OBJECTIVEIn order to use facultative gut bacteria as an alternate to animals for the initial gastrointestinal toxicity screening of heavy metals, a comparative study on rat intestinal epithelial cells and resident gut bacteria was undertaken.

METHODSin vitro growth rate of four gut bacteria, dehydrogenase (DHA) and esterase (EA) activity test, intestinal epithelial and bacterial cell membrane enzymes and in situ effect of arsenite were analysed.

RESULTSGrowth profile of mixed resident population of gut bacteria and pure isolates of Escherichia coli, Pseudomonas sp., Lactobacillus sp., and Staphylococcus sp. revealed an arsenite (2-20 ppm) concentration-dependent inhibition. The viability pattern of epithelial cells also showed similar changes. DHA and EA tests revealed significant inhibition (40%-72%) with arsenite exposure of 5 and 10 ppm in isolated gut bacteria and epithelial cells. Decrease in membrane alkaline phosphatase and Ca2+ -Mg2+ -ATPase activities was in the range of 33%-55% in four bacteria at the arsenite exposure of 10 ppm, whereas it was 60%-65% in intestinal epithelial villus cells. in situ incubation of arsenite using intestinal loops also showed more or less similar changes in membrane enzymes of resident gut bacterial population and epithelial cells.

CONCLUSIONThe results indicate that facultative gut bacteria can be used as suitable in vitro model for the preliminary screening of arsenical gastrointestinal cytotoxic effects.

Animals ; Arsenites ; pharmacology ; Cell Membrane ; drug effects ; Culture Media ; Epithelial Cells ; drug effects ; enzymology ; microbiology ; Esterases ; metabolism ; Gram-Negative Bacteria ; drug effects ; enzymology ; growth & development ; Gram-Positive Bacteria ; drug effects ; enzymology ; growth & development ; Humans ; Intestines ; cytology ; drug effects ; microbiology ; Oxidoreductases ; metabolism ; Rats ; Teratogens ; pharmacology

INTRODUCTIONImipenem and meropenem are treatment of choice for extended-spectrum betalactamase (ESBL)-positive gram-negative bacteraemia. They may select for carbapenemresistant Acinetobacter baumannii and Pseudomonas aeruginosa; ertapenem may not do so as it is inactive against these bacteria. Clinical efficacy of ertapenem in ESBL-producing gramnegative bacteraemia is limited.

MATERIALS AND METHODSRetrospective study of patients with ESBL-positive gram-negative bacteraemia treated with ertapenem was undertaken.

RESULTSForty-seven patients with multidrug-resistant gram-negative bacteraemia (79% produced ESBL) were treated with ertapenem for a median duration of 11 days. The median age was 70 years. Septic shock occurred in 19% and mechanical ventilation was needed in 17%. Klebsiella pneumoniae comprised 53% and Escherichia coli 26%. Urinary infection accounted for 61% and hepatobiliary 15%. Favourable clinical response occurred in 96%. Attributable mortality was 4%.

CONCLUSIONErtapenem is promising in culture-guided step-down therapy of ESBL-positive gram-negative bacteraemia.

Adult ; Aged ; Aged, 80 and over ; Anti-Bacterial Agents ; pharmacology ; therapeutic use ; Bacteremia ; drug therapy ; etiology ; Drug Resistance, Multiple, Bacterial ; Escherichia coli ; drug effects ; enzymology ; Escherichia coli Infections ; drug therapy ; microbiology ; Female ; Gram-Negative Bacteria ; drug effects ; enzymology ; Gram-Negative Bacterial Infections ; drug therapy ; microbiology ; Humans ; Klebsiella Infections ; drug therapy ; microbiology ; Klebsiella pneumoniae ; drug effects ; enzymology ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Retrospective Studies ; Urinary Tract Infections ; complications ; drug therapy ; beta-Lactamases ; biosynthesis ; beta-Lactams ; pharmacology ; therapeutic use

OBJECTIVE: To investigate the relationship between emergence of AmpC enzyme and drug resistance in the gram-negative bacilli in Xiangya Hospital and to provide information for the treatment of antibiotics. METHODS: The bacteria were identified; the susceptibility was determined by Microscan microbiological identification system; and the AmpC enzyme was detected by disc diffusion method. RESULTS: Of the 204 gram-negative strains, the positive rate of AmpC enzyme was 19.61%; AmpC-positive strains resisted to ceftriaxone, piperacillin, ceftazidime, cefotaxime, cefoperazone, aztreonam, piperacillin/tazobactam, cefuroxime, ceftazidime/clavulanic, and cefotaxime/clavulanic. But AmpC-negative strains were susceptible to those antibiotics. There were significant differences, between the two groups (All P < 0.05). Both groups were susceptible to cefepime, imipenem, meropenem, cefoperazone/sulbactam, levofloxacin, and amikacin. CONCLUSION The detection of AmpC enzyme is helpful to the screen of drug resistant strains. Most bacilli with AmpC enzyme show the resistance to third-generation cephosporins, aztreonam, and the beta-lactamase inhibitors, but susceptible to imipenem, cefepime, meropenem, cefoperazone/sulbactam, levofloxacin, and amikacin, which provides the information for the antibiotic therapy.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Bacterial Proteins ; analysis ; Child ; Child, Preschool ; Drug Resistance, Microbial ; Drug Resistance, Multiple, Bacterial ; Female ; Gram-Negative Bacteria ; drug effects ; enzymology ; Humans ; Infant ; Male ; Microbial Sensitivity Tests ; Middle Aged ; beta-Lactamases ; analysis

