189株肺部酵母样真菌的鉴定及E-test法药敏分析

[目的] 研究临床上肺部酵母样真菌感染的菌种组成及药敏试验。[方法] 对189株临床分离株进行鉴定并用E-test法做药敏试验，测定其对4种抗真菌药的最小抑菌浓度(MIC)。[结果] 分离出的189株酵母样真菌中以白色念珠菌和副秃发念珠菌为主，分别为115株(60．8％)和26株(13．9％)。对4种药物试条的MIC值；两性霉素B(AP)为0．012-2μg/ml，5氟胞嘧啶(FC)和伊曲康唑(IT)均为0．032-32μg/ml，氟康唑(FL)为0．032-256μg/ml，FC、FL和IT的敏感率分别为93．7％、67．1％和38．0％，AP、FC、FL和IT的耐药率分别为1．3％、2．5％、27．8％和34．1％。[结论] FC对白色念珠菌和副秃发念珠菌的抑菌效果好，AP的耐药率较低，FL和IT的耐药现象较严重。     

儿科患者中真菌分布及耐药监测

目的了解我院2000-2006年临床深部真菌感染分离的病原真菌种类及对抗真菌药物的耐药性变化。方法分析2000年1月～2006年12月年我院住院患儿所有送检真菌培养标本中分离出的菌株，药敏试验使用ATB-FUNGUS2INT酵母药敏试条，进行5-氟胞嘧啶、氟康唑和两性霉素B3种抗真菌药敏检测，严格按照2006年CLSIM27-A2规则及标准进行。结果分离出635株真菌中，念珠菌属572株（90．1％），曲霉属29株（4．6％），隐球菌属21株（3．3％），青霉属和酵母属各5株（0．8％），毛孢菌属2株（0．3％），毛霉属1株（0．2％）。念珠菌属中，前3位分离菌是白念珠菌418株（73．1％）；光滑念珠菌64株（11．2％）；热带念珠菌52株（9．1％）。白念珠菌对5-氟胞嘧啶、氟康唑和两性霉素B敏感率分别为97．6％，97．6％和98．4％。结论儿科患者中分离的真菌中以念珠菌属最多，并以白念珠菌为主，曲霉比率也在增多。5-氟胞嘧啶、氟康唑和两性霉素B均有较高的抗真菌活性。应加强真菌分离鉴定和耐药性监测，供合理选用抗真菌药物的参考。     

E test法检测3种抗真菌药物对128株酵母菌的体外活性

目的调查我院酵母菌对氟康唑等3种抗菌药的敏感性，指导临床用药。方法使用Etest法测定3种抗真菌药对128株酵母菌的MIC。结果两性霉素B对128株酵母菌的抗菌活性最强(敏感率94．5％，MIC50和MIC90分别为0．25和1mg／L)，其次为氟康唑和伊曲康唑(前者敏感率92．2％，MIC50和MIC90为2和8mg／L；后者为64．1％．MIC50和MIC90为0．064和0．75mg／L)；71株白念珠菌对两性霉素B、氟康唑和伊曲康唑的敏感率分别为100％、98．5％和91．6％；30株热带念珠菌对氟康唑、两性霉素B和伊曲康唑的敏感率分别为96．7％、86．7％和19．9％；12株光滑念珠菌对两性霉素B、氟康唑和伊曲康唑的敏感率分别为100％、74．9％和33．3％。结论我院自念珠菌对3种抗真菌药高度敏感，非白念念珠菌对3种抗真菌药表现不同程度耐药，应加强对非白念念珠菌耐药性的监控。     

