Microbiology

Front 1

When classifying organisms, the genotypic class is based on genetic relatedness and is related to...

And the phenotypic class is based on....

Back 1

Genotypic: based on nucleic acid base composition and ratio

Phenotypic: traditional microbiology, morphology, biochemical characteristics , antigenic relationships (observable)

Front 2

The biological classification of organisms uses specific nomenclature, what is this pyramid of terms?

Back 2

Kingdom

Phylum

Class

Order

Family

Genus

Species

Front 3

If a host is infected by a micro-organism, but not harmed it is called...

If the host IS harmed it is referred to as...

Back 3

Not harmed: Colonization

Harmed: Infectious disease

Front 4

What is the word that describes a microorgnaism that is CAPABLE of causing an infectious disease?

Back 4

Pathogen

Front 5

DEFINE:

1. True Pathogen

2. Opportunist Pathogen

3. Nosocomial infection

Back 5

1. True pathogenMicroorganism that causes disease in healthyimmunocompetent host

2. Opportunist pathogenNormally nonpathogenic microorganisms that are capable ofcausing infection in an immunocompromised host

3. Nosocomial infectionInfection acquired in the hospital or other health caresetting

Front 6

The virulence of an organism is the relative ability of a microorganism to cause disease, or the degree of pathogenicity.

It is based upon:

Back 6

Virulence is based on:

1. the number of organisms

2. virulence factors (organism characteristics (tools) thatprotect organism against host attack or mediate damagingeffects on host cells)

Front 7

The most common way that microorganisms resists phagocytosis in the host is through this characteristic...

Back 7

Having a polysaccharide capsule enables microorganisms to resist phagocytosis because it masks the surface receptors. Organisms with capsules tend to be more virulent.

Front 8

What are three ways that microorganisms can resist phagocytosis (other than having a polysaccharide capsule):

Back 8

1. release of potent materials such as hemolysin and leukocidin (toxic to WBC)

2. Inhibit WBC chemotaxis

3. Protein A (interferes with binding of host's antibodies)

Front 9

What bacterial structures promote adhesion in the host?

Back 9

1. Adhesin - cell surface structure that mediates attachement

2. Pili - in gram negative

3. Fimbriae in both gram negative and gram postive

Front 10

After attachment to the host cell, a microorganism must proliferate. This proliferation is done through two key tactics:

Back 10

1. IgA protease development (bacterial enzyme that degrades IgA found atmucosalsurfaces)

2. Shifting key cell surface antigens so cannot be recognized byhost’s immunoglobulins

Front 11

Define:

1. Toxin:

2. Exotoxin

3. Endotoxin

Back 11

1. Toxin: Protein substance produced by some pathogenic bacteriathat is highly toxic for other living organisms (a poison)

2. Exotoxin: Gram-pos bacteria (some gram-neg), toxin that targets specific host cells, released by bacteria, heat labile (except Staph enterotoxin)

2. Endotoxin: part of the bacterial membrane

Front 12

What is an example of an endotoxin of gram-negative bacteria?

Back 12

Lipid A portion of LPS (which is a portion of the outer membrane of the cell wall)

Heat stable.

Ex. Gram-neg septicemia

Front 13

What is: A toxin produced by a microorganism that is specific for the intestinal mucosa? Can be either an endotoxin or an exotoxin. Example: Staphfood poisoning

Back 13

ENTEROTOXIN

Front 14

What is: A toxin produced by a microorganism that is destructive tonerve tissue? Example: tetanus toxin.

Back 14

NEUROTOXIN

Front 15

Which two extracellular enzymes are used by microorganisms to help them persist in the host and cause disease?

Back 15

Proteases

Hyaluronidases

These liquefy hyaluronic acid ofconnective tissue matrix and aid in spreading bacteria into tissues

Front 16

ANTIMICROBIAL SUBSTANCES: How do hosts protect themselves against pathogens?

