BACKGROUND: We compared the performance of the modified Hodge test (MHT), Triton Hodge test (THT), Carba NP test (CNPt), simplified Carba NP test (CNPt-direct), blue-Carba NP test (BCT), and carbapenem inactivation method (CIM) for rapid and accurate carbapenemase detection. METHODS: The methods were evaluated by using 256 gram-negative isolates, including 197 Enterobacteriaceae (79 Enterobacter spp., 74 Klebsiella spp., 33 Escherichia coli, 10 Citrobacter spp., and 1 Serratia marcescens), 51 Acinetobacter baumannii, and 8 Pseudomonas aeruginosa strains. The collection included 117 non-carbapenemase, 18 Klebsiella pneumoniae carbapenemases (KPC) producers, 46 New Delhi metallo-β-lactamases (NDM) producers, 11 imipenemases (IMP) producers, and 51 oxacillinases (OXA) producers, and 13 strains harboring two different carbapenemase genes. RESULTS: The specificity of the THT (91.5%) was significantly lower than other methods, each of which had 100% specificity (P<0.003). This can be attributed to the false detection of Ampler class C β-lactamases (AmpC) carriers. The CNPt-direct and CIM yielded the highest sensitivities (P<0.003), which were comparable (92.8% vs 93.5%, P>0.999). Because of improved detection of NDM carriers, THT showed significantly higher sensitivity than the MHT (84.9% vs 75.5%, P<0.001). However, poor performances in detecting OXA still influenced the sensitivities of the CNPt (66.2%) and BCT (82.0%), as well as the MHT and THT. CONCLUSIONS: CNPt-direct and CIM demonstrated the best performance for the efficient detection of carbapenemase among the six evaluated methods. Except the MHT and THT, the detection of carbapenemase-producing Enterobacteriaceae by all the other methods was acceptable, when the OXA-type carbapenemase was not prevalent.
Acinetobacter baumannii ; Citrobacter ; Enterobacter ; Enterobacteriaceae ; Escherichia coli ; Gram-Negative Bacteria* ; Klebsiella ; Klebsiella pneumoniae ; Methods* ; Neptune ; Pseudomonas aeruginosa ; Sensitivity and Specificity ; Serratia

BACKGROUND: The increasing incidence of multidrug-resistant gram-negative bacteria causing nosocomial infections is an important clinical problem. Isepamicin is a recently developed aminoglycoside which has been known to have potent activity against gram-negative organisms. We evaluated the in vitro activities of isepamicin and other aminoglycosides against a large number of gram-negative organisms. MATERIALS AND METHODS: We tested the in vitro antimicrobial activities of isepamicin, amikacin, gentamicin, and tobramycin against 566 gram-negative organisms collected between January 2006 and June 2006 in Asan Medical Center. Minimal inhibitory concentrations (MICs) were determined and interpreted according to the recommendations of Clinical and Laboratory Standard Institute (CLSI). The breakpoint MIC used for interpretation of isepamicin was MIC< or =16 microgram/mL as susceptible, 32 microgram/mL as intermediate, and > or =64 microgram/mL as resistant. RESULTS: The MIC50/MIC90 of isepamicin for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterobacter cloacae were 1/2, 0.5/>128, 4/16, 16/>128, and 1/2 microgram/mL, respectively. The susceptibilities for E. coli, K. pneumoniae, P. aeruginosa, A. baumannii, and E. cloacae were 100%, 86.4%, 89.7%, 50.0%, and 96.6%, respectively. For E. coli, K. pneumoniae, P. aeruginosa, and E. cloacae, isepamicin had better in vitro activities than gentamicin and tobromycin, and had similar activities with amikacin. For A. baumanii, all four tested aminoglycosides had similar in vitro activities. CONCLUSION: Isepamicin had excellent in vitro activities against gram-negative organisms, except A. baumanii. The overall in vitro activities were similar with amikacin.
Acinetobacter baumannii ; Amikacin ; Aminoglycosides* ; Chungcheongnam-do ; Cloaca ; Cross Infection ; Enterobacter cloacae ; Escherichia coli ; Gentamicins ; Gram-Negative Bacteria ; Incidence ; Klebsiella pneumoniae ; Pneumonia ; Pseudomonas aeruginosa ; Tobramycin

