Gastrointestinal Disorders Quiz

Gastrointestinal Tract Study Notes

• The gastrointestinal tract includes the esophagus, stomach, small intestines (duodenum, jejunum, ileum), large intestines (cecum, colon, rectum), and anus.
• The small intestines contain the duodenum, jejunum, and ileum.
• The large intestines include the cecum, colon, and rectum.
• The gastrointestinal tract is composed of different organs, each with specific functions in digesting and absorbing nutrients.
• Different parts of the tract have normal flora.

Terms Related to Inflammation in the Gastrointestinal Tract

• Gastritis: Inflammation of the stomach.
• Gastroenteritis: Inflammation of the stomach and intestines.
• Enterocolitis: Inflammation of the small and large intestines.

Terms Related to Diarrhea

• Diarrhea: An abnormal increase in the frequency of bowel movements, resulting in loose or liquid stools.
• Dysentery: Diarrhea accompanied by cramping abdominal pain.
• Proctitis: Inflammation of the rectal mucosa. Common causes include N. gonorrhoeae, C. trachomatis, and T. pallidum.

Normal Flora of the Gastrointestinal Tract

• The normal flora in feces comprises 80% bacteria by dry weight.
• Normal flora prevents pathogens from colonizing the body.
• Common types of bacteria include anaerobic bacilli (e.g., Bacteroides spp.), Gram-negative enteric bacilli, enterococci, streptococci, Staphylococcus aureus, and yeast (Candida).

Non-Inflammatory Diarrhea

• Non-inflammatory diarrhea is caused by bacterial toxins or enterotoxins.
• It results in the outpouring of electrolytes and fluid, or watery stools.
• Patients with non-inflammatory diarrhea are afebrile, and their stools are watery, of large volume, and lack white blood cells (PMNs), blood, and mucus.
• Common causes include Vibrio cholerae, enterotoxigenic E. coli, Bacteroides spp., viruses (Giardia lamblia, Cyclospora, Cryptosporidium).

Inflammatory Diarrhea

• In inflammatory diarrhea, organisms invade the intestinal mucosa, and cytotoxins destroy intestinal cells.
• Patients with inflammatory diarrhea have fever, loose stools, and small stool volume.
• Their fecal specimens typically contain white blood cells (PMNs), blood, and mucus.
• Common causes include Salmonella spp., Shigella spp., Yersinia enterocolitica, Campylobacter spp., enteroinvasive E. coli, Clostridium difficile.

Enterotoxin-Mediated Diarrhea

• Enterotoxin-mediated diarrhea involves ingesting food containing toxins.
• Symptoms often appear rapidly, within 12 hours.
• Common causes include enterotoxigenic E. coli, Vibrio cholerae, Staphylococcus aureus, Clostridium perfringens, and Bacillus cereus.

Gastrointestinal Diseases

• Diarrheal diseases include:
  • Salmonella (gastroenteritis)
  • Shigella (bacillary dysentery)
  • Yersinia enterocolitica (enterocolitis)
  • Campylobacter jejuni and C. coli (resembling acute appendicitis)
• Other diarrheal diseases include: Edwardsiella tarda, Vibrio cholerae, V. parahaemolyticus, Plesiomonas shigelloides, Listeria monocytogenes.
• Intestinal parasites such as Giardia, Entamoeba, Cryptosporidium, Cyclospora, Microsporidia.
• Viruses (rotavirus, adenovirus, calcivirus, astrovirus).

Diseases (Gastrointestinal)

• H. pylori: causes chronic gastritis and peptic/duodenal ulcers.
• C. difficile: causes antibiotic-associated diarrhea and pseudomembranous colitis.
• C. perfringens: causes enterotoxin.
• Mycobacterium avium: causes GI diseases in AIDS patients.
• E. coli (enterohemorrhagic): causes hemorrhagic colitis and hemolytic uremic syndrome (HUS); common strains include E. coli O157:H7.
• E. coli (enteroinvasive): causes Shigella-like disease.
• E. coli (enterotoxigenic): causes traveler's diarrhea.
• E. coli (enteropathogenic): causes diarrhea, common in children
• E. coli (enteroaggregative): causes traveler's diarrhea

Transmission Routes of Gastrointestinal Infections

• Most gastrointestinal infections are transmitted via the fecal-oral route.
• Organisms or their toxins, ingested from contaminated water or food (e.g., Salmonella, S. aureus).
• Direct person-to-person contact (Shigella).
• Animal contact (e.g., Yersinia enterocolitica).
• Need to survive the low pH of the stomach.

Symptoms (Gastrointestinal)

• Common symptoms include nausea, vomiting, abdominal discomfort, and diarrhea.

Specimen Collection (Gastrointestinal)

• Fecal specimens should be collected in clean, non-sterile, wide-mouth containers.
• Avoid contamination with urine.
• Use transport media (e.g., Cary-Blair medium) to preserve specimens.
• Process specimens within 1-2 hours of collection.
• Other specimens: duodenal, colostomy, and ileostomy material, diapers, and food (for public health investigations).

Visual Examination (Gastrointestinal)

• A macroscopic examination of the stool includes observation of blood, mucus, consistency (watery, formed, loose), and color.

Microscopic Examination (Gastrointestinal)

• A microscopic examination of fecal specimens to examine for white blood cells (PMNs).
• This helps distinguish inflammatory from non-inflammatory conditions.
• Using methylene blue staining, for motility and morphology determination of Campylobacter
• Gram staining and morphology for Campylobacter, curved Gram-negative rods (Vibrio), Gram-positive rods (Clostridium).

Culture (Gastrointestinal)

• Culture often involves isolating Salmonella, Shigella, Campylobacter, E. coli O157:H7, and Vibrio.
• Rely on patient history and symptoms to select appropriate cultures.

