f Chlorhexidine and mupirocin are used in health care facilities to eradicate methicillin-resistant Staphylococcus aureus (MRSA) carriage. The objective of this study was to assess the frequency of chlorhexidine and mupirocin resistance in isolates from nares carriers in multiple nursing homes and to examine characteristics associated with resistance. Nasal swab samples were collected from approximately 100 new admissions and 100 current residents in 26 nursing homes in Orange County, CA, from October 2008 to May 2011. MRSA isolates were tested for susceptibility by using broth microdilution, disk diffusion, and Etest; for genetic relatedness using pulsed-field gel electrophoresis; and for qac gene carriage by PCR. Characteristics of the nursing homes and their residents were collected from the Medicare Minimum Data Set and Long-Term Care Focus. A total of 829 MRSA isolates were obtained from swabbing 3,806 residents in 26 nursing homes. All isolates had a chlorhexidine MIC of <4 g/ml. Five (0.6%) isolates harbored the qacA and/or qacB gene loci. Mupirocin resistance was identified in 101 (12%) isolates, with 78 (9%) isolates exhibiting high-level mupirocin resistance (HLMR). HLMR rates per facility ranged from 0 to 31%. None of the isolates with HLMR displayed qacA or qacB, while two isolates carried qacA and exhibited low-level mupirocin resistance. Detection of HLMR was associated with having a multidrug-resistant MRSA isolate (odds ratio [OR], 2.69; P ‫؍‬ 0.004), a history of MRSA (OR, 2.34; P < 0.001), and dependency in activities of daily living (OR, 1.25; P ‫؍‬ 0.004). In some facilities, HLMR was found in nearly one-third of MRSA isolates. These findings may have implications for the increasingly widespread practice of MRSA decolonization using intranasal mupirocin.

A study was conducted to compare three automated systems and the Gram stain for their ability to detect significant bacteriuria. A total of 1,000 urine specimens were evaluated by Autobac MTS (General Diagnostics), AutoMicrobic system (AMS; Vitek Systems, Inc.), and MS-2 (Abbott Laboratories) and compared with a semiquantitative culture plate method. Two hundred thirty-nine (23.9%) specimens had colony counts of >105 colony-forming units (CFU)/ml by the culture plate method (group I). Of these, 204 (85.3%) were positive by Autobac, 198 (82.8%) were positive by AMS, and 179 (74.9%) were positive by MS-2. When pure cultures of diphtheroids, lactobacilli, and viridans streptococci not group D were considered contaminants and therefore excluded, there were 118 specimens containing pure cultures of probable pathogens. The percentage of significant isolates detected was 97.4% (115 of 118) by the Gram stain, 96.6% (114 of 118) by Autobac, and 95.8% (113 of 118) by AMS and MS-2. The average detection time for all organisms was 2.2 h by Autobac, 6.1 h by AMS, and 1.8 h by MS-2; therefore, all three methods were more rapid than the 18-to 24-h standard plate culture method. One hundred sixty-one (16.1%) specimens had colony counts of 104 to 105 CFU/ml (group II). The probable pathogens not detected in this group were two (1.2%) by Autobac and MS-2 and three by AMS (1.9%). The average detection time for group II was 4.2 h by Autobac, 8.9 h by AMS, and 3.8 h by MS-2. Six hundred specimens had colony counts of <104 CFU/ml. Of these, 188 had colony counts equal to 103 and <104 CFU/ml (group III), and 412 cultures were below detectable limits by the standard plate method (group IV). Less than 37 and 15% of groups III and IV, respectively, were detected by instrumentation. Average detection times for groups III and IV were 4.6 and 4.8 h by Autobac, 10 and 11 h by AMS, and 4.2 and 4.4 h by MS-2. The cost of supplies and technical time with Gram stain, Autobac, and MS-2, when used as screening methods, were comparable and considerably less expensive than for the reference method. The AMS was the least expensive system when the cost for identifying probable pathogens was included.

