micro- Gram + bacteria Flashcards
1
Q
how do you differentiate between staph and strep cocci
A
catalse test
streptococcal infections are catalase -
or look at grouping of gram stain
2
Q
Differentiate beta and alpha hemolytic strep
A
beta completely lyse RBC leaving clear zone of hemolysis around the colony
alpha partially lyse RBC leaving greenish coloration
3
Q
What is the molecule that is green after adding alpha hemolytic strep to blood agar plate
A
metabolite of Hb
4
Q
what is the third type of hemolytic strep
A
gamma
cannot hemolyze RBC
5
Q
What are the Lancefield Ag on strep
A
C carbohydrates classified as A B C DE thru S
6
Q
What are the 5 human significant strep infections
A
A B D
strep pneumoniae
viridans group
7
Q
What is another name for group A beta hemolytic strep
A
streptococcus pyogenes
8
Q
What diseases is strep pyogenes responsible for
A
scarlet fever, rheumatic fever, post streptococcal glomerulonephritis
9
Q
What are the antigenic properties found on strep pyogenes
A
C carbohydrate
M protein
10
Q
What is the role of the M protein of strep pyogenes
A
inhibits activation of C’ and protects organism from phagocytosis
11
Q
What is the bodys response to M protein of strep pyogenes
A
B cells generate Ab against M protein
12
Q
What enzyme is responsible for the hemolytic ability of strep pyogenes
A
streptolysin O
13
Q
What type of titers do you take on a patient to confirm past strep pyogenes infection
A
anti-streptolysin O
ASO titers
14
Q
What other toxins does strep pyogenes produce
A
Streptolysin S aids in hemolysis pyrogenic exotoxin on some streptokinases hyaluronidase DNAase anti C5a-peptidase
15
Q
What are the 4 types of disease that strep pyogenes causes in local invasion or exotoxin release
A
strep pharyngitis
strep skin infections
scarlet fever
strep TSS
16
Q
What type of reactions/diseases are rheumatic fever and glomerulonephritis caused by strep pyogenes
A
delayed Ab mediated diseases
17
Q
What is the presentation of strep pharyngitis
A
strep throat with red swollen tonsils and pharynx with purulent exudate on tonsils and high temp with swollen lymph nodes
18
Q
What test should you order if you suspect strep throat
A
rapid antigen detection test RADT detecting the group A carb Ag
19
Q
With a - RADT test in a child you suspect strep in what else should be done
A
throat culture
20
Q
what type of skin infections can be caused by strep pyogenes
A
folliculitis, pyoderma,erysipelas, cellulitis, impetigo
21
Q
What is impetigo
A
vesicular blistered eruption that becomes crusty and flaky
22
Q
what is erysipelas
A
bright red rash with sharp border that advances from initial infection site
23
Q
what is pyoderma
A
pustule on extremity or face that breaks down after 4-6 days to form a crust and leave depigmented area
24
Q
What is a worrysome complication of skin infections from strep pyogenes
A
necrotizing fascitis
25
what is fourniers gangrene
necrotizing fasciitis involving male genitale area and perineum
26
The pyrogenic toxin or erythrogenic toxin of s pyrogenes can lead to what
scarlet fever
27
what does the rash of scarlet fever appear like
red that begins on trunk and neck spreads to extremities but spares face
28
what are risk factors for rheumatic fever
had recent strep pharyngitis
| age 5-15
29
What are the manifestations of rheumatic fever
fever, myocarditis, arthritis, chorea, subcut nodules, rash "erythema marginatum" red margin from center
30
someone with recurrent strep pyogenes infections with initial myocarditis is at risk for developing what
rhemuatic valvular heart disease
31
what are signs of post streptococcal glomerulonephritis
kid with puffy face from retention of fluid by damaged kidney
dark colored urine from hematuria
hypervolemia secondary to fluid retention causing high BP
32
What is the other name for Group B beta hemolytic strep
step agalactiae
33
What does group B strep cause in neonates
meningitis, pneumonia and sepsis
34
what is the sign of meningitis in neonates
fever, vomiting, poor feeding and irritability
35
Dx of meningitis is made how
lumbar puncture
36
What are common causes of meningitis in a neonate under 3 mo age
