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Background: Emergence of extended spectrum ?-lactamase (ESBL) producing strains of Gram-negative bacteria can lead to serious infections frequently complicates the clinical and treatment outcome. Aims and Objectives: The purpose of this study was to know the prevalence of ESBLs and to know the most common Gram-negative bacteria, which produce ESBLs at our health-care facility. Materials and Methods: This study comprised all of the isolates of Gram-negative bacteria that were acquired from various clinical samples. For the purpose of the investigation, a sample of an isolate that showed resistance to two or more third-generation cephalosporins was taken. ESBL detection and antibiotic sensitivity tests were carried out using conventional microbiological techniques. Results: We isolated a total of 284 Gram-negative bacteria and 54 (19%) were identified as ESBL producers. Out 54 ESBL producers, 18 (33%) isolates were Escherichia coli, 11 (20%) were Pseudomonas aeruginosa, 12 (22%) were Klebsiellae, 6 (11%) were Enterobacter, 2 (4%) were Citrobacter, 4 (8%) were Acinetobacter, and 1 (2%) were Serratia spp. Conclusion: Clinical decision-makers can make the best antibiotic treatment by regularly monitoring multi-drug resistant bacteria like ESBL producers. This also helps to improve infection control procedures. In addition, we must maintain reserve medications like carbapenems on hand for judicial use.
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Objective: To computationally model the CTX-M-5 ?-lactamase and establish its structure, which is exclusively present in human-associated Salmonella. Methods: The CTX-M-5 aminoacid sequence (Uniprot ID:O65975) of Salmonella enterica subsp. enterica serovar typhimurium was retrieved from UniProt database and subjected to homology modeling using MODELLER 9v7. The homology models were duly validated using RAMPAGE tool by generating Ramachandran plots, ERRAT graphs, and ProSA score. DoGSiteScorer server and ConSurf server were used to detect the cavities, pockets, and clefts to identify conserved amino acid sites in the predicted model. Subsequently, the modeled structure was docked using CLC Drug Discovery Workbench against proven drugs and known inhibitors. Results: Obtained high-quality homology model with 91.7% of the residues in favorable regions in Ramachandran plot and qualified in other quality parameters. Docking studies resulted in a higher dock score for PNK (D-benzylpenicilloic acid) molecule when compared to other reported inhibitors. Conclusion: This in silico study suggests that the compound PNK could be an efficient ligand for CTX-M-5 ?-lactamase and serve as a potent inhibitor of CTX-M-5.
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Background & objectives: Infections caused by extended-spectrum ?-lactamase (ESBL)-producing Escherichia coli carrying blaCTX-M genes have been spreading globally, but there are geographical variations in the type of blaCTX-Mgenes prevalent and there are scanty data from India. This study was conducted to determine the CTX-M type ESBLs in E. coli isolates obtained from clinical specimens from patients with extra-intestinal infections attending a tertiary care hospital in south India. Methods: ESBL-producing E. coli isolated from patients with extra-intestinal infections were subjected to PCR using CTX-M group-specific primers. From a representative isolate, full-length CTX-M-15 gene was amplified and sequenced. An internal fragment of this gene was sequenced in 10 representative isolates. Results: Of the 300 isolates of E. coli tested, 88 per cent carried CTX-M genes and blaCTX-M-15was the most dominant gene present in 90 per cent of the positive isolates. Most (91%) of the isolates positive for blaCTX-M were sensitive to meropenem. Interpretation & conclusions: Our findings showed blaCTX-M-15 to be the dominant gene. Based on the data on antimicrobial susceptibility, cefoperazone-sulbactum could be an antimicrobial of choice.
