Humans ; Microbial Sensitivity Tests ; Pneumoconiosis ; microbiology ; Sputum ; microbiology ; beta-Lactam Resistance ; beta-Lactamases ; analysis

BACKGROUND: Of the plasmid-mediated AmpC beta-lactamases (ABLs), CMY-2 is the most prevalent and is distributed in many countries. However, little is known about the emergence and characteristics of CMY-2 among Escherichia coli isolates in Korea. The aims of this study were to detect the emergence of the CMY-2 beta-lactamase in clinical isolates of E. coli from various regions in Korea. METHODS: Eighteen cefoxitin non-susceptible isolates of 1, 130 consecutive, nonrepeat isolates of E. coli at five university hospitals were tested for antimicrobial susceptibility by the broth microdilution method. The cefoxitin non-susceptible isolates were further investigated by AmpC disk tests, double disk synergy (DDS) tests, isoelectric focusing, CMY-2-specific PCR, DNA sequencing, and plasmid analysis. RESULTS: Seven (0.6%) isolates of plasmid-mediated ABL-producing E. coli were found at three of the five hospitals; all seven isolates produced CMY-2 beta-lactamase and one of the isolates was also tested positive by the DDS test. All isolates demonstrated different plasmid patterns by plasmid analysis. CONCLUSIONS: Our data indicate that CMY-2-producing E. coli has emerged and is prevalent in the medical institution in Korea. Therefore, constant surveillance is needed to prevent its further spread.
beta-Lactamases ; Cefoxitin ; Escherichia coli* ; Hospitals, University ; Isoelectric Focusing ; Korea ; Plasmids ; Polymerase Chain Reaction ; Sequence Analysis, DNA

BACKGROUND/AIMS: Bacteremia following endoscopic retrograde cholangiopancreatography (ERCP) is a severe complication, but the risk factors for this condition have not yet been clearly determined. Thus, the aim of this study was to investigate the risk factors of post-ERCP bacteremia. METHODS: Among patients who underwent ERCP from June 2006 to May 2009, we selected patients without any signs of infection prior to the ERCP procedures. Of these patients, we further selected those who experienced bacteremia after ERCP as well as two-fold age and sex-matched controls who did not experience bacteremia after ERCP procedures. We compared clinical, laboratory and technical aspects between these two groups. RESULTS: There were 70 patients (3.1%) who developed bacteremia after ERCP. In the multivariate analysis, a history of previous liver transplantation, an elevated serum alkaline phosphatase level and an endoscopic retrograde biliary drainage procedure were independent risk factors of post-ERCP bacteremia (p=0.006, p=0.001, and p=0.004, respectively). The microbiologic analysis revealed the presence of gram-negative organisms in 80% of the cases, and 11 patients had infections with bacteria expressing extended spectrum beta-lactamases. Pseudomonas infection was significantly more common in patients who received liver transplantation as compared to patients without transplantation (p=0.014). CONCLUSIONS: A history of liver transplantation, elevated serum alkaline phosphatase levels and endoscopic retrograde biliary drainage procedure were independent risk factors of post-ERCP bacteremia and require additional attention in future studies.
Alkaline Phosphatase ; Bacteremia ; Bacteria ; beta-Lactamases ; Cholangiopancreatography, Endoscopic Retrograde ; Drainage ; Humans ; Liver Transplantation ; Multivariate Analysis ; Pseudomonas Infections ; Risk Factors ; Transplants

OBJECTIVETo investigate the possible differences in antimicrobial resistance of Escherichia coli isolated from different samples in children.

METHODSSix hundred and twenty-nine samples from urine, sputum, blood and secretion were collected from June 2004 to May 2009 for bacterial identification by VITEK-32 automatic system and antimicrobial susceptibility tests by Kirby-Bauer method. The drug resistance rate of Escherichia coli isolated from different samples was compared.

RESULTSTwo hundred and sixty strains of Escherichia coli were isolated , and 108 of which were from urine , 64 from sputum, 54 from secretion and 23 from blood. ESBLs were detected in 96 (36.9%) of the 260 isolates, AmpC enzymes in 32 (12.3%), and ESBLs+AmpC in 8 (3.1%). The ESBLs positive rate of Escherichia coli isolates from sputum was significantly higher than that from other samples (P<0.05). The antimicrobial resistance rate of Escherichia coli strains from different samples to amoxicillin/clavulanic acid, ticarcillin/clavulanic acid, piperacillin, cefotaxime, cefuroxime, cefepime, gentamicin, cotrimoxazole, and nitrofurantoin was different. The resistance rate of the strains from sputum samples was higher than that from the other samples (P<0.05).

CONCLUSIONSEscherichia coli isolated from different samples have different antimicrobial resistance rates in children, so the selection of antibiotics for infections confirmed by bacterial cultures from different samples should based on drug sensitivity results.

