times lower than the concentration regularly used, when
no organic matter was present. However, when organic matter was added, MBC values rose up
to 23 times. After exposure to sub-lethal concentrations of Virkon™ S, four enterococci presented
a phenotypical change regarding antimicrobial susceptibility towards gentamicin. Virkon™ S also
resulted in higher MBC values, up to 1.5 times, in the presence of low concentrations of organic
matter, but no rise in these values was observed in assays without interfering substance. Virkon™
S seemed to be an efficient formulation in eliminating all bacteria isolates isolated from the BICU.
However, organic matter could represent a hindrance to this ability, which emphasizes the importance
of sanitization before disinfection procedures. The changes seen in antimicrobial susceptibility could
be explained by a general stress-induced response promoted by the sub-lethal levels of Virkon™ S.
Additionally, when no organic matter was present, a decrease in susceptibility to this biocide seemed
to be non-existent.
Description
Research Areas: Infectious Diseases ; Pharmacology & Pharmacy
Keywords
Biocide Virkon™ S Susceptibility Biological Isolation and Containment Unit antibiotic
Pedagogical Context
Citation
Geraldes C, Verdial C, Cunha E, Almeida V, Tavares L, Oliveira M, Gil S. 2021. Evaluation of a biocide used in the Biological Isolation and Containment Unit of a Veterinary Teaching Hospital. Antibiotics, 10(6):639. DOI:10.3390/antibiotics10060639
Publisher
MDPI