Contamination of health-care workers' hands with Escherichia coli and Klebsiella species after routine patient care: a prospective observational study.

OBJECTIVE: To compare the frequency of health-care worker (HCW) hand contamination by Escherichia coli versus Klebsiella species after patient care and to determine activities associated with contamination. METHODS: We conducted a prospective observational study at two tertiary-care centres. We observed HCWs caring for patients colonized/infected with E. coli or Klebsiella. HCW hands were cultured before room entry and after patient care. Contamination was defined as detecting E. coli or Klebsiella on HCW hands. Risk factors for contamination were analysed using logistic regression. Patient-to-HCW transmission was confirmed by pulsed-field gel electrophoresis (PFGE). RESULTS: We performed 466 HCW observations: 290 from patients with E. coli, 149 with Klebsiella, and 27 with both species. Eighty-seven per cent of observations (404/464) occurred in patients who had received chlorhexidine bathing within 2 days. HCW hand contamination rates were similar between E. coli (6.2%; 18/290) and Klebsiella (7.4%; 11/149) (p 0.6). High-risk activities independently associated with contamination were toilet assistance (OR 9.34; 95% CI 3.10-28.16), contact with moist secretions (OR 6.93; 95% CI 2.82-17.00), and hygiene/bed-bathing (OR 3.80; 95% CI 1.48-9.80). PFGE identified identical/closely related isolates in the patient and HCW hands in 100% (18/18) of E. coli and 54.5% (6/11) of Klebsiella observations. CONCLUSIONS: We did not find a difference in HCW hand contamination rates between E. coli and Klebsiella after patient care. Hand hygiene should be reinforced after high-risk activities. Discrepancies in matching patient and HCW hand isolates occurred more frequently for Klebsiella than for E. coli; differences in species-level transmission dynamics might exist.

Validation of 24-hour posaconazole and voriconazole MIC readings versus the CLSI 48-hour broth microdilution reference method: application of epidemiological cutoff values to results from a global Candida antifungal surveillance program.

We performed 24- and 48-h MIC determinations of posaconazole and voriconazole against more than 16,000 clinical isolates of Candida species. By using the 24- and 48-h epidemiological cutoff values (ECVs), the categorical agreement between the 24-h and reference 48-h broth microdilution results ranged from 97.1% (C. parapsilosis and voriconazole) to 99.8% (C. krusei and voriconazole), with 0.0 to 2.9% very major discrepancies (VMD). The essential agreement (within 2 log(2) dilutions) between the 24- and 48-h results was 99.6% for both posaconazole and voriconazole. The MIC results obtained for both posaconazole and voriconazole after only 24 h of incubation may be used to determine the susceptibilities of Candida spp. to these important antifungal agents. The applications of ECVs to this large collection of Candida isolates suggests the potential to develop 24-h species-specific clinical breakpoints for both posaconazole and voriconazole.

Comparison of the broth microdilution (BMD) method of the European Committee on Antimicrobial Susceptibility Testing with the 24-hour CLSI BMD method for testing susceptibility of Candida species to fluconazole, posaconazole, and voriconazole by use of epidemiological cutoff values.

The antifungal broth microdilution (BMD) method of the European Committee on Antimicrobial Susceptibility Testing (EUCAST) was compared with CLSI BMD method M27-A3 for fluconazole, posaconazole, and voriconazole susceptibility testing of 1,056 isolates of Candida. The isolates were obtained in 2009 from more than 60 centers worldwide and included 560 isolates of C. albicans, 175 of C. glabrata, 162 of C. parapsilosis, 124 of C. tropicalis, and 35 of C. krusei. The overall essential agreement (EA) between EUCAST and CLSI results ranged from 96.9% (voriconazole) to 98.6% (fluconazole). The categorical agreement (CA) between methods and species of Candida was assessed using previously determined epidemiological cutoff values (ECVs). The ECVs (expressed as µg/ml) for fluconazole, posaconazole, and voriconazole, respectively, were as follows: 0.12, 0.06, and 0.03 for C. albicans; 32, 2, and 0.5 for C. glabrata; 2, 0.25, and 0.12 for C. parapsilosis; 2, 0.12, and 0.06 for C. tropicalis; 64, 0.5, and 0.5 for C. krusei. Excellent CA was observed for all comparisons between the EUCAST and CLSI results for fluconazole, posaconazole, and voriconazole, respectively, for each species: 98.9%, 93.6%, and 98.6% for C. albicans; 96.0%, 98.9%, and 93.7% for C. glabrata; 90.8%, 98.1%, and 98.1% for C. parapsilosis; 99.2%, 99.2%, and 96.8% for C. tropicalis; 97.1%, 97.1%, and 97.1% for C. krusei. We demonstrate high levels of EA and CA between the CLSI and EUCAST BMD methods for testing of triazoles against Candida when the MICs were determined after 24 h and ECVs were used to differentiate wild-type (WT) from non-WT strains. These results provide additional data in favor of the harmonization of these two methods.