国产伏立康唑对临床分离病原真菌体外抗菌活性研究

目的了解国产伏立康唑对北京和我国其他地区临床分离的常见病原真菌体外抗菌活性。方法分别参照CLSIM27-A2和M38-A方案测定伏立康唑对144株酵母和82株产孢丝状真菌的抗菌活性。受试菌株包括念珠菌114株（含氟康唑获得性耐药白念珠菌）、新型隐球菌20株、阿萨希毛孢子菌10株、曲霉62株（含伊曲康唑耐药曲霉及两性霉素B不敏感曲霉）、镰刀菌10株、尖端赛多孢菌10株。结果伏立康唑对念珠菌（不包括氟康唑耐药和剂量依赖敏感白念珠菌）、新型隐球菌、阿萨希毛孢子菌的MIC50≤0．5mg／L、MIC90≤1mg／L；而对氟康唑获得性耐药白念珠菌MIC50和MIC90均〉16mg／L。对曲霉、尖端赛多孢菌的MIC50≤1mg／L、MIC90≤2mg／L，对镰刀菌的MIC50和MIC90分别为4mg／L和〉16mg／L。结论伏立康唑对多数酵母有较强的体外抗菌活性，尤其是对克柔念珠菌和光滑念珠菌等氟康唑天然耐药菌株。该药对多数产孢丝状真菌也有较好的体外抗菌作用，包括伊曲康唑耐药及两性霉素B不敏感的曲霉以及对多种抗真菌药物耐药的尖端赛多孢菌；但其对氟康唑获得性耐药白念珠菌有一定交叉耐药。     

外阴阴道念珠菌病的病原检测及体外药敏检测

目的：了解性病门诊外阴阴道念珠菌病(WC)患者的病因及酵母菌体外对伊曲康唑(IT)、氟康唑(FL)的敏感性。方法：用法国梅里埃公司的试剂盒对107例疑诊为WC的阴道分泌物标本进行培养鉴定,并用E-test抗真菌药敏试条检测IT、FL对酵母菌的MIC值,判定敏感性。结果：107例阴道分泌物标本培养阳性87例,分离出自念株菌69株(79．31％,69／87),其中对IT敏感67株、中敏1株、耐药1株,对FL均敏感(69株);光滑念株菌10株(11．49％,10／87),其中对IT敏感2株、中敏2株、耐药6株,对FL敏感9株、耐药1株;近平滑念珠菌4例(4．60％,4／87),对IT敏感3株、耐药1株,对FL均敏感(4株);热带念珠菌、土生念珠菌、清酒念珠菌和埃莫毕赤念珠菌各1例(1．15％,1／87),其对IT、FL均敏感。结论：WC最常见的病因仍是自念珠菌,但比率明显下降;用Btest法检测酵母菌对IT、FL的敏感性在临床选择抗真菌药物具有一定的参考意义。     

泌尿系统真菌感染的分布及其耐药性分析

目的：了解临床泌尿系统真菌分布及其药敏情况,指导临床合理使用抗菌药物。方法对2012年1月至2013年6月期间临床送检的泌尿系统标本进行真菌鉴定,并检测其对5种抗菌药物的敏感性,结果采用 WHONET 软件进行统计学分析。结果（1）共分离出真菌239株,其中白色念珠菌居首位,其余依次为光滑念珠菌和热带念珠菌;（2）239株真菌对氟康唑（FCA）、伊曲康唑（ITR）、伏立康唑（VRC）、5-氟胞嘧啶（5-FC）及两性霉素（AMB）的敏感率分别为63．2％、61．9％、92．5％、93．7％及93．7％;（3）白色念珠菌对5种抗菌药物的敏感性较好,均达到95．0％以上;（4）光滑念珠菌对 FCA 和 ITR 的敏感性最低,仅为9．7％。结论泌尿系统真菌感染以白色念珠菌为主,由于各种念珠菌对5种抗真菌药物的敏感性不同,因此加强泌尿系统真菌鉴定及药敏检测,能够为临床合理使用抗菌药物提供重要参考依据。     

2011年呼吸道感染患者念珠菌属的病原菌比较及耐药性分析

目的：了解呼吸道念珠菌感染和耐药情况。方法收集2011年1～12月分离的呼吸道感染患者念珠菌。采用科玛嘉显色培养基对分离的493株念珠菌进行菌种鉴定,用珠海迪尔生物工程有限公司生产的细菌鉴定及药敏实验体外诊断试剂对分离株进行5种常用抗真菌药的体外敏感性检测。结果呼吸道念珠菌感染中以白色念珠菌为主316例（64．09％）,其次为光滑假丝酵母156例（31．64％）,近平滑念珠菌11例（2．23％）,热带念珠菌10例（2．03％）。对5种常用药（氟胞嘧啶、两性霉素、氟康唑、伊曲康唑、伏立康唑）进行耐药分析,念珠菌对氟康唑、伊曲康唑、伏立康唑均有较高的耐药率,唑类药物对试验念珠菌体外抑菌活性较差,其 MIC50、MIC90值较高。除了白色念珠菌和光滑假丝酵母对氟胞嘧啶、两性霉素有较低的耐药率以外,近平滑念珠菌、热带念珠菌对这两种药物的耐药率最低（0．00％）。氟胞嘧啶、两性霉素对试验念珠菌具有良好的体外抑菌活性,其 MIC50、MIC90值较低。结论呼吸道念珠菌感染主要以白色念珠菌为主,氟胞嘧啶、两性霉素对念珠菌均保持较高的体外抗菌活性,是治疗真菌的有效药物。同时,已出现不同程度的对抗真菌药物的耐药,并有增加的趋势。     

