Quadram Institute Bioscience, Norwich Research Park, Norwich, UK.
University of East Anglia, Norwich, UK.
BMC Microbiol. 2024 Jan 11;24(1):20. doi: 10.1186/s12866-023-03153-9.
Pseudomonas species are common on food, but their contribution to the antimicrobial resistance gene (ARG) burden within food or as a source of clinical infection is unknown. Pseudomonas aeruginosa is an opportunistic pathogen responsible for a wide range of infections and is often hard to treat due to intrinsic and acquired ARGs commonly carried by this species. This study aimed to understand the potential role of Pseudomonas on food as a reservoir of ARGs and to assess the presence of potentially clinically significant Pseudomonas aeruginosa strains on food. To achieve this, we assessed the genetic relatedness (using whole genome sequencing) and virulence of food-derived isolates to those collected from humans.
A non-specific culturing approach for Pseudomonas recovered the bacterial genus from 28 of 32 (87.5%) retail food samples, although no P. aeruginosa was identified. The Pseudomonas species recovered were not clinically relevant, contained no ARGs and are likely associated with food spoilage. A specific culture method for P. aeruginosa resulted in the recovery of P. aeruginosa from 14 of 128 (11%) retail food samples; isolates contained between four and seven ARGs each and belonged to 16 sequence types (STs), four of which have been isolated from human infections. Food P. aeruginosa isolates from these STs demonstrated high similarity to human-derived isolates, differing by 41-312 single nucleotide polymorphisms (SNPs). There were diverse P. aeruginosa collected from the same food sample with distinct STs present on some samples and isolates belonging to the same ST differing by 19-67 SNPs. The Galleria mellonella infection model showed that 15 of 16 STs isolated from food displayed virulence between a low-virulence (PAO1) and a high virulence (PA14) control.
The most frequent Pseudomonas recovered from food examined in this study carried no ARGs and are more likely to play a role in food spoilage rather than infection. P. aeruginosa isolates likely to be able to cause human infections and with multidrug resistant genotypes are present on a relatively small but still substantial proportions of retail foods examined. Given the frequency of exposure, the potential contribution of food to the burden of P. aeruginosa infections in humans should be evaluated more closely.
假单胞菌属是食物中的常见菌，但它们在食物中对抗菌药物耐药基因（ARG）负荷的贡献，或者作为临床感染源的作用尚不清楚。铜绿假单胞菌是一种机会致病菌，可引起广泛的感染，由于该物种常携带的内在和获得性 ARG，因此通常难以治疗。本研究旨在了解假单胞菌作为食物中 ARG 储存库的潜在作用，并评估食物中是否存在具有潜在临床意义的铜绿假单胞菌菌株。为了实现这一目标，我们评估了食物分离株与从人类收集的分离株的遗传相关性（使用全基因组测序）和毒力。
一种非特异性的假单胞菌培养方法从 32 个零售食品样本中的 28 个（87.5%）中回收了该细菌属，尽管没有鉴定出铜绿假单胞菌。回收的假单胞菌种没有临床意义，不含有 ARG，可能与食物腐败有关。一种针对铜绿假单胞菌的特定培养方法从 128 个零售食品样本中的 14 个（11%）中回收了铜绿假单胞菌；分离株每个含有 4 到 7 个 ARG，属于 16 个序列型（ST），其中 4 个已经从人类感染中分离出来。来自这些 ST 的食品铜绿假单胞菌分离株与来自人类的分离株高度相似，仅相差 41-312 个单核苷酸多态性（SNP）。从同一样品中采集到了不同的铜绿假单胞菌，有些样本存在不同的 ST，而属于同一 ST 的分离株相差 19-67 个 SNP。大蜡螟感染模型表明，从食物中分离出的 16 个 ST 中的 15 个显示出介于低毒力（PAO1）和高毒力（PA14）对照之间的毒力。
本研究中检查的食品中最常回收的假单胞菌不携带 ARG，更可能在食物腐败中发挥作用，而不是感染。在检查的零售食品中，存在相对较小但仍相当大比例的能够引起人类感染且具有多药耐药基因型的铜绿假单胞菌分离株。鉴于接触的频率，应更密切地评估食物对抗菌药物耐药铜绿假单胞菌感染负担的贡献。
