Aeromonas hydrophila infection has been increasingly found, in particular among patients with various underlying diseases. Many characteristics of this organism are quite similar to those of Enterobacteriaceae and Vibrio, making an accurate identification difficult. In a period of 2 years, the authors obtained a total of 27 isolates of A. hydrophila from clinical materials, and their cultural and biochemical characteristics are herewith reported. Some of the most important clues to suspect this organism were a wide zone of complete hemolysis on blood agar, partially alkaline slant, acid butt, and small amount of gas in trip1e sugar iron agar (TSI), weak indole reaction, and negative ornithine decarboxylase in motility indole ornithine medium (MIO), and usually positive citrate utilization. It is concluded that the identification of this organism should be possible on the basis of deoxyribonuclease (DNase), oxidase, and a few other tests. Our isolates showed a similar antibiotic susceptibility to those reported in other countries; i.e., a11 were resistant to ampicillin and most were susceptible to other antibiotics, excluding cephalothin.
Aeromonas/drug effects ; Aeromonas/isolation & purification* ; Aeromonas/physiology ; Antibiotics/pharmacology ; Culture Media ; Human ; Microbial Sensitivity Tests

Enterococci have emerged as a major nosocomial pathogen and as an ever-increasing problem in antimicrobial resistance. They are ubiquitous in the intestinal flora of humans and animals and inherently resistant to a wide array of antimicrobial agents, and, more alarmingly, they seem to have a potential facility for acquiring new resistance determinants, including beta-lactamase production, high-level resistance to aminoglycosides, and recently, glycopeptide resistance. Collectively, all of these properties make enterococci one of most difficult nosocomial pathogens to treat and control today. The purpose of this review was to examine the epidemiology, the mechanisms, and laboratory detection of resistance of enterococci to the two major groups of antibiotics: aminoglycosides and glycopeptides.
Aminoglycosides/pharmacology ; Antibiotics, Glycopeptide/pharmacology ; Drug Resistance, Microbial/physiology* ; Enterococcus/physiology* ; Enterococcus/drug effects ; Epidemiologic Methods ; Human

Hyaluronan (HA), a natural glycoaminoglycan featuring an extracellular matrix, has been suggested as an effective biocompatible material. In this study, the effectiveness of HA microparticles as a carrier system for antibiotics was evaluated, and their physicochemical characteristics were determined. Microparticles were fabricated by the gelation of sulfadiazine (SD) loaded HA solution with calcium chloride through either a granulation (GR-microparticles) or encapsulation (EN-microparticles) process, and atelocollagen was incorporated into the microparticles as an additive in order to improve their physical properties. The characteristics of the microparticles were examined by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and swelling test. In vitro release experiments were performed for 7 days and the released amount of SD was determined using high-performance liquid chromatography (HPLC). Microscopic observations revealed that the collagen incorporated HA particles had a more compact surface than the HA particles. DSC analysis determined a loss of SD crystallinity in the particles. Calcium chloride retarded the swelling of particles, whereas the loaded drug contents did not affect this property. Both GR-and EN-microparticles sustained SD release with initial bursting effect. SD release from EN-microparticles was faster than from GR- microparticles. In addition, the release rate was dependent on the SD content in the microparticles. These results suggest that collagen modified HA microparticles have a potential as a release rate controlling material for crystalline drugs such as SD.
Antibiotics/*administration & dosage ; Calcium Chloride/pharmacology ; Collagen/*pharmacology ; *Drug Carriers ; Hyaluronic Acid/*administration & dosage ; Sulfadiazine/administration & dosage

The emergence of multi-drug resistant gram-positive cocci such as methicillin-resistant (MR) staphylococci, vancomycin-resistant (VR) enterococci, and vancomycin-intermediate resistant S. aureus (VISA) has given new urgency to the development of new antimicrobial agents. One of these is quinupristin/dalfopristin (Q/D). We decided to determine the susceptibility of gram-positive cocci isolated at two university hospitals in Seoul to Q/D and compare the results with eight other antimicrobial agents. We investigated 120 isolates of S. aureus including 49 MRSAs and one VISA, 120 isolates of coagulase negative staphylococci (CNS), 64 E. faecalis and 56 E. faecium, including seven strains of VR E. faecium. Minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) for several antimicrobials, including vancomycin and Q/D, were determined by broth microdilution. All S. aureus including VISA were susceptible to Q/D. Q/D MIC90 for both methicillin-susceptible S. aureus (MSSA) and MRSA was 0.25 g/mL. 49 (87.5%) of 56 E. faecium including six of seven VR E. faecium were susceptible to Q/D. E. faecalis were not susceptible to Q/D (only 1.5% susceptible), but were inhibited by ampicillin (94% susceptible) or vancomycin (95%). CNS was susceptible to Q/D (96% susceptible) and vancomycin (100% susceptible). One of 38 staphylococci and two of 17 E. faecium were tolerant to Q/D. In conclusion, Q/D showed excellent activity against all species of gram-positive cocci including MRSA, VISA, and VR E. faecium except E. faecalis, and may provide a valuable option for the treatment of infections caused by these emerging nosocomial pathogens of gram-positive cocci.
Antibiotics/pharmacology* ; Antibiotics, Peptide/pharmacology* ; Coagulase/analysis ; Enterococcus faecalis/drug effects ; Enterococcus faecium/drug effects ; Human ; Korea ; Microbial Sensitivity Tests* ; Staphylococcus/enzymology ; Staphylococcus/drug effects ; Staphylococcus aureus/drug effects ; Support, Non-U.S. Gov'tn ; Virginiamycin/pharmacology* ; Virginiamycin/analogs & derivatives*

