MED BAC 2

Here is a 50-question practice exam modeled after your quiz materials and pathogen list. I’ve broken it down by section to match the way these are typically tested.

🧪 Section 1: Gram-Negative Diplococci & Coccobacilli

  1. Which Neisseria species is able to ferment both glucose and maltose?

  2. A patient presents with a painful genital ulcer. Microscopic exam shows Gram-negative coccobacilli in a "school of fish" arrangement. What is the likely pathogen?

  3. Which organism requires both X (heme) and V (NAD) factors to grow on agar?

  4. Neisseria gonorrhoeae is often identified in men by observing GNDC inside which type of host cell?

  5. What is the specific agar used to grow Bordetella pertussis that results in "mercury drop" colonies?

  6. True or False: Neisseria meningitidis is always considered a strict pathogen and is never part of the normal flora.

  7. The "satellite phenomenon" occurs when Haemophilus influenzae grows near which other bacterium on blood agar?

  8. Which virulence factor in Neisseria species is responsible for cleaving secretory antibodies at mucosal surfaces?

  9. Which fastidious Gram-negative rod is a zoonotic pathogen that causes "undulant fever"?

  10. Describe the characteristic "twitching motility" seen in N. gonorrhoeae. What structure allows this?

🦠 Section 2: Gram-Positive Rods (Aerobic)

  1. Which GPR is famous for "umbrella motility" when grown at room temperature?

  2. A "Medusa head" colony on Sheep Blood Agar is characteristic of which organism?

  3. Which pathogen is a common "cold survivor" and can grow in temperatures as low as 4°C?

  4. What is the primary clinical sign of a respiratory Corynebacterium diphtheriae infection?

  5. Which non-spore-forming GPR is an essential part of the healthy vaginal microbiota?

  6. Bacillus anthracis is unique among most bacteria because its capsule is composed of what?

  7. In the Lab, Listeria monocytogenes will show a positive result for which test that it shares with Group B Strep?

  8. Which GPR has a "bamboo plant" appearance under the microscope?

  9. How is Listeria able to move from cell to cell without entering the extracellular space?

  10. Which organism produces a toxin that inhibits host protein synthesis, leading to "bull neck" lymphadenopathy?

💩 Section 3: The Enterics (Enterobacteriaceae)

  1. Which enteric organism produces a metallic green sheen on EMB agar?

  2. Which rapid lactose fermenter is known for being highly mucoid and non-motile?

  3. A stool sample on MacConkey agar shows colorless colonies. A TSI slant shows an alkaline/acid (K/A) reaction with H2S production (black). What is the bug?

  4. Which organism is the #1 cause of UTIs in the United States?

  5. Serratia marcescens is easily identified at room temperature by what physical characteristic?

  6. Which "true pathogen" is non-motile and causes bloody/mucoid diarrhea with a very low infectious dose?

  7. Describe "swarming motility" and name the genus that exhibits it.

  8. Which enteric is associated with "rice-water stools"?

  9. Escherichia coli O157:H7 is most commonly associated with what type of food?

  10. Which organism hides in the gallbladder of asymptomatic chronic carriers?

  11. What color would Salmonella colonies be on Hektoen Enteric (HE) agar?

  12. Which bacterium is the causative agent of the Black Plague and shows "safety pin" staining?

  13. True or False: All Enterobacteriaceae are Oxidase positive.

  14. Which organism produces a "burnt chocolate" odor in culture?

  15. What is the clinical significance of Proteus species in relation to kidney stones?

🌊 Section 4: Non-Fermenters & Curved Rods

  1. Which non-fermenting rod produces a blue-green pigment called pyocyanin?

  2. A patient with Cystic Fibrosis has a persistent lung infection. The colonies on agar smell like "corn tacos" or grapes. What is the pathogen?

