OBJECTIVETo investigate how acetamiprid, a new insecticide, affects the activity of superoxide dismutase (SOD), catalase (CAT), and ATPase and the SOD isozyme patterns in two G bacteria, E. coli K12 and Pse.FH2, and one G+ bacterum, B. subtilis.

METHODSThe SOD, CAT, and ATPase specific activities of cell lysates were determined spectrophotometrically at 550 nm, 240 nm, and 660 nm, respectively, with kits A001, A016, and A007. SOD isozyme patterns were detected by native PAGE analysis.

RESULTSSOD and CAT activities in the tested bacteria increased significantly in a concentration-dependent manner after different concentrations of acetamiprid were applied. The activity of SOD in B. subtilis and Pse.FH2 was stimulated and reached the highest level after treatment with 100 mg/L acetamiprid for 0.5 h. For Pse.FH2, there was another stimulation of SOD activity after acetamiprid application for about 8.0 h and the second stimulation was stronger than the first. The stimulation by acetamiprid showed a relative lag for E. coli K12. Acetamiprid seemed to exhibit a similar effect on CAT activity of the two G bacteria and had an evident influence on ATPase activity in the three bacteria within a relatively short period. Only one SOD isozyme was detectable in Pse.FH2 and B. subtilis, while different isozyme compositions in E. coli could be detected by native PAGE analysis.

CONCLUSIONAcetamiprid causes a certain oxidative stress on the three bacteria which may not only elevate SOD and CAT activities but also generate new SOD isozymes to antagonize oxidative stress. However, this oxidative stress lasts for a relatively short time and does not cause a long-term damage.

Adenosine Triphosphatases ; metabolism ; Bacillus ; drug effects ; enzymology ; Bacteria ; drug effects ; enzymology ; Catalase ; metabolism ; Escherichia coli ; drug effects ; enzymology ; Insecticides ; pharmacology ; Isoenzymes ; metabolism ; Neonicotinoids ; Pseudomonas ; drug effects ; enzymology ; Pyridines ; pharmacology ; Superoxide Dismutase ; metabolism

Coal Mining ; Humans ; Microbial Sensitivity Tests ; Pneumoconiosis ; microbiology ; Pseudomonas Infections ; microbiology ; Pseudomonas aeruginosa ; drug effects ; enzymology ; Respiratory Tract Infections ; microbiology ; Sputum ; microbiology ; beta-Lactam Resistance

BACKGROUND: We evaluated the combined use of the modified Hodge test (MHT) and carbapenemase inhibition test (CIT) using phenylboronic acid (PBA) and EDTA to detect carbapenemase-producing Enterobacteriaceae (CPE) and metallo-beta-lactamase (MBL)-producing Pseudomonas spp. METHODS: A total of 49 isolates of CPE (15 Klebsiella pneumoniae carbapenemase [KPC], 5 Guiana extended-spectrum beta-lactamase [GES]-5, 9 New Delhi metallo-beta-lactamase [NDM]-1, 5 Verona integron-encoded metallo-beta-lactamase [VIM]-2, 3 imipenem-hydrolyzing beta-lactamase [IMP], and 12 oxacillinase [OXA]-48-like), 25 isolates of MBL-producing Pseudomonas spp. (14 VIM-2 and 11 IMP), and 35 carbapenemase-negative controls were included. The MHT was performed for all isolates as recommended by the Clinical and Laboratory Standards Institute. Enhanced growth of the indicator strain was measured in mm with a ruler. The CIT was performed by directly dripping PBA and EDTA solutions onto carbapenem disks that were placed on Mueller-Hinton agar plates seeded with the test strain. RESULTS: Considering the results of the MHT with the ertapenem disk in Enterobacteriaceae and Pseudomonas spp., the CIT with the meropenem disk in Enterobacteriaceae, and the imipenem disk in Pseudomonas spp., three combined disk tests, namely MHT-positive plus PBA-positive, EDTA-positive, and MHT-positive plus PBA-negative plus EDTA-negative, had excellent sensitivity and specificity for the detection of KPC- (100% sensitivity and 100% specificity), MBL- (94% sensitivity and 100% specificity), and OXA-48-like-producing isolates (100% sensitivity and 100% specificity), respectively. CONCLUSIONS: Combined use of the MHT and CIT with PBA and EDTA, for the detection of CPE and MBL-producing Pseudomonas spp., is effective in detecting and characterizing carbapenemases in routine laboratories.
Bacterial Proteins/antagonists & inhibitors/*metabolism ; Boronic Acids/chemistry/pharmacology ; Disk Diffusion Antimicrobial Tests/*methods ; Edetic Acid/chemistry/pharmacology ; Enterobacteriaceae/drug effects/*enzymology ; Enterobacteriaceae Infections/diagnosis ; Humans ; Pseudomonas/drug effects/*enzymology ; Pseudomonas Infections/diagnosis ; Sensitivity and Specificity ; beta-Lactamases/chemistry/*metabolism