Back 16

Lysozymes-hydrolyzes peptidoglycan

Antibodies-secretory IgA

β-lysins-released from platelets, kill gram positivebacteria

Interferons-bind to nonviral infected cells-inhibitviral replication

Front 17

Normally Sterile Body SitesColonization of one of these sites generallyinvolves a defect or breach in the naturaldefenses that creates a portal of entry:

Back 17

Brain: Central Nervous System

Blood: Tissues; Organ systems

Sinuses: Inner and Middle Ear

Lower Respiratory Tract: Larynx; Trachea;Bronchioles(bronchi); Lungs; Alveoli

Kidneys: Ureters; Urinary Bladder

Uterus: Endometrium (Inner mucous membrane ofuterus ); Fallopian Tubes

Front 18

Phagocytosis (non-specific response) involves:

Back 18

Chemotaxis - movement of phagocytic cells (PMNs andmono/macros)into tissues

Attachment – opsonization enhances PMN attaching tomicroorganism

Ingestion – degranulation (lysosomes release contents)

Killing

Front 19

_______ is a mixture of active or inactive neutrophils, otherinflammatory cells, bacterial cells, and extravascular fluid

Back 19

PUS

Front 20

_________________/____________/__________________ reaction: inflammatory response toinfections resulting in theaccumulation of pus

Back 20

Suppurative/Pyogenic/Purulent reaction– inflammatory response toinfections resulting in theaccumulation of pus

Front 21

The two specific immune system responses of the host include:

Back 21

Humoral immunity – antibody-mediated immunity

Cellular immunity – cell-mediated immunity

Front 22

What are the three clinically significant genera of all the GPC?

Back 22

Staphylococcus, Streptococcusand Enterococcus

Front 23

Staphylococcus

Coagulasepositive (CPS): ________

Coagulase negative (CNS): _________, ___________, ____________

Back 23

Coagulase positive (CPS): S. aureus

Coagulase negative (CNS): S. epidermidis •S. saprophyticus •S. lugdenensis •Other CNS

Front 24

Most staph are facultative anaerobes

Back 24

can use either aerobic respiration and/orfermentationdependingon the availabilityof oxygen,doesnot solely depend on aerobic respirationfor growth

Front 25

Staph:

Grow on any nutrientmedia that contains _______ •Inhibitedby media that containscrystal violetdye orvery high conc.ofbile salts (aka ___________)•Abundantgrowthat ________ hr.•Motility?

Back 25

•Grow on any nutrientmedia that contains peptone•Inhibitedby media that containscrystal violetdye orvery high conc.ofbile salts (aka MacConkey)•Abundantgrowthat 18-24 hr.•Non-motile

Front 26

Staphylococcus•Therearemany species (morethan 30).

Thereare 4 major species:

Back 26

aureus

epidermidis

saprophyticus

lugdunensis

Front 27

•MacConkey Agar is selective for what

Back 27

selective for gram negative

Front 28

Staphylococci on gram stain:

Back 28

Gram stain:GPC in singles, pairs,tetrads and/orclusters

Front 29

Catalase test principle:

Staph and micrococcus-

strep and enterococcus-

Back 29

Catalase(enzyme)convertshydrogen peroxide(H2O2) into waterand oxygen.

Staphylococcus and Micrococcus are typicallycatalase positive

Streptococcus and Enterococcus speciesare typically negative. Enterococcus can be a weak positive, but is stillconsidered negative.

Front 30

Tests to Identify Staph sp.

Back 30

Coagulase (slide, tube, latex),

Mannitol Salt agar

Novobiocin Susceptibility

PYR hydrolysis

Rapid Ornithine (decarboxylaseactivity)

DNase

Front 31

Identification methods used to differentiate the genus Micrococcus from the genus Staphylococcus:

Back 31

Modified Oxidase

Oxidative-Fermatative Test

Bacitracin (Taxo A)

Lysostaphin susceptibility

Front 32

Coagulase Test (Coagulase is an enzymethatconverts solublefibrinogen into insoluble fibrin)

Slide measures...

Tube measures...

Latex measures...

Back 32

Slide – measures bound coagulase (clumpingfactor) which is attached to the cellwallsof the bacteria

Tube – measures free coagulase (extracellular enzyme)

Latex – measures protein A (and bound coagulase)

Front 33

Negative slide coagulase reactions must be confirmed by what test?

Back 33

Negative slide reactions must be confirmed by the tube test.

Front 34

What temp is the tube coat test incubated at?

Back 34

Incubate at 35-37C. Observe at 2 – 4 hours for the formationof a clot (positivereaction).

Front 35

In the latex agglutination test, what are the latex particles coated with?

Back 35

Latex particlescoatedwithhuman fibrinogen fordetection ofclumping factorand coatedwithspecific IgG for detection of protein A.

