Problem of antimicrobial resistance of fecal aerobic gram-negative bacilli in the elderly.

In this study, we assessed the magnitude of risk (odds ratio [OR]) of patients being colonized with fecal aerobic gram-negative bacilli in two geriatric hospitals compared with the community, and we associated the use of antimicrobial agents with bacterial resistance. One fecal sample was collected from each of 341 patients, aged 60 years or older, during the hospital stay or when visiting the outpatient service. Samples were collected in 1988 and 1993 to 1994. The aerobic gram-negative bacilli from all samples were examined for resistance to seven antimicrobials by a replica plating method. The long-term-hospitalized patients had a significantly higher risk of being colonized with bacilli resistant to ampicillin (OR, 14.3; 95% confidence interval [95% CI], 6.0 to 34.1), cefuroxime (OR, 7.5; 95% CI, 2.7 to 20.8), trimethoprim (ORs, 22.3; 95% CI, 8.6 to 57.8), and tetracycline (OR, 5.2; 95% CI, 2.4 to 10.9) than the outpatients. The respective ORs among the short-term-hospitalized patients compared with the outpatients were 4.0 (95% CI, 1.9 to 8.4), 7.5 (95% CI, 2.7 to 20.8), 5.5 (95% CI, 2 to 14), and 2.0 (95% CI, 1 to 4). In 1993 to 1994 compared with 1988, in both hospitals there was a significantly increased risk of colonization by bacilli resistant to ampicillin (OR, 3.1; 95% CI, 1.9 to 5.1), cefuroxime (OR, 3.8; 95% CI, 2.1 to 6.7), and tetracycline (OR, 1.6; 95% CI, 1.0 to 2.5). However, the total use of antimicrobial agents increased only among the patients of the short-term-care hospital.

Increase of antimicrobial resistance of faecal aerobic gram-negative bacteria in a geriatric hospital.

Antimicrobial resistance of faecal aerobic Gram-negative bacteria to eight different antimicrobials was determined by a velvet replica-plating method in 1988 and 1933. Faecal samples were taken from 131 geriatric inpatients in the Turku City Hospital with a hospitalization of more than 7 days. From 1987 to 1992 the use of first and second generation cephalosporins and ciprofloxacin increased from 3.32 defined daily doses (DDD) per bed to 24.25 DDD/bed and from 0.63 DDD/Bed to 28.11 DDD/bed, respectively. A statistically significant increase was observed in the frequency of samples resistant (with >= 1% of resistant colonies) to cefuroxime (p = 0.0004) and ceftazidime (p = 0.037) in patients who received antimicrobial therapy and to ampicillin (p = 0.046) in patients who had not received antimicrobial therapy. In addition, despite the decreased use of sulphonamides and trimethoprim (from 17.11 DDD/bed to 5.54 DDD/bed) no significant changes in the frequency of resistant faecal samples were observed. Use of ciprofloxacin has been found to cure resistance plasmids from bacteria in vitro. However, despite the increased use of ciprofloxacin, no decrease in faecal bacteria resistant to any of the other antimicrobials (i.e. trimethoprim) studied was observed.

Epidemiology of plasmid-mediated beta-lactamases in enterobacteria Swedish neonatal wards and relation to antimicrobial therapy.

TEM-1, OXA-1, SHV-1, and related beta-lactamases in fecal isolates from 953 infants in 22 Swedish neonatal intensive care units were studied by DNA hybridization. TEM-1- and OXA-1-positive isolates were always Escherichia coli and represented 86 and 8%, respectively, of the ampicillin-resistant isolates of this species. SHV-1 was found in 16% of the Klebsiella sp. (mainly Klebsiella pneumoniae) isolates. TEM-1 and SHV-1 occurred in 14 and 16 units and in up to 64 and 26% of the neonates, respectively. On average, two to four different biochemical phenotypes per species per ward were positive for each beta-lactamase. All but 1 of the 33 E. coli phenotypes found to be TEM-1 positive were uniformly positive for the beta-lactamase gene, whereas some of the phenotypes found to be positive for OXA-1 (2 of 3) and SHV-1 (6 of 70) were occasionally negative for the respective genes. The occurrence of the three beta-lactamases studied tended to be associated with local ampicillin usage (correlation coefficient, 0.31 to 0.39; P greater than 0.05). Of the neonates receiving ampicillin, 30% carried TEM-1-positive E. coli, compared with 13% for cephalosporin-treated neonates and 15% for untreated neonates (P less than or equal to 0.001). The corresponding rates for SHV-1 in Klebsiella spp. were 18, 13, and 9% (P less than or equal to 0.01). Ampicillin is thus a significant risk factor for the maintenance of the most prevalent gram-negative plasmid-mediated beta-lactamases in hospitalized neonates.

Outbreak of diarrhoea due to Escherichia coli O111:B4 in schoolchildren and adults: association of Vi antigen-like reactivity.

During six days in November, 1987, 611 pupils (age range 7-19 years) and 39 adults (23-57) at a school complex in southern Finland had diarrhoea due to Escherichia coli O111:B4. Diarrhoea developed in 137 other household members during the two weeks after the school outbreak. The source of the organism remains unknown. The outbreak strains, when incubated at 22 degrees C or exposed to ampicillin, lost the lipopolysaccharide O antigen and began to react with antisera against Salmonella typhi Vi antigen. The Vi antigen-like reactivity increased the adherence of the organisms to Hep-2 cells. These results indicate that E coli O111:B4, and possibly other enteropathogenic E coli strains, should be considered in the diagnosis of all diarrhoea cases and not only in infantile diarrhoea. Expression of Vi antigen in E coli may play a part in virulence by enhancing adherence to the intestinal epithelium.