We have recently demonstrated that an attenuated strain of Salmonella enterica serovar Typhimurium unable to synthesize the zinc transporter ZnuABC (S. Typhimurium ΔznuABC), is able to protect mice against systemic and enteric salmonellosis and is safe in pigs. Here, we have tested the protective effects of S. Typhimurium ΔznuABC in pigs. Resistance to challenge with the fully virulent strain S. Typhimurium ATCC 14028 was assessed in animals vaccinated with S. Typhimurium ΔznuABC (two dosages tested), in controls vaccinated with a formalin-inactivated virulent strain and in unvaccinated controls. Clinical signs of salmonellosis, faecal shedding and bacterial colonization of organs were used to assess vaccine-induced protection. After the challenge, pigs vaccinated with the attenuated S. Typhimurium ΔznuABC strain did not display clinical signs of salmonellosis (fever or diarrhoea). The vaccine also reduced intestinal tract colonization and faecal shedding of the fully virulent Salmonella strain, as compared to control groups. S. Typhimurium ΔznuABC represents a promising candidate vaccine against salmonellosis in pigs.
Objective:
The objectives of this study were to determine the biofilm-forming capability and antimicrobial susceptibility of
Escherichia coli
recovered from bovine endometritis samples.
Materials and Methods:
A total of 120 uterine specimens were collected from cows suffering from endometritis for bacteriological examination. Antimicrobial susceptibility testing was carried out for all isolated
E. coli
by using the disc diffusion method. The isolates were phenotypically studied for biofilm-forming ability by cultivation on yeast extract -casamino acids Congo red agar (CRA). Some randomly selected isolates were chosen for the molecular identification of some virulence and resistance genes.
Results:
A total of 58(48.3%)
E. coli
isolates could be isolated from the 120 samples. Antimicrobial susceptibility testing exhibited that 91.4%, 79.3%, 79.3%, 74.1%, and 58.6% of the isolates were sensitive to gentamicin, amoxicillin-clavulanic acid, ciprofloxacin, cephalexin, and sulfamethoxazole- trimethoprim, respectively. On the other hand, 91.4% and 70.7% isolates were resistant to cefotaxime and doxycycline, respectively. Cultivation on CRA revealed that 46.6% of isolates were biofilm producers. The molecular detection of resistance and virulence genes declared that all isolates harbored
bla
TEM
,
sul
1,
tet
A,
qnr
S, bla
CTX-M
, and
fim
H with a percentage of 100%,
pap
C (40%), and
hly
A (10%).
Fim
H was the most prevalent biofilm-associated gene.
Conclusion:
The present study highlights the high prevalence of multi-drug- resistant
E. coli
associated with bovine endometritis. The detection of the
fim
H gene is circumstantial evidenced that this gene has a crucial role in biofilm formation in intrauterine pathogenic
E. coli
.
Salmonellosis is a major problem for the poultry industry, and this problem represents a critical food safety hazard. Resistance to antimicrobial agents within nontyphoidal Salmonellae is a serious problem. The present study aimed to analyze genetically some β-lactamase resistance genes and some virulence associated genes in Salmonella isolates from broiler chicken. Five hundred samples were collected from diseased broiler chickens of different ages (3-6 weeks) from different farms in Assiut Governorate in Egypt during the period from January 2015 to December 2015. Bacteriological examination showed that 26 Salmonella isolates were recovered with a prevalence rate of 5.2% Serotyping of Salmonella isolates showed that S. Enteritidis S. Typhimurium, and S. Kentuky were identified at rates of 50%, 30.8% and 19.2%, respectively. Results of antibiogram showed that 18 Salmonella isolates (92.3%) were multidrug resistant. All isolates were screened for the presence of 2 β-lactamase resistance genes (blaCTX and blaCMY) as well as 3 virulence genes (stn, invA and hilA) using multiplex PCR. The overall prevalences were 53.9% for blaCTX and 34.6% for blaCMY. Meanwhile, stn, invA and hilA genes were found in 96.2%, 100% and 84.7% of isolates, respectively.
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