Front 36

Mannitolsalt agar (MSA)is a selectiveand differentialmedium used to isolate ______________.

If it grows and can ferment what color is the media around the colonies?

Back 36

Mannitolsalt agar (MSA)is a selectiveand differentialmedium used to isolate Staphylococcusaureus.

yellow

Front 37

This test is used todifferentiate Staphylococcus saprophyticus (resistant)from other coagulase negativeStaphylococcus (susceptible)fromorganisms isolatedfrom urine specimens.

what media is used?

Back 37

NovobiocinSusceptibility

done on BA

Front 38

PYR test CAN BE used to differentiate S.aureus from S.lugdenensis

What are the results of this test??

Back 38

S. aureus = negative

S. lugdenensis = positive (pink to cherry-red color)

Front 39

Rapid Ornithine (decarboxylaseactivity) is used to detect which organism?

Back 39

Used to identify Staphylococcus lugdunensis

Staphylococcus lugdunensisis rapid ornithine positive• Other Staphylococcus species are negative (except rare strains of S. epidermidis)

Front 40

The DNase test is used to identify which Staph species

Back 40

Staphylococcus aureusgivesa positive DNasereaction (show by clearinga dye in the medium.TheDNase producedby Staphylococcusaureus isalso thermostable.

Front 41

What is the modified oxidase test "looking for"?

Back 41

Used todifferentiate Micrococcus from Staphylococcus.

Test is lookingfor thepresence of cytochrome c enzymes

Test uses Microdase Disks. (Micrococcus: Pos=dark blue... Staph=negative)

Front 42

Oxidative-FermentativeTest

Results for Staph and Micrococcus

Back 42

Staphylococcus ferments glucose

Micrococcus oxidizes glucose/nonsaccharolytic

Fermentative– acid productionin both tubes.Oxidative– acid productionin the aerobictube, no acid productionin the anaerobictube.

Nonsaccharolyticor Asaccharolytic– no acid productionin either tube.

Front 43

Bacitracin (Taxo A)

Results for Micrococcus and Staph

Back 43

Susceptible– zone of inhibition ≥10mm.(Micrococcus)

Resistant– no zone of inhibition.(Staphylococcus)

Front 44

Results from Lysostaphin susceptibility testing

Back 44

Staph=lysed

Micrococcus= not lysed

Front 45

Which staph may cause a double zone of hemolysis

Back 45

Staph aureus

Most strains are beta hemolytic (not all strains)and may show a double zone of hemolysis.

Front 46

Pseudomembranous enterocolitis

Back 46

Staph aureus entertotoxin

Front 47

Exfoliative toxin (or epidermolytic toxin)

Cause the epidermal layer of skin to slough off

Back 47

staphylococcal scalded skin syndrome

Front 48

Toxic Shock Syndrome Toxin 1 (TSST-1)

Back 48

Staph aureus exotoxin

Front 49

Panton-Valentine leukocidin (PVL)

Back 49

Staph aureus Cytolytic toxin

lethal to WBCs– Contributes to the spread of infection by suppressingphagocytosis– Causes severe cutaneous infections and necrotizingpneumonia

Front 50

Organisms that produce _________________ can form protective barriers of fibrin around themselves,making themselves highly resistant to phagocytosis, other immune responses, and some otherantimicrobial agents

Back 50

coagulase

Front 51

Responsible for clotbreakdown in the tube coagulase test

Back 51

Staph aureus enzyme: Fibrinolysin (staphylokinase)

Front 52

This staph aureus extracellular enzyme hydrolyzes acid in connective tissue allowing spread of infection

Back 52

• Hyaluronidase

Front 53

This staph aureus extracellular enzyme confers resistance against penicillin

Back 53

Beta-lactamse

Front 54

this staph aureus enzyme Allows colonization by acting on fass present on the surface of the skin.

Back 54

Lipase

Front 55

Which staph aureus virulence factor is found in the cell wall, binds to Fc part of IgG and blocks phagocytosis

Back 55

Protein A

Front 56

Whats up with pus?

Back 56

Accumulationof pus-mix of active and inactive neutrophils,bacterial cells and extravascular fluid

Front 57

Staph aureus skin infections:

Back 57

Folliculitis, Boils (furuncles) and carbuncles (mass of furuncles)

Front 58

The pustules of staph are different from the pustules of strep in what way?

Back 58

Staph = larger with redness

Front 59

Scalded skin syndrome is caused by which organism?