E coli, L monocytogenes and Strep agalactiae (group b)
37
what bacteria causes meningitis later in infant's life, after 3 mo
N gonorrhea
| H influenza
38
What can group B strep cause in pregnant women
still birth, sepsis spontaneous abortion
39
What are the groups included in strep viridans
mitis, salivarius, mutans and Anginosus
40
Viridans group strep is indigenous to what area
the GI tract
41
Most of viridans strep are what category
alpha hemolytic producing greenish discoloration on blood agar
42
What are the main types of infections caused by viridans streptococci
dental infections
endocarditis
abscesses
43
What is the cause of endocarditis in viridans strep
from the dental manipulations that may enter blood and thus lead to subacture bacterial endocarditis
44
what is the clinical presentation of subacute bacterial endocarditis SBE
low fever, fatigue, anemia and heart murmurs
45
What type of endocarditis is caused by staph infections
acute infective
usually from IV drug use
shaking chills, high fevers and rapid valve destruction
46
What other bacteria can lead to subacture bacterial endocarditis
group D strep
47
What family of strep virdans causes absecesses
anginosus species that are microaerophilic
48
If the Strep intermedius bacteria from anginosus family is growing in the blood what should you order
CAT with contrast to look for abscess in hiding organ
49
What are the 2 groups of group D strep
enterococcus and non-enterococci
50
enterococci faecalis and faecium are found where
in GI, part of normal flora
| growing well in bile
51
What tpe of infections do the enterococci cause
subacute bacterial endocarditis, UTI, biliary tract infections, bacteremia
52
What type of infections do enterococci commonly cause in hospitals
prosthetic valve endocarditis sepsis after IV catheters
53
What are the enterococcie resistant to
ampicillin and vancomycin
54
infection with strep bovid (non-enterococci strep) is assoc with what
colon cancer
55
What does strep pneumococcus commonly cause in adults? children?
adults- meningitis and most common cause of pneumonia in adults
children- otitis media
56
What is the shape of strep penumococcus
diplococci, no lancefield Ag
57
what is the major virulence factor of s. pneumococcus
the capsule of polysaccharides
58
What lab tests do you order to confirm S. pneumococcus
quellung (swelling with methylene blue)
| optochin sensitivity- cannot grow on petri dish with optochin but viridans can(both alpha hemolytic)
59
what is the clinical presentation of S pneumococcal pneumonia
sudden
shaking chills
high fevers
chest pain
SOB
one or more lungs fill up with white pus and exudate seen as consolidated lobe
yellow-green sputum that has gram + lancet shaped diplococci
60
what are the 3 main bacteria that cause otitis media in children
S pneumoniae
H influenza
M catarrhalis
61
S pneumococcus is becoming resistant to what
penicillins
62
how do you differentiate enterococci and nonenterococci with the agar
enterococci grow in bile and 6.5%NaCl
| non-enterococci only grow in bile
63
What are the 3 main strains of staph
aureus, epidermidis, saprophyticus
64
How can staph aureus be differentiated from other beta hemolytic cocci
golden pigment on sheep blood agar
65
which staph is coagulase +
staph aureus only
66
What proteins does S aureus have to disable our immune system
Protein A, coagulase, hemolysins, leukocidins, penicillinase, novel penicillin binding protein
67
What protects S aureus from opsonization
Protein A
68
what prevents S aureus from phagocytosis
coagulase
69
what do the hemolysins do in S aureus
destroy RBC neutrophils, macrophages and platelets
70
What do leukocidins of S aureus do
destroy WBC
71
What produces Panton-Valentine leukocidin PVL
the CA-MRSA
72
What proteins are in S aureus that tunnel through tissue
hyaluronidase
staphylokinase
lipase
protease
73
what lyses formed fibrin clots in S aureus
the staphylokinase
74
what facilitates S aureus to colonize in sebaceous glands
lipases
75
What are the toxins that S aureus produces
exfoliatin
enterotoxins
TSST1
76
what is exfoliatin
causes skin to slough off
| scalded skin syndrome from S aureus
