Week 2 GI & ENT Flashcards
What are the common GIT infections?
- Bacterial gastroenteritis
- Viral/Parasitic gastroenteritis
- Amoebiasis
- Giardiasis
- Toxic megacolon
What are the common intra-abdominal infections?
- Peritonitis
- Cholecytitis
- Diverticulitis
- Intra-abdominal, liver or pancreatic abscess
- Peptic ulcer disease
What are the common ENT infections? (10)
- Pharyngitis
- Diphtheria
- Epiglottitis
- Otitis externa
- Otitis media
- Mastoiditis
- Sinusitis
- Conjunctivitis
- Keratitis
- Endophthalmitis
What are the common organisms causing bacterial GE?
- Salmonella spp (mostly S enteriditis, S typhi & S paratyphi)
- Shigella spp
- Campylobacter jejuni
- Vibrio spp
- Clostridium difficile
How are the common Salmonella spp transmitted and what GI infection do they cause?
Causes bacterial GE
Salmonella enteriditis
- Most common
- Transmitted through food
- Usually self-limiting
Salmonella typhi (typhoid fever) & Salmonella paratyphi
- Causes more dangerous manifestations
- P.t. transmitted by water
- P.p transmitted from person-to-person (eg ingestion of fecal-contaminated food/water)
- Must be treated with antibiotics
- Not endemic in Singapore
How is shigella spp transmitted and what GI infection does it normally cause?
- Can cause bacterial GE
- Transmitted from person-to-person
- Disease is usually self-limiting
How is Campylobacter jejuni transmitted and what GI infection does it normally cause?
- Can cause bacterial GE
- Transmitted through food (mostly chicken)
- Usually self-limiting
How is Vibrio spp transmitted and what GI infection does it normally cause?
- Can cause bacterial GE
- Transmitted through raw seafood
- Usually self-limiting
Note: Vibrio cholera
- Causes the most serious effects, and can cause death
- Transmitted through water
- Common indicator is “rice water stool”
How is Clostridium difficile transmitted and what GI infection does it normally cause?
- Can cause bacterial GE
- Starts off with antibiotic exposure and then transmitted person-to-person
- Especially common in hospital environments
- Treatment involves stopping the current antibiotic and replacing it with one that targets the GI
- Dangerous as it can lead to colitis, toxic megacolon or death
What is haemolytic uraemic syndrome?
- Serious condition affecting the kidneys
- Caused by EHEC/E.coli strain 0157
- Transmitted through contaminated food or water
What samples and tests do you send for to test for Salmonella spp, Shigella spp, Vibrio spp and Campylobacter causing bacterial GE?
- Stool sample
- Culture and sensitivity test
- TAT 24-48 hours
What samples and tests do you send to test for C. difficile causing bacterial GE?
- Stool
- C. diff toxin test
- C&S not done as C. diff is hard to grow
What are the common viruses that cause viral GE?
- Norovirus
- Rotavirus
- Adenovirus
note: all these viruses are common in children and in nurseries
How is Norovirus transmitted and what GI infection can it cause?
- Viral GE
- Can lead to uncontrolled diarrhea and vomiting (easily spread in hospitals)
- Transmitted through contaminated food/shellfish/water and fecal-contaminated sources
- Usually self-limiting
How are Rotavirus and Adenovirus transmitted and what GI infection can it cause?
- Viral GE
- Commonly causes paediatric diarrhea
- Transmitted person-to-person
- Usually self-limiting
What samples and tests do you send to test for rotavirus, adenovirus and norovirus causing viral GE?
- Stool sample
- Enzyme immunoassay (EIA) test and/or
- Polymerase chain reaction (PCR) test
- C&S not done as viral cultures takes too long to grow
Cause and diagnosis of Amoebiasis?
- By Entamoeba histolytica parasite
Diagnosis through
- Microscopy of stool specimens (to visualise parasite)
- Blood serology if systemic infection is suspected
Systemic infection
- More dangerous
- Usually abscess in the liver
- Pus will look like anchovy sauce
Cause and diagnosis of giardiasis?
- Giardia parasite (G. intestanalis, lambia, duodenalis)
- Diagnosis through stool microscopy
Cause and diagnosis of toxic megacolon?
- Microbe cause: C. difficile
- PP cause: Inflammatory bowel disease, ischemic colitis, medicinal drugs, other inflammatory conditions
- Common in elderly due to use of many antibiotics
Impending signs:
- Distended abdomen but no diarrhea/output
- Antibiotics alone is not enough to treat
Brief on the other intra-abdominal infections and what microbes can cause them?
