大肠埃希菌对氨基糖苷类抗生素的耐药谱及其产ESBLs的研究

目的了解临床分离的54株大肠埃希菌对氨基糖类苷类抗生素的耐药谱及产ESBLs情况,分析氨基糖苷类修饰酶AAC(3)-II的检出率及该酶的一些特征。方法采用MIC法测定临床分离的54株大肠埃希菌对7种氨基糖苷类抗生素的耐药谱,用NCCLS推荐的酶抑制剂增强纸片扩散法检测产ESBLs菌株,并通过聚合酶链反应、克隆测序和测定重组菌耐药谱对aac(3)-II基因进行研究。结果54株大肠埃希菌对阿米卡星、庆大霉素、卡那霉素、妥布霉素、链霉素、大观霉素和奈替米星的耐药率分别为14.8%、77.8%、59.3%、66.7%、68.5%、61.1%、22.2%;共检测出产ESBLs菌株34株,占63.0%;aac(3)-II基因在54株大肠埃希菌中检出率为88.5%;质粒转化菌产ESBLs且同时检出aac(3)-II基因。重组菌BL21(DE3)/pET26::aac(3)-II对庆大霉素和卡那霉素有耐药性,对其余5种氨基糖苷类抗生素没有表现出耐药性。结论大肠埃希菌对庆大霉素的耐药率最高,对阿米卡星的耐药率最低;耐氨基糖苷类抗生素的大肠埃希菌与其产ESBLs有相关性;重组菌BL21(DE3)/pET26::aac(3)-II仅对庆大霉素和卡那霉素产生耐药。     

In vitro activity of dactimicin and other aminoglycosides against bacteria producing aminoglycoside-modifying enzymes

Dactimicin is a new pseudo-disaccharide aminoglycoside, originally isolated from cultures of Dactylosporangium matsuzakienzae sp. nov., which is chemically related to astromicin. In this study the in vitro activity of dactimicin has been determined against strains of bacteria producing characterized aminoglycoside-modifying enzymes and has been compared with that of gentamicin, tobramycin, netilmicin and amikacin. Minimum inhibitory concentrations were determined using an agar incorporation technique in Mueller-Hinton agar with an inoculum of approximately 10(4) cfu. Dactimicin was resistant to inactivation by a number of different acetyltransferases (AAC), produced by species of the Enterobacteriaceae, most of which inactivated gentamicin, tobramycin and netilmicin. The exception was an AAC(3')-I produced by an isolate of Escherichia coli, which inactivated gentamicin and dactimicin but not tobramycin, netilmicin and amikacin. Dactimicin was inactivated by the adenyltransferases (AAD) AAD(2") and AAD(9), produced by Pseudomonas aeruginosa, but not by an AAD(4')(4"), produced by a strain of Staphylococcus aureus, nor by an AAD(2") produced by a strain of E. coli. Dactimicin was inactivated by a combination of a phosphotransferase (APH) APH(2") and an AAC(6') produced by strains of S. aureus. The results suggest that dactimicin may retain useful antibacterial activity against many gentamicin-resistant strains of bacteria belonging to the Enterobacteriaceae and some gentamicin-resistant strains of S. aureus.     

Comparison of the antibacterial activity of amikacin (BB-K8) with other aminoglycosides against pathogens recently isolated from clinical materials (author's transl) ]

We determined the antibacterial activity of amikacin against 1,277 strains of pathogenic bacteria isolated from clinical materials during 1974, including beta hemolytic streptococci, pneumococci, enterococci, Staphylococcus aureus, Staph. epidermidis, Escherichia coli, Klebsiella, Enterobacter, Citrobacter, Serratia, Proteus morganii and Pseudomonas aeruginosa, and compared the minimum inhibitory concentration (MIC) of this drug with gentamicin, dibekacin, tobramycin and kanamycin. 1)Antibacterial activity of amikacin against beta hemolytic streptococci, pneumococci and enterococci was as weak as the other four aminoglycosides, but against Staph. aureus, Staph. epidermidis, various groups of Enterobacteriaceae and Pseudomonas aeruginosa showed amikacin the good antibacterial activity as gentamicin, dibedacin and tobramycin, and also showed the good activity against kanamycin resistant strains. 2) Amikacin has the similar antibacterial spectrum as gentamicin, dibekacin or tobramycin, but its antibacterial activity is generally weakest among these four drugs. 3) On many strains tested the cross resistance is observed between amikacin and one of gentamicin, dibekacin and tobramycin, but several strains of Proteus morganii and Pseudomonas aeruginosa which have rather large MIC against gentamicin, dibekacin or tobramycin showed rather small MIC against amikacin.     