BACKGROUNDIn the present study, we characterized multidrug-resistant Pseudomonas aeruginosa (MDRP) clinical isolates from a paediatric facility and investigated the types and features of the metallo-beta-lactamases (MBLs) produced by carbapenem-resistant strains.

METHODSFour hundred and ninety-eight strains of Pseudomonas aeruginosa were isolated from patients at Beijing Children's Hospital between January 2005 and December 2006. The minimal inhibition concentrations (MICs) of the strains for 13 antibiotics were measured. A combination of the E test and PCR amplification/DNA sequencing was used to define the carbapenem-resistant strains.

RESULTSWe found that 24.1% (120/498) of the isolates were MDRP. The frequencies of resistance to imipenem and meropenem were 34.2% and 35.8%, respectively, and the MIC50 and MIC90 values for the two antibiotics were identical at 4 microg/ml and 32 microg/ml, respectively. The detection rate for carbapenem resistance was 49.2% (59/120). Among the 59 carbapenem-resistant Pseudomonas aeruginosa strains, 39 (66.1%) were positive for the MBL genotype; 35 (89.7%) strains carried the bla(IMP) gene and 4 (10.3%) strains carried the bla(VIM) gene. Neither bla(SPM) nor bla(GIM) was amplified from any of the 59 isolates. DNA sequencing revealed that IMP-1 was present in 35 IMP-producing isolates and VIM-2 was detected in four VIM-producing isolates.

CONCLUSIONSThese MDRP isolates exhibited high frequencies of resistance to carbapenems among clinical isolates from a paediatric facility in Beijing, China. The production of MBL appears to be an important mechanism for carbapenem resistance in Pseudomonas aeruginosa.

Carbapenems ; pharmacology ; Child ; Drug Resistance, Multiple, Bacterial ; Humans ; Microbial Sensitivity Tests ; Pseudomonas aeruginosa ; drug effects ; enzymology ; Sequence Analysis, DNA ; beta-Lactamases ; biosynthesis ; classification ; genetics

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

INTRODUCTIONAntibiotic resistance in gram-negative bacilli is an area of increasing importance. This prospective study was performed to survey antibiotic resistance in Escherichia coli (E. coli), Klebsiella spp., Pseudomonas aeruginosa and Acinetobacter spp. over a 1-year period.

MATERIALS AND METHODSNon-duplicate isolates of E. coli, Klebsiella spp., P. aeruginosa and Acinetobacter spp. were collected from participating Singapore hospitals during defined collection periods in 2006 and 2007. Confirmatory identification and antibiotic susceptibility testing were performed at Changi General Hospital. Minimum inhibitory concentrations (MIC) to a defined panel of antibiotics were determined using microbroth dilution methods. The presence of extended-spectrum beta lactamases and AmpC beta-lactamases in Enterobacteriaceae was determined by phenotypic methods, and susceptibility results were defined using current breakpoints from the Clinical Laboratory Standards Institute (CLSI).

