Bacteria, ABX Master Study Flashcards
What are bacteria and how big are they?
Prokaryotes, no nucleous, no organelles, infectious, may have toxins, .5 - 5 microns.
What are Protazoa?
Eukaryote, nucleated with organelles, infectious no toxins, 15 - 30 microns. Ex: malaria
What are fungi?
Eukaryote, nucleated with organelles, infectious but might have toxins, 5 - 10 microns. Ex: yeast
What are viruses?
Not in a kingdom, have no cells, a parasite of living cells.015-.1 microns. Ex: smallpox
Relative size of bacteria & viruses?
Limit of vision is 40 - 50 microns. WBC ~ 12-14 microns. RBC ~ 8 microns. Bacteria ~ 1 micron. Limit of light microsope magnification = .2 microns. Virus ~ .015 - .1 microns.
An AIDS patient develops extensive pneumonia and dies a week later. A sample of the lung fluid reveals 5-8 micron cells with a nucleus. The appearance of these cells means the organism is?
an unidentified eukaryote
The urine from a patient with pain under the ribs on the right and mild jaundice (yellow skin and eyes) reveals many long thin coiled cells, without a nucleus. These cells are _____, and he has leptospirosis
spirochetes
The sputum from a patient with difficulty breathing, a fever, fluid in the lungs seen on chest X-ray, and chest pain, reveals many round purple cells in pairs. The bacteria is a
Strep pneumoniae
A vaginal swab from a patient complaining of vaginal burning, itching, and a creamy discharge reveals many large (8-10 micron) oval cells with obvious nuclei. So you know
It can’t be bacteria, it could be yeast, it’s not HIV.
The swab of the throat of a college student with moderate swelling of obviously red tonsils, and many red spots on the soft tissue at the roof of the mouth, and little white abscesses on the tonsils, reveals many round purple cells in chains. A reasonable cause of this might be:
Streptococcus pyogenes
A 50 year old chain-smoking, alcoholic, diabetic, obese male develops an acute pneumonia. The cultures of sputum grow colonies of bacilli and the cells stain pink. They could be
Could be E.coli, klebsiella, Hemophilus, and Leginella
The Gram stained CSF from a [premature] neonatal patient with meningitis reveals small round purple cells in chains. The same bacteria was cultured from the cerebral-spinal fluid.
A reasonable cause of this infection might be
Group B Streptococcus
The amniotic fluid from a pregnant patient who just delivered a still-born infant reveals purple rods. You know it can’t be
Group B Streptococcus
The cervical swab of an 18 year old college student reveals round pink cells in groups of two. A reasonable cause of this might be _____, and she’s wrong when she asks ““it’s just a UTI, right?
Neisseria gonorrhea
The fluid draining from the ruptured eardrum of a 4 year old child reveals small, unpaired, oval-ish
pink cells. Being neither rods, nor spheres, they’re best described as
G- coccobacillus
An college student is seen in the clinic for a 2-month cough, weight loss, and night sweats. The sputum is thick, and sometimes tinged with blood. His sputum is stained a variety of ways, and one is designated ““AFB+””. What disease does he have (probably). ?
tuberculosis
The large blackened ulcer on the forearm of a soldier serving in Bloatedgoatistan reveals large, purple, square-ended rods in chains. The Gram’s stain is consistent with
Bacillus anthracis
A teenager complains of very stiff neck, fever, photosensitivity, vomiting and severe headache.
The CSF reveals a small number of white blood cells, but no other obvious cells.
Assume any cellular infectious agents would be visible. Which of these is incorrect?
the infection is probably due to bacteria less that .2 µM in size
An elderly patient with a post-surgical infection develops pus around the wound site and inflammation. The culture reveals round, G+ cocci in clusters. Which of these is correct?
he has a staph infection
The urine from a female complaining of burning, cloudy urine reveals pink rods. It’s likely to be
E. coli
The genital ulcer of a young adult is Gram stained, but no bacteria are visible. A silver stain reveals
numerous spirochetes, and a fluorescent antibody stain for Treponema is positive. She has?
syphilis
A college-aged female develops persistent vaginal irritation, and a greenish vaginal discharge.
