Corynebacterium diphtheriae
From Wikipedia, the free encyclopedia
| Corynebacterium diphtheriae | |
|---|---|
| Scientific classification | |
| Domain: | Bacteria |
| Phylum: | Actinobacteria |
| Order: | Actinomycetales |
| Family: | Corynebacteriaceae |
| Genus: | Corynebacterium |
| Species: | C. diphtheriae |
| Binomial name | |
| Corynebacterium diphtheriae | |
Contents
Classification
Four subspecies are recognized: C. d. mitis, C. d. intermedius, C. d. gravis, and C. d. belfanti. The four subspecies differ slightly in their colonial morphology and biochemical properties, such as the ability to metabolize certain nutrients, but all may be toxigenic (and therefore cause diphtheria) or not toxigenic. C. diphtheriae produces diphtheria toxin which alters protein function in the host by inactivating the elongation factor EF-2. This causes pharyngitis and 'pseudomembrane' in the throat. The diphtheria toxin gene is encoded by a bacteriophage found in toxigenic strains, integrated into the bacterial chromosome.To accurately identify C. diphtheriae, a Gram stain is performed to show Gram-positive, highly pleomorphic organisms with no particular arrangement. Special stains like Alberts's stain and Ponder's stain are used to demonstrate the metachromatic granules formed in the polar regions. The granules are called as polar granules, Babes Ernst granules, volutin, etc. An enrichment medium, such as Löffler's medium, is used to preferentially grow C. diphtheriae. After that, a differential plate known as tellurite agar, allows all Corynebacteria (including C. diphtheriae) to reduce tellurite to metallic tellurium. The tellurite reduction is colormetrically indicated by brown colonies for most Cornyebacteria species or by a black halo around the C. diphtheriae colonies.
A low concentration of iron is required in the medium for toxin production. At high iron concentrations, iron molecules bind to an aporepressor on the beta bacteriophage, which carries the Tox gene. When bound to iron, the aporepressor shuts down toxin production.[1] Elek's test for toxogenicity is used to determine whether the organism is able to produce the diphtheria toxin.
Pathogenesis
In areas where diphtheria is endemic, C. diphtheriae in the nasopharyngeal passageways is common. Toxigenic strains in susceptible individuals can cause disease by multiplying and secreting diphtheria toxin into either skin or nasopharyngeal lesions. The diphtheritic lesion is often covered by a pseudomembrane composed of fibrin, bacteria, and inflammatory cells. Diphtheria toxin can be proteolytically cleaved into two fragments: an N-terminal fragment A (catalytic domain), and fragment B (transmembrane and receptor binding domain). Fragment A catalyzes the NAD+ -dependent ADP-ribosylation of elongation factor 2, thereby inhibiting protein synthesis in eukaryotic cells. Fragment B binds to the cell surface receptor and facilitates the delivery of fragment A to the cytosol.Sensitivity
The bacterium is sensitive to the majority of antibiotics, such as the penicillins, ampicillin, cephalosporins, quinolones, chloramphenicol, tetracyclines, cefuroxime, and trimethoprim.Genetics
The genome of C. diphtheriae consists of a single circular chromosome of 2,5 Mbp, with no plasmids.[2][3] The genome shows an extreme compositional bias, being noticeably higher in G+C near the origin than at the terminus.See also
References
- Nester, Eugene W. et al. (2004). Microbiology: A Human Perspective (Fourth ed.). Boston: McGraw-Hill. ISBN 0-07-247382-7.
- Cerdeño-Tárraga, A. M.; Efstratiou, A; Dover, L. G.; Holden, M. T.; Pallen, M; Bentley, S. D.; Besra, G. S.; Churcher, C; James, K. D.; De Zoysa, A; Chillingworth, T; Cronin, A; Dowd, L; Feltwell, T; Hamlin, N; Holroyd, S; Jagels, K; Moule, S; Quail, M. A.; Rabbinowitsch, E; Rutherford, K. M.; Thomson, N. R.; Unwin, L; Whitehead, S; Barrell, B. G.; Parkhill, J (2003). "The complete genome sequence and analysis of Corynebacterium diphtheriae NCTC13129". Nucleic acids research 31 (22): 6516–23. doi:10.1093/nar/gkg874. PMC 275568. PMID 14602910.
- Sangal, V; Tucker, N. P.; Burkovski, A; Hoskisson, P. A. (2012). "The draft genome sequence of Corynebacterium diphtheriae bv. Mitis NCTC 3529 reveals significant diversity between the primary disease-causing biovars". Journal of Bacteriology 194 (12): 3269. doi:10.1128/JB.00503-12. PMC 3370853. PMID 22628502.
External links
- CoryneRegNet—Database of Corynebacterial Transcription Factors and Regulatory Networks
- Corynebacterium diphtheriae genome
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
HOW I GOT CURED OF HERPES VIRUS.
ReplyDeleteHello everyone out there, i am here to give my testimony about a herbalist called Dr imoloa. i was infected with herpes simplex virus 2 in 2013, i went to many hospitals for cure but there was no solution, so i was thinking on how i can get a solution out so that my body can be okay. one day i was in the pool side browsing and thinking of where i can get a solution. i go through many website were i saw so many testimonies about dr imoloa on how he cured them. i did not believe but i decided to give him a try, i contacted him and he prepared the herpes for me which i received through DHL courier service. i took it for two weeks after then he instructed me to go for check up, after the test i was confirmed herpes negative. am so free and happy. so, if you have problem or you are infected with any disease kindly contact him on email drimolaherbalmademedicine@gmail.com. or / whatssapp --+2347081986098.
This testimony serve as an expression of my gratitude. he also have
herbal cure for, FEVER, BODY PAIN, DIARRHOEA, MOUTH ULCER, MOUTH CANCER FATIGUE, MUSCLE ACHES, LUPUS, SKIN CANCER, PENILE CANCER, BREAST CANCER, PANCREATIC CANCER, CHRONIC KIDNEY DISEASE, VAGINAL CANCER, CERVICAL CANCER, DISEASE, JOINT PAIN, POLIO DISEASE, PARKINSON'S DISEASE, ALZHEIMER'S DISEASE, BULIMIA DISEASE, INFLAMMATORY JOINT DISEASE CYSTIC FIBROSIS, SCHIZOPHRENIA, CORNEAL ULCER, EPILEPSY, FETAL ALCOHOL SPECTRUM, LICHEN PLANUS, COLD SORE, SHINGLES, CANCER, HEPATITIS A, B. DIABETES 1/2, HIV/AIDS, CHRONIC RESPIRATORY DISEASE, CARDIOVASCULAR DISEASE, NEOPLASMS, MENTAL AND BEHAVIOURAL DISORDER, CHLAMYDIA, ZIKA VIRUS, EMPHYSEMA, TUBERCULOSIS LOW SPERM COUNT, ENZYMA, DRY COUGH, ARTHRITIS, LEUKAEMIA, LYME DISEASE, ASTHMA, IMPOTENCE, BARENESS/INFERTILITY, WEAK ERECTION, PENIS ENLARGEMENT. AND SO ON.