Comparison of the broth microdilution methods of the European Committee on Antimicrobial Susceptibility Testing and the Clinical and Laboratory Standards Institute for testing itraconazole, posaconazole, and voriconazole against Aspergillus isolates.

We compared EUCAST and CLSI antifungal susceptibility testing methods for itraconazole, posaconazole, and voriconazole by testing 245 Aspergillus clinical isolates. The essential agreement (EA) between methods was excellent: 100% (itraconazole), 98.4% (posaconazole), and 99.6% (voriconazole) assessing EA at ±2 dilutions and 99.6% (itraconazole), 87.7% (posaconazole), and 96.3% (voriconazole) at ±1 dilution.

Wild-type MIC distributions and epidemiological cutoff values for posaconazole and voriconazole and Candida spp. as determined by 24-hour CLSI broth microdilution.

We tested 16,191 strains of Candida against posaconazole and voriconazole, using the CLSI M27-A3 broth microdilution (BMD) method (24-h incubation), in order to define wild-type (WT) populations and epidemiological cutoff values (ECVs). From 2001 to 2009, 8,619 isolates of Candida albicans, 2,415 isolates of C. glabrata, 2,278 isolates of C. parapsilosis, 1,895 isolates of C. tropicalis, 508 isolates of C. krusei, 205 isolates of C. lusitaniae, 177 isolates of C. guilliermondii, and 93 isolates of C. kefyr were obtained from over 100 centers worldwide. The modal MICs (µg/ml) for posaconazole and voriconazole, respectively, were as follows: for C. albicans, 0.016 and 0.007; for C. glabrata, 0.5 and 0.06; for C. parapsilosis, 0.06 and 0.007; for C. tropicalis, 0.03 and 0.015; for C. krusei, 0.25 and 0.12; for C. lusitaniae, 0.03 and 0.007; for C. guilliermondii, 0.12 and 0.03; and for C. kefyr, 0.06 and 0.007. The ECVs (µg/ml [% of isolates that had MICs equal to or less than the ECV]) for posaconazole and voriconazole, respectively, were as follows: 0.06 (98.5) and 0.03 (98.9) for C. albicans, 2 (96.2) and 0.5 (90.4%) for C. glabrata, 0.25 (99.3) and 0.12 (97.9) for C. parapsilosis, 0.12 (97.6) and 0.06 (97.2) for C. tropicalis, 0.5 (99.8) and 0.5 (99.4) for C. krusei, 0.12 (95.6) and 0.03 (96.6) for C. lusitaniae, 0.5 (98.9) and 0.25 (98.3) for C. guilliermondii, and 0.25 (100.0) and 0.015 (100.0) for C. kefyr. In the absence of clinical breakpoints (CBPs) for posaconazole, these WT distributions and ECVs will be useful in surveillance for emergence of reduced susceptibility to posaconazole among Candida spp. Whereas a CBP for susceptibility of ≤ 1 µg/ml has been established for voriconazole and all species of Candida, it is notable that ECVs for this agent range from 10- to >100-fold lower than the CBP, depending on the species of Candida. The CBP is inadequate in detecting the emergence of voriconazole resistance among most Candida species encountered clinically. The CBPs for voriconazole should be reassessed, with consideration for development of species-specific CBPs.

Use of epidemiological cutoff values to examine 9-year trends in susceptibility of Candida species to anidulafungin, caspofungin, and micafungin.

