MICRO Flashcards
H pylori is associated with what longterm complications?
Chronic gastritis
Adenocarcinoma
MALTomas
What are the VFs for H pylori?
Vac A-> vaculating cytotoxin
PAI-> encodes Type III secreting system
Cag-> rearranges cytoskeleton
Urease
Which of the H pylori VFs causes gastritis and adenocarcinoma?
Urease-> gastritis
Cag- Carcinoma
What are the diagnostic tests for H pylori?
Biopsy-> culture
Urea breath test
Serology= Good for treatment and recovery
Most common bacterial GI infection in developed countries, caused by Uncooked Poultry and unpasteurized milk?
Campylobacter jejuni
Spiral shaped G- rod, that causes fever, **Appendicitis like lower abdominal pain,
Watery diarrhea progresses to Bloody/Pus diarrhea?
Campylobacter jejuni
What is the sequelae for C jejuni infection (Pg)?
X-reactive antibodies to Cj lipooligosaccharides cross react with Myelin= Guillain- Barre
Curved G- Rod
Oxidase +
Motile
Found in saltwater?
Vibrio (cholera)
Infection associated with poor sanitation, contaminated water/food, >200 serogroups based on O-antigen (O1 & O139 responsible for pandemics)?
Vibrio cholera
2-3 days post infection, abrupt onset of Vomiting, HIgh volume Watery diarrhea, eventual death by Dehydration?
V cholera–> cholera toxin activates Adenylyl cyclase
High volume “Rice water stools?”
V cholera
What are the VFs for cholera?
PAI-> encoded pilus for attachment
Phage encoded toxin
Toxin causes ADP ribosylation of GTP-binding protein and activates adenylyl cyclase causing Secretory diarrhea. What is the Dx tests for the organism?
Cholera toxin-> Culture on TCBS (thiosulfate citrate bile salts sucrose) or MacConkey agars
What are the culture medians used to diagnose cholera?
TCBS
MacConkey agars
Found in sea-water and SEAFOOD poisoning, MC food born illness in Japan, causing watery diarrhea, Cramps, N/V, **24hrs after exposure?
Vibrio parahaemolyticus
Found in sea water, infection through RAW Oysters, causes Cellulitis, vomiting, diarrhea, Bullae and septicemia in Immunocomprimised patients?
V vulnificus (BULLAE)
**highly fatal (20%)
What are the characteristics of Anaerobic infections/bacteria?
Lack SOD and Catalase negative
STINKY PUS
Smelly breath
Abscess + tissue necrosis
Pt with foul smelling breath and GI infection. What is the most likely characteristic of the infection?
Caused by Anaerobic bacteria
G- coccobacillus with Anti-phagocytic capsule, most common anaerobic infection causing abscesses, PID, and pulmonary infections?
Bacteriodes fragilis
**PID + GI
G- coccobacillus + anti-phagocytic capsule
Opportunistic abscess, pulmonary and Periodontal infections?
Prevotella melaninogenica
**Periodontal + GI
G+ anaerobic spore forming Rods
resistant to high heat + harsh environments
Exotoxins and secrete Hydrolytic enzymes?
Clostridium
**ONLY anaerobic spore forming Rod
Large Boxcar G+ Rods
Found in soil and intestines
Cause GAS GANGRENE + cellulitis + food poisoning?
Clostridium perfringens
Contamination of wounds by spores causes necrosis and gas formation?
C perfringes Gas gangrene
Enterotoxins found in Meats at low temp allowing spores to germinate, causes Nausea, diarrhea, pain, NO Fever or Vomiting within 8-24hrs?
C perfringens food poisoning
AB neurotoxin entering Neuromuscular junction and transported by motor neurons to ganglia, Cuts V-snare?
C tetani (tetanus toxin)
What is the action of Tetanus toxin?
Cuts V-snare
Vesicles and Neurotransmitters cant fuse with membrane
Prevents Release of Inhibitory NT (GABA and glycine)
What bacterial toxin inhibits the blocking of postsynaptic inhibition of spinal motor reflexes (GABA)?
