Third-Generation Cephalosporin-Resistant Vibrio cholerae, India

Vibrio cholerae resistance to third-generation cephalosporins is rarely reported. We detected a strain that was negative for extended-spectrum β-lactamase and positive for the AmpC disk test, modified Hodge test, and EDTA disk synergy test and harbored the blaDHA-1 and blaNDM-1 genes. The antimicrobial drug susceptibility profile of V. cholerae should be monitored.     

ESBL genotypes in fluoroquinolone-resistant and fluoroquinolone-susceptible ESBL-producing Escherichia coli urinary isolates in Manitoba

OBJECTIVE: Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli are increasingly common in nosocomial and community settings. Furthermore, fluoroquinolone (FQ) and even multidrug resistance (MDR) appear to be associated with certain ESBL genotypes. The purpose of the present study was to determine which ESBL genotypes are associated with FQ and MDR in E coli urinary isolates in Manitoba. METHODS: The authors determined the antimicrobial susceptibility, genetic similarity and ESBL genotype of 27 FQ-resistant and seven FQ-susceptible, ESBL-producing urinary isolates submitted to the clinical microbiology laboratories of two teaching hospitals between October 2000 and April 2005. Susceptibilities to beta-lactams, FQs, trimethoprim-sulfamethoxazole (SXT), doxycycline (DOX), gentamicin (GM) and tigecycline were determined by microbroth dilution; pulsed-field gel electrophoresis (PFGE) was used to determine genetic relatedness, and ESBL genotype was determined by polymerase chain reaction and sequencing. RESULTS: Of 34 ESBL-producing organisms, 27 (79.4%) were found to be ciprofloxacin (CIP) resistant, 27 (79.4%) were SXT resistant, eight (23.5%) were GM resistant and 29 (85.3%) were DOX resistant. Twenty-three (67.6%) had MDR, with concomitant resistance to CIP and SXT; 16 had concomitant resistance to CIP, SXT and DOX; and seven (20.6%) had MDR, with concomitant resistance to CIP, SXT, DOX and GM. All isolates were susceptible to tigecycline. Of 27 FQ-resistant ESBL-producing organisms, seven (25.9%) were genotype CTX-M-14, 19 (70.4%) were genotype CTX-M-15 and one (3.7%) was genotype CTX-M-24. Among the seven FQ-susceptible strains, three (42.8%) expressed SHV-type enzymes, three (42.8%) expressed TEM-type enzymes and one (14.3%) expressed CTX-M-9. CTX-M-15 was the most common MDR-associated genotype. Of a total of 19 strains, 18 (94.7%) were resistant to FQs and SXT; 15 (78.9%) were resistant to FQs, SXT and DOX; and five (26.3%) were resistant to FQs, SXT, DOX and GM. PFGE analysis revealed genetic similarity within CTX-M-15-producing isolates only. CONCLUSION: CTX-M-15 in E coli is strongly associated with an MDR phenotype compared with other genotypes. CTX-M-14 is associated with FQ resistance only. PFGE suggests clonality of CTX-M-15-producing isolates within and among hospitals.     

产气肠杆菌、阴沟肠杆菌、沙雷菌AmpC酶检测及耐药性分析

目的：通过检测阴沟肠杆菌、产气肠杆菌、沙雷菌去阻遏持续高产AmpC酶和超广谱β－内酰胺酶（ESBL）及其耐药性分析，揭示其主要耐药机制，指导临床合理用药。方法：采用改良的酶提取物三维试验法，在常规NCCLS纸片扩散法基础上接种大肠杆菌ATCC25992，在头孢西丁和头孢曲松药敏纸片周围放射性切出琼脂小槽，待测菌的粗酶提取物在槽内扩散，分别进行AmpC和ESBL测定。结果：阴沟肠杆菌、产气肠杆菌、沙雷菌AmpC酶检出率分别为21．4％、0％、45．5％；AmpC酶＋ESBL分别是10．7％、0％、45．5％。它们对青霉素类、一、二、三代头孢菌素类、头霉素类、单环β－内酰胺类、氟喹诺酮类、磺胺类及一些酶抑制剂复合抗生素耐药率60％－90％不等。哌拉西林／他唑巴坦、头孢他啶、头孢吡肟耐药率小于50％。亚胺培南未检出耐药菌株。结论：AmpC酶及AmpC酶＋ESBL的检出以沙雷菌最高、阴沟肠杆菌次之、产气肠杆菌未检出；临床经验用药可选用碳青霉烯类如亚胺培南四代头孢菌素如头孢吡肟、复合抗生素如哌拉西林／他唑巴坦。     