Antimicrobial activity of cefotiam combinations against Enterobacteriaceae moderately susceptible or resistant to this new cephalosporin

The interaction of cefotiam with each of the four aminoglycosides gentamicin, tobramycin, netilmicin and amikacin were studied by the broth microdilution method ("checkerboard" technique) against 36 strains of Enterobacteriaceae chosen for their moderate susceptibility (MIC: 4-32 mg/l) or resistance (MIC: 64-512 mg/l) to cefotiam. A high rate of synergistic combinations was found with all the aminoglycosides: 81% with gentamicin, 76% with amikacin, 67% with tobramycin and netilmicin. The therapeutic value of these interactions appeared excellent.     

The enzymatic mechanisms of resistance to aminoglycoside antibiotics in methicillin-cephem-resistant Staphylococcus aureus

We investigated enzymatic mechanisms of resistance to aminoglycoside antibiotics in methicillin-cephem-resistant Staphylococcus aureus (MRSA) by elucidation of the structures of the enzymatic reaction products. According to the MIC data, MRSA, (46 strains) can be classified into 3 groups as follows. 1. Group I (35 strains) was highly resistant to gentamicin (GM) and tobramycin (TOB), and produced 2"-aminoglycosides phosphotransferase (APH (2"]. 2. Group II (8 strains) was sensitive to GM, but was highly resistant to TOB, and produced 4'-aminoglycosides adenylyl-transferase (AAD (4']. 3. Group III (3 strains) was sensitive to GM and TOB, but was highly resistant to kanamycin, and produced 3'-aminoglycosides phosphotransferase (APH (3']-III. Arbekacin (HBK) was the most stable antibiotic to all of the inactivating-enzymes produced by MRSA, and all MRSA were sensitive to HBK.     

R-plasmid mediated transfer of beta-lactam resistance in Bacteroides fragilis

We described plasmid mediated transfer of resistance to beta-lactam antibiotics between Bacteroides fragilis strains. Ampicillin-resistance was transferred from B. fragilis strain GAI-10150 to a B. fragilis strain JC-101 with a frequency of 10(-6)/input donor by a filter mating technique. A common plasmid band, named pBFKW1, was found in both the donor and the transconjugants. The plasmid was purified by an ethidium bromide-CsCl ultracentrifugation. The molecular size of the plasmid pBFKW1 which seemed to encode the beta-lactam resistance and beta-lactamase production was estimated ca. 40 kb by the analysis of endonuclease digest. Substrate profile of the enzymes derived from the donor and a transconjugant were of cephalosporinase character.     

鲍曼不动杆菌环丙沙星耐药性接合转移的实验研究

目的:探讨质粒转移与鲍曼不动杆菌环丙沙星(CIP)耐药性的关系。方法:将鲍曼不动杆菌CIP耐药菌株(供体菌)与E.coli(C600SMRLac-)(受体菌)进行接合试验,采用琼脂稀释法测定供体菌及接合子的CIPMIC值。结果:16株CIP耐药性鲍曼不动杆菌,其中5株CIP耐药株与受体菌成功发生了接合,CIP耐药性接合转移的发生率为31.25%(5/16)。接合子的CIPMIC值比受体菌增加了30～500倍,其中1株接合子对CIP呈现低水平耐药。结论:部分鲍曼不动杆菌的CIP耐药性与质粒有关,且能够通过接合方式在细菌之间发生转移。     