77
what is the role of enterotoxin from S aureus
food poisoning
78
how does TSST1 work from S aureus
binds MHC II and massive T cell activation
79
What diseases are caused by S aureus exotoxin release
Gastroenteritis
TSS
Scalded skin syndrome
80
What diseases are caused by S aureus from direct organ invasiveness
```
pneumonia
meningitis
osteomyelitis
acute bacterial endocarditis
septic arthritis
skin infections
bacteremia/sepsis
UTI
```
81
What are signs of gastroenteritis
vomiting, diarrhea, abdominal pain and occasional fever 12-24 hrs
82
where are areas that TSST1 is released
infected sutures, cutaneous and subcut infections, infections following childbirth and abortion
83
What are the signs of TSST1 caused TSS
sudden fever, nausea vomiting, and watery diarrhea
few days develop diffuse erythematous rash
palms and soles have fine peeling
blood pressure may drop and could have severe organ system dysfunction
84
What toxins cause scalded skin syndrome
exfoliative A and B toxins
85
a hospitalized patient just recovering from flu has avbrupt onset fever, chills and lobar consolidation with destructed parenchyma. what is culprit
staph caused pneumoniae
86
What are signs of meningitis, cerebritis and brain abscess from staph
high fever, neck stiffness, HA, obtundation, coma and focal neurologic signs
87
In a 10 y/o there is warm swollen tissue over bone with systemic fever and shakes. likely Dx?
staph caused osteomyelitis
88
what are signs of acute endocarditis from staph
high fever 103 and higher
| chills, myalgias
89
staph caused septic arthritis is common in what age groups
pediatrics and adults >50
90
What does impetigo look like if caused by staph
honey colored crust
| usuall around mouthy
91
what type of skin infections are caused by staph
cellulitis, impteigo, local abscesses, furuncles, carbuncles
92
What makes staph aureus R to methicillin
the penicillin binding protein 2A
93
What is most useful antibiotic agaisnt MRSA
vancomycin
94
Staphy epdermidis is found where
normal to our skin flora
| typically contaminates blood cultures from skin punture
95
how do you determine if blood contaamination of S epidermidis is from systemic infection or just that local spot
take two samples at different distances
96
S epidermidis is the most common infection where
prosthetic devices because of its production of biofilms that attach to the devices
97
What are the 2 leading causes of UTIs in young females
E coli is 1
| 2 is S saprophyticus
98
What is the main difference between Bacillus and Clostriudium even though they are both spore formers
Bacillus is aerobic
| Clostridium is anaerobic
99
When are humans usually exposed to bacillus anthracis
dealing with soil from animals or infected animal products like wool or hides
100
What are the virulent genes in B anthracis spores and what activates them
pXO1 and pXO2
| activated by inc temp to 37 degress so when introduced to host
101
what are the modes of transmission for B anthracis
germinate through skin abrasians- cutaneous
inhalation- respiratory
ingested- GI
102
what part of the body do the B anthracis invade
blood stream after macrophages
103
Describe the malignant pustule and what causes it
painless round black lesion with rim of edema caused by B anthracis that can proliferate and enter blood stream
resolve 80-90% of the time
104
What does pulmonary anthrax cause
spores are taken up mby macrophages and taken to hilar and mediastinal lymph nodes where they germinate resulting in mediastinal hemorrhage and widening(enlarged area above heart in CT)
105
What is the presentation of ingestion of B anthraces
vomiting, abdominal pain and bloody diarrhea
106
What exotoxins are encoded in pXO1- B anthracis
```
Edema factor (A subunit) increase cAMP
Protective Ag: promotes entry of EF into phagocytic cells (B subunit)
Lethal Factor: zinc metalloprotease that inactivates protein kinase and stimulates macrophage release of TNFa and IL1-beta
```
107
What does pXO2 encode for- B anthracis
genes to synthesize the poly glutamyl capsule
| D glutamic acid
108
What are the two enterotoxins released by B cereus and what do they cause?