BACKGROUND: The increasing incidence of multidrug-resistant gram-negative bacteria causing nosocomial infections is an important clinical problem. Isepamicin is a recently developed aminoglycoside which has been known to have potent activity against gram-negative organisms. We evaluated the in vitro activities of isepamicin and other aminoglycosides against a large number of gram-negative organisms. MATERIALS AND METHODS: We tested the in vitro antimicrobial activities of isepamicin, amikacin, gentamicin, and tobramycin against 566 gram-negative organisms collected between January 2006 and June 2006 in Asan Medical Center. Minimal inhibitory concentrations (MICs) were determined and interpreted according to the recommendations of Clinical and Laboratory Standard Institute (CLSI). The breakpoint MIC used for interpretation of isepamicin was MIC< or =16 microgram/mL as susceptible, 32 microgram/mL as intermediate, and > or =64 microgram/mL as resistant. RESULTS: The MIC50/MIC90 of isepamicin for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterobacter cloacae were 1/2, 0.5/>128, 4/16, 16/>128, and 1/2 microgram/mL, respectively. The susceptibilities for E. coli, K. pneumoniae, P. aeruginosa, A. baumannii, and E. cloacae were 100%, 86.4%, 89.7%, 50.0%, and 96.6%, respectively. For E. coli, K. pneumoniae, P. aeruginosa, and E. cloacae, isepamicin had better in vitro activities than gentamicin and tobromycin, and had similar activities with amikacin. For A. baumanii, all four tested aminoglycosides had similar in vitro activities. CONCLUSION: Isepamicin had excellent in vitro activities against gram-negative organisms, except A. baumanii. The overall in vitro activities were similar with amikacin.
Acinetobacter baumannii ; Amikacin ; Aminoglycosides* ; Chungcheongnam-do ; Cloaca ; Cross Infection ; Enterobacter cloacae ; Escherichia coli ; Gentamicins ; Gram-Negative Bacteria ; Incidence ; Klebsiella pneumoniae ; Pneumonia ; Pseudomonas aeruginosa ; Tobramycin

PURPOSE: Bacteremia in immunocompromised pediatric cancer patients can lead to high morbidity and mortality, if not treated early and properly. The incidence and antibiotic sensitivities to common pathogens of bacteremia in pediatric cancer patients are liable to change, according to region and time. We investigated the causative organisms and antibiotic sensitivities of bacteremia in pediatric cancer patients to assess the adequacy of empiric antimicrobial therapy. METHODS: From September 1995 to August 2003, we retrospectively evaluated 58 episodes in 39 pediatric cancer patients with bacteremia treated at the Pediatric Department of Yeungnam University Hospital. We investigated and analyzed the causative organisms and the antibiotic sensitivity test results by reviewing the records of the microbiologically proven positive blood culture results. RESULTS: The incidence of bacteremia in pediatric cancer patients in this study was 5.7 percent (58 episodes out of 1, 022 occasions of blood cultures). Gram-positive organisms were isolated more often than gram-negative organisms (63.8 percent vs 36.2 percent) in the following order: Staphylococcus epidermidis (37.9 percent), Staphylococcus aureus (17.3 percent), Escherichia coli (12 percent), Streptococcus (8.6 percent), Enterobacter (6.9 percent), Klesiella (6.9 percent), Serratia (3.5 percent), Acinetobacter (3.5 percent), Proteus (1.7 percent) and Morganella morganii (1.7 percent). In antibiotic sensitivity tests, only six of 37 isolates (16 percent) of gram positive bacteria were sensitive to penicillin and 15 of 37 isolates (40 percent) were sensitive to oxacillin. All except one Staphylococcus aureus were sensitive to vancomycin and all except one Staphylococcus epidermidis were sensitive to teicoplanin among 37 isolates of gram positive bacteria. In the case of gram negative bacteria, two of 21 isolates (10 percent) and four of 21 isolates (19 percent) were sensitive to cefotaxime and ceftazidime, respectively. Only six of 21 isolates (29 percent) were sensitive to aminoglycoside, but all 21 isolates (100 percent) were sensitive to imipenem. All seven isolates tested after the year 2000 were sensitive to meropenem. CONCLUSION: In conclusion, we should choose the proper antimicrobials in treating pediatric cancer patients with suspected bacteremia, reflecting the increasing episodes of gram positive bacteremia and polymicrobial resistance of gram positive and negative organisms.
Acinetobacter ; Bacteremia* ; Cefotaxime ; Ceftazidime ; Enterobacter ; Escherichia coli ; Gram-Negative Bacteria ; Gram-Positive Bacteria ; Humans ; Imipenem ; Incidence ; Morganella morganii ; Mortality ; Oxacillin ; Penicillins ; Proteus ; Retrospective Studies ; Serratia ; Staphylococcus aureus ; Staphylococcus epidermidis ; Streptococcus ; Teicoplanin ; Vancomycin

Multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa are highly dangerous nosocomial pathogens, cause the symptoms of skin infections, pressure sores, sepsis, blood stream and wound infections. Unfortunately, these pathogens are immune to the most common antibiotics, such as, carbapenem, aminoglycoside and fluoroquinolone. Therefore, it is imperative that new and effective antibiotics be developed. In the present study, the antimicrobial effects of Aloe vera MAP (modified Aloe polysaccharide) on Staphylococcus aureus and Bacillus subtilis, Escherichia coli and Enterobacter aerogenes, and clinical Pseudomonas aeruginosa and clinical Acinetobacter baumannii were comprehensibly investigated. Prior to the growth inhibition effect measurement and antibiotic disc diffusion assay on gram-positive and gram-negative bacteria and selected multidrug-resistant Pseudomonas aeruginosa and Acinetobacter baumannii, antimicrobial resistance screening was performed for the multidrug-resistant bacteria obtained from clinical isolates. The results for showed the Aloe vera MAP had a concentration-dependent effect on all of examined bacteria, particularly on Pseudomonas aeruginosa. Anti-inflammatory and anti-oxidant experiments were also performed dose dependently effects to confirm the beneficial physiological effects of Aloe vera MAP.
Acinetobacter baumannii ; Aloe* ; Anti-Bacterial Agents ; Bacillus subtilis ; Bacteria* ; Diffusion ; Enterobacter aerogenes ; Escherichia coli ; Gram-Negative Bacteria ; Mass Screening ; Pressure Ulcer ; Pseudomonas aeruginosa ; Rivers ; Sepsis ; Skin ; Staphylococcus aureus ; Wound Infection

The increasing prevalence of antimicrobial-resistant bacteria has become a serious problem in many parts of the world, including Korea. The resistance of of Gram-positive cocci was once considered to be a more serious problem, but the recent emergence of multi-resistant Gram-negative bacilli has raised great concerns. In Korea, the prevalence of ESBL-producing Escherichia coli and Klebsiella pneumoniae and fluoroquinolone-resistant E. coli, K. pneumoniae, Acinetobacter spp., and Pseudomonas aeruginosa has gradually increased. The increase in imipenem resistance was slight in P. aeruginosa, but drastic in Acinetobacter spp. It is certain that problematic antimicrobial-organism combinations are prevalent in Korea, increase of resistant bacteria will continue in the future. The development of new antimicrobial agents is considered difficult. Therefore, it is very important to use existing antimicrobial agents prudently, to extend the efficacy, to prevent infections, and tostrengthen infection control measures to prevent spread of resistant bacteria.
Acinetobacter ; Anti-Infective Agents ; Bacteria ; Escherichia coli ; Gram-Negative Bacteria ; Gram-Positive Cocci ; Imipenem ; Infection Control ; Klebsiella pneumoniae ; Korea ; Pneumonia ; Prevalence ; Pseudomonas aeruginosa

Aims: Tryptamine is an amine compound derived from tryptophan by decarboxylation process. This compound can be found in fermented food and beverages, and in human gut and skin as well. This study aims to investigate the effect of tryptamine, on Gram-negative bacteria, namely Escherichia coli, Serratia marcescens and Pseudomonas aeruginosa. Methodology and results: In this study, we used E. coli, S. marcescens and P. aeruginosa due to their relatively observable quorum sensing-regulated phenotype, such as motility, prodigiosin and pyocyanin sequentially. Our results showed that tryptamine started to inhibit the growth and prodigiosin production of S. marcescens at concentration 250 μg/mL, while it inhibits the growth and pyocyanin production of P. aeruginosa at concentration 250 μg/mL and 500 μg/mL, respectively. Tryptamine inhibits both the growth and motility of E. coli at concentration 100 μg/mL. Conclusion, significance and impact of study These results suggest that tryptamine is able to inhibit the growth of E. coli, S. marcescens and P. aeruginosa at relatively high concentration, thus decreases the quorum sensing-regulated phenotypes. It implies that the growth and quorum sensing of Gram-negative bacteria most likely will not be affected by the low concentration of tryptamine that present in the gut.
Tryptamines ; Gram-Negative Bacteria ; Serratia marcescens ; Pseudomonas aeruginosa ; Escherichia coli