卡泊芬净对16种念珠菌体外抗菌活性研究

目的比较卡泊芬净国产与进口制剂对引起侵袭性感染的念珠菌属体外抗菌活性。方法从29所医院收集了分离自血液等无菌部位的337株念珠菌,包括白念珠菌、热带念珠菌、近平滑念珠菌、光滑念珠菌、克柔念珠菌等16种念珠菌,采用CLSI推荐的微量肉汤稀释法对8种抗真菌药物进行体外药物敏感性试验。结果除1株光滑念珠菌和1株克柔念珠菌对国产卡泊芬净中介外,其余菌株均敏感。不同菌种药敏数据显示,国产与进口卡泊芬净的MIC50和MIC90完全一致,除热带念珠菌外,国产与进口卡泊芬净对其余菌种的MIC分布范围均一致。国产卡泊芬净对常见菌种的MIC50和MIC90为白念珠菌0.064mg/L和0.125mg/L、热带念珠菌0.125mg/L和0.25mg/L、光滑念珠菌0.125mg/L和0.125mg/L、克柔念珠菌0.25mg/L和0.25mg/L,近平滑念珠菌复合体和季也蒙念珠菌的MIC50和MIC90为0.5mg/L和1mg/L,略高于上述念珠菌。分别分析氟康唑敏感和耐药的白念珠菌和热带念珠菌对棘白菌素类药物的敏感率,发现氟康唑耐药组与敏感组菌株对应的棘白菌素类药物MIC分布范围基本一致,几何均数无明显差异,并且均未发现卡泊芬净耐药菌株。结论卡泊芬净对多数念珠菌属均有较好的抗真菌活性,并且国产与进口卡泊芬净体外抗真菌活性高度一致。     

1999-2001年丽水市中心医院重症监护病房真菌耐药性分析

目的：了解丽水市中心医院重症监护病房(ICU)真菌临床分离株的耐药情况，为真菌感染的防治提供依据。方法：使用ATB-Fungus板条对1999年1月至2001年12月丽水市中心医院ICU临床真菌分离菌进行药敏试验。结果：在62株临床分离株中，白念珠菌为39株(39／62，62．9％)、其他念珠菌属23株(23／62，37．1％)；白念珠菌对酮康唑、咪康唑和益康唑的敏感率较低，分别为28．2％、35．9％和28．3％，而对两性霉素B、5-氟胞嘧啶和制霉菌素的敏感率则较高，分别为89．7％、94．9％和89．7％。结论：ICU感染中念珠菌属有逐渐增加的趋势，应引起重视。     

383例阴道真菌感染菌群鉴定及药敏分析

目的了解念珠菌性阴道炎致病菌的菌种分布情况及耐药情况。方法对念珠菌性阴道炎患者的标本运用玛嘉显色培养基法对分离自阴道念珠菌感染患者的383株念珠菌进行菌种鉴定。结果383例阴道念珠菌感染的病例经鉴定白色念珠菌368株（96．09％）,其次为光滑念珠菌10株（2．61％）,较少的有热带念珠菌4株1．04％）和克柔念珠菌1株（0．26％）。临床用7种药物中制霉菌素对阴道内真菌的敏感率最高为98．4％,两性霉素B敏感率为98．1％,酮康唑50.4％,伊曲康唑47．5％,咪康唑47．5％,氟康唑25．3％,特比萘芬23．5％。结论白色念珠菌是导致临床阴道念珠菌感染的优势菌群,其次有光滑念珠菌,热带念珠菌和克柔念珠菌等念珠菌感染。制霉菌素对阴道内真菌的敏感率最高,是治疗真菌感染的有效药物。鉴于伊曲康唑、咪康唑、氟康唑、特比萘芬等均存在不同程度的耐药,建议对反复发作的念珠菌性阴道炎患者根据药敏试验来选择药物,从而减少耐药菌株的出现,提高念珠菌性阴道炎的治愈率。     

