In-vitro susceptibility of 1982 respiratory tract pathogens and 1921 urinary tract pathogens against 19 antimicrobial agents: a Canadian multicentre study. Canadian Antimicrobial Study Group.
(17/1212)
A total of 3903 pathogens from 48 Canadian medical centres were tested against 19 antimicrobial agents. Five agents showed activity against > or = 90% of all 1982 respiratory tract pathogens tested (ciprofloxacin, 90%; cefoperazone, 91%; ticarcillin/clavulanate, 92%; ceftazidime and imipenem, 93% each). Nine agents had > or = 90% activity against Enterobacteriaceae from respiratory tract infection (cefotaxime and ticarcillin/clavulanate, 90% each; aztreonam, ceftizoxime and ceftriaxone, 91% each; ceftazidime, 93%; ciprofloxacin, 97%; imipenem and netilmicin, 98% each). Similarly, five agents had activity against > or = 90% of all 1921 urinary tract pathogens tested (ciprofloxacin and ticarcillin/clavulanate, 90% each; cefoperazone and netilmicin, 91% each; imipenem, 99%). Nine agents had > or = 95% activity against Enterobacteriaceae from urinary tract infection (ciprofloxacin, 95%; cefotetan, 97%; aztreonam, cefotaxime, ceftazidime, ceftizoxime, ceftriaxone and netilmicin, 98% each; imipenem, 99%). Seventeen agents had activity against > or = 95% of Staphylococcus aureus strains. Susceptibility of Pseudomonas aeruginosa isolates ranged from 2% to 91%. (+info)
Retinopathy associated with enterococcus enteropathy in the neonatal rat.
(18/1212)
PURPOSE: Preretinal neovascularization has been previously observed in neonatal rats with spontaneously occurring diarrhea. This neovascularization appears analogous to retinopathy of prematurity (ROP), which occurs in human neonates. A new enterococcus species, designated Enterococcus rattus, has been isolated from the duodenum of these rats. In the present controlled study, the effect of the enteropathy induced by this organism on the retinal vasculature in the neonatal rat was further investigated. METHODS: One hundred fifty newborn Sprague-Dawley rats were randomly assigned to 6 expanded litters (n = 25). On the second day of life, animals were gavaged with either 100 microl of E. rattus suspension (1.0 X 10(7) colony forming units, inoculated group, n = 100 rats) or 100 microl saline (control group, n = 50 rats). All rats were raised in room air and were killed on day 13 of life. Duodenal and blood samples were cultured. The retinal vasculature was assessed using fluorescent microscopy and ADPase staining in a masked manner. Two additional inoculated litters and one control litter were studied for evaluation of arterial blood gases and validation of the grading method for preretinal neovascularization. RESULTS: One hundred percent of rats in the inoculated group developed severe diarrhea and had duodenal cultures positive for E. rattus compared with 0% in the control group. Preretinal neovascularization similar to ROP occurred in 55% of rats in the inoculated group compared with 2% in the control group (P = 0.001). Retinal vascular areas were reduced in the inoculated group (mean +/- SD, 89% +/- 5% versus 96% +/- 2%; P < 0.001). Rats in the inoculated group demonstrated severe growth retardation (final weight, 9.7 +/- 2.2 versus 16.7 +/- 2.7 g, P < 0.001). Inoculated animals also experienced acidosis (pH 7.31 +/- 0.06 versus 7.39 +/- 0.06 control, P = 0.04). CONCLUSIONS: A previously undescribed enterococcal enteropathy was associated with preretinal neovascularization similar to ROP in the neonatal rat. This supports an independent role for factors other than inspired oxygen in the development of ROP. (+info)
Detection of clinically relevant genotypes of vancomycin-resistant enterococci in nosocomial surveillance specimens by PCR.
(19/1212)
This study evaluated a PCR method for the rapid detection of clinically significant genotypes of vancomycin-resistant enterococci (VRE) in nosocomial surveillance specimens. Detection of the vanA and vanB genes by multiplex PCR using 657 specimens that showed presumptive growth of VRE on bile esculin azide agar containing 6 mg of vancomycin/liter was compared to the conventional method. The diagnostic values for the PCR compared to the phenotypic method were as follows: 99.8% specificity, 95.4% sensitivity, 98.8% positive predictive value, and 99.3% negative predictive value. The average cost per test for PCR is $8.26, compared to $9.45 for the phenotypic method. The average turnaround time for detecting a VRE is 48 h for PCR, compared to 96 h for the conventional method. (+info)
Inducible or constitutive expression of resistance in clinical isolates of streptococci and enterococci cross-resistant to erythromycin and lincomycin.