奇异变形菌中整合子分布及耐药性分析

目的 了解院内奇异变形菌中各类整合子的携带分布情况、阳性菌株可变区基因盒类型以及其与宿主菌耐药表型的相关性,从而为临床治疗和院内感染控制提供参考。方法 采用PCR扩增和琼脂糖凝胶电泳等方法,将本院2016年1月—2018年12月份从临床标本中分离得到的150株奇异变形菌进行第1、2和3类整合子的筛选,并对整合子阳性菌株可变区进行测序分析以及宿主菌的耐药性进行相关性分析。结果 150株奇异变形菌中携带整合子的菌株共有91株,阳性率为60.7%,其中第1类整合子阳性菌株有30株,占20.0%;第2类整合子阳性菌株22株,占14.7%;同时携带第1和2类菌株39株,占26.0%;未筛出第3类整合子;在91株整合子阳性菌株中,86株可变区出现扩增产物条带,其余5株可变区未见扩增产物;第1类整合子阳性菌株可变区携带的耐药基因盒主要为AadA2、DfrA32,第2类整合子阳性菌株可变区携带耐药基因盒主要为DfrA1;可变区携带AadA2的菌株对庆大霉素和妥布霉素的耐药率显著高于整合子阴性菌株(P<0.01),可变区携带DfrA1或DfrA32的菌株对复方磺胺甲噁唑(即甲氧苄啶/磺胺甲噁唑)的耐药率也明显高于整合子阴性菌株(P<0.01);91株整合子阳性菌株对氨苄西林/舒巴坦、复方磺胺甲噁唑、环丙沙星、庆大霉素、头孢曲松、妥布霉素和左氧氟沙星的耐药率均显著高于整合子阴性菌株(P<0.01)。结论 临床分离的奇异变形菌携带整合子的比例较高,其可变区所携带的耐药基因主要为编码氨基糖苷类和甲氧苄氨嘧啶类抗菌药物的基因,整合子的携带与宿主菌产生的耐药性呈高度相关。     

奇异变形菌中整合子分布及耐药性分析

目的 了解院内奇异变形菌中各类整合子的携带分布情况、阳性菌株可变区基因盒类型以及其与宿主菌耐药表型的相关性,从而为临床治疗和院内感染控制提供参考。方法 采用PCR扩增和琼脂糖凝胶电泳等方法,将本院2016年1月—2018年12月份从临床标本中分离得到的150株奇异变形菌进行第1、2和3类整合子的筛选,并对整合子阳性菌株可变区进行测序分析以及宿主菌的耐药性进行相关性分析。结果 150株奇异变形菌中携带整合子的菌株共有91株,阳性率为60.7%,其中第1类整合子阳性菌株有30株,占20.0%;第2类整合子阳性菌株22株,占14.7%;同时携带第1和2类菌株39株,占26.0%;未筛出第3类整合子;在91株整合子阳性菌株中,86株可变区出现扩增产物条带,其余5株可变区未见扩增产物;第1类整合子阳性菌株可变区携带的耐药基因盒主要为AadA2、DfrA32,第2类整合子阳性菌株可变区携带耐药基因盒主要为DfrA1;可变区携带AadA2的菌株对庆大霉素和妥布霉素的耐药率显著高于整合子阴性菌株(P<0.01),可变区携带DfrA1或DfrA32的菌株对复方磺胺甲噁唑(即甲氧苄啶/磺胺甲噁唑)的耐药率也明显高于整合子阴性菌株(P<0.01);91株整合子阳性菌株对氨苄西林/舒巴坦、复方磺胺甲噁唑、环丙沙星、庆大霉素、头孢曲松、妥布霉素和左氧氟沙星的耐药率均显著高于整合子阴性菌株(P<0.01)。结论     

Susceptibility of methicillin-resistant Staphylococcus aureus to various antibiotics. Classification by aminoglycoside-modifying enzymes and antibiotics active against MRSA]

