Bacteriology & Microbiology Flashcards
What is bacterial conjugation and how does it occur
A form of bacterial reproduction by passing DNA fragment, the fertility factor, from one F+ bacterium to a F- through a conjugation tube formed as the two cell membranes fuse together.
What are the processes in which bacteria transfer DNA fragments between each other
- Trasnformation - Bacteria picking up DNA fragments from the environment usually released by dead bacteria
- Transduction - The carrying of bacterial DNA from one cell to another by a virus.
- Mutation
These are ways inwhich antibiotic resistance is passed down
What strains of bacteria can produce and secrete spores
- Bacillus
- Clostridium
What are bacterial spores (endospores)
Endospores are small fragments of bacterial DNA encased by a tough cell wall that is resistant to extreme conditions such as temperature, pH, drying and ohter chemicals.
They are released when environmental conditions become unfavourable as means of survival for the bacteria.
Gram positive bacteria characteristics
- HIGH amounts of peptidoglycan (thick cell wall)
∴ sensetive to penicillin and lysosomes - Not sensetive to mechanical pressure
Gram negative bacteria characteristics
- LOW amounts of peptidoglycan (Thin cell wall)
∴ NOT sensetive to penicillin - Two cytoplasmic membranes
∴ Inner phospholipid bilayer
∴ Outer leaflet of outer membranes is mainly composed of lipopolysaccharides - Periplasmic enzymes in periplasmic space
- Sensetive to mechanical pressure
What catalyses the synthesis of peptidoglycan and how antibiotic resistance an occur
Penicillin binding protein and they can mutate into a strain that is no longer sensetive to penicillin drugs
TRUE OR FALSE
Gram positive bacteria contain periplasmic enzymes that can hydrolyze drugs
FALSE
Only gram negative bacteria contain periplasmic enzymes
Why does the inhibition of PBPs in gram negative bacteria not necessarily lead to apoptosis
Bc their defence is not mainly dependent on the peptidoglycan wall as they have other means of defence also.
What are endotoxins and what complications do the present in pharmaceutics
Endotoxins are lipopolysaccharides most commonly found in the outer membrane of gram negative bacteria cell and they are pyrogenic (cause fever). Some medications can consist of endotoxins which, when administered, increase the endotoxin concentration in the body = Harmful
How can we test for endotoxins in medication
BP test for pyrogens
* 3 rabbits are administered with the drug
* Temp is taken every 30 minutes for 3 hours
* An increase to their temp indicates pyrogen presence
Limulus amoebocyte lysate test
* Horseshoe crab blood is mixed with a product sample
* Coagulation of the blood indicates presence of endotoxins
What are the limitations of the BP test for pyrogens
- Rabbits may be tolerant to pyrogens (to a certain degree)
- Biological variations
- Test is unsuitable for many classes of drugs
What are the limitations of the Limulus amoebocyte lysate test
- Test cannot be conducted on viscous products
- Only sensetive to gram negative endotoxins
- Certain chemicals can inhibit the interaction between LAL substrate and the endotoxin
What enzyme targets and inhibits penicillin drugs and how
penicillinase / β-lactamase
* They target the β-lactam ring in penicillin chemical structures and break it down
they are the same
What is horizontal transmission and give examples
The spread of pathogens to the same or different species in a population through non-hereditary means (i.e droplet inhalation etc)
Examples: Polio, thypoid, covid-19
What is vertical transmission and give examples
The transmission of disease from mother to child (hereditary)
Examples: HIV, Rubella
What are anthroponoses and how are they transmitted
Diseases that are transmitted from human to human. They are transmitted via…
* Droplet inhalation
* Fecal-oral spread
* Venereal spread (sex)
What are arthropod-borne diseases & zoonoses and how are they transmitted
Diseases that are caused by pathogens that are transmitted by animals or arthropods. Methods of transmission include…
* Vector (biting)
* Vertebrate reservoir - Diseases that reside in animals and can jump to humans
* Vector-vertebrate reservoir
What bacterium causes lyme disease and what does it look like
Borrelia burgdorferi
* Starts as an expanding annular rash
What causes gonorrhoea and what are some key characteristics
Neisseria gonorrhoeae
* Can be transmitted both horizontally and vertically
* Vertical transmission causes destructive eye disease (Ophthalmia neonatorum)
What are the complication of local spread gonorrhoea
Female
* Damage to fellopian tubes
* Pelvic inflammatory disease
* Anorectal infection
Male
* Occasional epididymitis
What are the systemic complications of gonorrhoea
- Skin lesions
- Endocarditis
- Arthritis
What causes the bubonic plague and what are the mortalities for each stage
Yersinia pestus
* Bubonic plague - 1-15% (treated) |40-60% (untreated cases)
* Septicemic plague - 40% (treated) |100% (untreated)
* Pneumonic plague - 100% if not treated within 24hrs
How is bubonic plague transmitted
- Rat flea / wild rodent flea
- Flea bites human
- Bubonic plague infects (no human transmission)
- Pneumonic plague develops (rapid human-human transmission)
What are the three stages of borrelia burgdorferi
- Expanding annular rash (at the site of the bite)
- Headache, fever
- Arthritis
What is pneumonia and what are the different causes
Inflammation of the lungs caused by viral pathogens such as parainfluenza in children. In adults the causes are more commonly bacterial but can also be viral.