Toxin?

Another name?

Back 59

S. aureus

Exfoliative/epidermolytic toxin

Ritter Disease

Front 60

Food poisoning from Staph aureus is most commonly caused by which toxins

Back 60

enterotoxin A and D

Heat stable toxins that are not destroyed byreheating foods

Front 61

Common food culprits of Staph aureus poisonin'

Symptoms

Back 61

potato salad, processed meats,custards, bakery goods

Cause vomiting and diarrhea 2-8 hrs. after ingestion– Lack fever and symptoms usually resolve within 24to 48 hrs

Front 62

antibiotic-associated colitis and occurswhen the normal flora of the large bowel is altered

Back 62

Staph aureusPseudomembranous enterocolitis

Front 63

Common Antibiotics prescribed for Staph aureus

Back 63

methicillin, oxacillin, nafcillin (resistant to enzyme penicillinase)

Front 64

gene responsible for altering penicillin binding proteins

Back 64

MecA

Front 65

drug of choice for MRSA

Back 65

Vancomycin

Front 66

Resistant strains of MRSA grow: more slowly/fasterly?

Back 66

Resistant strains grow more slowly

Front 67

When performing antimicrobial testing optimaldetection of MRSA is obtained by:

Back 67

direct inoculation

24H cooler incubation (30-35C)

Neutral pH (7.0-7.4)

media with 2% NaCl

Front 68

Gold Standard for MRSA detection

Back 68

Nucleic acid probes or PCR amplification fordetection of mecA gene

Front 69

Other Methods to Detect MRSA :

A _________________ disk has been proven to be a good inducerof the mecA gene which is responsible for methicillinresistance

Back 69

– Cefoxitin Disk (30 ug)

Due to heterotypic resistance phenotype some MRSAmay not be detected by MIC microdilution methods

Front 70

VRSA=

VISA=

Back 70

VRSA= vancomycin resistant Staphylococcus aureus

VISA= vancomycin intermediate Saphylococcus aureus

Front 71

Differential and Screening media used forMRSA:

Back 71

CHROMagar or Spectra MRSA agar– Selective media with specificchromogenic substrates– Cefoxitin is incorporated in the CHROMagar to induce the mecA gene andallow for increased detection

Mueller-Hinton agar with 4% NaCl and 6 ug Oxacillin(Oxacillin Screen agar)

Front 72

Infections with these organisms are predominantly hospital acquired,associated with instrumentation procedures, immunosuppressivetherapy and immunocompromised patients.

Back 72

Coagulase Negative Staphylococci

Front 73

Most frequently isolated Coagulase Negative Staphylococcus inclinical lab is

Back 73

Staph. epidermidis.

Front 74

Colony morphology of Staph epidermidis.

Back 74

Opaque, smooth, raised, entire (smooth orregular border), gray-white, non-hemolytic

Front 75

Strains of staph epidermidis are able to inhibit immune functions including theaction of lymphocytes and neutrophils (opsonization and phagocytosis) because of this:

Back 75

Extracellular Slime substance

Front 76

Staphylococcus epidermidisInfections:

Back 76

Subacute bacterial endocarditis (SBE)

Meningitis

Bacteremia/septicemia

Wound infections

Urinary tract infections

Post-operative surgical infections

Front 77

______________________ is generally more resistant than Staphylococcus aureus

treatment:

Back 77

Staphylococcus epidermidis

Methicillin (oxacillin)Vancomycin for methicillin resistant strains

Front 78

Staphylococcus saprophyticus colony morph

Back 78

Opaque, smooth, raised,entire,glossy white-yellow, non-hemolytic.Some strains look bright white.

Front 79

A coagulase negative Staphylococcus that is resistant to Novobiocinis indictative of _______________________________ in urinary tract cultures and nofurther identification is usually necessary.

Back 79

S. saprophyticus

Front 80

2nd to Escherichiacoli as the cause of UTI in young girls

Back 80

Staphylococcus saprophyticus

treatment: nitrofurantoin,trimethoprim/sulfa, fluoroquinolones

Front 81

Staphylococcus lugdunensis colony morph

Back 81

Usually opaque, very white, non-hemolytic,canbe beta hemolytic but developslater

Front 82

Which staph/micrococcus organism is positive for rapid ornithine?

Back 82

Staphylococcus lugdunensis

Front 83

Besides the coagulase test, what test could you do to differentiate S. aureus from S. lugdunensis?

