Exam 2 Flashcards
1
Q
Colony morphology of S. aureus on BAP, CNA, MAC, MSA
A
BAP: medium white to buttery pigment, smells like stinky socks, beta or gamma hemolysis
CNA: white colonies
MAC: NG
MSA: Mann POS @ 48 hrs
2
Q
Colony morphology of S. epidermidis on BAP, CNA, MAC, MSA
A
BAP: white dome shaped colonies, almost always gamma hemolysis
CNA: white colonies
MAC: NG
MSA: mann NEG @ 48 hours
3
Q
Colony morphology of S. saprophyticus on BAP, CNA, MAC, MSA
A
BAP: yellow or white pigment (about 50/50), almost always gamma hemolysis
CNA: white or yellow colonies
MAC: NG
MSA: mann POS or NEG; typically weaker pos rxn, may be weak pos @ 24-48 hours
4
Q
GS rxn - Staphylococcus species
A
GPC in clusters
5
Q
Purpose of catalase test
A
Differentiates staphs from streps
Determine if catalase enzyme is present
6
Q
Catalase test slide method procedure
A
- 1 drop 3-5% H2O2 on slide
- Mix 3-4 colonies into H2O2 with a loop
- Observe rxn
7
Q
Catalase test result interpretation
A
POSITIVE: RAPID PROFUSE BUBBLES (indicates catalase enzyme is present)
-Staph spp.
NEGATIVE: wimpy bubbles, no rxn
8
Q
Catalase test precautions
A
False positive results may occur:
-E. faecalis may produce wimpy rxn
-RBCs will give a false pos; do not stick look into BAP plate before picking up colonies; could pick up RBCs
from media
*must use isolated colonies
9
Q
Coagulase test purpose
A
Definitive test for Staph aureus
Determines presence of coagulase enzyme (only produced by S. aureus)
10
Q
Coagulase test rapid slide method purpose
A
Spot test that detects cell-bound coagulase
-produced by SOME strains of S. aureus
11
Q
Coagulase test reagents
A
Rabbit plasma
Fibrinogen
12
Q
Coagulase test rapid slide method procedure
A
mix rabbit plasma with 3-4 colonies on a slide
13
Q
Coagulase test rapid slide method results interpretation
A
Spot coag POS: clumps of fibrin observed; DEFINITIVE FOR S.AUREUS
Spot coag neg: must do tube method
14
Q
Coagulase test tube method purpose
A
Detects free EC coagulase
-all strains of S. aureus
15
Q
Coagulase test tube method procedure
A
0.5 mL rabbit plasma mixed with 3-4 colonies in a tube
Incubate 4 hrs to overnight @ 37C
16
Q
Rapid latex kit/Staphyloside latex kit reagents & principle
A
Latex beads coated with:
- Fibrinogen (detects cell bound coagulase)
- IgG (protein A antibodies/receptors)
principle: antiserum mixed with sample that potentially contains its target cells; if antigenic cells are present, antibodies in the antiserum will clump (agglutinate) the antigen
17
Q
Novobiocin susceptibility test interpretation
A
SUSCEPTIBLE: zone of inhibition; no growth around disk
-recorded as novo susc or novo S
RESISTANT: no zone of inhibition; growth up to disk
-recorded as novo res or novo R
18
Q
Novobiocin susceptibility test results: S. saprophyticus
A
S.saprophyticus is RESISTANT to novobiocin
19
Q
Novobiocin susceptibility test results: S. epidermidis
A
S. epidermidis is SUSCEPTIBLE to novobiocin
20
Q
List the genera and species of the FamilyMicrococcaceae (5)
A
- Staphylococcus aureus
- Staphylococcus epidermidis
- Staphylococcus saprophyticus
- Staphylococcus haemolyticus
- Micrococcus luteus
21
Q
Infections caused by S. aureus (4)
A
- Skin infections
- Wounds
- Dissemination from local infection
- Toxin mediated diseases
22
Q
Infections caused by S. aureus:
Boils
A
AKA furuncles
Begins as folliculitis
23
Q
Infections caused by S. aureus:
Carbuncles
A
Infection from boil spreads to surrounding/deeper tissue
happens when several furuncles coalesce
24
Q
Infections caused by S. aureus:
Impetigo
A
primarily infection of children
-common source is nose; runny nose kid
2 kinds: bolus impetigo and pustule impetigo
25
Infections caused by S. aureus:
bolus impetigo vs pustule impetigo
Bolus impetigo:
- blister-like
- 80% S. aureus, 20% S. pyogenes
Pustule impetigo:
- more zit-like
- usually S. pyogenes
26
Infections caused by S. aureus:
Dissemination from local infection - 6 conditions
1. Septicemia
2. Bacteremia
3. Osteomyelitis
4. Pneumonia
5. Endocarditis
6. Meningitis
27
Septicemia
Bacteria in blood multiplying & causing symptoms
28
Bacteremia
Bacteria in blood but no symptoms
bacteria enter bloodstream through site of infection
29
Osteomyelitis
Inflammation of the bone marrow and surrounding bone