The CLSI clinical breakpoint (CBP) for echinocandin susceptibility (S; MICs of ≤ 2 µg/ml) may classify isolates with acquired resistance (R) mutations as susceptible. Epidemiological cutoff values (ECVs) have been established to distinguish wild-type (WT) Candida strains from those that may exhibit R mutations. The CLSI-developed ECVs for anidulafungin, caspofungin, and micafungin were applied to 15,269 isolates of Candida spp. collected from over 100 centers worldwide between 2001 and 2009 to determine the frequency of non-WT strains of each species. The collection included 8,378 isolates of Candida albicans, 2,352 isolates of C. glabrata, 2,195 isolates of C. parapsilosis, 1,841 isolates of C. tropicalis, and 503 isolates of C. krusei. The mean percentages of non-WT isolates per year for anidulafungin, caspofungin, and micafungin, respectively, were as follows: for C. albicans, 0.3, 0.1, and 2.1; for C. glabrata, 0.8, 1.3, and 1.6; for C. parapsilosis, 0.0, 1.5, and 0.5; for C. tropicalis, 0.9, 0.7, and 0.9; and for C. krusei, 0.5, 6.4, and 3.5. We noted increases in the percentage of non-WT isolates, from 0.5% (2001) to 3.1% (2009) for caspofungin and C. parapsilosis, from 0.4% (2004) to 1.8% (2009) for anidulafungin and C. glabrata, from 2.4% (2004) to 5.7% (2009) for micafungin and C. krusei, and from 0.0% (2004) to 3.1% (2009) for micafungin and C. parapsilosis. No trends were noted for any species and drug when we used the CBP. Echinocandin CBPs are insensitive for detecting emerging R. Although uncommon, decreased S among Candida isolates was observed for each of the echinocandins and varied by species. Using ECVs is important in determining R trends among echinocandins and Candida.

Use of epidemiological cutoff values to examine 9-year trends in susceptibility of Aspergillus species to the triazoles.

In the absence of clinical breakpoints, epidemiological cutoff values (ECVs) have been established to distinguish wild-type (WT) isolates of Aspergillus spp. from those that may harbor resistance mutations. Recently, the CLSI has developed ECVs for triazoles (itraconazole, posaconazole, and voriconazole) and common Aspergillus species. We applied the triazole ECVs to 1,789 Aspergillus isolates collected from 63 centers worldwide from 2001 to 2009 to determine the frequency of non-WT strains of each species. Temporal trends were evaluated for Aspergillus fumigatus and Aspergillus flavus over the 9-year period for each drug. The collection included 1,312 isolates of A. fumigatus, 235 of A. flavus, 162 of Aspergillus niger, 64 of Aspergillus terreus, and 15 of Aspergillus versicolor. Using the ECVs, the percentages of non-WT isolates for itraconazole, posaconazole, and voriconazole, respectively, were as follows: A. fumigatus (2.0%, 3.5%, and 1.4%), A. flavus (0.8%, 5.1%, and 1.7%), A. niger (17.3%, 3.7%, and 0.6%), A. terreus (0.0%, 1.6%, and 3.2%), and A. versicolor (6.3%, 0.0%, and 0.0%). Among 49 Aspergillus isolates for which itraconazole MICs were >2 µg/ml, the posaconazole and voriconazole MICs were greater than the ECVs for 14 and 12 isolates, respectively. The percentages of isolates for which MICs were greater than the ECVs ranged from 1.1 to 5.7% for posaconazole, 0.0 to 1.6% for voriconazole, and 0.7 to 4.0% for itraconazole. There was no consistent trend toward decreased susceptibility for any triazole and A. fumigatus or A. flavus over time. Decreased susceptibility among Aspergillus spp. was observed for each of the extended-spectrum triazoles and varied by species over the 9-year study period.

Wild-type MIC distributions and epidemiological cutoff values for the echinocandins and Candida spp.

