Intro to Microbes Flashcards
What is the structural difference between gram positive and gram negative?
Gram positive have a thick petidoglycan layer.
Gram negative can have a lipopolysaccharide outer membrane that is toxic and antigenic. Gram negative thus have two cell membranes separated by thin peptidoglycan and periplasmic space.
What is the difference between endotoxins and exotoxins?
Endotoxins are integral to the bacterial structure and toxic to eukaryotic cells.
Exotoxins are secreted by the bacteria and toxic to eukaryotic cells.
What is glycolax?
Bacteria make a sticky extracellular coating made of polysaccharides. Function to help adherence, antiphagocytic, barrier for antibiotic diffuse.
Name two bacterial appendages.
- Flagela - helical hollow tubular structure containing flagelin. Help movement of bacteria in chemotaxis, tend to from diffuse cultures not colonies. Highly antigenic.
- Pili- short and thin, promote cell to cell contact (between bacteria and host or multiple bacterial cells.)
What is antigenic variation?
The ability of microbes to change the antigens they present giving rise to different strains. Eg Neisseria
What are spores?
Most resistant life forms known. They are made to withstand hotel environments by bacteria. Spores have no metabolic activity, little water, no division, impermeable with a multilayered envelope just containing bacterial DNA. Eg clostridium difficile
List the stages of bacterial growth.
Lag phase
Log phase
Stationary Phase
Death phase
Order pathogens in from biggest to smallest and give broad subcategories.
Virus - DNA and RNA viruses
Bacteria- Gram + and -
Fungi - yeast and mould
Paraste - protazoa and helminth (worms)
Name two broad categories of treatment?
Supportive and specific
What colour is a gram positive bacteria when stained?
Purple
How does a gram stain work?
Add crystal violet and iodine and stain all cells purple. Then wash with a solvent like alcohol and only gram positive will retain the purple stain. Gram negative will be red.
Name some gram negative bacteria:
Neisseria Meningitidic Haemophillis influenza Eschericha Coli Salmonella Typhi Legionella pneumophila
Name some gram positive bacteria:
Staph Aureus Staph epidermis Strep pneumoniare Viridans Strep Strep pyogenes Clostridium Difficile
Name some viruses we have studied:
Adenovirus Norovirus Epstein-Barr virus HIV Hepatitis B and C Herpes Zoster Dengue Ebola
Name some parasites we studied:
Malaria
Shistomiasis
Name some fungi we have covered?
Candida
Aspergillus
Name some investigations we should do in suspect infections.
FBC, CRP, Imaging
What additional tests are important to monitor query sepsis.
Blood pH, Lactate, clotting factors.
O2 Sats, LFT and Renal function
How do we identify the bacteria?
Culture and sensitivity sample Gram stain Antigen, antibody testing Blood film in malaria PCR for microbe DNA
How do we know what the best anti microbial is?
Disk diffusion method
Minimal inhibitory concentration
What antibiotics do we know about?
Penicillin Flucloxacillin Cefuroxime Vancomycin Trimethoprim Metranidazole
Name some viral therapies:
Acyclovir
anti retrovirals
Give some features of the structure of viruses:
mRNA or DNA genetic code- double or single stranded.
Smaller than host cells- has to live inside host cell and use its machinery to replicate.
Spikes for epithelial attachment
Protein coat
Lipid envelope.
(Not all viruses have all of the above)
Name some double stranded DNA enveloped viruses
Herpes
Hepatitis B
Name some double stranded DNA non-enveloped viruses
Adenovirus, HPV
Give an example of one single stranded none enveloped DNA virus
Parvovirus
List some single stranded RNA viruses non enveloped
Norovirus, Hepatitis E+A
List some single stranded enveloped viruses.
HIV and Hep C
What new virus is an enveloped single stranded virus
Ebola
What is a bacteriophage?
A bacteria that can infect a virus
Outline basic bacterial structure
Pili and or flagella Cytoplasm Ribosomes Polysaccharide capsule (poor immunogenic properties) Cell wall Plasma membrane
What shapes are bacteria?
Coccus, spirillus or bacillus
How can bacteria group together?
clusters or chains
What are obligate aerobes?
Need O2 to survive
What are obligate anaerobes?
Need an O2 free environment to survive unless in spore form.
How do we name bacteria?
Genus + species
Name some virulence factors.
Host entry (poly saccharide capsule.) Adherence to host cell (pili) Invasiveness (enzymes) Iron sequestration Toxins- endo or exo
