Department of Veterinary Internal Medicine, Konkuk University College of Veterinary Medicine, Seoul, South Korea.
Department of Laboratory Medicine, Hallym University College of Medicine, Chuncheon, South Korea.
BMC Vet Res. 2020 Apr 15;16(1):111. doi: 10.1186/s12917-020-02328-0.
Fluoroquinolone agents, such as enrofloxacin and marbofloxacin, are commonly used for pseudomonal infection in veterinary medicine. However, the rate of resistance to fluoroquinolones is rapidly increasing, according to multiple studies in various countries. Point mutations in the quinolone resistance-determining region (QRDR) are closely related to the increased fluoroquinolone resistance of Pseudomonas aeruginosa. The aim of this study was to investigate current antimicrobial susceptibility and fluoroquinolone resistance in P. aeruginosa strains isolated from dogs. The presence of point mutations in the QRDR was confirmed by gyrA and parC polymerase chain reaction and nucleotide sequencing analysis.
A total of 84 nonduplicated P. aeruginosa strains were obtained from 228 healthy dogs (healthy group) and 260 dogs with clinical signs (infected group). Among these isolates, 38 strains from the healthy group were detected in several sample types, whereas 46 strains from the infected group were obtained mostly from dogs' ears with otitis externa (41/260, 15.8%). All strains were resistant to nalidixic acid, while some were also resistant to enrofloxacin (23/84, 27.4%), marbofloxacin (17/84, 20.2%), levofloxacin (12/84, 14.3%), or ciprofloxacin (11/84, 13.1%). Enrofloxacin resistance was significantly higher in strains from the infected group than in those from the healthy group (p < 0.05). Among the 23 fluoroquinolone-resistant strains, 8 and 4 different mutations were detected in the gyrA and parC genes, respectively. Mutations in gyrA were significantly common in the infected group (p < 0.05). Hotspots for the gyrA and parC mutations were Thr83 (34.8%, 8/23) and Pro116 (91.3%, 21/23), respectively. Double and triple mutations were also found in 5 of the strains.
Novel mutations in the gyrA and parC genes were first found in P. aeruginosa isolated from companion dogs in South Korea. These findings suggest that it is important to encourage prudent use of fluoroquinolone antibiotics in canine pseudomonal infection treatment.
氟喹诺酮类药物，如恩诺沙星和马波沙星，常用于兽医治疗假单胞菌感染。然而，根据多个国家的多项研究，氟喹诺酮类药物的耐药率正在迅速上升。喹诺酮类药物耐药决定区（QRDR）的点突变与铜绿假单胞菌氟喹诺酮类药物耐药性的增加密切相关。本研究旨在调查从犬分离的铜绿假单胞菌菌株的当前抗菌药物敏感性和氟喹诺酮类药物耐药性。通过gyrA 和 parC 聚合酶链反应和核苷酸测序分析证实 QRDR 中的点突变的存在。
从 228 只健康犬（健康组）和 260 只具有临床症状的犬（感染组）中获得了总共 84 株非重复的铜绿假单胞菌株。在这些分离株中，健康组的 38 株分离株在几种样本类型中被检测到，而感染组的 46 株分离株主要从患有外耳炎的犬的耳朵中获得（260 只中的 41 只，15.8%）。所有菌株均对萘啶酸耐药，而有些菌株对恩诺沙星（23/84，27.4%）、马波沙星（17/84，20.2%）、左氧氟沙星（12/84，14.3%）或环丙沙星（11/84，13.1%）也有耐药性。感染组的恩诺沙星耐药率明显高于健康组（p<0.05）。在 23 株氟喹诺酮类耐药株中，gyrA 和 parC 基因分别检测到 8 种和 4 种不同的突变。gyrA 中的突变在感染组中更为常见（p<0.05）。gyrA 和 parC 突变的热点分别为 Thr83（34.8%，8/23）和 Pro116（91.3%，21/23）。5 株还发现了双重和三重突变。
首次在韩国的伴侣犬中分离到铜绿假单胞菌，发现了 gyrA 和 parC 基因的新突变。这些发现表明，鼓励在犬类假单胞菌感染治疗中谨慎使用氟喹诺酮类抗生素非常重要。
