常见非发酵菌的耐药性分析

目的 了解常见非发酵菌的临床分布及耐药情况，指导临床合理使用抗菌药物。方法 2003年1月～2004年12月临床分离的铜绿假单胞菌281株、不动杆菌属190株及嗜麦芽窄食单胞菌63株，用Kirby—Bauer法进行药敏试验。结果 591株非发酵菌中以铜绿假单胞菌（47．5％）、不动杆菌属（32．1％）及嗜麦芽窄食单胞菌（10．7％）为主；主要分布于痰液（62．4％）、皮肤软组织创面分泌物（22．7％）中；耐药性分析显示铜绿假单胞菌对亚胺培南的敏感性最高（92．9％），其它依次为头孢他啶（78．3％）、环丙沙星（78．1％）、头孢吡肟（74．4％）、阿米卡星（70．5％）、哌拉西林-他唑巴坦（70．1％）、头孢哌酮-巴坦（67．9％）、哌拉西林（60．3％）、氨曲南（57．5％）、头孢哌酮（57．1％）、替卡西林-克拉维酸（55．7％）；不动杆菌属对亚胺培南的敏感性也最高（95．7％），其它依次为头孢哌酮-舒巴坦（66．7％）、头孢吡肟（59．3％）、替卡西林-克拉维酸（57．4％）、阿米卡星（55．0％）、哌拉西林-他唑巴坦（51．6％）；嗜麦芽窄食单胞菌对头孢哌酮-舒巴坦的敏感性最高（75．6％），其它依次为头孢他啶（75．5％）、复方磺胺甲嗯唑（74．5％）、替卡西林-克拉维酸（73．7％）、环丙沙星（69．8％）、头孢吡肟（63．4％）、哌拉西林-他唑巴坦（56．8％），对包括亚胺培南在内的其它常用抗菌药物均高度耐药。结论 细菌耐药有一定的地区性，定期对本地区细菌耐药性进行监测，对合理使用抗菌药物、减少耐药菌株的产生和流行有重要的临床指导价值。     

Antimicrobial resistance among clinical isolates of Pseudomonas aeruginosa from patients in a teaching hospital, Riyadh, Saudi Arabia, 2001-2005

Antimicrobial resistance to nine anti-pseudomonal agents (azteronam, ceftazidime, cefepime, piperacillin/tazobactam, imipenem, meropenem, ciprofloxacin, amikacin and gentamicin), the magnitude of multidrug resistance, associated underlying conditions, and mortality among patients with Pseudomonas aeruginosa isolates from King Khalid University Hospital, Riyadh, Saudi Arabia from 2001 to 2005 were determined. The results showed that antimicrobial resistance among P. aeruginosa is gradually increasing for most anti-pseudomonal agents, particularly aztreonam, ceftazidime, piperacillin/tazobactam and imipenem. There were 19 (3%) and 12 (2%) multidrug-resistant (MDR) P. aeruginosa patients in 2004 and 2005, respectively, and MDR P. aeruginosa was more commonly found in non-intensive care unit (ICU) patients. Most MDR isolates were from surgical and diabetic patients. The mortality rate was higher among ICU patients.     

Clinical, microbiologic, and epidemiologic characteristics of Pseudomonas aeruginosa infections in a University Hospital, Malatya, Turkey

