Chloramphenicol resistance

Florfenicol iahibited 91% of the 399 bacterial isolates at a concentration of 12.5 )J.g/mL (31). At the same concentration, chloramphenicol and thiamphenicol iahibited only 70% and 24% of the isolates, respectively. Other work has also confirmed the superior activity of fiorfenicol against chloramphenicol-resistant strains (32—35). More recendy it has been shown that fiorfenicol is active against E. coli strains that produce type I, II, or III CAT enzymes (36). 

The efficacy of florfenicol in vivo was determined by measuring the dose required to obtain values for protection from infection in 50% of the animals (PD q) against 10 chloramphenicol-resistant strains and two chloramphenicol-sensitive isolates. Florfenicol, chloramphenicol, and thiamphenicol were evaluated concurrendy against each strain. Against sensitive Enterobacter 50 subcutaneous and oral routes were similar for dorfenicol and... 

Rosetta BL21 Enhances expression of proteins having codons rarely used in E. coll (additional tRNAs encoded by chloramphenicol resistant plasmid)... 

LysS/LysE an additional chloramphenicol resistant plasmid carries the gene forT7 lysozyme under constitutively active promoters. T7 lysozyme inhibits the activity of T7 polymerase thereby reducing basal (uninduced) polymerase activity/ protein expression. LysE express higher levels of T7 lysozyme for tighter control. pLacI an additional chloramphenicol resistant plasmid carries the gene for high level production of the lac repressor to reduce basal expression. 

LysS, LysE and Lad are all available in conjunction with additional rare codon tRNAs on the same chloramphenicol resistant plasmid (see Rosettas strain). 

Typhoid fever caused by Salmonella typhi or S. paratyphi is an important and prevalent cause of continuous fever without localizing symptoms in the tropics. The diagnosis can be confirmed with a bloodculture. Response on therapy is often seen only after 3 days when the fever subsides. Chloramphenicol-resistant Salmonella typhi was first described in Vietnam in 1973. Its prevalence reached 95% in the 1970s and then decreased to 54% in the 1980s after cotrimoxazole became the treatment of choice. In the mid-1993, there was a dramatic increase in the number of strains of S. typhi, isolated in the hospital and from patients in the outbreaks, which are resistant to the three first-line antibiotics chloramphenicol, cotrimoxazol and ampicillin. This indicated that there was an urgent need for effective antibiotics for the treatment of typhoid fever. 

Spika J.S., S.H. Waterman, G.W. Hoo, M.E. St. Louis, R.E. Pacer, S.M. James, M.L. Bissett, L.W. Mayer, J.Y. Chiu, B. Hall, et al. (1987). Chloramphenicol-resistant Salmonella newport traced through hamburger to diary farms. A major persisting source of human salmonellosis in California. New England Journal of Medicine 316 565-570. 

Fig. 1. Outline of the strategy to construct GST-fused expression plasmids by the in vitro recombination-assisted method. Am, Gm, and Cm are abbreviations for ampicillin-, gentamicin-, and chloramphenicol-resistance, respectively. The figure also indicates the ccdB gene encoding a toxin targeting the co//essential DNA gyrase and the phage X recombination sites (attB, attP, attL, and attR).

Fig. 5.3. Schematic representation of die display vector pASKIntlOO. fl, fl replication origin cat, chloramphenicol resistance marker tetR, tetracycline repressor encoding gene tetP/O, tetracycline promotor/operator region colEl, ColEl replication origin intimin, truncated eaeA gene of EHEC 0157 H7. Unique Ava I (Sma I, Xma I) and Bam HI restriction sites allow die in-frame fusion of genes encoding various passenger domains, as described in furdier detail in Wentzel et al. [7].

Huys, G., K. Bartie, M. Cnockaert, et al. 2007. Biodiversity of chloramphenicol-resistant mesophilic heterotrophs from southeast Asian aquaculture environments. Res. Microbiol. 158 228-235. 

ImmEI—immune to colicin El, Ap —ampicillin-resistant, CmR—chloramphenicol resistance, Km —kanamycin-resistant, Tc —tetracycline-resistant. 

Kearsey, S.E., Craig, I.W., Altered ribosomal RNA genes in mitochondria from mammalian cells with chloramphenicol resistance. Nature 1981, 290, 607-608. 

Wallace, D.C., Clayton, D.A., Mitochondrial DNA of chloramphenicol-resistant mouse cells contains a single nucleotide change in the region encoding the 3 end of the large ribosomal RNA. 

Blanc, H., Adams, C.W., Wallace, D.C., Different nucleotide changes in the large rRNA gene of the mitochondrial DNA confer chloramphenicol resistance on two human cell lines. Nucleic Acids Res. 

Nakaya [224] reported the presence of chloramphenicol acetyl transferase in a strain of Ps. aeruginosa. The enzyme activity was reported to be low and no chloramphenicol esters were detected. R factor mediated resistance to chloramphenicol in pseudomonas strains has been reported by Witchitz and Chabbert [225], However, Ingram, Richmond and Sykes [205] failed to transfer the R factor mediated chloramphenicol resistance gene to Ps. aeruginosa from a strain of Klebsiella aerogenes. 

There have been reports of chloramphenicol-resistant H. influenzae from various countries, but there have been few cases (50). Outbreaks of chloramphenicol-resistant S. typhi have been observed in several countries (51,52). 

High-level chloramphenicol-resistant strains of N. meningitidis serogroup B were isolated from 11 patients in Vietnam and one patient in France. Resistance was due to the presence of the catP gene on a truncated transposon that has lost mobility because of internal deletions (53). 

Esterases in serum from rabbits and to a lesser extent humans can convert diacetyl chloramphenicol back to an active antibiotic. Therefore, in vitro findings may not accurately reflect the level of chloramphenicol resistance by chloramphenicol acetyltransferase-bearing bacteria in vivo, when growth media supplemented with serum are used (58). 

Kinmonth AL, Storrs CN, Mitchell RG. Meningitis due to chloramphenicol-resistant Haemophilus influenzae type b. BMJ 1978 1(6114) 694. 

Butler T, Linh NN, Arnold K, Pollack M. Chloramphenicol-resistant typhoid fever in Vietnam associated with R factor. Lancet 1973 2(7836) 983-5. 

Galimand M, Gerbaud G, Guibourdenche M, Riou JY, Courvalin P. High-level chloramphenicol resistance in Neisseria meningitidis. N Engl J Med 1998 339(13) 868-74. 

Ahn, C., CollinS Thompson, D., Duncan, C., and Sites, M.E. 1992. Mobilization and location of the genetic determinant of chloramphenicol resistance from Lactobacillus plantarum caTC2R. 

Morelli, L., Vescovo, M., and Bottazzi, V. 1983. Identification of chloramphenicol resistance plasmids in Lactobacillus reuteri and Lactobacillus acidophilus. Int. J. Microbiol. 1, 1-5. 

Plasmids contain the DNA encoding the recombinant toxin under control of the T7 promoter (14), and contain an ampicillin or chloramphenicol resistance gene. The latter is preferred for the preparation of proteins for clinical use, since patients allergic to penicillin might react to recombinant proteins purified from bacteria grown in the presence of ampicillin. Plasmids are stored at a concentration of 1 mg/mL in 0.01 M Tris-HCl, pH 8.0, and 1 mM EDTA at 4°C. 

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