Pseudomonas aeruginosa clonal dissemination in adult intensive care unit in Benha university hospital

ABSTRACT

To investigate the sources and spread of Pseudomonas in the Adult Intensive Care Unit [ICU], Benha University Hospital, 60 Pseudomonas aeruginosa strains were isolated from patients, staff and environmental samples and were typed using the randomly amplified polymorphic DNA [RAPD] and the enterobacterial repetitive intergenic consensus [ERIC] polymerase chain reaction [PCR] methods. Testing for extended spectrum beta lactamses and metallo-beta-lactamase [MBL] production was also performed. 50% of patient samples were positive for Pseudomonas aeruginosa. 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. MBL production was highest in patient strains [92%], less in environmental strains [19%] and was not detected in staff hand samples. The difference in MBL distribution between patient and environmental/stuff samples was statistically significant [P < 0.00 I]. All the Pseudomonas aeruginosa isolates were typable by both RAPD and ERIC-PCR methods. Seven RPAD patterns [RAPDI-RAPDVII] and eight ERIC patterns were obtained 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]. Water-tap and suction apparatus played a central role in the spread of Pseudomonas aeruginosa in the ICU. Both water-tap and suction apparatus were epidemiologically linked and both had been epidemiologically linked to patients. Water-top was molecularly linked to staff hands and artificial ventilation fluid reservoir. Suction apparatus was linked to medical trays and stethoscope. 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