BACKGROUND: Pseudomonas aeruginosa strains are generally resistant to many antibiotics, and nosocomial infections because of this species are one of the major problems in many hospitals. Molecular typing provides very useful information about origin and transmission of the strains. The aims of the present study were to investigate clinical and microbiologic characteristics of the nosocomial infections caused by P aeruginosa strains in a medical center and to bring up the cross-transmission level of this opportunistic pathogen in a university hospital by analyzing the clonal relationship among the isolates. METHODS: A total of 105 P aeruginosa strains had been identified among the 80 inpatients in a 1-year period from August 2003 to August 2004. Demographic, clinical, and epidemiologic data of the patients were prospectively recorded. The standardized disk-diffusion method was used to determine resistance of the strains to imipenem, ceftazidime, aztreonam, amikacin, gentamicin, mezlocillin, cefepime, tobramycin, meropenem, ceftriaxone, and ciprofloxacin. Clonal relatedness of the strains was investigated by pulsed-field gel electrophoresis (PFGE). RESULTS: Of the 105 P aeruginosa strains identified, 45 (43%) were isolated from the patients hospitalized in intensive care units. Thirteen patients had repeated pseudomonas infection (total 38 infections/13 patients); 26 of these repeated infections in 9 patients showed the same localization. Half of the patients had at least 1 underlying disease such as burn (48%), chronic illness (32%), and malignancy (20%). Fifty-seven patients (71%) had urinary and/or other catheterization. Urinary tract infection (35%) was the most frequent infection encountered, followed by respiratory tract infection (34%) and sepsis (13%). Resistance to the antibiotics tested was in the 12% to 88% range; amikacin was the most effective and ceftriaxone was the least effective antibiotic. The PFGE typing method showed that 28 of the 80 patients' isolates were clonally related, including 23 indistinguishable or closely related strains (29%), and 5 possibly related strains (6%). Epidemiologic data of the 16 patients (20% of the patients) confirmed a clonal relationship among the strains. Of the 26 isolates of the 9 patients having repeated infection in the same location, 18 (69%) were in the clonally related groups, whereas 11 of the 12 strains isolated from repeated infections on different body sites were clonally different. CONCLUSION: Our results indicated that P aeruginosa infections in our hospital mainly affected the patients hospitalized in intensive care units and those having catheterization, burn, and/or chronic illness. Amikacin was the best antibiotic as far as bacterial resistance was considered. Although lack of major PFGE type confirmed no P aeruginosa outbreak, typing results showed that cross transmission and treatment failure are the 2 main problems, which should be consider together to prevent this bacterial infection in medical centers.     

新生儿铜绿假单胞菌耐药性分析

目的：了解新生儿患者临床分离的铜绿假单胞菌耐药情况。方法：采用API细菌鉴定分析系统对2004—2008年湖北省妇幼保健院新生儿住院患者临床分离细菌进行鉴定,并采用Kirby-Bauer法选用13种常用抗菌药物进行体外药物敏感试验。结果：354株铜绿假单胞菌主要来源于痰和胃液标本,共占74.6%;其在临床病区分布中以重症监护病房为主,占81.9%。354株铜绿假单胞菌对环丙沙星、阿米卡星、头孢他啶、头孢吡肟、哌拉西林/他唑巴坦、头孢哌酮/舒巴坦、亚胺培南和美罗培南的敏感率较高,均〉80%;而对哌拉西林、美洛西林、头孢噻肟、头孢哌酮、氨曲南的敏感率则次之。354株铜绿假单胞菌中多重耐药菌占25.7%,且有逐年增多的趋势。结论：铜绿假单胞菌是引起新生儿医院感染的最常见病原菌之一,对抗菌药物呈多重耐药,临床治疗应结合新生儿患者的特点合理选用抗菌药物,以减少耐药株的出现与扩散。     

In vitro susceptibility of Pseudomonas aeruginosa from bacteremic and fibrocystic patients to four quinolones and five other antipseudomonal antibiotics

The in vitro antibacterial activities of 4 quinolones, 4 antipseudomonal beta-lactam antibiotics and tobramycin were determined by an agar dilution technique against 206 clinical isolates of Pseudomonas aeruginosa. 176 isolates derived from blood cultures (BC), the remaining 30 were piperacillin-resistant strains from sputum of cystic fibrosis (CF) patients. The CF strains were more resistant to all drugs tested and differed greatly in susceptibility pattern from the BC strains. Ciprofloxacin, ofloxacin and tobramycin were the most active drugs against the CF strains. More than 80% of the BC strains were susceptible to piperacillin and cefsulodin and more than 90% to ceftazidime, tobramycin, ciprofloxacin and ofloxacin. On a weight basis ciprofloxacin was the most active drug in both groups of strains. Our in vitro data suggest that several valuable drugs are now available in the treatment of infections caused by P. aeruginosa strains not previously exposed to antipseudomonal agents.     

Epidemiology and clinical outcomes of patients with multiresistant Pseudomonas aeruginosa.

