الفهرس 
EnterococcusOnly 14 pages are availabe for public view
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Abstract
In recent years enterococci have increasingly become responsible for serious clinical and nosocomilal infections, including endocarditis, bacteremia, and urinary tract infections. They are now recognized as the most prevalent cause of nosocomial bacteremias. The increase in incidence of enterococcal infections is partly a result of increasing the risk factors e.g. immunocomprmized patients but is also a result of the spread of the multi-resistant enterococci. The increase in glycopeptide resistance among enterococci is of clinical concern in itself but also because enterococci can transfer antibiotic resistance genes to Staphylococcus aureus. VRE are now an increasingly important universal problem in hospitals worldwide. This study was performed at the National Liver Institute to estimate the frequency of isolation of enterococci and to study their antibiotic resistance pattern and plasmid profiles. Moreover detecting vancomycinresistant enterococci by both disc diffusion method and E-test from patients at different wards of the Institute. This study covered a period of about two years (August 2004 to August 2006). Samples were obtained from 200 hospitalized cases. And 66 samples were taken from hospital staff members and environment. All samples obtained were cultured on bile esculine, blood and Macconkey agar. No enterococci were detected from samples taken from medical staff or environment. While 43 enterococci were isolated from studied patients. Enterococci were identified by their morphology, catalase test (positive), PYR test (positive) and growth in 6.5% NaCl for 3 days. from this study we found that:- - That the most frequent isolate was E. coli (25.7%) followed by Klebsiella spp (21.9%), enterococci 43 (20.5%), Staphylococcus aureus (20%), Candida spp. (3.8%), Pseudomonas spp. (2.4%), Viridans streptococci (1.9%), Proteus spp. (1.4%), Staphylococcus saprophyticus (1.4%) and Staphylococcus epidermidis (0.95%). Among the cultured specimens, 10 (5%) cases showed no bacterial growth, while 20 (9.5%) patients showed mixed infections. - Enterococci were isolated from different wards: The highest rate (31.8%) was found in ICUs, followed by (25.4%) from surgical wards, then (15.6%) from wards of internal medicine and (12.5%) from pediatric wards. - Enterococci were significantly isolated from patients with liver transplantations (35.7%) and those with invasive procedures (23.3%). - The Highest rate of isolation was found in patients with age group between 40-50 years (32.5%). - Patients who hospitalized more than 6 weeks had the highest rate of enterococcal isolates (57.8%). - Antimicrobial susceptibility tests using disc diffusion methods revealed that, the isolated enterococci were mostly sensitive to teicoplanin (86%), vancomycin (79.1%) and ampicillinsulbactam (74.4%), on the other hand they were mostly resistant to cefotaxime (93%), ceftazidime (93%), cephalexin (93%), amikacin (88.4%), ciprofloxacin (88.4%),, penicillin G (88.4%), amoxicillin-clavulanic (augmentin)(86%), cefepime (74.4%), streptomycin (74.4%), ampicillin (58.1%) and gentamicin (55.8%). It was found that 9 strains (20.9%) were resistant to vancomycin and 6 strains (14%) resistant to teicoplanin. - When susceptibility of vancomycin-resistant enterococci isolated to other antibiotic by disc diffusion method was done. The results showed that 4 out of 10 VRE strains (40%) were sensitive to teicoplanin and 6 (60%) were resistant to it. Regarding ampicillin-sulbactam 8 strains (80%) were sensitive and 2 (20%) were resistant. Regarding streptomycin 7 strains (70%) were sensitive and 3 (30%) were resistant. 6 (60%) strains were sensitive and 4 (40%) were resistant to both Gentamicin and ampicillin, however results of Cefepime, Amikacin and penicillin G were 1(10%) sensitive and 9 (90%) resistant. All the 10 VRE strains were 100% resistant to amoxicillin-clavulanic (augmentin), ceftazidime, cefotaxime, ciprofloxacin and cephalexin. - Regarding antibiotic resistance pattern of enterococcal isolates 6 major different patterns of antimicrobial resistance (type I, II, III, IV,V and VI) with 32 minor patterns (subtypes) were found among enterococcal isolates. All strains (100%) were multiresistant to antibiotics (they were resistant to at least 7 antimicrobial drugs), type II was the commonest pattern followed by (types III,V,IV,VI and I). - Out of the 43 enterococcal isolates, 19 of the studied enterococci (44.2%) were plasmidless, while 24 strains (55.8%) contained plasmids with variable molecular weight ranging from 1.5 MDa to 42 MDa. 11 plasmids were detected in 24 plasmided enterococci strains. The most commonly encountered plasmids were 6.2 and 2.5MDa (16.3%) followed by 3.5 and 15 MDa (14%). There were 4 isolates had 1.5 MDa, 4 isolates had 1.8 MDa, 4 isolates 4.8 MDa, 4 isolates had 10 MDa, 4 isolates 22 MDa, 4 isolates 35 MDa and 1 isolate had 42 MDa. - Concerning 43 enterococcal isolates, there was consistent correlationship between the plasmid profile and antimicrobial resistant pattern (P value <0.05 significantly positive). - The distribution of enterococcal isolates according to susceptibility to vancomycin and ampicillin by E-test was as follow 33 out of 43 (76.7%) strains were sensitive to vancomycin and 10 out of 43 were resistant (23.3%) [3 (7%) were intermediate resistant and 7 (16.3%) resistant]. Regarding ampicillin 16 out of 43 (37.2%) strains were sensitive and 27 out of 43 (62.8%) strains were resistant. - When we compared the performance of E-test and disc diffusion method, 7(16.3%) of cases that were resistant to vancomycin have been detected by both disc diffusion and Etest with (100%) agreements. However out of 3 (7%) intermediate resistant cases detected by E-test, only 2(4.7%) were detected by disc diffusion method with (66.7%) agreement. The overall agreement between both disc diffusion and E-test was (93.2%). So that E-test is more sensitive than disc diffusion method in detecting vancomycin intermediate resistant strains.