Tetanus toxin
What are the signs and symptoms of Tetanus infection?
TRISMUS (Lock Jaw)
Risus sardonicus= facial spasma causing a GRIN
Spasms
Death via exhaustion and Respiratory failure
What is the treatment for tetanus poisoning?
HTIG to soak up the excess toxin
Sedate to avoid exhaustion and allow for new axon generation
Trismus + V-snare?
Tetanus toxin
Most toxic bacterial exotoxin
Cleave V and T snare
Prevents ACh release?
Botulinum toxin
Bacterial spores are resistant to heat and germinate after cooking, toxins are heat labile, but infection causes ACUTE symmetric descending Flaccid Paralysis?
Botulism
Pt with symptoms 12-36hrs post infections from food contaminated with spores, presents with Nausea Dry mouth Diarrhea Blurred vision Respiratory failure?
Botulism = Inhibits ACh release
“Floopy baby” syndrome, infants 3wks-8mo, causing constipation, poor muscle tone, and feeding problems?
infant Botulism
Most common nosocomial infection causing diarrhea post-antibiotic therapy?
C difficile
What are the actions of C difficile Toxins A and B?
A (enterotoxin)= Diarrhea
B (Cytotoxin)= Inflammation
bacterial infection if hospitalized pt causing Fever, Watery diarrhea -> bloody
and presences of pseudomembranous colitis. What are the diagnostic tests and treatment for this infection?
Dx: Tox B from stool culture
RADT fro Tox A & B in stool
Rx; Discontinue antibiotics
Causes Persistant Gi infection?
H pylori
Food borne infection + Watery to bloody diarrhea?
C jejuni
Watery diarrhea + Food borne + seasonal?
V cholera
V parahaemolyticus
Normal flora + Nosocomial infections?
B fragilis
Normal flora + watery diarrhea?
C perfringes
Flaccid paralysis ?
Botulism
Watery diarrhea + Normal flora + nosocomial infections?
C difficile
What organisms can cause watery diarrhea?
V cholera + parahaemolyticus
C perfringens
C difficile
Can cause Watery–> Bloody diarrhea?
C jejuni
Food borne GI infections?
C jejuni
Vibrio
C perfringens
Opportunistic infections caused by normal flora?
B fragilis
C difficile
G- facultative anaerobe Ferments glucose Oxidase negative Nitrates--> Nitrites Motile by peritrichous flagella?
Enterobacteriaceae
What is a MacConkey agar?
Selective and differential media
Contains chemicals that inhibit G+ organisms
pH indicator= red->yellow when <6.8
Lactose fermentators can cause color change(Ecoli)
80-90% of diarrheas in USA are caused by?
VIRUSES
Describe non-inflammatory diarrhea?
Watery + HIGH volume
Due to ENTEROTOXIN acting on Ion channels
NO fever
NO fecal leukocytes
Describe Inflammatory or invasive diarrhea?
LOW volume Cytotoxin induced Feces + for Methylene blue and lactoferrin (WBC) FEVER Dysentery BLOOD + Mucus in Feces TENESMUS= painful spasms of anal sphincter >2wks= parasite
What agents usually cause diarrhea in AIDS patients?
Cryptosporidium
Mycobacterium avium
CMV
What tests are performed to identify the causative agent of diarrhea?
Culture
Rapid Ag Detection Tests (RADTs) for viruses/toxin
Microscopic exam for parasites
What is contraindicated in patients with Enterohemorrhagic E coli Dysentery?
Antibiotic treatment
What is the complication of EHEC induced diarrhea?
HUS
What is the complication of C jejuni induced diarrhea?
Guillian Barre
What organisms are associated with Reiter’s syndrome (polyarthritis + conjunctivitis + urethritis) as complications of diarrhea?
Shigella
Campylobacter
Yersinia
Salmonella
Lac +
Femrents Glucose with H2
Does NOT produce H2S
Motile?