Tx?
A heat labile toxin: nausea, abdominal pain, diarrhea 12-24 hours
A heat-stable toxin: like S aureus, short incubation period severe nausea, vomiting and limited diarrhea
Will resolve- no Antibiotics because preformed enterotoxin is the cause
109
What is the clinical presentation of botulism intoxication
b/l cranial nerve palsies, diplopia, dysphagia
general mm weakness
sudden respiratory paralysis
110
Where are infants at risk for ingestion C botulinum? symptoms? Tx?
fresh honey
constipated for 2-3 days
dysphagia and mm weakness "floppy"
give human botulism Ig IV
111
How does tetany result form tetanus toxin
taken up at NMJ and taken to CNS where it inhibits the inhibitory Ranshaw cell interneurons
stopping release of GABA and glycine
112
Clinical presentation of C tetani intoxication
severe m spasms- lockjaw
| risus sardonicus from facial mm spasms
113
What are the 3 types of patients with tetanus skin wounds
immunized more than 10 yrs prior no booster
never immunized
already having developed tetanus
114
What are the 3 infections of C perfringens
cellulitis/wound infection
Clostridial myonecrosis
Diarrheal illness
115
What does a wound infection of C. per look like
moist, spongy with crackles from gas called crepitus
116
What does Clostridial myonecrosis look like
ferment carbs producing gas
CT shows pockets of gas in muscles and sub cut
thin black fluid exudesf rom skin
117
Describe diarrhea with C per.
watery diarrhea and sometimes hemorrhagic necrosis of the jejunum
cramping, fever and severe diarrhea
pseudomembranous colitis
118
What is a precursor do C. difficile infection
braod spectrium antibiotic use
119
What is the new C difficile out there
NAP1/BI/027
15-20x more potent
new toxin- binary toxin CDT
120
What test to you order immediately if you suspect C dificile
PCR toxins A B
| sometimes EIA
121
What are the basic Tx antibiotics for C dificile
metronidazole- oral or IV
| Vancomycin- must be taken orally
122
what does diphtheria look like
gray pseudomembrane of fibrin, leukocytes, necrotic epithelial tissue in pharynx
123
What do you do immediately if you suspect diphteria in a kid
do not flake off the membrane, get a culture from swab in throat and nasopharynx
gram test
give antibiotics while doing this
124
what type of agar do you use to grow C diphtheria on and what does it look like on each
Potassium tellurite- turns black within 24 hrs
| Loefflers coagulated blood serum- add methylene blue and should see rod shaped pleomorphic bacteria
125
What do you give a patient you suspect diphtheria
Antitoxin that binds toxin only
Penicillin or erythromycin
DPT vaccine
126
How do the AB toxins of diphtheria work
B allows A to enter and inactivates elongation factor EF2 which is needed normally for translation mRNA "human antibiotic"
127
What other bacteria can lead to necrotizing pneumonia that looks like TB or nocardia? and differentiating factor?
rhodococcus equi
you will seed air fluid levels in the upper lung lobe nodules
also stains acid fast usually
128
what is a fast way to differentiate listeria from diphtheria
grow in 4-10degrees C because it likes low temp
129
What population is listeria more dangerous in
pregnant women, neonates, elderly and immunocompromised
130
When is listeria infection most common in pregnant women
3rd trimester
| avoid soft cheeses, cold cuts etc
131
when is neonatal meningitis due to listeria present
2 weeks postpartum
132
listeria is the most common cause of meningitis in what specific population
those with lymphoma or corticosteroids or receiving oral transplantation
133
describe our immune response to listeria infection
cell mediated immunity
| killing the bacteria while in our macrophages
134
what is confirmatory test for meningitis
lumbar puncture of CSF content that has nigh neutrophils and high protein
low glucose
