Streptococcus mutans is one of the major cariogenic microbial flora. In an attempt to determine the mutagenic effect of diode laser on the viability and antibiotic sensitivity of this bacteria; A total of 30 samples were collected from dental caries. The isolates were identified using by conventional identification methods and confirmed using VITEK2 system. Twenty-one isolates were recorded as Streptococcus spp and ten of them were identified as Streptococcus mutans. Antibiotic susceptibility profile for Streptococcus mutans isolates against ten antibiotics was tested. The results revealed that all the isolates were resistant to cefixime and cephalothin, nine of them were resistant to erythromycin, ampicillin, and nalidixic acid, seven isolates were resistant to tetracycline and bacitracin, whereas all isolates were sensitive to chloramphenicol, ciprofloxacin and gentamycin. The effect of the diode laser on the isolates (S5 and S10) was tested at different time intervals (1, 2, 5, and 10) min. The viability of Streptococcus mutans isolates was affected by the obvious change in the behaviour of the bacteria from resistance to sensitivity after Laser exposure

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Treatment with herbal drugs is considered one of the oldest and safest methods for treating various diseases. Mentha arvensis is a medicinal plant used worldwide in the pharmaceutical industry for its antibacterial, anticancer, antiallergic, and anti-inflammatory properties. In the present study, the antibacterial activity of the methanolic extract of M. arvensis leaves was tested at different concentrations (50, 100, 150, and 200 µg/ml) against bacteria isolated from human burn wound infections, including Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus. The results demonstrated that at concentrations of 100, 150, and 200 µg/ml, the methanolic extract exhibited strong antibacterial activity against S. aureus and P. aeruginosa, while K. pneumoniae isolates were resistant to the extract at all tested concentrations. Further, the cytotoxic activity of the methanolic extract was assessed at various concentrations (100, 140, 160, 180, 220, and 250 µg/ml) against two cell lines: the RD tumor cell line and Vero normal cell line. The higher concentrations of the extract (220 and 250 µg/ml) showed potent cytotoxic effects on the RD cell line after 72 hours in a dose- and time-dependent manner. In contrast, the extract exhibited lower cytotoxic effects on Vero cells at the same concentrations after 72 h.

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Tonsillitis which is commonly referred to a strep throat is caused by group A β-hemolytic streptococci (GABHS) or Streptococcus pyogenes. The bacteria is consider as one of the major human-specific bacterial pathogen and one of its virulence factors is the streptokinase; for this reason, 100 tonsillitis swabs were taken from Iraqi children suffering from symptoms of sore throat. Using conventional cultural methods, 60 bacterial isolates were characterized and subjected to biochemical tests. As a result, 40 isolates were identified as hemolytic bacteria and only 6 of them were identified as Streptococcus. pyogens using Bacitracin (0.04) and Vitek 2 system. The ability of the 6 isolates for streptokinase production was screened and the results showed that all of them were produce the enzyme with variable degrees. Molecular detection of streptokinase gene using real time PCR technique has been done with specific primers and the amplification results were present with all S.pyogens strains.