Term
| Vibrio cholera: Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory)
Bacterial Enterotoxigenic |
|
|
Term
| Vibrio cholera: Virulence Factors |
|
Definition
Adherence: most important
-Pili (Tcp)
-Other adhesins
Motility: flagella
Cholera Toxin: AB type
-Secreted*
-Binds GM1 ganglioside on mucosal cells |
|
|
Term
| Vibrio cholera: Etiology/Pathogenesis |
|
Definition
Cholera Toxin: causes increase in cAMP resulting in water loss
IP: 2-3 days
Symptoms:
-Vomiting
-Massive, watery diarrhea (rice-water stool)
Rapid dehydration and electrolyte loss! |
|
|
Term
| Vibrio cholera: Transmission |
|
Definition
Fecal-oral: via contaminated water, fish and shellfish
Carriers: recovered patients can still shed organism
Large inoculums required: sensitive to gastric acids |
|
|
Term
| Vibrio cholera: Clinical ID |
|
Definition
By stool specimen only
Curved G (-)
Lab Tests:
-Oxidase (+)
Special Media:
-TCBS
O Antigens: O1 and O139 make cholera toxin |
|
|
Term
| Enterotoxogenic E. coli (ETEC): Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory)
Bacterial Enterotoxigenic |
|
|
Term
| Enterotoxogenic E. coli (ETEC): Virulence Factors |
|
Definition
Adherence:
-Adhesins
-Bundle-forming pilus (similar to Tcp)
Exotoxins:
Heat Labile Toxin (LT): similar to cholera toxin
-Same structure and MOA
-Binds same receptor (GM1 ganglioside)
-However, NOT SECRETED (localized to periplasm)
Heat Stable Toxin (ST):
-Family of small molecules
-Different MOA |
|
|
Term
| Enterotoxogenic E. coli (ETEC): Etiology/Pathogensis |
|
Definition
Traveler’s Diarrhea: most common cause (esp. in young children)
LT: increases cAMP resulting in fluid and electrolyte loss
ST: increases cGMP resulting in fluid and electrolyte loss
IP: 1-2 days
Symptoms:
-N/V
-Weakness/dizziness
-Abdominal pain
-Low grade fever
-Watery diarrhea |
|
|
Term
| Enterotoxogenic E. coli (ETEC): Transmission |
|
Definition
| Fecal-oral: contaminated food and beverages |
|
|
Term
| Enterotoxogenic E. coli (ETEC): Clinical ID |
|
Definition
G(-) rod
Lab Tests:
-Oxidase (-)
Test for presence of toxins:
-ELISA
-Agglutination test
-DNA probes for LT/ST genes |
|
|
Term
| Enteropathogenic E. coli (EPEC): Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory)
Bacterial Enterotoxin |
|
|
Term
| Enteropathogenic E. coli (EPEC): Virulence Factors |
|
Definition
Attaching/Effacing Lesion:
-Non-Int Binding: bundle forming pilus
-Int Binding: Tir and intimin
-Effacement: loss of microvilli, formation of pedestal structure under organism
Type III Secretion:
-Injects proteins directly into cell (Abs never see them)
-Can even inject a receptor for itself to facilitate binding |
|
|
Term
| Enteropathogenic E. coli (EPEC): Etiology/Pathogenesis |
|
Definition
Cause severe, often fatal, watery diarrhea: in infants and children in developing countries
*Dehydration and electrolyte balance can cause death*
May also cause Traveler’s diarrhea: in adults
Symptoms:
-Mucous, watery diarrhea
-Fever
-N/V
Malabsorptive Diarrhea: due to effacement |
|
|
Term
| Enteropathogenic E. coli (EPEC): Transmission |
|
Definition
| Fecal-oral: previously associated with outbreaks in nurseries |
|
|
Term
| Enteropathogenic E. coli (EPEC): Clinical ID |
|
Definition
G(-) rod
Lab Tests:
-Oxidase (-)
Detection:
-ELISA
-Multiplex PCR |
|
|
Term
| Clostridium botulinum: Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory) (although usually no diarrhea)
Bacterial Neurotoxin |
|
|
Term
| Clostridium botulinum: Virulence Factors |
|
Definition
Botulinal Toxin: AB toxin
-Usually ingested as a preformed toxin
-Binds ganglioside R on nerve cells
-Can be inactivated if boiled for 10-15 minutes |
|
|
Term
| Clostridium botulinum: Etiology/Pathogenesis |
|
Definition
Botulinal toxin: blocks presynaptic release of ACh at NMJ (flaccid paralysis)
Food botulism: ingestion of preformed toxin
-Absorbed in stomach and enters bloodstream
-Sx 12-36 hours later
Infant botulism: ingestion of spores
-Will grow and produce toxin
-Rare cause of SIDS
Wound botulism: spores colonize DEEP wounds (anaerobic)
-Will grow and produce toxin
No diarrhea associated!! |
|
|
Term
| Clostridium botulinum: Transmission |
|
Definition
Ingestion of spores: heat resistant and can be found in soil, animal feces, and lake sediment
Ingestion of preformed toxin: most notably in canned goods (anaerobic) |
|
|
Term
| Clostridium botulinum: Clinical ID |
|
Definition
G (+) rod
Spore forming
Anaerobic
Toxin Detection:
-Immunoassay (of food, gastric contents or blood) |
|
|
Term
| Staphylococcus aureus: Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory) (although usually no diarrhea)
Bacterial Neurotoxin |
|
|
Term
| Staphylococcus aureus: Virulence Factors |
|
Definition
Pre-Formed Enterotoxin:
-Absorbed in gut and stimulates neural R
-Stimulus sent to vomiting center in CNS
-Heat-stable |
|
|
Term
| Staphylococcus aureus: Etiology/Pathogenesis |
|
Definition
Most common cause of food poisoning!