We conducted a case-series study of multiresistant Pseudomonas aeruginosa in patients who did not have cystic fibrosis. Patient characteristics, antibiotic exposures, time course of emergence of resistance, and clinical outcomes were examined. Twenty-two patients were identified from whom P. aeruginosa resistant to ciprofloxacin, imipenem, ceftazidime, and piperacillin was isolated. Nineteen (86%) had clinical infection. Patients received prolonged courses of antipseudomonal antibiotics before isolation of multiresistant P. aeruginosa. Nine of 11 patients with soft-tissue infection exhibited resolution of clinical infection but usually required surgical removal of infected tissue with or without revascularization. Overall, three patients died. In two instances in which multiple isolates with different susceptibility profiles from the same patient were available, pulsed-field gel electrophoresis profiles of serial isolates were indistinguishable or closely related. This study illustrates that multiresistant P. aeruginosa emerges in a stepwise manner after exposure to antipseudomonal antibiotics and results in adverse outcomes.     

In vitro activities of antibiotic combinations against clincal isolates of Pseudomonas aeruginosa

Combination therapy has been recommended to treat Pseudomonas aeruginosa infections worldwide. The purpose of the present study was to determine the in vitro activities of piperacillin, cefepime, aztreonam, amikacin, and ciprofloxacin alone and in combination against 100 clinical isolates of P. aeruginosa from one medical center in southern Taiwan. The combination susceptibility assay was performed using the checkerboard technique. The percentage of resistance of P. aeruginosa to single agents in our study was relatively high for the Asia-Pacific area, except to aztreonam. Piperacillin plus amikacin exhibited the highest potential for synergy (59/100) in this study. Moreover, a high percentage of synergism was also noted with amikacin combined with cefepime (7/100) or aztreonam (16/100). The combination of two beta-lactams, such as cefepime with piperacillin, and aztreonam with cefepime or piperacillin, showed synergistic effects against some P. aeruginosa isolates. Although ciprofloxacin is a good anti-pseudomonal agent, a very low potential for synergy with other antibiotics was demonstrated in this study. No antagonism was exhibited by any combination in our study. Among piperacillin-resistant strains, there was synergy with a beta-lactam plus amikacin, including the combination of piperacillin and amikacin. However, the combination of two beta-lactams, such as piperacillin and cefepime or aztreonam, did not have any synergistic activity against these strains. In summary, the combinations of amikacin with the tested beta-lactams (piperacillin, aztreonam, cefepime) had a greater synergistic effect against P. aeruginosa, even piperacillin-resistant strains, than other combinations. Understanding the synergistic effect on clinical strains may help clinicians choose better empirical therapy in an area with high prevalence of multidrug-resistant P. aeruginosa.     

健康肉鸡高比率携有多重耐药铜绿假单胞菌

摘要： 目的 为了解健康成年肉鸡中铜绿假单胞菌的流行情况及其抗生素抗菌谱。方法 2011年1月~3月在河南省洛阳市两个菜市场随机抽取市售健康肉鸡鸡肠内容物,经SCDLP液体培养基增菌,菌液十六烷基三甲基溴化铵琼脂培养基培养,分离细菌经氧化酶试验、绿脓菌素测定、明胶液化试验、42℃生长试验和硝酸盐还原产气试验等一系列试验鉴定,鉴定的铜绿假单胞菌采用K-B法测定对头孢他啶、头孢吡肟、头孢哌酮、羧苄西林、氨曲南、庆大霉素、阿米卡星、妥布霉素、氯霉素、四环素、诺氟沙星、环丙沙星的耐药性。结果 20个样品9个分离出11株铜绿假单胞菌。11株细菌具有7种耐药模式;3种模式为多重耐药模式,共6株细菌,来源6只肉鸡。结论 45%肉鸡携带铜绿假单胞菌,30%肉鸡携有多重耐药铜绿假单胞菌。     

Assay for integrons and pattern of antibiotic resistance in clinical Escherichia coli strains by PCR-RFLP in Southern Iran

