Vancomycin-resistant Enterococcus faecium outbreak in a nephrology ward

In April 2000, an outbreak of vancomycin-resistant Enterococcus faecium (VRE) was discovered in an internal medicine/nephrology and dialysis ward of the Eemland Hospital, Amersfoort, the Netherlands. Although enterococci are considered relatively non-virulent, VRE are resistant to almost all commercially available antibiotics. Surveillance cultures were obtained from all patients at the ward, all patients visiting the dialysis ward and the environment of patients. VRE were determined and clustering of strains was analysed using molecular genotyping. In all, 12 patients were colonized with the outbreak strain. Transmission of VRE usually occurs via the hands of health care workers. The ward was closed for new admissions, patients were divided in cohorts of colonized and non-colonized patients, and rooms were disinfected after patient discharge. Infection control measures (such as handwashing and use of gloves and gowns) were enforced and prescriptions of vancomycin and cephalosporins were reduced. With these measures the outbreak could be controlled. Epidemiological analysis demonstrated that earlier admission and previous use of ciprofloxacin, amoxicillin and amoxicillin-clavulanic acid were risk factors for colonization. A nearby hospital was a possible source of this outbreak.

Free radical production by antibiotic-killed bacteria in the guinea pig middle ear.

OBJECTIVES: Oxygen free radicals are implicated in the pathogenesis of otitis media Recent investigations with animal models have demonstrated that free radical-mediated damage of the middle ear mucosa, measured as lipid hydroperoxide, occurs when the middle ear cavity is inoculated with Streptococcus pneumoniae. The present study was conducted to examine the effect of antibiotics on free radical-mediated damage in pneumococcal acute otitis media. STUDY DESIGN: Animal model of acute otitis media. METHODS: Seventy-eight guinea pigs underwent bilateral middle ear inoculation with 100 microl of 1) sterile saline as a control, 2) 50 microg/mL amoxicillin, 3) 10(7) colony forming units (CFU)/mL Streptococcus pneumoniae killed with 50 microg/mL amoxicillin, or 4) 10(7) CFU/mL S. pneumoniae. Animals were killed on postoperative day 1 or 5, and the middle ear mucosa was examined for lipid peroxidation as evidence of free radical damage. RESULTS: Mucosal lipid hydroperoxide was significantly elevated compared with control subjects on day 1 in both the antibiotic-killed S. pneumoniae group and the S. pneumoniae-infected group. On day 5, the S. pneumoniae-infected mucosa had significantly higher lipid hydroperoxide levels compared with the antibiotic-killed group and the control subjects. Histological studies confirmed mucosal edema and the presence of inflammatory cells in the infected groups. CONCLUSIONS: Antibiotic-killed bacteria seem to produce free radical-mediated damage to the middle ear mucosa in the early phase of acute otitis media. The clinical implication of this study is that free radical damage to the middle ear mucosa may occur in otitis media despite appropriate antibiotic therapy.

The effects of amoxicillin therapy on skin flora in infants.

In order to determine the effect of amoxicillin therapy on the perineal skin microbial flora in infants, we took quantitative bacterial and fungal cultures of perineal and sternal areas from 25 infants treated with amoxicillin (40 mg/kg/day) for 10 days. Specimens were obtained prior to therapy, within 3 days of conclusion of therapy, and 14-16 days later. Immediately following therapy, a decline in the number of bacterial isolates occurred on both the perineum (89 to 47) and sternum (84 to 39). The greatest decline occurred in the number of anaerobic bacteria (mostly Peptostreptococcus spp. and Propionibacterium acnes). Other organisms that were less often isolated were aerobic streptococci and Staphylococcus epidermidis. The number of Candida albicans isolates increased from 3 to 11 (p < 0.05) on the perineum, and 1 to 7 (p < 0.025) on the sternum. Four of the infants developed diaper dermatitis. The density of C. albicans increased more than 14-fold following amoxicillin therapy. Cultures done 14-16 days after cessation of therapy revealed an increase in the number of bacterial isolates on the perineum (47 to 72) and on the sternum (39 to 61) and a decline in recovery of C. albicans. This study demonstrates the effects of amoxicillin on the ecology of skin microbial flora in infants-a decrease in the number of bacterial isolates and an increase in recovery of C. albicans.

Screening method for identification of beta-lactams in bovine urine by use of liquid chromatography and a microbial inhibition test.

OBJECTIVE: To develop a multiple-residue screening method for the detection of beta-lactams in bovine urine. ANIMALS: 6 clinically normal Holstein cows and 6 calves. PROCEDURE: Pooled urine obtained from cows was used as a negative-control sample or spiked with varying concentrations of 6 beta-lactam antibiotics. Urine samples were prepared for liquid chromatography by diluting 1 ml of urine with 9 ml of 0.01M KH2PO4, 0.01 M Na2PO4, and filtering. Filtrate (2,000 ml) was eluted with a mobile phase in a gradient program. A fraction corresponding to each beta-lactam of interest was collected and evaporated to < 1 ml, and water then was added to achieve a 1 ml volume. The collected fraction was tested, using a microbial inhibition test. Then, calves were fed milk spiked with a mixture of 5 beta-lactam antibiotics at a concentration 40X the FDA tolerance in milk. Three hours following the feeding, urine samples were obtained from the calves and tested, as described for the urine samples for the cows. RESULTS: The lowest concentrations of amoxicillin, ampicillin, cephapirin, cloxacillin, desfuroylceftiofurcysteine, and penicillin G that were consistently detected in urine were 100, 10, 100, 250, 1,000, and 10 ng/ml, respectively. Amoxicillin, ampicillin, cephapirin, cloxacillin, desacetylcephapirin, and penicillin G were detected in urine samples of 6/6, 5/6, 0/6, 6/6, 2/6, and 3/6 calves respectively, fed antibiotic-spiked milk. CONCLUSIONS AND CLINICAL RELEVANCE: The integrated method described can be used to detect or identify beta-lactam antibiotics in bovine urine. This method can be used to test cattle for beta-lactam residues.