Symptoms: occur within hours
-Projectile vomiting
-Diarrhea (less common) |
|
|
Term
| Staphylococcus aureus: Transmission |
|
Definition
| Food left unrefrigerated for long periods of time: reheating will not kill heat stable enterotoxin |
|
|
Term
| Staphylococcus aureus: Clinical ID |
|
Definition
G (+) cocci
Catalase (+)
Coagulase (+) |
|
|
Term
| Bacilus cereus: Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory) (although usually no diarrhea)
Bacterial Neurotoxin |
|
|
Term
| Bacilus cereus: Virulence Factors |
|
Definition
Pre-Formed Enterotoxin:
-Heat stable
-Emetic form
Heat-Labile Toxin:
-Formed in vivo
-Activates AC (fluid secretion)
-Diarrheal form |
|
|
Term
| Bacilus cereus: Etiology/Pathogenesis |
|
Definition
Emetic Form:
-Ingestion of pre-formed enterotoxin
-Rapid onset (short IP)
-N/V and abdominal cramps
-Only lasts ~24 hours (or less)
Diarrheal Form:
-LT forms in vivo
-Long IP (8-16 hours)
-Severe abdominal cramps and diarrhea
-Only lasts ~24 hours (or less) |
|
|
Term
| Bacilus cereus: Transmission |
|
Definition
Emetic form: Chinese restaurants (fried rice)
Diarrheal form: meat or vegetable containing foods after cooking (held above room temperature for long period) |
|
|
Term
| Bacilus cereus: Clinical ID |
|
Definition
|
|
Term
| Clostridium perfringens: Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory) (although usually no diarrhea)
Bacterial Neurotoxin |
|
|
Term
| Clostridium perfringens: Virulence Factors |
|
Definition
Enterotoxin:
-Only some C.perfringens (type A) produce this toxin |
|
|
Term
| Clostridium perfringens: Etiology/Pathogenesis |
|
Definition
Similar to B.cereus diarrheal form:
-Onset 8-24 hours after ingestion
-Abdominal cramps and watery diarrhea
-NO fever, N/V |
|
|
Term
| Clostridium perfringens: Transmission |
|
Definition
| Temperature abuse of prepared foods: meat, meat products, gravy |
|
|
Term
| Clostridium perfringens: Clinical ID |
|
Definition
|
|
Term
| Giardia lamblia: Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory) (although usually no diarrhea)
Non-inflammatory Parasitic |
|
|
Term
| Giardia lamblia: Virulence Factors |
|
Definition
Life Cycle: two stages
-Trophozoite: free living
-Cyst: infectious
Adhesion: via sucking disk on trophozoite
Motility: flagella |
|
|
Term
| Giardia lamblia: Etiology/Pathogenesis |
|
Definition
IP: 7-10 days after ingestion of cysts
Symptoms:
-Acute onset of watery diarrhea
-Abdominal cramps and bloating
-Flatulence
Can progress to chronic diarrhea with malabsorption: weight loss common |
|
|
Term
| Giardia lamblia: Transmission |
|
Definition
| Oral ingestion of cysts: often due to drinking contaminated water |
|
|
Term
| Giardia lamblia: Clinical ID |
|
Definition
Flagellated protozoa
Microscopic exam:
-Stool
-Duodenal aspiration
-Duodenal biopsy
Antigen Testing:
-Stool (ELISA)
String Test |
|
|
Term
| Crytosporidium parvum: Type of Diarrhea and Cause |
|
Definition
Secretory Diarrhea (Non-invasive and Non-inflammatory) (although usually no diarrhea)
Non-inflammatory Parasitic |
|
|
Term
| Crytosporidium parvum: Virulence Factors |
|
Definition
Life Cycle:
-Oocyst: infective
-Sporozoite: released from oocysts in intestine (infect microvilli) |
|
|
Term
| Crytosporidium parvum: Etiology/Pathogenesis |
|
Definition
Sporozoite: infects microvilli after being released in intestine and undergoes sexual and asexual reproduction; oocysts released in feces
Immunocompromise: severe, watery diarrhea (prolonged)
Immunocompetent: mild diarrhea |
|
|
Term
| Crytosporidium parvum: Transmission |
|
Definition
|
|
Term
| Crytosporidium parvum: Clinical ID |
|
Definition
| Coccidian protozoan parasite |
|
|
Term
| Cyclospora cayetanesis: Etiology/Pathogenesis |
|
Definition
Cause prolonged disease: up to 7 weeks long
More severe in AIDS
Cyanobacterium-like bodies |
|
|
Term
| Isospora belli: Etiology/Pathogenesis |
|
Definition
Clinically indistinguishable from other infections: giardasis, cryptosporidiosis and microsporidiosis
More severe in AIDS
Infects ENTIRE intestine |
|
|
Term
| Clostridium difficile: Type of Diarrhea and Cause |
|
Definition
Invasive and Tissue Damaging (Inflammatory)
Bacterial Cytotoxin |
|
|
Term
| Clostridium difficile: Virulence Factors |
|
Definition