Can sit in bone marrow dormant and flare back up when disturbed, usually by trauma
30
Pneumonia
Infection of lungs; alveoli and bronchioles become filled with fluid
31
Endocarditis
Infection of the inner lining of heart and potentially valves
nonspecific flu-like symptoms
Drug users
32
Meningitis
Inflammation of the meninges
33
Infections caused by S. aureus:
Toxin mediated diseases (3)
1. Toxic shock syndrome
2. Food poisoning
3. Staphylococcal scalded skin syndrome
34
Infections caused by S. aureus:
Toxic shock syndrome
Toxin: TSST-1
- absorbed into blood stream
- causes fever, hypotension, shock, death in some cases
35
Infections caused by S. aureus:
Food poisoning
Food left out at room temp 2+ hours (mayo based foods)
Enterotoxins A & D
- preformed toxins secreted by bacteria
- symptoms start in 2-8 hours
Source = carriers
food poisoning caused by enterotoxin left in food from growth of bacteria rather than by a bacterial infection
36
Infections caused by S. aureus:
Staphylococcal scalded skin syndrome
AKA Ritter’s disease
caused by exfoliative toxin
-causes epidermis to separate from cutaneous layer
More common in kids
37
Pathogenic mechanisms of S. aureus: (3 categories)
1. Invasive mechanisms
2. Toxin production
3. Cytolytic toxins
38
Pathogenic mechanisms of S. aureus: Invasive mechanisms (6)
1. coagulase
2. hyaluronidase
3. protein a
4. lipase
5. staphylokinase
6. beta lactamase
39
Pathogenic mechanisms of S. aureus: Invasive mechanisms
coagulase
AKA clumping factor
enzyme that forms fibrin (clot) from fibrinogen
allows org to form clot around itself to protect from body defenses
***ONLY S. AUREUS SYNTHESIZES COAGULASE
40
Pathogenic mechanisms of S. aureus: Invasive mechanisms
hyaluronidase
AKA spreading factor
enzyme that breaks down hyaluronic acid in connective tissues and allows org to spread and break up cells
41
Pathogenic mechanisms of S. aureus: Invasive mechanisms
protein a
cell wall protein unique to S. aureus
prevents antibody mediated phagocytosis
can bind to FAB and Fc portion of IgG
covers Fc portion; without Fc exposed, phagocyte receptor can't attach and phagocytosis can't occur
42
Pathogenic mechanisms of S. aureus: Invasive mechanisms
lipase
breaks down oils (lipids) produced by sebaceous glands
allows staph to grow on surface of skin and in cutaneous oil glands
all staph spp. produce this
43
Pathogenic mechanisms of S. aureus: Invasive mechanisms
staphylokinase
acts as antagonist to coagulase
dissolves fibrin strands
allows org cells to leave clot when space and nutrients become limited
44
Pathogenic mechanisms of S. aureus: Invasive mechanisms
beta lactamase
AKA penicillinase
breaks down penicillin; breaks bond in lactam ring, rendering it inactive
now present in 90% of S. aureus strains
45
Pathogenic mechanisms of S. aureus: toxin production (3)
1. Enterotoxin A-E
2. Exfoliative toxin
3. Toxin 1
46
Pathogenic mechanisms of S. aureus: toxin production
Enterotoxin A-E
affects lining of GI tract
stimulates intestinal muscle contractions, nausea, and intense vomiting
47
Pathogenic mechanisms of S. aureus: toxin production
Exfoliative toxin
AKA epidermolytic toxin
causes patients skin cells to separate from each other and slough off body
48
Pathogenic mechanisms of S. aureus: toxin production
Toxin 1
TSST-1
causes toxic shock syndrome
49
Pathogenic mechanisms of S. aureus: cytolytic toxins
alpha, beta, delta, gamma
toxic for many cells including:
- leukocytes
- erythrocytes
- platelets
- macrophages
50
CoNS (4)
S. epidermidis
S. saprophyticus
S. haemolyticus
S. lugdunensis
51
CoNS: S. epidermidis
most common aerobic bacteria on skin
cause of 70-80% of CoNS infections
Low virulence - opportunistic
Causes nosocomial infections
Slime layer is an important virulence factor for S. epi
52
CoNS: S. saprophyticus
UTIs in sexually active women and older males
adhere to epithelial cells lining urogenital tract
-causes cystitis
53
CoNS: S. haemolyticus
NF usually seen in clinical samples
54
CoNS: S. lugdunensis
NF on skin
can cause osteomyelitis and septicemia
most known for causing aggressive endocarditis
55
Nosocomial infection
hospital acquired infection (HAI)
plastic prosthetic devices, catheters, IVs
-slime layer; adherence factor
56
can report out as CoNS unless:
Urine or sterile sites, esp prosthetic devices
would want to work up further in these cases
57
Genera that are considered pathogenic cocci
```
Staphylococcus
Micrococcus
Streptococcus
Enterococcus
Neisseria
Moraxella
```
58
Lancefield classification scheme
based on components found in cell wall
causes different serological rxns
divides streps into three categories
59
3 categories of strep based on lancefield classification
1. C carbohydrates
2. Lipoteichoic acid
3. Non-lancefield
60
Streptococcus species (7 groups)
```
S. pyogenes
S. agalactiae
S. pneumoniae
Viridans group (S. mutans, S. sanguis, S. salivarius, S. mitis, S. milleri)
E. faecalis
E. faecium
Group D streps
```
61
Characteristics of Streptococcus: GS rxn
GPC
62
Characteristics of Streptococcus: cellular morphology
usually in chains
S. pneumo is diplococci
63
Characteristics of Streptococcus: Serologic groupings
lancefield groups
64
Characteristics of Streptococcus: colony morphology
non-pigmented, small colonies
ground glass
translucent
65
Characteristics of Streptococcus: hemolysis
alpha, beta, gamma
CAN be used for ID
66
Lancefield classifications: C carbohydrates
5 groups: A, B, C, F, G
| -each cause different serological rxns
67
Lancefield classifications: lipoteichoic acid
no C carbohydrate
serological rxn caused by lipoteichoic acid
group D streps: S. bovis, S. equinus, E. faecalis, E. faecium
68
Lancefield classifications: non-lancefield
neither C carbs nor lipoteichoic acid serotypes
S. pneumo, viridans streps
69
Lab ID of GAS: hemolysis
BETA - complete lysis around individual colonies
due to streptolysin S & O
70
Lab ID of GAS: antimicrobial
Bacitracin susceptible (99%)
71
Streptolysin S
O2 stable
| OK in presence of O2
72
Streptolysin O
O2 labile
| NOT O2 tolerant
73
Criteria needed to report throat culture GAS positive (3)
1) strong beta hemolysis
2) streptolysin O positive
3) bacitracin susceptible
reported as: S. pyogenes or GAS
74
SXT plate
GAS isolation media
BAP + sulfamethoxazole + trimethroprim
75
PYR test
spot test - PYR enzyme
positive = RED disk after adding cinnamaldehyde reagent (2-5 min)
100% definitive for GAS
76
PYR test precautions
not enough organism can result in false negative
77
GAS rapid test
extracts C carb from swab using reagent
*IF NEGATIVE - must do culture; bacitracin + stab o
78
latex agglutination kits procedure (and what groups?)
for groups A-D, F, G
1. rapid extraction of C carb and liptoteichoic acid
2. drop each set of latex beads (A,B,C,D,F,G) on card (antibodies for each C carb and lipoteichoic acid)
3. one drop of extracted organism
4. tilt card for 2-3 minutes
79
Pathogenicity of GAS (6)
M protein
DNase
Hyaluronidase
Streptokinase
Streptolysin O and S
Pyrogenic exotoxins
80
Pathogenicity of GAS (6)
M protein
DNase
Hyaluronidase
Streptokinase
Streptolysin O and S
Pyrogenic exotoxins
81
Pathogenicity of GAS: m protein
unique to S. pyogenes
membrane protein attached to peptidoglycan
80 different serological groups
-this is why you can get it a bunch of times
82
Pathogenicity of GAS: m protein fxns
resists phagocytosis
adherence to mucosal cells
destabilizes complement and interferes with opsonization and lysis
*similar to S. aureus mechanisms
83
Pathogenicity of GAS: DNase
enzyme that breaks down DNA
gives org more room to move (pus is very viscous; makes it hard to move around/spread)
84
Pathogenicity of GAS: hyaluronidase
"spreading factor"
breaks down connective tissue/hyaluronic acid in connective tissue
85
Pathogenicity of GAS: streptokinase
breaks up fibrin clots
helps w/ spread of org
86
Pathogenicity of GAS: streptolysin O & S
membrane bound proteins
breaks down/lyse RBCs, WBCs, and platelets
interfere with the O2 carrying capacity of blood, immunity, and blood clotting
after GAS has been phagocytized, releases streptolysins into the cytoplasm of the phagocyte; causes lysosomes to release their contents; which lyses the phagocyte and releases the bacteria
87
Pathogenicity of GAS: pyrogenic exotoxins
3 toxins that cause macrophages to release cytokines
causes fever, rash, shock
88
Diseases of GAS (2 groups)
1. localized infections
| 2. sequelae diseases
89
Diseases of GAS (2 groups)
1. localized infections
| 2. sequelae diseases
90
Diseases of GAS: localized infections definition and examples
