Detection of enterotoxigenic K99 (F5) and F41 from fecal sample of calves by molecular and serological methods

Schizochytrium sp. and lactoferrin supplementation alleviates Escherichia coli K99-induced diarrhea in preweaning dairy calves

Calf diarrhea, a common disease mainly induced by Escherichia coli infection, is one of the main reasons for nonpredator losses. Hence, an effective nonantibacterial approach to prevent calf diarrhea has become an emerging requirement. This study evaluated the microalgae Schizochytrium sp. (SZ) and lactoferrin (LF) as a nutrient intervention approach against E. coli O101:K99-induced preweaning calve diarrhea. Fifty 1-d-old male Holstein calves were randomly divided into 5 groups (n = 10): (1) control, (2) blank (no supplement or challenge), (3) 1 g/d LF, (4) 20 g/d SZ, or (5) 1 g/d LF plus 20 g/d SZ (LFSZ). The experimental period lasted 14 d. On the morning of d 7, calves were challenged with 1 × 1011 cfu of E. coli O101:K99, and rectum feces were collected on 3, 12, 24, and 168 h postchallenge for the control, LF, SZ, and LFSZ groups. The rectal feces of the blank group were collected on d 14. Data were analyzed using the mixed procedure of SAS (version 9.4; SAS Institute Inc.). The E. coli K99 challenge decreased the average daily gain (ADG) and increased feed-to-gain ratio (F:G) and diarrhea frequency (control vs. blank). Compared with the control group, the LFSZ group had a higher ADG and lower F:G, and the LFSZ and SZ groups had lower diarrhea frequency compared with the control group. In addition, the LFSZ and SZ groups have no differences in diarrhea frequency compared with the blank group. Compared with the control group, the blank group had lower serum nitric oxide (NO), endothelin-1, d-lactic acid (D-LA), and lipopolysaccharide (LPS) concentrations, as well as serum IgG, IL-1β, IL-6, IL-10, and TNF-α levels on d 7 and 14. On d 7, compared with the control group, all treatment groups had lower serum NO level, the SZ group had a lower serum D-LA concentration, and the LF and LFSZ groups had lower serum LPS concentration. On d 14, compared with the control group, the fecal microbiota of the blank group had lower Shannon, Simpson, Chao1, and ACE indexes, the LFSZ group had lower Shannon and Simpson indexes, the SZ and LFSZ groups had a higher Chao1 index, and all treatment groups had a higher ACE index. In fecal microbiota, Bifidobacterium and Actinobacteria were negatively associated with IL-10 and d-lactate, while Akkermansia was negatively associated with endothelin-1 and positively correlated with LPS, fecal scores, and d-lactate levels. Our results indicated that LF and SZ supplements could alleviate E. coli O101:K99-induced calf diarrhea individually or in combination. Supplementing 1 g/d LF and 20 g/d SZ could be a potential nutrient intervention approach to prevent bacterial diarrhea in calves.

Sodium butyrate supplementation impacts the gastrointestinal bacteria of dairy calves before weaning

The objective of this study was to systematically investigate how sodium butyrate (SB) affects the gastrointestinal bacteria in newborn calves at different stages before weaning. Forty female newborn Holstein calves (4-day-old, 40 ± 5 kg of body weight) were randomly divided into four groups; each group was supplemented with four SB doses: 0, 15, 30, and 45 g/day (ten replicates) in SB0, SB15, SB30, and SB45 groups, respectively. SB was fed with milk replacer from day 4 to day 60. Rumen fluid and feces were collected on days 2, 14, 28, 42, and 60 for 16S rRNA high-throughput sequencing. Data were analyzed in a complete randomized design and analyzed on the online platform of Majorbio Cloud Platform. The results showed that SB significantly increased the α-diversity in feces, especially Shannon and Chao indices in SB45 and SB30 at day 60 more than in SB15 (P < 0.05). Additionally, SB significantly enhanced Firmicutes growth from day 2 to 28 and also increased Bacteroides abundance from day 28 to 42 in rumen and feces (P < 0.05). SB also significantly inhibited Proteobacteria abundance in rumen and feces during the study period (P < 0.05). SB also promoted some potential beneficial bacterial abundance, including Prevotella, Lachnospiraceae, Clostridium, Ruminococcus, and Muribaculaceae (P < 0.05). Additionally, Escherichia-Shigella abundance at SB0 was significantly lower than in the other groups (P < 0.05). In conclusion, this study firstly reported a dynamic curve showing of the SB effects on bacteria in calves before weaning. This study provides valuable evidence for the development of the gastrointestinal tract of the calves in the early stage of the life. SB supplementation improved the gastrointestinal health by regulating the bacterial populations. KEY POINTS: • The gastrointestinal tract of calves has been improved after the SB supplementation. • Microbes were the vital influential factor in the development of calves. • Intervention before weaning is an effective strategy for calf health.

