Bacterial Physiology, Human Disease, and Antibiotics Flashcards
The patient In case 5 was an 18 year old. How would that be different today?
Majority of patients with menstrual TSS will be in the 11-13 y.o. range
What were the major presenting symptoms of the patient in case 5? (5)
Vomiting Diarrhea Progressively Increasing fever Dizziness (hypotension) Macular erythroderma on abdomen and face
By 13 y.o. 80% of people will have antibodies to TSST1 and 20% won’t. Who is suceptible to the menstrual TSS, people with or without the antibody? Is there a way to help these people?
People without the antibody developed
IVIG when infected, or monthly IM injections of antigen
Why do tampons make women more succeptible to menstrual TSS?
The vagina is usually anaerobic, tampons trap oxygen, and the TSS1 toxin requires oxygen to be made
What is the significance of the vaginal yellow discharge in case 5?
Indicates that the colonizing bacteria was likely staph aureus
Menstrual TSS is associated with what 5 cardinal signs?
Fever (Over 102) Hypotension (less than 90/X) Red rash (resembles sunburn) Peeling skin (palms and soles) Abnormal multiorgan changes (e.g. liver, platelets, mucous membranes)
What were the 2 drugs used to treat the patient in case 5? What 2 drugs would be used currently?
Nafcillin and Clindamyacin
Now, Use Vanco and Rifampin
What were the 2 candidate diagnoses in case 5?
Staphylococcus aureus toxic shock syndrome (TSS)
Group A streptococcal (Streptococcus pyogenes) TSS
Regarding the lab results, what chemistry values were elevated in case 5? What was low?
ALT AST CPK Creatinine BUN
Hypocalcemia
What was the infecting organism in case 5 that caused the menstrual TSS?
MSSA staph aureus producing superantigen TSS1
What is the significance of a left shift of WBCs?
Shows that the bone marrow was producing new WBCs, and some immature cells were being pushed out
What are the 2 organisms that can cause menstrual TSS? What is a major distinction between the 2?
Staph aureus and strep pyogenes (group A strep)
Staph A menstrual TSS will show staph limited to the throat and vagina, while Strep will most likely invade the bloodstream
What are band neutrophils and when would you expect to see them elevated?
Immature neutrophils, elevated during infection
What are some CNS findings associated with menstrual TSS?
Confusion and combativeness, without any focal neurological findings
Regarding drug treatment, what does it mean that the cultured organisms was MSSA? What is the antibiotic of choice for staphyloccocal TSS?
You can treat with penicillins and cephalosporins
Clindamycin
Why is renal failure especially bad in menstrual TSS?
Because the toxin TSST-1 is cleared by the kidneys
Why is clindamycin a good drug for the treatment of TSS?
Clindamycin is a protein synthesis inhibitor, and can prevent the manufacture of toxin even at concentrations below its antimicrobial range
While removal of The tampon (and trapped O2) helped in this case of menstrual TSS, in what case of menstrual TSS would removing the tampon not have helped?
If the causative agent was streptococcus pyogenes (group A strep), it would not have helped. Strep is an aerotolerant anaerobe
Regarding bacterial growth, what is the lag phase? log phase? stationary phase? Death phase?
Lag - enzymes being made to prepare for growth
Log - Exponential growth phase
Stationary - Nutrients used up, no more growth
Death - Bacteria are dying because of their toxic waste
What are The 2 significant types of bacteria regarding the death phase and how are they different?
Obligate fermenters die fast (hours) due to the presence of ROS, acid and H2O2 in the medium
Aerobes / oxidative bacteria can live for longer because of their metabolic enzymes
What phase of bacterial growth is associated with toxin production? How does this happen?
The post exponential phase, bacteria signal a quorum are present, initiating the production of exotoxin
Where is the lag phase longer, in people or in culture media?
In media, people have defense systems bacteria need to over come
What is an obligate aerobe? What enzymes does it have? What is the significance of these enzymes? What are the 2 examples provided?
Requires O2 to grow
SOD and catalase - convert superoxide amd acid eventually to water and oxygen
Bacillus and mycobacterium
What is a facultative anaerobe? What 2 enzymes do they have? What are the 2 examples provided?
Can grow in the presence (oxidative) or absence (fermentative) of oxygen
SOD and catalase
Staphylococcus and Escherichia
What is an aerotolerant anaerobe? What enzyme(s) do they have? What is the example provided?
Can grow in the presence of O2, but will still ferment
SOD (no catalase)
Streptococcus
What is an obligate anaerobe? What are the 2 examples provided?
Can only grow in the absence of O2
No catalase or SOD
Clostridium. Tetani
What are microaerophiles?
