There is an urgent need to control necrotic enteritis (NE) caused by Clostridium perfringens in chickens when antibiotics are withdrawn from feed. Carvacrol has strong antimicrobial activity and its ...delivery to the animal intestine can be significantly enhanced after encapsulation. The present study has investigated the potential of encapsulated carvacrol in controlling NE. In general, micro-encapsulation of carvacrol in an alginate-whey protein matrix showed no adverse effect on its antimicrobial activity towards C. perfringens in either Brain Heart Infusion (BHI) broth or a simulated gastrointestinal model. The minimum inhibitory concentrations of both encapsulated and un-encapsulated carvacrol were approximately 200 μl/l against C. perfringens in BHI. In a broiler infection model with C. perfringens, the diets supplemented with encapsulated carvacrol at the dose of either 250 or 650 μg/g significantly reduced NE in the chicken intestine, which was close to the degree of lesions observed in bacitracin/salinomycin treated birds. Supplementation with either bacitracin/salinomycin or encapsulated carvacrol showed no significant impact on intestinal burden of Lactobacillus. However, the treatment with bacitracin/salinomycin or the low dose of encapsulated carvacrol reduced the level of C. perfringens in the ileum of birds at 35 days of age. These results suggest that our encapsulated carvacrol can be used to combat NE disease in chickens.
With the noticed steady increase of global demand for animal proteins coupled with the current farming practices falling short in fulfilling the requested quantities, more attention is being paid for ...means and methods intended to maximize every available agricultural-resource in a highly sustainable fashion to address the above growing gap between production and consumers' demand. Within this regard, considerable efforts are being invested either in identifying new animal feed ingredients or maximizing the utilization of already established ones. The public preference and awareness of the importance of using waste products generated by fruit-dependent industries (juice, jams, spirits, etc.) has improved substantially in recent years where a genuine interest of using the above waste(s) in meaningful applications is solidifying and optimization-efforts are being pursued diligently. While many of the earlier reported usages of fruit pomaces as feedstuffs suggested the possibility of using minimally processed raw materials alone, the availability of exogenous digestive and bio-conversion enzymes is promising to take such applications to new un-matched levels. This review will discuss some efforts and practices using exogenous enzymes to enhance fruit pomaces quality as feed components as well as their nutrients' accessibility for poultry and swine production purposes. The review will also highlight efforts deployed to adopt numerous naturally derived and environmentally friendly catalytic agents for sustainable future feed applications and animal farming-practices.
Staphylococcus aureus is a leading cause of intramammary infections (IMI) and bovine mastitis is an important disease for the dairy industry. As this bacterium probably expresses specific genes for ...establishment of IMI, we studied the transcriptional profile of four S. aureus strains recovered from experimentally infected cows. Microbial RNA was extracted from bacteria isolated from milk, reverse-transcribed and labeled for hybridization to sub-genomic microarrays to detect candidate genes for further investigations. Several S. aureus genes were expressed during IMI; some were detected in samples from more than one strain, more than one cow and at more than one time point during infection. A selection of four genes showing strong expression and with putative functions in pathogenesis was further studied by qPCR. By comparing the expression in different media in vitro, we found that gene SACOL2171 was induced by iron restriction whereas the expression of the transcriptional regulator SACOL2325 and the ABC transporter SACOL0718-720 (vraFG) were induced by milk. In addition, the putative exotoxin SACOL0442 seemed to require the intramammary environment for expression. Gene-disrupted mutants for SACOL0720 and SACOL0442 showed no growth defect in vitro but were attenuated during bovine IMI, causing infections with significant reductions in bacterial and somatic cell counts. The milk from the mammary quarters infected with these mutants also showed better appearance and composition than milk from quarters infected with the wild type. In conclusion, we have identified genes that are most likely important for S. aureus IMI. These represent novel candidates to include in a vaccine.
Staphylococcus aureus is an important pathogen that is responsible for a wide range of infections, including bovine mastitis. Previously, 54 genes from
S. aureus that were up-regulated in an ...iron-restricted medium and in mice were identified. Seven of those genes were selected from five iron-acquisition systems (isd, feo, sir, sst, and fhu), and the proteins were evaluated as potential vaccine targets to prevent bovine mastitis. The antigenicity of the recombinant proteins obtained with each studied gene was evaluated in rabbits and/or cattle. Immune sera were used to test the bacterial accessibility of the native proteins. All the proteins were immunogenic in rabbits or cattle. IsdH, IsdB, FeoB and SstD were expressed on the bacterial surface, with IsdB and IsdH more expressed in an iron-restricted environment. The capacity of antibodies to prevent infection was measured in a mouse mastitis model. Preincubation of
S. aureus with serum against IsdH or with the pool of sera against IsdB, SstD and FeoB led to decreased colonization of the mouse mammary glands. Lastly, cattle immunization with IsdH induced a strong and long-lasting immune response with IgG2 production. The protein IsdH appears to be a good vaccine candidate to prevent