Effects of dietary supplementation with multispecies probiotics on intestinal epithelial development and growth performance of neonatal calves challenged with Escherichia coli K99

BACKGROUND

Probiotics exhibit antibiotic properties and are capable of treating certain bacterial infections, including diarrhea. Therefore, the aim of this study is to investigate the effects of dietary supplementation with multispecies probiotic (MSP) on diarrhea, average daily gain (ADG) and intestinal development of neonatal calves challenged with Escherichia coli K99.

RESULTS

Thirty-six neonatal Holstein calves were randomly assigned to three treatment groups. After E. coli K99 challenge, calves in the control (C) and MSP treatment groups had significantly higher ADG and feed efficiency, and significantly lower fecal scores than those of calves in the diarrhea (D) group. The mean time of diarrhea resolution was 4.5 and 3.1 days for calves in the D and MSP treatment groups, respectively. Furthermore, the structures of the various segments (duodenum, jejunum and ileum) of the small intestine of the calves, activities of several small intestinal enzymes, and expression of several energy metabolism-related genes in the small intestine segments were significantly affected by MSP treatments.

CONCLUSION

Dietary supplementation of MSP had a positive effect in treating calf diarrhea; it improved ADG and feed efficiency and promoted development of the small intestine. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Bacteriophage EK99P-1 alleviates enterotoxigenic Escherichia coli K99-induced barrier dysfunction and inflammation

Bacteriophages, simply phages, have long been used as a potential alternative to antibiotics for livestock due to their ability to specifically kill enterotoxigenic Escherichia coli (ETEC), which is a major cause of diarrhea in piglets. However, the control of ETEC infection by phages within intestinal epithelial cells, and their relationship with host immune responses, remain poorly understood. In this study, we evaluated the effect of phage EK99P-1 against ETEC K99-infected porcine intestinal epithelial cell line (IPEC-J2). Phage EK99P-1 prevented ETEC K99-induced barrier disruption by attenuating the increased permeability mediated by the loss of tight junction proteins such as zonula occludens-1 (ZO-1), occludin, and claudin-3. ETEC K99-induced inflammatory responses, such as interleukin (IL)-8 secretion, were decreased by treatment with phage EK99P-1. We used a IPEC-J2/peripheral blood mononuclear cell (PBMC) transwell co-culture system to investigate whether the modulation of barrier disruption and chemokine secretion by phage EK99P-1 in ETEC K99-infected IPEC-J2 would influence immune cells at the site of basolateral. The results showed that phage EK99P-1 reduced the mRNA expression of ETEC K99-induced pro-inflammatory cytokines, IL-1β and IL-8, from PBMC collected on the basolateral side. Together, these results suggest that phage EK99P-1 prevented ETEC K99-induced barrier dysfunction in IPEC-J2 and alleviated inflammation caused by ETEC K99 infection. Reinforcement of the intestinal barrier, such as regulation of permeability and cytokines, by phage EK99P-1 also modulates the immune cell inflammatory response.