The purpose of this study was to determine the prevalence of multidrug-resistant Escherichia coli in clinical specimens. In addition, the existence of integrons in resistant isolates was assessed by amplification of intergase genes. Susceptibility of 200 isolates from five Shiraz hospitals and health centers to 13 antibiotics was determined by the Kirby-Bauer disk diffusion method. The majority of the bacteria were isolated from urine (70.5%) and stool (25.5%) specimens. Antibiotic resistance patterns were observed as follows: amoxicillin 63%, tetracycline 57.5%, co-trimoxazole 48%, cephalotin 40%, nalidixic acid 36%, ciprofloxacin 21%, nitrofurantoin 25%, norfloxacin 20.5%, gentamicin 18%, chloramphenicol 18%, ceftazidime 14%, amikacin 8.5% and imipenem 2%. Of 200 isolates tested, 165 (82.5%) were multidrug resistant. The frequency of multidrug resistance to more than 5 antibiotics was 24.2%. The existence of integrons was confirmed in 44.8% of isolates. Significant association between resistance to gentamicin, amikacin, cephalotin, nalidixic acid, ciprofloxacin, norfloxacin and co-trimoxazole with the existence of integrons was obtained by the PCR-RFLP method. These results showed that integrons may be partly responsible for multidrug resistance. Imipenem, amikacin and ceftazidime were the most effective antibiotics in vitro; however, the clinical efficacy of these antibiotics remains to be assessed.     

Occurrence and antimicrobial resistance pattern of inpatient and outpatient isolates of Pseudomonas aeruginosa in a Saudi Arabian hospital: 1998-2003.

OBJECTIVES: The objective of this study was to describe the pattern and trends of antibiotic resistance of Pseudomonas aeruginosa over a six-year period in a Saudi Arabian hospital. METHODS: This was a retrospective study of the antibiotic resistance of outpatient and inpatient isolates of P. aeruginosa. Only one isolate per patient per year was included in the study. RESULTS: During the study period a total of 2679 isolates of P. aeruginosa were available for analysis. Outpatient isolates constituted 48% of the total number, and of these 23.4% were obtained from wound cultures. For the inpatient isolates, 33.6% and 30% were obtained from the respiratory tract and wounds, respectively. There was no significant increase in the resistance rates of outpatient isolates to the tested antibiotics over time. On the other hand, inpatient isolates showed a statistically significant increase in resistance rates to piperacillin, ceftazidime, imipenem, and ciprofloxacin (p<0.001). Over the study period, the resistance rates of outpatient and inpatient isolates to piperacillin, ceftazidime, imipenem, and ciprofloxacin were 4.6% and 11.5%, 2.4% and 10%, 2.6% and 5.8%, and 3% and 6%, respectively. Gentamicin demonstrated the highest resistance among all tested aminoglycosides for outpatient isolates (6%) and inpatient isolates (6.7%). Resistance to more than two classes of antibiotics was present in 1-2% of inpatient isolates and in 0% of outpatient isolates. CONCLUSION: Antibiotic resistance continues to be a problem especially in inpatient isolates and is likely to be related to increased antibiotic use. Thus, continued monitoring of antibiotic resistance is of great importance to ensure the proper use of antibiotics and to detect any increasing trends in resistance.     

Antibiotic resistance patterns during aminoglycoside restriction

When amikacin first became available its use was restricted to prevent the emergence of resistant strains of gram-negative bacilli to this new agent. Gentamicin was the aminoglycoside most widely used at this time, and the incidence of gentamicin-resistant bacteria was 14%, while only 2.4% were resistant to amikacin. For a period of 15 months gentamicin use was restricted, and amikacin was used almost exclusively. Amikacin use was associated with a fall in the incidence of gentamicin-resistant bacteria to 9.2% (p less than .00005), while amikacin resistance remained unchanged at 2.2% (NS). During a period of 21 months after all aminoglycoside restrictions were lifted, gentamicin use again increased, and was accompanied by a return of gentamicin resistance to the baseline level of 15.3%. During this period, amikacin resistance also increased to 4.0% (p less than .0000001) but was due primarily to an increase in resistant Pseudomonas aeruginosa. Escherichia coli was the most frequently isolated gram-negative bacillus during all three periods, and it remained sensitive to both antibiotics regardless of the drug in use. In contrast, P. aeruginosa showed a high level of resistance to gentamicin, which fell when this antibiotic was restricted, only to return to a high level with reinstitution of gentamicin. While there was also an increase in amikacin resistant strains of P. aeruginosa with unrestricted aminoglycoside use, there was no apparent shift in the pattern of aminoglycoside modifying enzymes among a small random selection of amikacin-resistant bacteria. Impaired uptake of antibiotic was the predominant mechanism responsible for P. aeruginosa resistance among strains that did not produce aminoglycoside acetyltransferase (AAC)(6').     

