Micro bacteriology MCQS Flashcards
1- The localized nature of S. aureus lesions is due to:
a- Adhesins
b- Protein A
c- Staphylocoagulase
d- Staphylokinase
e- Catalase
c- Staphylocoagulase
2- The following statements about S. aureus food poisoning are true EXCEPT:
a- It is caused by enterotoxins.
b- The source of contamination is usually a carrier.
c- The incubation period is 24-36 hours.
d- Food contains preformed toxin.
e- The responsible toxin acts as a superantigen.
c- The incubation period is 24-36 hours.
3- MRSA isolates are treated empirically by:
a- Erythromycin
b- Vancomycin
c- Clindamycin
d- Cephalosporins
e- Tetracycline
b- Vancomycin
4-The most Important factor enabling S. epidermidis to colonize prosthetic devices Is:
a- Production of coagulase
b- Resistance to many antibiotics
c- Production of glycocalyx
d- Production of exotoxin
e- Production of clumping factor
c- Production of glycocalyx
1- The following are virulence factors for S. pyogenes EXCEPT:
a- Fibronectin binding protein
b- M protein
c- Hyaluronic acid capsule
d- Fibrinolysin
e- Coagulase
e- Coagulase
2- Acute rheumatic fever:
a- Is diagnosed by elevated anti-DNAse antibodies
b- Usually follows streptococcal skin infections
c- Is caused by streptococcal invasion of the cardiac valves
d- Should be followed by chemoprophylaxis to prevent further attacks
e- Develops 3-6 months following an acute streptococcal disease
d- Should be followed by chemoprophylaxis to prevent further attacks
3- Which of the following procedures is most likely to reduce the incidence of group B streptococcal sepsis in infants:
a- Intrapartum antibiotic treatment
b- Use of a polysaccharide vaccine
c- Screening of pregnant females in the first trimester
d- Identification of possible high risk births
e- Antibiotic treatment of the newborn
a- Intrapartum antibiotic treatment
4- After extraction of a tooth, a student with history of congenital heart disease was diagnosed as having subacute bacterial endocarditis. The most likely organism causing this infection is:
a- Staphylococcus aureus
b- Staphylococcus epidermidis
c- Streptococcus pneumoniae
d- Viridans streptococci
e- Enterococci
d- Viridans streptococci
5- If a quellung test was done on the following bacterial isolates, which one would you expect to be positive?
a- S. pneumoniae
b- S. pyogenes
c- S. aureus
d- Viridans streptococci e- S. epidermidis
a- S. pneumoniae
1- Enterococci differ from streptococci in the following EXCEPT:
a- They can grow at 45°C.
b- They are salt tolerant.
c- They tolerate bile salts
d- They hydrolyze the polysaccharide esculin. e- They are catalase negative
e- They are catalase negative
1- All the following are characters of the genus Neisseria EXCEPT:
a- Gram negative diplococci
b- Kidney shaped
c- Aerobic
d- Oxidase negative
e- Including commensals and pathogenic species
d- Oxidase negative
3- In adult females, gonococci infect the following sites EXCEPT:
a- The cervix
b- The vagina
c- Urethra
d- Vulva
e- Rectum
b- The vagina
2- N. gonorrhoeae is a fastidious pathogen found in sites often contaminated with normal flora. The best medium for isolation is:
a- Blood agar
b- Loeffler’s medium
c- Thayer-Martin medium
d- Thiosulphate citrate bile salts sucrose medium
e- Lowenstein Jensen medium
c- Thayer-Martin medium
1- The following statements concerning B. anthracis are correct EXCEPT:
a- It is a Gram-positive spore forming bacillus.
b- It causes a zoonotic disease.
c- It is a typical biological weapon.
d- The toxin is its only virulence factor.
e- It can cause pneumonia or skin lesions.
d- The toxin is its only virulence factor.
4- The most important virulence factor in N. meningitidis is:
a- IgA protease
b- Outer membrane protein
c- Pili
d- The polysaccharide capsule
e- Lipid A
d- The polysaccharide capsule
2- The emetic form of B. cereus food poisoning is characterized by the following EXCEPT:
a- It resembles S. aureus food poisoning
b- It has a short incubation period.
c-The incriminated food is usually fried rice.
d- It is due to heat labile enterotoxin.
e- It is manifested by vomiting and abdominal cramps.
d- It is due to heat labile enterotoxin.
