دراسة فسلجية وجزيئية للبكتريا Lactobacillus reuteri ATCC 23272 وتاثيرها التثبيطي على البكتريا المسببة لالتهاب المهبل == Physiological and Molecular Study of Lactobacillus reuteri ATCC 23272 and its Inhibitory Effect on the Bacterial Vaginosis
Author name:
سارة هيثم صديق النعيمي
Supervisor name:
خالد عبد الرزاق حبيب
General topic:
Biology
Specific topic:
Microbiology - Bacteria
Degree:
Master
University:
University of Baghdad
Language:
English
University location:
Baghdad
First pages:
24T3318 - p.pdf
Abstract:
Bacterial vaginosis which is a common infection affecting the female genital tract, can be treated with different methods. One of these methods is the use of probiotic Lactic acid bacteria. The aim of this study was to evaluate the effects of two physiological factors (temperature and pH) on the growth and inhibitory action of probiotic Lactobacilli against the pathogenic Streptococcus agalactiae involved in bacterial vaginosis.A total of one hundred and six vaginal swabs were collected from Iraqi women patients affected with bacterial vaginosis, who attend Gynecological Department of Kamal Al - Samarraiy Hospital, Al - Qanat health care center, and private specialized clinics from October 2014 till March 2015, in order to obtain one hundred Streptococcus species. These swab samples were examined directly at the first. Isolated microorganisms were identified through microscopical, morphological, biochemical tests, and Vitek 2 compact system.The results showed that out of 243 bacterial isolates, 146 (60.08%) were detected as Gram - positive bacteria, whereas 97 (39.91%) were detected as Gram - negative bacteria. A hundred (68.49%) isolates of the Gram - positive bacteria were catalase - negative, while the rest 46 (31.51%) were catalase - positive.For all Gram positive, catalase negative bacteria, the results of the biochemical test and Vitek 2 compact system showed that the most frequent isolated microorganism was Streptococcus agalactiae 57 (57%), followed by Streptococcus faecalis 19(19%), Streptococcus sanguinis 13 (13%),Streptococcus salivarius 6 (6%), Streptococcus ovis 4 (4%), and Streptococcus suis 1(1%).The molecular method using the PCR technique was performed on the most prevalent species Streptococcus agalactiae to detect its virulence factors in order to prove its pathogenicity, the results revealed that, the HylB gene which is responsible for the production of hyaluronate lyase, appeared in 56 out of 57 isolates of S. agalactiae and the CylE gene which is responsible for the hemolysis of the red blood cells, appeared in 53 out of 57 isolates. These virulent isolates were involved in the physiological study.Lactobacillus reuteri ATCC 23272 was used in this study to investigate its effect as probiotic bacteria on the pathogenic bacteria (S. agalactiae). It was cultivated in MRS broth, adjusted to specific initial pH (3.5, 5, 6.5, 8), and at different temperatures of incubation (25°C, 30°C, 37°C, 44°C).The results revealed that the temperature of incubation and the initial pH of the culture medium effected significantly on both the growth rate and the antibacterial activity of the L. reuteri ATCC 23272. The temperature 30 °C with the pH 5 were recorded as the best conditions for the antibacterial activity in which the zone of inhibition was (18.2 mm), while the temperature 25 °C with the pH 3.5 resulted in the lowest inhibition zone (0.05mm).The maximum growth rate with an O.D. 1.9297 nm of the L. reuteri ATCC 23272 was obtained at temperature. 30°C and pH 6.5, and the minimum growth rate with an O.D. 0.0002 nm were obtained at temperature 25 °C and pH 3.5.There was a positive correlation between the growth rate of the Lactobacillus reuteri ATCC 23272 and the zone of inhibition.The optimal growth conditions were recorded in MRS broth, with an initial pH of 5 and a temperature of 30°C and this condition also had parallel effect on the maximum antibacterial activity of the L. reuteri ATCC 23272 against S. agalactiae associated with bacterial vaginosis.
