Serry Fathy M E, Kadry Ashraf A, Abdelrahman Abdou A
Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt.
J Ind Microbiol Biotechnol. 2003 Mar;30(3):135-40. doi: 10.1007/s10295-002-0007-z. Epub 2003 Mar 20.
The present study aimed to isolate, select, and evaluate bacterial isolates with potential for use as biological indicators for sterilization with glutaraldehyde and/or formaldehyde. A total of 340 local Bacillus isolates were screened for glutaraldehyde and/or formaldehyde resistance by determination of minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), and extinction time and were compared with B. subtilis (var. niger) ATCC 9372, the biological indicator for ethylene oxide sterilization, as reference. Of these, 85 isolates had glutaraldehyde MICs of 0.5% or higher, while 29 had formaldehyde MICs of 0.04% or higher. Of the 29 resistant isolates, 15 had MBCs of 0.05% or more. Extinction times were used to evaluate the bactericidal/sporicidal activity of glutaraldehyde. Eight had inactivation times of more than 5 h in 2% glutaraldehyde (pH 8), whereas 12 had inactivation times of more than 3 h in l% formaldehyde, with one isolate in common. These 19 isolates were selected and evaluated as potential biological indicators for aldehydes by determination of the decimal reduction times ( D values), compared with the reference strain. Eight glutaraldehyde-resistant isolates exhibited D values 2.0- to 3.5-fold higher than the reference strain (30 min.). Only five of 12 formaldehyde resistant isolates had D values higher than that of the reference strain. Using six resistant isolates, temperature coefficient values between 2.11 and 3.02 were obtained for 2% formaldehyde. Finally, 14 isolates were tested for potential pathogenicity and were identified to species level. All of the eight glutaraldehyde-resistant isolates, including the isolate with dual resistance, and three formaldehyde-resistant isolates were B. licheniformis, while two other formaldehyde-resistant isolates were B. cereus. Six of the selected B. licheniformis isolates are potential biological indicators for sterilization processes using aldehydes. Three can be suggested for glutaraldehyde only and three for both aldehydes.
本研究旨在分离、筛选和评估有潜力用作戊二醛和/或甲醛灭菌生物指示剂的细菌分离株。通过测定最低抑菌浓度（MICs）、最低杀菌浓度（MBCs）和灭活时间，对总共340株本地芽孢杆菌分离株进行了戊二醛和/或甲醛抗性筛选，并与环氧乙烷灭菌的生物指示剂枯草芽孢杆菌（黑色变种）ATCC 9372作为对照进行比较。其中，85株分离株的戊二醛MICs为0.5%或更高，而29株的甲醛MICs为0.04%或更高。在这29株抗性分离株中，15株的MBCs为0.05%或更高。采用灭活时间来评估戊二醛的杀菌/杀孢子活性。8株在2%戊二醛（pH 8）中的灭活时间超过5小时，而12株在1%甲醛中的灭活时间超过3小时，有1株分离株在两者中均有。通过测定对数下降时间（D值），将这19株分离株作为醛类潜在生物指示剂进行筛选和评估，并与对照菌株进行比较。8株戊二醛抗性分离株的D值比对照菌株（30分钟）高2.0至3.5倍。12株甲醛抗性分离株中只有5株的D值高于对照菌株。使用6株抗性分离株，得到2%甲醛的温度系数值在2.11至3.02之间。最后，对14株分离株进行了潜在致病性测试并鉴定到种水平。所有8株戊二醛抗性分离株，包括具有双重抗性的分离株，以及3株甲醛抗性分离株均为地衣芽孢杆菌，另外2株甲醛抗性分离株为蜡样芽孢杆菌。所选的6株地衣芽孢杆菌分离株是醛类灭菌过程的潜在生物指示剂。其中3株仅适用于戊二醛，3株适用于两种醛类。
