No abstract

We have developed a method for the detection of viruses in environmental samples that we have called enterophages, that specifically infect Enterococcus faecalis. This method has allowed us to determine the prevalence and to study the ecology of this group of phages. The enterophages replicate at 37 degrees C, and at 41 degrees C. The presence of NaN(3) in the media inhibits the growth of background microbiota and allows an accurate, specific and rapid detection of these viruses. Enterophages were present in raw domestic sewage at lower concentrations (average 1.8 x 10(2) PFU/100 mL) than those of coliphages (average 1.7 x 10(5) PFU/100 mL). Phages were characterised by transmission electron microscopy showing icosahedral capsids, some with non-contractile tails as well as icosahedral non-tailed capsids. Different isolates had capsid sizes ranging from 20 nm to about 75 nm in diameter. These data describe a new group of phages that may serve as alternate indicators of human faecal pollution, especially in recreational waters. The ecology of these enterophages indicates that these may be strictly of human origin.

We evaluated the antimicrobial activity and some mechanisms used by subinhibitory and inhibitory concentrations of the essential oil, obtained from leaves of Plectranthus amboinicus, against a standard strain of Klebsiella pneumoniae and 5 multiresistant clinical isolates of the bacteria. The minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), the rate of kill and the pH sensitivity of the essential oil were determined by microdilution tests performed in 96-well plates. Subinhibitory and inhibitory concentrations of the essential oil were tested in order to check its action on K. pneumoniae membrane permeability, capsule expression, urease activity and cell morphology. The MIC and MBC of the essential oil were 0.09 ± 0.01%. A complete inhibition of the bacterial growth was observed after 2 h of incubation with twice the MIC of the essential oil. A better MIC was found when neutral or alkaline pH broth was used. Alteration in membrane permeability was found by the increase of crystal violet uptake when the bacteria were incubated with twice the MIC levels of the essential oil. The urease activity could be prevented when all the subinhibitory concentrations were tested in comparison to the untreated group (p < 0.001). Alteration of the bacterial morphology besides inhibition of the capsule expression was verified by atomic force microscopy, and Anthony's stain method, respectively. Our data allow us to conclude that the essential oil of P. amboinicus can be a good candidate for future research.

This study determined the species of 54 staphylococci isolates from canine otitis and their ability to produce biofilm through the Congo red agar method, confirmed by scanning electron microscopy. The most frequently identified species were S. intermedius and S. simulans. Results showed that 30% of the strains were biofilm producers.

No abstract