Introduction To Microbes Flashcards
What categories can the microorganisms responsible for human disease be broken down into?
Viruses
Bacteria
Fungi
Parasites
Give an example of a virus?
Human Immunodeficiency Virus (HIV)
Give an example of a bacteria
Nisseria Meningitidis
Give an example of a fungi
Thrush
Give an example of a parasite
Plasmodium falciparum
What does plasmodium falciparum cause?
Malaria
What are viruses?
Obligate intracellular parasites without a cellular structure
What do viruses consist of?
Molecule(s) of either DNA or RNA (but not both) surrounded by a protein coat
May also have an envelope
What is a viruses envelope derived from?
The plasma membrane of the host cell from which its released
What do viruses do?
Hijack the host’s mechanisms for creating mRNA and production of proteins to reproduce
What is the classification of viruses based on?
Their structure
What structural features can viruses be classified based on?
Single or double stranded Enveloped or not Positive or negative strand Icosahedral or helical DNA or RNA
Give an example of a single-stranded, non-enveloped DNA virus
Parvovirus 19
What can parvovirus 19 cause?
Mild infections in children
Fetal development issues in pregnant women
Give two examples of double-stranded, non-enveloped DNA viruses
Adenovirus
Human papilloma virus (HPV)
What can adenovirus cause?
Pharyngitis
Conjunctivitis
Infantile gastroenteritis
What does HPV induce?
Hyperplastic epithelial lesions of either cutaneous or mucosal epithelium
What do a small number of HPV virus types produce?
Lesions that have a risk of progressing to malignancy
Give an example of a malignancy that can arise from HPV infection
Cervical carcinoma
Give two examples of double-stranded, enveloped DNA viruses
Herpes
Hepatitis B
What are the types of herpes infections?
Primary HSV-1
Latent HSV-1
Primary HSV-2
Latent HSV-2
What can primary HSV-1 infections cause?
Tonsillitis and pharyngitis in adults
Gingivostomatitis in young children with ulcer forming usually in the oropharynx
What can latent HSV-1 infections cause?
‘Cold sores’ to appear on or around the lips
What can primary HSV-2 infections cause?
Lesions in the genital tract, similar to those found in the oropharynx in primary HSV-1 infections
What can latent HSV-2 infections cause?
Often asymptomatic
What does hepatitis B cause?
Acute hepatitis and later chronic liver disease
Give two examples of single-stranded, positive strand, icosahedral, non-enveloped RNA viruses?
Hepatitis A/E virus
Norovirus
How is hepatitis A/E most commonly spread?
Through fecally contaminated waters
What does the hepatitis A/E virus cause?
Hepatitis and impaired liver function
What is norovirus also known as?
The winter vomiting bug
What is norovirus the leading cause of?
Acute gastroenteritis
Where is norovirus common?
In closed environments, such as schools, hospitals, prisons, and cruise ships
Give 3 examples of single-stranded, positive strand, icosahedral or helical, enveloped RNA viruses
HIV
Hepatitis C
Rubella
How is HIV transmitted?
Sexually
Exchange of blood produces
Perinatally
How is HIV transmitted perinatally?
Transplacentally
During passage through the birth canal
By breastfeeding
What does HIV cause?
Acquired Immune Deficiency Syndrome (AIDS)
What does HIV and AIDS allow?
Increasingly frequent and serious opportunistic infections to occur
What does the hepatitis C virus cause?
Destruction of liver cells
How does the hepatitis C virus cause destruction of liver cells?
Through viral replication and host response
How hepatitis C transmitted?
Via the blood
How is the rubella virus spread?
Via respiratory secretions
What does the rubella virus result in?
German measles
What can the rubella virus cause in the developing fetus?
Extreme congenital defects
When can the rubella virus cause extreme congenital defects?
During the first trimester, when a pregnant woman is infected
Give four examples of single stranded, negative strand, helical, enveloped RNA viruses?
Ebola
Measles
Mumps
Influenza
How is the measles virus spread?
Respiratory droplets
What does the measles virus cause?
Fever
Cough
Eventually a rash
How is the mumps virus spread?
Respiratory droplets
What does the mumps virus cause?
Swelling of the parotid glands
How is influenza spread?
Respiratory droplets
What does influenza cause?
Fever
Muscle aches
Extreme drowsiness
Give an example of double-stranded, icosahedral, non-enveloped RNA virus
Rotavirus
What does rotavirus cause?
Severe viral gastroenteritis in infants and young children
What are bacteriophages?
A class of virus that infect bacteria
Where do bacteriophages play a key role?
Transmitting genetic material between different types of bacteria
What are true bacteria also known as?
Eubacteria
What kind of organisms are true bacteria?
Prokaryotic
What common structural organelles do most bacteria share?