rapid onset
purulent, pus, build up of fluid
includes: pharyngitis, impetigo, erysipelas, cellulitis
91
Diseases of GAS: localized infections definition and examples
rapid onset
purulent, pus, build up of fluid
includes: pharyngitis, impetigo, erysipelas, cellulitis
92
Diseases of GAS: pharyngitis
AKA strep throat; inflammation of pharynx
abrupt sore throat
malaise, fever, headache
most prevalent ages 5-15: 90% bacterial (90% GAS), 10% viral
for adults: 10% bacterial, 90% viral
*M protein antibodies
93
Diseases of GAS: impetigo
usually caused by GAS
GAS can also cause bolus impetigo
94
Pyoderma
confined, pus-producing lesion
95
Diseases of GAS: Erysipelas
clear demarcations (edges of the infection well defined)
when a strep infection also involves the surrounding lymph nodes and triggers pain and inflammation
most common on faces of kids
96
Diseases of GAS: Cellulitis
may develop following deeper invasion of GAS following erysipelas
may be serious, even life threatening esp in cases where bacteria become septicemic
97
Diseases of GAS: sequelae diseases definition
post-streptococcal diseases
98
Diseases of GAS: scarlet fever
AKA scarletina
appears 1-2 days after pharyngitis:
- S. pyogenes releases pyogenic exotoxins
- produces rash that usually begins on chest (goes away about a week later)
- strawberry red tongue
- sloughing off of skin
99
Diseases of GAS: rheumatic fever cause and consequences
complication of untreated S. pyogenes pharyngitis
inflammation leads to damage of heart valves and muscle
thought to be caused by immune response to GAS:
- antibodies targeting the bacteria cross react w/ heart antigens
- bodies immune response gets confused
100
Diseases of GAS: acute glomerulonephritis
antibody and antigen compounds not removed from blood
- get stuck/accumulate in glomeruli of nephrons
- causes inflammation of nephrons and reduced blood flow (results: hypertension, low urine output)
- can lead to destruction of kidneys
101
Diseases of GAS: invasive GAS disease
GAS secretes enzymes & toxins that destroy fascia connective tissue around muscle
*org can move ~1 inch per hour! very fast!
amputation sometimes only way to stop it; 50% of patients die
102
Factors that lead to fast spread of GAS
DNase
hyaluronidase
exotoxins
streptokinase
(basically all virulence factors in combination)
103
Diseases of GAS: streptococcal toxic shock syndrome
can spread from original site of infection and cause septicemia
*mostly seen in immunocompromised individuals
symptoms include: inflammation, pain, fever, chills, nausea, vomiting; can lead to shock, organ failure, death (over 40% patients die)
104
Importance of diagnosing pharyngitis caused by GAS
consequences of GAS very serious very dangerous and can spread very rapidly without intervention
105
Treatment of GAS
penicillin
for penicillin sensitive patients: erythromycin, cephalosporin
bacitracin (topical)
106
Rapid strep ELISA steps/explanation
1) extraction of GAS C carb from swab
107
Methicillin
semi-synthetic form of penicillin
not inactivated by beta lactamase
108
MRSA
methicillin-resistant Staphylococcus aureus
109
protein adhesin
secreted by pathogenic pneumococci
protein that mediates binding of cells to epithelial cells of the pharynx
110
Sty definition
folliculitis that occurs at base of eyelid
111
empyema definition
when infection from pneumonia spreads to space between lung and chest wall; pus builds up
112
empyema definition
when infection from pneumonia spreads to space between lung and chest wall; pus builds up
113
Problems associated with Vancomycin (2)
1. has some serious side effects
| 2. takes much longer to kill the bacteria than oxacillin
114
GBS
S. agalactiae
115
GBS lab identification: GS
no specific pattern, pairs kinda, clusters kinda
GPC
116
GBS lab identification: hemolysis
smoky beta hemolysis
translucent colonies
GBS does NOT have streptolysin O
117
GBS lab identification: PYR
negative
118
GBS lab identification: antimicrobials
bacitracin resistant
119
GBS lab identification: CAMP test
positive (arrowhead)
120
CAMP test method/reasoning
action of 2 enzymes:
1. beta hemolysin of S. aureus
PLUS
2. Beta hemolysin of S. agalactiae
creates an enhanced zone of hemolysis (arrowhead) after overnight incubation
121
