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*

Corynebacterium striatum is a commonly isolated contaminant in the clinical microbiology. However, it can be an opportunistic pathogen in immunocompromised and even immunocompetent hosts. The increasing prevalence of C. striatum infection has been associated with immunosuppression and prosthetic devices. We report a case of meningitis with cerebrospinal fluid drainage and a case of catheter-related bloodstream infection caused by C. striatum. The isolates were identified as nondiphtherial Corynebacterium species by VITEK 2 (bioMérieux, France) anaerobe and Corynebacterium card. The final identification by 16S rRNA gene sequencing analysis was C. striatum with 99.7% identity and 99.6% identity with C. striatum ATCC 6940, respectively. Both strains were sensitive to vancomycin and gentamicin, but multidrug-resistant to ciprofloxacin, penicillin, erythromycin and imipenem.
Cerebrospinal Fluid ; Ciprofloxacin ; Corynebacterium* ; Drainage ; Erythromycin ; Genes, rRNA ; Gentamicins ; Imipenem ; Immunosuppression ; Meningitis* ; Penicillins ; Prevalence ; Sepsis* ; Vancomycin

Clinical isolates of Acinetobacter spp. in Korea exhibit higher antimicrobial resistance rates than in foreign countries and frequently show multi-drug resistance. Approximately 67% (272/405) of Acinetobacter baumannii isolates collected from 19 hospitals in Korea in 2008 exhibited intermediate susceptibility or resistance to imipenem and/or meropenem. The most important mechanisms in acquiring carbapenem resistance in A. baumannii in Korea are production of OXA-23 and overproduction of OXA-51, while that in non-baumannii Acinetobacter is the production of metallo-beta-lactamases. All the carbapenem-resistant A. baumannii isolates were identified as clonal complex 92 and belonged to worldwide clone 2.
Acinetobacter ; Acinetobacter baumannii ; Clone Cells ; Drug Resistance, Multiple ; Imipenem ; Korea ; Thienamycins

BACKGROUND: Enterococcus faecium (E. faecium) is potential pathogens of mixed infections for which a broad-spectrum antimicrobial agents such as imipenem has a therapeutic role. But controversy continues concerning testing imipenem versus enterococci. The purpose of this study were 1) to investigate the ability of penicillin and ampicillin minimum inhibitory concentration (MIC) to predict in vitro susceptibility of E. faecium versus imipenem. and 2) to compare MICs of ampicillin, penicillin and imipenem by the Vitek system with those by agar dilution method. METHODS: Fifty-two isolates of E. faecium between April 2002 and May 2002 were tested. Each isolate was tested versus penicillin, ampicillin and imipenem. MICs were determined by Vitek system and agar dilution method according to NCCLS guidelines. Imipenem MIC determinations were repeated by E-test. RESULTS: MIC of Vitek system tends to be lower than that of agar dilution method, but there was good concordance between MICs of penicillin and ampicillin by Vitek system and agar dilution method. But for imipenem, the MICs by the agar dilution method did not correspond with the Vitek results. Of the 52 E. faecium isolates tested, in vitro activity of penicillin and ampicillin accurately predicts that of imipenem. CONCLUSIONS: MICs of ampicillin and penicillin are reliable, but imipenem MIC is not reliable for E. faecium by Vitek system. In vitro activity of penicillin and ampicillin versus E. faecium accurately predicts that of imipenem.
Agar ; Ampicillin ; Anti-Infective Agents ; Coinfection ; Enterococcus faecium* ; Enterococcus* ; Imipenem* ; Microbial Sensitivity Tests ; Penicillins

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

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