Escherichia coli is one of the major causative infectious agents of diarrhea in preweaning and postweaning pigs and leads to a large economic loss worldwide. However, there is limited information on the distribution and virulence genes in E. coli isolated from diarrheic piglets, which also applies to the current status of pig farms in Korea. To investigate the prevalence of virulence-associated genes in E. coli related to diarrhea in piglets, the rectal swab samples of diarrheic piglets were collected from Seoul National University’s veterinary pathological department between 2022 and 2023. E. coli strains were identified using the VITEK II system. Two sets of multiplex PCRs and one single PCRs used to detect 10 E. coli virulence genes. As a result, a total of 145 E. coli isolates were identified encoding one or more of the virulence genes. Among them, the prevalence of individual virulence gene was as follows, piglets virulence genes were STa 58.6%(85/145), STb 22.1%(32/145), LT 15.2%(22/145), EAST1 24.8%(36/145), Stx2e 6.9%(10/145), F4 31.7%(46/145), F5 1.4%(2/145), F6 11.7%(17/145), F18 4.1%(6/145), and F41 0.7%(1/145) respectively. These results suggest that E. coli disease in piglets may not be associated with a single toxin or a major gene combination, but with more varied and complex toxins and their combinations in Korea.

Although most strains of escherichia coli (E. coli) are harmless, some serotypes can cause serious food poisoning in humans. It is very difficult to eliminate E. coli from our lives. Here we show that E. coli can be eliminated by hydroxyapatite (HAp). Because HAp has a positive charge, the material and E. coli are attracted through electrostatic interactions. Additionally, because the surface of HAp is porous, it enters the pores of the HAp surface removing them from the environment. The amount of adsorption was observed to increase over time, and the zeta potential value of the material tended to be similar to that of E. coli. This phenomenon is thought to have zeta potential similar to that of E. coli as it is adsorbed onto the HAp surface over time. E. coli stained with crystal violet was spread on a glass slide and HAp porous sol powder was dropped to remove the E. coli. We expect that this analysis will open a new direction for antibacterial materials.

소 유방염 관련 대장균(BMEC)은 생산되는 우유의 양과 품질을 변화시키고 도태율을 높임으로써 전 세계 낙농 산 업에 심각한 재정적 손실을 초래할 수 있는 주요 원인 물 질로 간주된다. 연구자, 수의사, 농부가 가장 효과적인 치 료법과 진단 기술을 이해하고 결정하는 것은 젖소 유방염 을 극복하는데 중요하다. 특히 무증상 혹은 준임상형 유 방염의 경우, 소는 뚜렷한 증상을 보이지 않고, 장기간에 걸쳐 겉보기에 정상적인 우유를 계속 분비하여 원인 병원 체인 대장균이 무리 내에서 감염을 퍼뜨릴 수 있다. 유방 염 예방을 위해서는, 병원균의 유방 내 침입, 감염 확립, 유방의 염증의 3단계 병인 과정에 대한 이해가 필수적이 다. 지금까지 대장균 유방염의 임상적 중증도에 기여하는 독성 인자와 병원성 사이에 명확한 상관관계가 발견되지 않았다. 다제내성 대장균과 새로운 내성 기전의 진화는 유 방염 치료에 항생제를 광범위하게 사용하고 있기 때문에 문제시 되고 있는 실정이다. 따라서 BMEC 치료의 효능 을 향상시키기 위해서는 대체제 발굴이 중요하다. 지난 30 년 동안 소 유방염의 역학 조사를 위해 다양한 유전자형 분석 기술이 사용되었다. 이러한 연구는 BMEC 계통 간 의 진화 관련성 뿐 아니라 기원, 전염 경로, 개체군 구조 에 대한 이해를 크게 향상시켰다. 따라서 본 리뷰에서는 BMEC의 전반적 개요를 제공하여 병인, 유전적 관계, 발 병 기전, 관리 및 질병 통제를 위한 새로운 치료 옵션에 대한 통찰력을 제공하고자 한다.

