Antibiotic resistance in faecal bacteria (Escherichia coli, Enterococcus spp.) in feral pigeons

AIMS

To determine the presence of antibiotic-resistant faecal Escherichia coli and Enterococcus spp. in feral pigeons (Columba livia forma domestica) in the Czech Republic.

METHODS AND RESULTS

Cloacal swabs of feral pigeons collected in the city of Brno in 2006 were cultivated for antibiotic-resistant E. coli. Resistance genes, class 1 and 2 integrons, and gene cassettes were detected in resistant isolates by polymerase chain reaction (PCR). The samples were also cultivated for enterococci. Species status of enterococci isolates was determined using repetitive extragenic palindromic-PCR. Resistance genes were detected in resistant enterococci by PCR. E. coli isolates were found in 203 of 247 pigeon samples. Antibiotic resistance was recorded in three (1·5%, n(E. coli) =203) isolates. Using agar containing ciprofloxacin, 12 (5%, n(samples) =247) E. coli strains resistant to ciprofloxacin were isolated. No ESBL-producing E. coli isolates were detected. A total of 143 enterococci were isolated: Ent. faecalis (36 isolates), Ent. faecium (27), Ent. durans (19), Ent. hirae (17), Ent. mundtii (17), Ent. gallinarum (12), Ent. casseliflavus (12) and Ent. columbae (3). Resistance to one to four antibiotics was detected in 45 (31%) isolates. Resistances were determined by tetK, tetL, tetM, tetO, aac(6')aph(2''), ant(4')-Ia, aph(3')-IIIa, ermB, pbp5, vanA and vanC1 genes.

CONCLUSIONS

Antibiotic-resistant E. coli and Enterococcus spp. occurred in feral pigeons in various prevalences.

SIGNIFICANCE AND IMPACT OF THE STUDY

Feral pigeon should be considered a risk species for spreading in the environment antimicrobial resistant E. coli and enterococci.

Preoperative radiotherapy and concomitant capecitabine treatment induce thymidylate synthase and thymidine phosphorylase mRNAs in rectal carcinoma

This work is intended to study the effect of preoperative capecitabine and radiotherapy treatment on the levels of thymidylate synthase (TS), thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) mRNAs in rectal carcinoma. 55 patients with locally advanced rectal carcinoma (cT3-4, N0, M0 or cT2-4,N+, M0) were treated with capecitabine 825 mg/m2 twice a day and pelvic radiotherapy 1,8 Gy daily up to cumulative dose of 45 Gy, boosting up to 50,4 Gy. Patients underwent surgery 6th week after the completion of chemoradiotherapy. Biopsies of rectal carcinoma were taken before starting therapy and 14 days after its cesation. Biopsies were examined for TS, DPD and TP mRNA levels. CEA in serum was examined to monitor relapses. Both TP and TS mRNA increase two weeks after starting therapy (p<0,001). TP mRNA median levels were elevated 2,3x after starting therapy. Moreover responders exhibit 1,5x higher induction than non-responders both before and after starting therapy, but difference is significant before therapy only (p=0,017). Non-responders have most frequent TS induction. Complete remission was observed in 17% and substantial responses with microscopic residuum only in additional 19% of cases were achieved. The pathologic downstaging rate was 76%. Our data show that TS and TP mRNA are induced by preoperative chemoradiotherapy in both responders and nonresponders. TP induction is in accordance with the expected role of TP in the activation of capecitabine and the known promoting role of TP in tissue fibrosis frequently associated with tumor regression.

Expression of p53 and p53/47 are controlled by alternative mechanisms of messenger RNA translation initiation

P53 controls the growth and survival of cells by acting in response to a multitude of cellular stresses. It is, however, not yet fully understood how different p53 activation pathways result in either cell cycle arrest or apoptosis. We and others have described an N-terminally truncated p53 protein (p53/47) originating from a second translation initiation site in the p53 messenger RNA (mRNA), which can interact with p53 and impose altered stability and transactivation properties to p53 complexes. Here we show that cap-dependent and cap-independent mechanisms of initiation govern the translation of the p53 mRNA. Changes in synthesis of full-length p53 or p53/47 are regulated through distinct cell stress-induced pathways acting through separate regions of the p53 mRNA. We also show that some cytotoxic drugs require the presence of full-length p53 to induce apoptosis, whereas for others p53/47 is sufficient. This indicates that by harbouring alternative translation initiation sites, the p53 mRNA gives rise to different levels of the p53 isoforms which help to orchestrate the cell biological outcome of p53 activation in response to different types of cell stress. This sheds new light into the way p53 can integrate and differentiate a large multiplicity of changes in the cellular environment.