Molecular typing of Campylobacter jejuni strains: comparison among four different techniques.

This study compared the ability of pulsed-field gel electrophoresis (PFGE), flaA small variable region (SVR) sequencing, analysis of the clustered regularly interspaced short palindromic repeats locus by high resolution melting analysis (CRISPR-HRMA), and multilocus sequence typing (MLST) for typing 111 Campylobacter jejuni strains isolated from diverse sources during 20 years in Brazil. For this, we used previous results obtained by PFGE and flaA-SVR sequencing from our research group and performed CRISPR-HRMA and MLST typing for the first time. Furthermore, the discrimination index (DI) of each method was accessed. The DI for PFGE, flaA-SVR sequencing, CRISPR-HRMA, and MLST was 0.980, 0.932, 0.868, and 0.931, respectively. By PFGE and flaA-SVR sequencing, some strains from clinical and non-clinical sources and from humans and animals presented ≥ 80% similarity. Similarly, some strains from different origins presented the same ST and CRISPR-HRMA types. In conclusion, despite the different DI values, all assays provided the same epidemiological information suggesting that a potential transmission may have occurred between C. jejuni from clinical and non-clinical sources and from animals and humans in Brazil. Furthermore it was demonstrated the suitability of PFGE that should be used preferably together with MLST and/or flaA-SVR sequencing for typing C. jejuni strains.

Removal of contaminants of emerging concern (CECs) and antibiotic resistant bacteria in urban wastewater using UVA/TiO2/H2O2 photocatalysis.

The dispersion of pollutants and proliferation of antibiotic resistant bacteria in the aquatic environment are an emerging health concern worldwide. In this sense, it is essential to develop new technologies to increase the quality of wastewater treatment, which is spread throughout the environment. The present study has demonstrated evidence of the existence of antibiotic and mercury-resistant bacteria in the aquatic environment. The application of heterogeneous photocatalysis with UVA/TiO2 P25 slurry (200 mg L-1), UVA/TiO2-immobilized, and UVA/TiO2-immobilized/H2O2 were evaluated for the simultaneous elimination of a mixture of contaminants of emerging concern (acetamiprid (ACP), imazalil (IMZ) and bisphenol A (BPA)) and inactivation of antibiotic and mercury-resistant bacteria (Pseudomonas aeruginosa and Bacillus subtilis). UVA/TiO2-immobilized/H2O2 increased the inactivation and elimination of the contaminants. After the combined treatment, the mixture of BPA, IMZ and ACP decreased 62%, 21% and <5%, respectively, after 300 min at 13.10 kJ L-1 of accumulated UV energy. The Pseudomonas aeruginosa strain was inactivated after 120 min using 5.24 kJ L-1 of accumulated UV energy, whereas the Bacillus subtilis strain was shown to be extremely resistant, with a capacity to develop mechanisms to avoid the oxidation process.

Primary fecal culture used as template for PCR detection of diarrheagenic E. coli virulence factors.

The PCR technique applied to primary fecal cultures (PFC-PCR) was compared to the usual method employing isolated colonies (IC-PCR) in order to assess its sensitivity in the detection of virulence markers of diarrheagenic Escherichia coli in fecal samples obtained from children with diarrhea. Among the 149 samples analysed, PFC-PCR detected 81(54.4%) samples presenting one or two virulence markers, while IC-PCR detected only 59 (39.6%) positive samples. The markers detected in order of frequency were: pAA, LT-I, eaeA, ST-I, daaE, and ipaH. The PFC-PCR method of detection of diarrheagenic E. coli virulence markers proved to be reliable and more sensitive (p<0.05) than the usual method employing isolated colonies. It has also the advantage of being faster and less expensive than the detection methods in current use.