GBS lab identification: hippurate hydrolysis
positive (purple)
122
Hippurate hydrolysis method/reasoning
Sodium hippurate + colonies of organism are incubated overnight @ 37C
123
GBS screen reason
to protect pregnant mothers and newborns
124
GBS method/procedure
done around 35-37 weeks of pregnancy
vaginal/rectal swab put into LIMs broth and incubated overnight; then plated on BAP for ID
OR
Strep B carrot broth - takes about 6 hrs
125
LIMs broth ingredients
todd hewitt broth + colisitin + nalidixic acid
THB = enriched media for GBS
Colistin + nalidixic acid = knocks out normal flora
126
Strep B carrot broth
chromogenic pigments for ID of GBS (pos = orange)
dont have to plate after
127
Diseases of GBS/S. agalactiae (3)
1. maternal septicemia
2. neonatal infections
3. infections of female GU tract
*part of NF in vagina for 10-30% of females
128
Diseases of GBS/S. agalactiae: maternal septicemia
post partum infections
puerperal fever
129
Diseases of GBS/S. agalactiae: neonatal infections
GBS responsible for ~1/3 of neonatal infections
early onset:
- pneumonia
- meningitis (70% of cases of meningitis in newborns is GBS)
late onset: around 3 months after birth
- not as severe usually
- usually acquired from environment rather than mom
130
Diseases of GBS/S. agalactiae: infections of female GU tract
UTI
131
GBS antimicrobial therapy
penicillin
prophylactically administered to newborns whose mothers are colonized with GBS
132
S. pneumoniae lab identification: GS
GP diplococci
lancet shape
capsule can be seen sometimes
133
S. pneumoniae lab identification: hemolysis
alpha hemolysis *met hemoglobin!*
can be used to ID S. pneumo
always recorded from BAP and CNA (never CHOC obviously)
134
S. pneumoniae lab identification: colony morphology
pinpoint alpha on BAP, small pinpoint on CNA
"penny edge"
-autolytic enzymes dissolve and collapse center of colony
135
S. pneumoniae lab identification: antimicrobials
optochin (p disk) susceptible
disk: ethylhydrocupreine hydrochloride
136
S. pneumoniae lab identification: bile solubility test
positive
137
bile solubility test method/purpose
triggers autolytic enzymes
tube method
plate method
138
quelling rxn
rarely used today
ID S. pneumo
a type of specific capsular antigen added to the org cells which causes the cell capsule to swell; antibodies bind to the bacterial capsule
visualized microscopically
quellung = german word for swelling
139
Sputum sample notes:
S. pneumo considered NF in URT (esophagus, larynx, and above)
LRT considered sterile
sputum collection = deep lung aspirate
-high # epis, probably just spit not sputum
140
Diseases of S. pneumo (3)
1. pneumonia
2. ear and eye infections
3. meningitis and septicemia
*S. pneumo is an opportunistic pathogen
141
Diseases of S. pneumo: pneumonia
aka pneumococcal pneumonia
symptoms: high fever, sharp chest pains, difficulty breathing, lung congestion, rust colored sputum
142
Diseases of S. pneumo: ear and eye infections
ear infections aka otitis media
50% of all cases due to H. flu and S. pneumo
143
Diseases of S. pneumo: meningitis and septicemia (most common causative agents)
```
#1 N. meningitidis
#2 S. pneumo
```
144
S. pneumo virulence factors: (4)
1. capsule
2. pneumolysin enzyme
3. secretory IgA protease
4. Phosphorylcholine
145
S. pneumo virulence factors: capsule
produces polysaccharide capsule
80 different capsular antigens
colonies from virulent strains mucoid on BAP
*avirulent strains produce no capsule
146
S. pneumo virulence factors: pneumolysin enzyme
binds to cholesterol in membranes of epithelial cells
produces transmembrane pores that result in lysis of the cell
suppresses digestion of engulfed bacteria which interferes w/ action of lysosomes
147
S. pneumo virulence factors: phosphoryl choline
in S. pneumo cell wall
binds to receptors in lungs, meninges, & blood vessel walls; can pass across these cells and into blood
stimulates cells to engulf bacteria
148
S. pneumo virulence factors: secretory IgA protease
body limits movement to lungs by binding active sites of secretory IgA; this then gets trapped in the mucous
protease DESTROYS IgA
149
S. pneumo antimicrobial treatment
penicillin
erythromycin, others
150
Pneumococcal vaccine
available for the most common serotypes of S. pneumo