铜绿假单胞菌耐药性分析及分子流行病学研究简

目的 分析铜绿假单胞菌（PA）耐药现状及耐药基因情况.方法收集2009~2012年临床分离的PA 305株.K-B法进行药敏试验,并检出产ESBLs菌株及耐碳青霉烯的PA,用聚合酶链反应（PCR）对产ESBLs菌株进行TEM、SHV、CTX-M基因检测,对耐碳青霉烯PA进行VIM、IPM、OXA-23基因检测.结果 3年中PA对亚胺培南、美罗培南、头孢他啶、左氧的耐药率呈上升趋势,氨曲南、阿米卡星的耐药率呈下降趋势,305株PA中共检出48株产ESBLs,57株耐碳青霉烯.PCR检测出5株PA含TEM基因,2株含SHV基因.CTX-M、VIM、IPM、OXA-23基因检测均为阴性.结论 产ESBLs是我院耐药PA的重要原因,耐碳青霉烯的PA不含VIM、IPM、OXA-23基因.     

Incidence, etiology, and antibiotic resistance patterns of gram-negative microorganisms isolated from patients with ventilator-associated pneumonia in a medical-surgical intensive care unit of a teaching hospital in istanbul, Turkey (2004-2006)

The identification of microorganisms causing ventilator-associated pneumonia (VAP) is important for formulating appropriate therapies. In this study, we report the incidence, etiology, and antibiotic resistance patterns of Gram-negative microorganisms isolated from patients diagnosed with VAP in our medical-surgical intensive care unit (ICU) during the years 2004-2006. VAP was diagnosed by using the clinical criteria of the Centers for Disease Control and Prevention. Antibiotic resistance patterns of isolated microorganisms were defined by standard methods. The VAP incidence rate was 22.6/1,000 ventilator days. The most frequently isolated pathogens were Acinetobacter spp., methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa. Ninety percent of Acinetobacter spp. isolates were resistant to ceftazidime, 64% to imipenem, and 80% to ciprofloxacin. Fifty-nine percent of P. aeruginosa isolates were resistant to ceftazidime, 32% to imipenem, and 62% to ciprofloxacin. Cefoperazone-sulbactam was the most active agent against Acinetobacter spp. In conclusion, the incidence of VAP and the prevalence of multidrug-resistant microorganisms are quite high in our ICU. Comparison of the resistance rates of isolates demonstrates that certain antibiotic agents are more effective than others.     

Pseudomonas aeruginosa: resistance and therapy

Pseudomonas aeruginosa resistance to antimicrobials is an important therapeutic consideration. Antibiotic resistance to P. aeruginosa may be chromosomally or plasmid mediated. Resistance to P. aeruginosa may also be affected by changes in the cellular membrane or intracellular environment. P. aeruginosa is primarily a nosocomial organism that most commonly colonizes respiratory secretions and urine. The selection of an antipseudomonal antibiotic depends on its inherent in vitro activity and its resistance potential. Anti-P. aeruginosa antibiotics with a high-resistance potential include gentamicin, tobramycin, ciprofloxacin, ceftazidime, and imipenem. Anti-P. aeruginosa antibiotics with a low-resistance potential include amikacin, piperacillin, cefoperazone, cefepime, meropenem, and polymyxin B.     

Citywide clonal outbreak of multiresistant Acinetobacter baumannii and Pseudomonas aeruginosa in Brooklyn,NY: the preantibiotic era has returned