Capsule Cell wall Plasma membrane Cytoplasm Ribosomes Plasmid Pili Bacterial flagellum Nucleoid (circular DNA)
Do all bacteria possess a capsule or flagellum?
No
What is the classification of bacteria based on?
Their overall shape identified under a microscope
What are the classifications of bacteria?
Coccus
Spirillus
Bacillus
What shape are cocci?
Circular
What shape are spirillus?
Spiral
What shape are bacillus?
Rods
How can cocci be arranged?
Clusters
Chains
Pairs
What is the bacterium called when it has cocci arranged in clusters?
Staph
What is the bacterium called when it has cocci arranged in chains?
Strep
What is the bacterium called when it has cocci arranged in pairs?
Diplo
What is used to help make bacteria visible under a light microscope?
A technique known as the Gram stain
What colour do gram positive bacteria appear with a gram stain?
Blue/violet
What colour do gram negative bacteria appear with a gram stain?
Red
What is whether a bacteria is gram negative or gram positive determined by?
The composition of its surrounding wall and membranes
What does the cell membrane of gram positive bacteria consist of?
Plasma membrane
Periplasmic space
Peptidoglycan
What does the cell membrane of gram negative bacterium consist of?
Plasma membrane
Periplasmic space
Peptidoglycan
Outer membrane
What does the outer membrane of gram negative bacterium consist of?
Lipopolysaccharide and protein
How does the cell membrane of a gram positive bacterium differ from a gram negative?
Thicker peptidolycan wall
What is the result of the thicker peptidoglycan wall of the gram positive bacterium?
Often causes host response
How can the cell wall of gram negative bacterium cause disease?
Present of lipopolysaccharides, which often acts as endotoxins
How do bacteria vary in their oxygen tolerance?
Aerobes can survive in the presence of oxygen, whereas anaerobes can survive in the absence of oxygen
What are obligate aerobes?
Bacteria that require oxygen to survive
What are obligate anaerobes?
Bacteria that require an oxygen free environment for survival
When can obligate anaerobes survive in an oxygen rich environment?
If they can form spores
On what characteristics can a bacteria be identified?
Gram staining
Shape
Arrangement
What can be done by identifying a bacterias characteristics?
Allows clinicians to narrow down the antimicrobials that should be used
Give 6 medically important gram positive cocci
Staph aureus Coagulase negative staph Alpha-haemolytic streptococci Beta-haemolytic streptococci Streptococcus pneumoniae Enterococcus faecalis
Give an example of a beta-haemolytic streptococci
Strep pyogenes
Give 4 medically important gram negative cocci
Neisseria meningitidis
Neisseria gonorrhoeae
Moraxella catarrhalis
Acinetobacter baeumannii
Give 3 medically important gram positive bacilli
Listeria monocytogenes
Bacillus anthracis
Bacillus cereus
Give 6 medically important gram negative bacilli
Escherichia coli Klebsiella pneumoniae Proteus species Salmonella typhi Pseudomonas aeruginosa Haemophilus influenzae
How do prokaryotes and eukaryotes differ in terms of chromosomes?
Prokaryotes are circular, usually single, and extra-chromosomal DNA may also be present (plasmids). Eukaryotes have multiple chromosomes
How do prokaryotes and eukaryotes differ in terms of their nucleus?
Prokaryotes have no nuclear envelope or nucleoli, whereas eukaryotes have membrane bound nucleoli present
How do prokaryotes and eukaryotes differ in terms of membrane-bound organelles?
Prokaryotes do not have them, whereas eukaryotes do
How do prokaryotes and eukaryotes differ in terms of cell wall?
Prokaryotes usually have a cell wall present, whereas eurkaryotes only have them in plant cells
What may the prokaryote cell wall contain?
Peptidoglycan
Do eukaryote cell walls have peptidoglycan?
No
How do prokaryotes and eukaryotes differ in terms of plasma membrane?
In prokaryotes, there is no carbohydrates and most lack sterols.
In eukaryotes, sterols and carbohydrates present
How do prokaryotes and eukaryotes differ in terms of ribosomes?
Prokaryotes have 70S ribosomes, eukaryotes have 80S (but 70S in organelles)
What are yeasts?
Single-celled fungi
Give three examples of yeasts
Candida albicans
Cryptococcus neoformans
Pneumocystis jiroveci
What are molds?
Multicellular fungi
Give two examples of molds
Aspergillus species
Dermatophytes
Give two examples of dematophytes
Ringworm
Athletes foot
What are protozoa?
Single celled parasites
Give 4 examples of protozoa
Giardia lamnbia
Cryptosporidium falciparum
Plasmodium falciparum
Typanosoma cruzi
What are helminths?
Multicellular parasites, worms
Give three examples of helminths
Roundworms
Tapeworms
Flukes