consists of purified capsular material from 23 different strains (which covers about 94% of clinical isolates)
recommended for over age 65
151
Enterococcus spp. and GDS lab identification: GS
GPC
152
Enterococcus spp. and GDS lab identification: cell morphology
no particular morphology
can be kind of oval in shape, elongated
153
Enterococcus spp. and GDS lab identification: colony morphology
translucent to light gray colonies
154
Enterococcus spp. and GDS lab identification: hemolysis
beta, alpha, gamma
BUT generally gamma
155
Enterococcus spp. and GDS lab identification: bile esculin hydrolysis
BOTH spp. positive - black color change
156
bile esculin hydrolysis
bile - Enterococcus and GDS grow in present of bile but other orgs are inhibited by it, especially GPC
esculin - Enterococcus and GDS hydrolyze esculin
esculin --> esculetin + glucose --> reacts w/ ferric citrate in media --> BLACK color
157
Enterococcus spp. and GDS lab identification: NaCl broth
Enterococcus POS, GDS NEG
| yellow color change
158
NaCl broth
nutrient broth + 6.5% NaCl
*set up 6.5% NaCl broth and Bile esculin broth at the same time
159
Enterococcus spp. and GDS lab identification: PYR
enterococcus positive
| GDS negative
160
Enterococcus catalase rxn
WEAK CATALASE POSITIVE NOT TRUE POSITIVE
161
important Enterococcus spp.
E. faecalis
E. faecium
* N.F. in intestinal tract (entero=intestinal) and URT (upper respiratory tract)
* common cause of nosocomial infections and UTIs
162
non-enterococcus/GDS spp.
Streptococcus bovis
Streptococcus equinis
*zoonotic diseases
163
Nosocomial infection definition
opportunistic org that infects an individual after 3 days of being in the hospital
164
GDS antimicrobials
GDS susceptible to penicillin
165
Enterococcus antimicrobials
Enterococcus resistant to penicillin
Vancomycin currently drug of choice
166
VRE
vancomycin resistant enterococcus
167
enterococcosel plate with vancomycin
selective and differential plating media
growth on plate would indicate RESISTANT strains of enterococcus
sometimes used with urine cultures as primary plating media
168
Strep viridans spp.
```
S. mutans
S. sanguis
S. salivarius
S. mitis
S. milleri
```
major components of URT NF
not primary pathogens (low virulence) but may become opportunistic
169
Viridans meaning
means "greening"
170
Strep viridans hemolysis
alpha on BAP
171
causative agent of tooth decay
S. mutans
172
major disease of Strep viridans
bacterial endocarditis
commonly preceded by dental extraction, oral surgery, and occasionally after routine teeth cleaning
can lead to heart failure
173
major disease of Strep viridans
bacterial endocarditis
commonly preceded by dental extraction, oral surgery, and occasionally after routine teeth cleaning
can lead to heart failure
174
Group C Streps
frequently causes infection in many animal species but are rare causes of disease in humans
175
how to determine colony forming units per mL
colonies x dilution factor = CFU/mL
176
dilution factor for 1 microliter loop (.001 mL)
1000
177
dilution factor for 10 microliter loop (.01 mL)
100
178
clean catch definition
midstream catch
179
Urine cultures interpretive and reporting guidelines: when the colony count on a plate exceeds 100 colonies, report out as ______
a MAXIMUM of "> 100,000 CFU/mL"
180
Urine cultures interpretive and reporting guidelines: when there is a single pathogen or two potential pathogens > 20,000 CFU/mL what should you ID?
ID to genus and species
181
Urine cultures interpretive and reporting guidelines: predominant growth of one org with 2 or 3 additional orgs, what should you ID?
ID predominate org and describe the others
182
Urine cultures interpretive and reporting guidelines: no predominate org with 3+ org types, what should you ID?
probably non-clean catch sample
include:
1) CFU/mL
2) description of the colonies with GS rxn
3) # of colony types present
183
Urine cultures interpretive and reporting guidelines: < 10,000 CFU/mL with 1, 2, 3, or more colony types, what should you ID?
probably non-clean catch sample
include:
1) CFU/mL
2) description of the colonies with GS rxn
3) # of colony types present
184
Urine cultures interpretive and reporting guidelines: do not use _____ when reporting urine cultures
the term normal flora
185
urine cultures commonly contaminated with ___?
