Microbial Infection Flashcards
What is a zoonotic infection?
Does not normally circulate in the human population
Has an animal reservoir
What are the 5 types of infectious agents?
Viruses Bacteria Funghi Protozoa Helminths
What are the main features of viruses?
Not cells in their own right Obligate parasites Contain RNA or DNA as genetic material Replicate using host cell nuclear machinery Show host specificity Divide by budding out of host cell
How may a viral disease be transmitted?
Faecal-oral
Airborne
Insect vectors
Blood born
What type of virus is HIV?
Retrovirus
RNA genome requires reverse transcriptase
What is the only infectious disease to have been irradiated?
Smallpox
Which virus causes smallpox?
Variola virus
How was it irradiated?
By a effective vaccine
What method is being employed in the near-eradication of polio?
Effective oral vaccine
What are the main features of bacteria?
No internal membranes Single copy of genome (haploid) Poorly defined cytoskeleton Peptidoglycan cell well Divide by binary fission
How are bacteria motile?
Use flagella
Why may bacteria move?
Towards food sources
Away from toxins
What is an example of a bacterial infection?
Shingella
Affects GI tract invade epithelial cells
Moves within cells using host cell components
Faecal-orla transmission
What are the main features of Meningitis?
Community acquired Airborne Multiple serogroups Can cause septicaemia with 10% fatality Rapid preogression Septic chsock Severe inflammatory response Can result in meningitis if passes blood-brain barrier
What is a nosocomial infection?
A Hospital required infection
e.g. Clostridium difficile
Methicillin resistant staphylococcus aureus
What are the main features of TB?
1.5 million people die from TB each year
Chronic infection
Difficult to diagnosis
Effective drugs but take a long time to work (6 months)
BCG vaccine works well in infants and children not adults
What are the main features of leprosy?
Chronic infection of the skin and nerves
Transmitted by nasal discharges
5 year incubation period
What does helicobacter pylori cause?
Peptic ulcer and gastric cancer
What are the main features of pathogenic E.coli?
Zoonotic
Can mutate easily and rapidly
Short replication times (20 mins)
What are the main features of Funghi?
Eukaryotic Causes cutaneous, mucosal, systemic mycoses Occurs as yeasts, filaments or both Yeasts bud or divide Form hyphae
What are the main features of Protozoa?
Unicellular
Include instal, blood and tissue parasites
Replicate in host by binary fission
Or asexual reproduction
Many have complicated life cycles involving two hosts
Infection is acquired by ingestion or through a vector
Give two examples of diseases caused by protozoa?
Malaria and Leishmaniasis
What are the main features of Malaria?
Plasmodium species Infection acquired via mosquito vector Blood and tissue parasites Formation of trophozoites inside a cell Insect vector- mosquito Sickle-cell and Beta-thalassaemia are immune
What are the main features of Leishmaniasis?
Infection is acquired via a sandfly vector
blood and tissues parasites
Formation of trophozoites inside cell
What are the main features of Helminths?
Can be seen without microscope Metazoa with eukaryotic cells Life-cycle outside the human host e.g. Roundworms, flatworms and tapeworms Faecal-oral transmission
What are the main features of Schistosomiasis?
Adult worms in hepatic portal vein, eggs migrate towards gut
Ingested by snails which transmit Cercaria that is what causes infection in humans
Causes inflammation