To use in the identification of Legionella pneumophila isolates, one Legionella genus-specific, an two L. pneumophila species-specific monoclonal antibodies (MAbs) were produced. Reactivities of the MAbs with Legionella species and non-Legionella strains were tested by immunoblot. MAb 7D8-F1, MAb 7D8-A9, and MAb 1G12-C11 reacted only with protein. MAb 7D8-F1 recognized a genus-specific epitope in the protein ranged from 28 to 34 kDa in the tested 40 species with 61 serogroups. MAb 7D8-A9 and MAb 1G12-C11 reacted strongly with 49 kDa and 70 kDa protein from 18 L. pneumophila serogroups but did not react with 39 non-L. pneumophila species, respectively. In addtion, 17 non-Legionella strains, including Coxiella burnetii, Klebsiella pneumoniae, Mycoplasma pneumoniae, Pseudomonas areoginosa, Francisella tularensis, and Staphylococcus pneumoniae did not show cross-reacivities with the three MAbs. The MAbs reacted with 28 environmemtal isolates and three clinical isolates previously identified as L. pneumophila. When the immunoblot patterns were divided into four types (type I~IV) by using MAb 7D8-F1, all the 31 isolates belonged to the type II. These results indicate that the MAbs were highly specific to Legionella and can be used for the identification of L. pneumophila isolates on the genus and species levels.
Antibodies, Monoclonal* ; Coxiella burnetii ; Francisella tularensis ; Klebsiella pneumoniae ; Legionella pneumophila ; Legionella* ; Mycoplasma pneumoniae ; Pneumonia ; Pneumonia, Mycoplasma ; Pseudomonas ; Staphylococcus

Animal models are essential to studies of infectious diseases. The use of mice to test bacterial infection has been extensively reported. However, methods applied to clinical isolates, particularly for carbapenem-resistant bacteria, must be tailored according to the infection models and bacteria used. In this study, we infected 6-week-old female BALB/c mice intraperitoneally with different strains of resistant bacteria plus 3% hog gastric mucin. This method was found to be efficient and readily applicable for investigation of carbapenem-resisant Gram-negative pathogens (e.g., Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii) detected in Korea.
Acinetobacter ; Animals ; Bacteria ; Bacterial Infections ; Communicable Diseases ; Escherichia coli ; Female ; Gastric Mucins* ; Gram-Negative Bacteria* ; Humans ; Klebsiella pneumoniae ; Korea ; Methods ; Mice ; Models, Animal ; Peritonitis* ; Pseudomonas aeruginosa

The continuous emergence of new antimicrobial resistance in major human pathogens is a serious threat to clinical medicine, that increases mortality, morbidity, length of hospitalization, and the cost of healthcare. This review article focuses on the current status of antimicrobial resistance and future strategies to overcome antimicrobial resistance. In the community, multidrugresistant Streptococcus pneumoniae, community-associated methicillin-resistant Staphylococcus aureus (MRSA), and extended-spectrum beta-lactamaseproducing Enterobacteriaceae are major issues. In the hospital, an increasing prevalence of multidrug-resistant or pan-drug resistant gram-negative bacteria such as Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii are emerging problems, while MRSA still remains the major cause of nosocomial infections. Strategies to control antimicrobial resistance include effective antimicrobial treatment, vaccination, infection control and appropriate policies and regulations. Continuous surveillance activities both in Korea and in an international setting are essential. Control of antimicrobial resistance should be a national priority based on a multisectoral approach, and international collaboration.
Acinetobacter baumannii ; Clinical Medicine ; Cooperative Behavior ; Cross Infection ; Delivery of Health Care ; Drug Resistance, Multiple ; Enterobacteriaceae ; Escherichia coli ; Gram-Negative Bacteria ; Hospitalization ; Humans ; Infection Control ; Klebsiella pneumoniae ; Korea ; Methicillin-Resistant Staphylococcus aureus ; Prevalence ; Pseudomonas aeruginosa ; Social Control, Formal ; Streptococcus pneumoniae ; Vaccination