S. aureus bovine mastitis.
Extraintestinal pathogenic
Escherichia coli
(ExPEC) includes several serotypes that have been associated with colibacillosis in poultry, as well as urinary tract infections and newborn meningitis in ...humans. This study investigated the antimicrobial activities of ceftriaxone (AXO) and cranberry pomace extracts (CRAN) alone or in combination (CC) against multidrug-resistant (MDR) ExPEC from broiler. The growth-inhibitory activity of CRAN and synergy tests by a checkerboard method were determined in cation-adjusted Mueller–Hinton broth (CAMHB). The transcriptomic profile of the MDR
E. coli
O7:H18 (ST38) grown in CAMHB supplemented with sub-inhibitory concertation of CRAN and AXO alone or in combination was obtained by RNA-seq. The MIC of CRAN for all isolates was 16 mg/mL. An additive activity was observed between 4 mg/mL of CRAN and 4 μg/mL of AXO. Compared to the control, the transcriptomic analysis revealed that 4 mg/ml of (1/4MIC) CRAN and its combination with 4 μg/mL of (1/8MIC) AXO (CC) exposures resulted in 727 and 712 differentially expressed genes, respectively (false discovery rate < 0.001 and log
2
-fold change > 2), in the studied
E. coli
. Major virulence genes including adhesins (
fim, flg, csg
, and
yad
), protectins (
omp, tra, waa
, and
hly
), secretion systems (
hof, pho
, and
vir
), and quorum sensing (
lsr
), which are energetically expensive for bacteria, were downregulated. Most importantly, 1/4MIC of CRAN or CC downregulated the β-lactamase
bla
CMY-2
and efflux pump including
tolC, mdtEIJ, gadEW
, and their regulator gene
evgS
, while upregulating the cysteine biosynthesis and oxidative stress-related regulatory genes including
cys, dmlA, sbp, nrdGHI, soxSR
, and
rpoH
. Downregulation of multiple enzymes involved in TCA cycles and upregulation of Fe–S cluster coordinated by Cys and Isc proteins reflect the regulation of energy metabolism of the studied
E. coli
upon CRAN or CC exposure. The downregulation of outer membrane protein genes that control permeability barriers, along with different antimicrobial resistance genes, demonstrates that CRAN may have the unique potential to enhance the antimicrobial activities of third-generation cephalosporins such as AXO against MDR
E. coli
.
The goal of this study was to assess the distribution of antimicrobial resistance (AMR) genes in Escherichia coli isolates recovered from a commercial beef processing plant. A total of 123 ...antimicrobial-resistant E. coli isolates were used: 34 from animal hides, 10 from washed carcasses, 27 from conveyers for moving carcasses and meat, 26 from beef trimmings, and 26 from ground meat. The AMR genes for β-lactamase (bla(CMY), bla(SHV), and bla(TEM)), tetracycline (tet(A), tet(B), and tet(C)), sulfonamides (sul1, sul2, and sul3), and aminoglycoside (strA and strB) were detected by PCR assay. The distribution of tet(B), tet(C), sul1, bla(TEM), strA, and strB genes was significantly different among sample sources. E. coli isolates positive for the tet(B) gene and for both strA and strB genes together were significantly associated with hide, washed carcass, and ground meat samples, whereas sul1 gene was associated with washed carcass and beef trimming samples. The bla(TEM) gene was significantly associated with ground meat samples. About 50% of tetracycline-resistant E. coli isolates were positive for tet(A) (14%), tet(B) (15%), or tet(C) (21%) genes or both tet(B) and tet(C) genes together (3%). The sul2 gene or both sul1 and sul2 genes were found in 23% of sulfisoxazole-resistant E. coli isolates, whereas the sul3 gene was not found in any of the E. coli isolates tested. The majority of streptomycin-resistant E. coli isolates (76%) were positive for the strA and strB genes together. The bla(CMY), bla(TEM), and bla(SHV) genes were found in 12, 56, and 4%, respectively, of ampicillin-resistant E. coli isolates. These data suggest that E. coli isolates harboring AMR genes are widely distributed in meat processing environments and can create a pool of transferable resistance genes for pathogens. The results of this study underscore the need for effective hygienic and sanitation procedures in meat plants to reduce the risks of contamination with antimicrobial-resistant bacteria.
The objective of this study was to investigate the distribution and persistence of antimicrobial resistance genotypes of enterococci from broilers fed bambermycin (BAM), penicillin (PEN), salinomycin ...(SAL), bacitracin (BAC), or a salinomycin/bacitracin combination (SALBAC) for 35 days. A total of 95 enterococci from cloacal (n = 40), cecal (n = 38), and litter samples collected on day 36 (n = 17) were isolated weekly from day 7 to 36. All isolates were identified by API-20 Strep and their antimicrobial susceptibilities were evaluated using the Sensititre system with the plates for Gram positive bacteria. Whole genome sequencing (WGS) was used to assess their intra- and inter-genetic variability, with a focus on virulence and antibiotic resistance characteristics. All isolates were further characterized for hemolysin production (HEM), bile salt hydrolysis (BSH), and gelatinase (GEL) activities. Of the 95 isolates, Enterococcus faecium (n = 58) and Enterococcus faecalis (n = 24) were the most common Enterococcus species identified. Significant differences in the level of resistance for the E. faecium isolates to ciprofloxacin, macrolide, penicillin and tetracycline were observed among treatments. The bcrR, mefA, and aac(6) genes were higher in BAM treatment than the other groups whereas bcrR, ermA, ermB, aphA(3), and tetL were more prevalent in PEN and BAC treatments. Overall, E. faecium isolates showed a higher prevalence of antimicrobial resistance, but E. faecalis from litter also exhibited a significant level of resistance. A range of 4–15 different virulence genes was detected in E. faecalis. All isolates from litter but one (94.1%) showed BSH activities while 52.9% of them produced GEL. HEM activity was observed only in isolates collected on Day 7 (n = 9) and Day 14 (n = 1). This study confirmed that genetically diverse AMR enterococci harboring virulence factors can be promoted by the use of certain antimicrobials in feed. Such enterococci could persist in broiler chickens and their litter, which can potentially contaminate the soil upon land application.
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