Nemec Alexandr, Maixnerová Martina, van der Reijden Tanny J K, van den Broek Peterhans J, Dijkshoorn Lenie
Centre of Epidemiology and Microbiology, National Institute of Public Health, Prague, Czech Republic.
J Antimicrob Chemother. 2007 Sep;60(3):483-9. doi: 10.1093/jac/dkm231. Epub 2007 Jun 26.
To assess the occurrence of the genes of the AdeABC efflux system and their association with antimicrobial resistance in Acinetobacter baumannii.
A set of 116 strains selected for their diversity both in genotypic properties and geographic origin was investigated for the presence of the structural (adeA, adeB and adeC) and regulatory (adeR and adeS) genes of the AdeABC system by PCR, for resistance to 11 antimicrobials by disc diffusion, for MIC of netilmicin and for the presence of aacC2 and aacA4, encoding netilmicin-modifying enzymes.
Ninety-five strains were positive for adeA, adeB, adeR and adeS, 10 were positive for 1 to 3 of these genes and 11 were negative for all genes. The adeC gene was found in 49 strains with one or more of the other genes. Forty-one strains were resistant to a maximum of one agent and 75 strains to two or more agents. Netilmicin MICs showed an almost bimodal distribution with respective peaks of 0.5-1 and 8 mg/L; aacC2 or aacA4 was found in six strains with netilmicin MIC of >or=64 mg/L. All 61 strains with netilmicin MICs >or= 4 mg/L were both adeABRS-positive and resistant to two or more agents, whereas netilmicin MICs <or= 2 mg/L (n = 51) were found for all strains resistant to a maximum of one agent and those negative for one or more of the adeABRS genes.
The AdeABC genes are common in A. baumannii, but may be absent in some, mostly fully susceptible strains. Decreased susceptibility to netilmicin (MIC 4-32 mg/L) is associated with both the presence of these genes and multidrug resistance and may be indicative of AdeABC overexpression.
评估鲍曼不动杆菌中AdeABC外排系统基因的存在情况及其与抗菌药物耐药性的关联。
通过聚合酶链反应（PCR）研究一组116株因其基因型特性和地理来源的多样性而被挑选出的菌株，检测AdeABC系统的结构基因（adeA、adeB和adeC）和调控基因（adeR和adeS）的存在情况；采用纸片扩散法检测对11种抗菌药物的耐药性；检测奈替米星的最低抑菌浓度（MIC）；检测编码奈替米星修饰酶的aacC2和aacA4基因的存在情况。
95株菌株的adeA、adeB、adeR和adeS基因呈阳性，10株这些基因中有1至3个呈阳性，11株所有基因均为阴性。在49株带有一个或多个其他基因的菌株中发现了adeC基因。41株菌株对最多一种药物耐药，75株对两种或更多种药物耐药。奈替米星的MIC呈现几乎双峰分布，峰值分别为0.5 - 1 mg/L和8 mg/L；在6株奈替米星MIC≥64 mg/L的菌株中发现了aacC2或aacA4基因。所有61株奈替米星MIC≥4 mg/L的菌株adeABRS均为阳性且对两种或更多种药物耐药，而奈替米星MIC≤2 mg/L（n = 51）的情况见于所有对最多一种药物耐药的菌株以及adeABRS基因中有一个或多个为阴性的菌株。
AdeABC基因在鲍曼不动杆菌中很常见，但在一些大多对药物敏感的菌株中可能不存在。对奈替米星敏感性降低（MIC为4 - 32 mg/L）与这些基因的存在以及多重耐药性均有关联，可能表明AdeABC过表达。