Microscopic examination of a swabbed sample reveals pear shaped cells ~7x10 uM with a nucleus
and Trichomonas protozoa are presumptively identified . Which of the following is incorrect?
the infection could be treated with penicillin
A spherical bacteria that occur in clusters of 4 [and there are many G+ skin bacteria like this),
could be called which of these? (the names are fake!)
Quadracoccus
A rod-shaped bacteria that is multiply curved [but is not a spirochete] causes ulcers; it is?
Helicobacter
What is the cellular arrangement of Streptobacillus, the agent of ““rat-bite fever””? (a real disease)?
bacilli in chains
Bacteria isolated from a skin abscess are round, stain purple, and in clusters. It is?
Staphylococcus
A bacteria associated with an outbreak of ““food poisoning”” is rod-shaped, stains purple,
and does not form spores. Which one of these is it ? (all are associated with ““food poisoning””)
Listeria monocytogenes
Spore-forming anaerobes are found only the genus ___
Clostridium
An sample of food, associated with an outbreak of severe vomiting, grows a rod-shaped bacteria that forms spores, is aerobic, and stains purple. Which of these is it?
Bacillus cereus
A rod-shaped, pink-staining, bacteria isolated from a patient with dysentery is most likely to be…?
Shigella
Which of these is a reason that a Gram’s stain wouldn’t give a useful result?
Mycobacteria have thick waxy lipid layer
There are bacteria, called Buchnera, that grow inside the cells of some insects. They cannot grow on any agar media, and do not have cell walls. This site of growth resembles which bacteria? [Surprisingly, the aphids cannot live without them, as they supply essential amino acids to the insect].
Rickettsia
A patient with rapidly progressive paralysis is diagnosed with botulism.
What would the analysis of the suspected food reveal?
G+ rods
A patient is diagnosed with Chlamydia. What type of stain would allow the most specific
identification of the infectious agent?
flourescent Ab’s to Chlamydia
A unconscious patient with a grossly swollen lymph node in the armpit is brought to the Flagstaff hospital. He has a hemorrhagic rash and gangrenous fingers and toes. A lymph node sample obtained with a large needle biopsy reveals small G- rods. Wayson’s stain shows ““bi-polar staining””
A smear of the biopsy gives a positive result with anti-Yersina pestis fluorescent antibodies. The patient has:
bubonic plague
What is the difference between G + and G- between wall thickness?
G+ have 7-10 layer walls and G- have 1 layer.
What is the difference between G + and G- between membrane and location?
G+ have an inner membrane and G- have an outer membrane & an inner membrane
What characteristics do bacillus have?
G+ Aerobic rods with spores
What characteristics do clostridium have?
G+ Anaerobic rods with spores
Which bacteria cannot be gram stained?
Mycobacteria- too waxy outer layer, spirochetes - too thin, Rickettsia & Chlamydia obligate intracellular, and Mucoplasm Pneumonia - no cell wall.
What is the staining method for mycobacteria?
Acid Fast
What is a flourescent antibody and how specific is it?
The addition of a flourescent dye to an antibody, it is VERY specific.
What do Pilli do?
Attachement and/ or gene transfer
What do Flagella do?
Motility
What is capsule?
Protection against phagocytosis (antiphagocytic)
What are bacteial cell walls made of & what does it do?
Peptideoglycan structural integrity
What species have spores and how stable are they?
G+ aerobic and anerobic rods have spores Bacillus & Clostridium. They are very stable can withstand heat, radiation, and ehydration
Which of these bacterial structures can facilitate the penetration of the mucosal layer of the colon?
flagella
Sterilazation
Everything including the spores ae dead
Disinfectant
Almost everything except the spores are dead (even some are dead)
Sanitation
All the obvious stuff that would allow microbes to grow has been cleaned up.
What is pasteurization for & what does it kill?
Heating to 160 F does not kill spores
What is Auotoclaving, what does it kill, whats differnt from boiling?
Dry heat to 500 F, removes water so nothing can grow, kills everything sterilizes. Dry heat only works for things that wont melt wet heat can be used for food etc.
What are skin disinfectants & do they sterilize?
Iodine, alcohol, no they do not sterilize
Which of these is the common method to sterilize plastic medical supplies?
gamma radiation
Which of these is incorrect regarding bacterial cell walls?
