Ação dos desinfetantes sobre a adesão e biofilme consolidado de Staphylococcus spp

Moraxella bovis, Moraxella ovis and Moraxella bovoculi: biofilm formation and lysozyme activity

AIMS

This study aimed to verify the formation of biofilms by Moraxella bovis, Moraxella ovis and Moraxella bovoculi isolates from ruminants. In addition, the lysozyme activity against the isolates of M. bovis, M. ovis and M. bovoculi in free form and in biofilms was determined.

METHODS AND RESULTS

In this study, 54 isolates of Moraxella sp. obtained from bovine and ovine clinical samples were evaluated in vitro for capacity of biofilm formation and lysozyme susceptibility in planktonic and sessile cells. In addition, biofilms produced by four Moraxella sp. isolates were visualized under scanning electron microscope (SEM). It was possible to demonstrate, for the first time, the ability to form biofilms by M. ovis and M. bovoculi. The isolates of Moraxella sp. have the capacity to form biofilms in different intensities, varying among weak, moderate and strong. It was verified that the lysozyme shows activity on Moraxella sp. in planktonic form. However, on biofilms there was a reduction in the production, but without impairing its formation, and on consolidated biofilms the lysozyme did not have the capacity to eradicate the preformed biofilms.

CONCLUSIONS

This work shows the capacity of biofilm formation by Moraxella sp. of veterinary importance. The lysozyme susceptibility of Moraxella sp. in planktonic form shows that this enzyme has bacteriostatic activity on this micro-organism and it reduced the production of biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

Based on the results, it is possible to infer that the biofilm formation capacity by Moraxella sp. and the resistance to lysozyme concentrations equal to or greater than the physiological levels of the ruminant tear may be linked not only to the capacity to colonize the conjunctiva, but also to remain in this place even after healing of the lesions, being a reservoir of Moraxella sp. in a herd.

Virulence Genes and Antimicrobial Resistance in Escherichia coli from Cheese Made from Unpasteurized Milk in Brazil

Cow raw milk cheese is widely eaten in Brazil. These products may be contaminated with pathogenic bacteria. In this work, we investigated the presence of Escherichia coli in raw milk cheese from different States in Brazil. From 147 "Minas" cheese samples, 28 cheeses were positive for E. coli. Among 39 E. coli isolates of the cheeses, one was positive for eae and negative for bpfA and efa1/lifA using PCR, and so was classified as atypical Enteropathogenic E. coli (aEPEC). Two other isolates were positive for extraintestinal pathogenic E. coli (ExPEC) genes. The aEPEC isolate belongs to serogroup O127 and was classified in A phylogenetic group, and ExPEC isolates were found in O73:H12 (EC-2 strain) and O64474:H8 (EC-9 strain) serotype. This ExPEC belongs to A and C phylogenetic group, respectively. Most of E. coli strains belonged to Clermont phylogenetic groups A (28.2%), C, and E (23.1%). Six strains (15.4%) of E. coli were positive for group B1 and two (5.1%) for B2. E. coli isolates presented an aggregative (46.0%) and diffuse (12.6%) adherence pattern to HeLa cells, and the other isolates did not show adhesion (41.4%). Four E. coli isolates (10.3%) were shown to produce moderate biofilm. The antimicrobial resistance rate was tetracycline (25.6%), followed by ampicillin (17.9%), cefoxitin (7.7%), nalidixic acid (5.1%), and amoxicillin-clavulanic acid (2.6%). One strain was resistant to three antimicrobials (tetracycline, ampicillin, and nalidixic acid). The presence of these microorganisms, the O127 strain, and a new serogroup in Brazil is a potential risk for public health.