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Objective To identify the genotypes of ESBLs-producing Klebsiella pneumoniae isolates from the First Affiliated Hospital,Shantou University Medical College.Methods The MICs of 10 antibiotics were determined by agar-dilution against the clinical isolates of ESBLs-producing K.pneumoniae.PCR were performed with specific primers for blaTEM,blaSHV, blaCTX-M and blaOXA respectively.PCR products were cloned and sequenced.Results The results of PCR showed that a- mong the 83 strains of ESBLs-producing K.pneumoniae,75 were positive for blaTEM,41 positive for blaSHV,25 poitive for blaCTX-M,9 positive for hlaOXA.Three genotypes were found in 13 strains(15.7%),2 genotypes in 59 strains (71.1%) and single genotype in only 11 strains(13.2%).The genes of CTX-M-3,TEM-1 and SHV were found co-existent in 9 strains. The strains carrying 2 or 3 ESBL genes were more resistant to antibiotics than those carrying only 1 ESBL gene.Conclusions The genotypes of ESBLs-producing Klebsiella pneumoniae in this hospital are blaTEM,blaSHV,blaCTX-M and blaOXA. Most strains carry 2 or 3 ESBL genes.
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OBJECTIVE To study antibiotic-resistant phenotypes and genotypes of ESBLs-producing Escherichia coli,Klebsiella pneumoniae and Klebsiella oxytoca isolated from children with pneumonia in Urumqi,to know the distribution and difference of these three Gram-negative bacilli from 2003 to 2007.METHODS Bacterial strains were identified by VITEK32,ESBLs were detected by confirmatory test recommended by CLSI.Microarray technique was used to determine the genotypes of ESBLs.RESULTS Antibiotic-resistant phenotypes showed ESBLs-producing K.oxytoca decreasing from 84.3% to 35.3%,K.pneumoniae stabling in 50-60%,E.coli increasing from 34.4% to 72.1% during the five years;genotypes indicated there were most of ctx-m-9 and tem+ctx-m-9 in E.coli,tem and shv in K.pneumoniae,and the most of tem+ctx-m-3 in K.oxytoca.CONCLUSIONS There is high percentage of ESBLs production from children in Urumqi;resistant phenotypes and genotypes of ESBLs are different in three Gram-negative bacilli;and must further enhance the regional epidemiology surveillance about ESBLs.
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BACKGROUND: The importance of extended-spectrum beta-lactamases (ESBL) produced in gramnegative bacilli is now well recognized, but most clinical laboratories have problems in detecting and interpreting ESBL and implicating the findings in nosocomial infections caused by ESBL producing gram-negative bacilli. The present study aims primarily to evaluate the distributions of these enzymes among Escherichia coli and Klebsiella pneumoniae, the most frequent isolates of Enterobacteriaceae producing ESBL, to differentiate the types of enzymes in theses isolates and finally to relate the clonality of specific types within a part of Daegu city. METHODS: The clinical isolates of 1, 242 E. coli and 859 K. pneumoniae were screened for ESBL production by the disk diffusion method of the National Committee of Clinical Laboratory Standard, and it was confirmed by the double-disk synergy test (DDS). Antimicrobial susceptibility test was performed by the agar dilution method. The presence of -lactamase was tested by polymerase chain reaction (PCR) and plasmid analysis. Isoelectric focusing and nucleotide sequence analysis were performed to evaluate ESBL types. Pulsed-field gel electrophoresis (PFGE) of XbaI-digested DNA fragments was carried out to determine the extend of clonality within the hospital. RESULTS: Of 34 isolates of E. coli and 31 isolates of K. pneumoniae ramdomly selected from those isolates screened for ESBL production were further tested by DDS to confirm its production: 30 (88.2%) E. coli and 29 (93.5%) K. pneumoniae were positive. TEM-52 and SHV-12 were present both in E. coli and K. pneumoniae, but SHV-2a was distributed only in K. pneumoniae. The resistance was transferable in 66.7% of E. coli and 68.9% of K. pneumoniae. Six and 5 PFGE patterns were shown by E. coli and K. pneumoniae, respectively. Among the 5 patterns of K. pneumoniae, type B was dominant, suggesting a clonal outbreak in the hospital. CONCLUSIONS: The ESBL specific enzyme types were TEM-52, SHV-2a and SHV-12. Despite many different PFGE patterns of the ESBL producing isolates, a few outbreak and edemic clones appear to be prevalent in Dongsan Medical Center.