Toxin-A Enterotoxin: causes accumulation of viscous, bloody fluid
Toxin B Cytotoxin:
-Decreases cellular protein synthesis (similar to diphtheria toxin)
-Disrupts actin polymerization and cytoskeletal architecture |
|
|
Term
| Clostridium difficile: Etiology/Pathogenesis |
|
Definition
Toxin A: chemotactic for PMNs, which lyse cells (releasing inflammatory mediators)
-Fluid secretion
-Altered membrane permeability
-Hemorrhagic necrosis of mucosa
Symptoms: variable
-Can by asymptomatic carrier
-Mild diarrhea
-Pseudomembranous colitis: fibrin, mucus, necrotic epithelial cells and leukocytes adhere |
|
|
Term
| Clostridium difficile: Transmission |
|
Definition
Endogenous to the environment: common cause of NOSOCOMIAL infections
Disruption of normal flora: due to Abx use |
|
|
Term
| Clostridium difficile: Clinical ID |
|
Definition
G (+) rod
Anaerobic
Spore forming
Special Media: CCFA
-Culturing not helpful
Toxin Tests:
-EIA test on stool (most clinically used) |
|
|
Term
| Enterohemmorrhagic E. coli (EHEC): Type of Diarrhea and Cause |
|
Definition
Invasive and Tissue Damaging (Inflammatory)
Bacterial Cytotoxin |
|
|
Term
| Enterohemmorrhagic E. coli (EHEC): Virulence Factors |
|
Definition
Adhesins: Tir and intimin (tight binding)
Shiga Toxin: AB toxin
-Binds Gb3 ganglioside
-Two types (I and II) and strains can carry one or both
-Encoded by bacteriophage
Type III Secretion:
-Inserts toxin and own receptor into host cell
Attaching and Effacing Lesions: form similar to EPEC |
|
|
Term
| Enterohemmorrhagic E. coli (EHEC): Etiology/Pathogenesis |
|
Definition
Shiga Toxin: modifies 28S ribosomal RNA of the 60S ribosomal subunit, blocking protein synthesis and causing cell death
IP: 3-4 days
Symptoms:
-Severe, crampy abdominal pain
-Copious watery diarrhea developing in bloody diarrhea
-Little to no fever
Hemolytic Uremic Syndrome: due to Shiga toxin damage to endothelial cells and renal glomeruli (esp. young kids)
-Acute renal failure
-Thrombocytopenia
-Hemolytic anemia |
|
|
Term
| Enterohemmorrhagic E. coli (EHEC): Transmission |
|
Definition
Fecal-oral: carried in the gut of cattle and other farm animals; ingestion of contaminated hamburger, milk and apple cider common
Only a small number of organisms need to be ingested for infection |
|
|
Term
| Enterohemmorrhagic E. coli (EHEC): Clinical ID |
|
Definition
G(-) rod
Lab Tests:
-Oxidase (-)
Serotyping:
-O157:H7: causes most infections
O157:H7 Tests:
-Sorbitol (-)
-Anti-O157:H7 serum
Shiga Toxin Tests:
-Cytotoxicity with Vero Cells
-DNA probe for genes |
|
|
Term
| Shigella: Type of Diarrhea and Cause |
|
Definition
Invasive and Tissue Damaging (Inflammatory)
Bacterial Invasive |
|
|
Term
| Shigella: Virulence Factors |
|
Definition
Invasion: primary VF
-Through M cells only
-Superficial
Type III Secretion: induces actin RAR causing pseudopods at surface of epithelial cell to take up bacteria
Actin-Based Motility: bacteria propelled through cells (enter adjactent cells; immune evasion)
Shiga Toxin: carried by S.dysenteriae type 1 (local destruction of mucosa) |
|
|
Term
| Shigella: Etiology/Pathogenesis |
|
Definition
Causes bacillary dysentery: blood and mucus in the stool
-Promotes cytokine release causing inflammatory response and damage to epithelium
-Damage results in more bacterial invasion
Actin-Based Motility: results in death of invaded cells and shallow ulcers on the gut wall (ulcerative colitis)
First 12 hours: small intestine (multiply here)
-Abdominal pain and cramping
-Fever
12-72 hours: now in colon
-Decreased fever
-More severe pain (lower quadrants)
-Dysentary develops (bloody, low volume diarrhea with PMNs in mucoid stool) |
|
|
Term
|
Definition
Only human to human spread: food, fingers, feces, flies
Highly infectious: only need a small number of organisms for infection |
|
|
Term
|
Definition
G (-) rod
Non-motile
Lab Tests:
-Lactose (-)
-Oxidase (-)
Serological Identification:
-Group A: S.dysenteriae
-Group B: S.flexneri
-Group C: S.boydii
-Group D: S.sonnei
Group D causes most US cases: the rest caused by Group B
-No cases of A or C in the US |
|
|
Term
| Salmonella: Type of Diarrhea and Cause |
|
Definition
Invasive and Tissue Damaging (Inflammatory)
Bacterial Invasive |
|
|
Term
| Salmonella: Virulence Factors |
|
