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MLT-Aerobic GP Rod
Microbiology
Question | Answer |
---|---|
What are the clinically important GPR? | 1.Spore-forming: Bacillus, Clostridium(anaerobe) 2.Non spore-forming: Corynebacterium, Listeria |
What are the sequence to differentiate GPR? | 1.Gram stain morphology 2.Catalase reaction 3.Beta-hemolysis with sheep blood agar 4.Aerobic sporulation |
Which GPR is a irregular rod? | 1.Corynebacteria 2.Catalase + 3.Non β-haemolytic (Some can be α-haemolytic) |
Which GPR are regular rods? | 1.Bacillus(catalase +, beta-hemolytic, except B. anthracis) 2.Listeria monocytogenes(catalase +, beta-hemolytic) 3.Erysipelothrix(catalase -, non beta-hemolytic) |
What are the clinically important Bacillus to Human? | 1B. anthracis 2.B. cereus |
Bacillus only form endospores in the presence of ? | Oxygen |
Whats makes the Bacillus so special ? | Heat and chemical resistant |
What are the application of Bacillus? | 1.Validation of autoclave and disinfectants 2.Production of antibiotics 3.Production of vitamins |
How Bacillus can be used to validate autoclave? | 1.As biological indicator 2.B. stearothermophilus can survive even at 75℃ |
How Bacillus can be as control for ethylene oxide sterlisation? | Bacillus spores are chemical resistant |
What antibiotics are produced by Bacillus? | 1.B.licheniformis –bacitracin 2.B. polymyxa –polymyxin B |
What vitamins are produced by Bacillus? | B. megaterium –B12and B2 |
What are the background for B. anthracis? | 1.Colony on sheep blood agar: large (4-5mm), flat, and white to gray with irregular edges 2.no β-haemolysis 3.Non-motile |
What are the virulent factor of B. anthracis? | 1. Capsular protein-antiphagocytic 2.Exotoxins -> edema |
Which three portal entry of B. anthracis infection and its mortality rate? | 1.Cutaneous: mortality ~20% 2.Gastrointestinal 3.Pulmonary: mortality 100% |
What are the specimen for B. anthracis? | Pus or tissue samples |
How to identify B. anthracis? | 1.Gram positive rod 2.Easy to culture on standard blood or nutrient agar 3.Gray to white and non-haemolytic colonies 4.motility - 5.catalase + 6.Penicillin + 7.endospore + |
How to treat B. anthracis? | 1.Intravenous penicillin for early infection. 2.Ciprofloxacin as alternative for penicillin-allergic 3.Prophylaxis with ciprofloxacin for the late stage or during outbreak 4.Vaccination |
Which species in Bacillus would cause food poisoning? | B. cereus 1.due to survival of the endospores from the improper cooking process 2.after long RT storage, spore germinates and bacteria produce endotoxin |
How to identify B. cereus? | 1.Gram + rod 2.Gray to Green large colonies, Beta-hemolytic on Blood agar 3.motility + 4.Penicillin - |
Which is the most important pathogenic species in Corynebacterium? | Corynebacterium diphtheriae |
What are the 4 subspecies of Corynebacterium diphtheriae? | 1.C. diphtheriae gravis 2.C.diphtheriae intermedicus 3.C. diphtheriae mitis 4.C. diphtheriae belfanti |
Where does the diphtheria toxic come from? | 1.Bacteriophage 2.it infects C. diphtheriae and transfers toxin genes 3. C. diphtheriae will then become toxigenic strain |
What would be caused by C. diphtheriae? | 1.local lesion in throat 2.formation of pseudomenbrane that obstruct breathing 3.lead to death due to respiratory distress |
What would be the specimen for C. diphtheriae? | Swab from throat lesion |
How to identify Corynebacterium? | 1. Gram + rod 2.Chinese character '八' 3.Non motile 4.Non or alpha hemolytic |
How to identify C. diphtheriae? | 1.Gram + rod 2.Chinese character 3.Tinsdale Agar: selective and differential |
What can be observed if C. diphtheriae on Tinsdale agar? | 1.C.diphtheriaecan reduce potassium tellurite into a metallic telluriteand forms 2.A dark (black to brown) halo surrounding the colonies |
What others can also produce dark colony on Tinsdale agar? | Staphylococci Proteus can also produce black colonies but no halo |
How to test if the C. diphtheriae is toxigenic? | 1.Elek Assay 2.Paper strip saturated with diphtheria antitoxin in molten agar at 55℃ 3.Positive: Development of an agar precipitin line at 45ºangleto the strip within 1-2 days of incubation |
How to treat C. diptheriae infection? | 1.Vaccine 2.Penicillin or Erythromycin+antitoxin |
What is the human pathogen of Listeria? | Listeria monocytogenes |
What is the basic info of Listeria? | 1.Gram + rod 2.Short single rod, sometimes in chain 3.Non spore forming 4.Flagella at RT , motile at 30C |
What can be the specimen for L. monocytogenes? | blood, CSF, amniotic fluid, genital tract swabs |
How to identify L. monocytogenes? | 1.Gram + rod 2. Catalase + 3.CAMP + 4.Round translucent colony with narrow zone of β-haemolysis |
What does the CAMP test do? | 1.Presumptive identification of Group B Streptococcus (Streptococcus agalactiae), the only beta-hemolytic Streptococcus 2. GBS produce CAMP factor to enhance the beta-hemolysis effect of Staphylococcus aureus. 3. |
How to treat L. monocytogenes infection? | 1. Penicillin or Ampicillin 2. Vancomycin if Penicillin allergy 3. Listeria is innately resistant to cephalosporin I, II and III |