Metallo-beta-lactamase (MBL) production usually results in high-level resistance to most beta-lactams, and a rapid spread of MBL producing major gram-negative pathogens is a matter of particular concern worldwide. However, clinical data are scarce and most studies compared MBL producer (MP) with MBL non-producer (MNP) strains which included carbapenem susceptible isolates. Therefore, we collected clinical data of patients in whom imipenem-nonsusceptible Pseudomonas aeruginosa (PA) and Acinetobacter baumannii (AB) were isolated from sputum or urine, and investigated MBL production and the risk factors related with MBL acquisition. The antimicrobial susceptibility patterns were also compared between MPs and imipenem-nonsusceptible MNPs (INMNP). Among the 176 imipenem-nonsusceptible isolates, 12 MPs (6.8%) were identified. There was no identifiable risk factor that contributed to the acquisition of MPs when compared to INMNPs, and case-fatalities were not different between the two groups. The percentage of susceptible isolates was higher among MPs for piperacilin/tazobactam and fluoroquinolones while that of ceftazidime was higher in INMNPs (p < 0.05). As regards to aztreonam, which has been known to be a uniquely stable beta-lactam against MBLs, susceptibility was preserved in only two isolates (16.7%) among MPs, and was not higher than that of INMNPs (23.2%). In conclusion, the contribution of MBLs to imipenem non-susceptibility in PA/ABs isolated from sputum and urine was relatively limited, and there was no significant risk factor associated with acquisition of MPs compared with INMNPs. However, limited susceptibility to aztreonam implies that MPs may hold additional resistance mechanisms, such as extended spectrum beta-lactamases, AmpC beta-lactamases, or other non-enzymatic mechanisms.
Adult ; Aged ; Aged, 80 and over ; Anti-Bacterial Agents/pharmacology/therapeutic use ; Child ; Child, Preschool ; Electrophoresis, Gel, Pulsed-Field ; Female ; Gram-Negative Bacteria/drug effects/*enzymology/isolation & purification ; Gram-Negative Bacterial Infections/drug therapy/enzymology/microbiology ; Humans ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Republic of Korea ; Sputum/*microbiology ; Urine/*microbiology ; beta-Lactam Resistance ; beta-Lactamases/*metabolism

The trends and types of carbapenemase-producing Gram-negative bacilli were analyzed from clinical specimens collected between 2005 and 2012 at a Korean teaching hospital. The proportions of carbapenem-resistant Acinetobacter spp. increased markedly to 66%. Metallo-beta-lactamase producers significantly decreased and the majority shifted from the bla(VIM-2) type to the bla(IMP-1) type.
Acinetobacter/classification/drug effects/*enzymology ; Acinetobacter Infections/drug therapy ; Anti-Bacterial Agents/*pharmacology ; Bacterial Proteins ; Carbapenems/*pharmacology ; Drug Resistance, Microbial ; Gram-Negative Bacteria/*drug effects/enzymology/isolation & purification ; Humans ; Incidence ; Microbial Sensitivity Tests/trends ; Population Surveillance ; Pseudomonas/classification/drug effects/enzymology ; Republic of Korea/epidemiology ; beta-Lactamases/biosynthesis/*drug effects

BACKGROUND: Rapid detection of carbapenemase-producing gram-negative bacilli (GNB) is required for optimal treatment of infected patients. We developed and assessed a new disk carbapenemase test (DCT). METHODS: Paper disks containing 0.3 mg of imipenem and bromothymol blue indicator were developed, and the performance of the DCT were evaluated by using 742 strains of GNB with or without carbapenemases. RESULTS: The paper disks were simple to prepare, and the dried disks were stable at -20℃ and at 4℃. The DCT detected 212 of 215 strains (98.6% sensitivity with 95% confidence interval [CI] 96.0-99.5%) of GNB with known class A (KPC and Sme) and class B (NDM, IMP, VIM, and SIM) carbapenemases within 60 min, but failed to detect GES-5 carbapenemase. The DCT also detected all two Escherichia coli isolates with OXA-48, but failed to detect GNB with OXA-232, and other OXA carbapenemases. The DCT showed 100% specificity (95% CI, 99.2-100%) in the test of 448 imipenem-nonsusceptible, but carbapenemase genes not tested, clinical isolates of GNB. CONCLUSIONS: The DCT is simple and can be easily performed, even in small laboratories, for the rapid detection of GNB with KPC, NDM and the majority of IMP, VIM, and SIM carbapenemases.
Anti-Bacterial Agents/*pharmacology ; Bacterial Proteins/*metabolism ; Bromthymol Blue/chemistry ; Drug Resistance, Bacterial ; Gram-Negative Bacteria/drug effects/*enzymology ; Imipenem/pharmacology ; Microbial Sensitivity Tests/*methods ; Paper ; beta-Lactamases/*metabolism