urethral normal flora
CoNS, Streps, Lactobacillus, diptheroids (GPRs)
186
Urine sample types: clean catch
pt instructed to clean genital area thoroughly before collection to reduce contamination with NF
187
Urine sample types: midstream
pt usually instructed to begin voiding and then collect urine
helps flush out small amounts of bacteria that may be present in urethra which are not causing infection
188
Urine sample types: catheterized
urine collected by passing a catheter through urethra into the bladder
meant to decrease contamination with urethral flora or in patients who may be unable to urinate
189
Urine sample types: suprapubic aspiration
urine collected by passing a needle into bladder
used sometimes on infants and in other difficult cases
190
Urine specimen requirements
urine culture should be set up within 1 hour of receipt or refrigerated
otherwise bacteria (including NF, contaminants) will quickly multiply which makes interpretation of culture difficult
191
patient factors to consider when interpreting urine cultures
age
history
192
true infections will often yield ______
50,000 CFU/mL or more
193
you might see small numbers of orgs in _____
kidney infections
infant infections
UTIs in pregnant women
*should still be considered significant
194
orgs to look for in urine cultures
CoNS (esp in young women and hospitalized patients)
Coliforms (esp E. coli) (common in all ages and hospitalized patients)
Enterococcus spp.
GBS and other types of Strep
Pseudomonas spp. and other GNBs
Yeasts such as Candida spp.
195
Genus' in the family Neisseriaceae
Neisseria
Moraxella
GNDC with flattened adjacent sides
196
Species in the family Neisseriaceae
N. gonorrhoeae (very common, a leading STD)
N. meningitidis (a leading cause of meningitis, can be NF)
N. sicca, N. subflava, N. flavescens, N. mucosa, N. cinerea (typically non pathogenic)
Moraxella catarrhalis (opportunistic pathogen)
197
Special requirements for Neisseria gonorrhoeae specimens: Specimen collection and transport
1) cannot use calcium alginate or cotton swabs (dacron or rayon swabs instead)
2) sensitive to drying during transport to lab (must be plated w/i 6 hrs; gonococcal (GC) transport media)
198
Special requirements for Neisseria gonorrhoeae specimens: temp requirements
specimen must be kept at room temp or above
199
Special requirements for Neisseria gonorrhoeae specimens: nutrient requirements
requires hemin (bc fastidious)
NG on BAP
WILL grow on CHOC
200
Special requirements for Neisseria gonorrhoeae specimens: air requirements
prefers 3-5% CO2
CAPNOPHILE
201
JEMBEC plate
sodium bicarbonate + sodium citrate disk (helps with CO2 levels)
202
Specimen sources for Neisseria gonorrhoeae (4)
Urethra (urethral discharge), vaginal, cervical, and anal swabs
Surgical tissues from PID patients (pelvic inflammatory disease)
Throat swabs
Joint fluids
203
Specimen sources for Neisseria meningitidis (2)
CSF (if > 1 mL, centrifuge 1500 x g for 15 min)
- direct GS
- plated onto CHOC
Blood
204
Primary plating media for Neisseria gonorrhoeae (4)
Thayer Martin (TM)
Modified Thayer Martin (MTM)
New York City (NYC)
CHOC
205
Precautions for plating Neisseria specimens
CHOC plate should always be included because 5% of N. gonorrhoeae strains are susceptible to vancomycin
Species related to Neisseria can also grow on the Neisseria plating media, specifically Kingella and Acinetobacter spp. (GNRs)
206
Modified Thayer Martin composition
CHOC + 4 antibiotics
1. vancomycin - inhibits GPC
2. colistin - inhibits GNRs
3. nystatin - inhibits yeast
4. Trimethoprim lactate - inhibits Proteus spp.
(same as TM + one antibiotic)
207
Modified Thayer Martin composition
CHOC + 4 antibiotics
1. vancomycin - inhibits GPC
2. colistin - inhibits GNRs
3. nystatin - inhibits yeast
4. Trimethoprim lactate - inhibits Proteus spp.
(same as TM + one antibiotic)
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New York City plate
transparent media w/ hemin added
4 antibiotics:
1. vancomycin - inhibits GPCs
2. colisitin - inhibits GNRs
3. amphotericin B - inhibits yeast
4. trimethoprim lactate - inhibits Proteus spp.
