Evaluating the antimicrobial and anti-biofilm activity of three synthetic antimicrobial Citropin analogs and their ability to fight against Staphylococcus aureus and Staphylococcus pseudintermedius.

AIMS: We developed three new analogs of the antimicrobial peptide (AMP) Citropin 1.1: DAN-1-13, AJP-1-1, and HHX-2-28, and tested their potential antimicrobial and anti-biofilm activities against S. aureus and S. pseudintermedius. Potential cytotoxic or hemolytic effects were determined using cultured human keratinocytes and erythrocytes to determine their safety. METHODS AND RESULTS: To assess the antimicrobial activity of each compound, minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) were determined against methicillin-resistant and methicillin-susceptible strains of S. aureus and S. pseudintermedius. Activity against newly formed and mature biofilms was determined in two clinical isolates using spectrophotometry and scanning electron microscopy (SEM). All three compounds exhibited antimicrobial and bactericidal activity against all studied S. aureus and S. pseudintermedius strains, with MICs ranging from 4-32 µg ml- 1 and MBCs ranging from 8-128 µg ml- 1. Subinhibitory concentrations of all compounds also showed anti-biofilm activity in the two tested isolates. All compounds exhibited limited cytotoxic and hemolytic activity. CONCLUSION: Novel analogs of Citropin 1.1 exhibit anti-microbial and bactericidal activities against S. aureus and S. pseudintermedius isolates and inhibit the biofilm formation of these bacteria.

Evaluation of changes in antimicrobial susceptibility in bacteria infecting children and their mothers in pediatric, neonatal-intensive care unit, and gynecology/obstetrics wards of a quaternary referral hospital during the COVID-19 pandemic.

The World Health Organization released a statement warning of increased risk for the incidence of multidrug resistant microorganisms and the absence of new drugs to control such infections soon. Since the beginning of the COVID-19 pandemic, the prescription of antimicrobial agents has increased and may have accelerated the emergence of multidrug resistant (MDR) bacteria. This study aimed to evaluate maternal and pediatric infections within a hospital from January 2019 to December 2021. An observational retrospective cohort study was performed at a quaternary referral hospital in a metropolitan area of Niteroi city, Rio de Janeiro state, Brazil. A total of 196 patients' medical records were analyzed. The data from 90 (45.9%) patients were collected before the SARS-CoV-2 pandemic, 29 (14.8%) from the 2020 pandemic period, and 77 (39.3%) from the 2021 pandemic period. A total of 256 microorganisms were identified during this period. Out of those, 101 (39.5%) were isolated in 2019, 51 (19.9%) in 2020, and 104 (40.6%) in 2021. Antimicrobial susceptibility tests were performed on 196 (76.6%) clinical isolates. The exact binomial test showed that the distribution of Gram-negative bacteria was predominant. The most common microorganism was Escherichia coli (23%; n = 45), followed by Staphylococcus aureus (17.9%, n = 35), Klebsiella pneumoniae (12.8%, n = 25), Enterococcus faecalis (7.7%, n = 15), Staphylococcus epidermidis (6.6%, n = 13) and Pseudomonas aeruginosa (5.6%, n = 11). Staphylococcus aureus was the predominant species among resistant bacteria. Among the antimicrobial agents tested, the following were resistant, presented on a descending scale: penicillin (72.7%, p = 0.001, Binomial test), oxacillin (68.3%, p = 0.006, Binomial test), ampicillin (64.3%, p = 0.003, Binomial test), and ampicillin/sulbactam (54.9%, p = 0.57, Binomial test). Infections with S. aureus were 3.1 times greater in pediatrics and maternal units than in other hospital wards. Despite the global reduction in the incidence of MRSA, we observed an increase in MDR S. aureus in this study. No changes were observed in the frequency of resistance profiles of the clinical isolates after the establishment of the global SARS-CoV-2 pandemic. More comprehensive studies are needed to understand the impact of the global SARS-CoV-2 pandemic on the resistance levels of bacteria associated with neonate and pediatric patients.