RESULTSSeven hundred and forty-six gram-negative bacilli were received for testing. Resistance to extended-spectrum cephalosporins was present in a third of Enterobacteriaceae isolates, and extended-spectrum beta-lactamases (ESBL) carriage was present in 19.6% and 30.1% of E. coli and Klebsiella pneumoniae, respectively. AmpC enzymes were also detected in 8.5% and 5.6% of E. coli and K. pneumoniae isolates respectively. All Enterobacteriaceae were susceptible to imipenem and meropenem. The most active antibiotics against P. aeruginosa were amikacin, meropenem and piperacillin-tazobactam. A third of P. aeruginosa showed reduced susceptibility to polymyxin B. Carbapenem resistance was significantly higher in Acinetobacter baumannii (70.5%) than in other Acinetobacter species (25.0%). The most active antibiotic against A. baumannii was polymyxin B.

CONCLUSIONAntibiotic resistance is prevalent in gram-negative bacilli isolated from Singapore hospitals. The MIC testing surveillance programme complemented susceptibility data from wider laboratory-based surveillance, and has revealed emerging mechanisms of antibiotic resistance.

Acinetobacter Infections ; drug therapy ; Acinetobacter baumannii ; drug effects ; isolation & purification ; Anti-Bacterial Agents ; pharmacology ; therapeutic use ; Bacterial Proteins ; Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; enzymology ; Hospitals ; Humans ; Klebsiella Infections ; drug therapy ; Klebsiella pneumoniae ; drug effects ; enzymology ; Microbial Sensitivity Tests ; Prospective Studies ; Pseudomonas aeruginosa ; drug effects ; isolation & purification ; Singapore ; beta-Lactamases

No abstract available.
Anti-Bacterial Agents/pharmacology ; DNA, Bacterial/chemistry/genetics/metabolism ; Drug Resistance, Bacterial ; Integrons/*genetics ; Microbial Sensitivity Tests ; Pseudomonas aeruginosa/drug effects/*enzymology/isolation & purification ; Sequence Analysis, DNA ; beta-Lactamases/*genetics

OBJECTIVE: To determine the relation between resistance of hypermutable Pseudomonas aeruginosa and beta-lactamases produced. METHODS: The bacteria cultured were identified with API 20NE system. Susceptibilities of the bacteria were detected by disk diffusion method. The hypermutable strains were tested with broth dilution assays. The beta-lactamases produced by these strains were characterized by 3-dimensional test and 2-mercaptopropanoic acid inhibited assays. RESULTS: Altogether 120 strains were analyzed and 45 (37.5%) trains were hypermutable.The resistant rates of hypermutable strains were close to or above 60.0% for imipenem, meropenem, cefoperazone/sulbactam, piperacillin/ tazobactam, ceftazidime, cephfime, aztreonam, amikacin and ciprofloxacin.The 3-dimensional test showed that 18 (40.0%) strains produced extended spectrum beta-lactamases (ESBLs), 25 (55.6%) strains produced AmpC enzymes, and 6 (13.3%) strains produced metallo-beta-lactamases. CONCLUSION The resistant rates of hypermutablce strains of Pseudomonas aeruginosa to routine antibiotics are high, which is one of the most important reasons for multi-drug resistance that the hypermutable strains produced ESBLs, AmpC enzymes, and metallo-beta-lactamases.
Adult ; Aged ; Aged, 80 and over ; Bronchitis, Chronic ; microbiology ; Drug Resistance, Multiple, Bacterial ; genetics ; Female ; Humans ; Male ; Middle Aged ; Mutation ; Pseudomonas aeruginosa ; drug effects ; enzymology ; genetics ; Pulmonary Heart Disease ; microbiology ; beta-Lactamases ; biosynthesis