No abstract available.
Gram-Positive Cocci* ; Imipenem* ; Ofloxacin*

Minimal inhibitory concentrations (MICs) against piperacillin/tazobactam were determined on a total of 50 clinical isolates of imipenem resistant Pseudomonas aeruginosa (IRPA). MIC50 and MIC90 were 32microgram/mL and 512microgram/mL, respectively. The susceptibility of IRPA against piperacillin/tazobactam was 59%. Of the 50 IRPA strains, only two were PCR positive for blaVIM and none for blaIMP.
Imipenem ; Polymerase Chain Reaction ; Pseudomonas aeruginosa* ; Pseudomonas*

No abstract available.
Acinetobacter baumannii* ; Acinetobacter* ; Hospitals, General* ; Imipenem* ; Korea*

BACKGROUND: In our hospital, an abrupt increase in the resistant rate of A. baumannii to imipenem was observed. We evaluated the imipenem minimal inhibitory concentration (MIC) of an automated system that our laboratory is using, by comparing with those of other methods. METHODS: During the period from February 2002 to February 2003, the imipenem MICs of the agar dilution method, Etest(R), and the disk diffusion method, were compared for imipenem-resistant A. baumannii tested by an automated system in 46 samples at Chung-Ang University Phil-Dong Hospital. We tested for susceptibility to imipenem with the Vitek system by using the GNI card, the disk diffusion method by using the imipenem disk (BBL(TM)), and the agar dilution method. PCR testing of the isolates for carbapenemase genes (IMP-1 and VIM-2) detected in other hospitals was done using published primers and conditions. RESULTS: By the agar dilution method, 23 (50.0%) isolates were susceptible to imipenem, 14 (30.4%) isolates were intermediate, and 9 (19.6%) isolates were resistant. However, by the Etest, 8 (17.4%) were susceptible to imipenem, and 28 (60.9%) isolates were resistant. By the disk diffusion method, the susceptible isolates were 14 (30.4%) and the resistant isolates were 17 (37.0%). Quantitative agreement between the agar dilution method and the disk diffusion test gave an inverse linear correlation coefficient (r=-0.564). The results of the 13 isolates, whose results of the MIC were below 2 or above 16 in the agar dilution method, corresponded with the Etest and the disk diffusion test. The IMP-1 gene was detected in one isolate. CONCLUSIONS: It is recommended that when a gram-negative bacilli isolate including A. baumannii is characterized as resistant to imipenem by the Vitek system, an additional simple test, such as the disk diffusion assay, might be used.
Acinetobacter baumannii* ; Agar ; Diffusion ; Imipenem* ; Polymerase Chain Reaction

BACKGROUND: Multi-drug resistant (MDR) Acinetobacter baumannii has emerged as one of the most important nosocomial pathogens. In addition to the diverse resistance mechanisms, some A. baumannii strains are known to have biofilm-producing capacity, thereby decreasing antibiotic effectiveness. MATERIALS AND METHODS: This study was designed to assess biofilm-producing capacity of three different MDR A. baumannii strains with diverse resistance mechanisms (OXA-51, IMP-1 and VIM-2 type beta-lactamases), and intended to compare the effect of each antibiotic regimen (rifampicin, colistin, imipenem, tigecycline, rifampicin-imipenem and rifampicin-colistin) on mature A. baumannii biofilms using in vitro polystyrene plate biofilm assay. RESULTS: Among three MDR A. baumannii strains, only VIM-2 strain produced strong biofilm compared to the controls (optical density, 8.04 +/- 2.16 vs. 0.49 +/- 0.26). Regarding VIM-2 strains, none of imipenem, colistin and rifampicin reduced biofilm formation alone at MIC of each antibiotic agent (inhibition of biofilm synthesis, less than 30%). In comparison, tigecyclin (0.76 +/- 0.23), imipenem-rifampicin (1.07 +/- 0.31) and colistin-rifampicin (1.47 +/- 0.54) showed a significant inhibition of biofilm synthesis compared to the positive controls at 48 hours after incubation (P<0.01). Tigecycline inhibited biofilm formation even at the one fourth level of MIC (1.17 +/- 0.21). Likewise, both imipenem and colistin were also effective even with the reduced concentrations when those were combined with rifampicin. Such biofilm-inhibiting effects with those antibiotic regimens sustained up to 96 hours after incubation. CONCLUSION: Tigecycline, imipenem-rifampicin and colistin-rifampicin would be effective for the prevention or reduction of biofilm formation caused by A. baumannii strains.
Acinetobacter baumannii* ; Anti-Bacterial Agents ; Biofilms ; Colistin* ; Imipenem* ; Polystyrenes ; Rifampin*