3- The following is true about Clostridium perfringens EXCEPT:
a- It causes gas gangrene.
b-It causes food poisoning.
c-It produces an exotoxin that degrades lecithin.
d-Endotoxin is a virulence factor of the organism,
e-It is one of the indicators of faecal pollution of water.
d-Endotoxin is a virulence factor of the organism,
4- Active immunization against tetanus is given to the following EXCEPT:
a- Pregnant females
b- Infants in the first year of life
c- Military personnel
d- Wounded individuals with history of vaccination within 2 years
e- Routinely every 10 years
d- Wounded individuals with history of vaccination within 2 years
5- Symptoms of botulism are due to:
a- Invasion of the gut epithelium by C. botulinum
b- Secretion of an enterotoxin
c- Ingestion of a neurotoxin
d- Endotoxic shock
e- Activation of cyclic AMP
c- Ingestion of a neurotoxin
6- A patient presents with severe colitis associated with an overgrowth of C. difficile in the bowel. The most likely cause of this condition is:
a- Botulinum food poisoning
b- A stomach ulcer
c- Compromised immune system
d- Antibiotic therapy
e- Mechanical blockage of the large intestine
d- Antibiotic therapy
1- The following bacteria belong to Enterobacteriacae family EXCEPT:
a- Escherichia
b- Shigella
c- Yersinia
d- Salmonella
e- Pseudomonas
e- Pseudomonas
2- E. co//that produces shiga-like toxin is:
a- Enterotoxigenic E. coli
b- Enterohaemorrhagic E. coli
c- Enteroinvasive E. coli
d- Enteroaggregative E. coli
e- Enteropathogenic E. coli
b- Enterohaemorrhagic E. coli
3- Klebsiella species are characterized by all the following EXCEPT:
a- Resistant strains are important agents of nosocomial infections.
b- They may cause urinary tract infection and neonatal sepsis,
c- They have a thick polysaccharide capsule.
d- Some species may cause rhinoscleroma.
e- They are indole positive.
e- They are indole positive.
4- The following statements describing Salmonella species are all correct EXCEPT:
a- They are gram-negative bacilli.
b- They grow as pink colonies on MacConkey and DCA media,
c- They are urease-negative.
d- They cause food poisoning.
e- They cause enteric fever.
b- They grow as pink colonies on MacConkey and DCA media,
5- Concerning the Widal test:
a- It is a toxin-antitoxin neutralization test.
b- It is positive on the third day of fever.
c- Early treatment leads to high titres.
d- Titre >1:160 against O and H antigens indicates active infection,
e- Titres up to 1:160 are considered normal.
d- Titre >1:160 against O and H antigens indicates active infection,
6- TAB vaccine is used for protection against:
a- Meningitis
b- Enteric fever
c- Tuberculosis
d- Diphtheria
e- Tetanus
b- Enteric fever
7- Regarding Shigella dyenteriae all the following statements are correct EXCEPT:
a- It is a member of Enterobacteriaceae.
b- It produces a toxin that may result in renal failure,
c- It grows on MacConkey’s medium as colourless colonies,
d- Serological identification depends on 0 and H antigens,
e- It causes bloody diarrhoea.
d- Serological identification depends on 0 and H antigens,
8- Proteus can be differentiated from Salmonella by being:
a- Gram-negative bacilli
b- Non-lactose fermenter
c- Urease-positive
d- H2S-positive
e- Motile
c- Urease-positive
1- The following statements refer to H. influenzae EXCEPT:
a- It is pleomorphic.
b- Its major virulence factor is IgA protease.
c- It requires both X-factor and V-factor for growth.
d- It is one of the major causes of meningitis.
e- It causes infection mainly in children between 6 months and 6 years of age.
b- Its major virulence factor is IgA protease.