BACKGROUND: Carbapenems are important agents for treating nosocomial gram-negative infections. Carbapenem-resistant bacteria have become increasingly problematic in certain regions. This study determined the citywide prevalence and molecular epidemiological features of carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa in Brooklyn, NY. METHODS: All unique patient isolates of A baumannii and P aeruginosa were collected from 15 Brooklyn hospitals from July 1, 1999, through September 30, 1999. Antibiotic susceptibilities, the genetic relatedness of resistant isolates, and the relationship between antibiotic use and resistance rates were determined. RESULTS: A total of 419 isolates of A baumannii and 823 isolates of P aeruginosa were collected. For A baumannii, 53% were resistant to meropenem and/or imipenem, and 12% were resistant to all standard antibiotics. Ribotyping revealed that a single clone accounted for 62% of the samples and was isolated from patients at all 15 hospitals. The rate of carbapenem resistance was associated with cephalosporin use at each hospital (P =.004). For P aeruginosa, 24% were resistant to imipenem, 5% to amikacin, and 15% to 29% to other antipseudomonal agents. Ribotyping revealed that 3 clones accounted for nearly half of the isolates and were shared by most hospitals. CONCLUSIONS: Approximately 400 patients were infected or colonized with carbapenem-resistant A baumannii and P aeruginosa during a 3-month period in 1999. A few strains have spread widely throughout hospitals in this region. The prevalence of resistant A baumannii seems to be correlated with cephalosporin use. Multiresistant hospital-acquired bacteria should be viewed as a serious public health issue rather than an individual hospital's problem. An intensive coordinated effort will be needed to effectively address this problem.     

Antimicrobial resistance of Gram-negative bacilli isolates from inpatients and outpatients at Yaounde Central Hospital, Cameroon.

OBJECTIVE: To determine and compare antimicrobial susceptibility patterns of pathogenic bacteria from inpatients and outpatients at a university teaching hospital in Yaounde, Cameroon. METHODS: Gram-negative bacilli isolates (n = 522), obtained from a wide range of clinical specimens (urine, pus and blood) from inpatients and outpatients at Yaounde Central Hospital between March 1995 and April 1998, were evaluated for resistance to antibiotics (amoxicillin, amoxicillin/clavulanate, piperacillin, cefazolin, cefoxitin, cefotaxime, ceftazidime, aztreonam, imipenem, gentamicin, tobramicin, ofloxacin and trimethoprim/sulfamethoxazole). RESULTS: Of the 522 isolates recorded, 80.3% were Enterobacteriaceae. A high incidence of resistance to amoxicillin (85%), piperacillin (75%) and trimethoprim/sulfamethoxazole (71%) was observed. The proportion of antimicrobial-resistant isolates from inpatients was significantly higher than that from outpatients (P < 0.05), except for piperacillin, tobramicin and trimethoprim/sulfamethoxazole. The combinations of antimicrobial and organism showed that the percentage of ceftazidime-resistant Pseudomonas aeruginosa and ceftazidime-resistant Enterobacter cloacae were 26.8% and 24% respectively. The rate of antimicrobial resistance in isolates from inpatients was not significantly higher than that in isolates from outpatients for all the antimicrobial/organism combinations, except for ceftazidime-resistant Escherichia coli, which was exclusively found in isolates from inpatients. Among Enterobacteriaceae, high and low level penicillinase (mostly in E. coli (13.6% and 11% respectively) and Klebsiella spp. (9% and 8% respectively) were the most important beta-lactam resistance phenotypes (31.2% and 23.6%, respectively). Wild type (exclusively observed in E. coli, Proteus mirabilis and Salmonella spp.) and low level penicillinase were higher in outpatient than inpatient isolates (wild type--17.9% vs 10.8% and low level penicillinase--29.4% vs 20.5%, respectively; P < 0.05). However, extended spectrum beta-lactamase strains (Klebsiella spp. (3.5%), E. coli (2.6%), Citrobacter spp. (0.7%), Enterobacter spp. (0.4%) and P. mirabilis (0.2%)) were exclusively recovered from inpatients. Penicillinase and high level cephalosporinase resistance phenotypes were frequently observed in non-fermenter Gram-negative bacilli (46.6% and 29.1% respectively). However, there were no significant differences in penicillinase and cephalosporinase resistance between inpatient and outpatient isolates. CONCLUSION: As the incidence of antimicrobial resistance is substantially higher in isolates from inpatient than outpatient pathogens, more resources should be allocated within the hospital to encourage good antibiotic practices and good hospital hygiene.     