BACKGROUND: Multi-drug resistant (MDR) Acinetobacter baumannii has emerged as a significant infectious agent in hospitals worldwide. The purpose of this study was to determine the molecular characterization of MDR A. baumannii clinical isolates. METHODS: Two hundred eighty-five strains of non-duplicated A. baumannii collected from March to November 2011 from a university hospital laboratory located in the Wonju area of the Gangwon province of Korea were analyzed for MDR genes. RESULTS: All of the 285 imipenem-resistant A. baumannii isolates were encoded by a blaOXA-23-like gene, and all isolates with the blaOXA-23-like gene had the upstream element ISAba1. The 16S rRNA methylase gene armA was detected in 153 (50.2%) clinical isolates, but rmtA, rmtB, rmtC, rmtD and npmA were not detected in any isolates in the present study. The gene encoding aac(6')-Ib was the most prevalent aminoglycoside-modifying enzyme. The sequencing data for the quinolone resistance-determining region of gyrA and parC revealed the presence of Ser (TCA) 83 to Leu (TTA) and Ser (TCG) 80 to Leu (TTG) substitutions. All but one of the 285 A. baumannii isolates showed similar band patterns on repetitive extragenic palindromic-PCR profiles. CONCLUSION: The molecular characteristics of the resistance genes of MDR A. baumannii isolates obtained from the Wonju area of Gangwon province were similar to those of other areas in Korea.
Acinetobacter ; Acinetobacter baumannii ; beta-Lactamases ; Genes, MDR ; Imipenem ; Korea ; Laboratories, Hospital ; Methyltransferases

The present study has been performed to evaluate 20 cardiopathy children and 20 healthy children's oral micorbes at the point of antimicrobial susceptibilities for antimicrobial prophylaxis to prevent bacterial endocarditis. The results were as follows: 1. Both groups had similar oral microbes. 2. The antimicrobial susceptibility of S. viridans were: Penicillin< Oxacillin< Ampicillin< Cephalothin< Erythromycin< Clindamycin< Gentamicin< Ciprofloxacin< Vancomycin=Imipenem. The cardiopathy group was slightly lower antimicrobial susceptibility rates than healthy group. 3. The antimicrobial susceptibility of Neisseriaceae were: Clindamycin< Erythromycin< Vancomycin< Penicillin< Gentamicin< Cephalothin< Ciprofloxacin< Imipenem. The antibiotics of bacterial endocarditis antibiotic prophylaxis regimens for dental procedures according to the American Heart Association were generally lower antimicrobial susceptibilities, so they were considered inadequate for the first selective antibiotics and Imipemem was best suitable antimicrobials. Conclusively, when choose antimicrobials for treatment or antimicrobial prophylaxsis for bacterial endocarditis, surveillant culture must be performed to evaluated personal antimicrobial susceptibilities of intraoral microbes for proper antimicrobial choice for dental procedures.
American Heart Association ; Anti-Bacterial Agents ; Antibiotic Prophylaxis ; Child* ; Endocarditis* ; Endocarditis, Bacterial ; Humans ; Imipenem ; Neisseriaceae