Seasonal and Age-Associated Pathogen Distribution in Newborn Calves with Diarrhea Admitted to ICU

Calf mortality constitutes a substantial loss for agriculture economy-based countries and is also a significant herd problem in developed countries. However, the occurrence and frequency of responsible gastro-intestinal (GI) pathogens in severe newborn diarrhea is still not well known. We aimed to determine the seasonal and age-associated pathogen distribution of severe diarrhea in newborn calves admitted to the intensive care unit (ICU) of Erciyes University animal hospital over a year. Fecal samples were collected during the ICU admissions, and specimens were subjected to a diarrheal pathogen screening panel that included bovine coronavirus (BCoV), Cryptosporidium spp., ETEC K99+, and bovine rotavirus, using RT-PCR and conventional PCR methods. Further isolation experiments were performed with permissive cell cultures and bacterial enrichment methods to identify the clinical importance of infectious pathogen shedding in the ICU. Among the hospitalized calves aged less than 45 days old, the majority of calves originated from small farms (85.9%). The pathogen that most frequently occurred was Cryptosporidium spp. (61.5%) followed by rotavirus (56.4%). The frequency of animal admission to ICU and GI pathogen identification was higher during the winter season (44.9%) when compared to other seasons. Most calves included in the study were 1-6 days old (44.9%). Lastly, co-infection with rotavirus and Cryptosporidium spp. occurred more frequently than other dual or multi-infection events. This study was the first to define severe diarrhea-causing GI pathogens from ICU admitted newborn calves in Turkey.

Isolation and Molecular Characterization of Enterotoxigenic Escherichia coli (ETEC) Strains From Industrial Dairy Farms of Hamedan, Iran

Background: Enterotoxigenic Escherichia coli (ETEC) is considered as one of the most common causes of infectious diarrhea in calves, infecting animals during the first week of age. The secretory diarrhea is attributed to the virulence factors of ETEC strains mainly including heat stable toxin (STa), as well as F5 (K99) and F41 fimbriae. Objectives: The present study was undertaken to investigate ETEC infection in neonatal calves of industrial dairy farms of Hamedan, Iran. Additionally, it was undertaken to investigate the genotypic screening of virulence genes in enterotoxigenic E. coli isolated from from dairy farms calves of Hamedan county. Materials and Methods: A total of 120 rectal swab samples were collected from healthy and diarrheic calves at one week of age belonging to eight farms. Conventional bacteriological methods, multiplex PCR, and antibiotic susceptibility test of the ETEC isolates were performed. Results: Nine E. coli isolates were found to be ETEC strains, carrying STa enterotoxin along with F5 and/or F41 fimbriae as the indicators of ETEC cells. Additionally, antibiotic susceptibility test of the ETEC isolates revealed that all of them were sensitive to trimethoprim-sulfamethoxazole, ciprofloxacin, and enrofloxacin, whereas complete resistance was observed against amoxicillin-clavulanic acid (100%) and polymyxin B (100%). The present study, conducted for the first time in Hamedan, indicated a prevalence of 7.5% for Enterotoxigenic Escherichia coli in the examined animals. Conclusion: Regarding economic losses of the infection in claves as well as the zoonotic nature of ETEC cells, it is recommended that measures should be taken, such as immunization of pregnant cows prior to the delivery, feeding of adequate colostrum to newborn calves at the right time, and adherence to hygiene practices on the farms to prevent and/or reduce the incidence of diarrhea cases caused by infection with these bacteria.

Combined effect of probiotics and specific immunoglobulin Y directed against Escherichia coli on growth performance, diarrhea incidence, and immune system in calves

