OBJECTIVETo study the risk factors for infection with extended-spectrum beta-lactamase (ESBL) producing strains in children.

METHODSThe clinical data of 242 pediatric in-patients with lower respiratory tract infections from February 2009 to January 2011 were retrospectively analyzed. The risk factors of ESBL-producing strain infections were investigated using univariate analysis and multivariate logistic regression analysis.

RESULTSUnivariate analysis showed that six factors were related with ESBL-producing strain infections: repeated sucking of phlegm (OR: 2.279, P<0.01), tracheal intubation(OR: 3.101, P<0.01), administration of the third generation cephalosporin for more than three days (OR: 3.628, P<0.01), admission to the pediatric intensive care unit (PICU) (OR: 2.378, P<0.01), indwelling of nasogastric tube (OR: 2.460, P<0.01), prophylactic use of antibiotics (OR: 1.747, P<0.05). Multivariate logistic regression showed that the application of the third-generation cephalosporin for more than three days (OR: 5.672, P<0.01), repeated sucking of phlegm (OR: 3.917, P<0.01), tracheal intubation (OR: 3.717, P<0.01), indwelling of nasogastric tube (OR: 2.961, P<0.01), and admission to PICU (OR: 3.237, P<0.01) were the independent risk factors for the infections.

CONCLUSIONSThe infections of ESBL-producing strains are caused by many factors, among which the application of the third-generation cephalosporin for more than three days, invasive operations, and admission to PICU are the independent risk factors.

Adolescent ; Bacterial Infections ; etiology ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Male ; Risk Factors ; beta-Lactamases ; biosynthesis

Bacterial Infections ; drug therapy ; Child ; Drug Resistance, Bacterial ; Humans ; Microbial Sensitivity Tests ; beta-Lactamases ; biosynthesis

OBJECTIVETo investigate the epidemiological status of extended-spectrum beta-lactamase (ESBL) producing Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) and the drug resistance profiles of such organisms.

METHODSA total of 282 clinical isolates of E. coli and 180 of K. pneumoniae were collected from different districts of Zhejiang Province. Inhibitor potentiated broth dilution tests were performed for detecting extended-spectrum beta-lactamases. Etests were performed to detect the drug resistance of these strains against nine commonly used antibiotics.

RESULTSThe prevalence of extended-spectrum beta-lactamases in E. coli and K. pneumoniae was 34.0% and 38.3%, respectively. The average prevalence of extended-spectrum beta-lactamases in E. coli and K. pneumoniae was 35.7%. The resistance prevalence of extended spectrum beta-lactamase producing strains to ceftazidime and cefotaxime was 40% and 26% respectively, so were those to cefepime, cefoxitin, piperacillin-tazobactam, cefoperazone-sulbactam, amikacin and ciprofloxacin. All these strains were sensitive to imipenem.

CONCLUSIONThe results in this study showed that the prevalence of extended-spectrum beta-lactamases was high, while extended-spectrum beta-lactamase producing strains were resistant to most antimicrobial agents except imipenem.

Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; enzymology ; Humans ; Klebsiella pneumoniae ; drug effects ; enzymology ; Microbial Sensitivity Tests ; beta-Lactamases ; biosynthesis

OBJECTIVETo identify risk factors for Klebsiella pneumoniae carbapenemase-producing Klebsiella pneumoniae (KPC-Kp) colonization in neonates hospitalized in the neonatal intensive care unit (NICU).

METHODSA case-control study was conducted. The case group included nine patients colonized with KPC-Kp between 1 August 2012 and 31 April 2013 and the controls were selected randomly from patients without KPC-Kp colonization during the same period. Univariable analysis and multivariable logistic regression analysis were conducted to identify risk factors for KPC-Kp colonization.

RESULTSThe univariable analysis showed 11 factors associated with KPC-Kp colonization: gestational age, birth weight, length of hospital stay, duration of mechanical ventilation, congenital heart disease, peripherally inserted central catheter, surgical operation, duration of intravenous nutrition, carbapenems use, duration of carbapenems use and glycopeptides use. The multivariable logistic regression analysis showed that exposure to more than 4 days of carbapenems use (OR=18.7, 95%CI: 1.98-175.5, P=0.01) was an independent risk factor for KPC-Kp colonization. The intervention to control KPC-Kp colonization included contact isolation, active surveillance, and rational use of antibiotics.

CONCLUSIONSExposure to prolonged use of carbapenems is an independent risk factor for the development of KPC-Kp colonization in neonates hospitalized in the NICU.

