Zinc-Based Nanoparticles Reduce Bacterial Biofilm Formation.

Biofilm formation is important for microbial survival in hostile environments and a phenotype that provides microorganisms with antimicrobial resistance. Zinc oxide (ZnO) and Zinc sulfide (ZnS) nanoparticles (NPs) present potential antimicrobial properties for biomedical and food industry applications. Here, we aimed to analyze, for the first time, the bactericidal and antibiofilm activity of ZnS NPs against Staphylococcus aureus, Klebsiella oxytoca, and Pseudomonas aeruginosa, all medically important bacteria in developed countries. We compared ZnS NPs antimicrobial activity to ZnO NPs, which have been extensively studied. Using the colorimetric XTT reduction assay to observe the metabolic activity of bacterial cells and the crystal violet assay to measure biofilm mass, we demonstrated that ZnS and ZnO had similar efficacy in killing planktonic bacterial cells and reducing biofilm formation, with S. aureus being more susceptible to both therapeutics than K. oxytoca and P. aeruginosa. Crystal violet staining and confocal microscopy validated that Zn NPs inhibit biofilm formation and cause architectural damage. Our findings provide proof of principle that ZnS NPs have antibiofilm activity, and can be potentially used in medical and food industry applications, such as treatment of wound infections or package coating for food preservation. IMPORTANCE Zinc (Zn)-based nanoparticles (NPs) can be potentially used in medical and food preservation applications. As proof of principle, we investigated the bactericidal and antibiofilm activity of zinc oxide (ZnO) and zinc sulfide (ZnS) NPs against medically important bacteria. Zn-based NPs were similarly effective in killing planktonic and biofilm-associated Staphylococcus aureus, Klebsiella oxytoca, and Pseudomonas aeruginosa cells. However, S. aureus was more susceptible to these investigational therapeutics. Although further studies are warranted, our findings suggest the possibility of future use of Zn-based NPs in the treatment of skin infections or preservation of food.

Molecular detection of feline hemoplasmas and retroviruses in free-roaming and shelter cats within a university campus.

Objectives: The aim of the present study was to assess the frequency of hemoplasma, feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) infections in cats living in an on-campus shelter and free-roaming cats within a university campus in Brazil. Methods: Blood samples were tested using quantitative PCR for hemoplasma, FIV and FeLV. Positive hemoplasma samples were sequenced. Associations between hemoplasma detection and living situation, sex, flea and/or tick parasitism, and coinfection with FIV and FeLV, were assessed using Fisher's exact test and the respective odds ratios were calculated. Results: Overall, 6/45 (13.3%) cats tested positive: four (8.9%) were infected with 'Candidatus Mycoplasma haemominutum' and two (4.4%) with Mycoplasma haemofelis. All positive samples were from free-roaming cats (6/15; 40.0%) and had statistically significantly lower packed cell volumes (P = 0.037). Although 5/23 (21.7%) males and 1/22 (4.6%) females were positive, no statistically significant association between sex and hemoplasma infection was found (P = 0.19). Viral quantitative PCR (qPCR) was performed on 43/45 samples, among which 2/43 (4.7%) were positive for FIV and none for FeLV. Only one cat (2.3%) was coinfected with hemoplasma and FIV (P = 0.26). In addition, 4/6 (66.7%) cats that tested positive for hemoplasmas were infested by fleas (P = 0.0014) and/or ticks (P = 0.25). Conclusions and relevance: These results show that even if the free-roaming cat population is clinically healthy and has adequate access to food, it may present flea infestation and hemoplasma infection with lower packed cell volume values.

Isolation and Characterization of a Novel Pathogenic Strain of Ehrlichia minasensis.

The genus Ehrlichia is composed of tick-borne obligate intracellular gram-negative alphaproteobacteria of the family Anaplasmataceae. Ehrlichia includes important pathogens affecting canids (E. canis, E. chaffeensis, and E. ewingii), rodents (E. muris), and ruminants (E. ruminantium). Ehrlichia minasensis, an Ehrlichia closely related to E. canis, was initially reported in Canada and Brazil. This bacterium has now been reported in Pakistan, Malaysia, China, Ethiopia, South Africa, and the Mediterranean island of Corsica, suggesting that E. minasensis has a wide geographical distribution. Previously, E. minasensis was found to cause clinical ehrlichiosis in an experimentally infected calf. The type strain E. minasensis UFMG-EV was successfully isolated from Rhipicephalus microplus ticks and propagated in the tick embryonic cell line of Ixodes scapularis (IDE8). However, the isolation and propagation of E. minasensis strains from cattle has remained elusive. In this study, the E. minasensis strain Cuiabá was isolated from an eight-month-old male calf of Holstein breed that was naturally infected with the bacterium. The calf presented clinical signs and hematological parameters of bovine ehrlichiosis. The in vitro culture of the agent was established in the canine cell line DH82. Ehrlichial morulae were observed using light and electron microscopy within DH82 cells. Total DNA was extracted, and the full genome of the E. minasensis strain Cuiabá was sequenced. A core-genome-based phylogenetic tree of Ehrlichia spp. and Anaplasma spp. confirmed that E. minasensis is a sister taxa of E. canis. A comparison of functional categories among Ehrlichia showed that E. minasensis has significantly less genes in the 'clustering-based subsystems' category, which includes functionally coupled genes for which the functional attributes are not well understood. Results strongly suggest that E. minasensis is a novel pathogen infecting cattle. The epidemiology of this Ehrlichia deserves further attention because these bacteria could be an overlooked cause of tick-borne bovine ehrlichiosis, with a wide distribution.