We tested a global collection of Candida sp. strains against anidulafungin, caspofungin, and micafungin, using CLSI M27-A3 broth microdilution (BMD) methods, in order to define wild-type (WT) populations and epidemiological cutoff values (ECVs). From 2003 to 2007, 8,271 isolates of Candida spp. (4,283 C. albicans, 1,236 C. glabrata, 1,238 C. parapsilosis, 996 C. tropicalis, 270 C. krusei, 99 C. lusitaniae, 88 C. guilliermondii, and 61 C. kefyr isolates) were obtained from over 100 centers worldwide. The modal MICs (in microg/ml) for anidulafungin, caspofungin, and micafungin, respectively, for each species were as follows: C. albicans, 0.03, 0.03, 0.015; C. glabrata, 0.06, 0.03, 0.015; C. tropicalis, 0.03, 0.03, 0.015; C. kefyr, 0.06, 0.015, 0.06; C. krusei, 0.03, 0.06, 0.06; C. lusitaniae, 0.05, 0.25, 0.12; C. parapsilosis, 2, 0.25, 1; and C. guilliermondii, 2, 0.5. 05. The ECVs, expressed in microg/ml (percentage of isolates that had MICs that were less than or equal to the ECV is shown in parentheses) for anidulafungin, caspofungin, and micafungin, respectively, were as follows: 0.12 (99.7%), 0.12 (99.8%), and 0.03 (97.7%) for C. albicans; 0.25 (99.4%), 0.12 (98.5%), and 0.03 (98.2%) for C. glabrata; 0.12 (98.9%), 0.12 (99.4%), and 0.12 (99.1%) for C. tropicalis; 0.25(100%), 0.03 (100%), and 0.12 (100%) for C. kefyr; 0.12 (99.3%), 0.25 (96.3%), and 0.12 (97.8%) for C. krusei; 2 (100%), 0.5 (98.0%), and 0.5 (99.0%) for C. lusitaniae; 4 (100%), 1 (98.6%), and 4 (100%) for C. parapsilosis; 16 (100%), 4 (95.5%), and 4 (98.9%) for C. guilliermondii. These WT MIC distributions and ECVs will be useful in surveillance for emerging reduced echinocandin susceptibility among Candida spp. and for determining the importance of various FKS1 or other mutations.

In vitro susceptibility of clinical isolates of Aspergillus spp. to anidulafungin, caspofungin, and micafungin: a head-to-head comparison using the CLSI M38-A2 broth microdilution method.

We determined the in vitro activities of anidulafungin, caspofungin, and micafungin against 526 isolates of Aspergillus spp. (64 A. flavus, 391 A. fumigatus, 46 A. niger, and 25 A. terreus isolates) collected from over 60 centers worldwide from 2001 through 2007. Susceptibility testing was performed according to the CLSI M38-A2 method. All three echinocandins--anidulafungin (50% minimum effective concentration [MEC50], 0.007 microg/ml; MEC90, 0.015 microg/ml), caspofungin (MEC50, 0.015 microg/ml; MEC90, 0.03 microg/ml), and micafungin (MEC50, 0.007 microg/ml; MEC90, 0.015 microg/ml)-were very active against Aspergillus spp. More than 99% of all isolates were inhibited by < or = 0.06 microg/ml of all three agents.

In vitro activity of seven systemically active antifungal agents against a large global collection of rare Candida species as determined by CLSI broth microdilution methods.

Five Candida species (C. albicans, C. glabrata, C. tropicalis, C. parapsilosis, and C. krusei) account for over 95% of invasive candidiasis cases. Some less common Candida species have emerged as causes of nosocomial candidiasis, but there is little information about their in vitro susceptibilities to antifungals. We determined the in vitro activities of fluconazole, voriconazole, posaconazole, amphotericin B, anidulafungin, caspofungin, and micafungin against invasive, unique patient isolates of Candida collected from 100 centers worldwide between January 2001 and December 2007. Antifungal susceptibility testing was performed by the CLSI M27-A3 method. CLSI breakpoints for susceptibility were used for fluconazole, voriconazole, anidulafungin, caspofungin, and micafungin, while a provisional susceptibility breakpoint of < or = 1 microg/ml was used for amphotericin and posaconazole. Of 14,007 Candida isolates tested, 658 (4.7%) were among the less common species. Against all 658 isolates combined, the activity of each agent, expressed as the MIC50/MIC90 ratio (and the percentage of susceptible isolates) was as follows: fluconazole, 1/4 (94.8%); voriconazole, 0.03/0.12 (98.6%); posaconazole, 0.12/0.5 (95.9%); amphotericin, 0.5/2 (88.3%); anidulafungin, 0.5/2 (97.4%); caspofungin, 0.12/0.5 (98.0%); and micafungin, 0.25/1 (99.2%). Among the isolates not susceptible to one or more of the echinocandins, most (68%) were C. guilliermondii. All isolates of the less common species within the C. parapsilosis complex (C. orthopsilosis and C. metapsilosis) were susceptible to voriconazole, posaconazole, anidulafungin, caspofungin, and micafungin. Over 95% of clinical isolates of the rare Candida species were susceptible to the available antifungals. However, activity did vary by drug-species combination, with some species (e.g., C. rugosa and C. guilliermondii) demonstrating reduced susceptibilities to commonly used agents such as fluconazole and echinocandins.

