Post-operative endophthalmitis: Antibiogram & genetic relatedness between Pseudomonas aeruginosa isolates from patients & phacoemulsifiers.

Background & objectives: Though not frequently but there are reports showing phacoemulsifiers as a potent source of infection in post-operative cases of endophthalmitis. This study was carried out to find antibiogram and genetic relatedness between Pseudomonas aeruginosa isolates from a post-cataract surgery endophthalmitis outbreak (3 patients) and internal tubings of 5 phacoemulsifiers. Methods: In vitro antimicrobial sensitivity patterns of the 8 bacterial isolates were observed. Genetic analysis of the bacterial isolates was done using random amplification of polymorphic DNA (RAPD) assay and PCR ribotyping. The resulting DNA band patterns were examined visually and by computer assisted analysis using unweighted pair group method. Results: The three P. aeruginosa patient isolates were found to be different from the five phacoemulsifier isolates in sensitivity towards 3 antibiotics and by genetic analysis (33 and 44% homology by RAPD assay and PCR ribotyping). Two of the patient isolates shared 100 per cent genetic homology by RAPD assay and another pair shared 100 per cent homology by PCR ribotyping. The five isolates from phacoemulsifiers did not share significant genetic homology. There was significant genetic variation between bacterial isolates from patients and phaco emulsifiers. Interpretation & conclusion: Though the three P. aeruginosa isolates obtained from the patients were phenotypically similar and genetically close, they differed from the phaco-machine isolates both genetically, and in their antibiogram profile. However, the five phacoemulsifier isolates were genetically diverse though they shared the same antibiogram profile. Therefore the Ringer’s lactate from phacomachines could not be conclusively proven to be the source of infection.

Outbreak of Nosocomial Urinary Tract Infections caused by Multidrug-Resistant Pseudomonas aeruginosa / 병원감염관리

BACKGROUND: Nosocomial urinary tract infection (UTI) accounts for 35% of the nosocomial infection and 80-90% of them are associated with urethral catheters. Recently, we experienced an outbreak of nosocomial UTI caused by multidrug-resistant Pseudomonas aeruginosa in neurosurgical intensive care unit (NSICU). METHODS: We investigated clinical records of the patients and observed the methods of care of urethral catheters in NSICU. Identification of P. aeruginose was done by API NE (API system; bioMerieux, France) and antibiotic susceptibility tests were done by disk diffusion method. Random Amplification of Polymorphic DNA (RAPD) assay was used as a genotyping method. RESULTS: Between November 1997 and January 1998, 11 P. aeruginosa strains were isolated from the urine of 11 patients hospitalized in NSICU of Kangnam St. Mary's Hospital. Routine regular bladder irrigation, and emptying urine with common urinal had been done falsely. Antibiogram of the isolates showed resistance to multiple antibiotics including imipenem, gentamicin. amikacin, piperacillin, ciprofloxacin, ceftazidime, and cefoperazone/sulbactam. RAPD of the outbreak strains showed clonal relatedness, which was different from those of other clinical strains, We instructed all the health care workers to stop bladder Irrigation, and to use the separate urinals for each patient. Thereafter, no further case of P. aeruginosa UTI has occurred. CONCLUSION: An outbreak of UTI, caused by a single clone of P. aeruginosa, was confirmed by RAPD and was eradicated after correction of false practice on care-of urinary catheter.