β-Lactamases involved in resistance to broad-spectrum cephalosporins in Escherichia coli and Klebsiella spp. clinical isolates collected between 1994 and 1996, in Barcelona (Spain) (original) (raw)
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Antimicrobial Agents and Chemotherapy, 2000
To estimate the diversity of extended-spectrum β-lactamases in Brazil, 18 strains from different species of the familyEnterobacteriaceae exhibiting a positive double-disk synergy test were collected by a clinical laboratory from several hospitals in Rio de Janeiro, Brazil, in 1996 and 1997. Four strains (Proteus mirabilis, Enterobacter cloacae,Enterobacter aerogenes, and Citrobacter amalonaticus) hybridized with a 550-bp CTX-M probe. The P. mirabilis strain produced a CTX-M-2 enzyme. The E. cloacae, E. aerogenes, and C. amalonaticus isolates harbored a bla gene which was identified by cloning and sequencing as abla CTX-M gene. E. coli HB101 transconjugants and the E. coli DH5α transformant harboring a recombinant plasmid produced a CTX-M β-lactamase with an isoelectric point of 7.6 conferring a resistance phenotype characterized by a higher level of resistance to cefotaxime than to ceftazidime, as observed with the other CTX-M enzymes. The deduced protein sequence showed a novel Amb...
Escherichia coli isolates that produce Extended-Spectrum â-Lactamase (ESBL) and AmpC â-lactamases not only cause treatment failure, but usually carry resistance genes for other antibiotics, which limits the choice of therapy. This study focused on the prevalence, detection and comparison of ESBL-type resistance genes (TEM, SHV, and CTX-M) with plasmid-mediated AmpC-producing genes (MOX, CIT, DHA) from E. coli isolates from Northwest of Iran. A total of 146 ceftazidime-resistance Escherichia coli clinical isolates were collected from hospitalized cases of urinary tract infection from Northwest of Iran. Phenotypic and genotypic examination by PCR was done for the presence of ESBL and AmpC genes by PCR. One hundred and twenty eight (87.8%) and 18 (12.3%) isolates were detected possibly as ESBLs and AmpC producers respectively. Of these, 135(92.5%) of the isolates harbored bla CTXM, 105(71.9%) bla TEM , 111(76%) bla SHV, 47(32.2%) CIT, 8(5.5%) MOX and 2 (1.4%) DHA gene. Findings of the present study indicates high rate of resistance to beta-lactam antibiotics due to CTX-M, TEM and SHV genes. Secondly, in 32% of AmpC isolates CIT genes was detected, which indicates high prevalence of this gene. This findings shows importance of developing local stewardship program for antibiotic consumption and screening isolates for the presence of ESBL and AmpC genes.
Drug Resistance due to Elaboration of Beta Lactamases and the Role of CTX-M in Enterobacteriaceae
Journal of Bahria University Medical and Dental College
The Enterobacteriaceae family are the most common pathogens associated with hospital and community acquired infections worldwide. These bacteria are treated with broad spectrum antibiotics especially 3rd generation cephalosporins. Over the period of time due widespread and rigorous use of these medications, Enterobacteriaceae has developed antibiotic resistance (AMR). Among all, the most compelling antibiotic resistance mechanism is production of -lactamases enzymes by this microorganism. Over the course of time -lactamase has evolved more than 1300 distinct enzymes. Amongst these most deleterious is extended spectrum beta lactamases (ESBL). ESBL producing Enterbacteriacaeae are responsible for a high number of deaths worldwide. These enzymes are considered challenging as they are difficult to be identified in the laboratory wShich cause delay in diagnosis and administration of appropriate antimicrobial therapy. The coexistence of ESBL with other antibiotic resistance gene is anothe...
Microbial Drug Resistance, 2003
A total of 1439 Escherichia coli isolates from sick animals were received from the Spanish Network of Veterinary Antimicrobial Resistance Surveillance (VAV) from 1997 to 2001. Antimicrobial susceptibility tests were performed and diminished susceptibility to cefotaxime and ceftazidime was identified in 2.5% and 2.8% of the isolates, respectively. b-lactamase characterization was carried out in the group of 20 E. coli isolates with both characteristics. The MIC ranges of different b-lactams showed by these 20 isolates were as follows (in mg/ml): ampicillin (64-.256), amoxicillin-clavulanic acid (4-64), ticarcillin (8-.128), cefazolin (32-.256), cefoxitin (4-.128), cefotaxime (1-64), ceftazidime (2-.64), ceftriaxone (0.5-64), imipenem (#0.06-0.25), and aztreonam (2-.32). TEM, SHV, CMY, and FOX b-lactamase genes were analyzed by PCR and sequencing. The b-lactamase genes detected were the following ones (number of isolates): bla TEM-1b (3), bla TEM-1a (1), bla TEM-30f (2), bla TEM-1b 1 bla CMY-2 (2), and bla SHV-12 (1). Sequences of the promoter and/or attenuator region of the chromosomal ampC gene were studied in all the 20 isolates. Mutations at position 242 or 232 were detected in 16 isolates and these mutations were associated with the presence of a TEM type b-lactamase in 6 isolates. Besides, a high variety of plasmidic b-lactamases was detected including TEM-30 and CMY-2. To our knowledge, this is the first time that TEM-30 b-lactamase has been detected in E. coli isolates of animal origin.
Occurrence of CTX-M-I Type β-lactamases Gene in Certain Gram Negative Bacteria
ABSTRACT: BACKGROUND: The CTX-M-type β-lactamases represent a group with a typical extended-spectrum β-lactamase (ESBL)-resistance phenotype. These enzymes, encoded by transferable plasmids. They have a preferential hydrolysis of Cefotaxime over Ceftazidime. The CTX-M-type β-lactamases have been described in species of Enterobacteriaceae and Pseudomonas aeruginosa. OBJECTIVE : This study was designed to investigate of the occurrence of CTX-M-I type in some Gram negative bacteria species isolated from clinical cases of in Iraq. METHODS: A group of Gram negative bacteria were isolated from different sources.Plasmid DNA extraction, and electrophoresis were performed. Using specific primers, CTX-M-I enzyme genes were amplified by PCR. RESULTS: Plasmid profile of the tested isolates reveals the presence of relatively large plasmids, their Wight was more than 10 kb some isolates posses’ 3-4 kb plasmids. The results of PCR amplification showed the presence of CTX-I genes. All isolates of Salmonella enterica serovar Typhimurium (100%) are negative for CTX-M-I gene as well as most of P. aeruginosa isolates (86.7%). In contrast, all of E. coli (100%) and most of Proteus Spp isolates were positive for CTX-M-I gene. CONCLUSION: CTX-M genes are predominant in E.coli followed by Proteus Spp. while Salmonella enterica serovar Typhimurium and P. aeruginosa isolates showed low incidence of blaCTX-M genes occurrence. The alarming situation with dissemination of CTX-M producing isolates highlights the need for their epidemiological monitoring and prudent use of antimicrobial agents.
Dissemination of CTX-M-Type Extended-Spectrum -Lactamase Genes to Unusual Hosts
Journal of Clinical Microbiology, 2005
A Citrobacter amalonaticus and a Morganella morganii producing the CTX-M-1 extended-spectrum -lactamase (ESBL) were isolated from an area where this enzyme is now widespread in Escherichia coli. This is the first report of CTX-M-1 in the former species. In both cases the ESBL determinant was possibly acquired by these unusual hosts in vivo, after coinfection with E. coli strains carrying conjugative plasmids encoding CTX-M-1.