G- cells have no cell wall - that’s why they’re ““negative””
Petri dishes that have been soaked in alcohol (prior to pouring fresh media) are:
not sterile
An autoclave is used to sterilize liquid microbiological growth media because it can
kill growing vegetative bacteria, protozoa, and fungi, inactivate non-growing cysts of protozoa and fungi spores, inactivate viruses
Which of these sanitation agents is also a very good disinfection agent?
amine detergents
The primary function of peptidoglycan is
to resist the osmotic pressure of the cytoplasm
Which of these are routinely sterilized by chlorination?
swimming pools
The ‘capsule’ of any bacteria is
a unique polysaccharide for each strain
The detergents used as a pre-surgical scrub usually contain the strong anti-microbial chemical
chlorhexidine
What is the primary use of iodine/detergent mixes in medicine?
preparation of skin prior to surgery
Which of these procedures is used to reduce or eliminate bacterial pathogen growth in foods.
drying, fermentation, pressure canning, cold storage
Which of these methods will not sterilize food?
pasteurization
"”Corned beef”” has nothing to do with corn. Beef is preserved by soaking in a barrel of strong brine.
Assuming the osmotic pressure in the brine is much higher than in the cytoplasm of the bacteria,
which of these will occur?
water leaves bacteria and enters brine
What method of sterilization is used for liquid drugs, protein solutions, and other injectable
(but heat-sensitive) liquids?
filtration to less than .1uM
A strain of Serratia is found in the CSF sample of a patient. The strain sticks tightly to meningeal cells.
The cell structure likely associated with this effect is:
pili
There are 5 different capsules produced by N. meningitidis. These capsules are composed of
secreted polysaccharides
The liquid inside a home-canned jar of pea soup is made anaerobic by boiling on the stove for 10
minutes. A ““pressure canner”” was not used. What did you just make?? (consider C. botulinum)
a selective media for anaerobes, a ““complex”” media,
a potentially fatal mistake
Which method of infection control would most reduce disease transmission in a hospital?
enforcing hand washing by all CNA’s, nurses, and especially doctors
Which of these is not a differential media?
a media that demonstrates bacterial motility; ie-motile bacteria form spreading colonies
Which of these would make a particular strain of bacteria more pathogenic?:
production of a secreted toxin, production of pili specific for some host tissue/cell, production of an antiphagocytic capsule
A media containing an antibiotic, that inhibits some bacterial species (but not others) is
selective
A motile bacteria that is also piliated, has a thick cell wall, produces a voluminous capsule,
and grows aerobically with the production of spores… could only be which one of these?
Bacillus
The most common example of an enriched medium in clinical bacteriology is:
media with added blood
A Group G strep strain forms tiny, but mucoid colonies. It commonly causes sepsis. It is non-motile,
non-piliated, and non-flagellated. The feature increase this strains pathogenic potential is:
a capsule
The initial step for the identification of any bacteria is:
Gram stain a sample
The most common use of selective media in the clinical lab is to
grow some species, but not others
A bacteria is isolated from a patient; on a variety of different plates incubated in air, you find:
it produces acid from lactose; produces H2S; and it is resistant to bile. From this you conclude:
the bacteria can grow aerobically, the bacteria is capable of anaerobic respiration, the bacteria can ferment lactose, the bacteria is likely enteric
A blood sample from a patient [with a fever of unknown origin] is streaked on a selective media. But after
incubation, nothing grew. When streaked on beef extract agar, large colonies appear.
Gram staining reveals small G- curved rods. From this you conclude:
you used the wrong selective media
A media for the growth of E. coli contains sorbitol as the sole carbon source, and ammonia/salts/metals [all
weighed and added separately]. Other enteric G- rods will not grow on the media. This medium is
selective, defined
A spirochete [isolated from a patient with arthritis] only grows at 2-4% oxygen, on pre-warmed blood agar.
It does not grow anaerobically, and does not produce acid or alcohol from various sugars.
Still, it only makes tiny colonies. Which of these is incorrect?
it is hemolytic
A catheterized patient develops a fever and turbid urine. Gram stain shows many G- rods, and WBC’s.
A streak of the urine on a beef extract agar [with glucose added and a pH sensitive dye] does not
produce acid, although it grows well in room air. There is no growth on anaerobic blood agar.
