Bacterial Infection Flashcards
What are sterile sites?
Places where bacteria exist only pathologically:
- blood
- CSF
- urine
- peritoneal fluid
- pleural fluid
How do bacteria cause disease?
- direct: rupture, obstruction, pressure, cell destruction
- exotoxins
- pathogenic activation of immune system
What makes pathogenic bacteria distinct from the natural flora?
- acquire virulence factors
- gain access to deeper tissues
- immunocompromised patients
Name a bacterium that is always pathogenic
M. tuberculosis
Name three bacteria that are usually part of the gut flora but which may acquire virulence factors
- E. coli
- Staph aureus
- N. meningitidis
What were Koch’s postulates?
- Pathogen present in bacterial disease
- Culture grown
- Disease replicated through inoculation of susceptible healthy host
- Pathogen recoverable from 2nd host
What’s the difference between colonisation & infection?
Infection - invasion & growth
Colonisation - presence & replication WITHOUT interaction with host
What is the difference between Gram +ve and Gram -ve bacteria?
+ve: thick peptidoglycan, purple stain
-ve: thin peptidoglycan, pink stain
Gram -ve rods
Reservoir: gut
Path site: biliary tree, urine
e.g.: E.coli, shigella, Klebsiella
Gram +ve rods/bacilli
Reservoir: soil
Path site: wounds
e.g.: C.diff, listeria, gardnerella, bacillus
Gram -ve cocci
Reservoir: (depends)
Path site: urogenital, URT
e.g.: pasturella, neisseria
Gram +ve cocci
Reservoir: skin, genitourinary
Path site: systemic, fascia, skin
e.g.: staph aureus, streptococci
Spirochaetes
Reservoir: free living/host
Path site: genitourinary
e.g.: leptospirosis, syphylis
Rickettsia
Reservoir: zoonoses
Path site: endothelial, lungs
e.g.: Q fever, scrub typhus
Mycobacteria
Reservoir: environment & ppl
Path site: lungs, skin
e.g.: TB, M.leprae
