Maintenance of sterility in SMS packaging in dental environments: concern with biosafety

Healthcare services must be guided by biosafety practices and microbial control. This control is highly influenced by humidity, which directly impacts the maintenance of sterility of the materials used in the appointments. High concentration of moisture, in the form of aerosol, splashes and spills, is caused during dental care. During the COVID-19 times the contamination by aerosol and droplets worries greatly. Considering that it could cause harm to the sterility of an autoclaved material, especially in dental environments, the objective was to evaluate the behavior of SMS sterilization packages (Spunbonded / Meltblown / Spunbonded) against microbial penetration in an aqueous vehicle. SMS of three brands were challenged, equally divided into two groups: virgin and processed (subjected to a single autoclaving cycle). Each specimen was aseptically deposited on Macconkey agar. Subsequently, 5 µL of Escherichia coliATCC 25922 saline solution [108CFU mL-1] was deposited in center of the SMS specimen and the dish incubated at36°C/ 48h. Reading was performed by the presence or absence of bacterial growth typical of the species under the SMS, observed on the back of Petri dish. The lowest penetration rate observed was 60% for one of the brands in the virgin condition, and 75% for two brands in the processed condition. Statistical analysis showed an association between bacterial penetration and the evaluated group, this association being valid only in the virgin condition. The different SMS behave similarly in terms of resistance to bacterial penetration after being processed. The data show that moisture can assist in bacterial transport through sterilized SMS. Therefore, SMS packages are not able to prevent bacterial penetration, and possibly other microorganisms, when in aqueous vehicles, offering a potential risk of breaking the aseptic chain. Thus, care must be taken in routines for handling and storage sterile packaging.

Searching for mechanisms of action of antimicrobials.

Although development of antimicrobial resistance by bacteria is a natural phenomenon, the antibiotic resistance crisis is a reality that leads us in a gap of antimicrobial alternatives on therapeutics. Considering this cruel reality and committed to contribute to look for new antibacterial agents, this manuscript presents a review of easy laboratory methods that evaluate the mode of action of compounds, since it is a basic requirement for the discovery and development of new drugs. The literature was screened by searching the keywords "mode of action", "antibiotic", "antimicrobial activity", "inhibition mode", "method" and "bacteria" in Pubmed, Scopus, Science Direct and BVS in a period of time from 2000 to 2019. This review demonstrates the wide variety of methods that can be employed in research on mechanisms of action of antibacterial substances. Therefore, we compiled different protocols (presented in the supplementary material), available in the literature, with the purpose of facilitating the start of experiments.