MICs of 14 aminoglycoside antibiotics including 10 of those used clinically were determined against 50 strains of methicillin-resistant Staphylococcus aureus (MRSA) which had been isolated at a hospital in Osaka between 1986 and 1990. Arbekacin (ABK) inhibited the growth of all strains at less than or equal to 0.20-6.25 micrograms/ml, showing the most potent activities. Streptomycin showed good activities (1.56-6.25 micrograms/ml) against all strains except one resistant strain (greater than 100 micrograms/ml). Based on susceptibilities to kanamycin (98% resistant), tobramycin (84%), gentamicin (62%), amikacin (36%) and ABK (0%), MRSA strains were classified into 5 types; type 0 producing no aminoglycoside-modifying enzyme, type 1a producing APH(3'), type 1b producing AAD(4', 4'), type 2a producing APH (2')/AAC(6') and APH(3'), and type 2b producing APH(2')/AAC(6') and AAD(4', 4'). In addition to the aminoglycoside antibiotics, 13 known antibiotics including vancomycin (VCM) were found active against MRSA upon random screening. Taitomycin (0.013-0.050 micrograms/ml) was the most potent, and griseoluteins A and B (each 0.10-0.39 micrograms/ml), and macarbomycin (0.05-0.20 micrograms/ml) were more active than VCM (0.39-1.56 micrograms/ml). Novobiocin (less than or equal to 0.20-0.78 micrograms/ml) also showed good activities.     

Sisomicin, netilmicin and dibekacin. A review of their antibacterial activity and therapeutic use

Sisomicin is a naturally occurring aminoglycoside antibiotic produced by Micromonospora inyoensis, while dibekacin and netilmicin are both semisynthetic aminoglycosides. Dibekacin is 3',4'-dideoxykanamycin B and netilmicin is 1-N-ethyl sisomicin. In both cases, these modifications render the agents insusceptible to some of the enzymes found in resistant strains of bacteria which inactivate the parent compounds. Antibacterial activity: All 3 drugs show bactericidal activity against a wide range of Gram-negative bacteria (including E. coli, Enterobacter, Klebsiella and Proteus spp. and Ps. aeruginosa) and also against staphylococci; however, in common with other amino-glycosides, streptococci are usually resistant (except when beta-lactam antibiotics are used in combination) and anaerobic organisms are not sensitive. Sisomicin is closely related structurally to gentamicin Cla, but in vitro studies have shown it to have superior activity to gentamicin against Ps. aeruginosa, closely paralleling the activity of tobramycin, while still possessing the high activity of gentamicin against Serratia and other Gram-negative rods. However, sisomicin is inactivated by virtually all bacterial enzymes which inactivate gentamicin and tobramycin. Nevertheless, it retains useful activity against a number of gentamicin-resistant strains of Ps. aeruginosa which are resistant by non-enzymatic (possibly permeability barrier) mechanisms; in this respect it closely resembles tobramycin. Dibekacin closely resembles tobramycin structurally and in vitro it seems to have a very similar antibacterial spectrum, including activity against some strains of Ps. aeruginosa resistant to gentamicin. Netilmicin has a generally broader antibacterial spectrum than gentamicin, tobramycin, sisomicin or debekacin and is resistant to inactivation by phosphorylating and adenylylating enzymes; however, it is inactivated by all acetylases, apart from acetylase 3-I. Its spectrum is therefore not as wide as that of amikacin against 'gentamicin-resistant' strains. Nonetheless, it is intrinsically more active than amikacin, weight-for-weight, against sensitive strains, apart possibly from Ps. aeruginosa. In fact, its activity against species of the Enterobacteriaceae and staphylococci sensitive to gentamicin is of the same order as the latter and possibly better for Klebsiella-Enterobacter species. All 3 agents show marked antibacterial synergy with a variety of beta-lactam antibiotics against a range of bacteria. Pharmacokinetically, sisomicin, netilmicin and dibekacin all behave like gentamicin. All 3 drugs are excreted in the urine unchanged and have beta-phase elimination half-lives of around 2 to     

The resistance of recent clinical isolates against isepamycin, other aminoglycosides and injectable beta-lactams