Definition
Adherence and Invasion:
-Through M cells AND epithelial cells
-Binds microvilli and engulfed in a vesicle (replicates in phagosome)
Type III secretion: ruffling and bacterial-mediated endocytosis
Endotoxin: Lipid A of LPS released upon lysis
-Inflammatory response and mucosal damage |
|
|
Term
| Salmonella: Etiology/Pathogenesis |
|
Definition
Not as infectious as Shigella: requires much large inoculum
Gastroenteritis: most common
-Short IP
-Abrupt onset N/V/D with low fever
-Negative blood culture
-Positive stool culture
Bacteremia: rare
-Abrupt onset high fever
-GI symptoms absent
-Blood culture positive
-Stool culture rarely positive
Enteric (Typhoid) Fever:
-Long incubation period
-Gradual onset
-High fever
-Constipation followed by bloody diarrhea
-Chills, headache, anorexia, weakeness, myalgia, swollen LN, enlarged liver/spleen,
maculopapular rash
-Blood culture positive
-Stool culture negative early, positive after 2 weeks |
|
|
Term
|
Definition
Contaminated food: poultry meat or eggs
Found in almost all animal species: exception is S.typhi, which is found in only humans |
|
|
Term
|
Definition
Many seroptypes:
-Over 2400 based on O and H antigens |
|
|
Term
| Enteroinvasive E. coli (EIEC): General Characteristics |
|
Definition
Invasive and Tissue Damaging (Inflammatory)
Bacterial Invasive
No Shiga Toxin, but behaves like Shigella (infects and spreads cell-to-cell)
G (-) rod
Lab Tests:
-Oxidase (-) |
|
|
Term
| Campylobacter: Type of Diarrhea |
|
Definition
| Invasive and Tissue Damaging (Inflammatory) |
|
|
Term
| Campylobacter: Virulence Factors |
|
Definition
Motility: flagella (through mucus layer)
Toxins: destroy epithelial cells
-Enterotoxin
-Endotoxin (LPS)
-Cytotoxin
Protein S: surface protein that functions as capsule
-Blocks complement
-Resists phagocytosis |
|
|
Term
| Campylobacter: Etiology/Pathogenesis |
|
Definition
IP: 1-7 days
Symptoms:
-Fever and malaise
-Abdominal pain and cramps
-Profuse watery/bloody diarrhea
-PMNs in the stool
Guillan Barre Syndrome: autoimmune attack on nerve tissue 1-3 weeks after infection
-Similarities between myelin and surface of organism |
|
|
Term
| Campylobacter: Transmission |
|
Definition
Food: most commonly chicken
Can have a small infectious dose |
|
|
Term
| Campylobacter: Clinical ID |
|
Definition
Curved G (-) rod
Motile
Non-spore forming
Lab Tests:
-Oxidase (+)
Selective Media:
-No growth on Mac
-Incubate 42 degrees
-Microaerophilic
-Capnophilic
Stool Exam:
-Darting motility |
|
|
Term
| Vibrio parahemolyticus: General Characteristics |
|
Definition
Curved G(-) rod
Heat Stable Cytotoxin
Invades intestinal cells
Grows in brackish water (seafood) |
|
|
Term
| Yersinia enterocolita: Etiology/Pathogenesis |
|
Definition
Enterocolitis: due to necrosis of Peyer’s patches (1-2 weeks)
-Bloody diarrhea
-Fever
-Abdominal pain
Mesenteric lymphadenitis: can occur after invasion of ileum and lead to abscesses that mimic acute appendicitis in children
Transfusion related septicemia: grows at low temperatures and therefore can survive in refrigerated blood |
|
|
Term
| Yersinia enterocolita: Transmission and Clinical ID |
|
Definition
Carriage in livestock (pigs), rabbits and rodents: contaminated food, water or blood
G(-) coccobacilli
Lab Tests:
-Oxidase (-) |
|
|
Term
| Entamoeba histolytica: Type of Diarrhea and Cause |
|
Definition
Invasive and Tissue Damaging (Inflammatory)
Invasive Parasitic |
|
|
Term
| Entamoeba histolytica: Virulence Factors |
|
Definition
Life Cycle:
-Cyst: infectious
-Trophozoite: free living and invasive in tissue
Galactose-specific adhesion:
-Allows adherence to luminal surface
Proteolytic Enzymes:
-Dissolution of ECM
Cytolytic Enzymes |
|
|
Term
| Entamoeba histolytica: Etiology/Pathogenesis |
|
Definition
Causes amoebic dystentary: bloody and mucoid diarrhea
Trophozoites: colonize the colon and invade mucosa
-Erosion at base of crypts that progresses to ulceration
-Ulcers can extend to submucosa
Amebic Liver Absecess:
-Trophozoites can enter venules in the colon wall (RARE) and be carried to extraintestinal sites (most commonly liver) |
|
|
Term
| Entamoeba histolytica: Transmission |
|
Definition
|
|
Term
| Entamoeba histolytica: Clinical ID |
|
Definition
Stool Exam:
-Shedding of organism in stool