Enterotoxigenic Escherichia coli (ETEC) K99 is one of the major pathogens associated with calf diarrhea. The induction of passive immunity in animals by immunoglobulin Y and using probiotics are inexpensive alternatives to antibiotics for the prevention and treatment of a number of bacterial infections, including diarrhea. Hence, the aim of this research was to evaluate the impact of dietary probiotics and ETEC K99-specific egg yolk antibody supplements, alone and in combination with each other, on health and growth parameters, diarrhea incidence and immune stimulation in newborn Holstein calves. One hundred and twenty neonatal calves were allocated randomly into 4 dietary groups (n = 30 per group) received colostrum/milk without any additives (control group), or supplemented with egg yolk powder contained E. coli K99-specific antibody (Ab group; 1 g/day), a commercial probiotic, Hypro-calves (Pro group; 3 g/day), and their combination (Ab+Pro group), from day (d) 1 to d28 of age. Analyses of the growth parameters, feed efficiency, fecal score, and microbiota and immune function were carried out on d0, 14, 21, and 28 of the experiment. Calves in Ab or Ab+Pro group had higher (P < 0.05) average daily gain compared to control and Pro groups during 0-14d. Feed efficiency of calves in Ab and Ab+Pro groups was significantly higher than that in control group during the period of 0-14d; however, no significant differences were observed in 0-28d period. Diarrhea prevalence and fecal score in Ab+Pro group were lower than control group (P < 0.05). Calves in Ab+Pro group had the lowest number of fecal E. coli in comparison to other groups on d28 (P < 0.05). Feeding Ab+Pro supplement increased (P < 0.05) concentrations of blood IgA and serum CD4 compared to the control group. Likewise, calves in Pro group had higher CD4 levels as compared to the control calves (P < 0.05). Serum concentration of interferon-gamma in control group was lower than other groups (P < 0.05). Overall, these data suggest that feeding a combination of probiotic and specific antibody against ETEC to neonate Holstein calves enhances feed efficiency, boosts immunity, and reduces diarrhea prevalence.

Phenotypic and genotypic characterization of enterotoxigenic Escherichia coli isolated from diarrheic calves in Argentina

Enterotoxigenic Escherichia coli (ETEC) is the most common and global cause of neonatal calf diarrhea, but there is a little information regarding calf ETEC strains in Argentina. In this study, five ETEC isolates from diarrheic dairy calves (2–10 d old) from Buenos Aires and Cordoba, Argentina were characterized on the basis of virulence gene (VG) pattern, O:H serotyping, hemolytic phenotype, phylogenetic group affiliation, antimicrobial (AM) resistance profile, and presence of integron class 1 and 2. The five isolates were examined by polymerase chain reaction (PCR) for the presence of 18 bovine VGs and showed the following genotypes: F5⁺/F41⁺/sta⁺ (D242), F5⁺/sta⁺ (D158), F5⁺/sta⁺ (D157), F5⁺ (D151-9), and F5⁺/iucD⁺ (D151-5). These VGs confer pathogenic potential and most of them are associated with the ETEC pathotype. The five isolates showed a non-hemolytic phenotype, belonged to five different serotypes: O101:H⁻, O141:H⁻, O60:H⁻, ONT:H10, and ONT:H⁻, and were assigned to the phylogenetic group A by the quadruplex Clermont PCR method. The AM resistance of the three isolates D242, D157, and D151-5 was determined by agar disk diffusion method for 24 AMs and they exhibited a multi-resistance phenotype (resistance to four different AM classes: Cephalosporins, Penicillins, Macrolides, and Ansamycins). In addition, class 1 integrons were found in the isolate D151-5 containing the dfrA17-aadA5 gene cassette and in the bovine ETEC reference strain FV10191 containing the dfrA1-aadA1 gene cassette. The present study revealed for the first time the occurrence of multi-resistant ETEC associated with neonatal diarrhea in dairy calves in Argentina. This finding may be used for diagnostic and therapeutic purposes.

Molecular analysis of Shiga toxin-producing Escherichia coli O157:H7 and non-O157 strains isolated from calves