Variation in susceptibility of bloodstream isolates of Candida glabrata to fluconazole according to patient age and geographic location in the United States in 2001 to 2007.

We examined the susceptibilities to fluconazole of 642 bloodstream infection (BSI) isolates of Candida glabrata and grouped the isolates by patient age and geographic location within the United States. Susceptibility of C. glabrata to fluconazole was lowest in the northeast region (46%) and was highest in the west (76%). The frequencies of isolation and of fluconazole resistance among C. glabrata BSI isolates were higher in the present study (years 2001 to 2007) than in a previous study conducted from 1992 to 2001. Whereas the frequency of C. glabrata increased with patient age, the rate of fluconazole resistance declined. The oldest age group (> or = 80 years) had the highest proportion of BSI isolates that were C. glabrata (32%) and the lowest rate of fluconazole resistance (5%).

Validation of 24-hour fluconazole MIC readings versus the CLSI 48-hour broth microdilution reference method: results from a global Candida antifungal surveillance program.

We performed 24- and 48-h MIC determinations and disk diffusion testing of fluconazole against more than 11,000 clinical isolates of Candida species. By using the reference MIC breakpoints, the categorical agreement between the 24-h and reference 48-h broth microdilution results ranged from 93.8% (all Candida species) to 94.9% (all Candida species minus Candida krusei), with only 0.1% very major errors (VME). The essential agreement (within 2 log(2) dilutions) between the 24-h and 48-h results was 99.6%. The categorical agreement between the 24-h disk diffusion results and the 24-h MIC results, using the previously established breakpoints, was 94.4%, with 0.1% VME. Both the MIC and the disk diffusion results obtained for fluconazole after only 24 h of incubation may be used to determine the susceptibilities of Candida spp. to this widely used antifungal agent.

In vitro survey of triazole cross-resistance among more than 700 clinical isolates of Aspergillus species.

Few data exist to describe in vitro patterns of cross-resistance among large collections of clinical Aspergillus isolates, including those of species other than Aspergillus fumigatus. We examined 771 Aspergillus spp. clinical isolates collected from 2000 to 2006 as part of a global antifungal surveillance program (553 A. fumigatus, 76 A. flavus, 59 A. niger, 35 A. terreus, and 24 A. versicolor isolates and 24 isolates of other Aspergillus species). Antifungal susceptibility testing was performed by the Clinical and Laboratory Standards Institute (CLSI) M38-A broth dilution method with itraconazole (ITR), posaconazole (POS), ravuconazole (RAV), and voriconazole (VOR). We examined the potential for cross-resistance by using measures of correlation overall and by species. For most Aspergillus isolates (from 88% of isolates for ITR to 98% of isolates for VOR and POS), MICs of each triazole were < or = 1 microg/ml. When all 771 isolates were examined, there were statistically significant correlations for all six triazole-triazole pairs. For A. fumigatus, the strongest correlations seen were those between VOR and RAV MICs (r = 0.7) and ITR and POS MICs (r = 0.4). Similarly, for A. flavus, only VOR and RAV MICs and ITR and POS MICs demonstrated statistically significant positive correlations. We have demonstrated correlations among triazole MICs for Aspergillus, which for the most common species (A. fumigatus and A. flavus) were strongest between VOR and RAV MICs and ITR and POS MICs. However, Aspergillus species for which MICs of VOR or POS were >2 microg/ml remain extremely rare (<1% of isolates).

