Abstract Objectives: To assess the prevalence of high-level gentamicin-resistant enterococcus (HGRE) colonization, transmission patterns, and spectrum of illness among residents of a long-term care facility. Design: Monthly surveillance for HGRE colonization of wounds, rectum, and perineum over a 1-year period. Setting: A Veterans Affairs long-term care facility attached to an acute-care facility. Patients: All 341 patients in the facility during the observation period. Results: Over the 1-year period, 120 patients (35.2%) were colonized with HGRE at least once, with an overall monthly colonization rate of 20± 1.5%. HGRE were isolated from rectum (12.8%), wounds (11.7%), and perineum (9.3%). Patients with the poorest functional status had the highest rate of colonization (P<0.0005). HGRE-colonized patients were more likely to be colonized with methicillin-resistant Staphylococcus aureus (51% versus 25%; P<0.0005). Seventy-four patients (21.7%) were colonized at admission or at the start of the study. Another 46 patients (13.5%) acquired HGRE during the study, including 36 who acquired HGRE while in the long-term care facility and 10 who were positive when transferred back from the acute-care hospital. Based on plasmid profiles, only two patients appeared to have isolates similar to those of current or previous roommates. Carriage of HGRE was transient in most cases. Only 20 patients were colonized for 4 or more months, and those patients usually carried different strains intermittently. Infections were infrequent, occurring in only 4.1% of total patients. Conclusions: In our long-term care facility, HGRE were endemic, and new acquisition of HGRE occurred frequently. However, only two patients had evidence of acquisition from a roommate, suggesting that cross-infection from a roommate was not a major route of spread of HGRE.
A microdilution assay using Alamar Blue, a colorimetric indicator, was compared with the NCCLS macrodilution broth assay for voriconazole, fluconazole, and itraconazole against Candida albicans, Candida glabrata, and Candida krusei. Concordance (+/- 2 dilutions) between the two methods was highest for voriconazole (98.3%), and for fluconazole and itraconazole it was 94.3 and 95.4%, respectively. Twenty-six of 32 (81.2%) discordant readings (> or = 3 dilutions different) were noted in C. glabrata isolates, and all but two isolates showing discordance had higher minimum inhibitory concentration readings with the colorimetric method.
Fluconazole and itraconazole MICs were determined by both the standard macrodilution method of the National Committee for Clinical Laboratory Standards and a colorimetric broth microdilution method for 140 isolates of Torulopsis (Candida) glabrata obtained over a 15-year period. Using the method of the National Committee for Clinical Laboratory Standards the MICs at which 90% of isolates are inhibited (MIC50) for all isolates were 32 and 1.6 micrograms/ml for fluconazole and itraconazole, respectively. For fluconazole, the MIC90 rose from 16 to > 64 micrograms/ml when the MIC90s for isolates collected from July 1980 to June 1991 were compared with those for isolates collected from July 1991 to March 1995. For itraconazole, the MIC90s for isolates from the same time periods were 0.8 and 3.2 micrograms/ml, respectively. Although for isolates from some non-human immunodeficiency virus-infected patients the MICs rose, most of the high MICs were found for isolates from human immunodeficiency virus-infected patients who had been extensively treated with azole drugs for thrush. The colorimetric method yielded endpoints that were more definitive; concordances within 2 dilutions for the two methods were 87% for fluconazole and 86% for itraconazole.
Fourteen mupirocin-resistant Staphylococcus aureus strains were isolated over 18 months; 12 exhibited low-level resistance, while two showed high-level resistance. Highly mupirocin-resistant strains contained a large plasmid which transferred mupirocin resistance to other S. aureus strains and to Staphylococcus epidermidis. This plasmid and pAM899-1, a self-transferable gentamicin resistance plasmid, have molecular and biologic similarities.
For 212 oropharyngeal isolates of Candida albicans, the fluconazole MICs for 50 and 90% of strains tested were 0.5 and 16 micrograms/ml, respectively, and those of itraconazole were 0.05 and 0.2 micrograms/ml, respectively. Of 16 isolates for which fluconazole MICs were > 64 micrograms/ml, itraconazole MICs for 14 were < or = 0.8 micrograms/ml and for 2 were > 6.4 micrograms/ml. Most fluconazole-resistant strains remained susceptible to itraconazole; whether itraconazole will prove effective for refractory thrush remains to be shown.
