Microbiology 2- Bacterial Diseases Flashcards
List possible point of entries for bacterial infection (5)
Upper Respiratory Tract Urogenital Tract Broken Skin The Gastro-Intestinal Tract Mouth
List the 4 possible consequences of bacterial infection acquired via the upper respiratory tract
Upper Respiratory Tract Infection:
Pharyngitis
Tonsilitis
Sinusitis
Lower Respiratory Tract Infection:
Bronchitis
Pneumonia
Pneumonitis
Spread to Adjacent Tissues: Brain abscess Meningitis Empyema (plural space) Pericarditis
Spread to Blood Stream:
Bacteriaemia e.g. pneumococcal, meningococcal bacteraemia
Name 3 intrinsic bacteria in the large intestine which can cause infection
What 2 extrinsic methods of portal of entry of the urogential tract are there
Intrinsic - bacteria from the large intestine
E. coli
Klebsiella
Candida
Extrinsic
Nosocomial (hospital-acquired) -
Urinary catheters
Sexually Transmitted - Neisseria gonorrhoeae Chlamydia trachomatis Syphilis HIV, HSV
How can the skin get broken that leads to an infection
Surgery
Varicella - chicken pox causes areas of broken skin
Eczema
Pressure Sores
IDU - Injecting Drug Use
Unexpected Causes:
Human bites
List infections that target broken skin
Staphylococcus aureus - good at living on the skin - there is a lot in the nose and mouth
Streptococcus pyogenes - very good at getting into skin lesions
Most people have Staph. aureus in our nose and throat
If you’ve recently had antibiotics, you may get MRSA or pseudomonas
5 Consequences of infection via broken skin
If the infection spreads across the skin layer it’s called CELLULITIS - you get red inflammation of the skin
Abscess - pus filled pocket
Myositis - infection spread deeper into the muscle and causes inflammation
Gangrene/Necrotic Infection - any layer of skin or soft tissue can be subject to necrosis
Bacteraemia
List consequences of infections via GI tract
DIARRHOEA
Bacteremia/Systemic Infections
Typhoid (S. typhi)
Listeriosis (Lysteria monocytogenes)
Salmonellosis and septic arthritis, aortitis
Toxin-mediated disease
D & V (eg S. aureus enterotoxin)
Neurological (eg botulism)
What is the Pathogenecity of Bacteria
the ability of a bacterium to cause disease
Define Commensals
don’t cause disease
Define True Pathogen
can cause disease in normal, healthy people
Define Opportunistic Pathogen
can only cause disease when they are given the chance (if it’s given a leg up)
What is infectivity and what are the factors involved (5)
the ability to get into the host system and establish themselves
Factors involved: Transmission to host Ability to colonise host Ability to find unique niche Ability to replicate Immune evasion
What is Virulence and what are the factors involved (3)
features that enhance disease causation - enhance the bugs ability to make you unwell
Toxin Production -
e.g. pneumococcus makes a toxin which destroys bits of the lungs (pneumolysin)
Degradation of Host Molecules-
interference with Host Cell Function - e.g. S. aureus makes superantigens interfere with normal T cell function
Immune Evasion -
e.g. S. aureus makes leukocydins which causes neutrophil death and abscess formation
Define infectious dose
Infectious Dose - number of bacteria required to initiate an infection
Infectious Dose is affected by: Route of Transmission - e.g. stomach acid means that higher infectious dose is usually required Ability to Colonise Host Tropism and Motility Replication Speed Immune Evasion
Describe the Faeco-oral Transmission of Cholera
HUGE INFECTIVE DOSE
Use flagella to penetrate mucus
Makes 2 component toxins A+ B
These bind to GM gangliosides on gut
Triggers production of cAMP
CHLORIDE EFFLUX
Sodium ions and water flood out leading to watery stools
