Fontana Carla, Favaro Marco, Campogiani Laura, Malagnino Vincenzo, Minelli Silvia, Bossa Maria Cristina, Altieri Anna, Andreoni Massimo, Sarmati Loredana
Department of Experimental Medicine, "Tor Vergata" University, 00133 Rome, Italy.
Laboratory of Microbiology, Polyclinic of "Tor Vergata", 00133 Rome, Italy.
Microorganisms. 2021 Nov 15;9(11):2356. doi: 10.3390/microorganisms9112356.
Several carpabenemase (KPC) gene mutations are associated with ceftazidime/avibactam (CAZ-AVI) resistance. Here, we describe four subsp. CAZ-AVI-resistant clinical isolates, collected at the University Hospital of Tor Vergata, Rome, Italy, from July 2019 to February 2020. These resistant strains were characterized as KPC-3, having the transition from cytosine to thymine (CAC-TAC) at nucleotide position 814, with histidine that replaces tyrosine (H272Y). In addition, two different types of KPC gene mutations were detected. The first one, common to three strains, was the D179Y (G532T), associated with CAZ-AVI resistance. The second mutation, found only in one strain, is a new mutation of the KPC-3 gene: a transversion from thymine to adenine (CTG-CAG) at nucleotide position 553. This mutation causes a KPC variant in which glutamine replaces leucine (Q168L). None of the isolates were detected by a rapid immunochromatographic assay for detection of carbapenemase (NG Biotech, Guipry, France) and were unable to grow on a selective chromogenic medium Carba SMART (bioMerieux, Firenze, Italy). Thus, they escaped common tests used for the prompt detection of KPC-producing.
几种碳青霉烯酶（KPC）基因突变与头孢他啶/阿维巴坦（CAZ-AVI）耐药性相关。在此，我们描述了2019年7月至2020年2月在意大利罗马的托尔韦尔加塔大学医院收集的4株耐CAZ-AVI临床分离株。这些耐药菌株被鉴定为KPC-3型，在核苷酸位置814处发生了从胞嘧啶到胸腺嘧啶的转变（CAC-TAC），导致组氨酸取代酪氨酸（H272Y）。此外，还检测到两种不同类型的KPC基因突变。第一种是三株菌株共有的D179Y（G532T），与CAZ-AVI耐药性相关。第二种突变仅在一株菌株中发现，是KPC-3基因的一种新突变：在核苷酸位置553处发生了从胸腺嘧啶到腺嘌呤的颠换（CTG-CAG）。这种突变导致了一种KPC变体，其中谷氨酰胺取代了亮氨酸（Q168L）。通过快速免疫层析法检测碳青霉烯酶（NG Biotech，法国吉普里）未检测到任何分离株，并且它们无法在选择性显色培养基Carba SMART（意大利佛罗伦萨生物梅里埃公司）上生长。因此，它们逃避了用于快速检测产KPC菌的常规检测。