-Characteristic ultra-structure of cyst and/or trophozoite |
|
|
Term
| Rotavirus: General Characteristics |
|
Definition
Reoviridae Family
Linear, segmented (11) dsRNA genome
Unenveloped Icosahedral |
|
|
Term
| Rotavirus: Virulence Factors |
|
Definition
Direct Cellular Damage:
-VP4 (outer capsid) binds sialic acid or integrins on host cell
-Replicates in cytoplasm
-Damages transport mechanisms (no Na or glucose into cell)
Activation of Intestinal Nerves: stimulate water secretion from enterocytes |
|
|
Term
| Rotavirus: Etiology/Pathogenesis |
|
Definition
Infects cells at the tips of villi in small intestine: stomach and colon spared
Pathogenesis:
-Direct cellular damage
-Activation of intestinal nerves
IP: 1-4 days
Symptoms: acute onset N/V/D |
|
|
Term
|
Definition
Common in children: 6 months – 2 years
Seasonal: more common in the winter
Fecal-oral: may cause nosocomial infections as well |
|
|
Term
|
Definition
Very stable: resistant to extreme pH, ionic strength, temperature
Lab Diagnosis:
-Virus in stool if collected early in illness (ELISA, EIA, immunoassay)
-Rise in Abs to VP6 |
|
|
Term
| Norovirus: General Characteristics |
|
Definition
Calicivirus Family
(+)-single stranded RNA genome |
|
|
Term
| Norovirus: Virulence Factors and Etiology/Pathogenesis |
|
Definition
Antibody produced during infection: but confers NO long term immunity
Affect older kids and adults
IP: 1-4 days
Symptoms: similar to above
-Fever, headache, chills, N/V/D |
|
|
Term
| Norovirus: Transmission and Clinical ID |
|
Definition
Fecal-oral: associated with contaminated food (shellfish)
Spherical particles |
|
|
Term
| Adenovirus: General Characteristics |
|
Definition
Types 40 and 41
Endemic diarrhea in Kids
DNA Genome |
|
|
Term
| Astrovirus: General Characteristics |
|
Definition
Infections usually mild
Sporadic cases (babies, elderly) |
|
|
Term
| Chlamydia trachomatis: General Characteristics |
|
Definition
Obligate intracellular bacteria: but NOT an energy parasite (has own ATP transporters- only requires host ATP for persistent infection)
Cell wall similar to G(-): but lacks peptidoglycan
Affects more females than males |
|
|
Term
| Chlamydia trachomatis: Conditions Caused |
|
Definition
Often asymptomatic
Serotypes D-K cause urogenital infection:
Females:
-Cervicitis
-Salpingitis (lead to PID)
-Urethritis
-Chronic pelvic pain
Males:
-Urethritis
-Epididymitis
Neonates:
-Conjunctivitis
-Pneumonia
Serotypes L1-L3 cause Lymphogranuloma Venereum (LGV):
-Increases risk for HIV co-infection
-Treat the same way as Chlamydia
-No good treatment for systemic infection |
|
|
Term
| Chlamydia trachomatis: Virulence Factors |
|
Definition
Developmental Cycle:
Elementary Body: infectious, enters cells and is enclosed in vacuole (resist fusion with lysosome)
Reticulate Body: non-infectious and metabolically active; replicated in vacuoles to form inclusion bodies
-Inclusions derived from more than 1 EB fuse in the cell to form a single inclusion
-Mutations (ie. in lnc gene) can prevent fusion |
|
|
Term
| Chlamydia trachomatis: Pathogenesis |
|
Definition
Disease sequelae due to inflammatory response
Disseminates from primary site of infection: in mononuclear cells
Can become persistent: organism present and viable but not culturable
-Reduced expression of MOMP
-Increased expression of stress proteins (hsp60, hsp10) and LPS (chronic inflammation)
-May be induced by IFN-γ or the use of penicillin
LGV:
-Local: small papule on external genitalia/anus, swollen LN, mucoid anal discharge
-Systemic: fever, rashes, nausea (possibly meningitis or arthritis)
-Can become serious chronic/systemic disease |
|
|
Term
| Chlamydia trachomatis: Clinical ID |
|
Definition
Epithelial cells from infected site
-Scrapings
-First-catch urine
-Pus from genital lesions (LGV only)
Direct Detection:
-Fluorescent Abs to MOMP or LPS
-PCR
-Ligase chain reaction (LCR)
-Multiplex reactions (detect multiple STIs) |
|
|
Term
| Neisseria gonorrhoeae: General Characteristics |
|
Definition
Non-motile, G(-), diplococcic
Facultative intracellular bacterium: replicates in PMNs and subepithelial tissue; humans are the only host
Fastidious growth requirements:
-Inhibited by FAs
-CAP or Thayer-Martin plates
-37 degrees, CO2 enriched