Clinical isolates collected from clinical facilities across Japan in 1998 were tested against five aminoglycosides and three beta-lactams. The resistance of 50 strains each of methicillin sensitive Staphylococcus aureus, methicillin resistant Staphylococcus aureus (MRSA), Staphylococcus epidermidis, Escherichia coli, Citrobacter freundii, Klebsiella pneumoniae, Enterobacter sp., Serratia sp., Pseudomonas aeruginosa and Proteus sp. (P. mirabilis 25 strains and P. vulgaris 25 strains) to the aminoglycosides isepamicin (ISP), amikacin (AMK), gentamicin, tobramycin and dibekacin, and to the beta-lactams imipenem, ceftazidime and piperacillin (all three known to be effective against P. aeruginosa) were investigated using a micro liquid dilution method with the following results: 1. ISP was effective against all strains except for 14% of MRSA, 2% of Proteus sp., and 4% of P. aeruginosa. 2. Six strains of MRSA were resistant to all eight drugs; however, in these cases ISP exhibited a relatively low minimum inhibitory concentration (MIC) compared to the other compounds. 3. Four strains of MRSA were resistant to all drugs except ISP. MRSA was the only isolate to demonstrate a resistance to seven or more drugs. 4. Twenty-one strains of MRSA and 1 strain of P. aeruginosa were resistant to six drugs; however, all of these were susceptible to both ISP and AMK. 5. Against all strains tested, ISP generally exhibited a lower MIC compared to AMK. These results suggest that, even ten years after its entering the market, ISP is still an aminoglycoside having a high anti-bacterial activity against a wide range of clinical isolates.     

Gentamicin-susceptibility of various pathogens isolated from clinical materials]

We studied on the antibacterial activity of gentamicin against various pathogens isolated from clinical materials mainly isolated during 1974 and 1975, comparing with other antibiotics. Beta hemolytic streptococci, pneumococci and enterococci are less susceptible to gentamicin than staphylococci. Staph, aureus and Staph. epidermidis resistant to various antibiotics are very susceptible to gentamicin, and no resistant strain to this drug was found. Haemophilus influenzae, H. parainfluenzae and H. parahaemolyticus are very susceptible to gentamicin, and there is no resistant strain to this drug. Escherichia coli, Klebsiella, Citrobacter, Serratia and five species of Proteus are more susceptible to gentamicin and tobramycin than dibekacin and amikacin. A few resistant or less susceptible strains to gentamicin are found in E. coli, Citrobacerr, Serratia, Pr. morganii and Pr. rettgeri. Pr. inconstans is less susceptible to gentamicin than other species of Proteus. Antibacterial activity of gentamicin against Pseudomonas aeruginosa is very strong, but dibekacin and tobramycin are stronger. Gentamicin-resistant strains of Pseudomonas aeruginosa are now rather few.     

鲍曼不动杆菌质粒上氨基糖苷类耐药基因的研究

目的探讨鲍曼不动杆菌(Acinotobacter baumannii)对氨基糖苷类抗生素的耐药性及其耐药机制。方法对71株MDR A.baumanni用VITEK分析仪进行药敏分析,通过PCR和测序探索质粒上的相关耐药基因(aaaCl,aacC2,aacC3,aacA4和armA)。结果 71株A.baumanni对庆大霉素、妥布霉素和阿米卡星的耐药率分别为100%、73%和20%,其中20%的菌株对3种氨基糖苷类抗生素完全耐药,且aaaCl、aacA4和armA基因阳性率分别为100%、100%和84.5%。结论质粒上广泛携带aacCl、aacA4和armA基因是鲍曼不动杆菌对氨基糖苷类抗生素多重耐药的主要机制之一。     

