الفهرس 
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Abstract
Pseudomonas aeruginosa is an important opportunistic pathogen which plays an important role in hospital intensive care units, causing a wide spectrum of nosocomial infections. The spread of this organism in health care settings is often difficult to control, due to the presence of multiple intrinsic and acquired mechanisms of resistance to a wide variety of antibiotics.
Pseudomonas aeruginosa isolates show steady escalation in resistance to an increasing number of antimicrobial agents and the emergence of multidrug resistant Pseudomonas aeruginosa infections is increasingly recognized.
This study aimed to determine the frequency of nosocomial infections caused by P. aeruginosa, The antibiotic resistance pattern for P. aeruginosa isolates was performed, the frequency of multidrug resistance among nosocomial P. aeruginosa infections and carbapenems antibiotic sensitivity pattern of P. aeruginosa isolates were determined by disc diffusion method. Phenotypic and genotypic detection of Metallo-β-lactamase production through PCR amplification of Metallo-β-lactamase genes, particularly (IMP and VIM) and biofilm production, and to define the risk factors for carbapenems resistance in p. aeruginosa infections.
This study included 845 clinical samples collected from nosocomially infected patients admitted to ICUs at AL-Azher University Hospital between November 2015 to April 2017.
The frequency of P. aeruginosa isolates among total uropathogens was 18% (74/412). Different samples were inoculated on different bacteriological media and were confirmed by biochemical reactions. A total of 74 strains of P. aeruginosa were isolated from total pathogens 18% (74/412). P. aeruginosa was isolated from patients in different ICUs and wards. The highest percentage of P. aeruginosa was found in Urology department representing 32.4% (24/74), , followed by General ICU representing 24.3% (18/74), Chest ICU and neurology ICU representing 10.8% (8/74), internal medicine ICU 9.5% (7/74), pediatric ICU 6.8% (5/74), and then postoperative ICU representing 5.4% (4/74).
According to antimicrobial susceptibility profile of 74 P. aeruginosa urine isolates toward the different antibiotic classes. The highest sensitivity was to imipenem 38 isolates (51.3%). The antibiotic sensitivity then decrease in descending manner to be meropenem (48.6%) > levofloxacin (28.4%) > ciprofloxacin and ceftazidime (21.6%) while the highest resistance rates were to carbenicillin 70 isolates (94.6%) then gentamicin (70.3%).
The MIC for imipenem and meropenem and was determined by IP and MP E-tests, respectively. E-test results showed that 36.5% of all 74 P. aeruginosa isolates were resistant to IP and 39.2% were resistant to MP.
The study was shown that out of 74 P. aeruginosa isolates, 51 (69%) strains were MDR and 23 (31%) strains were non-MDR strains.
Phenotypic detection of carbapenemases in all 74 isolated P. aeruginosa strains was also done by different methods as CDT and DDST using both IPM and MEM (10 μg) disks.
Imipenem- EDTA and Meropenem - EDTA combined disk tests were used to detect MβLs production in all 74 P. aeruginosa isolates. Out of the 74 P. aeruginosa isolates, 26 (35.1%) and 25 (33.8%) showed an increase in the zone of inhibition of about 7 mm or more around IPM-EDTA and MEM-EDTA disks compared to IPM and MEM disk alone (positive for MβLs production), respectively.
Concerning to DDST, Out of the total 74 P. aeruginosa isolates, 23 (31.1%) and 21 isolates (28.4%) showed positive results for MβLs production using IPM and MEM, respectively, but all IP and MP E-test susceptible P. aeruginosa isolates showed negative results of DDST.
The study showed that 44/51 (86.3%) of MDR strains were biofilm producer, more precisely; 33.33% of the strains were strong biofilm producers, 29.41% of strains were moderate biofilm producers and 23.53% of strains were weak biofilm producers.
The prevalence of both bla IMP-1 and bla VIM-1 gene among MßLs producing P. aeruginosa in urine isolates as follows 27 imipenem resistant isolates, 8 carried blaVIM but none of them had blaIMP was detected.
Out of 51 MDR P. aeruginosa strains, 34 (66.7%) strains were isolated from male patients and 17 (33.3%) strains were isolated from female patients.
Rate of distribution of MDR P. aeruginosa urine isolates among the different ages of patients with nosocomial MDR P. aeruginosa infection ranged from 5 years to 75 years. Among the (5-20) years old patients, the rate of MDR P. aeruginosa strains was 5.9%; among (21-40) years old patients; it was 17.7%; among the (41-60) year’s old patients, it was 31.4% and among the (61-75) years old patients, it was 45.1%.
The most prevalent risk factors associated with the occurrence of nosocomial MDR P. aeruginosa infection were prior antibiotic treatment (p value= 0.02), and the presence of a urinary catheter (p value= 0.004). Regarding to age, sex, central line in ICU, parentral nutrition and diabetes mellitus variables, P value was not significant.