Effect of Antimicrobial Agents on the Production and Release of Shiga Toxin by Enterotoxaemic <i>Escherichia coli</i> Isolates from Pigs

Abstract

ABSTRACT. Edema disease (ED) of pigs is an enterotoxaemic disease caused by enterotoxaemic Escherichia coli (ETEEC) infection. Antimicrobial therapy for pigs with ED is controversial because it may induce death of sickish piglets. In this study, we investigated the effects in vitro of 7 antimicrobial agents, ampicillin, gentamicin, colistin, bicozamycin, fosfomycin, sulfamethoxazole-trimethoprim and enrofloxacin, on the release and production of shiga toxin (Stx) 2e by ETEEC strains. We found that more Stx 2e accumulated in the bacterial cells than was released into supernatant. Associated with inhibition of cell wall synthesis, the exposure to ampicillin or fosfomycin increased the release of Stx 2e. The production levels of Stx 2e in all antimicrobial-treated cultures were equal to the level in the control or less than in the control. These results suggest that cell wall synthesis inhibitors, such as ampicillin and fosfomycin, may change for the worse in the signs in ETEEC infectious pigs. On the other hand, gentamicin, colistin, bicozamycin and enrofloxac in may be useful for the treatment of pigs with ED. KEY WORDS: antimicrobia, edema disease, enterotoxaemic Escherichia coli, shiga toxin 2e, swine.J. Vet. Med. Sci. 66(8): 899-903, 2004 Edema disease (ED) of the pig has been found throughout the world since ED was first reported in Ireland in 1938 [17]. ED has been a sporadically occurring disease found mainly in post-weaned piglets that causes systemic vascular damage as a result of intestinal infection with shiga toxinproducing Escherichia coli (STEC) [1,2,5]. The STEC is also called enterotoxaemic Escherichia coli (ETEEC) [14]. After ETEEC colonizes in the intestines, shiga toxin (Stx) 2e produced by the ETEEC is absorbed into the capillary vessels and then damages the endothelial cells [1,2,5]. The manifestations of ED include palpebral edema, neurological impairment, lateral recumbence and sudden death [1,2]. The speed of onset and severity of clinical signs and gross pathological lesions are related to the dose of the toxin. Intervals between injection and onset of the disease vary from 7 to 28 hr, the mean time to death being from 24 to 42 hr [2]. Classical ED has been seen to occur sporadically and subside spontaneously [1,2,8,11]. Recently, ED has tended to persist and spread, causing great economic damage to pig farmers [20,21,24].Antimicrobial administration has been used as one of the most common treatments for the eradication of STEC from the intestines of humans and animals [12,14,16,22]. Nevertheless, some antimicrobial agents have been reported to increase the release of Stxs from enterohemorrhagic Escherichia coli (EHEC) associated with enterohemorrhagic colitis and hemolytic uremic syndrome of humans in vitro [4,10,13,22,23]. In ED affected farms, deaths of piglets associated with antimicrobial treatment have increased in number [7,24]. Until now, however, there has been no investigation to determine the effect of antimicrobial agents on the production and release of Stx 2e by ETEEC.In ...

Different Effects of Six Antibiotics and Ten Traditional Chinese Medicines on Shiga Toxin Expression byEscherichia coliO157:H7

“…However, it was reported [44] that tigecyline reduced stx 2 expression, while another study [19] reported that bicozamycin reduced stx 2 expression, which disagreed with other work [16]. The data in Figure 2 shows that tetracycline had only a weak inductive effect on stx 2 gene expression, which agreed with a previous report [16].…”

“…A previous study [16] suggested that they do not induce stx gene expression, whereas another study [20] showed that ceftazidime did not affect stx gene expression whereas panipenem (PAPM) greatly suppressed stx gene expression. Other studies [17, 19] have shown that cefotaxime and meropenem [44] do not affect stx gene expression. By contrast, it was reported [17, 18] that ampicillin increased stx gene expression.…”

Experimental Infection of Enterotoxemic Escherichia coli Associated with Porcine Edema Disease and its Pathologic Characteristics in the Intestine

“…However, the use of antimicrobials has resulted in the development of antimicrobialresistant STEC on Japanese farms [8,22]. Furthermore, the use of some antimicrobials, such as ampicillin and fosfomycin, is a possible cause for the aggravation of ED symptoms [23]. Accordingly, the use of materials other than antimicrobials is requested for the prevention or treatment of ED, most particularly on farms where antimicrobial-resistant STEC has been identified.…”

Characterization of inducible stx2-positive Escherichia coli O157:H7/H7- strains isolated from cattle in France

“…1999; Yoh et al. 1999), with the exception of opposite effects in rare examples (one strain in each case: one O139 strain from pig, (Uemura et al. 2004) and one human O157:H7 strain (Grif et al.…”