Antifungal susceptibility of Candida spp. isolated from pediatric patients: a survey of 4 children's hospitals

Candida species are the most common cause of fungal infections in hospitalized patients. Recent studies have reported a relative reduction in the rates of infection caused by Candida albicans and a shift toward non-albicans Candida spp. Data on the distribution and susceptibility of Candida spp. from children's hospitals are limited. Clinical isolates of Candida were collected from 4 US children's hospitals in 2003. Broth dilution MICs for amphotericin B, fluconazole, voriconazole, caspofungin, posaconazole, and ravuconazole were performed according to National Committee for Clinical Laboratory Standards-approved methodology. A total of 179 clinical isolates were identified and included. Of 179, 77 (43%) were C. albicans. Candida parapsilosis isolates were the second most frequently identified (57/175, 32%), followed by Candida glabrata, Candida tropicalis, and Candida lusitaniae (approximately 8% each). Caspofungin was the most active agent in vitro against all Candida spp. Fluconazole resistance was seen among C. glabrata, C. tropicalis, and Candida krusei isolates. Newer azoles had improved activity against fluconazole-resistant isolates of Candida. Among isolates of C. parapsilosis, nearly 20% were resistant to amphotericin B. The current study highlights the emergence of C. parapsilosis as a distinct pediatric pathogen with clinical and therapeutic implications. Furthermore, our current susceptibility data include newer antifungal agents that appear to be quite active in vitro and may provide new therapeutic options for the treatment of serious yeast infections in children.     

In vitro antifungal activity of FK463, a new water-soluble echinocandin-like lipopeptide

The antifungal activity of FK463 against 72 recent clinical isolates of Candida albicans (24), Candida glabrata (17), Candida tropicalis (11), Candida krusei (8) and Candida parapsilosis (12) was compared with those of amphotericin B, fluconazole and itraconazole by means of a broth microdilution method specified by the National Committee for Clinical Laboratory Standards (NCCLS) document M27-A. The lowest drug concentration at which 90% of the population was inhibited (MIC(90)) of FK463 against C. albicans, C. glabrata, C. tropicalis, C. krusei and C. parapsilosis was 0.0156, 0. 0156, 0.0313, 0.125 and 1 mg/L, respectively. FK463 exhibited broad-spectrum activity against clinically important Candida spp. (MIC range < or =0.0039-2 mg/L), and its MICs for such fungi were lower than those of other antifungal agents tested. The minimum fungicidal concentrations for Candida spp. did not differ by more than two-fold from the MICs. Results from pre-clinical evaluations performed to date indicate that FK463 should be a potent parenteral antifungal agent.     

Antifungal susceptibility testing of Candida spp. by relative growth measurement at single concentrations of antifungal agents.

The relative growth (percentage of growth relative to control growth) of 496 isolates representing six Candida species was assessed as a means of determining in vitro susceptibilities of the isolates in microdilution plate wells containing single concentrations of each of seven antifungal agents. The relative growth data were highly reproducible. With flucytosine and amorolfine they correlated well with MICs, but for an azole antifungal agent, terconazole, they did not correlate with MICs. Distributions of relative growth percentages for different Candida spp. showed significant differences in species susceptibility to individual agents. For example, C. albicans was less susceptible than the other species to amorolfine; C. parapsilosis isolates were particularly susceptible to terbinafine; and C. glabrata, C. guilliermondii, and C. krusei isolates were less susceptible than C. albicans to fluconazole and ketoconazole but equally susceptible as or more susceptible than C. albicans to itraconazole. Differential patterns of susceptibility to individual azole antifungal agents were noted for some individual strains as well as for Candida spp.     