2- Haemophilus influenzae type b:
a- Is a Gram-positive rod
b- Is a common cause of influenza
c- Can grow alone on blood agar
d- Has a polysaccharide capsule
e- Is the most common cause of urinary tract infection
b- Is a common cause of influenza
3- The vaccine against H. influenzae is:
a- Live attenuated H. influenzae
b- Killed H. influenzae
c- Toxoid derived from H. influenzae
d- Polysaccharide derived from H. influenzae
e- Polysaccharide derived from H. influenzae conjugated to a protein
e- Polysaccharide derived from H. influenzae conjugated to a protein
4- A 2-year-old child came to the emergency room with high fever and breathing difficulty. Clinical investigation revealed inflammatory
swelling of the epiglottis. Which of the following organisms is the most likely causative organism?
a- Haemophilus influenzae
b- Haemophilus ducreyi
c- Haemophillus aegyptius
d- Bordetella pertussis
e- Neisseria meningitidis
a- Haemophilus influenzae
5- Chancroid is characterized by the following EXCEPT:
a- It is caused by Haemophilus ducreyi.
b- It is a sexually-transmitted disease.
c-It manifests as a genital ulcer.
d-It is hard and painless.
e- It is accompanied by enlarged inguinal lymph nodes.
d-It is hard and painless.
1- Peritonitis caused by B. fragilis is acquired:
a- Faeco-orally
b- By ingestion of contaminated food
c- As a complication of food poisoning
d- As an endogenous infection
e- By a puncture wound
d- As an endogenous infection
2- Which of the following is correct about B. fragilis:
a- It is the most likely organism to cause gastroenteritis following antibiotic treatment.
b- It is sensitive to penicillin.
c- It is the predominant organism in the human gastrointestinal tract,
d- It may cause flaccid paralysis which may lead to respiratory arrest,
e- It is the most common organism causing urinary tract infection.
c- It is the predominant organism in the human gastrointestinal tract,
3- Fusobacterium contributes to the pathogenesis of:
a- Acne vulgaris
b- Necrotizing fasciitis
c- Bacterial vaginosis
d- Vincent’s angina
e- Honeymoon cystitis
d- Vincent’s angina
1- M. tuberculosis can be isolated by culture on:
a- Blood agar
b- Loeffler’s serum
c- Modified Thayer-Martin
d- Thiosulfate citrate bile salt sucrose (TCBS) agar
e- Lowenstein-Jensen medium
e- Lowenstein-Jensen medium
2- As regards the diagnosis of tuberculosis, the following are correct EXCEPT:
a- Three morning sputum samples should be examined.
b- Tuberculin test may give false positive and false negative results,
c- Detection of acid-fast bacilli in smears provides early presumptive diagnosis.
d- Liquefaction of tenacious samples is required before culture,
e- Growth on Lowenstein-Jensen medium appears after 48-72 hours.
e- Growth on Lowenstein-Jensen medium appears after 48-72 hours.
3- Regarding tuberculin test:
a- It depends on immediate hypersensitivity,
b- It depends on presence of sensitized Th2 cells,
c- A wheal and flare is considered positive,
d- People vaccinated with BCG give a negative result,
e- It is read after 48-72 hours.
e- It is read after 48-72 hours.
4- Treatment of tuberculous disease:
a- Is initiated with a single first line chemotherapeutic agent
b- Usually requires prolonged bed rest and surgery
c- Is continued until tuberculin test reverts to negative
d- Always results in negative sputum cultures and clinical cure within 3 weeks
e- Always necessitates the use of combined, prolonged drug therapy
e- Always necessitates the use of combined, prolonged drug therapy
5- BCG vaccine, used for the prevention of tuberculosis is:
a- Heat killed vaccine
b- Formalin inactivated vaccine
c- Living attenuated vaccine
d- Recombinant vaccine
e- Bacterial toxoid prepared from M. tuberculosis
c- Living attenuated vaccine
6- Which of the following organisms cannot be grown on artificial media?
a- S. pyogenes
b- S. epidermidis
c- K. pneumoniae
d- Salmonella Typhi
e- M. leprae
e- M. leprae
7- Tuberculoid leprosy has the following features EXCEPT:
a- Lepromin test is positive.
b- The course of the disease is benign.
c- Cell-mediated immunity is intact.
d- Acid fast bacilli are few in tissue smears,
e- Th2-type response is dominant.
e- Th2-type response is dominant.
1- All the following statements about primary syphilis are correct EXCEPT:
a- It manifests as a painless ulcer.
b- The characteristic lesion contains no organisms.
c- It can be diagnosed serologically during the late stage,
d- It is caused by Treponema pallidum.
e- It can be treated by penicillin.
b- The characteristic lesion contains no organisms.
2- Direct detection of T. pallidum cannot be done from:
a- Chancre
b- Mucous patches
c- Chondyloma lata
d- Gumma of internal organs
e- Any of the above
d- Gumma of internal organs