It grows aerobically on blood agar, and is hemolytic. Which of these is correct?
it’s not Clostridium, it lyses blood cells, it’s non-fermentative
The sputum sample from an intubated patient who has developed a fever and low oxygen saturation is streaked
onto a variety of differential, selective, and enriched media. It grows well on mannitol-salt agar, grows well on
beef extract agar, is hemolytic on blood agar, and does not grow on Gram negative bile-enteric agar. What is it?
Staph aureus
Hemophilus influenzae B requires the addition of specific amino acids, vitamins, NAD+, and heme
to beef extract agar to establish colonies. Even with all these additions to an already complex media,
it still only produces tiny colonies (1-2 mm). Alternatively, it will grow better on heated blood agar
where the blood cells have been burst by the heat ( it’s called ““chocolate agar””), or next to a hemolytic
Staph aureus colony on blood agar. From this data, you conclude the organism:
is fastidious
ATP Yeild
Fermentation = 2-3 ATP, Respiration = 10 - 20 ATP
What are common by-products of fermentation?
Acid & Alcohal
Enriched Media?
Complex media with something added (blood, soy, etc) good for fastideous organisms
Selective Media?
Complex media with chemical added that selescts for growth of particular bacteria (i.e. selects for staph).
Differential Media?
Allows you to tell the differenece between some bacteria. (some ferment others don’t)
MacConkeys Media?
Both Differential & selective. For G- Enterics. Crystal Violet inhibits growth of G+ (selesction) and fermentation for diff.
Manitol Salt Media?
Both Differential & selective. For Staph. Salt for selection. Ph dye for fermentation - diff.
What is the mutation rate for bacteria?
1 X 10^7 or 1 in 10 million
What is a plasmid?
A small circular mini- chromosome that codes for ABX resistance. Can be trasfered from on cell to another (conjugation)
What are the most clinically important genes that are on plasmids?
Antibiotic reisstnace & toxin production
How does resistance to a single ABX develope out of the blue?
By replication error
How do bacteria become resistant to many ABX in a single setp?
By plasmid transfer
What does ABX resistance gene on a plasmid code for?
Enzyme- (the enzyme inactivates the abx)
What is B-Lactamase?
Hydrolyse (inactivate) B-Lactam ring. Some are penicillinase and others are cephalosporinase.
What is ESBL & What abx does it effect?
ESBL = Extended Spectrum Beta Lactamase. It effects B-lactams.
What is the target of almost all drugs, including abx?
Enzymes
What is the most unique target in bacteria (eukaryotes, protozoa, & fungi don’t have them)
Peptidoglycan cell walls
What is the difference between bacteriostatic and bacteriocidal?
Bacteriocidal = kills and Bacteriostatic = inhibits growth
What is prophylaxis?
RX prior to infection. Used for TB, Plague, STD’s. # 1 ABX neosporin
What does MIC stand for & what does it depend on?
MIC = Minimal Inhibitory concentraition. Depends on the drug and the bug.
What is the difference between broad spectrum & narrow spectrum abx?
Broad = affect lg. range of bacteria & commonly normal flora (diarrhea # 1 side effect). Narrow = Their use requires the specific pathogen be identified.
What is the difference between a penicillin resistant bacteria & penicillinase resistant abx? What are pcn-ase ^R abx that have replaced methicillin?
PCN^R bacteria inhibit pcn. PCN-ase^ R abx inhibit penicillinase allowing the abx to work on bacteria. pnc-ase ^R abx that have replaced methicillin = Oxacillin, Cloxa “” “”, Diclox”” “”, Naficillin.
What is a urinary antiseptic?
An abx used to treat UTI (nitrofurantoin)
Does a mixture of trimethoprim/ sulfa act synergistically if so Whay?
Yes, both are folate synthesis inhibitors.
Are sulfa’s bacteriostatic or bactericidal?
Bacteriostatic
What are the 2 most common side effects of abx?
1 diarrhea # 2 transient rash
Which abx commonly have serious kidney impairment?
Vancomycin & Aminoglycosides
What is a ““super infection”” after treatment with broad spectrum abx?
"”Overgrowth”” most commonly yeast infection.
What abx is used tpo treat abcesses & anaerobic infections?
Clindamycin
What is the relationship between clindamycin & C-diff pseudomomembranous colitis?