  3. Which curved rod requires 42°C for optimal growth and is a microaerophile?

  4. Helicobacter pylori survives the stomach’s acid by producing large amounts of which enzyme?

  5. Which Vibrio species requires salt (halophilic) and is often associated with raw oysters?

  6. What is the characteristic Gram stain morphology of Campylobacter jejuni?

  7. A "string test" is used to help identify which genus?

  8. Which non-fermenter is commonly found in hospital sinks and is highly resistant to many antibiotics?

  9. Pseudomonas aeruginosa produces which type of biofilm that makes it especially dangerous for CF patients?

  10. Vibrio vulnificus is particularly life-threatening to patients with which underlying condition?

🧪 Section 5: Matching & Clinical Scenarios

  1. Match the smell to the bug:

    • A. Grapes/Corn Tacos

    • B. Burnt Chocolate

    • C. Bleach/Mousy

    • D. Dirt-like

    • (Bugs: Proteus, Pseudomonas, Burkholderia, Haemophilus)

  2. Match the Disease to the Bug:

    • A. Whooping Cough

    • B. Typhoid Fever

    • C. Undulant Fever

    • D. Chancroid

    • (Bugs: Brucella, B. pertussis, S. Typhi, H. ducreyi)

  3. A neonate has meningitis. The lab reports a Gram-positive coccobacillus with a narrow zone of beta-hemolysis. What is it?

  4. A traveler returns from a country with poor sanitation and has profuse, watery diarrhea. The stool has no blood. What is the likely toxin involved?

  5. Which media is specifically used to select for Vibrio species and turns yellow if sucrose is fermented.

Section 1: Gram-Negative Diplococci & Coccobacilli

  1. N. meningitidis (N. gonorrhoeae only ferments glucose).

  2. Haemophilus ducreyi (causes Chancroid).

  3. Haemophilus influenzae (specifically Type b/Hib).

  4. Neutrophils (Polymorphonuclear leukocytes).

  5. Bordet-Gengou (or charcoal-based medium).

  6. False (It can be normal flora in the upper respiratory tract).

  7. Staphylococcus aureus (supplies the V factor).

  8. IgA Protease.

  9. Brucella species (B. melitensis).

  10. Pili (allows for attachment and "crawling" movement).

Section 2: Gram-Positive Rods (Aerobic)

  1. Listeria monocytogenes.

  2. Bacillus anthracis.

  3. Listeria monocytogenes.

  4. Gray Pseudomembrane in the throat.

  5. Lactobacillus.

  6. Protein (Poly-D-glutamic acid), whereas most are polysaccharide.

  7. CAMP test.

  8. Bacillus anthracis.

  9. Actin Rockets (polymerizing host actin).

  10. Corynebacterium diphtheriae (Diphtheria toxin).

Section 3: The Enterics (Enterobacteriaceae)

  1. Escherichia coli.

  2. Klebsiella pneumoniae.

  3. Salmonella.

  4. Escherichia coli (Uropathogenic E. coli/UPEC).

  5. Red Pigment (Prodigiosin).

  6. Shigella.

  7. Swarming motility; Proteus.

  8. Vibrio cholerae (Note: Vibrio is often studied with enterics but is taxonomically different).

  9. Undercooked ground beef (also raw milk/juice).

  10. Salmonella Typhi.

  11. Green with black centers (H2S production).

  12. Yersinia pestis.

  13. False (They are Oxidase negative).

  14. Proteus mirabilis.

  15. Urease production raises urine pH, causing calcium/magnesium stones to form.

Section 4: Non-Fermenters & Curved Rods

  1. Pseudomonas aeruginosa.

  2. Pseudomonas aeruginosa.

  3. Campylobacter jejuni.

  4. Urease.

  5. Vibrio parahaemolyticus.

  6. "Seagull wings" or S-shaped/spirals.

  7. Vibrio (V. cholerae is strongly positive).

  8. Burkholderia cepacia (or Pseudomonas).

  9. Alginate (slime layer).

  10. Liver disease (hemochromatosis/cirrhosis).

Section 5: Matching & Clinical Scenarios

  1. A-Pseudomonas; B-Proteus; C-Haemophilus; D-Burkholderia.

  2. A-B. pertussis; B-S. Typhi; C-Brucella; D-H. ducreyi.

  3. Listeria monocytogenes.

  4. Cholera Toxin (Enterotoxin that increases cAMP).

  5. TCBS Agar (Thiosulfate Citrate Bile Salts Sucrose).