Media (Gastrointestinal)

• BAP: detects Staphylococcus aureus and yeast.
• MAC/EMB: differential and selective media.
• NLF: selective for Salmonella, Shigella, Yersinia enterocolitica.
• XLD/HE/SS: differential and selective for Salmonella and Shigella.
• Campy-BAP: selective for Campylobacter.
• Enrichment broth: Used to cultivate Salmonella, Shigella, etc; Salmonella, Shigella.
• Selenite F: used to cultivate Salmonella, some Shigella.
• CIN: selective for Yersinia enterocolitica.
• SS: selective for Salmonella and Shigella.
• Sorbitol MAC: for distinguishing E. coli from E. coli O157:H7.
• TCBS: selective for Vibrio.
• CCFA: selective for Clostridium difficile.

Incubation Conditions (Gastrointestinal)

• Most cultures incubated between 35-37 degrees C in ambient conditions.
• Campylobacter require microaerobic conditions at 42C
• Enrichment media cultured for a few hours and subsequently subcultured onto solid media.

Work-up (Gastrointestinal)

• Examine cultures for organisms suspected of causing infection.
• Use biochemical tests to help identify pathogenic bacteria earlier in the diagnosis process.

Reporting Results (Gastrointestinal)

• Results from identification and susceptibility testing are reported; public health authorities are notified of any pathogenic bacteria isolates (e.g., Salmonella, Shigella).
• The report may specify overgrowth of S. aureus, yeast, or other organisms.
• Negative results indicate no presence of the specified organisms (e.g., no Salmonella, Shigella, Vibrio, E. coli O157:H7, or Campylobacter).

Respiratory Tract Study Notes

• Upper Respiratory Tract (URT): Includes the oral cavity, nose, mouth, throat, epiglottis, and larynx.
• Lower Respiratory Tract (LRT): Includes the trachea, bronchi, bronchioles, and lung alveoli.
• The area below the larynx is normally sterile.
• The URT contains normal flora.
• Urt infections commonly involve nose, mouth, throat, epiglottis, larynx

Normal Flora of the URT

• Staphylococcus (Staphylococci, S. aureus, CONS)
• Streptococci (viridans, pneumococci)
• Micrococcus spp.
• Diphtheroids (organisms resembling Corynebacterium)
• Neisseria spp.
• Haemophilus spp.
• Anaerobes
• Spirochetes
• Candida spp.

URT Infections

• Pneumonia
• Whooping cough (Pertussis)
• Diphtheria
• Epiglottitis
• Sinusitis
• Tonsillitis
• Laryngitis
• Pharyngitis
• Thrush
• Otitis media

Pathogens (URT)

• Respiratory viruses (influenza, parainfluenza, RSV, adenovirus, rhinovirus, coronavirus, coxsackie A, EBV, CMV)
• S. pyogenes
• B-hemolytic strep groups C, F, and G
• Arcanobacterium haemolyticum
• H. influenzae, parainfluenzae
• N. gonorrhoeae
• Corynebacterium diphtheriae
• Bordetella pertussis, parapertussis
• Yeast

Specimen Collection (URT)

• Throat cultures: posterior pharynx and tonsils are swabbed; placed in transport media
• Biopsies: tissue samples from affected areas.
• Syringe and needle used to collect specimens.

Microscopic Examination (URT)

• Gram stain: Is not usually a diagnostic tool, and shows high quantities of normal flora.
• Throat cultures: used for identifying the causative organisms, looking for group A strep

Culture (URT)

• Throat cultures: mainly for group A strep.

Pneumonia (Community-acquired and Hospital-acquired)

• Community-acquired: commonly caused by Streptococcus pneumoniae, Mycoplasma pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis.
• Hospital-acquired: often caused by Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, Enterobacteriaceae, and anaerobic bacteria.

Miscellaneous Causative Agents (URT/LRT)

• Mycobacteria (e.g., tuberculosis).
• Legionella.
• Chlamydia (e.g., C. trachomatis, C. pneumoniae).
• Emerging viral infections (e.g., avian influenza, H1N1 influenza).
• Bioterrorism agents (e.g., Bacillus anthracis, Yersinia pestis, Coxiella burnetii, Francisella tularensis).

Routes of Infection (LRT)

• Most infections are opportunistic. Defense mechanisms are compromised or weakened allowing pathogens to infect the lungs.
• Inhalation of infectious aerosols.
• Hematogenous (blood stream) transmission
• Aspiration of oral secretions or gastric contents. (excessive drinking, intubation)
• Sputum is the easiest specimen to collect, but cultures are challenging because of normal flora.

Specimen Collection (LRT)

• Sputum (non-invasive): Expectorated sputum, deep cough samples, assisted by respiratory therapists using chest percussions, aerosol saline to induce coughing.
• Sputum (invasive): Bronchoscopy, bronchial lavage or washings, bronchial biopsy, endotracheal aspirates, tracheostomy aspirates.
• Fluid aspirates: Tympanocentesis (Middle Ear) aspirate
• Other specimen types : Pleural fluid

Processing Specimens (LRT)

• Sputum processing: Gram stain to determine if there are pathogenic organisms. Cultures performed using BAP, CHOC, MAC agar; incubated in CO2, in 35 degree C. For cystic fibrosis, special media for B. cepacia, MRSA, and Pseudomonas used.
• Anaerobic respiratory cultures: done for pleural fluids, and lung biopsies; specimens that bypasses the oral cavity should be cultured.
• Specimen processing (otitis): gram stain, then culture.

Test your knowledge on gastrointestinal disorders with this quiz. It covers key concepts such as inflammation, diarrhea types, and the role of normal flora. Perfect for students studying anatomy or medicine.