Selection of a surrogate agent (fluconazole or voriconazole) for initial susceptibility testing of posaconazole against Candida spp.: results from a global antifungal surveillance program.

There are currently no FDA-approved broth microdilution antifungal susceptibility testing products or interpretive breakpoints for susceptibility testing of the new triazole posaconazole. Fluconazole and voriconazole are in the same triazole class as posaconazole, have CLSI-approved interpretive MIC breakpoints, and are available on some commercially available MIC panels. We investigated whether one or both of these agents may be useful as a surrogate marker for posaconazole susceptibility. Fluconazole, voriconazole, and posaconazole MIC results for 10,807 isolates of Candida spp. were analyzed to validate a potential surrogate marker for posaconazole activity against indicated species. For illustrative purposes, we applied the voriconazole MIC breakpoints to posaconazole (susceptible, < or =1 microg/ml; susceptible dose dependent, 2 microg/ml; resistant, > or =4 microg/ml) and compared these MIC results and categorical interpretations with those of fluconazole and voriconazole by using regression statistics and categorical agreement. For all 10,807 isolates, the absolute categorical agreement was 91.1% (0.1% very major errors [VME], 1.2% major errors [ME], and 7.6% minor errors [M]) using fluconazole as the surrogate marker and 97.7% (0.3% VME 0.1% ME, and 1.9% M) using voriconazole as the surrogate. The results with fluconazole improved to a categorical agreement of 93.7% (0.1% VME, 0.2% ME, and 6.0% M) when results for Candida krusei (not indicated for fluconazole testing) were omitted. Either fluconazole or voriconazole MIC results may serve as surrogate markers to predict the susceptibility of Candida spp. to posaconazole.

In vitro susceptibility of invasive isolates of Candida spp. to anidulafungin, caspofungin, and micafungin: six years of global surveillance.

The echinocandins are being used increasingly as therapy for invasive candidiasis. Prospective sentinel surveillance for the emergence of in vitro resistance to the echinocandins among invasive Candida sp. isolates is indicated. We determined the in vitro activities of anidulafungin, caspofungin, and micafungin against 5,346 invasive (bloodstream or sterile-site) isolates of Candida spp. collected from over 90 medical centers worldwide from 1 January 2001 to 31 December 2006. We performed susceptibility testing according to the CLSI M27-A2 method and used RPMI 1640 broth, 24-h incubation, and a prominent inhibition endpoint for determination of the MICs. Of 5,346 invasive Candida sp. isolates, species distribution was 54% C. albicans, 14% C. parapsilosis, 14% C. glabrata, 12% C. tropicalis, 3% C. krusei, 1% C. guilliermondii, and 2% other Candida spp. Overall, all three echinocandins were very active against Candida: anidulafungin (MIC50, 0.06 microg/ml; MIC90, 2 microg/ml), caspofungin (MIC50, 0.03 microg/ml; MIC90, 0.25 microg/ml), micafungin (MIC50, 0.015 microg/ml; MIC90, 1 microg/ml). More than 99% of isolates were inhibited by < or = 2 microg/ml of all three agents. Results by species (expressed as the percentages of isolates inhibited by < or = 2 microg/ml of anidulafungin, caspofungin, and micafungin, respectively) were as follows: for C. albicans, 99.6%, 100%, and 100%; for C. parapsilosis, 92.5%, 99.9%, and 100%; for C. glabrata, 99.9%, 99.9%, and 100%; for C. tropicalis, 100%, 99.8%, and 100%; for C. krusei, 100%, 100%, and 100%; and for C. guilliermondii, 90.2%, 95.1%, and 100%. There was no significant change in the activities of the three echinocandins over the 6-year study period and no difference in activity by geographic region. All three echinocandins have excellent in vitro activities against invasive strains of Candida isolated from centers worldwide. Our prospective sentinel surveillance reveals no evidence of emerging echinocandin resistance among invasive clinical isolates of Candida spp.

Use of fluconazole as a surrogate marker to predict susceptibility and resistance to voriconazole among 13,338 clinical isolates of Candida spp. Tested by clinical and laboratory standards institute-recommended broth microdilution methods.

