Gram Negative Rods Flashcards
3 Types of Gram - Infections
Non-invasive enteritis
Invasive enteritis
Systemic illness
Non-invasive Enteritis
Disease, Virulence Factors, Bacteria
- watery diarrhea; ehh WBCs
- non-fever
- Virulence Factors *
- adhesins
- exotoxins (change [NaCl]
- Vibrio Cholera*
- E coli: ETEC & EPEC
Invasive Enteritis
Disease, Virulence Factors, Bacteria
- Bloody diarrhea with WBCs!
- Involves Fever!
- Type III Factor/syringe*: invades and kills enterocytes
- endocytosis via M cells
- Virulence Factors*
- adhesins
- cytotoxin
- cell invasion
- Shigella
- Non-typhoidal Salmonella
- E. coli: STEC (aka Enterohemorragic E. coli [EHEC])
- Campylobacter jejuni
- H. Pylori
Systemic Infections
Disease, Virulence Factors, Bacteria
- early: +/- diarrhea
- later: systemic febrile illness (leaves intestine)
- Virulence Factors*
- adhesins
- cell invasion
- inhibition/killing of phagocytes
- Yersinia: intestine -> local lymph nodes
- Typhoidal Salmonella: intestine -> blood (systemic illness)
Vibrio Cholera
Non-invasive Enteritis
- endemic to SE Asia
- TCBS Agar: yellow colonies on salt agar; particularity resistant to salt
- Gram stain: curved rods
CHOLERA TOXIN; B5A1
- adds ADP-ribose to G protein
- stimulates Adenylate cyclase, increases cAMP; changes CL transport -> watery diarrhea
- massive watery diarrhea-> death
- treat with fluid; antibiotics shorten length of disease
ETEC
Enterotoxins E. coli
TRAVELERS DIARRHEA
- Pili adheres to intestinal wall
2 Exotoxins
- Heat Liable: resembles cholera toxin; produced in lower amounts
- Heat Stable: STructural analogue of peptide hormone
^ stimulates guanyl cyclase; increase cGMP-> change in chloride channels
^ watery diarrhea
EPEC
Enteropathogenic E. coli
STALK (EPEC)
|. |
- adhere to surface of enterocytes
- * Type III Structure: injects but doesn’t enter
- brush borders disappear => leaky cell wall => watery diarrhea
Shigella
Gram - Rod
- Invasive Enteritis
- Similar to E. coli, more severe with a very low infectious dose
- Actin tail (like listeria)
- * frequent, painful, low volume stool*
^ contains: blood, WBCs, and mucus
^ abdominal cramps
SHIGA TOXIN B5A1
- cleaves ribosomal RNA, inactivating ribosome
- toxin has SYSTEMIC effects (kidney)Shigella 4 Serotypes
Based on O Antigen
- S. Dysenteriae (most virulent, least common)
- S. Boy did, S. flexner
- S. Sonnei (least virulent, most common)
STEC
Gram - Rod
Aka EHEC (enterohemolytic E. coli)
- EPEC w/ SLT
- predominant serotype O157:H7
- *SORBITOL NEGATIVE*
- principal host: cattle
^ infection from fecal contamination of hamburger meat, apply cider, or H20Non-typhoidal Salmonella
Gram - Rod
- Human infection: meat, eggs, sometimes reptiles
- Type III induces apoptosis in macrophages
- gastroenteritis
- diarrhea, fever, vomiting
Campylobacter jejuni
Gram - Rod
- Campy ~~~~: curved
- Guillian Barre Syndrome (CNS)
- transmitted from contaminated food (chicken)
- ID with CAMPY-BAP: 42C
H. Pylori
Gram - Rod
- peptic ulcers; MALT lymphoma; gastric cancers
- Type IV
- Urease: urea -> ammonia + CO2 (breath test)
- chronic infection/inflammation
- Diagnose with:
- gastric biopsy
- breath test
- standard antigen assay
Yersinia
Gram - Rods
Intestine —> Local Lymph Nodes
Y. Entercolitica; Y. Pseudotuberculosis
- Type III translocates proteins; inhibits phagocytosis
- Painful inflammation of lymph nodes
^ can mimic appendicitis
- *Grows at 4C* (refrigeration temp)
^blood products!
(Like listeria)Typhoidal Salmonella
Gram - Rods
Intestine —> Blood! (Systemic)
- unique to humans
- M cell penetration (not Type III)
- capsules = virulence factor
- *do NOT cause Macrophage apoptosis*
^ keep phagocytes alive, grow within them, then hitch a ride through the body
- Chronic Carrier State: Gallstones!