BackgroundMRSA prevalence in nursing homes often exceeds that in hospitals, but reasons for this are not well understood. We sought to measure MRSA burden in a large number of nursing homes and identify facility characteristics associated with high MRSA burden.MethodsWe performed nasal swabs of residents from 26 nursing homes to measure MRSA importation and point prevalence, and estimate transmission. Using nursing home administrative data, we identified facility characteristics associated with MRSA point prevalence and estimated transmission risk in multivariate models.ResultsWe obtained 1,649 admission and 2,111 point prevalence swabs. Mean MRSA point prevalence was 24%, significantly higher than mean MRSA admission prevalence, 16%, (paired t-test, p<0.001), with a mean estimated MRSA transmission risk of 16%.In multivariate models, higher MRSA point prevalence was associated with higher admission prevalence (p=0.005) and higher proportions of residents with indwelling devices (p=0.01). Higher estimated MRSA transmission risk was associated with higher proportions of residents with diabetes (p=0.01) and lower levels of social engagement (p=0.03).ConclusionsMRSA importation was a strong predictor of MRSA prevalence, but MRSA burden and transmission were also associated with nursing homes caring for more residents with chronic illnesses or indwelling devices. Frequent social interaction among residents appeared to be protective of MRSA transmission, suggesting that residents healthy enough to engage in group activities do not incur substantial risks of MRSA from social contact. Identifying characteristics of nursing homes at risk for high MRSA burden and transmission may allow facilities to tailor infection control policies and interventions to mitigate MRSA spread.

We assessed characteristics associated with community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) carriage among residents of 22 nursing homes. Of MRSA-positive swabs, 25% (208/824) were positive for CA-MRSA. Median facility CA-MRSA percentage was 22% (range, 0%–44%). In multivariate models, carriage was associated with age less than 65 years (odds ratio, 1.2; P < .001) and Hispanic ethnicity (odds ratio, 1.2; P = .006). Interventions are needed to target CA-MRSA.

An evaluation was performed on 95 blood cultures positive for Candida spp. to determine the correlation of direct susceptibility testing of fluconazole versus both standardized disk diffusion and MIC methods. For direct testing, an aliquot taken from BD BACTEC Plus and/or BD BACTEC Lytic/10 bottles (Becton Dickinson [BD], Sparks, MD) positive by gram stain for yeast was subcultured to CHROMagar Candida (BD), and a 25-g fluconazole disk (BD) was placed on the plate. The area of growth inhibition surrounding the disk was measured at 24 and 48 h. In addition, a subculture of the isolate was tested by a microdilution MIC using YeastOne (TREK Diagnostics Systems Inc., OH) and disk diffusion (NCCLS M44-A) using a standardized inoculum plated onto CHROMagar Candida as well as Mueller-Hinton agar to which 2% glucose and 0.5 g/ ml methylene blue dye was added (MH-GMB). The categorical interpretation derived from the MIC was used as the reference to which the disk diffusion results were compared. There were a total of 41 Candida albicans, 23 Candida glabrata, 20 Candida parapsilosis, 9 Candida tropicalis, and 1 each of Candida krusei and Candida lusitaniae tested. At 24 h there was full agreement among the methods for all C. albicans, C. tropicalis, C. lusitaniae, and C. krusei isolates. For the C. parapsilosis isolates at 24 h there was one very major discrepancy using the direct CHROMagar and one major error with the standardized MH-GMB. The majority of the errors were seen at 24 h with the C. glabrata isolates. Of the 23 C. glabrata isolates at 24 h by direct CHROMagar, there were 10 minor and 1 very major error; by MH-GMB there were 12 minor and 2 very major errors; and by standardized CHROMagar Candida there were 13 minor and 2 major errors. There were no very major errors with C. glabrata when all plates were read at 48 h. At 24 h by the direct and standardized CHROMagar the majority of C. glabrata isolates were more resistant, whereas by MH-GMB they were more susceptible than the reference MIC interpretation. In summary, subculturing yeast directly from blood cultures onto CHROMagar to which a fluconazole disk has been added may provide a presumptive identification at 24 h and, with the exception of C. glabrata, was able to predict the susceptibility to fluconazole with the majority of Candida isolates examined in this evaluation.Over the past decade there has been more interest and subsequently progress in developing reliable methods for the susceptibility testing of yeast. In particular, testing Candida species against azole antifungal agents has provided valuable information for treatment of patients with invasive yeast infections. However, even with the advent of standardized guidelines for microdilution methods, testing is not readily available for a majority of laboratories due to the expense and labor that are inherent in the method (5, 6). Recently, guidelines for testing by disk diffusion have been published (7). This method utilizes a medium and a procedure that are familiar to the vast majority of labora...