Clinical laboratories frequently face the problem of delayed availability of commercially prepared approved reagents for performing susceptibility testing of new antimicrobials. Although this problem is encountered more often with antibacterial agents, it is also an issue with antifungal agents. A current example is voriconazole, a new triazole antifungal with an expanded spectrum and potency against Candida spp., Aspergillus spp., and other opportunistic fungal pathogens. The present study addresses the use of fluconazole as a surrogate marker to predict the susceptibility of Candida spp. to voriconazole. Reference broth microdilution MIC results for 13,338 strains of Candida spp. isolated from more than 200 medical centers worldwide were used. Voriconazole MICs and interpretive categories (susceptible, < or =1 microg/ml; susceptible dose dependent, 2 microg/ml; resistant, > or =4 microg/ml) were compared with those of fluconazole by regression statistics and error rate bounding analyses. For all 13,338 isolates, the absolute categorical agreement was 91.6% (false susceptible or very major error [VME], 0.0%). Since voriconazole is 16- to 32-fold more potent than fluconazole, the performance of fluconazole as a surrogate marker for voriconazole susceptibility was improved by designating those isolates with fluconazole MICs of < or =32 microg/ml as being susceptible to voriconazole, resulting in a categorical agreement of 97% with 0.1% VME. Clinical laboratories performing antifungal susceptibility testing of fluconazole against Candida spp. can reliably use these results as surrogate markers until commercial FDA-approved voriconazole susceptibility tests become available.

Global surveillance of in vitro activity of micafungin against Candida: a comparison with caspofungin by CLSI-recommended methods.

Micafungin is an echinocandin antifungal agent that has recently been approved for the prevention of invasive fungal infection and the treatment of esophageal candidiasis. Prospective sentinel surveillance for the emergence of in vitro resistance to micafungin among invasive Candida sp. isolates is indicated. We determined the in vitro activity of micafungin against 2,656 invasive (bloodstream or sterile site) unique patient isolates of Candida spp. collected from 60 medical centers worldwide in 2004 and 2005. We performed antifungal susceptibility testing according to the Clinical and Laboratory Standards Institute (CLSI) M27-A2 method and used a 24-hour prominent inhibition endpoint for determination of the MIC. Caspofungin was tested in parallel against all isolates. Of 2,656 invasive Candida sp. isolates, species distribution was 55.6% Candida albicans, 14.4% Candida parapsilosis, 13.4% Candida glabrata, 10.1% Candida tropicalis, 2.4% Candida krusei, 1.7% Candida guilliermondii, 0.9% Candida lusitaniae, 0.6% Candida kefyr, and 0.9% other Candida species. Overall, micafungin was very active against Candida (MIC50/MIC at which 90% of the isolates tested are inhibited [MIC90], 0.015/1 microg/ml; 96% inhibited at a MIC of < or =1 microg/ml, 100% inhibited at a MIC of < or =2 microg/ml) and comparable to caspofungin (MIC50/MIC90, 0.03/0.25 mug/ml; 99% inhibited at a MIC of < or =2 microg/ml). Results by species, expressed as MIC50/MIC90 (micrograms per milliliter), were as follows: C. albicans, 0.015/0.03; C. glabrata, 0.015/0.015; C. tropicalis, 0.03/0.06; C. krusei, 0.06/0.12; C. kefyr, 0.06/0.06; C. parapsilosis, 1/2; C. guilliermondii, 0.5/1; C. lusitaniae, 0.12/0.25; other Candida spp., 0.25/1. Although the species distribution varied considerably among the different geographic regions, there was no difference in micafungin activity across the regions. Micafungin has excellent in vitro activity against invasive clinical isolates of Candida from centers worldwide.

In vitro susceptibilities of Candida spp. to caspofungin: four years of global surveillance.

