Johnson James R, Porter Stephen, Thuras Paul, Castanheira Mariana
Minneapolis Veterans Affairs Healthcare System.
Departments of Medicine and Psychiatry, University of Minnesota, Minneapolis; and.
Open Forum Infect Dis. 2017 May 2;4(2):ofx089. doi: 10.1093/ofid/ofx089. eCollection 2017 Spring.
Extraintestinal infections are increasingly challenging due to emerging antimicrobial resistance, including resistance to extended-spectrum beta-lactams and fluoroquinolones. Sequence type 131 (ST131) is a leading contributor.
Three hundred sixty clinical isolates from across the United States (2011-2012), selected randomly from the SENTRY collection within 3 resistance categories (extended-spectrum cephalosporin [ECS]-reduced susceptibility [RS]; fluoroquinolone-resistant, ESC-susceptible; and fluoroquinolone-susceptible, ESC-susceptible) were typed for phylogroup, sequence type complex (STc), subsets thereof, virulence genotype, O type, and beta-lactamase genes. Molecular results were compared with susceptibility profile, specimen type, age, and sex.
Phylogroup B2 accounted for most isolates, especially fluoroquinolone-resistant isolates (83%). Group B2-derived ST131 and its 30 subclone (divided between 30Rx and 30R1) predominated, especially among ESC-RS and fluoroquinolone-resistant isolates. In contrast, among fluoroquinolone-susceptible isolates, group B2-derived STc73 and STc95 predominated. Within each resistance category, ST131 isolates exhibited more extensive resistance and/or virulence profiles than non-ST131 isolates. ST131-30 was distributed broadly by geographical region, age, and specimen type and exhibited distinctive beta-lactamase genes. Back-calculations indicated that within the source population ST131 accounted for 26.4% of isolates overall (vs 17% in 2007), including 19.8% ST131-30, 13.2% ST131-30R1, and 6.6% each ST131-30Rx and non-30 ST131.
ST131-30, with its ESC resistance-associated 30Rx subset, caused most antimicrobial-resistant infections across the United States in 2011-2012 and, since 2007, increased in relative prevalence by >50%. Focused attention to this strain could help combat the current resistance epidemic.
由于新出现的抗菌药物耐药性，包括对超广谱β-内酰胺类和氟喹诺酮类药物的耐药性，肠外感染正面临越来越大的挑战。序列型131（ST131）是主要原因。
从美国各地（2011 - 2012年）的哨兵监测项目中随机选取360株临床分离株，分为3种耐药类别（超广谱头孢菌素[ECS]敏感性降低[RS]；氟喹诺酮耐药、ECS敏感；氟喹诺酮敏感、ECS敏感），对其进行菌群分型、序列型复合体（STc）、其子集、毒力基因型、O型和β-内酰胺酶基因分型。将分子结果与药敏谱、标本类型、年龄和性别进行比较。
B2菌群占大多数分离株，尤其是氟喹诺酮耐药分离株（83%）。源自B2群的ST131及其30亚克隆（分为30Rx和30R1）占主导地位，尤其是在ECS - RS和氟喹诺酮耐药分离株中。相比之下，在氟喹诺酮敏感分离株中，源自B2群的STc73和STc95占主导地位。在每个耐药类别中，ST131分离株比非ST131分离株表现出更广泛的耐药性和/或毒力谱。ST131 - 30在地理区域、年龄和标本类型上分布广泛，并表现出独特的β-内酰胺酶基因。回溯计算表明，在源人群中，ST131总体占分离株的26.4%（2007年为17%），包括19.8%的ST131 - 30、13.2%的ST131 - 30R1以及各占6.6%的ST131 - 30Rx和非30型ST131。
ST131 - 30及其与ECS耐药相关的30Rx子集在2011 - 2012年导致了美国大部分抗菌药物耐药感染，自2007年以来，其相对流行率增加了50%以上 > 。对该菌株的重点关注有助于应对当前的耐药性流行。
