Transcript Bacteriology Practice Questions

A 5 year old boy is seen in the paediatric respiratory
clinic for regular review of his cystic fibrosis. He has a
productive cough and a specimen is forwarded to the
laboratory. Select the culture medium which would be
most appropriate to isolate Haemophilus influenzae from
this patient.
A) Blood agar
B) Chocolate agar
C) MacConkey agar
D) Mannitol salt agar
E) XLD agar
A 23 year old male student was recently admitted
with invasive meningococcal disease. He has
recovered but gives a history of a previous episode
of meningococcal septicemia when he was 15
years old. There is no history of other recurrent
infections.
Select the most likely immunodeficiency state.
A) Adenosine deaminase dificiency
B) C7 deficiency
C) Job’s syndrome (hyperimmunoglobulinaemia E,
defective chemotaxis)
D) Myeloperoxidase deficiency
E) Selective IgM deficiency
A 42-year-old wig manufacturer returned 5 days ago from Iran
where he was inspecting herds for raw material. He had initially
experienced only mild upper respiratory tract symptoms, but 2
days later was brought to the emergency room with fever, severe
dyspnea, cyanosis, and tachycardia. Blood cultures were drawn
and after 16 hours of incubation, the smears revealed large,
gram-positive rods with subterminal spores. The organism was
nonhemolytic on blood agar and nonmotile. What is the most
probable identity of this organism?
A. Clostridium tertium
B. Bacillus anthracis
C. Clostridium perfringens
D. Bacillus subtilis
E. Bacillus cereus
A previously normal, full-term infant developed bilateral
conjunctivitis at 2 weeks of age. The conjunctivitis was followed
by severe coughing, but the infant remained afebrile. When the
infant was 4 weeks old, a chest X ray showed bilateral
symmetrical interstitial infiltrates. The white blood cell (WBC)
count was 14,000/mm3 with 32% segmented neutrophils, 58%
lymphocytes, 2% monocytes, and 4% eosinophils. Which of the
following is the most probable infectious agent?
A. Chlamydia trachomatis
B. Streptococcus agalactiae
C. Haemophilus influenzae
D. Mycoplasma pneumoniae
E. Rickettsiae rickettsiae
The mucoid appearance of these organisms is related to
which property?
A. pilus
B. capsule
C. plasmid
D. peptidoglycan
E. cell membrane
Which of the following microorganisms is not matched correctly
with the appropriate isolation media?
A. Streptococcus pyogenes - XLD agar
B. Neisseria gonorrhoeae – Thayer-Martin agar
C. Legionella pneumophilia – Buffered charcoal yeast extract
D. Mycobacterium tuberculosis - Lowenstein-Jensen agar
E. Mycoplasma pneumoniae SP4 agar
Which of the following diseases and bacteria is matched up
incorrectly?
A. Otitis media – Streptococcus pneumoniae
B. Scarlet Fever – Streptococcus pyogenes
C. Gastritis – Heliobacter pylori
D. Lyme disease – Yersinia pestis
E. Urethritis – Chlamydia trachomatis
Which of the following is not true concerning diseases
caused by Staphylococcus aureus?
A. S. aureus is related to inflammation.
B. S. aureus can cause pneumonia
C. S. aureus can lead to acute bacterial endocarditis
D. S. aureus is a common cause of cystitis
This Gram stain of sputum shows predominantly:
A. Gram-positive cocci in clusters
B. Gram-positive rods in clusters
C. Gram-positive cocci in pairs
*
D. Gram-negative cocci in pairs
E. Gram-negative rods in chains
A midstream CCU specimen from a 30 year old woman
with dysuria was cultured quantitatively using a 0.001 ml
calibrated loop. After 48 hours 5 pink colonies had grown
on MacConkey agar and blood agar. Which one of the
following is the correct interpretation of this observation?
A. 500 colonies of Escherichia coli
B. 5,000 colonies of gram-negative bacilli
C. specimen is contaminated and a new specimen should
be obtained and sent to the laboratory
D. urinary tract infection is present
Characteristics of primary gonococcal disease include the fact
that:
A. it is always treatable with penicillin
B. it rarely occurs simultaneously with chlamydial urethritis in
men
C. it produces efficient immunity so that recurrent infections
rarely occur
D. it can be accurately diagnosed in males by a gram-stain of
urethral discharge
E. it can only occur in the lower urogenital tract due to specific
tissue tropisms of Neisseria gonorrhoeae
Evasion of phagocytosis by host cells plays a major role
as a virulence factor in which one of these bacterial
pathogens?