Back 83

PYR

S. lug = positive

s. aureus = negative

Front 84

Staphylococcus lugdunensis

Clinical significance:

Back 84

Endocarditis, septicemia, meningitis, skin and soft tissueinfections, urinary tract infections, and septic shock

May possess mecA gene

Front 85

D test

Back 85

Measures induceable resistance to clindamycin

– Use erythromycin and clindamycin disks• Growth between disks but not on side of clindamycindisk– Inducible resistance

Front 86

Micrococcus oxygen requirements:

Back 86

Obligate aerobe, usually will not grow anaerobically

Remember: staph are facultative anaerobes

Front 87

Gram stain/morphology of Micrococcus:

Back 87

LargeGPC in pairs, tetrads,or masses

Front 88

Colony morphology of Micrococcus

Back 88

Smooth, raised,opaquewhite, bright yellow, pink

Front 89

Some animal isolates (S. intermedius, S. hyicus, and S.delphini) may be tube coagulase_____________ and should beconsidered in wounds involving animal bites.

Back 89

POSITIVE

Front 90

Coagulase negative species S. lugdunensis and S.schleiferi produce clumping factor so:

Coagulase test:

Latex agglutinationtests:

Tubecoagulase test:

Back 90

Coagulase test: POSITIVE

Latex agglutination tests: POSITIVE

Tube coagulase test: NEGATIVE

Front 91

THIS organism shows strong adherence to the agar surface when you try to pick up thecolony due to the presence of a capsule (colony will stand up like eggwhites if teased with a stick)

Back 91

Stomatococcus (Rothia)mucilanginosus

Encapsulated GPC that is part of normal human respiratory flora

Front 92

The modified oxidase/bacitracin susceptibility testing is typically only done when...

Back 92

the colonies look yellow. This is b/c you may suspect Micrococcus which are:

Mod. Oxidase: positive

Bacitracin: Susceptible

Front 93

This is most likely which organism(s)?

Back 93

STREPTOCOCCUS, ENTEROCOCCUS,AND RELATED ORGANISMS

GPC in pairs and chains (can be encapsulated)

Front 94

General Characteristics ofStreptococcus and Enterococcus:

O2/CO2 requirements:

Media:

Back 94

Most behave as facultative anaerobes

May need increased CO2 togrow

Typically required enriched media (BA) for growth.

Front 95

Brown's classification is based on...

Lancefield is based on...

Back 95

Browns: Hemolytic pattern

Lancefield: based on specific cell wall polysaccharide antigens

Front 96

Lancefield classification is used for which group of organisms?

Back 96

Strep

Front 97

Hemolytic patterns:

alpha-

beta-

gamma-

Back 97

alpha: incomplete or partial lysis (greening)

beta: complete lysis(colorless, clearzone)

gamma: non-hemolytic

Front 98

Hemolytic Patterns of Strep:

Group A:

Group B:

Group C:

Group D:

Group F:

Group G:

Back 98

Hemolytic Patterns of Strep:

Group A: large zone, strong

Group B: narrow zone, weakGroup

C: large zone, strong

Group D: variable (may be alpha, beta, or gamma)

Group F: narrow zone, weak

Group G: large zone, strong

Front 99

Which organisms belong to these groups?

Group A:

Group B:

Group C:

Group D:

Back 99

Group A: S. pyogenes

Group B: S. agalactiae

Group C: S. equisimilis, S. equi, S. zooepidemicus

Group D: Enterococcus sp., Strep bovis, Strep equinus:

Strep pneumoniae: none

Front 100

Bacitracin (Taxo A) susceptibilityUsed to identify group __ streptococci

Back 100

Group A

S. pyogenes (SUSCEPTIBLE)

Front 101

Which test is often used wtih Taxo A to identify group A and group B strep?

Back 101

Sulfamethoxazole-Trimethoprim (SXT)Susceptibilty

Group A: resistant

Group B: resistant

Group C, D, F, G: susceptible (any zone)

Front 102

CAMP test principle:

identifies:

Back 102

CAMP factor is a diffusible compound that produces a characteristic “arrowhead” pattern when streakedperpendicular to beta hemolytic Staph aureus.

Group B organism

Front 103

Bile Esculin Agar is used to identify

Back 103

group D streptococci (and Enterococcus.)