Affects roughly equal amounts of men and women |
|
|
Term
| Neisseria gonorrhoeae: Conditions Caused |
|
Definition
Infections facilitate transmission of chlamydia and HIV: assume chlamydial co-infection and treat for it
Males:
-Urethritis (most common)
-Epididymitis
Females:
-Cervicitis (most common)
-Progress to PID
Disseminated Infection: rare
-Bacteremia
-Arthritis, dermatitis, endocarditis |
|
|
Term
| Neisseria gonorrhoeae: Virulence Factors |
|
Definition
Pili:
-Function:colonization
-Phase varation: expression vs. non-expression
-Antigenic variation: change pilus subunit expressed
Opa proteins:
-Function: close contact after pili bind and anchor
-Phase variation: expression (opaque colonies) vs. non-expression
-Constitutively transcribed: but translation controlled by CTCTT frameshifts
LOS:
-Structure: lipid A w/o O Ag
-Variation: sialyation confers serum resistance (dissemination)
-Proinflammatory
OMP1: used for serotyping
-Porin
IgA Protease:
-Cleaves IgA1 (secretory and non-secretory)
-Adherence in presence of IgA
-Loss of protease does not affect infectivity
Transferrin: iron acquisition
-Loss DOES cause loss of infectivity |
|
|
Term
| Neisseria gonorrhoeae: Pathogenesis |
|
Definition
Adherence: to mucosal surface following sexual contact
Invasion: can invade epithelial cells, but do not always
Mucosal Damage: due to granulocyte response |
|
|
Term
| Neisseria gonorrhoeae: Clinical ID |
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Definition
Direct Gram Smear:
-Only sensitive for symptomatic men
Culture:
-Diplococci within PMN diagnostic
Oxidase (+)
Direct Detection:
-Enzyme immunoassays
-DNA/RNA hybridization
-Multiplex PCR to detect chlamydia as well |
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Term
| Treponema pallidum (Syphilis): General Characteristics |
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Definition
Obligate human pathogen
G(-) spirochete
Outer glycosaminoglycan coating
Very motile (corkscrew)
Difficult to culture and does not stain by routine methods
Highly unstable: rapid death in environment and high sensitivity to antimicrobials
Metabolically crippled organism
Infects more men than women |
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Term
| Treponema pallidum (Syphilis): Conditions Caused |
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Definition
Chancres increase susceptibility to HIV transmission
Primary Syphilis: chancre development 3-4 weeks after contact on external genitalia
-Filled with bacteria
-Hard, red, painless
Secondary Syphilis: fever, sore throat, rash (palms/soles/face)
-After primary lesion has healed
-Filled with bacteria
-Some resolve via immune response, others go latent
Latent Syphilis: seroreactive but no signs or symptoms
-Variable length
-Can progress to tertiary symptoms if untreated or unresolved
Tertiary Syphilis: granulomatous gummas on the skin (due to host immune response)
-No bacteria in gummas
Neurosyphilis: tabes dorsals, seizures, dementia, NF tangles post-mortem
CV Syphilis: commonly aortic aneurysm
Congenital Syphilis: fetus susceptible at ANY time during gestation
-Often asymptomatic at birth
-Progresses to rhinitis, pneumonia and failure to thrive
-Can be fatal if severe |
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Term
| Treponema pallidum (Syphilis): Virulence Factors |
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Definition
Very little is known about the organism
Hyaluronidase: invasion
Outer membrane: few integral proteins (helps evade immune system)
Tpr (repeat genes): invasion |
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Term
| Treponema pallidum (Syphilis): Pathogenesis |
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Definition
Transmission:
-Direct sexual contact with an individual with active primary or secondary lesion
-Transplacental
Causes disease of blood vessels and perivascular area: invades mucus membranes, multiples rapidly, and spreads to systemic circulation BEFORE development of primary lesion |
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Term
| Treponema pallidum (Syphilis): Clinical ID |
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Definition
Darkfield microscopy: fluid from primary and secondary lesions