In vitro activities of caspofungin compared with those of fluconazole and itraconazole against 3,959 clinical isolates of Candida spp., including 157 fluconazole-resistant isolates

Caspofungin is an echinocandin antifungal agent with broad-spectrum activity against Candida and Aspergillus spp. The in vitro activities of caspofungin against 3,959 isolates of Candida spp. obtained from over 95 different medical centers worldwide were compared with those of fluconazole and itraconazole. The MICs of the antifungal drugs were determined by broth microdilution tests performed according to the NCCLS method using RPMI 1640 as the test medium. Caspofungin was very active against Candida spp. (MIC at which 90% of the isolates were inhibited [MIC(90)], 1 micro g/ml; 96% of MICs were < or =2 micro g/ml). Candida albicans, C. dubliniensis, C. tropicalis, and C. glabrata were the most susceptible species of Candida (MIC(90), 0.25 to 0.5 micro g/ml), and C. guilliermondii was the least susceptible (MIC(90), >8 micro g/ml). Caspofungin was very active against Candida spp., exhibiting high-level resistance to fluconazole and itraconazole (99% of MICs were < or =1 micro g/ml). These results provide further evidence for the spectrum and potency of caspofungin activity against a large and geographically diverse collection of clinically important isolates of Candida spp.     

In vitro activities of posaconazole (Sch 56592) compared with those of itraconazole and fluconazole against 3,685 clinical isolates of Candida spp. and Cryptococcus neoformans

Posaconazole is a new investigational triazole with broad-spectrum antifungal activity. The in vitro activities of posaconazole were compared with those of itraconazole and fluconazole against 3,685 isolates of Candida spp. (3,312 isolates) and C. neoformans (373 isolates) obtained from over 70 different medical centers worldwide. The MICs of the antifungal drugs were determined by broth microdilution tests performed according to the National Committee for Clinical Laboratory Standards method using RPMI 1640 as the test medium. Posaconazole was very active against all Candida spp. (MIC at which 90% of the isolates were inhibited [MIC(90)], 0.5 microg/ml; 97% of MICs were < or =1 microg/ml) and C. neoformans (MIC(90), 0.5 microg/ml; 100% of MICs were < or =1 microg/ml). Candida albicans was the most susceptible species of Candida (MIC(90), 0.06 microg/ml), and Candida glabrata was the least susceptible (MIC(90), 4 microg/ml). Posaconazole was more active than itraconazole and fluconazole against all Candida spp. and C. neoformans. These results provide further evidence for the spectrum and potency of posaconazole against a large and geographically diverse collection of clinically important fungal pathogens.     

Trends in species distribution and susceptibility to fluconazole among blood stream isolates of Candida species in the United States

National surveillance of blood stream infections (BSI) attributable to Candida spp. has been limited to date. Recent studies have suggested in increase in the proportion of BSI attributable to non-Candida albicans species and have also raised concerns regarding the emergence of antifungal resistance among Candida spp. The increased utilization of broad-spectrum antifungal agents and the recognition of Candida spp. as prominent pathogens with the potential for developing antifungal resistance, emphasize the need for ongoing surveillance of antifungal susceptibility patterns. In this investigation trends in species distribution and susceptibility to fluconazole among BSI isolates of Candida spp. referred to our laboratory by United States hospitals were evaluated over the 7-year period from 1992 to 1998. A total of 1579 BSI isolates from more than 50 medical centers were processed. Overall, C. albicans accounted for 52% of isolates followed by C. glabrata (18%), C. parapsilosis (15%), C. tropicalis (11%), and C. krusei (2%). The proportion of BSI isolates that were C. albicans ranged from 45% in 1992 to 60% in 1998. Among the non-C. albicans isolates, C. glabrata succeeded C. parapsilosis as the most common species beginning in 1995. Overall, the susceptibility of all Candida species (C. albicans plus all other species) to fluconazole remained stable (MIC90, 16 micrograms/mL). The fluconazole MIC90 for C. albicans was 0.5-2.0 micrograms/ml for all years studied except 1995 (8.0 micrograms/mL) and was 1.0 microgram/mL overall. The present study suggests a continued prominent role of C. albicans as a cause of BSI, and a constant level of susceptibility of Candida BSI isolates to fluconazole over 7 years. These data should serve as a baseline for future surveillance efforts for anti-fungal agents tested against yeast BSI isolates.     