'Hypericum brasiliense: bactericidal and antibiofilm activity against Staphylococcus aureus in vitro'.

Staphylococcus aureus is considered the most common opportunistic pathogen in humans, capable of forming biofilm, increasing the chances of antibiotic resistance and causes several chronic diseases. Biodiversity is a source of inspiration in the search for new agents against these microorganisms. Hitherto, the efficacy of Hypericum sp. extracts as an antibacterial agent has already been demonstrated against Gram-positive and Gram-negative bacteria. In this study, we observed that until 4 µg/mL, the Hypericum brasiliense extract showed bactericidal activity against a clinical multidrug-resistant S. aureus strain (HU25) and also inhibited biofilm formation at 1/2xMIC (confirmed by SEM) and 1/4xMIC. The extract was also proportionally active against 6 h-preformed biofilm to its concentration (1/2xMIC, 1/4xMIC, p value ≤ 0.05). These promising results make Hypericum brasiliense extract a strong candidate to treat S. aureus infections, including anti-biofilm therapy.

Virulence Factors Found in Nasal Colonization and Infection of Methicillin-Resistant Staphylococcus aureus (MRSA) Isolates and Their Ability to Form a Biofilm.

Hospitalizations related to Methicillin-resistant Staphylococcus aureus (MRSA) are frequent, increasing mortality and health costs. In this way, this study aimed to compare the genotypic and phenotypic characteristics of MRSA isolates that colonize and infect patients seen at two hospitals in the city of Niterói-Rio de Janeiro, Brazil. A total of 147 samples collected between March 2013 and December 2015 were phenotyped and genotyped to identify the protein A (SPA) gene, the mec staphylococcal chromosomal cassette (SCCmec), mecA, Panton-Valentine Leucocidin (PVL), icaC, icaR, ACME, and hla virulence genes. The strength of biofilm formation has also been exploited. The prevalence of SCCmec type IV (77.1%) was observed in the colonization group; however, in the invasive infection group, SCCmec type II was prevalent (62.9%). The Multilocus Sequence Typing (MLST), ST5/ST30, and ST5/ST239 analyses were the most frequent clones in colonization, and invasive infection isolates, respectively. Among the isolates selected to assess the ability to form a biofilm, 51.06% were classified as strong biofilm builders. Surprisingly, we observed that isolates other than the Brazilian Epidemic Clone (BEC) have appeared in Brazilian hospitals. The virulence profile has changed among these isolates since the ACME type I and II genes were also identified in this collection.

Biological Evaluation of Selected 1,2,3-triazole Derivatives as Antibacterial and Antibiofilm Agents.

BACKGROUND: Resistance to antimicrobial agents is a major public health problem, being Staphylococcus aureus prevalent in infections in hospital and community environments and, admittedly, related to biofilm formation in biotic and abiotic surfaces. Biofilms form a complex and structured community of microorganisms surrounded by an extracellular matrix adhering to each other and to a surface that gives them even more protection from and resistance against the action of antimicrobial agents, as well as against host defenses. METHODS: Aiming to control and solve these problems, our study sought to evaluate the action of 1,2,3- triazoles against a Staphylococcus aureus isolate in planktonic and in the biofilm form, evaluating the activity of this triazole through Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) tests. We have also performed cytotoxic evaluation and Scanning Electron Microscopy (SEM) of the biofilms under the treatment of the compound. The 1,2,3-triazole DAN 49 showed bacteriostatic and bactericidal activity (MIC and MBC 128 µg/mL). In addition, its presence interfered with the biofilm formation stage (1/2 MIC, p <0.000001) and demonstrated an effect on young preformed biofilm (2 MICs, p <0.05). RESULTS: Scanning Electron Microscopy images showed a reduction in the cell population and the appearance of deformations on the surface of some bacteria in the biofilm under treatment with the compound. CONCLUSION: Therefore, it was possible to conclude the promising anti-biofilm potential of 1,2,3-triazole, demonstrating the importance of the synthesis of new compounds with biological activity.