Campylobacter fetus subsp. fetus is a rare human pathogen, but can cause serious extraintestinal infections. Effective antimicrobial agent is required for the therapy, but we have very limited knowledge on the susceptibility of the organism. In this study, the susceptibility of 25 isolates of the organism to 14 antimicrobial agents was tested by an agar dilution method. Antimicrobial agents with low MIC ranges, in micrograms/ml, were: meropenem Y or = 0.25, dirithromycin < or = 0.5, gentamicin > or = 1, amikacin, ofloxacin, tetracycline and erythromycin < or = 2. The MIC range of cefepime was 0.5-8 micrograms/ml, but those of other beta-lactams were relatively high. All of the isolates were interpreted to be susceptible to cefepime, meropenem, amikacin, gentamicin, ofloxacin, tetracycline and dirithromycin. A significant proportion of the isolates were either intermediate or resistant to ampicillin, cephalothin, cefotaxime, aztreonam, loracarbef and erythromycin. In conclusion, the organism remains susceptible to aminoglycosides and tetracycline. Greater in vitro activity of meropenem, ofloxacin and dirithromycin require clinical evaluation.
Antibiotics/*pharmacology ; Blood/*microbiology ; Campylobacter fetus/*drug effects/isolation & purification ; Human ; Microbial Sensitivity Tests ; Synovial Fluid/*microbiology

We performed an in vitro cell culture experiment to ascertain whether rifampin exhibits bactericidal effects against Orientia tsutsugamushi, the causative agent of scrub typhus. ECV304 cells were infected with the Boryong or AFSC-4 strain of O. tsutsugamushi and then, the cultures were maintained in media with increasing concentrations of rifampin, azithromycin, doxycycline, or chloramphenicol for 4 days. On day 5, the media were replaced with fresh antibiotic-free medium and the cultures were maintained until day 28. On days 5, 13, and 28, immunofluorescence (IF) staining of O. tsutsugamushi was performed. IF staining on days 13 and 28 revealed increasing numbers of IF-positive foci in all cultures, even in cultures initially exposed to the highest concentration of rifampin (80 microg/mL), azithromycin (80 microg/mL), doxycycline (20 microg/mL), or chloramphenicol (100 microg/mL). The present study reveals that rifampin has no bactericidal effect against O. tsutsugamushi as observed for azithromycin, doxycycline, and chloramphenicol. A subpopulation of the bacteria that are not killed by high concentrations of the antibiotics may explain the persistence of O. tsutsugamushi in humans even after complete recovery from scrub typhus with antibiotic therapy.
Antibiotics, Antitubercular/*pharmacology ; Cell Line, Tumor ; Drug Resistance, Bacterial ; Fluorescent Antibody Technique ; Humans ; Orientia tsutsugamushi/*drug effects/growth & development/metabolism ; Rifampin/*pharmacology

