Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Eighty-six strains of Shigella spp. were isolated during the dry season from stool samples of children under 5 years of age in Ifakara, Tanzania. The epidemiological relationship as well as the antimicrobial susceptibility and mechanisms of resistance to ampicillin, chloramphenicol, and co-trimoxazole were investigated. Four different epidemiological tools, pulsed-field gel electrophoresis (PFGE), repetitive extragenic palindromic (REP)-PCR, plasmid analysis, and antibiogram, were compared for typing Shigella strains. Seventy-eight (90%) strains were Shigella flexneri and were distributed into four groups, by either PFGE or REP-PCR, with 51, 17, 7, and 3 strains. The four strains of Shigella dysenteriae belonged to the same group, and the four strains of Shigella sonnei were distributed in two groups with three and one strain each. Plasmid analysis showed a high level of heterogeneity among strains belonging to the same PFGE group, while the antibiogram was less discriminative. REP-PCR provided an alternative, rapid, powerful genotyping method for Shigella spp. Overall, antimicrobial susceptibility testing showed a high level of resistance to ampicillin (81.8%), chloramphenicol (72.7%), tetracycline (96.9%), and co-trimoxazole (87.9%). Ampicillin resistance was related to an integron-borne OXA-1-type beta-lactamase in 85.1% of the cases and to a TEM-1-type beta-lactamase in the remaining 14.8%. Resistance to co-trimoxazole was due to the presence of a dhfr Ia gene in all groups except one of S. flexneri, where a dhfr VII gene was found within an integron. Chloramphenicol resistance was associated in every case with positive chloramphenicol acetyltransferase activity. All strains were susceptible to nalidixic acid, ciprofloxacin, ceftazidime, cefotaxime, and cefoxitin. Therefore, these antimicrobial agents may be good alternatives for the treatment of diarrhea caused by Shigella in Tanzania.
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PMID:Typing and characterization of mechanisms of resistance of Shigella spp. isolated from feces of children under 5 years of age from Ifakara, Tanzania. 1048 63

Ninety beta-hemolytic Escherichia coli isolates associated with diarrhea in neonatal pigs from multiple farms in Oklahoma were investigated for known associated disease serotypes, virulence factors, ribotypes, and antimicrobial susceptibility phenotypes. Fifteen different serotypes were observed, with 58% of isolates belonging to groups that produce one of three major enterotoxins: O149, O147, and O139. Thirty percent of the swine E. coli isolates possessed a combination of F4 fimbriae and the heat-labile toxin and heat-stable toxin B enterotoxins. Seventy-three percent of the E. coli isolates were resistant to five or more antibiotics. Interestingly, 53% of swine E. coli isolates exhibited resistance to chloramphenicol (CHL), an antibiotic whose use in food animals has been prohibited in the United States since the mid-1980s. The cmlA gene, which encodes a putative CHL efflux pump, was detected by PCR in 47 of the 48 CHL-resistant isolates, and 4 of these also possessed the cat2 gene, which encodes a chloramphenicol acetyltransferase. The one CHL-resistant isolate that did not contain either cmlA or cat-2 possessed the flo gene, which confers resistance to both florfenicol and CHL. To determine whether CHL-resistant swine E. coli isolates represented dissemination of a clonal strain, all 90 isolates were analyzed by ribotyping. Seventeen distinct E. coli ribogroups were identified, with CHL resistance observed among the isolates in all except one of the major ribogroups. The identification of the cmlA gene among diverse hemolytic enterotoxigenic E. coli strains demonstrates its broad dissemination in the swine production environment and its persistence even in the absence of CHL selection pressure.
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PMID:Characterization of chloramphenicol resistance in beta-hemolytic Escherichia coli associated with diarrhea in neonatal swine. 1182 47