Aerobes that prefer a small amount of oxygen
Neisseria and Borella
What is a major anaerobic component of gut bacteria that that causes disease? Under what conditions will it cause disease?
Bacteroides
If the barrier is compromised
A bacteria described as gram positive cocci, clusters, catalase and coagulase positive is likely _
Staph aureus
A bacteria described as gram positive cocci, chains, SOD positive but no catalase is likely _
Streptococcus
A major difference between Staph and Strep is _
Catalase activity in staph but not strep
Bacterioides is an anaerobe that is able to survive in the human gut despite the presence of oxygen. Why?
Because other bacteria like e.coli use up the oxygen
Focusing on the gram positive cocci, a catalase positive cocci is likely _, If it is also coagulase positive, then the cocci is likely _
Streptococcus
Strep Aureus
A gram positive, catalase negative cocci is either _ (2). If it undergoes betahemolysis and is bacitracin sensitive, then it is _. If is undergoes alpha hemolysis and is optochin sensitive then it is _
streptococci or enterococci
Group A streptococci
Streptococcus pneumoniae
An gram positive cocci, obligate anaerobe is likely _
Peptostreptococcus
What are the 2 gram positive rods that are also aerobes?
– Corynebacterium (aerobe)
– Listeria (aerobe)
What are the 3 anaerobes gram positve rods discussed? Where are they found?
Propionibacterium Lactobacillus (dominant mucosal flora) Bifidobacterium (GI of breast fed babies)
What are the 2 spore forming gram positive rods?
Bacillus and Clostridium
What are the 2 gram negative cocci provided as examples? Which is a diplococci?
Neisseria (diplococci)
Acinetobacter
What are the 4 gram negative rods provided as examples?
- Enterobacteriaceae (facultative)
- Pseudomonadaceae (aerobes)
- Bacteroides, Fusobacterium (anaerobes)
A gram negative rod that is oxidase negative is likely _. What sort of test can be used to identify these organisms?
Enterobacteriaceae
Lactose utilization test
What are the 2 members of Enterobacteriaceae that are pathogenic and lactose negative? What diseases do they cause?
Salmonella - Typhoid and gastroenteritis
Shigella - Dysentery
The lactose positive members of the Enterobacteriaceae class are usually _ type of pathogen. 4 examples are _
Opportunistic E. coli Enterobacter Klebsiella Proteus
What is McConkey agar? What color does it turn for lactose positive organisms? What about lactose negative organisms?
Agar high in lactose, low in glucose
Lactose positive - Turn pink (acid products of fermentation)
Lactose negative - White (clear)
How do gram positive organisms grow in McConkey agar?
Poorly, Their growth is inhibited
What is another use for McConkey agar?
Used to determine coliform counts in fresh water lakes
How many steps are involved in the identification of Enterobacteriaceae?
2
Step 1- Mcconkey
Step 2 - several others, including Mass Spec. don’t need to know for lecture
What is a mesophile? What are 2 examples of pathogens that aren’t mesophiles?
Ability to grow at human temperature (most pathogens)
Mycobacterium leprae (skin)
Dermatophytes (skin)
What is the value of fever, especially since it can increase production of exotoxins?
Primitive immune response, idea being that some microbes (not necessarily pathogens) cannot grow well at elevated temps
What is an additional requirement of bacterial cells to be able to grow at fever temperatures? How do hosts keep this requirement away from bacteria?
Increased iron needed
Sequestering the iron in transferrin
What bacterial molecules are used to scavenge iron? How are they expressed?
Siderophores
Either cell associated or secreted
How can iron storage diseases affect bacterial pathogenicity?
Iron storage diseases where you can have increased iron can provide a required molecule for the bacteria to survive, even at elevated temperatures. Can increase opportunistic infections
What is the protein required for bacterial transcription? What are its 5 components? Where does it terminate and what does termination require?
DNA dependent RNA polymerase
2 alpha chains, 2 beta chains, 1 sigma factor for initiation
Hairpin turn, rho factor may be required
A specific type of bacteria that ciprofloxacin is effective against is _. A specific type of infection that norfloxacin is used to treat is _
Gram negative bacteria
Urinary tract infection
What is a specific use for metronidazole highlighted in the notes? What two types of bacteria does it target? What is its mechanism?
Trichomonas vaginalis (UTI) Anaerobes and microaerophiles Intercalates into DNA, prevents replication
What are the 4 examples of quinolone antibiotics provided? What is a specific risk associated with the fluoroquinolones? Which ones are they*?
Naladixic acid, Ciprofloxacin, * Norfloxacin, * Ofloxacin* * Weaken tendons, tendons burst / tear
What is the class of antibiotics that target the DNA gyrase? What is their mechanism?