Caspofungin is being used increasingly as therapy for invasive candidiasis. Prospective sentinel surveillance for emergence of in vitro resistance to caspofungin among invasive Candida spp. isolates is indicated. We determined the in vitro activity of caspofungin against 8,197 invasive (bloodstream or sterile-site) unique patient isolates of Candida collected from 91 medical centers worldwide from 1 January 2001 to 31 December 2004. We performed antifungal susceptibility testing according to the Clinical and Laboratory Standards Institute (CLSI, formerly NCCLS) M27-A2 method and used a 24-h prominent inhibition endpoint for determination of the MIC. Of 8,197 invasive Candida spp. isolates, species distribution was as follows: 54% Candida albicans, 14% C. glabrata, 14% C. parapsilosis, 11% C. tropicalis, 3% C. krusei, and 4% other Candida spp. Overall, caspofungin was very active against Candida (MIC50/MIC90, 0.03/0.25 microg/ml; 98.2% were inhibited at a MIC of < or = 0.5 microg/ml and 99.7% were inhibited at a MIC of < or = 1 microg/ml). Results by species (expressed as MIC50/MIC90 and the percentage inhibited at < or = 1 microg/ml) were as follows: C. albicans, 0.03/0.06, 99.9; C. glabrata, 0.03/0.06, 99.9; C. parapsilosis, 0.5/0.5, 99.0; C. tropicalis, 0.03/0.06, 99.7; C. krusei, 0.12/0.5, 99.0; and C. guilliermondii, 0.5/1, 94.4. Of the 25 isolates with caspofungin MICs of >1 microg/ml, 12 isolates were C. parapsilosis, 6 isolates were C. guilliermondii, 2 isolates were C. rugosa, and 1 isolate each was C. albicans, C. glabrata, C. krusei, C. lusitaniae, and C. tropicalis. There was no significant change in caspofungin activity over the 4-year study period. Likewise, there was no difference in activity by geographic region. Caspofungin has excellent in vitro activity against invasive clinical isolates of Candida from centers worldwide. Our prospective sentinel surveillance reveals no evidence of emerging caspofungin resistance among invasive clinical isolates of Candida.

Activities of micafungin against 315 invasive clinical isolates of fluconazole-resistant Candida spp.

Micafungin is a new echinocandin exhibiting broad-spectrum activity against Candida spp. The activity of the echinocandins against Candida species known to express intrinsic or acquired resistance to fluconazole is of interest. We determined the MICs of micafungin and caspofungin against 315 invasive clinical (bloodstream and other sterile-site) isolates of fluconazole-resistant Candida species obtained from geographically diverse medical centers between 2001 and 2004. MICs were determined using broth microdilution according to the CLSI reference method M27-A2. RPMI 1640 was used as the test medium, and we used the MIC endpoint of prominent growth reduction at 24 h. Among the 315 fluconazole-resistant Candida isolates, 146 (46%) were C. krusei, 110 (35%) were C. glabrata, 41 (13%) were C. albicans, and 18 (6%) were less frequently isolated species. Micafungin had good in vitro activity against all fluconazole-resistant Candida spp. tested; the MICs at which 50% (MIC(50)) and 90% (MIC(90)) of isolates were inhibited were 0.03 microg/ml and 0.06 microg/ml, respectively. All the fluconazole-resistant Candida spp. were inhibited at a micafungin MIC that was

In vitro activities of anidulafungin against more than 2,500 clinical isolates of Candida spp., including 315 isolates resistant to fluconazole.

Anidulafungin is an echinocandin antifungal agent with potent activity against Candida spp. We assessed the in vitro activity of anidulafungin against 2,235 clinical isolates of Candida spp. using the CLSI broth microdilution method. Anidulafungin was very active against Candida spp. (the MIC at which 90% of strains are inhibited [MIC(90)] was 2 microg/ml when MIC endpoint criteria of partial inhibition [MIC-2] were used). Candida albicans, C. glabrata, C. tropicalis, C. krusei, and C. kefyr were the most susceptible species of Candida (MIC(90), 0.06 to 0.12 microg/ml), and C. parapsilosis, C. lusitaniae, and C. guilliermondii were the least susceptible (MIC(90), 0.5 to 2 microg/ml). In addition, 315 fluconazole-resistant isolates were tested, and 99% were inhibited by < or =1 microg/ml of anidulafungin. These results provide further evidence for the spectrum and potency of anidulafungin activity against a large and geographically diverse collection of clinically important isolates of Candida spp.