Browsing by Issue Date, starting with "2016-05-23"
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- In Vitro Activity of Quaternary Ammonium Surfactants against Streptococcal, Chlamydial, and Gonococcal Infective AgentsPublication . Inácio, Ângela S.; Nunes, Alexandra; Milho, Catarina; Mota, Luís Jaime; Borrego, Maria J.; Gomes, João P.; Vaz, Winchil L.C.; Vieira, Otília V.Quaternary ammonium compounds (QAC) are widely used, cheap, and chemically stable disinfectants and topical antiseptics with wide-spectrum antimicrobial activities. Within this group of compounds, we recently showed that there are significant differences between the pharmacodynamics of n-alkyl quaternary ammonium surfactants (QAS) with a short (C12) alkyl chain when in vitro toxicities toward bacterial and mammalian epithelial cells are compared. These differences result in an attractive therapeutic window that justifies studying short-chain QAS as prophylactics for sexually transmitted infections (STI) and perinatal vertically transmitted urogenital infections (UGI). We have evaluated the antimicrobial activities of short-chain (C12) n-alkyl QAS against several STI and UGI pathogens as well as against commensal Lactobacillus species. Inhibition of infection of HeLa cells by Neisseria gonorrhoeae and Chlamydia trachomatis was studied at concentrations that were not toxic to the HeLa cells. We show that the pathogenic bacteria are much more susceptible to QAS toxic effects than the commensal vaginal flora and that QAS significantly attenuate the infectivity of N. gonorrhoeae and C. trachomatis without affecting the viability of epithelial cells of the vaginal mucosa. N-Dodecylpyridinium bromide (C12PB) was found to be the most effective QAS. Our results strongly suggest that short-chain (C12) n-alkyl pyridinium bromides and structurally similar compounds are promising microbicide candidates for topical application in the prophylaxis of STI and perinatal vertical transmission of UGI.
- Minutes of the sand meeting during the USEPA beach conference 2016Publication . Brandão, João; Whitman, Richard; Solo-Gabriele, Helena MIntroduction to the document: Before the US EPA Recreational Beaches Conference of April 2016 in New Orleans there was a series of email exchanges in beachnet; comparing the sand/microbe hydrodynamics of difference regions of the world and their influence on fecal indicator bacteria levels. As a follow-up of the mail exchange, a live meeting took place during the conference, divided in an introductory meeting (13th April) and a general discussion meeting (14th April). The Minutes of these meetings were joined together this document. Its first section corresponds to the general discussion meeting and the second to the introductory meeting. Abstract: The goal of the meeting was to draw upon researcher experiences from all regions around the world to develop a consensus conceptual model that would explain the impacts of sand dynamics on FIB levels in both sand and water. With this consensus model, statements could be made about the impacts of climate change on microbe levels at the water/sand interface. The meeting was structured with three presentations followed by a focus on developing two consensus statements: one focused on the influence of sand dynamics on FIB levels and another focused on climate change impacts. The three presentations at the beginning of the meeting were given by Kevan Yamahara, Alan Piggot and Laura Vogel. Consensus Statement #1: Hydrometerological trends impact sand dynamics. Consensus Statement #2: The geomorphological and hydrometerological conditions affect FIB dynamics in sands.
- QnrS1- and Aac(6')-Ib-cr-Producing Escherichia coli among Isolates from Animals of Different Sources: Susceptibility and Genomic CharacterizationPublication . Jones-Dias, Daniela; Manageiro, Vera; Graça, Rafael; Sampaio, Daniel A.; Albuquerque, Teresa; Themudo, Patrícia; Vieira, Luís; Ferreira, Eugénia; Clemente, Lurdes; Caniça, ManuelaSalmonella enterica and Escherichia coli can inhabit humans and animals from multiple origins. These bacteria are often associated with gastroenteritis in animals, being a frequent cause of resistant zoonotic infections. In fact, bacteria from animals can be transmitted to humans through the food chain and direct contact. In this study, we aimed to assess the antibiotic susceptibility of a collection of S. enterica and E. coli recovered from animals of different sources, performing a genomic comparison of the plasmid-mediated quinolone resistance (PMQR)-producing isolates detected. Antibiotic susceptibility testing revealed a high number of non-wild-type isolates for fluoroquinolones among S. enterica recovered from poultry isolates. In turn, the frequency of non-wild-type E. coli to nalidixic acid and ciprofloxacin was higher in food-producing animals than in companion or zoo animals. Globally, we detected two qnrS1 and two aac(6')-Ib-cr in E. coli isolates recovered from animals of different origins. The genomic characterization of QnrS1-producing E. coli showed high genomic similarity (O86:H12 and ST2297), although they have been recovered from a healthy turtle dove from a Zoo Park, and from a dog showing symptoms of infection. The qnrS1 gene was encoded in a IncN plasmid, also carrying bla TEM-1-containing Tn3. Isolates harboring aac(6')-Ib-cr were detected in two captive bottlenose dolphins, within a time span of two years. The additional antibiotic resistance genes of the two aac(6')-Ib-cr-positive isolates (bla OXA-1, bla TEM-1,bla CTX-M-15, catB3, aac(3)-IIa, and tetA) were enclosed in IncFIA plasmids that differed in a single transposase and 60 single nucleotide variants. The isolates could be assigned to the same genetic sublineage-ST131 fimH30-Rx (O25:H4), confirming clonal spread. PMQR-producing isolates were associated with symptomatic and asymptomatic hosts, which highlight the aptitude of E. coli to act as silent vehicles, allowing the accumulation of antibiotic resistance genes, mobile genetic elements and other relevant pathogenicity determinants. Continuous monitoring of health and sick animals toward the presence of PMQR should be strongly encouraged in order to restrain the clonal spread of these antibiotic resistant strains.