Bacterial Physiology, Human Disease, and Antibiotics Flashcards by Uche PM

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

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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

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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

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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

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What is the significance of the vaginal yellow discharge in case 5?

Indicates that the colonizing bacteria was likely staph aureus

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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)

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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

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What were the 2 candidate diagnoses in case 5?

Staphylococcus aureus toxic shock syndrome (TSS)

Group A streptococcal (Streptococcus pyogenes) TSS

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Regarding the lab results, what chemistry values were elevated in case 5? What was low?

ALT AST CPK Creatinine BUN

Hypocalcemia

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What was the infecting organism in case 5 that caused the menstrual TSS?

MSSA staph aureus producing superantigen TSS1

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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

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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

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What are band neutrophils and when would you expect to see them elevated?

Immature neutrophils, elevated during infection

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What are some CNS findings associated with menstrual TSS?

Confusion and combativeness, without any focal neurological findings

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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

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Why is renal failure especially bad in menstrual TSS?

Because the toxin TSST-1 is cleared by the kidneys

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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

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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

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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

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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

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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

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Where is the lag phase longer, in people or in culture media?

In media, people have defense systems bacteria need to over come

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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

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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

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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

Bacterial Physiology, Human Disease, and Antibiotics Flashcards

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