A. Streptococcus
B. Chlamydia
C. Mycobacterium
D. Legionella
E. Ehrlichia
Which virulence factor is respinsible for the persistent
cough in mycoplasmal pneumonia?
A. Endotoxin
B. P1 adhesin
C. Exotoxin A
D. Phospholipase C
E. IgA protease
What is the most common source of Shigella infections?
A. Contact with infected persons
B. Steamed rice
C. Undercooked chicken
D. Undercooked hamburger
E. Contaminated water
A toxoid vaccine is protective against which of these
infectious diseases?
A. Diphtheria
B. Meningococcal meningitis
C. Bubonic plague
D. Pneumococcal pneumonia
E. Cholera
A man presents with diffuse maculopapular rash over his body,
including palms and soles. Upon questioning he mentions that he
has had a sore in his mouth recently and that he has had oral sex
with a prostitute several times. Which of these conditions is most
likely present?
A. gonorrhea
B. syphilis
C. trichomoniasis
D. herpes
E. chancroid
Which lab test will confirm the diagnosis?
A. Gram stain of urethral discharge
B. darkfield microscopy of saliva
C. Measurement of antibody in serum
D. PCR for chlamydia
E. Bacterial culture on blood agar
Which of these bacteria is an obligate
anaerobe?
A.
B.
C.
D.
E.
Bacillus
Clostridium
Campylobacter
Pseudomonas
Ureaplasma
A child develops acute rheumatic fever following a
streptococcal pharyngitis. The mechanism of this
illness is related to which of the following?
A. Exotoxin that destroys heart valves
B. Autoimmune reaction
C. Endotoxin that causes blood clots
D. Bacterial growth in cardiac muscle
E. Concurrent viral myocarditis
A febrile patient with a clinical diagnosis of bacterial endocarditis has a positive
blood culture. Based on this gram-stained smear from a blood culture bottle,
the most likely bacterial cause of this infection is:
A. Staphylococcus
B. Corynebacterium
C. Streptococcus
D. Listeria
E. Bacillus
A patient with hospital-acquired pneumonia has a sputum gram stain that
shows the organisms in the photomicrograph at the upper left. The culture
grows an organism on MacConkey with the appearance as shown on the
upper right.
The gram stain shows:
Which of these organisms is most likely
represented in these illustrations?
A.
B.
C.
D.
E.
A.
B.
C.
D.
E.
gram-positive cocci in pairs
encapsulated gram-negative rods
Gram-negative diplococci
Gram-variable rods
No bacteria present
Klebsiella
Proteus
Bordetella
Legionella
Mycoplasma
Which one of the following specimens
should NOT be cultured for anaerobic
bacteria?
A. blood
B. feces
C. lung tissue
D. brain tissue
E. peritoneal fluid
Which one of the following is the primary function
of Protein A in Staphylococcus aureus?
A. It provides a structural framework for the protein
capsule.
B. It helps the organism attach to slick surfaces.
C. It binds antibodies.
D. It masks carbohydrate antigens on the cell
surface.
E. It mediates production of beta lactamase.
Clinical manifestations of diphtheria are
mediated primarily by which one of the
following processes?
A. interruption of protein synthesis
B. endotoxic shock
C. induction of autoantibodies
D. stimulation of natural killer cells
E. widespread intravascular hemolysis
Mycobacterium tuberculosis virulence is due
primarily to which one of the following properties?
A. Exotoxins that interfere with host cell metabolism
B. Capacity for intracellular growth in macrophages
C. Rapid growth in vitro and in vivo
D. Endotoxin
E. Immunoglobulin protease
Which one of the following is a correct statement about
the epidemiology and pathogenesis of Rocky Mountain
Spotted Fever?
A. The etiologic agent rarely occurs outside of Colorado,
New Mexico, Wyoming, and Utah.
B. Control of infection would be improved if rat and fleas
are exterminated in high risk areas.
C. The etiologic agent is a spirochete that lives in the
saliva of lone star ticks.
D. It is a mild, self-limited disease that rarely requires
antimicrobial treatment.
E. The etiologic agent replicates in endothelial cells
resulting in vasculitis.