by William A. Rutala, PhD, MPH, David J. Weber MD, MPH
Carbapenem-resistant Enterobacteriaceae (CRE) have broad resistance to most β-lactam antibiotics and are a growing worldwide problem. CRE infections are difficult to treat, have a substantial mortality, and are involved in healthcare-associated outbreaks via contaminated environmental surfaces and medical equipment. Colistin-resistant Enterobacteriaceae carrying the mcr-1 gene are a global health concern since colistin is often a last-line antibiotic used to treat CRE. Furthermore, a recent study from China described a hospital outbreak caused by MCR-1-producing Klebsiella pneumoniae with potential spread of mcr-1 via the hospital environment.
Although there is currently no strong scientific evidence demonstrating that clinical use of disinfectants/antiseptics is associated with selection of antibiotic-resistant organisms, some studies have described reduced susceptibility to disinfectants (e.g., quaternary ammonium compounds [QAC]), antiseptics (e.g., chlorhexidine), and cross-resistance (e.g., benzalkonium chloride/quinolones). Susceptibility to germicides (e.g., disinfectants, antiseptics) for carbapenem- or
colistin-resistant Enterobacteriaceae is poorly described. Kanamori et al recently published a paper on the efficacy of multiple germicides against these emerging antibiotic-resistant pathogens using a disc-based quantitative carrier test method.
The efficacy of germicides with active ingredient, product name, and classification against test organisms is summarized in Table 1. Overall, most germicides reached at least 3-log10 reduction (20/22 [91%] for KPC-K. pneumoniae, 22/22 [100%] for KPC-E. cloacae, 18/22 [82%] for KPC-E.coli, 19/22 [86%] for MCR-1-E. coli). Furthermore, all germicides, except for two products (1% chlorhexidine gluconate plus 61% ethyl alcohol and 3% hydrogen peroxide) against MCR-1-E. coli, demonstrated at least 2-log10 reduction for these pathogens even in challenging test conditions (5% FCS and 1 minute exposure time). Given that hospital environmental surfaces generally have <2-log10 organisms/cm2, this level of kill is likely sufficient for use as a surface disinfectant. Thus, these study results demonstrated that germicides commonly used in healthcare facilities likely will be effective against carbapenem/colistin-resistant Enterobacteriaceae when used appropriately. See Table 1 next page.
Kanamori H, Rutala WA, Gergen MF, Sickbert-Bennett EE, Weber DJ. Germicidal activity against carbapenem-resistant Enterobacteriaceae using a quantitative carrier test method. Antimicrob Agents Chemotherapy 2018;60:1-5
Table 1. Efficacy (mean log10 reductions) of the 21 germicides against carbapenem/colistin-resistant Enterobacteriaceae using a quantitative carrier test method.
|Active Ingredient||Formulation Tested||Classification||
|10% povidone-iodine / 1% titratable iodine||Undiluted||Antiseptic||3.4||2.9||3.5||3.9|
|0.5% triclosan||Undiluted||Antiseptic / Handwash||2.3||2.9||3.3||3.8|
|1% chloroxylenol||Undiluted||Antiseptic / Handwash||4.3||3.7||4.5||4.4|
|1% chlorhexidine gluconate solution, 61% ethyl alcohol||Undiluted||Antiseptic / Surgical Hand Scrub||2.6||3.8||3.7||1.8|
|2% chlorhexidine gluconate solution||Undiluted||Antiseptic / Surgical Hand Scrub / Handwash||3.4||3.5||3.4||4.1|
|4% chlorhexidine gluconate solution||Undiluted||Antiseptic / Surgical hand scrub / Handwash||3.1||4.0||3.5||4.4|
|70% isopropyl alcohol||Undiluted||Antiseptics / Disinfectant||4.6||4.0||4.9||4.4|
|5.25% sodium hypochlorite||1:10 dilution||Disinfectant||4.9||5.6||5.9||4.4|
|5.25% sodium hypochlorite||1:50 dilution||Disinfectant||4.9||3.5||3.4||4.4|
|9.09% o-phenylphenol, 7.66% p-tertiary amylphenol||1:128 dilution||Disinfectant||4.9||5.6||5.8||4.4|
|3% hydrogen peroxide||Undiluted||Disinfectant||2.2||3.5||3.2||1.7|
|1.4% hydrogen peroxide||Undiluted||Disinfectant||4.9||5.6||5.8||4.4|
|58% ethanol, 0.1% QACa||Undiluted||Disinfectant||4.9||5.6||5.8||4.4|
|21.7% QACb||1:256 dilution||Disinfectant||4.9||3.5||4.7||4.4|
|55% isopropyl alcohol, 0.5% QACc||Undilutede||Disinfectant||4.9||5.2||5.8||4.4|
|28.7% isopropyl alcohol, 27.3% ethyl alcohol, 0.61% QACd||Undilutede||Disinfectant||4.8||5.6||5.9||4.4|
|35% peracetic acid||0.20%||High-level Disinfectant / Chemical Sterilant||4.9||5.6||5.8||4.4|
|0.55% ortho-phthalaldehyde||Undiluted||High-level Disinfectant / Chemical Sterilant||2.4||4.8||3.4||2.0|
|2.4% glutaraldehyde||Undiluted||High-level Disinfectant / Chemical Sterilant||4.9||5.6||5.8||4.4|
|27.5% hydrogen peroxide, 5.8% peroxyacetic acid||1:43 dilution||High-level Disinfectant / Chemical Sterilant||4.9||5.6||5.8||4.4|
|2% accelerated hydrogen peroxide||Undiluted||High-level Disinfectant / Chemical Sterilant||5.2||5.9||5.8||4.4|
Values are shown in mean log10 reductions under a test condition of 106 test organisms with 5% fetal calf serum and 1 minute contact time.
a, QAC, quaternary ammonium compounds: Alkyl (C14 50%, C12 40%, C16 10%) dimethyl benzyl ammonium saccharinate 0.1%.
b, QAC: Octyl decyl dimethyl ammonium chloride 6.51%; Dioctyl dimethyl ammonium chlorid 2.604%; Didecyl dimethyl ammonium chlorid 3.906%; Alkyl (50% C14, 40% C12, 10%