Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, 65000, Thailand.
Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand.
Poult Sci. 2022 Oct;101(10):102090. doi: 10.1016/j.psj.2022.102090. Epub 2022 Aug 1.
This longitudinal study aimed to determine the fecal shedding pattern and characterize Salmonella enterica and mcr-positive Escherichia coli from meat-type ducks raised in an open-house system in Thailand. Fecal samples (n = 1,475) were collected from ducks over a 6-month period. Overall, the detection rate of S. enterica was 5.4% and the highest fecal shedding rate was noted in 4-day-old ducklings (28.8%). Then, S. enterica shedding decreased to 10, 8, 4.7, and 0.7% when ducks reached the ages of 10 d, 17 d, 3 wk, and 4 wk, respectively. Seventy-nine isolates were recovered and Salmonella Amsterdam was the predominant serovar (79.7%). With respect to colistin-resistant E. coli, mcr-positive E. coli (colistin MICs = 8-16 μg/mL) was noted in ducks at the ages of 16 wk (6.0%) and 24 wk (18.7%). mcr-1 was the most common (75.7%), followed by mcr-3 (13.5%), and mcr-1 and mcr-3 co-carriage (10.8%). Most S. enterica isolates were susceptible to antibiotics and multidrug resistant (MDR) was found in only a single isolate. However, as many as 89.2% of mcr-positive E. coli were defined as MDR. Almost all S. enterica isolates (97.5-100%) carried several virulence genes involving in invasion, intracellular survival, and iron metabolism. Pulsed Field Gel Electrophoresis revealed that several mcr-positive E. coli isolates were clonally unrelated. Conjugative transfer of mcr-1, mcr-3 as well as co-transfer of mcr-1 and mcr-3 was observed with the frequencies ranging from 10 to 10. All mcr-1 resided on IncI2, while mcr-3 was associated with IncF and IncX4 plasmids. Our study provides the evidence of fecal shedding pattern of S. enterica and mcr-positive E. coli from meat-type ducks, highlighting the importance of duck farming in the dissemination of pathogenic bacteria that are potentially hazardous to human.
本纵向研究旨在确定泰国开放式饲养肉鸭中肠道沙门氏菌和 mcr 阳性大肠杆菌的粪便排出模式，并对其特征进行分析。在 6 个月的时间里，采集了 1475 只鸭的粪便样本。总体而言，肠道沙门氏菌的检出率为 5.4%，4 日龄雏鸭的粪便排出率最高（28.8%）。随后，10 日龄、17 日龄、3 周龄和 4 周龄鸭的肠道沙门氏菌排出率分别降至 10%、8%、4.7%和 0.7%。共分离出 79 株菌，其中血清型为阿姆斯特丹沙门氏菌的比例最高（79.7%）。耐黏菌素大肠杆菌中，16 周龄（6.0%）和 24 周龄（18.7%）鸭的 mcr 阳性大肠杆菌（黏菌素 MIC 值为 8-16μg/ml）。mcr-1 最为常见（75.7%），其次是 mcr-3（13.5%），mcr-1 和 mcr-3 共同携带（10.8%）。大多数肠道沙门氏菌分离株对抗生素敏感，只有一株分离株表现为多重耐药。然而，多达 89.2%的 mcr 阳性大肠杆菌被定义为多重耐药。几乎所有肠道沙门氏菌分离株（97.5-100%）都携带几种与侵袭、细胞内生存和铁代谢有关的毒力基因。脉冲场凝胶电泳显示，一些 mcr 阳性大肠杆菌分离株之间不存在克隆相关性。mcr-1、mcr-3 的接合转移以及 mcr-1 和 mcr-3 的共同转移频率范围为 10-10-6。所有 mcr-1 均位于 IncI2 上，而 mcr-3 与 IncF 和 IncX4 质粒有关。本研究提供了肉鸭肠道沙门氏菌和 mcr 阳性大肠杆菌粪便排出模式的证据，强调了鸭养殖在传播对人类潜在危险的致病性细菌方面的重要性。