Serological:
VDRL/RPR: non-specific
-Positive during primary and secondary stages
-Reduction indicates successful treatment
-Many false +
Treponemal Tests:
-FTA-Abs: detects Ab specific to T.pallidum (present for life, so can’t be used to detect successful treatment)
-NERA-TP: microhemagglutination test
Genetic Probes: PCR (soon)
Congenital: anti-treponemal IgM diagnostic (IgM does not cross placenta- must be from fetus) |
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Term
| Haemophilus ducreyi (Chancroid): General Characteristics |
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Definition
Fastidious G(-) rod
Strict human pathogen |
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Term
| Haemophilus ducreyi (Chancroid): Conditions Caused |
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Definition
Increases susceptibility to HIV: due to chancroids
Chancroids: painful, genital ulcers with ragged edges |
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Term
| Haemophilus ducreyi (Chancroid): Pathogenesis |
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Definition
| Can infect abraded skin, mucosal surface and stratified squamous epithelium: chancroids 2-14 days later |
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Term
| Haemophilus ducreyi (Chancroid): Clinical ID |
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Definition
Antibody based detection
DNA probes
Multiplex PCR |
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Term
| Candida albicans (Vulvovaginal Yeast Infection): General Characteristics |
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Definition
Not really classified as an STI!
Fungi that is normal flora: GI tract, mucuocutaneous sites (vagina, mouth) |
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Term
| Candida albicans (Vulvovaginal Yeast Infection): Conditions Caused |
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Definition
Most common cause of vulvovaginal yeast infections
Predisposing Factors:
-Pregnancy
-Diabetes
-Oral contraceptives/hormones
-Antibacterial Abx
Recurrent Infections: can be caused even in healthy women
-Macrophage dysfunction? |
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Term
| Candida albicans (Vulvovaginal Yeast Infection): Virulence Factors |
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Definition
Multiple Forms: hyphae (tissue invasion) and yeast (pathogenic form in the body)
Adhesins: can bind fibronectin, collagen, laminin
Invasion: proteases and phospholipases produced by hyphal form
Biofilm formation: assists in pathogenesis
SAPs: proteinases only found in pathogenic yeast; pH regulated activity
-Determines level of tissue invasion
-Regulates other VFs |
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Term
| Candida albicans (Vulvovaginal Yeast Infection): Pathogenesis |
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Definition
Infection requires:
-Increase in local numbers of candida
-Compromised integrity of epithelial surface
Normal immune response: phagocytosis by macrophages (bind mannan wall) |
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Term
| Candida albicans (Vulvovaginal Yeast Infection): Clinical ID |
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Definition
-White-gray pseudomembrane on vaginal mucosa
-Yellow-white discharge
-Hyphal forms seen in vaginal scrapings |
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Term
| Trichomonas vaginalis (Trichomoniasis): General Characteristics |
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Definition
Highly motile, flagellated protozoan (parasite)
No cyst form: but can survive in moist environments
Most common STI worldwide |
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Term
| Trichomonas vaginalis (Trichomoniasis): Conditions Caused |
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Definition
Men: generally asymptomatic
Women: dysuria, vaginal itching and burning
-Severe infections produce foamy, yellow green discharge |
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Term
| Trichomonas vaginalis (Trichomoniasis): Virulence Factors |
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Definition
Coated with host-derived macromolecules: evasion?