Quinolone antibiotics
Block topoisomerase II and IV, prevent the formation of phosphodiester bonds
What is the protein required for DNA replication highlighted in the notes? What subunit of this protein was similarly highlighted in the notes?
DNA dependent DNA polymerase
DNA gyrase
What is the word used to described DNA replication? Where does it start?
Semi-conservative
At Ori, the origin of replication
What are 2 antibiotics that interfere with bacterial transcription? What is a special property of these drugs? What will these drugs do to urine? How are they administered and why?
Rifampin and rifamycin
High mucosal surface penetrating antibiotic
Cause urine to turn red
Used with other antibiotics, because of high chance of resistance if used alone
What bacteria will not develop resistance to rifampin even if used alone? What bacteria certainly will?
Neisseria will not develop resistance
Staphylococcus will
What is the major bacteria associated with 80% of enterocolitis? What is the bacteria associated with the other 20%
CLostridium difficile
Staph Aureus
What is a specific good use of clindamycin? What is a very serious risk associated with its use? What is an eukaryote specific side effect?
Inhibits toxins from many bacteria (blocks toxin synthesis)
Allows growth of clostridium dificil leading to pseudomembranous enterocolitis
Affects eukaryote membranes
The macrolide antibiotics include what 3 highlighted in class? What is a good use for these drugs?
Erythromycin, Azithromycin and clarithromycin
Used in penicillin allergic patients
Chloramphenicol is a drug that is used to treat gram _ bacteria, but it is rarely used today. Why? What compartment is it particularly good at penetrating?
Gram negative
Can cause aplastic anemia
CNS
Where do ribsosomes bind to initiate translation? What are the 2 components of the bacterial ribosome and what do they form? What are the 2 components of the eukaryotic ribosome and what do they form?
Shine Delgarno Sequence
30S and 50S form 70S ribosome (bacteria 357)
40S and 40S form 80S ribosome (euks 468)
What are the 4 examples of aminoglycosides highlighted in the notes? What are they used for? What is their mechanism? What are 2 toxicities associated with them?
gentamicin, amikacin, kanamycin, tobramycin
Used on hard kill gram negatives
Cause tRNA misreading, binds ribosomes cause to fall off
Ototoxicity and nephrotoxicity
What class of antibiotics Is particularly useful for treating pseudomonas in cystic fibrosis patients? What is pseudomonas’ gram classification? What setting is this class of drug used in?
Aminoglycosides
Gram negative
Hospital to monitor blood levels
Tetracyclines include what 2 drugs mentioned in the notes? What is their spectrum? What specific disease are they used to treat? Who shouldn’t use these drugs and why?
Tetracycline and doxycycline
Broad spectrum
Chronic acne
Infants and pregnant mothers, binds and stains calcium
What is a new protein synthesis inhibitor used for the treatment of MRSA?
Linezolid
What is a topical protein synthesis inhibitor mentioned in class? What is it used to treat (2)?
Mupirocin
- Staph and strep impetigo
- decolonize nose prior of staph aureus prior to surgery (with chlorhexidine)
Tetracyclines include what 2 drugs mentioned in the notes? What is their spectrum? What specific disease are they used to treat? Who shouldn’t use these drugs and why?
Tetracycline and doxycycline
Broad spectrum
Chronic acne
Infants and pregnant mothers, binds and stains calcium
Why is polymixin B not more widely used? What is its main current use?
Toxic because it affects all plasma membranes
Used on affinity columns to remove LPS
Beyond vancomycin, what other antibiotic can be used for MRSA?
Daptomycin
Why are Sulfonamides and Trimethoprim used in combination? Which is specific for bacteria? Which is selective? What type of bacteria do they target? What non-bacteria do they target?
Synergistic inhibitors of folic acid metabolism Specific - sulfonamide Selective - Trimetoprim Target aerobic and facultative Pneumocystis carinii - fungus
There are 6 antimycobaterial provided in class. What are they? How are they used?
Isoniazid Pyrazidamine Ethambutol Capreomycin Clofazamine Ciprofloxacin Cycloserine Rifampin Used in combination (2-3) for six months
What is the minimum inhibitor concentration vs. the minimum bactericidal concentration?
Minimum inhibitory - is amount to limit growth
Minimum bactericidal is amount enough to cause a 3 log drop in bacterial concentration
What is the Kirby Bauer test? What does it tell you?
Put a disc of antibiotic on a plate of bacteria and see how much it kills. Will tell you if bacteria are sensitive, intermediate or resistant
What do you need to see using the tube test to determine the minimum bactericidal concentration?
Need to see concentration where bacteria stop growing