The evolution of antimicrobial resistance in Salmonella isolates causing traveler's diarrhea (TD) and their mechanisms of resistance to several antimicrobial agents were analyzed. From 1995 to 2002, a total of 62 Salmonella strains were isolated from stools of patients with TD. The antimicrobial susceptibility to 12 antibiotics was determined, and the molecular mechanisms of resistance to several of them were detected as well. The highest levels of resistance were found against tetracycline and ampicillin (21 and 19%, respectively), followed by resistance to nalidixic acid (16%), which was mainly detected from 2000 onward. Molecular mechanisms of resistance were analyzed in 16 isolates. In these isolates, which were resistant to ampicillin, two genes encoding beta-lactamases were detected: oxa-1 (one isolate) and tem-like (seven isolates [in one strain concomitantly with a carb-2]). Resistance to tetracycline was mainly related to tetA (five cases) and to tetB and tetG (one case each). Resistance to chloramphenicol was related to the presence of the floR and cmlA genes and to chloramphenicol acetyltransferase activity in one case each. Different genes encoding dihydrofolate-reductases (dfrA1, dfrA12, dfrA14, and dfrA17) were detected in trimethoprim-resistant isolates. Resistance to nalidixic acid was related to the presence of mutations in the amino acid codons 83 or 87 of the gyrA gene. Further surveillance of the Salmonella spp. causing TD is needed to detect trends in their resistance to antimicrobial agents, as we have shown in our study with nalidixic acid. Moreover, such studies will lead to better treatment and strategies to prevent and limit their spread.
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PMID:Mechanism of resistance to several antimicrobial agents in Salmonella Clinical isolates causing traveler's diarrhea. 1538 55

Eighty isolates of Shigella spp. (37 Shigella flexneri and 43 Shigella sonnei) from patients with travellers' diarrhoea were studied. Susceptibility tests revealed high levels of resistance, especially to ampicillin (65%), tetracycline (78%) and trimethoprim (75%), and particularly among the S. flexneri isolates. Dihydrofolate reductase 1 genes (dfrA1) were prevalent among the trimethoprim-resistant isolates, while oxa genes predominated among the ampicillin-resistant isolates. Chloramphenicol resistance was associated with production of chloramphenicol acetyltransferase, while nalidixic acid-resistant isolates had a single mutation in the gyrA gene. The results indicate a continuing need for resistance surveillance and rational use of antimicrobial agents.
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PMID:Analysis of the mechanisms of resistance to several antimicrobial agents in Shigella spp. causing travellers' diarrhoea. 1630 63

MM-3 was a live vaccine strain candidate for protecting neonatal piglets from diarrhea. Designed in the 1980s, a high degree of protection from colibacillosis was afforded to piglets in a challenge study and field trials. However MM-3 had a drawback of carrying the antibiotic resistance gene (chloramphenicol acetyltransferase gene, cat). The introduction of a host-plasmid balanced lethal system into the vaccine was a good idea to solve the problem. The lambda-Red recombination system was adopted in this study to realize the replacement of cat by aspartate-semialdehyde dehydrogenase gene (asd) in the plasmid pMM085. The new plasmid named pMMASD was introduced into an Escherichia coli strain chi6097 and Salmonella typhimurium chi4072 where the asd gene had been knocked out in their chromosomes. Cultured in an Erlenmeyer flask, expression levels of two antigens K88ac fimbriae and heat-labile enterotoxin B subunit (LTB) in cell lysate were similar among MM-3, chi4072(pMMASD) and chi6097(pMMASD). However, chi4072(pMMASD) possessed the more effective secretion mechanism to transport LTB enterotoxin into culture liquid. The relatively higher stability of pMMASD in Salmonella typhimurium chi4072 than that of pMM085 in MM-3 was determined both in vitro in the absence of selective pressure, and in vivo following oral inoculation. Oral immunization of BALB/c mice with chi4072(pMMASD) or chi6097(pMMASD) was sufficient to elicit IgA responses in mucosal tissues as well as systemic IgG antibody responses to the K88 fimbriae, while MM-3 failed to elicit specific antibody responses to K88 fimbriae in mucosal tissues. Among three live strains, only chi4072(pMMASD) could develop strong humoral responses against LTB enterotoxin. The results suggest that chi4072(pMMASD) is expected to be a promising live vaccine strain.
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PMID:Removal of antibiotic resistance of live vaccine strain Escherichia coli MM-3 and evaluation of the immunogenicity of the new strain. 1715 78