How is cholera spread and when are cases at their highest
Cholera spreads through contaminated water sources and this most commonly happens when disasters occur such as earthquakes, tsunamis and hurricanes.
Describe the mode of action of cholera
- Vibrio cholera introduced into the system
- Cholera toxin released
Contains α & β subunits - β-subunit binds to GM1 receptors in intestinal tract
- α-subunit diffuses into the cell
- Binds to and activates Gas, which stimulates adenylyl cyclase
- Production of cAMP
- cAMP activates CFTR
- CFTR pushes Cl- out of the cell (Na+ and water also follows) into the intestinal tract = Watery diarrhoea
What are the complications of Gastrointestinal anthrax
- Haematemesis
- Severe diarrhoea
What are the complications of pulmonary anthrax
Initially presents with flu-like symptoms ollowed by severe respiratory problems that are fatal. Mortality ~100 % if not treated prior to symptoms presenting
What are the complications of cutaneous anthrax
Initially presents as an itchy skin lesion OR a dark blister which develops into a large, painless necrotic ulcer after ~ a week of exposure
What is Staphylococcus aureus and its most common complications
A spherical, gram-positive bacterium that lives on the skins and nasal membrane. It consists of different strains caused by different Staphylococcal toxins. Common complication include…
* Boils
* Pimples
* Wound infections
* Pneumonia
* Toxic shock syndrome
What is MRSA
Methicillin resistant staphylococcus aureus is resistant to many antibacterials including penicillins and can be treated with vancomycin. It is usually confined and contracted in hospitals.
What are some brief complications of having to use vancomycin
It is an expensive and toxic drug that can only be administered via intravenous infusion
What is SSSS and what causes it
Staphylococcus scaled skin syndrome is caused by an exfoliative toxin mainly in infants and young children
Briefly describe the various staphylococcal toxins and their complications
- Alpha-toxin -> Disrupts smooth muscle in blood vessels ∴ prevents wound healing
- Beta-toxin -> Neutral sphingomyelinase is a toxic enzyme that can harm many types of cells, including fibroblasts, erythrocytes, leukocytes, and macrophages
- Delta-toxin -> Prevents wound healing
- Gamma-toxin -> Prevents wound healing
- Exfoliative toxin -> Causes SSSS
- Enterotoxins -> Causes food poisoning
- Toxic shock syndrome toxin-1 (TSST-1) -> Causes toxic shock syndrome
How do you treat Corynebacterium diphtheria
Antibiotic treatment + Antitoxin treatment
What are the complications of Corynebacterium diphtheria
- Bacteria release a toxin which destroys epithelial cells in the pharynx
-> Ulcer covered in necrotic exucate forms which obstructs airway - Toxin can also cause heart failure
- If absorbed into the blood, it can cause myocarditis, polyneuritis and fever
What are enteric bacteria and give examples
Gram-negative, rod-shaped bacteria that reside in the intestinal tract. They are facultative anaerobes. Most are harmless but there are some pathogenic ones…
* E.coli
* Shingella dysenteriae