Pathotyping and antibiotic resistance of porcine enterovirulent Escherichia coli strains from Switzerland (2014–2015)

Abstract

A total of 131 porcine E. coli were isolated in 2014 and 2015 from the gut of 115 pigs raised in Switzerland and suffering from diarrhea. The isolates were tested for antibiotic resistance, serotypes, virulence factors and genetic diversity. Serotypes were assigned by agglutination tests and virulence genes were identified by polymerase chain reaction (PCR). Antibiotic resistance profile was determined by the measurement of the MIC of 14 antibiotics and by the detection of the corresponding genes using microarray and PCR approaches. Genetic diversity was determined by repetitive palindromic PCR (rep- PCR) revealing a heterogenous population. Half of the E. coli isolates possessing virulence factors could not be assigned to any of the 19 serotypes tested, but contained toxins and adhesins similarly to the sero-typable E. coli isolates. The most prevalent E. coli serotypes found were K88ac (18%), O139:K82 (6%), O141:K85ac (5%), O108:K`V189` (5%), O119:K`V113` (3%) and O157:K`V17` (2%). The combination of toxins EAST-1, STb and LT-I and adhesin F4 characterizing ETEC was the most frequent. The shigatoxin Stx2e (STEC) and intimin Eae (EPEC) were also detected, but less frequently. Seventy percent of the isolates were resistant to at least one antibiotic and 29% were resistant to more than 3 antibiotics. Isolates exhibited resistance to tetracycline (50%) associated to resistance genes tet(A), tet(B) and tet(C), sulfamethoxazole (49%) [sul1, sul2 and sul3], trimethoprim (34%) [dfr], nalidixic acid (29%), ampicillin (26%) [blaTEM-1], gentamicin (17%) [aac(3) -IIc, aac(3) -IVa and aac(3) -VIa], chloramphenicol (17%) [catAI and catAIII], and ciprofloxacin (8%) [mutations in GyrA (S83L) and ParC (S80I)]. All isolates were susceptible to 3rd generation cephalosporins, carbapenems, colistin and tigecycline. Pathogenic E. coli isolates from pigs in Switzerland could frequently not be assigned to a known serotype even if they contained diarrhea-causing virulence factors. They also harbor resistance mechanisms conferring resistance to antibiotics which are commonly used in pig husbandry, except for colistin. A careful identification of the causative agent and antibiotic susceptibility testing is highly recommended for targeted therapy and prudent use of antibiotics.

Prevalence of Virulence Genes and Antimicrobial Resistances in E. coli Associated with Neonatal Diarrhea, Postweaning Diarrhea, and Edema Disease in Pigs from Austria

“…Our standard microbiological diagnostic procedures do not test resistances to trimethoprim and sulfamethoxazole separately since both are only licensed in combination for the application in pigs. Resistance rates towards trimethoprim-sulfamethoxazole of porcine E. coli were relatively high in our investigations, which goes along with the results of other European surveys [19,23]. Similar findings were also reported in Germany, although the number of isolates with resistances to trimethoprim-sulfamethoxazole has slightly decreased over the past 14 years [24].…”

Reviving post-mortem diagnostics as a tool to increase porcine herd health and strengthen early detection of pig diseases – the PathoPig project 2014-2016

“…housing, hygiene) and therefore no specific etiology was detected. Diarrhea linked to infection with E. coli remains one of the most important diseases in suckling piglets and weaners in Switzerland (Graage et al, 2015;Brand et al, 2017). A similar situation is reported from Austria (Schoder, pers.…”

“…As a beneficial effect, this enables research on various infectious agents causing health problems in pigs. In the case of PathoPig studies on the involvement and zoonotic potential of endoparasites in pigs (Schubnell et al 2016,) pathogenic E. coli (Schneeberger et al 2017) and antibiotic resistance (Brand et al 2017) have already been performed.…”

Invited review: Tannins as a potential alternative to antibiotics to prevent coliform diarrhea in weaned pigs

“…The extensive use of in-feed antimicrobials has been associated with an increasing incidence of antimicrobial resistance, with 70% of the pathogenic E. coli isolated from Swiss pig farms displaying resistance to at least one antimicrobial (Brand et al, 2017). Across Europe, the situation is similar.…”