Removal exam Flashcards
The layer just outside the bacterial cytoplasmic membrane
peptidoglycan layer
Composed of repeating disaccharides with 4 amino acids in a side chain extending from each disaccharide
peptidoglycan layer
The enzyme that catalyzes the formation of this linkage
transpeptidase
The antibiotic penicillin binds to and inhibits this enzyme. For this reason the enzyme is
also called _________
penicillin binding protein
Very thick and has extensive cross-linking of the amino-acid side chains
gram-positive cell wall
has S layers, not including the periplasmic space.
gram-negative cell envelope
contains a phospholipid bilayer with embedded proteins
inner cytoplasmic membrane
filled with a gel that contains proteins and enzymes.
periplasmic space
The thin peptidoglycan layer does not contain teichoic acid, although it does have a small helical lipoprotein
murein lipoprotein.
,which is a disaccharide with multiple fatty acid tails reaching into the membrane.
lipid A
toxic to humans and is known as the gram-negative
endotoxin.
lipid A
Embedded in the gram-negative outer membrane, which allow passage of nutrients. These are also unique to gram-negative organism.
porin proteins,
spherical
Cocci
rods.
Bacilli
Short bacilli
coccobacilli.
comma-shaped, S-shaped, or spiral-shaped.
Spiral forms
lacking a distinct shape (like jello)
Pleomorphic
forms strips of cocci
Streptococcus
forms clusters of cocci.
Staphylococcus
Two of the 4 gram-positive rods produce
spores
spheres that protect a dormant bacterium from the
harsh environment
spores
which causes syphilis.
Treponema pallidum
It is actually a diplococcus (looks like 2 coffee beans kissing):
Neisseria
are weakly gram-positive but stain better with a special stain called the acid-fast stain
Mycobacteria
have a gram-negative cell wall but are too small to be seen with the light microscope and so must be visualized with a special darkfield microscope
Spirochetes
Spirochetes have a gram-negative cell wall but are too small to be seen with the light microscope and so must be visualized with a special __________.
darkfield microscope.
do not have a cell wall. They only have a simple cell membrane, so they are neither gram positive nor gram-negative.
Mycoplasma
usually consists of a single circle of double-stranded DNA
Bacterial DNA
are composed of protein and RNA and are involved in the translation process, during the synthesis of proteins.
Ribosomes
have smaller ribosomes (70S) than animals (80S), which are eucaryotes.
Bacterial ribosomes consist of 2 subunits, a large subunit (50S) and a small subunit (30S).
procaryotes,
which surprisingly has endotoxin-surprising because ALL other organisms with endotoxin are gram-negative.
Listeria
breaks down hydrogen peroxide in the following reaction
Catalase
also breaks down hydrogen peroxide
Peroxidase
These critters are just like us
in that they use glycolysis, the Krebs TCA cycle, and the
electron transport chain with oxygen as the final electron acceptor. These guys have all the above enzymes.
Obligate aerobes
Don’t let this name fool you! These bacteria are aerobic. They use oxygen as an
electron acceptor in their electron transfer chain and have catalase and superoxide dismustase.
Facultative anaerobes:
The only difference is that they can grow in the absence of oxygen by using fermentation for energy
Facultative anaerobes:
These bacteria use fermentation and have no electron transport system. They can tolerate low amounts of oxygen because they have superoxide dismustase (but they have no catalase).
Microaerophilic bacteria (also called aerotolerant anaerobes)
These guys hate oxygen and have no enzymes to defend against it. When you are
working on the hospital ward, you will often draw blood for culture.
Obligate anaerobes
Of the organisms that use chemical sources, those that use inorganic sources, such
as ammonium and sulfide, are called a ___________.
autotrophs
use organic carbon sources and are called _________
heterotrophs.
used by many bacteria for oxygen metabolism.
Fermentation (glycolysis)
broken down to pyruvic acid, yielding ATP directly
Glucose
There are different pathways for the breakdown of glucose to pyruvate, but the most common
Embden Meyerhof pathway
This is the pathway of glycolysis that we have all studied in biochemistry
Embden Meyerhof pathway
used with the aerobic and facultative anaerobic organisms.
Respiration
are not capable of the metabolic pathways for ATP synthesis and thus must steal ATP from their host.
Obligate intracellular organisms
These bacteria live in their host cell and cannot survive without the host.
Obligate intracellular organisms
those that can cause disease.
Virulent organisms
the degree of organism pathogenicity.
virulence of an organism
depends on the presence of certain cell structures and on bacterial exotoxins and endotoxins, all of which are virulence factors.
Virulence
are protein filaments that extend like long tails from the cell membranes of certain gram positive and gram-negative bacteria.
Flagella
affixed to the bacteria by a basal body.
Flagellum
does not have flagella.
Shigella
are straight filaments arising from the bacterial cell wall, making the bacterium look like a porcupine.
Pili (also called fimbriae)
Pili can serve as adherence factors (in which case they are called _______
adhesins
uses its adhesin to bind to ciliated respiratory cells and cause whooping cough.