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Neisseria lab ID: GS rxn
GNDC
210
Neisseria lab ID: colony morphology
tiny, gray, translucent @ 24 hours
N. gonorrhoeae will NOT grow on BAP
N. meningitidis WILL grow on BAP and CHOC
211
Neisseria lab ID: air requirements
capnophile (prefers higher CO2)
212
Neisseria lab ID: catalase
POSITIVE
213
Neisseria lab ID: oxidase
POSITIVE
214
Oxidase test reagent and methods (2)
reagent: N,N-dimethly-p-phenylene-diamine HCL
methods:
1. glass slide: transfer colonies using wooden stick, add one drop of reagent onto filter paper
2. plate method: on a 24 hr plate, actively growing culture drop reagent straight onto plate
215
Oxidase test precautions (3)
1. use a wooden stick to transfer colonies NOT a steel loop
2. do NOT use MAC plate to test for oxidase, will give false negative
3. if E. coli is used as negative control directly from fridge (cold), it will give a weak oxidase rxn
216
Virulence factors of pathogenic Neisseria gonorrhoeae (5)
1. Capsule
2. Pili (fimbriae)
3. Cell wall proteins
4. Endotoxin
5. IgA protease
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Virulence factors of pathogenic Neisseria gonorrhoeae: capsule
Functions:
1. keep from drying out
2. inhibit phagocytosis
3. adherence to tissues
**N. meningitidis - 5 strains encapsulated (a, b, c, y, w135)
218
Virulence factors of pathogenic Neisseria gonorrhoeae: pili (fimbriae)
both strains! but esp N. gonorrhoeae
Functions:
1. inhibit phagocytosis
2. adherence to host tissue
3. pass genetic info from strain to strain
* *N. gonorrhoeae have 5 strains:
- T1 & T2 have pili - VIRULENT
- T3, T4, T5 no pili - avirulent
219
Virulence factors of pathogenic Neisseria gonorrhoeae: cell wall proteins
aka outer membrane proteins
basis of ELISA tests
- Protein I
- Protein II
- Protein III
also inhibit phagocytosis
220
Virulence factors of pathogenic Neisseria gonorrhoeae: endotoxin
outer portion of cell; lipoligosaccharide instead of LPS; lacks O antigen
functions:
1. inhibits phagocytosis
2. cause damage to host cell tissues
221
Virulence factors of pathogenic Neisseria gonorrhoeae: IgA protease
breaks down IgA
mucosal cells with secretory IgA: URT, GI, urogenital, saliva, tears, breast milk
222
diseases of Neisseria gonorrhoeae (3)
1. gonorrhoeae
2. PID
3. gonococcal opthalmia
223
diseases of Neisseria gonorrhoeae (3)
1. gonorrhoeae
2. PID
3. gonococcal opthalmia (opthalmia neonatorum)
224
diseases of Neisseria gonorrhoeae: gonorrhea
Males: acute urethritis, purulent discharge, dysuria
Females: dysuria, lower abdominal pain, vaginal bleeding
225
diseases of Neisseria gonorrhoeae: PID
pelvic inflammatory disease
infection of uterus, fallopian tubes, and adjacent pelvic structures
caused by two types of STDs
25% of women with gonorrhea contract PID
can led to infertility or ectopic pregnancy
226
diseases of N. meningitidis (2)
1. meningitis
| 2. meningococcemia
227
diseases of N. meningitidis (2)
1. meningitis
| 2. meningococcemia
228
Non pathogenic Neisseria (5)
1. N. sicca
2. N. subflava
3. N. flavescens
4. N. mucosa
5. N. cinerea
229
penicillin mechanism of action
generally effective against gram positive cell walls
interferes with synthesis of peptidoglycan
230
Penicillin binding proteins (PBPs)
bind to the transpeptidases
231
MRSE
methicillin resistant S. epidermidis
232
VRSE
vancomycin resistant S. epidermidis
233
Penicillin binding proteins (PBPs)
bind to the transpeptidases (enzymes) that bind the tetrapeptide crossbridge to the NAM molecules in GPOs during synthesis of peptidoglycan
penicillin binds directly to these PBPs and prevents the crossbridges from binding to the NAM
234
beta lactamase
enzyme that is able to inactive penicillin
breaks apart the beta lactam ring of penicillin which produces an inactive form of the drug called penicilloic acid
~95% of S. aureus strains produce beta lactamase
235
methicillin mechanism of action
same as penicillin; binds to transpeptidases (PBPs)
236
mechanism of MRSA resistance to methicillin
MRSA strains have modified transpeptidases so that the drug cannot recognize the enzyme
237
MRSA drug of choice
vancomycin
238
vancomycin drawbacks (2)
1. has some serious side effects
| 2. takes much longer to kill the bacteria than oxacillin
239
VRSE
vancomycin resistant S. epidermidis
240
benefits of oxacillin (2)
1. more stable than methicillin
| 2. longer shelf life
241
VRSA
vancomycin resistant S. aureus