E coli
- *salmonella= H2S +
- *Shigella= H2S - & NO gas (H2)
What strain of E coli causes Hemorrhagic colitis with Sudden onset of Severe abdominal cramps and Watery diarrhea that is Bloody within 24hrs?
Enterohemorrhagic E coli (EHEC)
**O157:H7
4 yo child with Bloody diarrhea for 1-8 days
NO Fever and absent leukocytes
Anemia and Thrombocytopenia. What is the most likely complication?
HUS–> acute kidney failure
**MCC of pediatric acute renal failure
What symptoms are complications are associated with E coli O157:H7?
HUS–> acute renal failure
- *Seizures + Strokes
- *Anemia + Thrombocytopenia
Child with Anemia, Thrombocytopenia, and uremia, possibly seizures?
HUS–> EHEC infection
Reservoir is cattle but does not cause infections in cattle, Major source of human infection is GROUND BEEF, unpasteurized milk, and juice, lettuce, or salami. Can also spread in child care centers?
EHEC **Recent outbreaks associated with: Spinach Unpasteurized juice Alfalfa sprouts
What are the VFs for EHEC (O157:H7)?
Enterotoxin= Shiga-like Toxins
**Inhibits protein synthesis and results in cell death–> disseminates to Kidneys
Pathogenicity island= Type3 secretion system
LEE PAI= Causes diarrhea
What are the diagnostic tests for EHEC (O157:H7)?
Sorbitol MacConkey agar
**O157:H7 is Sorbitol negative but Normal Ecoli is Sorbitol +
RADT for Shiga Toxins in stool
What organism is the leading cause of bacterial diarrhea and TRAVELERS diarrhea?
ETEC (enterotoxigenic E coli)
**contain enterotoxins and fimbriae
What type of E coli cannot ferment Sorbitol?
EHEC O157:H7
Causes noninflammatory HIGH volume diarrhea similar to cholera. Contains 2 VFs: LT and ST?
ETEC
- *LT= heat labile= Acts just like Cholera toxin
- *ST= heat stable= increases cGMP-> cAMP
What G- rod organism has a AB toxin that binds ganglioside receptors and enzymatically activates adenylyl cyclase leading to Chloride efflux?
ETEC= LT TOXIN
**Cholera Like toxin
WHat is the function of ST toxin of ETEC?
Binds Guanylyl cyclase receptor= activates PKA
Increased cAMP = activation of CFTR
Diarrhea
What type of E coli resembles Cholera and Shigella?
Cholera= ETEC Shigella= EIEC
E coli serotype that causes Dysentery-like diarrhea and fever. organism lacks fimbrial adhesions and does not produce LT or ST toxins, NON motile and LAC-?
EIEC
E coli strain with: Fimbrial adhesions (CFA1&2) LT & ST toxins Watery diarrhea in infants/travelers= NO fever High infectious dose?
ETEC
E coli strain with: Nonfimbrial adhesins penetrates and multiply in epithelial cells NO Shiga Toxin Dysentery like Diarrhea + FEVER?
EIEC
E coli strain with:
Intimin adhesin proteins
EAF binds to intestinal cells
Infantile diarrhea?
EPEC
E coli strain with:
NO characterized adhesins
ST like toxin and Hemolysin
Persistant diarrhea in Young children?
EAEC
E coli strain with: Fimbrial adhesin Phage coded Shiga toxin Copious bloody diarrhea + intense inflammation MCC of hemorrhagic colitis in US LOW INFECTIOUS DOSE?
EHEC = causes HUS
What is the function of K antigen in UPEC?
Polysaccharide capsule protects against Phagocytosis by PMNs + Ab and complement deposition
K-1= antiphagocytic and antigenic disguise
What is the major E coli VF that causes neonatal Meningitis?
K-1 antigen = Homopolymer of sialic acid
Lac-
Ferments Glucose + H2 gas formation
H2S + ?
Salmonella
**only difference with E coli is Lac (+)