New methods in the evaluation of chemical disinfectants used in health care services.
BACKGROUND
A considerable number of tests are recommended in the literature to evaluate in vitro commercial chemical solutions. The variety of tests reflects their limitations and the need to enhance disinfection process.


METHODS
In this study the efficacy of 4 chemical disinfectants selected by their practical use in Health Care Services and by literature recommendation in aerobic and in strict anaerobic bacteria were evaluated by their practical use in Health Care Services and by literature recommendation in aerobic and in strict anaerobic bacteria. Viability was tested in biofilms grown on glass and rubber tip carriers.


RESULTS
The results showed microbial growth in chemical solutions at concentrations recommended by the literature or at very close concentrations to them. Viable cells were recovered from biofilms after 30 minutes (Bacteroides fragilis) and 60 minutes (Streptococcus mutans and Salmonella tiphymurium) contact with 2.4% glutaraldehyde and after 60 minutes (S tiphymurium) in 2.0% glutaraldehyde. In 70% ethyl alcohol, S tiphymurium was viable up to 10 minutes, Escherichia coli up to 30 minutes, and S mutans up to 60 minutes. In 1% sodium hypochlorite, S mutans was viable up to 30 minutes and S tiphymurium up to 45 minutes. Detection of cell viability could be related to methodologic differences, including biofilm formation, as demonstrated by scanning electron microscopy. It should be emphasized that B fragilis, the most clinically relevant obligate anaerobe, remained viable in one routinely used solution.


CONCLUSIONS
These findings pointed out the need of periodic surveillance of disinfectants' activity used in Health Care Services and the need of reviewing routines of disinfection protocols.
Vieira
Cristina Dutra
CD
Federal University of Minas Gerais, Belo Horizonte, Brazil.
Farias
Luiz de Macêdo
Lde M
Diniz
Cláudio Galuppo
CG
Alvarez-Leite
Maria Eugênia
ME
Camargo
Elizabeth Ribeiro da Silva
ER
Carvalho
Maria Auxiliadora Roque de
MA
D001419:Bacteria / Q000187:drug effects / Q000648:ultrastructure; D018441:Biofilms / Q000187:drug effects; D004202:Disinfectants / Q000494:pharmacology*; D000431:Ethanol / Q000494:pharmacology; D005976:Glutaral / Q000494:pharmacology; D006997:Hypochlorous Acid / Q000494:pharmacology; D008826:Microbial Sensitivity Tests / Q000379:methods; D008855:Microscopy, Electron, Scanning; D010463:Peracetic Acid / Q000494:pharmacology
D004202:Disinfectants; D000431:Ethanol; D006997:Hypochlorous Acid; D010463:Peracetic Acid; D005976:Glutaral