Pathogenic Escherichia coli strains are known to cause edema disease (ED) and postweaning diarrhea (PWD) in piglets. Although the exact mechanisms of pathogenicity that lead to ED-PWD remain to be elucidated, we investigated whether another E. coli adhesin, the plasmid-encoded adhesin involved in diffuse adherence (AIDA) might also be present in ED-PWD-causing E. coli isolates. It was showed that E. coli strains attach to HEp-2 cell assay in three different patterns. Twenty-two isolates were from faeces of preweaned pigs and 36 isolates were from faeces of postweaned pigs. The base sequences for specific oligonucleotide primers of PCR used in this study were constructed based on the regions of conserved sequences between forward (5′-3′) ACAGTATCATATGGAGCCA and reverse (5′-3′) TGTGCGCCAGAACTATTA. Product size was 585 base pairs. A total of 58 AIDA-positive E. coli were used for cell adherence pattern analysis of HEp-2 cell assay. Forty three isolates showed three distinct patterns that were localized adherence (LA), diffuse adherence (DA) and aggregative adherence (AA) patterns respectively. But fifteen isolates were nonadherent. LA (14 isolates) pattern was the most common, followed by DA (13 isolates) and AA (9 isolates) pattern. And three isolates showed a combination of the LA and AA patterns and 4 isolates showed a combination of the DA and AA patterns. Escherichia coli strains that cause nonbloody diarrhea in infants are known to present three distinct patterns of adherence to epithelial cells, namely, localized (LA), diffuse (DA), and aggregative (AA) adherence.

This study investigated the inactivation effect of intense pulsed light (IPL) on various packaging films. The UV-C transmittance irradiance varied depending on the packaging materials, with the control group having an irradiance of 3.959 W/m2. For the thinnest layer of 30 mm, polypropylene (PP) had an irradiance of 3.258 W/m2, polyethylene (PE) had an irradiance of 3.193 W/ m2, and oriented polypropylene (OPP) had an irradiance of 3.200 W/m2. In contrast, polyethylene terephthalate (PET) exhibited a significantly lower irradiance of only 0.065 W/m2 for its thinnest film thickness of 100 mm. The light transmittance of the packaging materials was similar, with values of 91.3%, 89.7%, and 89.5% for PP, PE, and OPP, respectively. In contrast, PET exhibited a significantly lower light transmittance of 1.8% compared to the other packaging materials. These findings have practical implications for the food packaging industry. According to the packaging film material, the sterilization effects showed that the E. coli sterilization effect of PP was the highest, followed by PE and OPP, which were similarly effective. At the same time, PET exhibited the lowest sterilization effect. For PP film with a thickness of 30 mm, a 6.2 log reduction in the E. coli population was observed after 20 s of IPL treatment. Ultimately, inactivation was achieved after 60 seconds. Both PE and OPP films, which had a thickness of 30 mm, showed a 5.9 log reduction in E. coli after 30 s of IPL treatment, followed by complete inactivation after 60 s. The inactivation rate for PP, PE, and OPP films showed minimal variation regardless of thickness, although it gradually decreased with increasing thickness. For PET, achieving a 1 log reduction in E. coli required 180 s of IPL treatment at 100 mm thickness and 210 s at 120 mm thickness, indicating the influence of film thickness on inactivation rate. Even after 300 s of IPL treatment, the inactivation effect for PET remained around 1.5 log, the lowest among all packaging film materials.

본 연구에서는 시가독소 생성 대장균(STEC)을 검출하 기 위해 식품공전의 polymerase chain reaction (PCR)검사 법과 loop-mediated isothermal amplification (LAMP)를 비 교하였다. PCR 및 LAMP의 검출 한계(LOD) 및 정량화 한계(LOQ), 민감도, 특이성 및 효율성을 평가하기 위해 다 양한 식품에 STEC를 접종하였다. LOD는 PCR의 경우 104 CFU/mL 이하, LAMP의 경우 103 CFU/mL 이하로 측정되 었다. LOQ 값은 PCR과 LAMP 간에 차이가 없었다. 그러 나 4가지 식품군에서 민감도는 양념육이 최대 11.1%, 간 소고기가 최소 8.1% 차이가 났다. LAMP는 네 가지 음식 유형 모두에 대해 높은 민감도와 100% 특이도를 보였다. 따라서 LAMP는 식품 유형에 따라 검출률이 비슷하고 특 이도와 민감도가 식품공전 PCR보다 우수하기 때문에 STEC 에 대한 신뢰할 수 있는 분자 검출 방법이다.

