Bacteria isolated from urine and their susceptibility in elderly patients

Objective - The susceptibility and incidence of Gram+ and Gram- bacteria is olated from urine in elderly patients was studied. Method - From January 1998 to December 1998, 2,062 bacterial strains were c ollected from 2,565 urine samples in 899 patients (mean age 84.8 +/- 0.6 ye ars, range 50.5 to 108.4 years). Results - We found: Escherichia coli (38.7 +/- 2.1%), Enterococcus faecalis (111.5 +/- 1.4%), Proteus mirabilis (11.1 +/- 1.4%), Pseudomonas aeruginos a (9.9 +/- 1.3%), Klebsiella pneumonia (5.7 +/- 1%), and Staphylococcus aur eus (5.2 +/- 1%). Those figures correspond respectively to 1.62 +/- 0.11, 0 .48 +/- 0.06, 0.47 +/- 0.06, 0.41 +/- 0.06, 0.24 +/- 0.04, 0.22 +/- 0.04 in cidence density per 1,000 patient days. Only 42.6 +/- 3.4% of Escherichia c oil strains and 28.7 +/- 5.8% of Proteus mirabills strains were susceptible to amoxicillin. Clavulanic acid completely or partially restored the activ ity of amoxicillin in 84.6 +/- 2.5% of Escherichia coli strains, 90.4- +/- 3.8% of Proteus mirabilis strains, and 90.5 +/- 5.3% of Klebsiella pneumoni a strains. Third generation cephalosporins and aminoglycosides remained act ive on Enterobacteria whereas cotrimoxazole and nalidixic acid were irregul arly active. Imipenem, ceftazidime, and ciprofloxacin inhibited respectivel y 78.4 +/- 5.6%, 89.7 +/- 4.2%, and 44.6 +/- 6.8% of Pseudomonas aeruginosa strains. Only 12.1 +/- 6.2% of Staphylococcus aureus strains were suscepti ble to oxacillin. However, cotrimoxazole inactivated 96.3% of Staphylococcu s aureus strains and gentamicin 74.8 +/- 8.2%. Ampicillin was active in Ent erococcus faecalis. Conclusion - Sampling urine for culture should be performed before choosing an antimicrobial therapy for UTI in elderly patients. (C) 2001 Editions sc ientifiques et medicales Elsevier SAS.