الفهرس 
PseudomonasOnly 14 pages are availabe for public view
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Abstract
Pseudomonas aeruginosa is a common pathogen that causes nosocomial infections in intensive care units. Resistant P. aeruginosa is an emerging threat to patients. With the rising spread of antibiotic-resistant organisms, clinical laboratories must focus more and more on the epidemiology of hospital-acquired infections. Strain typing is an extremely useful tool in tracking the spread of nosocomial infections.
In the present study we try to elucidate the epidemiology of Pseudomonas aeruginosa in the adult ICU. Several patient and environmental samples from Benha University adult ICU have been typed using RAPD and ERIC-PCR to investigate possible relationships. Antibiogram was performed as a typing method and the antibiotic susceptibility tests included testing for extended spectrum beta lactamses and metallo-β-lactamase production.
The result of the study showed the following:
50% of patient samples were positive for Pseudomonas aeruginosa, and the highest rate of Pseudomonas isolation was from sputum samples (62%).
33% of the environmental samples were positive for Pseudomonas aeruginosa. Highest frequencies of Pseudomonas isolation were from Ambu bags (100%), stethoscope (100%), suction apparatus tubing (100%), water tap/sink (80%) and floor (75%).
13% of staff hand samples were positive for Pseudomonas aeruginosa.
Metallo beta lactamase production was tested for by Meropenem-EDTA double-disk synergy test and E-Test MBL, both tests gave equivalent results. MBL production was highest in patient strains (92%), less in environmental strains (19%) and was not detected in staff hand strains. The difference in MBL distribution between patient and environmental/staff samples was statistically significant (P < 0.001).
There was clear difference in antibiotic resistance between MBL producing Pseudomonas and non MBL producing Pseudomonas. The former was much more resistant to all antibiotics tested. The only exception was CT (colistin) to which nearly all Pseudomonas strains (both MBL and non-MBL producing strains) were sensitive.
The isolated Pseudomonas aeruginosa strains showed 7 antibiotic sensitivity patterns that were designated A1-A7. The antibiotic sensitivity patterns range from pattern A1 which is sensitive to all tested antibiotics to pattern A7 which is resistant to all tested antibiotics except colistin.
All the Pseudomonas aeruginosa isolates were typable by RAPD method. Seven RAPD patterns (RAPDI-RAPDVII) were obtained, consisting of 2 to 7 bands ranging from 200 bp to 2000 bp.
ERIC-PCR yielded 1 to 5 amplification bands. The size of amplified DNA bands ranged from 75 bp to 7000 bp. All the 60 isolates were typable by this method. Eight ERIC patterns were obtained (ERICI-ERICVIII).
ERIC typing method gave higher discriminatory index (0.7955) than RAPD (0.7706), still the combination of both gave the highest discriminatory index (0.7977). Antibiogram gave the lowest discriminatory index (0.7232).
Water-tap and suction apparatus played a central role in the spread of Pseudomonas aeruginosa in the ICU. Water-tap had had established molecular epidemiological relations with staff hands and artificial ventilation fluid reservoir. Suction apparatus was epidemiologically linked to medical trays and stethoscope.
Both water-tap and suction apparatus were epidemiologically linked and both had been epidemiologically linked to patients.
Epidemiological linkage has been also proved between patients and artificial ventilation tubing.
The patient MBL-producing strains were epidemiologically linked to water tap and suction apparatus tubing.