Enteropathogenic Escherichia coli (EPEC) have developed survival strategies to evade host defense systems. The intracellular level of guanosine tetraphosphate (ppGpp) controlled by RelA and SpoT can mediate immune evasion of EPEC. However, the impact of ppGpp-defective EPEC infection on phagocytes remains unknown. In this study, we report that disrupting relA and spoT of EPEC E2348/69 strain promotes its phagocytosis in porcine macrophages. Our experimental analysis showed that both uptake and killing of an E2348/69 ΔrelAΔspoT mutant by macrophages were increased compared to those of wildtype strain. These results suggest that ppGpp plays an essential role in evading phagocytosis during EPEC pathogenesis.

Enteropathogenic Escherichia coli (EPEC) is one of the etiological agents that causes diarrhea in weaning pigs. In this study, we report that mutating both relA and spoT genes in EPEC E2348/69 can promote bacterial clearance in porcine gastrointestinal tract (GIT). Our experimental analyses showed that an E2348/69 ΔrelAΔspoT mutant strain was not detected in porcine feces after 1 day post-infection (dpi), whereas its parental strain was continuously detected in porcine feces within 10 dpi. Histologic assessment revealed that the mutant strain was unable to induce moderate pathologic lesions in porcine GIT when compared to those with the wildtype strain. Taken together, our data suggest that the relA and spoT genes in EPEC play an important role in bacterial survival and pathogenesis in porcine GIT.

Avian colibacillosis is severe respiratory and systemic disease caused by avian pathogenic E. coli (APEC). The disease results in economic loss because of early mortality and reduced productivity in chickens. Several antimicrobials have been used extensively for reducing the losses due to colibacillosis. β-lactams, including penicillin derivatives, cephalosporins, and carbapenems, are one of the most commonly used, clinically important antibiotics. In this study, the phenotypic and genotypic characteristics of 14 CTX-M-producing APEC were investigated. Two types of CTX-M genes were detected, namely, CTX-M-1 gene (8 isolates) and CTX-M-15 gene (6 isolates), and all CTX-M-producing APEC were multidrug resistant. Moreover, 10 of the 14 CTX-M-producing E. coli isolates carried the TEM-1 gene, and 8 of the 14 isolates contained class 1 integrons. The following three different gene cassette arrangements were identified in six isolates: aadA1 (n=2), dfrA1 (n=2), and aadA1+dfrA1 (n=2). All CTX-M-producing APEC isolates harbored IncF plasmids, including F, FII, FIA, and FIB. CTX-M-1 gene was located on I1, F, and FIB, and CTX-M-15 gene on FII, FIA, and FIB. The findings from this study indicate that E. coli carrying CTX-M gene are circulating in the broiler poultry industry. Comprehensive surveillance and persistent monitoring of the integrated broiler operations are warranted to prevent the dissemination of resistant isolates.

Long-term non-surgical contraceptive methods for cats, especially community cats, are of global interest for cost-effective and humane reasons. This study aimed to investigate the effectiveness of a gonadotropin-releasing hormone (GnRH)-based vaccine for immunocontraception and to confirm its safety in intact female cats. Recombinant Salmonella typhimurium flagellin fljB (STF2)-GnRH protein was expressed in Escherichia coli. We divided female cats into vehicle control group (n = 4) and two experimental groups (100 μg injection group [n = 7] and 1000 μg injection group [n=7]), and immunized them twice intramuscularly (0.2 mL/cat at zero week and 4 weeks later into the other leg). Breeding trials started on day 120. All control cats (n = 4/4), 71% of the 100 μg injection group (n = 5/7), and 57% of the 1000 μg injection group (n = 4/7) became pregnant within 203 days after the introduction of male cats. The 1000 μg injection group had significantly a longer median time to conception following treatment (166 days) than the control (17 days, p < 0.05). Average litter size was significantly lower in the 1000 μg GnRH-vaccinated cats (2.8 ± 0.7) than in the control cats (4.5 ± 0.5, p < 0.05). Injection site reactions were not observed in any cat. The E. coli-expressed STF2-GnRH vaccine did not provide contraception in a sufficient proportion of the cats. However, it might be effective to suppress fertility through infertility vaccines before inducing permanent infertility through the trap-neuter-return.