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التحليل لبعض عوامل الضراوة لبكتريا Pseudomonas aeruginosa المعزولة من مصادر التليف الحوصلي وغير التليف الحوصلي
Author name:
ايمان ثامر جار الله
Supervisor name:
سوسن ساجد محمد علي الجبوري
General topic:
Biology
Specific topic:
Microbiology - Bacteria
Degree:
Master
University:
Mustansiriyah University - College Of Science
Language:
English
University location:
Baghdad
First pages:
24T3210 - p.pdf
Abstract:
This study concerned with illustration the molecular pattern of virulence genes in P. aeruginosa isolated from cystic fibrosis (CF) and compared them with those of none CF isolates (different nosocomial infections). The study involves the following steps : · Twenty - six isolates of P. aeruginosa were obtained from patients submitted to Baghdad hospitals/Iraq during the period between July 2013 until December 2013. These isolates were distributed as 6 isolates from blood, 4 isolates from urinary tract infections andsputum (for each), 3 isolates from wounds and ear infections (for each), 2 isolates from bronchial wash of patients suffering respiratory tract infection beside 4 isolates from cystic fibrosis patients. · The isolates were initially identified by culturing on MacConkey agar and P. aeruginosa agar then diagnosed by performing some morphological and biochemical tests. The second diagnoses was done by api 20NE system followed by Genotypic diagnoses usingpolymerase chain reaction (PCR) depending on a housekeeping gene rpsl gene (amplified size was 201bp). The results revealed that all the 26 isolates were P. aeruginosa.· Genotypic detection of many virulence factors related to P. aeruginosa was performed using conventional PCR. They included : gene coded for exoenzyme S (exoS, 504bp), exotoxin A (toxA, 352bp), two phospholipases C encoded by (plcH, 307bp) and (plcN,466bp), alginate (algD, 1310bp), (lasB, 300bp), putative silidase (Pseudoaminidase, 1500bp) and Neuraminidase (nan1, 1316bp). · The results revealed that the most frequently gene was exoS when it was detected in 21/26 (80.7%) and distributed between 19 in different clinical source and 4 in CF samples. For toxA the rate was 19/26 (73%) and all CF isolates were positive to this gene as with exoS. The percentage of other genes were, plcH 13/26 (50%), plcN 18/26 (69.2%), algD17/26 (65.3%) {All CF isolates were positive}. For lasB gene it was detected in 8/26 (30.7%), sialidase (Pseudoaminidase) in 4/26 (15.38%) isolate, one of source was CF and the others distributed between bronchial wash and ear infections. The last gene was nan1 and only one CF isolate 1/26 (3.8%) harbored this gene.· DNA sequencing and phylogenic analysis for exoS, toxA, plcH, algD, nan1 and sialidase (Pseudoaminidase) genes were done using Pairwise alignment and Tamura - Nei genetic destine model, UPGMA (Un weighted Pair Group Method with Arithmetic Mean) tree build, respectively. Results of DNA sequencing for exoS and toxA genes revealed that most isolates display different point mutation as compared with the NCBI data. Point mutation type transversion was detected in residue no. 17 base 52 in P. aeruginosa exoSBW1 isolated from bronchial wash causes alteration of Thyamine to Adenine and conversion of Leucine residue to Glutamine. Another point mutation type transition occured in exoSB1, exoSU1 and exoSCyF1 in residue no. 18 base 55 when Guanine converted to Adenine cause conversion of Serine residue to Asparagine. P. aeruginosa exoSB3 and exoS CyF2 isolated from blood and cystic fibrosis, respectively, showed high similarity made them segregate within the same group or clone, while exoSU2 and U3 were within the same clone but neither with exoS U1 nor U4. · Another point mutation was detected in P. aeruginosa toxA CyF2, when nitrogen base Guanine no. 36 residue 12 was changed to Adenine causes conversion of Arginine to Histidin. Also mutation occur in toxA - CyF1, 2, 3, 4, toxA U1, 2, 3, 4 and toxA BI, BW1 whennitrogen base Adenine no. 132 residue 44 was converted to Guanine causes the conversion of Threonine to Alanine. Such difference may explain the diversity of virulence in some isolates.· DNA analysis for plcH was performed to amplified fragment related to CyF3. The identity of Pairwise alignment with the origin gene related to NCBI was 100% and no mutation was detected. · For algD, result revealed that a point mutations were detected in many residuse but the interest finding is that all of these mutations were silent specially in CyF2, since it didn’t change amino acid sequence, while the mutation that was delectated in P. aeruginosa algD Ear1 causes alteration in amino acid sequence when nitrogen base Guanine no. 388 residue 130 was converted to Adenine thus the conversion of Glycine to serine. The percentage of Pairwise identity was 95.4% which represent the percentage of identical residues in the alignment including gap and non gap residues .· For nan1 gene, many mutations were noticed in this amplified fragment but some of them were silent while others were defective cause alteration in frame translation in many residues. · DNA sequence for silidase (Pseudoaminidase) gene related to P. aeruginosa CyF3 and Pairwise alignment for this gene was performed (forward and reverse sequences data). The data was compared with control obtained from NCBI gene bank. The identity was 82% with some gaps occur in identity due to differences in base pair sequence as a result from changing some nitrogen bases. Most of these mutation were silent mutation after translated to amino acid. Others were not.· From all above results, it could be said that some isolates displayed highly virulence pattern specially in CF isolates as compared with non - CF isolates. P. aeruginosa was unique in harboring all the detected virulence genes and most of them were mutant.