In vitro activity of 2-cyclohexylidenhydrazo-4-phenyl-thiazole compared with those of amphotericin B and fluconazole against clinical isolates of Candida spp. and fluconazole-resistant Candida albicans

OBJECTIVES: The aim of this study was to investigate the in vitro antifungal activity of an isothiosemicarbazone cyclic analogue against isolates of Candida spp. including fluconazole-resistant Candida albicans. METHODS: We investigated the activity of 2-cyclohexylidenhydrazo-4-phenyl-thiazole (EM-01D2) against 114 clinical isolates of Candida spp., representing five different species, by microdilution, according to the NCCLS method 27-A. The activity against C. albicans biofilms was also investigated. Toxicity in vitro was evaluated by MTT reduction assay. RESULTS: EM-01D2 demonstrated low toxicity, broad spectrum, fungicidal activity and was active against C. albicans and Candida krusei at concentrations lower than those shown by amphotericin B and fluconazole (P < 0.05). It maintained potent in vitro activity against fluconazole-resistant C. albicans isolates. Fungicidal activity occurred at concentrations 1-2 doubling dilutions greater than the corresponding MICs, and time-kill analysis indicated that a 99.9% loss of C. albicans viability occurred after 6 h of incubation in the presence of EM-01D2 at concentrations equal to four times the MIC. EM-01D2 was also active in inhibiting the growth of C. albicans ATCC 10231 biofilms, even though such inhibition occurred at concentrations higher than the MICs determined under planktonic growth conditions. However, when C. albicans biofilms were pre-exposed to subinhibitory concentrations of EM-01D2, a reduction of MIC50 of amphotericin B was observed. CONCLUSIONS: Based on these results, EM-01D2 could represent a template for the development of novel fungicidal agents.     

In vitro activities of voriconazole (UK-109,496) against fluconazole-susceptible and -resistant Candida albicans isolates from oral cavities of patients with human immunodeficiency virus infection.

The susceptibility of Candida albicans to a new antifungal triazole, voriconazole (UK-109,496), was investigated in 105 isolates obtained from the oral cavities of patients with human immunodeficiency virus (HIV) infection to study this drug's activity against fluconazole-susceptible and -resistant isolates. MICs were determined by a broth microdilution technique according to document M27-T from the National Committee for Clinical Laboratory Standards and by using a broth microdilution technique and a synthetic high-resolution medium. These antifungal susceptibility testing methods showed high levels of agreement (93% for fluconazole and 86% for voriconazole). Data from in vitro studies showed that voriconazole has good activity against fluconazole-susceptible and -resistant C. albicans isolates; the MICs at which 90% of all isolates were inhibited were 0.19 to 0.39 microgram/ml. We found that for isolates for which fluconazole MICs were high, voriconazole MICs were proportionally higher than those for fluconazole-susceptible C.albicans (P < 0.001). Pretreatment isolates from six patients with fluconazole-refractory esophageal candidiasis were included in the study. For these isolates the MICs were < or = 0.39 microgram/ml, and all patients responded to voriconazole. These results suggest that voriconazole is effective even in the treatment of fluconazole-refractory esophageal candidiasis and should be studied further to determine its clinical relevance in patients with HIV infection.     

Susceptibility of fluconazole-resistant clinical isolates of Candida spp. to echinocandin LY303366, itraconazole and amphotericin B

The in vitro activity of LY303366 was compared with those of itraconazole and amphotericin B against 156 fluconazole-resistant (MIC > or = 16 mg/L) clinical isolates of CANDIDA: spp. An adaptation of the NCCLS reference method was employed for determination of MICs. LY303366 was more potent than either itraconazole or amphotericin B against Candida albicans, Candida glabrata, Candida krusei and Candida tropicalis, even against isolates with itraconazole MICs > or = 1 mg/L. LY303366 was less potent in vitro against Candida parapsilosis and Candida guilliermondii isolates. LY303366 has promising antifungal activity and warrants further investigation.     

Trends in frequency and in vitro susceptibilities to antifungal agents,including voriconazole and anidulafungin,of Candida bloodstream isolates. Results from a six-year study (1996-2001)

The frequency of isolation and antifungal susceptibility patterns to established and two new antifungal agents were determined for 218 Candida spp isolates causing bloodstream infection from 1996 to 2001. Overall, 41.7% of the candidemias were due to C. albicans, followed by C. parapsilosis (22%), C. tropicalis (16.1%), C. glabrata (11.9%), C. krusei (6%) and miscellaneous Candida spp (2.3%). Isolates of C. albicans C. parapsilosis and C. tropicalis (80% of isolates) were highly susceptible to fluconazole (94 to 100% at /= 32 microg/ml).