(20/1212)
Thirty-five of 40 clinical isolates of enterococci and streptococci cross-resistant to erythromycin and lincomycin and harbouring erm genes were inducibly resistant to these drugs, suggesting that ribosomal methylation is predominantly inducibly expressed in these bacterial genera. Regulatory regions located upstream of the erm genes of four inducible and three constitutive strains were amplified and sequenced. Expression of constitutive resistance in two strains of Streptococcus pneumoniae and Enterococcus faecalis could be accounted for by a large deletion or a DNA duplication within the regulatory regions, respectively. (+info)
Vancomycin-resistant enterococci in intensive-care hospital settings: transmission dynamics, persistence, and the impact of infection control programs.
(21/1212)
Vancomycin-resistant enterococci (VRE) recently have emerged as a nosocomial pathogen especially in intensive-care units (ICUs) worldwide. Transmission via the hands of health-care workers is an important determinant of spread and persistence in a VRE-endemic ICU. We describe the transmission of nosocomial pathogens by using a micro-epidemiological framework based on the transmission dynamics of vector-borne diseases. By using the concept of a basic reproductive number, R0, defined as the average number of secondary cases generated by one primary case, we show quantitatively how infection control measures such as hand washing, cohorting, and antibiotic restriction affect nosocomial cross-transmission. By using detailed molecular epidemiological surveillance and compliance monitoring, we found that the estimated basic reproductive number for VRE during a study at the Cook County Hospital, Chicago, was approximately 3-4 without infection control and 0.7 when infection control measures were included. The impact of infection control was to reduce the prevalence from a predicted 79% to an observed 36%. Hand washing and staff cohorting are the most powerful control measures although their efficacy depends on the magnitude of R0. Under the circumstances tested, endemicity of VRE was stabilized despite infection control measures, by the constant introduction of colonized patients. Multiple stochastic simulations of the model revealed excellent agreement with observed pattern. In conjunction with detailed microbiological surveillance, a mathematical framework provides a precise template to describe the colonization dynamics of VRE in ICUs and impact of infection control measures. Our analyses suggest that compliance for hand washing significantly in excess of reported levels, or the cohorting of nursing staff, are needed to prevent nosocomial transmission of VRE in endemic settings. (+info)
Proficiency of clinical laboratories in Spain in detecting vancomycin-resistant Enterococcus spp. The Spanish VRE Study Group.
(22/1212)
Studies in a variety of U.S. clinical laboratories have demonstrated difficulty in detecting intermediate and low-level vancomycin-resistant enterococci (VRE). The misclassification of "at least intermediate resistant isolates" as vancomycin susceptible may have both clinical implications and a negative impact on measures to control the spread of VRE. No published study has assessed the ability of clinical laboratories in Europe to detect VRE. So, the apparent low prevalence of VRE in European hospitals may be, in part, secondary to the inability of these laboratories to detect all VRE. In an effort to assess European laboratories' proficiency in detecting VRE, we identified 22 laboratories in Spain and asked them to test four VRE strains and one susceptible enterococcal strain from the Centers for Disease Control and Prevention collection. Each organism was tested by the routine antimicrobial susceptibility testing method used by each laboratory. Overall, VRE were correctly identified in 61 of 88 (69.1%) instances. The accuracy of VRE detection varied with the level of resistance and the antimicrobial susceptibility method. The high-level-resistant strain (Enterococcus faecium; MIC, 512 microg/ml) was accurately detected in 20 of 22 (91. 3%) instances, whereas the intermediate-resistant isolate (Enterococcus gallinarum; MIC, 8 microg/ml) was accurately detected in only 11 of 22 (50%) instances. Classification errors occurred in 27 of 88 (30.9%) instances. Misclassification as vancomycin susceptible was the most common error (16 of 27 [59.3%] instances). Our study shows that the participating Spanish laboratories had an overall acceptable proficiency in detecting VRE but that a substantial proportion of VRE isolates with low or intermediate levels of resistance were not detected. We recommend that studies be conducted to validate laboratory proficiency testing as an important step in the prevention and control of the spread of antimicrobial resistance. (+info)
Potassium/proton antiport system is dispensable for growth of Enterococcus hirae at low pH.
(23/1212)
An energy-dependent K+/H+ antiport system is found in Enterococcus hirae ATCC 9790 cultured in a standard complex medium (Y. Kakinuma, and K. Igarashi, J. Biol. Chem. 263:14166-14170, 1988). We have now found that the activity of this antiport system was totally missing in cells cultured in a defined medium. In this defined medium, E. hirae did not grow well at pH near 9, but grew normally at pH below 7.5. This antiport system is important at high pH but dispensable at lower pH for ion homeostasis of this bacterium. (+info)
Isolation and properties of Enterococcus hirae mutants defective in the potassium/proton antiport system.
(24/1212)
A K+/H+ antiporter regulates cytoplasmic pH in Enterococcus hirae growing at alkaline pH. Mutants defective in this antiport activity were alkaline pH sensitive. One mutant, Pop1, lacked both K+/methylamine exchange at pH 9.5 and concomitant acidification of cytoplasmic pH. Pop1 grew well at pHs below 8 but did not at pHs above 9, conditions under which cytoplasmic pH was not fully acidified. (+info)