Adolescent ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; enzymology ; isolation & purification ; Female ; Humans ; Male ; beta-Lactamases ; analysis

Extended-spectrum beta-lactamases (ESBLs) in gram-negative organisms have been implicated as the enzymes responsible for resistance to oxyimino-cephalosporins. The incidence of ESBL- producers in Korean isolates of Escherichia coli and Klebsiella pneumoniae were in the range of 4.8 7.5% and 22.5 22.8%, respectively. The ESBL-producing isolates revealed variable levels of resistance to cefotaxime, ceftazidime and aztreonam. They also showed the elevated MIC values of non-beta-lactam antibiotics. SHV-12 and SHV-2a were the enzymes most frequently found in K. pneumoniae strains, but TEM-52 was the most prevalent in E. coli isolates. About 15% of ESBL-producing isolates of Enterobacteriaceae produced CMY-1 enzyme, which conferred resistance to cephamycins such as cefoxitin as well as oxyimino-cephalosporins. Thus, the most common types of ESBLs in Korea are TEM-52, SHV-12, SHV-2a, and CMY-1.
Drug Resistance, Microbial/physiology ; Enterobacteriaceae/isolation & purification ; Enterobacteriaceae/chemistry* ; Enterobacteriaceae Infections/microbiology ; Human ; Korea ; beta-Lactamases/analysis*

BACKGROUND: Extended-spectrum beta-lactamase (ESBL)-producing Salmonella have been increasingly reported worldwide. ESBL-producing Salmonella is of particular concern since children cannot be treated with quinolones. This study was conducted to determine the phenotypic and genetic characteristics of ESBL-producing Salmonella in a tertiary hospital. MATERIALS AND METHODS: Four clinical ESBL-producing isolates of non-typhoidal Salmonella were collected during 2001 to 2009. Antimicrobial susceptibility was determined by disk diffusion test and VITEK-II system. ESBL production was tested by ESBL phenotypic confirmatory test. TEM, SHV, CTX-M1, CTX-M2, CTX-M8, and CTX-M9 type ESBL genes were detected by PCR amplification, and PCR products were subjected to direct sequencing. RESULTS: Phenotypic confirmatory test showed that 4 of the 300 non-typhoidal Salmonella isolates were ESBL-producing: 3 S. Enteritidis and 1 S. Typhimurium. All 4 isolates were recovered during the past 1 year period. All 3 S. Enteritidis harbored CTX-M-15, while the S. Typhimurium harbored CTX-M-14. All CTX-M-15-producing S. Enteritidis isolates showed resistance both to cefotaxime and ceftazidime, while the CTX-M-14-producing S. Enteritidis were resistant only to cefotaxime. CONCLUSIONS: ESBL-producing nontyphoidal Salmonella has emerged recently and the type of ESBL has switched from TEM and SHV to CTX-M.
beta-Lactamases ; Cefotaxime ; Ceftazidime ; Child ; Diffusion ; Humans ; Legionella pneumophila ; Oligonucleotide Array Sequence Analysis ; Polymerase Chain Reaction ; Quinolones ; Salmonella

The gene and the amino acid sequence of the structural and regulatory region of the Pseudomonas aeruginosa with different resistance patterns were analyzed. Six strains with different resistance patterns were selected and the AmpC beta-lactamase was identified. The objective gene fragment was amplified by colonies PCR. The sequences of the PCR-products were analyzed. The DNA sequence of the structural gene ampC and the regulatory genes ampR, ampD and ampE was detected. The 6 strains and the wild-type Pseudomonas aeruginosa are highly homogeneous in structural and regulatory region. Some new mutant points were found.
Bacterial Proteins/*genetics ; DNA, Bacterial/genetics ; Point Mutation/*genetics ; Pseudomonas aeruginosa/enzymology ; Pseudomonas aeruginosa/*genetics ; Sequence Analysis, DNA ; beta-Lactam Resistance/*genetics ; beta-Lactamases/*genetics

OBJECTIVETo study the genotype distribution of extended-spectrum p-lactamases (ESBLs) and AmpC p-lactamases produced in E. coli isolated from men with urinary infection in Nanjing.

METHODSOrganisms of clinical infection were identified by automatic microbial system (Vitek-32). ESBLs were detected by disk diffusion confirmatory test, and ESBLs and AmpC p-lactamases by three-dimensional extract test (TDET) , the presence of plasmid-mediated ESBLs and ampC genes determined by PCR, and conjugal transfer assays of the ampC resistance determinants carried out by a broth mating procedure.

RESULTSESBLs were produced in 24. 6% (46/187) of the E. coli and the 46 E. coli isolates showed p-lactamase activity in TDET, 3 positive for both ESBLs and AmpC beta-lactamases and 43 for ESBLs only. Forty-four of the 46 isolates were shown by PCR to contain at least one of the genes blaTEM, blaOXA, bla(CTX-M), but no blaSHA. AmpC specific amplication products were observed in 3 of the 46 isolates, of which 2 were of CIT type, and 1 of DHA type. All of the 3 transconjugants transferred the plasmids harbouring ampC genes to recipients.

