Chapter 8 Streptococci, staphylococci and micrococci
Review questions
Please indicate which answers are true, and which are false.
8.1 Which of the
... [Show More] following statements on streptococci are true?
A some are Gram-positive and anaerobic T
B can be primarily differentiated by their haemolytic reactions on blood agar T
C can cause caries in the absence of sucrose F cant (THEY NEED SURCOSE AS A PREDISPOSING FACTOR)
D mutans-group streptococci cause caries T
E oral streptococci typically show B-haemolysis on blood agar F alpha-haemolysis
8.2 Staphylococcus aureus can be differentiated from S. epidermidis by:
A the coagulase test T (AUREUS +VE)
B protein A latex agglutination test T (SYNTHESIZED IN S. AURUES)
C manitol fermentation test T (AUREUS +VE)
D Gram stain F (BOTH GRAM POSITIVE)
E oxidase test F (BOTH -VE)
8.3 An 18-year-old male patient has a facial abscess from which a beta-lactamase-positive Staphylococcus aureus strain was cultured. This organism:
A is resistant to penicillin T
B is coagulase-positive T
C is β-haemolytic T
D may possess the ability to cause diarrhoea T
E may cause rheumatic carditis F (STREPTOOCOCCUS PYOGENES)
8.4 Common staphylococcal infections include:
A suppurative skin infections T
B food-poisoning T
C toxic shock syndrome T
D osteomyelitis T
E pharyngitis F (STREPTOOCOCCUS PYOGENES)
Chapter 9 LactobaciIIi, corynebacteria and propionibacteri
Review questions
Please indicate which answers are true, and which are false.
9.1 Lactobacilli:
A are saprophytic T (live on dead decaying organic matter; animals & vegetables)
B are mostly homofermenters T (65%)
C are aciduric and acidogenic T uric: survive well in acid / genic: form acids)
D are best grown in strict anaerobic conditions F facultative anaerobes but grow in microaerophilic conditions
E count in a saliva sample is by far the best indicator of cariogenic activity F no indication of caries activity (only 1% in oral cavity) useful for monitoring dietary profile
9.2 Corynebacterium diphtheriae:
A are Gram-positive club-shaped spore-bearing rods F (non-spore forming) (bacilli – pleomphs) bacillus and clostridium are spore forming
B contains metachromatic granules T (stain with Neisser methylene red granules)
C produces a toxin that is similar to endotoxin F exotoxin
D causes pharyngeal and skin infections T (live in throat)
E is transmitted by airborne droplets T
9.3 Toxin produced by Corynebacterium diphtheriae:
A is mediated by a lysogenic phage T
B is similar to endotoxin F exotoxin
C is a polypeptide T (subunit A: adenosine diphosphate ribosyl ting) protein
D inhibits protein synthesis T
E causes neurological symptoms T (affect nervous system & motor nerves of myocardium)
9.4 Propionibacteria:
A are Gram-negative coccobacilli F gram-positive rods , obligate anaerobic
B are the members of 'diphtheroids' T (because they are anaerobic , gram positive)
C are facultatively anaerobic F obligate anaerobic
D are exclusive to the oral cavity F skin (acne)
E are frequently associated with dental caries F may be isolated from plaque
Chapter 10 Actinomycetes, clostridia and Bacillus specie
Review questions
Please indicate which answers are true, and which are false. 10.1 Which of the following statements on clostridia are true?
A they are Gram-positive non-spore-forming rods F spore forming bacilli
B they are commonly found in soil T
C they are strict anaerobes T (but few are aerotolerant)
D they produce powerful endotoxins that cause nerve damage F exotoxins (gram + has no endotoxin)
E they are commensals in mammalian intestines T
10.2 With regard to gas gangrene:
A Clostridium perfringenes is the primary causative organism T
B it is common in agricultural and warfare injuries T
C high doses of penicillin and metronidazole alone are sufficient for the treatment F not alone + extensive debridement of wound – anti alpha toxin (high antibody dose)
D Gram-positive spore-bearing rods are often isolated from the infected sites F cannot be isolated – infected sites don’t have spores
E vascular damage facilitates the infections T
10.3 Which of the following statements on Bacillus anthracis are true?
A it bears a polyglutamic acid capsule that is antiphagocytic T
B it is anaerobic F facultative or strict aerobic
C it could be used in germ warfare T
D it causes pulmonary and cutaneous infections and food poisoning F does not cause food poisoning
E humans are the only known hosts F (zoonotic disease) humans are accident hosts
10.4 Which of the following statements on Actinomycetes are true?
A it is an eukaryote F prokaryote (true bacteria)
B it causes chronic granulomatous infections T
C it infrequently causes actimomycoses of the jaws after tooth extractions T
D infections are often sensitive to penicillins T
E infections are difficult to eradicate because of the endogenous nature T
10.5. Which of the following statements on tetanus toxin/toxoid are true?
A tetanus toxin is an endotoxin F exotoxin
B tetanus toxoid is derived from hyperimmune human gammaglobulin F derived from tetanospasmin produced by clostridium tetani ( globulin not gamma) (Ag not antibody) (tetanus toxoid is derived from tetanus toxin treated with formalin, incubated for one month at 37%)
C tetanus toxoid booster should be given once every 10 years T
D tetanus toxoid is a component of the DTP vaccine T
E tetanus toxin causes trismus T (lock jaw) [Show Less]