Baldo Valentina, Salogni Cristian, Giovannini Stefano, D'Incau Mario, Boniotti Maria Beatrice, Birbes Laura, Pitozzi Alessandra, Formenti Nicoletta, Grassi Andrea, Pasquali Paolo, Alborali Giovanni Loris
Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna "Bruno Ubertini", Brescia, Italy.
Department of Veterinary Public Health and Food Safety, Istituto Superiore di Sanità, Rome, Italy.
Front Vet Sci. 2020 Sep 18;7:545818. doi: 10.3389/fvets.2020.545818. eCollection 2020.
Shiga toxin type 2e (Stx2e) is the causative factor of diarrhea and edema in swine. The aims of this study were to determine the prevalence of Stx2e-producing isolates and to characterize isolates from clinical cases of pig colibacillosis and healthy swine. During the 11 years of the study (2006-2017), a total of 233 Stx2e-producing isolates were detected-230 out of 2,060 (11.16%) isolated from diseased pigs and 3 out of 171 (1.75%) from healthy swine. Stx2e-producing isolates were indeed more present in clinical colibacillosis cases than in healthy pigs ( = 0.0002). The predominant serogroup was O139 (79.82%) and the most common fimbrial factor present in these isolates was F18 (177 isolates), followed by F6 (5 isolates). The enterotoxins LTI, STa, and STb were detected in 10.43, 41.73, and 48.26% of the isolates, respectively. The predominant virotypes F18-Stx2e and -STa-STb-Stx2e were similarly present in weaners (33.33 and 35.52%) and finishers (38.30 and 25.53%). Among isolates from diseased pigs, O139 and F18 were the more frequently identified serogroup and virulence factor, respectively. Of the tested 230 Stx2e-producing isolates isolated from diseased pigs, 29 (12.60%) harbored genes encoding ESBL, particularly TEM (79.30%), CTX-M1 (17.20%), and CMY-2 (3.40%). Antimicrobial resistance to tetracycline was the most common characteristic (98.25%), followed by ampicillin (93.91%), cephalotin (90.43%) and trimethoprim/sulfamethoxazole (82.17%). Our results showed that Stx2e-producing were more frequently associated with clinical forms of colibacillosis, with minimal probability to isolate these isolates from healthy pigs.
2型志贺毒素e（Stx2e）是猪腹泻和水肿的致病因素。本研究的目的是确定产Stx2e分离株的流行率，并对猪大肠杆菌病临床病例和健康猪的分离株进行特征分析。在研究的11年（2006 - 2017年）期间，共检测到233株产Stx2e分离株，其中2060株患病猪中有230株（11.16%），171株健康猪中有3株（1.75%）。产Stx2e分离株在临床大肠杆菌病病例中确实比健康猪中更常见（P = 0.0002）。优势血清型为O139（79.82%），这些分离株中最常见的菌毛因子是F18（177株），其次是F6（5株）。分别在10.43%、41.73%和48.26%的分离株中检测到肠毒素LTI、STa和STb。优势病毒型F18 - Stx2e和 - STa - STb - Stx2e在断奶仔猪（33.33%和35.52%）和育肥猪（38.30%和25.53%）中出现的比例相似。在患病猪的分离株中，O139和F18分别是最常鉴定出的血清型和毒力因子。在从患病猪分离的230株产Stx2e分离株中，29株（12.60%）携带编码ESBL的基因，尤其是TEM（79.30%）、CTX - M1（17.20%）和CMY - 2（3.40%）。对四环素的耐药性是最常见的特征（98.25%），其次是氨苄青霉素（93.91%）、头孢噻吩（90.43%）和甲氧苄啶/磺胺甲恶唑（82.17%）。我们的结果表明，产Stx2e分离株与大肠杆菌病的临床形式更常相关，从健康猪中分离到这些分离株的可能性极小。
