The efficacy of chemical agents in cleaning and disinfection programs

TLDR

Hospital nurseries face increasing infection outbreaks, making effective sanitation programs with appropriately chosen chemical agents essential. The study determined minimum inhibitory concentrations by successive broth dilutions against reference strains of *Bacillus subtilis*, *Bacillus stearothermophilus*, *Escherichia coli*, *Staphylococcus aureus*, and outbreak isolates of *Enterobacter cloacae*, *Serratia marcescens*, and *Acinetobacter calcoaceticus*. MICs ranged from 59–156 mg/L for quaternary ammonium compounds to 18,500 mg/L for peracetic acid, with chlorhexidine ineffective against germinating spores and *Acinetobacter calcoaceticus* showing broad resistance.

Abstract

Due to the growing number of outbreaks of infection in hospital nurseries, it becomes essential to set up a sanitation program that indicates that the appropriate chemical agent was chosen for application in the most effective way. For the purpose of evaluating the efficacy of a chemical agent, the minimum inhibitory concentration (MIC) was reached by the classic method of successive broth dilutions. The reference bacteria utilized were Bacillus subtilis var. globigii ATCC 9372, Bacillus stearothermophilus ATCC 7953, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923. The strains of Enterobacter cloacae IAL 1976 (Adolfo Lutz Institute), Serratia marcescens IAL 1478 and Acinetobactev calcoaceticus IAL 124 (ATCC 19606), were isolated from material collected from babies involved in outbreaks of infection in hospital nurseries. The MIC intervals, which reduced bacteria populations over 08 log10, were: 59 to 156 mg/L of quaternarium ammonium compounds (QACs); 63 to 10000 mg/L of chlorhexidine digluconate; 1375 to 3250 mg/L of glutaraldehyde; 39 to 246 mg/L of formaldehyde; 43750 to 87500 mg/L of isopropanol or ethanol; 1250 to 6250 mg/L of iodine in polyvinyl-pyrolidone complexes, 150 to 4491 mg/L of chlorine-releasing-agents (CRAs); 469 to 2500 mg/L of hydrogen peroxide; and, 2310 to 18500 mg/L of peracetic acid. Chlorhexidine showed non inhibitory activity over germinating spores. A. calcoaceticus, was observed to show resistance to the majority of the agents tested, followed by E. cloacae and S. marcescens.