No Spicy Food for Me

No Spicy Food for Me!
Jack was thankful he had declined the offer of spicy Mexican food with his coworkers. The pain was worse, burning from his navel to his breastbone. It always peaked at night and when he was hungry. “It's just the stress from work,” Jack told himself.
Jack chewed up a handful of Tums, and made toast and tea for his late dinner. Despite the antacids and bland meal, Jack's gastric distress intensified. Two hours later, Jack vomited and was terrified to see bright red blood mixed in with his regurgitated toast. He drove immediately to the hospital.
After examining Jack, Dr. McAfee said, “You have all the symptoms of a gastric ulcer: persistent burning belly pain worsening at night, weight loss, and nausea. Your experience tonight plus the dark stools you reported means the ulcer is bleeding. I'm going to order a test to confirm this diagnosis so we can get you started on antibiotics.”
Jack responded with surprise. “You said I had an ulcer, not an infection. What do I need antibiotics for?”
Dr. McAfee explained that most gastric ulcers are the result of a bacterial infection (Figure a). As the microorganism thrives in the mucus layer protecting the stomach surface, its activity can weaken the coating. Sensitive stomach tissues are exposed to both acid and the bacteria, which degrade the lining and cause ulcer formation.
a. Helicobacter pylori, the microbe that causes most gastric ulcers

1. Which microorganism is infecting Jack and causing his gastric ulcer? Describe its morphology.
2. REVIEW: What is the pH of the stomach acid irritating the lining of Jack's stomach?
   In the morning, Jack underwent an endoscopy, a procedure involving the insertion of a tube with a tiny camera down the esophagus and into the stomach. After directly viewing the damaged lining, the physician performed a biopsy by collecting a small tissue sample near the ulcer and examining it.
   At his follow-up appointment, the physician explained that Jack's CLO test was positive, indicating that his ulcer was caused by infection (Figure b). His biopsied tissue was inserted into a small container of urea agar mixed with the pH indicator, phenol red. Bacteria infecting the tissue used urease to convert the urea into carbon dioxide and ammonia, raising the pH and changing the indicator from yellow to hot pink.
   b. The CLO test packet
3. Examine the CLO test packet in Figure b. Does the indicator show the pH as acidic or basic? How do you know?
   Jack's physician wrote a prescription for 2 weeks of antibiotics plus Protonix, a drug to inhibit acid pumps in his stomach. The doctor explained that the infecting bacteria can also raise the pH in the stomach just as they did in the CLO test. Gastric tissues compensate by secreting more acid, which in turn aggravates the ulcer. “So doctor, if the excess acid can destroy my stomach lining, why doesn't it kill the infecting bacteria?” Jack asked.
   “This bacterial species is adapted to the harsh conditions of your stomach and capable of withstanding the low pH that kills most other pathogens,” answered the doctor. “Finish your prescriptions and you'll be in good shape…remember, stress and spicy food can aggravate an ulcer, but the bacteria caused it.”
4. INVESTIGATE: Which antibiotic was likely prescribed to treat Jack's ulcer?
5. What microorganisms compose the normal microbiota of the stomach? Why?
   Think critically and try the interactive case study related to pathogens discussed in this chapter.