Bordetella pertussis
has pili that allow it to bind to cervical cells and buccal cells to cause gonorrhea
Neisseria gonorrhea
are protective walls that surround the cell membranes of gram-positive and gram-negative bacteria.
Capsules
They are usually composed of simple sugar residues. Bacteria secrete these sugar moieties, which then coat their outer wall.
Capsules
unique in that its capsule is made up of amino acid residues.
Bacillus anthracis
Because this stain is not taken up by the capsule, the capsule appears as a transparent halo around the cell.
India ink stain
This test is used primarily to identify the fungus Cryptococcus.
India ink stain
The bacteria are mixed with antibodies that bind to the capsule. When these antibodies bind, the capsule swells with water, and this can be visualized microscopically
Quellung reaction
The process of antibodies binding to the capsule
opsonization
are formed by only 2 genera of bacteria, both of which are gram-positive
Endospores
metabolically dormant forms of bacteria that are resistant to heat (boiling),
cold, drying and chemical agents
Endospores
An outer layer called _______.
exosporium
Many bacteria are phagocytosed by the host’s macrophages and neutrophils yet survive within these white blood cells unharmed.
Facultative Intracellular Organisms
proteins that are released by both gram-positive and gram-negative bacteria. They may cause many disease manifestations.
Exotoxins
produces endotoxin
Listeria monocytogenes
exotoxins that act on the gastrointestinal (GI) tract to cause diarrhea. Inhibit NaCl resorption, activate NaCl secretion, or kill intestinal epithelial cells
Enterotoxin
Bacteria colonize and bind to the GI tract, continuously releasing their enterotoxins locally.
Infectious diarrhea
The diarrhea will continue until the bacteria are destroyed by the immune system or antibiotics (or the patient dies secondary to dehydration)
Infectious diarrhea
Bacteria grow in food and release enterotoxin in the food. The enterotoxin is ingested resulting in diarrhea and vomiting for less than 24 hours.
Food poisoning
stimulate the release of cytokines and can cause rash, fever, and toxic shock syndrome
Pyrogenic exotoxins
allow bacteria to destroy and tunnel through tissues. These include enzymes that destroy DNA, collagen, fibrin, NAD, red blood cells, and white blood cells.
Tissue invasive exotoxins
which are the principle virulence factors for many bacteria, can cause disease
unique to the individual bacterium. Often the exact roleof the exotoxin is poorly understood
Miscellaneous exotoxins
is a common and deadly response to both gram-negative and gram positive infection
Septic shock
the number one cause of death in intensive care units and the 13th
most common cause of death in the U.S.
Septic shock
This is simply bacteria in the bloodstream
Bacteremia
Sepsis that results in dangerous drops in blood pressure and organ dysfunction
Septic shock
endotoxin often triggers the immune response that results in sepsis and shock
endotoxic shock
These cells, in response to the stimulus, release a host of proteins that are referred to a _________
endogenous mediators
The most famous endogenous mediator of sepsis.
tumor necrosis factor (TNF).
TNF is called ________.
cachectin
double-stranded DNA molecule that is closed in a giant loop.
bacterial chromosome
Transduction occurs when a virus that infects bacteria, called ________, carries a piece of bacterial DNA from one bacterium to another
bacteriophage
infecting the bacteria, reproducing, and then lysing and killing the bacteria
Virulent phages
have a good temperament and do not immediately lyse the bacteria they infect
temperate phages
The integrated temperate phage genome
prophage
Bacteria that have a prophage integrated into their chromosome, because at some time the repressed prophage can become activated.
lysogenic
the term used to describe the ability of an integrated bacteriophage (prophage) to block a subsequent infection by a similar phage
Lysogenic immunity
these phages can carry bacterial DNA from one bacterium to another. This process is called _______.
transduction
occurs with phage lambda in Escherichia coli. The site of insertion of the lambda prophage lies between the Escherichia coli gene for biotin synthesis and galactose synthesis.
Specialized transduction
the gene for biotin synthesis can now be transferred to another bacteria that does not have that capability. You will frequently hear about this form of gene acquisition; it is called ___________.
lysogenic conversion
For conjugation to occur, one bacterium must have a self-transmissible plasmid
F plasmid
The self-transmissible plasmid (F plasmid) has a gene that encodes enzymes and proteins that form
the sex penis,
sex pilus
the extra-chromosomal F plasmid becomes integrated in the neighboring bacterial chromosome much in the same way as a temperate bacteriophage does. The bacterial cell is then called _________.
Hfr cell
High frequency of chromosomal recombinants. This integration can result in two unique mechanisms
of DNA transfer
Hfr cell
are both gram-positive spheres (cocci) and are responsible for a wide variety of clinical diseases
Streptococci and staphylococci
A second method to differentiate streptococci from staphylococci involves the enzyme
catalase
incubated overnight on a blood agar plate. B
streptococci
Completely lyse the RBCs, leaving a clear zone of
hemolysis around the colony.
Beta-hemolytic streptococci
only partially lyse the RBCs, leaving a greenish discoloration of the culture medium surrounding the
colony.
