الفهرس 
ACKNOWLEDGMENTOnly 14 pages are availabe for public view
 |  | from | 16 |  |  |
| | | from | 16 | | |
Abstract
Summary
Enterococci are common inhabitants of the GI tract of humans. Enterococci
have emerged as one of the leading cause of nosocomial infections, and recently have
been persisting clinical problem globally due to their resistance to antibiotics. Also, it
was likely that other virulence determinants were involved in the success of these
microorganisms in the hospital setting.
Isolates were diagnosed by culture and biochemical reactions. The antibiotic
sensitivity pattern was determined by Kirby-Bauer disc diffusion method.
Vancomycin resistance was detected phenotypically by agar screen method and
genotypically by detection of vanA/B. The production of cytolysin, gelatinase and
biofilm were detected phenotypically and genotypically by PCR of (cylA, gelE, esp
and vanA/B genes).
We undertook this study to determine the prevalence of enterococci causing
nosocomial infections, intestinal carriage and environmental contamination in the
ICUs of Assiut University Hospitals. Also, to determine some virulence factors and
the antibiotic resistance of enterococci isolates. In this study, 30 clinical isolates, 10
environmental and 10 commensal isolates were included.
Considerable percentage of enterococci was recorded in nosocomial infections
in the ICUs of Assiut University Hospitals (10.5%). The highest percentages of
contamination by enterococci were recorded in the chest ICU (56%). Also, the
highest percentage of enterococci was recorded in the lower respiratory tract
infections samples (86.7%). The most prevalent species of enterococci were
E.casseliflavus (36%), E.gallinarum (32%) and E.faecalis (30%).
High prevalence of vancomycin resistance was detected, in commensal
isolates (70%), for environmental (50%) and clinical isolates (40%). Also, it was
found that artificial feeding and immunodeficiency were the important risk factors for
vancomycin resistance. Phenotypic detection of virulence factors revealed that 12%
of the isolates were β haemolytic, 48% of the isolates were positive for gelatin
hydrolysis. Summary
91
Different results were reported in biofilm detection by three methods;
however the microtiter plate method showed the highest percentage of detection of
biofilm among all isolated species. Regarding the antibiotics resistance, enterococci
were completely resistant to most antibiotics tested. Also, various percentages of
resistance were reported for amoxicillin & clavulanic acid (95%), cefazolin (98%),
norfloxacin (96%), lomefloxacin (98%), gentamicin (98%), oxytetracycline (64%),
tiecoplanin (40%), tetracycline (58%) and chloramephincol (56%). The least
resistance was reported for linezolid (2%). The best method for detection of
vancomycin resistance was agar screening method.
For genotypic detection of virulence genes, 62% for gelE gene, 12% for esp
gene, 12% for vanB gene and 2% for vanA gene. cylA gene was absent from all
isolates. Positive correlation between genotypic and phenotypic method for detection
of gelatinase and biofilm (P=0.001, 0.044 respectively). In addition, significant
correlation was recorded between antibiotic resistance biofilm formations. For
vancomycin resistance by agar screening method, strong correlation with detection of
vanB gene was reported (P=0.006). We conclude that enterococci especially
vancomycin resistant caused a significant percentage of health care acquired
infections, intestinal carriage and environmental contamination in the ICUs of Assiut
University Hospitals. Isolates were highly resistant to most antimicrobials. A
considerable percentage produced cytolysin, gelatinase and biofilm.