In this study, out of 50 isolates of some nosocomial infections from some Baghdad hospitals, only 13 (26%) were identified as Escherichia coli. Depending on selective media, morphological and biochemical tests the species was then confirmed by molecular methods. Later on  antimicrobial resistance test was performed by the Kirby-Bauer method. The molecular characterization of blaTEM and blaCTX-M genes in different clinical isolates of E. coli was done through polymerase chain reaction (PCR) by utilizing special primers. These genes were positive to only 4 (30.7%) isolates. The sequence of nucleotides of positive genes was carried out for four isolates. The results showed that there was no variance in the nucleotide sequence between Iraqi isolates compared with the global isolates, and that they were 100% identical to many genera of Enterobacteriaceae. Finally, due to the indiscriminate use of antibiotics, these genes in human strains were likely the source of widespread drug resistance.

In this study out of 50 isolates of burns infections only 15(30%) was identified as Pseudomonas aeruginosa depending on selective media, morphological and biochemical tests then confirmed by using VITEK-2 Compact system. The pilB virulent gene was present in 15 (100%) isolates depending on PCR by using specific primers of pilB gene (826bp). The nucleotides pilB sequence has been done to nine isolate, Results displayed occurrence of some substitution gene mutations from (100-90.05%) identity with the reference sequence gene of the global strain with accession no. (pilB-879459) by alignment in NCBI and the phylogenetic tree was drew by using Geneious software. The analysis of phylogenetic tree showed five different groups of variations. The code isolates (3-pilB , 5-pilB , 9-pilB and 11-pilB) were chosen and documented in NCBI as anew Iraqi isolates and accepted under these accession numbers respectively (LC 546092, LC 546093, LC 546094 and LC 546095) of nucleotides sequence. Sequencing of pilB displayed the divergence between the Iraqi and global isolates might be due to the mutations that caused genetic variation in nucleotides content.

The present work aimed to investigate the neuraminidase (nan1) gene expression in 32 different clinical isolates of Pseudomonas aeruginosa to explore the role of the enzyme in different types of infection and might give a better understanding of host cell-pathogens interaction. In addition, the effect of monosaccharide D-mannose on neuraminidase gene expression in eight isolates was studied by utilizing a reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The results demonstrated that the highest expression of nan1 gene was in otitis samples (208,913.81) which were significantly higher than that from other infections (P < 0.01). While, the concentrations of gene copies obtained from urine, sputum and burns samples were 93,535.34, 92,254.64 and 74,029.63respectively. While the least expression in wound samples (32,017.06). This suggests that neuraminidase in ear samples might be more virulent and invasive followed by that from urine, sputum, burns and wounds samples. The considerable interest of addition D-mannose significantly reduced the rate of neuraminidase activity reached fivefold in some isolates. This indicates that D-mannose down regulates nan1 gene expression. Hence, this sugar could be used in the development of potential new antibacterial agents where it acts as a competitive neuraminidase inhibitors.