Residual concentrations of antimicrobial growth promoters in poultry litter favour plasmid conjugation among Escherichia coli

Considering that plasmid conjugation is a major driver for the dissemination of antimicrobial resistance in bacteria, this study aimed to investigate the effects of residual concentrations of antimicrobial growth promoters (AGPs) in poultry litter on the frequencies of IncFII-FIB plasmid conjugation among Escherichia coli organisms. A 2x5 factorial trial was performed in vitro, using two types of litter materials (sugarcane bagasse and wood shavings) and five treatments of litter: non-treated (CON), herbal alkaloid sanguinarine (SANG), and AGPs monensin (MON), lincomycin (LCM), and virginiamycin (VIR). E. coli H2332 and E. coli J62 were used as donor and recipient strains, respectively.The presence of residues of monensin, lincomycin and virginiamycin increased the frequency of plasmid conjugation among E. coli in both types of litter materials. On the contrary, sanguinarine significantly reduced the frequency of conjugation among E. coli in sugarcane bagasse litter. The conjugation frequencies were significantly higher in wood shavings compared to sugarcane bagasse only in the presence of AGPs. Considering that the presence of AGPs in the litter can increase the conjugation of IncFII-FIB plasmids carrying antimicrobial resistance genes, the real impact of this phenomenon on the dissemination of antimicrobial resistant bacteria in the poultry production chain must be investigated.

Enhancement of the antibiotic activity mediated by the essential oil of Ocotea odorifera (VELL) ROWHER and safrole association

In a recent study, our research group demonstrated that the essential oil of Ocotea odorifera (EOOO) and its major compound safrole potentiated the action fluoroquinolones, modulating bacterial resistance possibly due to direct inhibition of efflux pumps. Thus, in the present study, we investigated whether these treatments could enhance the activity of gentamicin and erythromycin against multidrug-resistant (MDR) bacteria. The EOOO was extracted by hydrodistillation, and the phytochemical analysis was performed by gas chromatography coupled to mass spectrometry (GC-MS). The antibiotic-enhancing effect of the EOOO and safrole against MDR strains of Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa was analyzed by the broth microdilution method. The chemical analysis confirmed the presence of safrole as a major component among the 16 compounds identified in the EOOO. Both the essential oil and the isolated compound showed clinically relevant antibacterial activities against S. aureus. Regarding the modulation of antibiotic resistance, the EOOO was found to enhance the activity of erythromycin against the strains of P. aeruginosa and S. aureus, as well as improving the action of gentamicin against S. aureus. On the other hand, safrole potentiated the activity of gentamicin against the S. aureus strain alone. It is concluded, therefore, that the EOOO and safrole can enhance the activity of macrolides and aminoglycosides, and as such are useful in the development of therapeutic tools to combat bacterial resistance against these classes of antibiotics.

E-cadherin immunoexpression patterns in the characterisation of gastric carcinoma histotypes

AIMS

E-cadherin, the main epithelial intercellular adhesion molecule, is abnormally expressed in many cancer types, including gastric carcinoma, which is the second leading cause of cancer death worldwide. The aim of this study was to contribute to the characterisation of gastric carcinoma histotypes based on a new approach to E-cadherin immunoexpression.

METHODS

97 gastric tumour samples obtained from the files of the Hospital of Cancer/Cancer Institute of Ceará, Brazil, were histologically analysed and classified as intestinal (n=40), diffuse (n=34), mixed (n=16) or unclassified (n=7) carcinomas. Immunohistochemistry was performed on the tissue microarray sections. Scores were applied according to the system of Jawhari: 0, no staining; 1, cytoplasmic staining; 2, cytoplasmic and membranous staining in the same case; 3, normal membranous immunoexpression; abnormal patterns: scores 0, 1 and 2; normal pattern: score 3. Jawhari scores were then evaluated utilising another approach: the absence of membranous expression scores (0 and 1) versus the presence of membranous expression (scores 2 and 3).

RESULTS

A significant association between membranous expression of E-cadherin and the intestinal histotype (36/40 (90%), and 28/41 (68%) for other histotypes) was found, while diffuse carcinomas were related to the absence of membranous expression. A very strong and peculiar relationship was observed between cytoplasm-exclusive E-cadherin expression (score 1) and the diffuse component of mixed tumours (11/16 (69%)).

CONCLUSIONS

E-cadherin immunoexpression patterns help us to characterise gastric carcinoma histotypes. The presence or absence of membranous staining is the most valuable criterion in evaluating E-cadherin expression. Mixed tumours show a characteristic E-cadherin cytoplasmic expression in gastric carcinomas.

Evaluation of molecular markers in hepatic metastasis of colorectal adenocarcinoma

BACKGROUND/AIMS

There were 49 patients studied, coming from The Liver Unit at the "Hospital das Clinicas da Faculdade de Medicina da USP (N=41) and from "Prof. Dr. Angelita Habr-Gama and Joaquim Gama-Rodrigues Surgery Institute", SP (N=8); all of which had hepatic metastasis of colorectal adenocarcinoma, with no evidence of concurrent metastasis in any other organs and were submitted to surgical treatment, during the period of 1992 to 2002, with the aim of analyzing the immunoexpression of the p53, ki-67, p16 and molecular markers in order to relate the disease-free period with the prognosis.

METHODOLOGY

The patient's clinical data were analyzed retrospectively for verification of information such as age, gender, size of the hepatic metastasis and/or the largest lesion, number of satellite nodules resected and compromised, margin of resection free from neoplasia.

RESULTS

The immunoexpression of the p53 was associated with the shortest period of life free from disease (p = 0.04). The proliferation marker ki-67 was not associated with the reduction of the disease-free interval and survival; the immunoexpression of the proliferation marker p16 was not associated with the reduction of disease-free period and survival, however, it was associated with hepatic metastasis synchronism. In patients who received postoperative systemic chemotherapy with 5-FU and leucovorin, the immunoexpression on the hepatic metastasis was not associated with a longer disease-free interval.

CONCLUSIONS

Molcular markers may be useful to evaluate hepatic metastasis of colorectal Adenocarcinoma.

Nonspecific genetic regulation of antibody responsiveness in the mouse

Four lines of mice were produced by selective breeding for quantitative agglutinin responsiveness to flagellar (f) or somatic (s) antigens (Ags) of Salmonellae: high (H) or low (L) responder lines to fAg and H and L responder lines to sAg. The Salmonellae contained both f and sAgs, the Ag used to perform the selection was the Selection Ag and the other was the Associated Ag. The selective breeding produced a progressive interline separation with an equivalent effect for both Ags. After 15 generations (F15) the level of agglutinin response was about 60 times higher in H than in L responders. About 50% of the phenotypic variation of the character investigated is determined by a group of immune response genes, the rest is due to environmental factors. The nonspecific effect of this group of immune response genes was investigated by measuring the responses to three independent antigens: Sheep erythrocytes (SE), dinitrophenyl-conjugated human IgG (DNP-HGG) and bovine IgG (BGG). The selection for fAg response produced an equivalent modification in the respnsiveness to the Associated Ag (97%) and to BGG (130%). This nonspecific effect was smaller for responsiveness to SE and DNP-HGG, 58% and 41% of the Selection Ag response, respectively. The selection for sAg response produced a nonspecific modification of responsiveness of 94% for the Associated Ag of 74% for BGG and 63% for DNP-HGG. An important exception concerned SE to which an equal antibody response is produced in high and low lines of sAg selection.