血三株小牛葡萄球菌药敏及耐药机制的初步研究

目的 探讨患者血小牛葡萄球菌（Staphylococcus vitulinus）药敏及耐药机制.方法 用美国BD公司phoenixTM 100全自动细菌鉴定/药敏仪及其NMIC/ID-55鉴定/MIC药敏板对患者血分离的三株小牛葡萄球菌（菌株31937、32612、80708）进行鉴定和21种抗菌药物敏感性检测,应用NMIC/ID-55鉴定/药敏板头孢硝噻吩试验（nitrocefin test,NT）检测其β-内酰胺酶、大环内酯类耐药表型、莫匹罗星高度耐药表型.结果 phoenixTM 100细菌鉴定仪鉴定该三菌均为小牛葡萄球菌,可信度均为90%;3株小牛葡萄球菌药敏结果很相似,均对妥布霉素、阿米卡星、阿莫西林/克拉维酸、复方磺胺、万古霉素、替考拉宁、呋喃妥因、利福平（仅菌株80707耐药）、四环素、利奈唑胺、夫西地酸敏感,对庆大霉素、氨苄西林、青霉素、苯唑西林、红霉素、克林霉素、奎奴普丁、莫匹罗星、莫匹罗星高耐、环丙沙星等药耐药;3株菌NT试验均为阳性、MLSb耐药表型和莫匹罗星高耐.结论 本文这3株小牛葡萄球菌药敏结果均为多耐,其机制推测为产β-内酰胺酶、质粒编码mupA核心基因erm基因.经检索CNKI、CMCC、万方数据医药信息系统和PubMed数据库,本文是我国第一篇研究小牛葡萄球菌耐药机制报道（截止2013年4月9日）.     

2株嗜麦芽寡养单胞菌对β-内酰胺类耐药性的传递

目的了解嗜麦芽寡养单胞菌临床株对抗生素的耐药情况及耐药性的可传递性。方法琼脂纸片扩散法药物敏感试验检测嗜麦芽寡养单胞菌的抗生素耐药情况。接合传递实验获耐药接合株。结果临床菌株H417传递的抗生素耐药性是对头孢噻肟、头孢哌酮、羧苄西林、头孢他啶及庆大霉素；临床菌株A3573传递的耐药性有头孢噻肟、头孢他啶、羧苄西林、氨苄西林／克拉维酸和氨曲南。同时伴有质粒的传递。结论嗜麦芽寡养单胞菌临床株对β-内酰胺类及氨基糖苷类的耐药性可经质粒介导传递：     

Netilmicin Sulfate: A Comparative Evaluation of Antimicrobial Activity,Pharmacokinetics, Adverse Reactions and Clinical Efficacy

Netilmicin, the 1-N-ethyl derivative of sisomicin, is a new aminoglycoside antibiotic that was recently marketed in the United States. Its role in therapeutics is not yet established. The pharmacokinetic profile of netilmicin is very similar to that of gentamicin. Its antimicrobial spectrum and clinical efficacy is similar to that of gentamicin, tobramycin and amikacin. It is less active in vitro against Pseudomonas aeruginosa than gentamicin and tobramycin, but in clinical trials the efficacy of netilmicin against this organism has been similar to other aminoglycosides. Netilmicin is active against some gentamicin and tobramycin-resistant strains of gram-negative bacilli, particularly those harboring adenylating and phosphorylating enzymes. Most of these strains are sensitive to amikacin as well, and amikacin is also active against most netilmicin-resistant strains of these bacteria. Therefore, amikacin remains the aminoglycoside of choice against gentamicin tobramycin and netilmicin-resistant gram-negative bacilli. In comparison to other currently available aminoglycosides, a lower frequency of nephrotoxicity and ototoxicity has been observed in laboratory animals given netilmicin. This has not been unequivocally demonstrated in humans. The frequency of nephrotoxicity in humans has been similar to that of other aminoglycosides. The frequency of ototoxicity associated with netilmicin in humans has been low but not significantly less than with other aminoglycosides, except in one trial. If further studies document a significantly lower frequency of ototoxicity with netilmicin, it may become the aminoglycoside of choice for patients with significant risk factors for ototoxicity, such as advanced age, renal impairment, concomitant ototoxic drug therapy and prolonged aminoglycoside administration.     