Bacterial Proteins ; biosynthesis ; Carbapenems ; adverse effects ; Female ; Humans ; Infant, Newborn ; Intensive Care Units, Neonatal ; Klebsiella pneumoniae ; enzymology ; isolation & purification ; Logistic Models ; Male ; Risk Factors ; beta-Lactamases ; biosynthesis

To produce TEM-116 extended-spectrum beta-lactamase (ESBL) from recombinant bacteria in a cost-effective way, we purified and renatured the recombinant TEM-116 ESBL from the inclusion bodies by Ni(2+)-NTA affinity and gel filtration chromatography through subcloning the bla(TEM-116) into expression vector pET28a(+), transforming into Escherichia coli BL21(DE3) and inducing with IPTG. We characterized the purified protein that had the molecular weight of 30 kDa and specific activity of 476 IU/mg. The recombinant TEM-116 ESBL showed higher efficiency in eliminating penicillin and cephalosporin in vitro and in vivo. Specifically, the recombinant TEM-116 ESBL could eliminate 7000 mg penicillin G (PG) when used at 10.0 IU in 1 L fermentation medium. When used at 320.0 IU, it could also degrade a mix of PG, ampicillin and cefazolin each at 200 mg in 1 L of urine. In milk, 1.0-2.5 IU of the recombinant enzyme could remove 80 U/L of PG. The recombinant enzyme was fully active at the temperature ranged from 4 degrees C to 37 degrees C. Furthermore, the recombinant enzyme used at 2.0x10(4)-2.3x10(4) IU/(kg bw) (body weight) eliminated 8.0x10(4)-9.1x10(4) microg/(kg bw) PG in mouse models in vivo. The recombinant TEM-116 ESBL has the potential as a tool enzyme in food and environmental protection to eliminate harmful residues of antibiotics.
Animals ; Cephalosporins ; antagonists & inhibitors ; Escherichia coli ; genetics ; metabolism ; Genetic Vectors ; genetics ; Mice ; Penicillins ; antagonists & inhibitors ; Recombinant Proteins ; biosynthesis ; genetics ; isolation & purification ; pharmacology ; beta-Lactamases ; biosynthesis ; genetics ; isolation & purification

OBJECTIVETo investigate the distribution and drug resistance spectrum of clinical bacterial and Candida isolates.

METHODSMost of the bacterial isolates were identified using automated BD Phoenix, and a few with K-B method carried out manually. Candida isolates were identified by color-display plate and K-B method.

RESULTSThe most common isolates in the 2478 strains were P. aeruginosa (15.6%), E. coli (11.5%), C. albicans (9.6%), K. pneumoniae (9.3%), S. aureu (8.2%), and S. epidermidis (7.5%). In gram-negative isolates, the antibiotics with the lowest resistance rate were meraopenem (14.4%), cefoperazone/Sulbactam (14.8%), Imipenem (21.9%), piperacillin/tazobactam (27.4%), ceftazidime (30.0%), amikacin (31.1%), and cefepime (33.1%). The detection rate of E.coli and K. pneumoniae isolates producing extended spectrum beta-lactamase (ESBLs) were 47.4% and 37.3% respectively. In gram-positive isolates, the antibiotics with the lowest resistance rate were vancomycin (0.9%), teicoplanin (1.1%), nitrofurantoin (6.9%), amikacin (20.1%), chloramphenicol (30.7%), and cefoperazone/sulbactam (31.5%). The methecillin-resistant rates of S. aureu , S. epidermidis, and S. haemolyticus were 57.1%, 65.0%, and 66.0%. For Candida isolates, the most sensitive antibiotics were amphotericin B (0.3%), nystain (0.3%), itraconazole (5.6%), fluconazole (9.4%), and fluorocytosine (9.4%).

CONCLUSIONThe results suggest high rate of ESBL production and oxacillin resistance of the bacteria isolated in the hospital. More rational use of antimicrobial agents is crucial for reducing the drug-resistance of the bacteria, and effective measures must be taken to reduce dissemination of multidrug-resistant bacteria.

Anti-Infective Agents ; pharmacology ; Bacteria ; drug effects ; isolation & purification ; Candida ; drug effects ; isolation & purification ; Drug Resistance, Bacterial ; Drug Resistance, Fungal ; Microbial Sensitivity Tests ; Oxacillin ; pharmacology ; beta-Lactamases ; biosynthesis

OBJECTIVETo investigate the characteristics of New Delhi metallo-beta-lactamase-1 (NDM-1) gene of Klebsiella pneumoniae (K. pneumoniae) emerging in Hunan, and its relationship to antibiotic resistance.

METHODSThe clinical strain was isolated from a sputum sample of a child with severe pnemonia and toxic myocarditis who was admitted into a general hospital of Hunan Province. VITEK-2 compact instrument was used for bacterial identification and antibiotic susceptibility test. Modified Hodge test was used for the screening of carbapenemase. EDTA-synergy test and combination disk diffusion test were used for detection of metallo-&beta;-lactamase (MBL). PCR was performed for amplification of NDM-1 genes and the positive products were sequenced and analyzed with BLAST. Conjugation was also performed to analyze mechanisms of antibiotic resistance. The results of antibiotic susceptibility tests were compared before and after conjugation.