BACKGROUND: Spread of imipenem-resistant Pseudomonas aeruginosa isolates is an important clinical threat. The aim of this study is to survey the prevalence of carbapenem-resistant P.aeruginosa isolates in a university hospital, Busan, Korea, and to determine the mechanisms of the resistance. METHODS: P.aeruginosa isolates from the patients in Kosin University Gospel Hospital were collected during the period of June through September, 2004. Antimicrobial susceptibilities were tested by the disk diffusion method, and production of carbapenemase and metallo-beta-lactamase was determined by the modified Hodge and EDTA-disk synergy tests, respectively. MICs were determined by the agar dilution method, and pIs of beta-lactamases were determined by the isoelectric focusing. Genotypes of carbapenemases were determined by direct sequencing of amplified products. RESULTS: A total of 77 clinical isolates of P.aeruginosa were collected. Twenty-two (55.0%) and 15 (37.5%) isolates showed positive results in the modified Hodge and EDTA-disk synergy tests, re-spectively. Searches for bla OXA-23 and bla IMP-1 genes showed positive results in 15 and 12 isolates, respectively. MIC ranges of imipenem and meropenem to OXA-23-producing isolates were 8-16 microgram/mL and 2-32 microgram/mL, respectively, and those to IMP-1-producing isolates were 2-> or =256 microgram/mL and 2-128 microgram/mL, respectively. CONCLUSION: Production of OXA-23 or IMP-1 is the most prevalent mechanism of imipenem-resistance in P.aeruginosa isolates in a university hospital, Busan, Korea. Periodical surveys are necessary to monitor the spreading of imipenem-resistant isolates and emerging new mechanisms of imipenem-resistance.
Agar ; beta-Lactamases ; Busan ; Diffusion ; Genotype ; Humans ; Imipenem ; Isoelectric Focusing ; Korea ; Prevalence* ; Pseudomonas aeruginosa* ; Pseudomonas*

BACKGROUND: Catheter-related bacteremia is a frequent complication among hemodialysis patients using a tunneled cuffed catheter. The standard therapy of catheter-related bacteremia involves both systemic antibiotics and catheter replacement. This study was performed to evaluate the effect of antibiotic lock therapy in conjugation with systemic antibiotics without catheter removal on catheter-related bacteremia. METHODS: Thirty six chronic hemodialysis patients with tunneled cuffed catheter were monitored for infection between July 2001 and July 2005. We analyzed the efficacy of antibiotic lock protocol compared with systemic antibiotics alone. RESULTS: Twenty-nine episodes of catheter-related bacteremia occurred in 27 patients during the study periods. The incidence of catheter-related bacteremia was 1.5 episodes/1000 catheter-days. A single gram-positive coccus grew in the 16 cases (55.2 %), and gram-negative organisms grew in the 69 cases (31.0%). Sixteen of 18 patients (88.9%) treated with antibiotic lock protocol had successful catheter salvage versus only 6 of the 11 patients (54.5%) treated with systemic antibiotics alone (p=0.05). Three patients with Burkholderia pickettii and a patient with Acinetobactor calcoaceticus-baumannii complex were treated with antibiotic lock protocol with systemic ciprofloxacin and imipenem, respectively. CONCLUSION: This study suggests that antibiotic lock protocol in eradicating catheter-related bacteremia is effective treatment without requiring catheter replacement.
Anti-Bacterial Agents ; Bacteremia* ; Burkholderia ; Catheters ; Ciprofloxacin ; Humans ; Imipenem ; Incidence ; Renal Dialysis

The susceptibilities of 45 clinical isolates of bacteroidis fragilis to cefaclor, ciproflxacin and imipenem were determined by new method, E-test (AB Bidisk, Solna, Sweden) and were compared with those from conventional agar dilution method by using brain heart infusion, Mueller-Hinton and Wilk:..s Chalgren agar plates. And the susceptibility of 60 clinical isolates of bacteroides fragilis group (B. fragilis 45 strains, B. distasonis 6 strains, B. ovatus 5 strains, B. thetaiotaomicron 4 strains) to 5 quinolones (ciprofloxacin, enoxacin, norfloxacin, ofloxacin, pefloxacin) were determined by in vitro agar dilution method. Compared with agar dilution MICs for B. fragilis 45 strains, 90.3% of E-test MICs were within +/- 1 dilution of the agar dilutions, and 98.4% were within 2 dilutions. And there were little effect of different medium bases to determine MICs except Mueller-Hinton agar. On Mueller-Hinton agar, B. fragilis showed have or no growth activity. In vitro susceptibility of B. fragilis group to quinolones, most of the test strains showed resistant patterns to quinolones except ofloxacin and there was little difference of susceptibility patterns between species of B. fragilis group.
Agar* ; Bacteroides fragilis* ; Bacteroides* ; Brain ; Cefaclor ; Enoxacin ; Heart ; Imipenem ; Norfloxacin ; Ofloxacin ; Quinolones