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Streptococcus pyogenes are associated with many bacterial diseases in both humans and animals and are capable of causing a multitude of human diseases. S. pyogenes isolates were identified by their bacitracin sensitivity, positive spy1258 detection, and positive GAS latex agglutination. Different isolates were typed serotypically and genotypically by BOX-PCR. Different virulence factors were identified in S. pyogenes isolates. In addition, antimicrobial resistance was tested to eleven different antibiotics. Furthermore, the resistance mechanisms were determined phenotypically by the disc diffusion method. Finally, the correlation between both molecular and serotypes identified and the profile of virulence factors and clinical and geographical sources was determined for all isolates. Thirty-eight S. pyogenes isolates were collected from different clinical sources. Resistance testing indicated high resistance to mostly used antibiotics except amoxicillin/clavulanic acid, amoxicillin, and ampicillin. Serotyping results indicated five different serotypes, M1, M2, M3, M4, and M6, in S. pyogenes isolates, while six isolates were identified as untypeable. In addition, positive PCR results identified most of the tested SAgs genes in which speJ gene was mostly identified followed by speI, speC, and ssa genes being identified in 81.6%, 63.3%, 60.5%, and 60.5%, respectively. However, speH was the least detected. In contrast, speL, speM, and smeZ genes could not be detected in all tested isolates. Finally, BOX-PCR molecular typing was a more effective clustering method when compared to the serotyping method in all S. pyogenes. In conclusion, the isolates in this study were highly resistant to mostly used antibiotics. M1 was the most identified serotype. No significant association was found between serotypes, BOX-PCR cluster groups, and SAgs genes profiles. However, by the application of BOX-PCR, effective molecular typing was obtained.

Staphylococcus aureus is considered the most common causative agent of community and hospitalacquired infections. The isolates with increased virulence and antimicrobial resistance, especially mecithillin resistant S. aureus (MRSA), represent a challenge in hospitals and health care facilities worldwide. The effect of tyrosol, a phenolic quorum sensing compound of Candida albicans, was studied on the sensitivity of clinical MRSA isolates to antibiotics. Besides having antibacterial activity, subinhibitory concentrations (3.5-14.3 mM) of tyrosol increased the susceptibility to antimicrobial. It gave either synergistic or additive effect when combined with gentamicin, amikacin and ciprofloxacin. Also, the effect of such concentrations on virulence factors production was investigated. Biofilm formed was significantly decreased in most of the tested isolates (P≤0.0001). In addition, it significantly decreased the production of protease and lipase enzymes. Overall, these results represent a promising method for inhibiting S. aureus either by reducing its resistance to antibiotics or decreasing the production of virulence factors.

Introduction: Pseudomonas aeruginosa is considered a dangerous pathogen, as it causes many human diseases, besides that it is resistant to almost all types of antibacterial agents. So, new strategies to overcome P. aeruginosa infection have evolved to attenuate its virulence factors and inhibit its quorum-sensing (QS) activity. Purpose: This study investigated the effect of tyrosol and EDTA as anti-quorum-sensing and antivirulence agents against P. aeruginosa PAO1. Methods: Anti-quorum activity of sub-minimum inhibitory concentrations (sub-MICs) of tyrosol and EDTA was tested using Chromobacterium violaceum (CV 12,472) biosensor bioassay. Miller assay was used to assess the inhibition of QS signal molecules by βgalactosidase activity determination. Also, their effects on the production of protease, lipase, lecithinase, and motility were tested. The inhibitory effects of these molecules on QS regulatory genes and exotoxins genes expression were evaluated by real-time PCR. Results: Tyrosol and EDTA at sub-MICs inhibited the production of violacein pigment. Both compounds inhibited QS molecules production and their associated virulence factors (protease, lipase, lecithinase, and motility) (P≤ 0.05). Besides, the expression levels of QS regulatory genes (lasI, lasR, rhƖI, rhIR, pqsA, and pqsR) and exotoxins genes (exoS and exoY) were significantly reduced (P≤ 0.05). Conclusion: Both tyrosol and EDTA can be used to fight P. aeruginosa infection as antiquorum-sensing and antivirulence agents at their sub-MICs.