Host-microbiome interactions regarding peri-implantitis and dental implant loss.

In the last decades, the ortho-aesthetic-functional rehabilitation had significant advances with the advent of implantology. Despite the success in implantology surgeries, there is a percentage of failures mainly due to in loco infections, through bacterial proliferation, presence of fungi and biofilm formation, originating peri-implantitis. In this sense, several studies have been conducted since then, seeking answers to numerous questions that remain unknown. Thus, the present work aims to discuss the interaction between host-oral microbiome and the development of peri-implantitis. Peri-implantitis was associated with a diversity of bacterial species, being Porphiromonas gingivalis, Treponema denticola and Tannerella forsythia described in higher proportion of peri-implantitis samples. In a parallel role, the injury of peri-implant tissue causes an inflammatory response mediated by activation of innate immune cells such as macrophages, dendritic cells, mast cells, and neutrophils. In summary, the host immune system activation may lead to imbalance of oral microbiota, and, in turn, the oral microbiota dysbiosis is reported leading to cytokines, chemokines, prostaglandins, and proteolytic enzymes production. These biological processes may be responsible for implant loss.

Low performance of Policimbac® broth microdilution in determining polymyxin B MIC for Klebsiella pneumoniae.

Klebsiella pneumoniae is a global threat to healthcare, and despite the availability of new drugs, polymyxins are still an important therapeutic option for this and other resistant gram-negative pathogens. Broth microdilution is the only method that is recommended for polymyxins. In this study, we evaluated the accuracy of a commercial Policimbac® plate in determining the polymyxin B MIC for K. pneumoniae clinical isolates. The results were compared with those of the broth microdilution method according to ISO 16782. The Policimbac® plate had an excellent 98.04% categorical agreement, but unacceptable 31.37% essential agreement rates. Almost 2% of major errors as observed. Additionally, 52.94% of the strains overestimated the MIC at 1 µg/mL. Three isolates were excluded from the analysis due to the drying of the Policimbac® plate. To avoid dryness, we included wet gauze for the test, obtaining a 100% of categorical agreement rate; however, a low essential agreement was maintained (25.49%). In conclusion, the Policimbac® plate was unable to correctly determine the polymyxin B MIC for K. pneumoniae isolates. This low performance may interfere with the clinical use of the drug and, thus, with the result of the patient's treatment.

Biochemical and Toxinological Characterization of Venom from Macrorhynchia philippina (Cnidaria, Hydrozoa).

Macrorhynchia philippina is a colonial benthic hydroid from the Class Hydrozoa (Phylum Cnidaria) distributed in the tropical and subtropical marine waters from Atlantic Ocean, Indo-Pacific, and Mozambique. Its colonies somewhat resemble plants, causing confusion in the bathers who accidentally touch the animal. Acute burning/local pain, edema, erythema, and pruritus were symptoms already described, but its venom composition is unknown, as well as the participation of toxins for the symptom's development. Thus, herein, we show the biochemical composition and toxic effects of M. philippina venom. Colonies were collected and processed for histological analysis; alternatively, they were immersed into methanol containing 0.1% acetic acid for venom attainment, which was analyzed by mass spectrometry and submitted to edema and nociception evaluation in mice, hemolysis and antimicrobial assays in vitro. Before the molecule's extraction, it was possible to see the inoculation structures (hydrocladiums and hydrotheca) containing venom, which was released after the immersion of the animal in the solvents. The venom was composed mainly by low molecular mass compounds, able to cause significant reduction of the paw withdrawal latency from the hot plate test, 30 minutes after the injection. Moreover, significant edema was observed 10 and 30 minutes after the injection, indicating the activity of at least two inflammatory mediators. The venom caused no hemolytic activity but reduced the growth of A. baumannii and K. pneumoniae strains. This study is the first biochemical description of M. philippina venom, with molecules that cause fast inflammatory and painful effects, characteristic of the envenomation.