- Cholecystitis (infl of gallbladder) leading to cholangitis (infl of bile duct)
- Diverticulitis (infl of intestines)
- Abscesses
Caused by:
- Coliforms (eg E. coli, Klebsiella, Enterobacter)
- Anaerobes
- Enterococci
- P. aeruginosa
- Candida
What is the pathophysiology of peritonitis?
- Usually due to the perforation of intestines, gallbladder or other organs within the abdomen and spills over into the sterile peritoneum
- May also be due to C. diff toxins
Primary:
- Liver disease -> ascites -> spontaneous bacterial peritonitis
Secondary:
- Associated with peritoneal dialysis
What pathogens can cause peritonitis?
Primary:
- Coliforms
- Pseudomonas aeruginosa
- Anaerobes
- Enterococci
- Candida
Secondary:
- Primary +
- Coagulase-negative Staphylococcus (Skin flora)
- Staph aureus
- Other environmental bacteria (due to foreign object)
Cause and pathophysiology of peptic ulcer disease?
- Helicobacter pylori
- Bacteria can survive due to urease production (neutralises stomach acid)
- Chronic condition may lead to stomach cancer
- Gastric biopsy may be needed if repeated courses of Abx does not work
What is the most common first line of antibiotics?
Ceftriaxone
Why should frequent use of Ciproflaxin be discouraged?
- One of the few Abx that can be used to treat UTI caused by Pseudomonas aeruginosa
- If px is resistant to Ciproflaxin, IV Abx needs to be started
What are the common pathogens causing Pharyngitis? (IMPT)
1) Viruses
- Most common
- eg Rhinovirus, Adenovirus, Parainfluenza, EBV
- Disease is usually self-limiting
2) Group A Streptococcus
- especially Streptococcus pyogenes
- necessary to treat with antibiotics to prevent complications, can give Abx prophylaxis also
- eg rheumatic fever/heart disease, glomerulonephritis, tonsillar abscess
3) Corynebacterium diphtheria
- Fatal due to airway obstruction and/or arrhythmia from exotoxins
- Common in countries w poor vaccination rates
4) Neisseria gonorrhea
5) Fusobacterium necrophorum
What are the causes of Diphtheria and their signs?
- Corynebacterium diphtheriae
- Transmitted through infected droplets or surfaces
- Incubated for 2-5 days and infectious until at least 14 days of Abx therapy
- s/s include “bull/thick” neck appearance, thick pseudomembrane in the tonsils, sore throat, fever
- Arrythmias, myocarditis and heart blocks can occur if toxins are involved
- Toxigenic strains also cause the pseudomembranes and nerve toxicity
- Non-toxigenic strains merely colonise the airway
What is the diagnosis, treatment and prevention of Diphtheria?
Diagnosis:
- Culture from nasopharyngeal swab
Treatment:
- Abx (Erythromycin, Penicillin)
- Antitoxin
Prevention:
- Vaccination
- Abx prophylaxis
Epiglottitis?
- Haemophilus influenzae type B
- Infected epiglottis
- s/s drooling, difficulty swallowing, airway obstruction and difficulty breathing
- Do not take throat swab
Normal Otitis externa? (OE)
- Staph aureus and Pseudomonas aeruginosa
- Infected external auditory canal
- Due to water trapped in ear, or heavy use of hearing aids/ear phones
- Treatment with antibiotic ear drops
Malignant Otitis externa
- Mostly due to pseudomonas aeruginosa
- Seen in diabetics or immunocompromised
- More serious as infection may invade the bone, blood vessels and nerves
- Treatment is for at least 6 weeks and IV Abx
Otitis media? (OM)
- Usually viral but
- Common bacteria include Streptococcus pneumoniae and Haemophilus influenza
- Obstruction of eustachian tube
- Treat with antibiotics is due to bacteria
- Complication may include mastoiditis leading to brain abscess
Mastoiditis?
Mastoiditis is an infection of your mastoid bone, the large bone behind your ear.
What pathogens commonly cause Sinusitis?
- Streptococcus pneumoniae
- Haemophilus influenzae
Causes and s/s of Conjunctivitis? (IMPT)
- Mostly viral:
~ Adenovirus
~ Enterovirus - Bacteria:
~ Staph aureus
~ Strep pneumoniae
~ Pseudomonas aeruginosa (contact lens) - s/s:
~ Thick purulent exudate if bacterial in origins
~ Red eyes
~ Usually in children
Causes and s/s of Keratitis?
- Mostly bacterial
~ Similar to conjunctivitis
~ coliforms
~ Group A Strep
s/s:
- May lead to blindness
- Not so much discharge, more watery eyes
Causes of Endophthalmitis?
- Staph aureus
- Streptococcus
- Candida