ESBL菌株的检测及临床意义

目的：了解产超广谱β-内酰胺酶（FSBL）菌株在本地区的分离、分布情况，以利于对产ESBL细菌的监控与治疗。方法：双纸片协同试验（DDST）检测ESBL；K－B法药敏试验。结果：6种常见革兰氏阴性（G^-)菌产ESBL总阳性率（14．5％），以阴沟肠杆菌最高（43．2％）；产ESBL细菌来自痰标本最高（57．4％）；病房中神经科病房分离的产ESBL阳性率最高（39．5％）。其中大肠埃希氏菌、阴沟杆菌、肺炎克雷伯菌对头孢噻肟、头孢曲松、氨曲南的体外耐药率达90％－100％，对头孢他啶耐药率为47％－78％；不产ESBL菌株对此四种药物的耐药率明显偏低（P＜0．05）。大肠、肺炎、阴沟杆菌对氨基糖甙类、氟喹诺酮类、磺胺类的耐药性显著高于非产ESBL菌株（P＜0．05）。其他菌株（不动、嗜麦芽、铜绿）由于菌株数太少，无统计学意义，进一步研究应做长期统计。结论：DDST可以快速准确的检测出产ESBL菌株；三代头孢的长期和大量应用是产生ESBL菌的主要原因，应用亚胺培南治疗产ESBL细菌引起的感染效果最佳。     

分离临床细菌性感染患者1320株细菌分析及其药物敏感趋势监测

[目的]了解临床细菌性感染患者细菌感染的流行趋势和对其药物敏感趋势进行监测，为临床合理用药提供依据。[方法]通过对2004年1月1日～2004年12月31日，东方医院临床细菌性感染患者的标本中分离出的1320株病原菌进行凋查分析和对其药物敏感趋势进行监测。[结果]东方医院临床细菌感染患者的标本中共分离出1320株细菌。东方医院临床细菌感染患者的病原性细菌的分布情况及主要致病菌依次为：大肠埃希菌234株，占19.02％；铜绿假单胞菌120株，占9.76％；肺炎克雷伯菌81株，占6.59％；醋酸钙-鲍蔓复合不动杆菌69株，占5.61％；阴沟肠杆菌67株，占5.45％。在东方医院临床细菌感染患者的标本中分离出的1320株细菌中，200株大肠埃希菌中共测得产超广谱β-内酰氨酶（ESBLs）株80株，产酶率40％，在76株肺炎克雷伯菌中共测得ESBLs产酶株18株，产酶率24％；43株金黄色葡萄球菌中共测得耐甲氧西林的金黄色葡萄球菌（MRSA）株18株，产酶率43％；多重耐药现象严重。[结论]临床细菌耐药严重，应根据细菌检验结果合理用药。     

Antimicrobial activity against strains of Escherichia coli and Klebsiella spp. with resistance phenotypes consistent with an extended-spectrum β-lactamase in Europe

Extended-spectrum β-lactamases (ESBLs) have continued to evolve after their initial detection in Europe nearly two decades ago. The summary results from the MYSTIC Program (31 medical centers) were utilized to assess the extent of ESBL occurrence in Europe from 1997 to 2000. ESBL phenotype rates in Klebsiella spp. (32.8%) and Escherichia coli (14.4%) were generally stable, but extensive hospital-to-hospital and unit-to-unit variations were noted. The highest ESBL rates were found in eastern Europe (including Turkey) and in intensive care unit patient populations. Carbapenems remained active against the ESBL-producing strains (meropenem MIC₉₀, 0.25–1 mg/L), while some other agents, such as aminoglycosides, fluoroquinolones, and piperacillin–tazobactam, were significantly less effective. International surveillance initiatives should be maintained to monitor future progression of this important resistance.     

Activity of tigecycline against clinical isolates of Staphylococcus aureus and extended-spectrum beta-lactamase-producing Escherichia coli in Granada, Spain

We evaluated the in vitro activity of tigecycline using the Etest and disk diffusion method according to Clinical and Laboratory Standards Institute guidelines against clinical isolates of methicillin-susceptible Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA) as well as for CTX-M-9 extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and SHV ESBL-producing E. coli. All isolates were susceptible to tigecycline according to US Food and Drug Administration cut-off points. There were no differences in the activity of tigecycline between MSSA and MRSA isolates or between the presence of either type of ESBL. For each type of microorganism studied, we established the equation relating the minimum inhibitory concentration to the diameter of the zone of inhibition.