RESULTSThe isolated strain was identified as K.pneumoniae. Modified Hodge test, EDTA-synergy test and combination disk diffusion test were all positive for the strain. The homology between gene sequence of PCR amplification products and NDM-1 gene FN396876.1 in the GenBank was 100%. Transconjugant DNA was used as template for the amplification of NDM-1 gene. The amplification products were sequenced and found to be the same as the NDM-1 gene amplification product of the donor strain. The MIC of transconjugant E.coli J53 (NDM-1) to all the &beta;-lactams increased significantly compared with the recipient strain E.coli J53. The MIC of ertapenem and imipenem increased by more than 8 times, while the MIC of ceftazidime and ceftriaxone increased by more than 64 times.

CONCLUSIONSThis study first identified a strain of K. pneumoniae carrying NDM-1 in mainland China. NDM-1 gene can be transmitted among different strains and causes extensively drug-resistance to &beta;-lactams.

Base Sequence ; China ; Drug Resistance, Bacterial ; Klebsiella pneumoniae ; drug effects ; enzymology ; genetics ; Molecular Sequence Data ; Polymerase Chain Reaction ; beta-Lactamases ; biosynthesis ; genetics

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

BACKGROUND: This study was performed to investigate the prevalence of qnr genes in clinical isolates of Escherichia coli from Korea that produce extended-spectrum beta-lactamases (ESBLs). METHODS: During the period of May to June 2005, we collected clinical isolates of E. coli that were intermediate or resistant to ceftazidime and/or cefotaxime from 11 Korean hospitals. Antimicrobial susceptibility was determined by the disk diffusion and agar dilution methods. ESBL production was confirmed phenotypically by the double-disk synergy test. ESBL and qnr genes were searched for by PCR amplification, and the PCR products were then subjected to direct sequencing. RESULTS: Double-disk synergy tests were positive in 84.3% (118/140) of ceftazidime- and/or cefotaxime-nonsusceptible E. coli isolates. The most prevalent types of ESBL in E. coli isolates were CTX-M-14 (N=41) and CTX-M-15 (N=58). Other ESBLs were also identified, including CTX-M-3 (N=7), CTX-M-9 (N=8), CTX-M-12 (N=1), CTX-M-57 (N=1), SHV-2a (N=2), SHV-12 (N=17) and TEM-52 (N=4). The qnrA1 and qnrB4 genes were identified in 4 and 7 ESBL-producing isolates, respectively. CONCLUSIONS: CTX-M-type enzymes were the most common type of ESBL in E. coli isolates from Korea, and the qnr genes were not uncommon in ESBL-producing E. coli isolates. Dissemination of E. coli containing both ESBL and qnr genes could compromise the future usefulness of the expanded-spectrum antibiotics for the treatment of infections.
Disk Diffusion Antimicrobial Tests ; Escherichia coli/*enzymology/genetics/isolation & purification ; Escherichia coli Proteins/classification/*genetics ; Humans ; Inhibitory Concentration 50 ; Polymerase Chain Reaction ; beta-Lactamases/biosynthesis/genetics/*metabolism

In this study, we investigated the molecular characteristics of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae isolates that were recovered from an outbreak in a Korean hospital. A new multilocus sequence typing (MLST) scheme for K. pneumoniae based on five housekeeping genes was developed and was evaluated for 43 ESBL-producing isolates from an outbreak as well as 38 surveillance isolates from Korea and also a reference strain. Overall, a total of 37 sequence types (STs) and six clonal complexes (CCs) were identified among the 82 K. pneumoniae isolates. The result of MLST analysis was concordant with that of pulsedfield gel electrophoresis. Most of the outbreak isolates belonged to a certain clone (ST2), and they produced SHV-1 and CTX-M14 enzymes, which was a different feature from that of the K. pneumoniae isolates from other Korean hospitals (ST20 and SHV-12). We also found a different distribution of CCs between ESBL-producing and -nonproducing K. pneumoniae isolates. The MLST method we developed in this study could provide unambiguous and well-resolved data for the epidemiologic study of K. pneumoniae. The outbreak isolates showed different molecular characteristics from the other K. pneumoniae isolates from other Korean hospitals.
Electrophoresis, Gel, Pulsed-Field ; Hospitals ; Humans ; Klebsiella pneumoniae/*classification/enzymology/genetics/isolation & purification ; Sequence Analysis, DNA ; beta-Lactamases/*biosynthesis ; Mycobacteria, Atypical/*drug effects/genetics/isolation & purification