Clinical considerations and costs associated with formulary conversion from tobramycin to gentamicin

The clinical and financial effects of replacing tobramycin with gentamicin on the formulary of a 550-bed teaching hospital were studied. On the recommendation of the pharmacy and therapeutics committee, the formulary aminoglycoside was changed from tobramycin to gentamicin in June 1985; the nonformulary status of amikacin was unchanged. Five weeks later, physician compliance was assessed and the reasons for prescribing nonformulary aminoglycosides were determined. Two four-month-long evaluations were done at 6 and 18 months after implementation to assess patterns of use of nonformulary aminoglycosides. The impact on costs was determined after one and two years by considering use patterns of formulary and nonformulary aminoglycosides, as well as those of third-generation cephalosporins and mezlocillin. Resistance patterns of two gram-negative organisms, Pseudomonas aeruginosa and Serratia marcescens, were assessed for 1982-1987. Finally, the rate of nephrotoxicity in gentamicin-treated patients was determined. During the first five weeks after the formulary conversion, 80.3% (106 of 132) of the aminoglycoside orders received were for gentamicin. After telephone follow-up by the pharmacy department, that figure rose to 93.9%. During the four-month reviews beginning at 6 and 18 months, nonformulary orders accounted for 10.9% and 7.4%, respectively, of the total number of courses of aminoglycosides prescribed. In the majority of these cases, tobramycin and amikacin were used to treat infections caused by organisms with documented resistance to gentamicin or to gentamicin and tobramycin, respectively. No clear-cut changes in resistance patterns for Ps. aeruginosa or S. marcescens could be associated with the formulary conversion.(ABSTRACT TRUNCATED AT 250 WORDS)     

肺炎克雷伯杆菌对氨基糖苷类耐药机制的研究

目的了解肺炎克雷伯杆菌对氨基糖苷类药物的耐药情况,同时进行基因分型,确立耐药基因的位点和种类,进一步研究不同基因型对庆大霉素、阿米卡星、奈替米星、链霉素、妥布霉素的耐药情况以及产超广谱β-内酰胺酶与非产超广谱β-内酰胺酶同基因型的关系。方法收集浙江省人民医院检验医学中心2007年2月至2007年8月分离鉴定菌株31株,采用Kirby-Bauer法测定肺炎克雷伯杆菌对庆大霉素、阿米卡星、奈替米星、链霉素、妥布霉素的敏感性,并采用聚合酶链反应(PCR)及电泳测定技术分析氨基糖苷类修饰酶基因型。结果从浙江省人民医院分离到的31株肺炎克雷伯杆菌对庆大霉素、奈替米星、链霉素的耐药率分别为58.1%、6.5%、61.3%,阿米卡星和妥布霉素都未发生耐药;含一种基因型的有6株,两种基因型的有10株,三种基因型的有8株,四种基因型的有3株;产ESBLs有4株,其中含aac(3)-Ⅱ、aac(6″)-Ⅱ产ESBLs的百分率达75%。结论必须加强对细菌耐药性变迁的动态监测,更好地指导临床合理用药。     

Integron presence in a multiresistant Morganella morganii isolate

A multiresistant strain of Morganella morganii was isolated from a patient affected by several severe pathologies. The isolate was found to be resistant to the following antimicrobials: ampicillin, nalidixic acid, cefalothin, cefoxitin, ceftriaxone, ciprofloxacin, chloramphenicol, streptomycin, erythromycin, gentamicin, novobiocin, penicillin, rifampicin, tetracycline and violet crystal. Mechanisms leading to this multiresistance were studied. Porins of M. morganii multiresistant and wild-type strains were analysed by sodium dodecylsulphate–polyacrylamide gel electrophoresis (SDS–PAGE) and were characterised by their ability to form channels in planar black lipid bilayers. The channels formed by porins from multiresistant and susceptible strains suggested that the porins of the multiresistant strain were not responsible for resistance. A 6.6 kb plasmid (pML2003) was detected, isolated and studied. pML2003 included two integrons. Direct sequencing revealed that one of the integrons contained two cassettes, aminoglycoside adenyltransferase (aadB) and chloramphenicol acetyltransferase (catB3) conferring resistance to aminoglycosides and chloramphenicol, respectively. The second integron contained carbenicillinase (blaP1b) and adenyltransferase (aadA2), which confer resistance to β-lactamases and streptomycin, respectively.