Analysis of amikacin-resistant Pseudomonas aeruginosa developing in patients receiving amikacin

During a 36-month period, 28 patients treated for infections due to amikacin-susceptible Pseudomonas aeruginosa subsequently developed infections or colonization with amikacin-resistant P aeruginosa at the same site. Eleven amikacin-susceptible/-resistant pairs of isolates were analyzed for aminoglycoside-inactivating enzymes, plasmid profiles, cellular proteins, outer membrane proteins (OMPs), lipopolysaccharide (LPS) profiles, and amikacin uptake. While clearly distinct from isolates of other patients, sensitive and resistant isolates from the same patients were indistinguishable in plasmid profile, LPS profiles, and OMPs. These results suggest that the resistant P aeruginosa isolates were derived from the sensitive isolates. None of the resistant isolates produced enzymes known to inactivate amikacin. In nine of 11 resistant isolates tested, transport of amikacin into P aeruginosa was reduced. A major mechanism of in vivo development of amikacin resistance in P aeruginosa is alteration in permeability to amikacin, but the aquisition of plasmids or changes in OMPs or LPS profile may not account for this phenomenon.     

Resistant rate to antibiotics in Tian Tan Hospital for 3 years]

The resistance to antibiotics of the 985 clinical isolates collected in Tian Tan hospital was studied. The results showed that S. aureus had a resistant rate of more than 90% to penicillin and was also highly resistant to erythromycin. Methicillin resistant Staphylococcus Aureus (MRSA) was isolated in 15.6% of all the isolates with S. aureus. The isolation rate of MRSA is lower than that in other countries or districts of West Pacific Area. K. pneumonia and other Gram negative bacilli had a resistant rate of 0.6% to amikacin and P. aeruginosa was all sensitive to Polymyxin-B.     

Antimicrobial activities and mechanisms of carbapenem resistance in clinical isolates of carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter spp

We tested the antimicrobial activities of meropenem (MEPM), imipenem (IPM), panipenem (PAPM), piperacillin (PIPC), cefepime (CFPM), aztreonam (AZT), amikacin (AMK), and levofloxacin (LVFX) against 106 clinical Pseudomonas aeruginosa isolates and 64 clinical Acinetobacter spp. isolates with reduced susceptibility to carbapenems. Using NCCLS breakpoints, the percentages of P. aeruginosa strains susceptible to AMK and Acinetobacter spp. strains susceptible to LVFX were found to be 51.1% and 55.6%, respectively, which represented the highest activity among 8 antimicrobial agents in each organism. Referring to the correlations among MICs of carbapenems, MEPM showed a higher activity than IPM and PAPM in both organisms; 29 of the 94 strains (30.9%) of IPM-resistant P. aeruginosa were susceptible to MEPM. Further study for resistance mechanisms to carbapenems by the disk diffusion method using 2-mercaptopropionic acid revealed that 8 of the 64 Acinetobacter spp. isolates (12.5%) were metallo-beta-lactamase producers, while none of 106 P. aeruginosa isolates were metallo-beta-lactamase producers. PCR analysis using blaIMP-specific primers confirmed that 4 of the 8 metallo-beta-lactamase-producing Acinetobacter spp. isolates detected by the disk diffusion method were carrying the blaIMP gene. The identification of metallo-beta-lactamase-producing Acinetobacter spp. isolates implies that metallo-beta-lactamase genes have been disseminated among various gram-negative pathogens.     

产超广谱β-内酰胺酶大肠埃希菌及肺炎克雷伯菌的耐药基因序列分析

目的　了解四川大学华西医院产超广谱 β 内酰胺酶 (ESBLs)肺炎克雷伯菌和大肠埃希菌的TEM及SHV型ESBLs亚型 ,并分析其耐药性。方法　采用聚合酶链反应 (PCR)扩增分离四川大学华西医院住院患者的产ESBLs大肠埃希菌与肺炎克雷伯菌株的TEM型及SHV型ESBLs基因并测序 ,用琼脂稀释法测定头孢他啶和头孢噻肟等 8种抗菌药物的最小抑菌浓度 (MIC)值。结果　所有产ESBLs株均耐头孢噻肟 ,11株耐氨曲南 ,2株分别耐头孢他啶和头孢吡肟 ,对环丙沙星、阿米卡星及头孢西丁耐药的分别为 11株、5株和 3株。 12株ESBLs菌中 10株产SHV 2 ,2株产TEM 19。结论　本研究中的产ESBLs株以耐头孢噻肟和氨曲南为主 ,其中绝大多数为多重耐药株 ,产SHV 2和TEM 19是其对头孢噻肟及氨曲南等氧亚胺基 β 内酰胺酶类抗生素耐药的原因之一