Alpha-hemolytic streptococci
are unable to hemolyze the RBCs, and therefore we should really not use the word “hemolytic” in this situation
Gammahemolytic streptococci
Used as a major way of differentiating the many streptococci.
Lancefield antigens
These organisms are so-named because they possess the Lancefeld group A antigen and are beta-hemolytic on blood agar.
GROUP A BETA-HEMOLYTIC STREPTOCOCCI (also called Streptococcus pyogenes)
which (means pus-producing) and cause the diseases “strep throat,” scarlet fever, rheumatic fever, and post-streptococcal glomerulonephritis
Streptococcus pyogenes
used by Rebecca Lancefield to divide streptococci into groups.
C carbohydrate
C carbohydrates was used by _______
Rebecca Lancefield
This is a major virulence factor for the group A streptococcus.
M protein
It inhibits the activation of complement and protects the organism from phagocytosis. However, it is also the weakest point in the organism’s defense, because plasma (B) cells generate antibodies
against the M protein.
M protein
The stands for oxygen labile as it is inactivated by oxygen.
Streptolysin O
This enzyme destroys red and white blood cells and is the reason for the beta-hemolytic
group A streptococci’s beta-hemolytic ability
Streptolysin O
The stands for oxygen stabile. This is also responsible for beta-hemolysis but is not antigenic.
Streptolysin S
This is found in only a few strains of betahemolytic group A streptococci, but when these strains invade they can cause scarlet fever.
Pyrogenic exotoxin (also called erythrogenic toxin)
activates the proteolytic enzyme plasmin, which breaks up fibrin blood clots
streptokinase
This is the classic strep throat with red swollen tonsils and pharynx, a purulent exudate on the tonsils, high temperature, and swollen lymph nodes. It usually lasts 5 days (penicillin therapy speeds recovery)
Streptococcal pharyngitis
can range from folliculitis (infections of the hair follicles), cellulitis (a deep infection of the skin cells, producing red, swollen skin which is hot to the touch), and impetigo (a vesicular, blistered, eruption, most common in children, that becomes crusty and flaky and is frequently found
around the mouth)
Skin infections
(“Flesh-eating Streptococcus”)
Necrotizing Fasciitis
This type of group A beta-hemolytic streptococcal infection has actually been around for years but may indeed be on the rise (news coverage certainly is).
Necrotizing Fasciitis
gram-negative enterics, or mixed infection with more than one of these bacteria
Clostridium species
Certain beta-hemolytic group A streptococci not only cause a sore throat
Scarlet fever
Certain beta-hemolytic group A streptococci not only cause a sore throat, but also produce an exotoxin called _________.
pyrogenic toxin or erythrogenic toxin
It is now clear that beta-hemolytic group A streptococci can cause toxic shock syndrome like that caused by Staphylococcus aureus
Streptococcal toxic shock syndrome
With the advent of penicillin, is now uncommon. It usually strikes children 5-15 years of age
Rheumatic fever
Rash, because it has a red margin that spreads out from its center.
erythema marginatum
Picture John Travolta in the movie Rheumatic Fever, the upcoming sequel to _______.
Saturday Night Fever
This is an antibody-mediated inflammatory disease of the glomeruli of the kidney
Acute post-streptococcal glomerulonephritis
causes tea colored urine (hematuria).
Acute post-streptococcal glomerulonephritis
About 25% of women carry these bugs vaginally, and a baby can acquire these bacteria during delivery. These organisms cause neonatal (< 3 months of age) meningitis, pneumonia, and sepsis.
GROUP B STREPTOCOCCI
alpha-hemolytic, producing greenish discoloration on blood agar
viridans streptococci
Some of the viridans streptococci, especially S. mutans, can bind to teeth and ferment sugar, which produces acid and dental caries ( cavities!!).
Dental infections
Dental manipulations send showers of these organisms into the bloodstream. Subsequently, they can implant on the endocardial surface of the heart, most commonly on a previously damaged heart valve (such as from old rheumatic fever, a congenital heart defect, or mitral valve prolapse)
Endocarditis
eating heart valves slowly
Viridans Streptococcus
There is a subgroup of the viridans streptococci, which are microaerophilic and are part of the normal G.I. tract flora.
Streptococcus intermedius group
comprised of Enterococcus faecalis and Enterococcus faecium
enterococci
comprised of many organisms including Streptococcus bovis and Streptococcus equinus)
non-enterococci
Traditionally these alpha-hemolytic bacteria have been divided into two subgroups
GROUP D STREPTOCOCCI
hardy, growing in 40% bile (but not in 6.5% NaCl). It lives in the G.I. tract, and it causes similar diseases
Streptococcus bovis
A very important organism because it is a major cause of bacterial pneumonia and meningitis in adults, and otitis media in children. pneumococcus is to parents what group B streptococcus is to
Babies
Streptococcus pneumoniae
When pneumococci on a slide smear are mixed with a small amount of antiserum (serum with antibodies to the capsular antigens) and methylene blue, the capsule will appear to swell
Quellung reaction
This technique allows for rapid identification of this organism
Quellung reaction
is the most common cause of pneumonia in adults.
Streptococcus pneumoniae
