Gastrointestinal Disorders Quiz

Gastrointestinal Tract

The gastrointestinal tract (GI tract) includes the esophagus, stomach, small intestines (duodenum, jejunum, ileum), large intestines (cecum, colon, rectum), and anus.
The GI tract is responsible for the breakdown and absorption of food.
Inflammation of the stomach is called gastritis.
Inflammation of the stomach and intestines is called gastroenteritis.
Inflammation of the small and large intestines is called enterocolitis.
Diarrhea is an abnormal increase in bowel movements, which can range from loose to liquid stool.
Dysentery is diarrhea with cramping abdominal pain.
Proctitis is the inflammation of the rectal mucosa.
80% of the dry weight of feces is bacteria (normal flora).
Normal flora prevents colonization of pathogens.
Common bacteria includes anaerobic bacillus, GN enteric bacillus, enterococci, streptococci, S. aureus, and yeast (Candida).
Non-inflammatory diarrhea is caused by bacterial toxins or enterotoxins, resulting in watery stool and fluid loss, but no fever and no inflammatory cells in the stool.
Common causes of non-inflammatory diarrhea include bacterial toxins from V. cholerae, Enterotoxigenic E. coli, and other Bacteroides species. The causes may also be viruses like Giardia lamblia, Cyclospora, or Cryptosporidium.
Inflammatory diarrhea is caused by organisms invading the intestinal mucosa, producing cytotoxins that destroy the intestinal cells.
Patients with inflammatory diarrhea typically have fever and loose, small-volume stool with white blood cells present in the stool, blood, and mucous.
Common causative agents for inflammatory diarrhea include Salmonella, Shigella, Y. enterocolitica, Campylobacter, Enteroinvasive E. coli, and Clostridium difficile.
Enterotoxin-mediated diarrhea is caused by ingesting food containing enterotoxins. These toxins lead to rapid onset of diarrhea (less than 12 hours).
Common causes of enterotoxin-mediated diarrhea include Enterotoxigenic E. coli, V. cholera, S. aureus, C. perfringens, and B. cereus.
Diarrheal diseases include Salmonella (gastroenteritis), Shigella (bacillary dysentery), Y. enterocolitica(enterocolitis), Campylobacter jejuni and C. coli, Edwardsiella tarda (uncommon), Vibrio cholerae (cholera), V. parahaemolyticus (milder case), Plesiomonas shigelloides, and Listeria monocytogenes (gastroenteritis).
Intestinal parasites can cause diarrhea, including Giardia, Entamoeba, Cryptosporidium, Cyclospora, and Microsporidia.
Other diseases include diseases caused H. pylori (chronic gastritis), C. difficile (antibiotic-associated diarrhea), C. perfringens (enterotoxin), Mycobacterium avium (GI diseases in AIDS patients or E. coli(hemorrhagic colitis and hemolytic uremic syndrome (HUS).
Specific types of E. coli may cause diarrhea (enterohemorrhagic, enteroinvasive, enterotoxigenic, enteropathogenic, enteroaggregative).
Transmission routes include fecal-oral, direct person-to-person, animal contact, or survival of gastric pH.
Symptoms of gastrointestinal infections include nausea, vomiting, abdominal discomfort, and diarrhea.
Stool specimen collection should consist of 2-3 samples of fecal matter in a clean, non-sterile wide-open container. The specimen should not be contaminated by urine. Cary-Blair transport media are recommended to retain organisms during transport. The specimen should be processed within 1-2 hours of collection.
Other specimens such as duodenal, colostomy, ileostomy material, diapers, and food products (public health labs/outbreaks).
Visual examination would involve macroscopic examination of blood, mucous, stool consistency (watery, formed, loose), and color.
Microscopic examination would involve fecal white blood cells (PMNs), use of methylene blue, motility of Campylobacter, gram stain and morphology, curved GNR (Vibrio), and GPR (Clostridium).
Stool white blood cells (WBCs) distinguish inflammatory from non-inflammatory diarrhea.
Culture of suspected organisms would depend on patient history/symptoms, as large numbers of organisms require careful processing and testing to focus on suspected organisms. Non-routine cultures will require contacting a healthcare facility for testing.
Culture media include BAP, MAC, EMB, XLD, HE, SS, TCBS, Campy-BAP, and special media for Y. enterocolitica, Salmonella, Shigella, E. coli, Vibrio, Plesiomonas, Aeromonas among others.
Incubation conditions depend on the organism, using ambient air at 35°C, or microaerobic conditions at 42°C.
Result reporting includes identification and susceptibility testing panels, notification for public health when Salmonella or Shigella is isolated, and report any organism overgrowths like S. aureus, yeast, and Pseudomonas.

Respiratory Tract

The upper respiratory tract (URT) includes the oral cavity, nose, mouth, throat, epiglottis, and larynx. The normal flora (NF) in this area includes Staphylococci, CONS, S. aureus, Streptococci, viridans, pneumococci, Micrococcus spp., Diphtheroids, Neisseria spp., Haemophilus, Anaerobes, and Spirochetes, all of which can cause infections.
The lower respiratory tract (LRT) includes the trachea, bronchi, bronchioles, lung alveoli; this section is normally sterile.
URT infections include thrush, laryngitis, epiglottitis, pharyngitis, tonsillitis, sinusitis, otitis media, and diphtheria.
LRT infections include bronchitis, influenza, pneumonia, empyema (purulent fluid in the pleural space), and tuberculosis.
URT causative agents for infections include Respiratory viruses (influenza, parainfluenza, RSV, adenovirus, rhinovirus, coronavirus, coxsackie A, EBV, CMV), S. pyogenes, B-hemolytic strep group (C, F, G), and Arcanobacterium haemolyticum.
Other possible pathogens include H. influenzae, N. gonorrhoeae, Corynebacterium diphtheriae, Bordetella pertussis, and parapertussis yeast species.
Specimen collection for URT can include swabs, syringes and needles, biopsies.
Specimen collection for URT should mainly test for group A strep initially, testing for group B, C, F, & G, N. gonorrhoeae, and C. diphtheriae.
Throat cultures and cultures using BAP, CHOC, & MAC will require incubating in CO2.
Samples such as sputum, tracheal aspirates, bronchial washings, bronchial brushings, and bronchial biopsies can be tested, along with anaerobic Cultures(pleural fluid) or open-lung biopsies.
Gram stain helps determine the presence of epithelial cells (or if sputum is suitable for culture), and quantities.
Respiratory viruses like influenza A and avian influenza H5N1, H1N1 influenza A, and severe acute respiratory syndrome (SARS) can cause further issues.
Other pathogens for LRT infections include gram-negative rods (GNR), S. aureus, legionella, anaerobes, mycobacteria, and fungi.
Community-acquired pneumonia agents include S. pneumoniae, mycoplasma pneumoniae, H. influenza, M. catarrhalis, also S. aureus, etc.
Hospital-acquired pneumonia agents include Enterobacteriaceae, K. pneumoniae, S. marcescens, S. aureus, NFGNR, P. aeruginosa, Burkholderia cepacia, CF and nosocomial S. pneumoniae, and anaerobic bacteria.
Additional miscellaneous agents include Mycobacteria, Legionella (immunocompromised individuals), Chlamydia group (neonates and young adults), and bioterrorism threats like B. anthracis, Y. pestis, Coxiella burnetii, and F. tularensis.
Specimens and methods for collection, handling or processing and types of cultures or media available depend on the suspected agent or location.