Phenotypic and molecular characterization of Streptococcus mutans bacteria isolated from the mouth and test their ability to form biofilms and their resistance to antibiotics
Abstract
A total of 479 bacterial isolates were collect from 409 swabs from the teeth surfaces teeth and gingiva of the auditors admitted to the centers specialist and dental clinics in Al-Diwaniya city for different ages by specialist doctor on period from 1/11/2012 AC till 1/3/2013 AC. Bacterial isolates diagnosed by Vitek compact 2 system to positive and negative gram stain head it Streptococcus spp. by highest percentage of 31.52%, followed by Staphylococcus spp. by 20.45% and Lactobacillus spp. by 12.52% and Candida spp. by 10.64%, and follow then some germs that made a few percentages compared to the bacteria mentioned, also S. mutans obtain among microbial species isolated from teeth surfaces and gingiva frequency highest in the number of isolates (56 isolate) and tested their on biofilm formations; then 44 isolation (44.64%) high formations, 16 isolation (28.57%) medium formations and 15 isolation (26.79%) non biofilm formations. The impact of carbohydrates appear apparent on S. mutans isolates in biofilm formations on bio-growth medium; then amounted to the presence of sucrose 35.71%, followed by glucose with fructose together in the medium (25.00%) then glucose (16.07%) and fructose (12.50%), while the percentage of carbohydrates absence in the growth medium 10.71%.The drug sensitivity of S. mutans isolates were tested trend 11 antibiotic by using disks diffusion method which showed that the resistance of isolates to antibiotics was higher than the sensitivity of her as well as they were increase after biofilm formations; where resistant isolates convey to Erythromycin before and after biofilm formations (98.21 and 94.64)%, Amoxicillin (85.71)% each for both, and Ampicillin (80.35 and 83.92)%, Nalidixic acid (80.35 and 87.50)%, Cefotaxime (69.64 and 75.00)%, Chloramphenicol (69.64 and 89.28)%, Amoxicillin-Clavulanic acid (58.92 and 76.78)%, Gentamicin (57.14 and 78.57)%, Tetracycline (55.35 and 66.07)% each respectively, while showed high sensitivity to Amikacin (25.00 and 48.21)% and Trimethoprim sulfamethaxale (7.14 and 19.64)% each, respectively. 12 isolates elected tested from the 56 isolates of S. mutans; as a biofilm producer and more resistant to antibiotics and were containing 16s RNA gene was representing diagnostic gene for these bacteria using polymerase chain reaction (PCR) technique, results also showed DNA sequences of the conservative gene (16s rRNA) in isolates of S. mutans biofilm formations and by means of phylogenetic tree analysis for that gene, the similarity appeared between S. mutans local strain with Spain standard strain (AJ554208.1) in 14 and 15 nucleotide locations.
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