Shiga toxin-producing Escherichia coli (STEC) O157 and non-O157 are food-borne pathogens and contaminants of foods of animal origin. This study was conducted to investigate the presence of virulence and integrase genes in STEC isolates from diarrhoeic calves in Fars Province, Iran. Five hundred and forty diarrheic neonatal calves were randomly selected for sampling. Rectal swabs were collected and cultured for isolation and identification of E. coli following standard methods. The isolates were analysed for the presence of class 1 integrons and bacterial virulence factors using polymerase chain reaction (PCR). Antimicrobial susceptibility testing was performed using the Kirby-Bauer disc diffusion method. Out of 540 diarrhoeic faecal samples, 312 (57.7%) harboured E. coli and 71 (22.7%) of them were identified as STEC: 41(69.5%) carried the stx2 gene, 21 (35.6%) carried the stx1 gene and 3 (5%) carried both. Twenty-six (44%) of the isolates showed the eaegene. Among the STEC isolates examined for susceptibility to eight antimicrobial agents, erythromycin and penicillin (96.8%) resistance were most commonly observed, followed by resistances to ampicillin (71.8%), tetracycline (62.5%) and trimethoprim/sulfamethoxazole (39%). Integrons were detected by PCR in 36% of the STEC tested isolates, 57 (89%) of which showed resistance to at least three antimicrobial agents. Our findings should raise awareness about antibiotic resistance in diarrhoeic calves in Fars Province, Iran. Class 1 integrons facilitate the emergence and dissemination of multidrug-resistance (MDR) among STEC strains recovered from food animals.

Effects of dietary supplementation with two alternatives to antibiotics on intestinal microbiota of preweaned calves challenged with Escherichia coli K99

The aim of this study was to investigate the effects of dietary supplementation with two alternatives to antibiotics (Candida tropicalis and mulberry leaf flavonoids) on intestinal microbiota of preweaned calves challenged with Escherichia coli K99. Sixty Holstein calves were randomly assigned to 5 treatments: fed a basal diet (N-CON); fed a basal diet and challenged with E.coli K99 (P-CON); fed a basal diet supplemented with C.tropicalis (CT), mulberry leaf flavonoids (MLF), and the combination of the two additives (CM), respectively, and challenged with E.coli K99. The MLF and CM groups had significantly higher average daily grain and feed efficiency, and significantly lower fecal scores compared with the P-CON group after E. coli K99 challenge. The supplementation groups increased the relative abundance, at the phylum level, of Bacteroidetes and Proteobacteria, whereas at the genus level, they increased the relative abundance of Prevotella, Lactobacillus, and Enterococcus. Quantitative PCR revealed that the CT, MLF, and CM groups had significantly lower copy numbers of E.coli K99 compared with the P-CON group. The CT, MLF, and CM treatments reduce days of diarrhea, improve intestinal health, and beneficially manipulate the intestinal microbiota in preweaned calves.

Genotypic analysis of virulence genes and antimicrobial profile of diarrheagenic Escherichia coli isolated from diseased lambs in Iran

The aim of the present study was to determine the analysis of virulence genes and antimicrobial profile of diarrheagenic Escherichia coli isolated from diseased lambs. Two hundred ninety E. coli isolates were recovered from 300 rectal swabs of diarrheic lambs and were confirmed by biochemical tests. The pathotype determination was done according to the presence of genes including f5, f41, LTI, STI, bfp, ipaH, stx 1 , stx 2 , eae, ehlyA, cnf 1 , cnf 2 , cdIII, cdIV, and f17 by PCR method. Sixty-six isolates (23.72%) possessed the STI gene and categorized into entrotoxigenic E. coli (ETEC). Nine isolates (3.1%) and five isolates (1.72%) were positive for the cnf1 and cnf2 genes which categorized into necrotoxic E. coli (NTEC). Hundred and seventeen isolates (40.34%) harbored stx 1 and/or stx 2 and classified as Shiga toxin-producing E. coli (STEC). Thirteen isolates (4.48%) were assigned to atypical entropathogenic E. coli (aEPEC) and possessed eae gene. Two isolates (0.68%) were positive for ipaH gene and were assigned to entroinvasive E. coli (EIEC). Statistical analysis showed a specific association between eae gene and STEC pathotype (P < 0.0001). The most prevalent resistance was observed against lincomycin (96.5%) and the lowest resistance was against kanamycine (56.02%), respectively. The high prevalence of STEC and ETEC indicates that diarrheic lambs represent an important reservoir for humans. ETEC may play an important role for frequent occurrence of diarrhea in lambs observed in this region. Due to high antibiotic resistance, appropriate control should be implemented in veterinary medicine to curb the development of novel resistant isolates.