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Agar , Base Sequence , beta-Lactamases , Clone Cells , Cross Infection , Diffusion , DNA , Electrophoresis, Gel, Pulsed-Field , Enterobacteriaceae , Escherichia coli , Isoelectric Focusing , Klebsiella pneumoniae , Plasmids , Pneumonia , Polymerase Chain ReactionABSTRACT
Objective:To investigate the drug resistance and genotypes of extended-spectrum ?-lactamase(ESBL)-producing Enterobacteriaceae bacteria in our hospital.Methods:257 strains of Enterobacteriaceae bacteria were isolated from clinical specimens in our hospital from Sept.2002 to Oct.2003.Sixty-three strains of ESBLs-producing isolates were detected by phenotypic confirmatory test according to NCCLS M100-S9.The susceptibility test of them to the antibiotics were detected with Bio-Merieux ATB G-5.The SHV-type,TEM-type,CTX-M-type encoding genes were amplified by PCR.Results:The resistant rates of the 63 strains to IMP,MERO,CXT,FEP,CAZ,AKN,CTX and CIP were 1.6%,1.6%,38.1%,39.7%,46.0%,55.6%,63.5% and 95.2%,repectively.The rates of Enterobacteriaceae bacteria carrying SHV-type,TEM-type,CTX-M-type ESBLs were 84.1%,47.6% and 25.4%,repectively.Conclusion:Multidrug resistance of the ESBLs-producing strains in our hospital is obvious.IMP and MERO are still the best choices for treatment of the infections caused by ESBLs-producing bacteria.Most of the ESBLs-producing strains carry SHV-type.CTX-M-type ?-lactamase exists prevalently in our hospital.
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BACKGROUND: Increase in extended-spectrum -lactamase(ESBL)-producing Escherichia coli and Klebsiella pneumoniae have been reported in Korea. The aim of this study was to determine the nationwide prevalence of ESBL-producing E. coli and K. pneumoniae, and to investigate the types of ESBLs. METHODS: A total of 2,221 E. coli and 1,128 K. pneumoniae consecutive isolates were yearly collected from 12 hospitals in 1999 and 2000. ESBL production was performed by National Committee for Clinical Laboratory Standards methods and double synergy tests. The type of ESBL was determined by polymerase chain reaction (PCR), isoelectric focusing, and nucleotide sequence analysis. RESULTS: ESBL-producing E. coli and K. pneumoniae isolates were detected from all 12 hospitals participated. The proportion of ESBL-producers was 9.1%(2.0-19.6%) of the E. coli and 29.2% (10.0-60.8%) of the K. pneumoniae isolates. Among the 22 isolates sequenced, SHV-12 was found in six isolates, SHV-2a in three isolates, TEM-52 in five isolates, TEM-106 in three isolates, and each of TEM-15, TEM-20, TEM-43, and TEM-107 in one isolate. CTX-M-14 was also found in one isolate. CONCLUSION: ESBL-producing E. coli and K. pneumoniae are widespred to all levels of Korean hospitals. The most common types of ESBLs in Korea are SHV-12, SHV-2a, and TEM-52. In addition, we also identified new TEM-derived ESBLs.
