Bacteria Flashcards
Staphylococcal species is gram___ and____
gram positive and aerobic
Streptococcal species is gram ___ and ____
gram positive and aerobic
Enterococcal species is gram___ and ____
gram positive and aerobic
What is the most virulent of the staph species?
staph aureus
staph aureus is coagulase ____
positive
Most staph aureus produce _____, mediated by plasmids
penicillinase (beta-lactamase)
What is affective against staph aureus?
penicillinase-resistant penicillin (methicillin) and cephalosporins
What is methicillin-resistant, cephalosporin resistant, but vancomycin sensitive?
MRSA - chromosomally encoded PBP (penicillin binding protein)
VISA stands for
vancomycin intermediately susceptable
GISA stands for
glycopeptide intermediately susceptable
Staph aureus is a true _____
pathogen
Staph aureus is gram ____
positive
Staph epidermidis is gram ____
positive
Which staph is part of the normal skin flora?
staph epidermidis
staph epi. is coagulase ____
negative
Which staph is usually a colonizer?
staph epi
Diseases from staph ____ are usually associated with immunocompromised, violation of natural barriers, implantation of foreign devices (biofilms)
staph epi
Coagulase positive test means it is ___ form
gel
coagulase negative test means it is ____ form
liquid
Staph saprophyticus is gram ___
positive
staph sapro is coagulase ___
negative
Which staph species rarely causes infection in healthy individuals, but is most noted for UTI’s in women?
staph saprophyticus
Pyogenic supprative lesions, infection of the hair follicle or sweat gland, acne vulgaris, or a stye are all considered
furunculosis (“boil”)
infection of the base of the eyelash
stye
Spreading lesions of subq tissue, very serious, can lead to bloodstream infection is known as
carbuncle
Highly communicable, superficial skin infection, large blisters containing viable staph, seen mostly in infants and children under conditions where infections can easily be spread through touch contamination is known as
bullous impetigo
infection of soft tissue around the nails is known as
paronychia
tissue destruction with abscess formation in deep tissues is known as
deep lesions
Examples of deep tissue infections are:
osteomyelitis, septic arthritis, cerebral, pulmonary and renal abscesses, breast abscesses, bacterial pneumonia, endocarditis, entercolitis
In individuals with diabetes, alcoholism, malignancy, old age, steroid or cytotoxic therapy have an increased risk to having
deep lesions
when bacteria gets in the blood causing severe infections it is known as
septicemia
Gangrene is a type of
staph septicemia
Diseases can be caused by staphylococcal ____
toxins
Staphylococal toxins can cause diseases such as:
scalded skin syndrome (Ritter’s Disease)
Toxic Shock Syndrome
Staphylococcal food poisioning
streptococcus is gram ___
positive
Streptococcus is ____ or ___ shaped
spherical or oval
Streptococcus is usually found in ____ or ___
chains or pairs
Which bacteria comprise significant portion of the indigenous microflora of humans and animals (mostly GI tract; some respiratory tract)?
streptococcus (rarely cause disease)
Streptococcus has 3 impt human pathogens, they are:
strep pyogenes
strep pneumoniae
strep agalactiae
A further classification of the streptococcus species is
Lancefield groups
Lancefield groups are based on
antigenic characteristics of the outer membrane
There are ___ common groups designated by the letters of the alphabet (A-R) for Lancefield groups
14
Another classification of strep species is ____
brown groups
For brown group classification, streptococci are grown on sheep’s blood agar producing 3 pathogens of _____ around the colonies
hemolysis
A green zone is ___ hemolysis and is indicative of _____ hemolysis
alpha, incomplete
What are the two strep species that have alpha hemolysis?
S. pneumoniae, s. viridans
A clear zone is ___ hemolysis and is indicative of ____ hemolysis
beta, complete
What are two strep species that have beta hemolysis?
s. pyogenes, s. agalactiae
No zone is ___ hemolysis and is indicative of _______
gamma, non-hemolytic
What group of streptococci are non-hemolytic?
most Group D
Clinical classification combines ___ and ___ groupings and disease producing characterisitcs
Lancefield and Brown
An example of clinical classification for s. pyogenes would be
Group A, beta hemolytic Strep
Enterococcal and Non-enterococcal species are both
Group D Streptococci
A sore throat is
pharyngitis
Pharyngitis accounts for ___ million MD office visits yearly
40
Of all the sore throats presented, many of them are actually caused by
viruses
Only ___ of sore throats are caused from Group __ Streptococcus
15%, group A
Pharyngitis can also be caused by:
Arcanobacterium hemolyticum, neisseria gonorrhea, chlamydia pneumoniae, epstein-barr virus (mononucleosis), & other viruses
When a patient presents with pharyngitis, the diagnostic focus is to rule in or out ____
group A strep
First test to perform in a patient with pharyngitis is
rapid strep test
In a rapid strep test, good specificity (90%), means if the test is positive, ___ chance that a strep infection __ occuring
90% chance it IS occuring
In a rapid strep test, fair specificity (60%), means if the test is negative, ____ chance that you ____a strep infection
40% chance you MISSED a strep infection
What is the gold standard for someone with pharyngitis?