CONCLUSIONCTX-M is the most common genotype in plasmid-mediated ESBLs produced by E. coli isolated from men with urinary infection in Nanjing. Present findings indicate that AmpC-producing E. coli are present in this hospital, and ampC-encoding plasmids are transferable.

Bacterial Proteins ; analysis ; genetics ; Drug Resistance, Bacterial ; Escherichia coli ; classification ; enzymology ; genetics ; Genotype ; Humans ; Male ; Plasmids ; genetics ; Polymerase Chain Reaction ; Urinary Tract Infections ; microbiology ; beta-Lactamases ; analysis ; genetics

OBJECTIVES: The prevalence of carbapenem-resistant Enterobacterales (CRE) presents a significant challenge in clinical anti-infective treatment. This study aims to investigate drug resistance and the molecular epidemiological characteristics of CRE in our area. Additionally, we seek to evaluate practicality of utilizing carbapenemase inhibitor enhancement test in clinical laboratory. METHODS: Non-repeated CREs isolated from clinical specimens at Xiangya Hospital, Central South University, were collected. Minimum inhibitory concentration (MIC) combined with Kirby-Bauer (KB) assay was used to detect the drug susceptibility of the strains, and 13 carbapenemase-producing genes were detected by PCR. The phenotype of 126 strains of carbapenemase-producing Enterobacterales identified by PCR was detected by the carbapenemase inhibitor enhancement test to understand the agreement between the method and the gold standard PCR results. RESULTS: Among 704 CRE strains examined, we observed significant drug resistance in 501 strains dentified as carbapenemase-producing Enterobacterales (CPE). Klebsiella pneumoniae was the predominant CPE strain, followed by Enterobacter cloacae and Escherichia coli. A total of 9 carbapenemase types were detected, including Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-β-lactamase (NDM), Verona integron- encoded metallo-β-lactamases (VIM), imipenemase (IMP), oxacillinase-48 (OXA-48), and rare imipenem-hydrolyzing β-lactamase (IMI), adelaide imipenemase (AIM), Bicêtre carbapenemase (BIC), and guiana extended-spectrum β-lactamase (GES). The detection rate of KPC serine carbapenemase was 61.7% (309/501). The carbapenemase inhibitor enhancement test exhibited a 100% consistency rate for the strains producing Class A serine carbapenemase and/or Class B metallo-β-lactamases. CONCLUSIONS CRE strains in Changsha, Hunan, China, are wide distribution and exhibit carbapenemase production. The main mechanism of carbapenem resistance in these bacterias is predominatly attributed to the production of KPC serine carbapenemase. The presence of GES and IMI genes carried by Enterobacterales has been detected for the first time in this region. The carbapenemase inhibitor enhancement test has been proven to be an accurate method for detecting CRE producing Class A serine carbapenemase and/or Class B metallo-β-lactamases. This method offers simpicity of operation and ease of results interpretation, making it weel-suited meeting the clinical microbiology laboratory's reguirements for the detection of serine carbapenemase and metallo-β-lactamases.
Humans ; Carbapenems/pharmacology* ; Molecular Epidemiology ; Bacterial Proteins/analysis* ; beta-Lactamases/analysis* ; Klebsiella pneumoniae/genetics* ; Escherichia coli ; Microbial Sensitivity Tests ; Serine ; Anti-Bacterial Agents/pharmacology*

BACKGROUND: Outbreaks of carbapenem resistant P. aeruginosa give rise to significant therapeutic challenges for treating nosocomial infections. In this study, we analyzed carbapenem resistance mechanisms in carbapenem resistant and clonally different P. aeruginosa strains. We analyzed chromosomal alterations in the genes of OprD and efflux system regulatory proteins (MexR, NalC, NalD, MexT, and MexZ). We also investigated chromosomal alterations in the quinolone resistance-determining region (QRDR) for quinolone resistance mechanisms. METHODS: Twenty-one clonally different P. aeruginosa strains were isolated by repetitive extragenic palindromic sequence-based PCR (rep-PCR). PCR and DNA sequencing were conducted for the detection of beta-lactamase genes and chromosomal alterations of efflux pump regulatory genes, oprD, and QRDR in gyrA, gyrB, parC, and parE. RESULTS: Only one (P28) of the 21 strains harbored bla VIM-2. Two isolates had mutations in nalD or mexZ that were associated with efflux pump overexpression. Chromosomal alterations causing loss of OprD were found in 4 out of 21 carbapenem resistant P. aeruginosa strains. Nine of 10 imipenem and ciprofloxacin resistant strains had alterations in gyrA and/or parC. CONCLUSION: Carbapenem resistance in P. aeruginosa was mediated by several mechanisms, including loss of the OprD, overexpression of efflux systems, and production of carbapenemase. Resistance to quinolone is frequently caused by point mutations in gyrA and/or parC.
Bacterial Proteins ; beta-Lactamases ; Ciprofloxacin ; Cross Infection ; Disease Outbreaks ; Genes, Regulator ; Imipenem ; Point Mutation ; Polymerase Chain Reaction ; Proteins ; Pseudomonas ; Pseudomonas aeruginosa ; Sequence Analysis, DNA