-α1 antitrypsin, fibrontectin, α2macroglobulin, lipids
Phagocytosis: of bacteria, virus, RBC, PMNs
Upsets Flora: ingest lactobacilli |
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Term
| Trichomonas vaginalis (Trichomoniasis): Pathogenesis |
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Definition
Persistence: up to 90 days; worse during menses and pregnancy
Transmission: sexual contact (most often)
PMN inflammatory response: cell destruction |
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Term
| Trichomonas vaginalis (Trichomoniasis): Clinical ID |
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Definition
-Microscopic examinations of wet mount preparations (vaginal or urethra discharge)
-Culture of urogenital specimens |
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Term
| Uropathogenic E.coli (UPEC): Virulence Factors |
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Definition
Pili (Fimbriae) Associated Adhesins:
P Pili: associated with pyelonephritis
-Binds digalactosidase R
-Mannose insensitive
-Hemagglutinin (binds P Ags on RBC)
-Resists phagocytosis
-Proinflammatory
Type 1 Pili: associated with cystits
-Binds to mannose
-Mannose sensitive
-Hemagglutinin
-Turned on in bladder, off in kidney
Type S Fimbriae: associated with both
-Binds sialic acid on glycoproteins
-Mannose insensitive
-Neonatal meningitis/bacteremia
Afimbrial Adhesins: role in recurrent UTI
-AfaD and AfaE: adhesion to uroepithelium and internalization
-Dr adhesion: recognizes basolateral surface integrins to aid in internalization
Toxins:
-Alpha hemolysin: lyses RBCs to provide Fe for growth (kidney damage)
-CNF-1: kills human bladder cells by apoptosis (mutants without this less virulent)
LPS (Endotoxin): proinflammatory (synergistic effects with P pili)
K Antigen (Polysaccharide Capsule):
-Anti-phagocytic |
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Term
| Uropathogenic E.coli (UPEC): Etiology |
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Definition
Causes 80-90% of CA-UTIs
Source: own intestinal flora or sexual contact (partners flora)
More common in females |
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Term
| Uropathogenic E.coli (UPEC): Pathogenesis |
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Definition
-Bind urethra using Type 1 pili
-Ascend to bladder and bind using Type 1 pili (FimH tip)
-Move up urethra with flagellar motility
-Bind kidney with P Pili (PagG tip)
-P pili can Ag switch to evade immune system
Inflammatory response and toxins: lead to cell damage |
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Term
| Uropathogenic E.coli (UPEC): Clinical ID |
|
Definition
Gram Stain:
-G(-) rods, RBC and WBC
BAP:
-Beta hemolysis
-Quantitation (needs to be significant- over 105 cfu/mL)
Selective Media:
-MAC: lactose (+)
-CLED: yellow colonies (lactose +)
Biochemical:
-Indole Test: pink/purple
-Oxidase (-) |
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Term
| Staphylococcus saprophyticus: Virulence Factors |
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Definition
S.Saprophyticus surface associated protein
Hemagglutinin/fibronectin-binding protein
Hemolysin: not all uropathogenic strains
Urease: hydrolyzes urea (raises pH, increases risk of stone formation) |
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Term
| Staphylococcus saprophyticus: Etiology/Pathogenesis |
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Definition
Risk Factors: auto-infection, sexual activity, hormones (menstruation), spermicide
More common in females
Causes: urethritis and cystitis |
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Term
| Staphylococcus saprophyticus: Clinical ID |
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Definition
G(+) cocci in clusters
Special Media:
-Growth: CNA
-No growth: MAC, EMB, CLED
Biochemical:
-Catalase (+)
-Coagulase (-)
-Novobiocin resistant |
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Term
| Klebsiella pneumoniae: Virulence Factors |
|
Definition
Type 1 Fimbriae:
-Mannose sensitive
-Hemagluttinin
Type 3 Fimbriae:
-Mannose insensitive
-Hemagglutinin
Polysaccharide Capsule: bilayered
-Anti-phagocytic
-Causes mucoid colonies
LPS: serum resistance (O Ag)
Urease: stone formation |
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Term
| Klebsiella pneumoniae: Etiology/Pathogenesis |
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Definition
Normal flora: colon
Cause: pyelonephritis or complicated UTIs (rarely cystits)
Most often in people with underlying condition: diabetes |
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Term
| Klebsiella pneumoniae: Clinical ID |
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Definition
G (-) rod
Mucoid colonies
Special Media:
-MAC/EMB/CLED: lactose (+)
-BAP: non-hemolytic (distinguish from E.coli) |
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Term
| Proteus Miribalis: Virulence Factors |
|
Definition
Adhesins:
MR/P:
-Hemagglutinin
-Helps colonize urinary tract
-Increases risk for pyelonephritis
PMF:
-NOT a hemagglutinin
-Helps colonize bladder (not kidney)
Flagella: swarming motility
-Helps ascend to kidney
Urease: STRONG producer
HmpA Hemolysin: potent cytoxin |
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Term
| Proteus Miribalis: Etiology/Pathogenesis |
|
Definition
Normal flora: colon
Cause: pyelonephritis or complicated UTIs (rarely cystitis)
Most often in people with underlying condition |
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Term
| Proteus Miribalis: Clinical ID |
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Definition
G(-) rod
Smell: colonies REEK of ammonia
Special Media:
-MAC/EMB/CLED: lactose (-)
-BAP: swarming hemolysis |
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Term
| Enterococcus spp. (Group D Strep): Virulence Factors |
|
Definition
Aggregation Susbtance (Asa1):
-Normally facilitates plasmid exchange
-Adhesion to integrins
Cytolysin: lyses RBCs for Fe for growth
Sex Pheromones:
-Normally for plasmid acquisition
-Neutrophil chemoattractant (immune response triggered) |
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Term
| Enterococcus spp. (Group D Strep): Etiology/Pathogenesis |
|
Definition
Normal Flora: colon
Seen more in hospitalized patients with indwelling catheters |
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Term
| Enterococcus spp. (Group D Strep): Clinical ID |
|
Definition
G (+) cocci
Growth:
-Salt tolerant (6.5% NaCl)
-Grows on bile esculin plate
Biochemical:
-Catalase (-) |
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