PREVALENCE OF ESCHERICHIA COLI O157:H7 AND THE PRESENCE OF TOXIN GENES IN BUFFALO FECES AND MILK

Abstract

Escherichia coli (E. coli) strains that produce Shiga toxin (stx) are among the most important causative agents of foodborne diseases. Cattle are the main reservoir of bacteria that can be transmitted to humans through the contaminated food chain. While Novobiocin-supplemented Tryptone Soy Broth (TSB) was used for bacterial pre-enrichment, the homogenate was first inoculated onto Cefixime Tellurite Sorbitol-MacConkey (CT-SMAC) agar and then onto 4-methylumbelliferyl-β-D-glucuronide (MUG)–Violet Red Bile Agar (VRBA) medium, respectively. Conventional and latex agglutination test methods identified colonies that did not ferment the sorbitol that grew here. Sorbitol-negative E. coli was detected in 32 (29.62%) of the buffalo feces samples and 23 (21.29%) of the raw milk samples. While the O157 antigen was detected in 9 (8.33%) of stool samples and 3 (2.77%) of raw milk samples, the H7 antigen was not found. With real-time Polymerase Chain Reaction, stx toxin was observed in 21 (18.44%) stool samples and 12 (11.11%) raw milk samples. Despite the absence of the H7 antigen in all of the samples studied, the presence of the O157 antigen and Shiga toxin-producing E. coli (STEC) toxin was detected at a high rate. To ensure the raw milk quality, the personnel working effectively and continuously in the milk production line should be trained on food safety/health and hygiene practices. In addition, stricter regulations and strategies should be determined to protect public health.

Razširjenost bakterije Escherichia coli O157:H7 in prisotnost toksinskih genov v bizonjih iztrebkih in mleku

Izvleček: Sevi Escherichie coli (E. coli), ki proizvajajo toksin šiga (stx), so med najpomembnejšimi povzročitelji bolezni, ki se prenašajo s hrano. Govedo je glavni rezervoar bakterij, ki se lahko prenesejo na ljudi v kontaminirani prehranski verigi. Medtem ko je bilo za predhodno obogatitev uporabljeno triptonsko sojino gojišče (TSB), dopolnjeno z novobiocinom, je bil homogenat najprej nacepljen na agar CT-SMAC (Cefixime Tellurite Sorbitol-MacConkey) in nato na gojišče VRBA-MUG (Violet Red Bile Agar – VRBA in 4-metilumbelliferil-β-D-glukuronid – MUG). S konvencionalnimi metodami in metodami lateksne aglutinacije so bile ugotovljene bakterijske kolonije, ki niso fermentirale sorbitola. Sorbitol-negativna E. coli je bila odkrita v 32 (29,62 %) vzorcih bivoljih iztrebkov in 23 (21,29 %) vzorcih surovega mleka. Antigen O157 je bil odkrit v 9 (8,33 %) vzorcih blata in 3 (2,77 %) vzorcih surovega mleka, antigen H7 pa v nobenem. S polimerazno verižno reakcijo v realnem času je bil toksin stx ugotovljen v 21 (18,44 %) vzorcih blata in 12 (11,11 %) vzorcih surovega mleka. Kljub odsotnosti antigena H7 v vseh proučevanih vzorcih je bila v veliki meri ugotovljena prisotnost antigena O157 in E. coli, ki proizvaja toksin šiga (STEC). Za zagotavljanje kakovosti surovega mleka je treba osebje, ki učinkovito in neprekinjeno dela v proizvodnji mleka, usposobiti za higieno in varnost živil. Poleg tega je treba določiti strožje predpise in strategije za varovanje javnega zdravja.

Ključne besede: E. coli O157:H7; gen za toksin stx; bizonji iztrebki; bizonje surovo mleko