Mastitis adversely affects milk production and in general cows do not regain their full production levels post recovery, leading to considerable economic losses. Moreover the percentage decrease in milk production depends on the specific pathogen that caused the infection and enterobacteria are responsible for this greater reduction. Phenotypic tests are among the currently available methods used worldwide to identify enterobacteria; however they tend to misdiagnose the species despite the multiple tests carried out. On the other hand The Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry (MALDI-TOF MS) technique has been attracting attention for its precise identification of several microorganisms at species level. In the current study, 183 enterobacteria were detected in milk (n = 47) and fecal samples (n = 94) from cows, and samples from water (n = 23) and milk lines (n = 19). All these samples were collected from a farm in Rio de Janeiro with the specific purpose of presenting the MALDI–TOF MS technique as an efficient methodology to identify Enterobacteriaceae from bovine environments. The MALDI–TOF MS technique results matched the biochemical test results in 92.9% (170/183) of the enterobacteria species and the gyrB sequencing confirmed 100% of the proteomic technique results. The amino acid decarboxylation test made the most misidentifications and Enterobacter spp. was the most misidentified genus (76.9%, 10/13). These results aim to clarify the current biochemical errors in enterobacteria identification, considering isolates from a bovine environment, and show the importance for more careful readings of phenotypic tests which are often used in veterinary microbiology laboratories.
The AmpC enzyme is normally expressed constitutively in Escherichia coli, and its overproduction confers resistance to cefoxitin. A newly reported AmpC, the extended-spectrum AmpC (ESAC), is related to resistance to cefepime, a fourth-generation cephalosporin. This enzyme presents more flexibility in the active site due to insertions, replacements, and deletions on AA sequences. Many isolates producing ESAC were reported in human clinical isolates, but E. coli ESAC producers were reported in animals only in France. The animal E. coli strains can produce this enzyme and possibly disseminate it to human and production environments. In our study, 3 strains of E. coli from milk and feces bovine samples, collected in Rio de Janeiro, Brazil, were suspected to produce ESAC. After excluding other mechanisms of resistance, the gene was sequenced to verify ESAC characteristics. These strains presented replacement of AA in omega and R2 loops, suggesting ESAC production. This is the first report to study ESAC E. coli in dairy farms in Brazil.
AmpC is a type of β-lactamase enzyme produced by bacteria; these enzymes are classified in Class C and Group 1, and these confer resistance to cephamycin. Enterobacterales producing AmpC are reported worldwide and have great clinical importance due to therapeutic restriction and epidemiological importance once the easy dissemination by plasmidic genes to other bacteria is a real threat. These genes are naturally found in some enterobacteria as Enterobacter cloacae, Morganella morganii, and Citrobacter freundii, but other species have demonstrated similar resistance phenotype of AmpC production. Genes carried in plasmids have been described in these species conferring resistance to cefoxitin and causing therapeutic failure in some bacterial infections. This work detected and described five clinical strains of Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae that presented plasmid ampC (pAmpC) isolated from the north of Portugal collected in 2009. AmpC production was confirmed by inhibition of the enzyme by cloxacillin and boronic acid in agar diffusion tests. Also, PCR (polymerase chain reaction) was performed for the detection of gene universal to AmpC, bla ampC , and others to AmpC group: bla ACC , bla CIT , bla CMY , bla DHA , and bla EBC. The conjugation in liquid medium for 24 h was realized to determine if gene is localized in chromosome or plasmid. The isolates and their conjugants showed phenotypic characteristics and bla CMY and bla CIT were detected by PCR corroborating the AmpC characteristics observed in these bacteria. Confirmation of transfer of plasmid containing genes encoding AmpC is of high epidemiological relevance to the hospital studied and demonstrated the importance of AmpC surveillance and studies in hospital and community environments in order to choose the appropriate therapy for bacterial infections.
The functionalization of nanoparticles with therapeutic peptides has been pointed out as a promising strategy to improve the applications of these molecules in the field of health sciences. Peptides are highly bioactive but face several limitations such as low bioavailability due to the difficulty of overcoming the physiological barriers in the body and their degradation by enzymes. In this work, gold nanoparticles (AuNPs) were co-functionalized with two therapeutic peptides simultaneously. The peptides from the complementary determining region of monoclonal antibodies, composed of the amino acid sequences YISCYNGATSYNQKFK (C7H2) and RASQSVSSYLA (HuAL1) were chosen for having exhibited antitumor and antimicrobial activity before. The peptides-conjugated AuNPs were characterized regarding size, morphology, and metal concentration by using TEM, dynamic light scattering, and ICP-OES techniques. Then, peptides-conjugated AuNPs were evaluated regarding the antimicrobial activity against E. coli, P. aeruginosa, and C. albicans. The antitumoral activity was evaluated in vitro by cell viability assays with metastatic melanoma cell line (B16F10-Nex2) and the cytotoxicity was evaluated against human foreskin fibroblast (Hs68) cell line. Finally, in vivo assays were performed by using a syngeneic animal model of metastatic melanoma. Our findings have highlighted the potential application of the dual-peptide AuNPs in order to enhance the antitumor and antimicrobial activity of peptides.
The objective of this work was to evaluate the influence of poultry litter reuse on the condemnation of chicken carcasses in two slaughterhouses under federal inspection in the State of São Paulo, which obtain poultry from farms with different bed reuse protocols. Brazil is a major producer and exporter of chicken meat and there are many losses in the production chain, which could result in higher productivity if there are not problems in that process. The management of poultry litter is important for the final quality of the carcasses and is associated with most of the pathologies found in broilers, such as colibacillosis. Do not observed condemnation by colibacillosis in the slaughtering "A" that farms reuse the chicken litter for a maximum of six times. But in the slaughterhouse "B" the carcasses rejection was 0.06% and the chickens were coming from farms that reuse the material for more than six times. Both farms reuse the chicken litter after turning and fermentation protocols. These results demonstrate a relation between the number of times the material is used and the pathology studied. Thus, the management of chicken litter can be responsible for the losses of carcasses by colibacillosis in the poultry industry.
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