Invalid- colonized w/ C diff- pressure sore- mixed aerob & anerobic infection - treat w clindamycine- C diff overgrows- eventual death
What is rifampin commonly used to treat other than TB?
Leprosy w/ dapsene
Why is benzathine pcn sufficient to treat syphilis & what is unusual about it?
Poorly soluable, I. M. only, long half life.
I.M. bnz-pcn used for rhumatic fever. What is prophhylaxis?
RX prior to infection.
Which pcn’s are used to treat MSSA infections? Why not amoxicillin or pcn G?
Methicillin, naficillin, etc. Because pcn G and amox are IV only with short half life.
Which cell wall synthesis inhibitor is used if the staph is MRSA istead of MSSA?
Vancomycin
What is an ““AP-PCN”” & what bacteria are these abx used for?
Anti Pseudomonas PCN. Pipericillin & tiraricillin. pneumonia
What is an ““AP-AG”” and what bacteria are these abx used for?
Anti Pseudomonas Amino Glycoside. Tobramycin, for pseudomons & MRSA
What effect does tazobactam or clavulanate have on the beta-lactamase enzyme?
They inactivate the enzyme allowing the abx to kill or inhibit the bacteria.
What are tazobactam and clavulanate combined with and why?
They are combined with pcn-ase ^S B-lactams so they can inhibit the bacteria. They arensynergistic.
Which bacteria are the 1st, 2nd, 3rd, and 4th generation cepholosporins used for?
Penicillin^R bacteria
Why are FQ’s not used for meningitis?
Because they do not cross the BBB
What infections require immidiate anti-toxins?
tetanus, botulism, and diphtheria
What does anti-toxin consist of?
a injection of gamma-globulin antibodies to the suspected infection/toxin.
What are the anatomic sies that are difficult to treat?
The toxin binds to, and inactivates, the toxin
The term ““antibiotics”” generally refers to:
antibacterial drug
Which of the these is not an antibiotic target?
capsule synthesis
Which of these drugs targets the cell wall synthesis enzymes of bacteria?
cephalexin
Which of these drugs inhibits the action of ribosomes?
tertacycline, erythromycin, & gentomycin
Which of these drugs targets the synthesis of messenger RNA?
rifampin
Which of these drugs does not target the synthesis of folic acid?
streptomycin
Which of these drugs does not target DNA winding/unwinding enzymes?
clindamycin
Which of these drugs targets the bacterial cytoplasmic membrane?
polymyxin
Abx that cause the death of bacterial cells are called
bactericidal
If a strain of bacteria produces penicillinase, the strain is :
penicillinR
Abx that inhibit the growth of bacteria, but do not directly kill them are:
bacteristatic
Which of these drugs has a beta-lactam chemical structure, but does not inhibit cell wall synthesis
clavulanic acid
What do you call a penicillin that is not inactivated by penicillinase?
pcn-aseR abx
An abx that is rapidly excreted in the urine, in an active concentration, would be useful to treat
UTI’s
Which of these is a penicillinase resistant penicillin?
oxacillin
Which of these is a non-ß-lactam cell wall synthesis inhibitor (commonly used to treat MRSA)?
vancomycin
Dirtomyces pauli is found to produce a beta-lactam compound that inhibits carbapenemase.
It has no inhibitory activity to bacteria. Which of these would it be combined with?
ertapenem
A new drug that is very similar in structure to para-aminobenzoic acid is probably related to:
sulfonamide
ß-lactamase is an enzyme. What does it do?
inactivates ß-lactam abx’s
A new drug is structurally similar to clarithromycin. It’s probably an inhibitor of
ribosomes
Assume a Staph strain is resistant to all ß-lactam abx.
What cell wall synthesis inhibitor might still work?
vancomycin
Which of these would be used to treat acne (an anaerobic skin infection) and Giardia,
an anaerobic protozoa that infects the intestines and causes [really foul] diarrhea?
Flagyl
What is the approximate chance of bacteria acquiring 2 abx resistances simultaneously?
1 x 10^14
You grow a single tube of bacteria (in the absence of antibiotics) to a cell concentration of
>109 bacteria/ml. You then put >108 bacteria (.1 ml) on each of 5 different agar plates.
Each plate has a different antibiotic [A, B, C, D, E, or F]. What will you find tomorrow?
each plate will have ~10 colonies that are resistant only to the abx in that plate