BACKGROUND: Since metallo-beta-lactamase (MBL)-producing isolates can hydrolyze carbapenem and also easily transfer the resistance genes to other bacteria, a rapid and accurate detection of MBL has become very important. We evaluated the utility of Mueller Hinton agar (MHA) biplate containing dipicolinic acid (DPA) as a screening method to detect IMP-1 and VIM-2 type MBL-producing isolates. METHODS: Based on our preliminary tests using various concentrations of DPA, 200 and 300 microg/mL concentration of DPA were chosen for further study. Bacterial lawns were grown on MHA biplate, one half of which contained DPA while the other did not. The inhibition zone around the imipenem (IPM) disk on both sides of this plate was compared. The stability of DPA in the stored DPA-MHA biplate was also evaluated during three months using two MBL- and one non-MBL-producing isolates. RESULTS: When the criterion of a > or =7 mm increase of inhibition zone around the IPM disk on the MHA containing DPA compared to MHA without DPA was used, the sensitivities and specificities were 94.7% and 97.6% for 200 microg/mL DPA-MHA biplate, and 98.2% and 97.6% for 300 microg/mL DPA-MHA biplate, respectively. The activity of the DPA in this biplate was stable for three months. CONCLUSIONS: Assays using DPA 300-MHA biplate were highly sensitive and specific for the detection of IMP-1 and VIM-2 type MBL-producing bacteria. In addition, it is easy to perform; so, it may be useful to apply this method for detection of IMP-1 and VIM-2 type MBL in clinical laboratories.
Agar ; Anti-Bacterial Agents/*pharmacology ; Bacteriological Techniques ; Chelating Agents/chemistry/*pharmacology ; Drug Resistance, Bacterial ; Gram-Negative Bacteria/drug effects/enzymology/*isolation & purification ; Imipenem/*pharmacology ; Picolinic Acids/chemistry/*pharmacology ; Reagent Kits, Diagnostic ; Sensitivity and Specificity ; beta-Lactamases/*analysis/biosynthesis

OBJECTIVETo analyze the characteristic of bacterial infections, and the relationship between antibiotics treatment and bacterial infections after liver transplantation, and to prevent antibiotic-resistant bacterial infections.

METHODS86 liver transplant recipients were retrospected. Different indexes including limited daily dose, the frequency of medication, drug use index were used to evaluate the rationality of the use of antibiotics, three-dimensional test was used to explore extended-spectrum beta-lactamase and AmpC enzyme of Gram-negative bacteria.

RESULTSThe major pathogens of infection after liver transplantation were Enterococcus faecalis, Enterobacter cloacae, fungi and E. coli. Pre-operative antibiotic utilization rate was 83.7%, it was mainly a single use of antibiotics; After- operative antibiotic usage was 100.0%, it was mainly joint use of two or three antibiotics; The top 3 antibiotics used were cephalosporins, the combined enzyme inhibitors and penicillin. Antibiotics with drug utilization index (DUI) more than 1.1 included ampicillin and Lalin proxy. 43.3% and 31.8% of Gram -Negative bacteria produced ESBLs and AmpC, respectively, while 21.3% Gram -Negative bacteria produced two enzymes.

CONCLUSIONThere is high incidence of bacterial infections after liver transplantation. The use of antibiotics is high dose, high-frequency and reasonable; High resistance of bacterial infections was prone to develop and the prevention of the high resistance of bacterial infections is very important.

Adolescent ; Adult ; Aged ; Anti-Bacterial Agents ; administration & dosage ; therapeutic use ; Bacterial Infections ; drug therapy ; etiology ; microbiology ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Gram-Negative Bacteria ; drug effects ; enzymology ; isolation & purification ; Gram-Positive Bacteria ; drug effects ; enzymology ; isolation & purification ; Humans ; Infant ; Liver Transplantation ; adverse effects ; methods ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Postoperative Complications ; drug therapy ; epidemiology ; microbiology ; Retrospective Studies ; Young Adult ; beta-Lactamases ; biosynthesis