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Base Sequence , Escherichia coli , Escherichia , Isoelectric Focusing , Klebsiella pneumoniae , Klebsiella , Korea , Pneumonia , Polymerase Chain Reaction , PrevalenceABSTRACT
BACKGROUND: Because extended-spectrum -lactamase (ESBL) producing strains can frequent-ly cause therapeutic failure and infectious outbreaks in hospitals, rapid and accurate detection of these strains are important. We compared the Vitek ESBL test with the NCCLS ESBL phenotypic confirmatory test by disk diffusion (NCCLS ESBL test) and double disk synergy test (DDST). METHODS: For a total of 316 clinical isolates composed of Escherichia coli (184), Klebsiella pneu-moniae (120) and Klebsiella oxytoca (12), we performed the Vitek ESBL test and the NCCLS ESBL test. For sixty-eight ESBL producing isolates, the Vitek ESBL test was compared with the NCCLS ESBL test and the DDST. The ESBL producer was defined as an organism showing an increase in the inhibited zone diameter of >or=5 mm for either cefotaxime or ceftazidime in combination with clavu-lanic acid versus its single test. The DDST was performed with 20 mm and 30 mm for interdisk diam-eter. For seven false negative isolates in the Vitek ESBL test, the DDST of cefepime was performed. RESULTS: Compared with the NCCLS ESBL test, the Vitek ESBL test showed one false positive (specificity, 99.6%), seven false negatives (sensitivity, 89.7%) and 97.5% agreement. Seven false negative isolates of the Vitek ESBL test were the cefoxitin-resistant ESBL producer. In positivity for the NCCLS ESBL test of 68 ESBL producing isolates, cefotaxime-clavulanic acid and ceftazidime-clavulanic acid were 94% and 91%. Cefotaxime, ceftazidime, aztreonam and ceftriaxone showed 95/90%, 100/55%, 100/85% and 95/80% positivity in double-disk synergy with amoxicillin-clavulanic acid (AMC) for 20/30 mm of the interdisk diameter respectively. For seven false negative isolates of the Vitek ESBL test, cefepime showed a distinct synergic effect with AMC. CONCLUSIONS: The Vitek ESBL test may be a useful method for clinical laboratories due to its easy, rapid and sensitive method but its method was less sensitive to cefoxitin-resistant ESBL. For these cases, if the NCCLS ESBL test or DDST with cefepime are added, the detection rate of the ESBL pro-ducer can be augmented.
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Amoxicillin-Potassium Clavulanate Combination , Aztreonam , Cefotaxime , Ceftazidime , Ceftriaxone , Diffusion , Disease Outbreaks , Escherichia coli , Escherichia , Klebsiella oxytoca , KlebsiellaABSTRACT
BACKGROUND: The prevalence of extended-spectrum -lactamase (ESBL)-producing Klebsiella pneumoniae and Escherichia coli has been increased in Korea, but the testing and reporting ESBL-mediated resistance remains unclear. We undertook a study to evaluate the method to screen isolates of ESBL-producing K. pneumoniae and E. coli using cefpodoxime disk. METHODS: Fifty-eight strains of K. pneumoniae and 28 strains of E. coli were tested for production of ESBLs by the double disk synergy test. Susceptibility to cefpodoxime, ceftazidime, cefotaxime, and aztreonam was determined by disk diffusion method. RESULTS: All strains that produced ESBLs were resistant to cefpodoxime, whereas those that not produced ESBLs were susceptible (97%) to this agents. The disk diffusion test exhibited 100% sensitivity and 97% specificity when NCCLS conventional interpretive criteria were used. All other oxyimino- -lactam agents tested were inferior discriminators between the two groups of organisms. When NCCLS ESBL interpretive criteria were used, the disk diffusion test using cefpodoxime exhibited 100% sensitivity and 83% specificity. CONCLUSIONS: Routine disk diffusion susceptibility test with cefpodoxime disk (10g) can be used to detect strains of ESBL-producing K. pneumoniae and E. coli without include supplemental testing for ESBL production.
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Aztreonam , Cefotaxime , Ceftazidime , Diffusion , Escherichia coli , Escherichia , Klebsiella pneumoniae , Klebsiella , Korea , Pneumonia , Prevalence , Sensitivity and SpecificityABSTRACT
OBJECTIVE:To provide clinicians with reliable basis about rational use of antibacterials. METHODS:The gram-negative bacilli isolated clinically in our hospital from 2001 to 2008 and their drug resistance were analyzed retrospectively. RESULTS:A total of 14 428 strains of pathogenic bacteria were isolated from 2001 to 2008,of which,9 391 strains (65.1%) were gram-negative bacilli,leading the list were Escherichia coli,Pseudomonas aeruginosa,Enterobacter cloacae,Klebsiella pneumoniae and Acinetobacter,and the detected rate of Acinetobacter baumannii increased year by year. Gram-negative bacilli were resistant to commonly used antibacterials more or less,with their resistance rates to ampicillin on the high side,but their resistance rates to imipenem,pipercillin/tazobactam and amikacin were low. CONCLUSION:The composition of clinically isolated Gram-negative bacilli and their drug resistance patterns were always in a change,therefore,clinicians should familiarize with this change as well as the change of drug resistance and improve their level of rational use of antibiotics.