The trend of antimicrobial resistance of bacteria isolated from patients in 30 Korean hospitals in 1999 was analyzed with a particular attention to cefotaxime- or fluoroquinolone-resistant gram-negative bacilli, imipenem-resistant Pseudomonas aeruginosa, and vancomycin-resistant enterococci. Adequacy of susceptibility testing, and any change in the frequencies of isolated species were also analyzed. The results showed that only 20% and 30% of hospitals tested the piperacillin-tazobactam and cefoxitin susceptibility of Enterobacteriaceae, respectively, only 24% of hospitals the piperacillin-tazobactam susceptibility of P. aeruginosa, and 17% of hospitals the fusidic acid susceptibility of staphylococci. Among the isolates 26.3% were glucose-nonfermenting gram-negative bacilli, and 34.7% of Enterococcus were Enterococcus faecium. Slight decline of cefotaxime-resistance rate to 20% was noted in Klebsiella pneumoniae, while fluoroquinolone-resistantce rate was 68% in Acinetobacter baumannii. The ceftazidime- and imipenem-resistance rates were 17% and 18%, respectively in P. aeruginosa. The vancomycin-resistance rate of E. faecium rose significantly to 15.1%, but the rates varied significantly depending on hospitals suggesting presence of different degree of selective pressure or nosocomial spread. In conclusion, the prevalence of imipenem-resistant P. aeruginosa and the increase of vancomycin-resistant E. faecium were the particularly worrisome phenomena observed in this study.
Anti-Infective Agents, Fluoroquinolone/*pharmacology ; Antibiotics/*pharmacology ; Cephalosporins/*pharmacology ; Drug Resistance, Microbial ; Enterobacteriaceae/drug effects ; Enterococcus/*drug effects ; Gram-Negative Bacteria/*drug effects ; Human ; Imipenem/*pharmacology ; Korea ; Microbial Sensitivity Tests ; Pseudomonas aeruginosa/drug effects ; *Vancomycin Resistance

EDTA-dependent pseudothrombocytopenia (PTCP) is the phenomenon of a spurious low platelet count due to EDTA-induced aggregation of platelets. Since the failure to recognize EDTA-dependent PTCP may result in incorrect diagnosis and inappropriate treatment, the recognition of this phenomenon is very important. We report an insidious case of EDTA-dependent PTCP confirmed by supplementation of kanamycin to anticoagulant in a 53-year-old women. Although sodium citrate and heparin usually prevented the aggregation of platelets in EDTA-dependent PTCP patients, these anticoagulants failed in preventing PTCP in our case. EDTA-dependent PTCP was confirmed by the findings that the clumping of platelets on microscopic evaluation was found in EDTA-anticoagulated blood samples, whereas thrombocytopenia and platelet aggregation were not revealed in the sample supplemented with kanamycin.
Antibiotics, Aminoglycoside/*pharmacology ; Anticoagulants/*adverse effects/pharmacology ; Case Report ; Edetic Acid/*adverse effects ; Female ; Human ; Kanamycin/*pharmacology ; Middle Age ; Platelet Aggregation/*drug effects ; Platelet Aggregation Inhibitors/*therapeutic use ; Platelet Count ; Thrombocytopenia/*blood/chemically induced

A minimal test scheme, consisting of deoxyribonuclease (DNase) and tween 80 hydrolysis (TEH) together with a few other biochemical tests, was used to make tentative identification of Serratia marcescens from clinical specimens. The identifications were reevaluated by testing comprehensive biochemical characteristics of 52 isolates, and all were found to be correct. The biochemical reactions of the isolates were very homogenous, showing typical characteristics of the species except in the urease test and acid production from sucrose, adonitol and inositol. These facts support the feasibility of the use of the minimal identification scheme. Pigment production was noted only in 7 isolates invalidating the value of this characteristic for the identification. Fifty-seven isolates were tested for their antibiotic susceptibility. They were found most frequently susceptible to gentamicin (47.4%), chloramphenicol (35.0%) and kanamycin (28.1%). Many isolates (49.1%) were multiply resistant to ampicillin, chloramphenicol, gentamicin, kanamycin, streptomycin and tetracycline.
Antibiotics/pharmacology* ; Cells, Cultured ; Drug Resistance, Microbial ; Human ; Microbial Sensitivity Tests ; Serratia marcescens/drug effects ; Serratia marcescens/isolation & purification ; Serratia marcescens/metabolism*

Yersinia pseudotuberculosis is known to cause septicemia, mesenteric lymphadenitis enteritis and erythema nodosum. Most of the infections were found in European countries, but none in Korea ti11 now. For the first time in Korea Y. pseudotuberculosis was isolated form a 51-year-old ma1e with liver cirrhosis. The patient showed chills, abdominal pain and diarrhea followed by a comatose state. The organism was isolated from both blood and peritoneal fluid. The isolation and identification were difficult as the organism grew slowly and many of the characteristics were similar to other enteric bacilli. The isolate was susceptible to all antibiotics tested in vitro, but our chemotherapy with ampicillin and kanamycin did not save the patient's life.
Antibiotics/pharmacology ; Human ; Male ; Middle Age ; Septicemia/microbiology* ; Yersinia/drug effects ; Yersinia/isolation & purification ; Yersinia Infections/microbiology* ; Yersinia pseudotuberculosis Infections/microbiology*