Culture and susceptibility of throat swab
If the rapid strep test is negative, the next step is to
perform a throat culture
Pharyngitis is usually indistinguishable from
viral infections
If a patient with pharyngitis turns out to have group ___, ____-hemolytic strep, concern arises over immunological sequella (disease that can result from pharyngitis)
group A, beta-hemolytic
Sequellas that can arise from group A, beta-hemolytic strep are:
Rheumatic fever (heart valve disease) - more common with strep pharyngitis Acute glomerulnephritis (chronic renal failure) - more common with strep impetigo
Another strep disease causing a localized infection of healthy skin is
impetigo
Impetigo usually affects kids ___ years old
2-5
Vesicles associated with impetigo are ____, but lesions do not usually result in ____
contagious, scarring
In a patient with impetigo, staph ___ sometimes becomes a secondary invader
staph aureus
Nephritogenic strains of imetigo cause immunogloblins to
attack the kidneys
Another strep disease that causes strep infection of the skin and subcutaneous tissues (dermis) is
erysipelas
Spreading areas of erythema and pain with systemic manifestations of fever and lymphadenopathy is associated with
erysipelas
Patients with erysipelas usually have a history of a ____ and the infection is usually on the ___
sore throat, face
Serious infection of ____ can require ____ (PCN)
erysipelas, antibiotics (penicillin)
Cellulitis, necrotizing fasciitis (“flesh-eating strep”), would and burn infections, puerperal infection, scarlet fever, immunologic sequelae (rheumatic fever, acute glomerulonephritis) are all examples of
streptococcal diseases
Strep agalactiae is classified as a group ___ strep
B
The species responsible for the leading cause of pneumonia, sepsis and meningitis during the first 2 mos of life is
strep agalactiae
strep agalactiae has an incidence of ___ cases per ____ births
1-3/1000 births
Mortality rates from strep agalactiae ___ to __
30-60%
immediate perinatal period infections caused by contamination of infant with birth canal is from
strep agalactiae
_____ is a late onset disease (3-8 wks post-partum lower mortality rate (not enough maternal IgG)
strep agalactiae
Treatment for step agalactiae is
penicillin and aminoglycoside
Streptococcus pneumoniae aka “pneumococcus” or “diplococcus” has no
Lancefield classification
strep pneumoniae has a unique ____ which inhibits ____
polysaccharide capsule, phagocytosis
-at least 80 antigenically distinct types
Many strains of strep pneumoniae are sensitive to ___ but growing numbers are becoming resistant
penicillin
Strep pneumoniae is responsible for causing
community acquired pneumonia
The most common cause of bacterial pneumonia is
pneumococcal pneumonia
Mortality from pneumococcal pneumonia increases dramatically after ___ yrs of age
50
alcoholism, diabetes mellitus, chronic renal disease, some malignancies, transplantation all increase mortality from
pneumonia
Treatment for ___ is getting more complicated
pneumococcal pneumonia
pneumococcal meningitis is caused by the bacteria
strep pneumoniae
strep pneumonia is one of the “big three” causes of ___ and the most common
bacterial meningitis
Neisseria meningiditis causes
meningococcal meningitis
H. influenzae is caused by the bacteria
haemophilus influenzae
common cause of sinusitis and otitis media is
upper respiratory infection (URI)
Other infections caused by _____ include: endocarditis, arthritis and peritonitis usually following bloodstream infections
strep pneumoniae
when treating a patient with strep pneumoniae you must consider
site of infection
meningitis vs. pneumonia vs. bacteremia vs. URI
For CNS infections,
Drug-susceptible strep pneumoniae (DSSP)
-penicillin G (MIC is less/equal to ___mcg/mL)
Drug-intermediate susceptible strep pneumoniae
-MIC greater/equal to ___
DSSP 0.06mcg/mL
DISSP 0.12
DRSP 2.0
For lung and intestinal fluid,
susceptible less/equal to
intermediate equal
resistant greater than
2
4
8
High risk patients for strep pneumoniae are elderly older than ___ and those with ____ affecting immune status
65, underlying diseases
2 vacinne types for strep pneumoniae
pneumococcal conjugate vaccine, 7 valent
pneumococcal polysaccharide vaccine, 23 valent
7 valent vaccine covers ____ of disease causing strains.
80%
23 valent vaccine covers ____ of disease causing strains
98%
Prevnar (7 valent) is for children less than ___ yrs of age
2
pneumovax 23, pneu-imune 23 are for children older than ___ yrs of age and
2 and high risk adults
The spleen is composed of ___ pulp, ___ pulp, ___follicles, and ____sheaths
red, white, lymphoid, periarteriolar lymphoid
mechanical filtration of the red blood cells
red pulp
provides active immune response through humoral and cell-mediated pathways
white pulp
rich in B-lymphocytes
lymphoid follicles
rich in t-lymphocytes
periarteriolar lymphoid sheaths
A large group of streptococci with no ____ designation but with ___ hemolytic characteristic and are major constituents of the mouth and nasopharnyx are Viridans
lancefield, alpha
subacute bacterial endocarditis is caused by
viridans group A strep
Enterococcus is ___ hemolysis
gamma
Normal inhabitants of GI tract and able to survive harsh condition are
enterococcus
enterococcus can spread through
touch contamination
enterococcus can be very resistant to
penicillin and others
Many times, this bacteria must be treated with a combination of antibiotics (synergy)
enterococcus
Enterococcus does NOT cause
pneumonia
Opportunistic organisms capable of causing UTI’s, wound infections, endocarditis in damaged heart valves are
enterococcus species
One of the most highly resistant organisms today
enterococcus
synergistic combos are losing effectiveness
VRE stands for
Vancomycin resistant entercoccus
enterococcus faecium
There is some evidence that the resistance factors can be passed on to more virulent organisms such as
staph aureus
Molecular _____ is very reactive and toxic
oxygen
what are the 3 forms of molecular oxygen?
H2O2 (peroxide)
O2- (superoxide radicals)
OH- (hydroxyl radicals)
____ pour oxygen radicals over bacteria
macrophages
There are ___ bacterial enzymes that break down oxygen radicals. What are they?
3
Catalase
peroxidase
superoxidase dismutase
catalase reaction
2(H2O2) –> 2(H2O) + O2
peroxidase reaction
2(H2O2) –> 2(H2O) + O2