Positive: growth and medium turns black(minimum of 50% of medium)

Front 104

6.5% NaCl BrothUsed to differentiate

Back 104

Used to differentiate group D enterococci from group D nonenterococci

POSITIVE= Group D Enterococcus sp.

NEGATIVE=Group D not Enterococcus sp.

Front 105

PYRase test can be used to differentiate Enterococcus and Group AStreptococcus from other organisms

Back 105

(Tests for the ability to hydrolyze the substrate L-pyrrolidonyl-alphanapthylamide(PYR)

Enterococcus or Group A Strep: positive

Other GPC, catalase negative organisms: negative

Front 106

Another name for the Optochin test is:

What differentiation is it used for?

Incubation:

Back 106

Taxo P: Used to differentiate Streptococcus pneumoniae from other alpha hemolyticStreptococcus.

S. pneumoniae=SUSCEPTIBLE

Incubated in CO2

Front 107

Bile Solubility is also used to differentiate Streptococcus pneumoniae from Streptococcus viridans

Results:

Back 107

Strep pneumoniae: dissolves (positive)

viridans Strep: doesnt dissolve (neg)

Front 108

The HippurateTest is used to differentiate which streps from other groups?

Back 108

Group B!

Group B Streptococcus: positive

Group A, C, D, F, and G: negative

Front 109

What does the LAP test help in differentiating....?

Back 109

Helps differentiate Aerococcus viridans (negative) and Leuconostoc(negative) from other Streps and Strep-like organismsUsed in combination with PYR and EsculinTest for leucine aminopeptidase which is able to hydrolyze peptidebonds adjacent to a free amino acid group

Front 110

The Latex Agglutination (Streptex) is used for whhhhhhat

Back 110

Used to differentiate Streptococcus into Group A, B, C, D, F, or G.• Test is based on looking for the particular carbohydrate group that isunique to each group.• Test uses latex particles coated with antibodies to the particlecarbohydrate group. Typically, the organism is placed in a solution ofan extract (acid) to expose the carbohydrate

Front 111

Beta hemolytic Streptococci:

Back 111

Group A Strep (Streptococcus pyogenes)

Group B Strep (Streptococcus agalactiae)

Groups C, F, and G Strep..

Front 112

Alpha hemolytic Strep:

Back 112

Streptococcus pneumoniae(pneumococci)

Viridans group (S. salivarius, S. mitis, S.anginosus, S. sanguinus, S. mutans, S.bovis)

Front 113

Gamma hemolytic Streptococci:

Back 113

Group D Strep

Front 114

Group D Streptococcus NOT Enterococcus:

Back 114

S. bovis

Front 115

Group A Strep colony morph:

Back 115

Small, glossy, transparent, smooth, large zone beta hemolysis

Front 116

Hey girl - you got this.

Back 116

XOXO,

Ryan

Front 117

Group A Strep Identification:

– Immunologic tests to detect previous infection

Back 117

PYR = POSTIVE

BAcitracin = Sensitive

SXT = resisitant

Anti-Streptolysin O (ASO), DNase B (most specific), Antistreptokinase,and anti- hyaluronidase titers

Front 118

Group A Streptococcus(Streptococcus pyogenes)Major virulence factor, found in organism’s cell wall:

Back 118

M Protein

Front 119

Which toxin causes the rash in scarlet fever?

Back 119

Streptococcal pyrogenic exotoxins (Spes)• previously called Erythrogenic toxin

Front 120

Group A Streptococcus(Streptococcus pyogenes) hemolysins:

Back 120

Streptolysin S:Non-antigenic, oxygen stable, responsible for surface hemolysis.

Streptolysin O:Antigenic, oxygen labile, produced mainly by group A streptococci (also C andG), responsible for hemolysis in reduced O2 environments.

Front 121

The oval-shaped areas of clearing around the stab marks in the picture are caused by which toxin?

Back 121

Streptolysin O

Front 122

Streptococcal pharyngitis (sore throat):

Most common infection caused by__________

Back 122

Group A Strep

Diagnosed by antigen testing and/or culture (sheep blood agarshould be stabbed to check for SLO)

Front 123

Erysipelas: what is that?

Back 123

Skin and lymphatics under skin infected by Group AStrep

Swollen, red, tender area

Infection through scratch on skin surface

Culture watery blisters oradvanced edge of spreadinginfection

Front 124

Back 124

Impetigo

Localized blisters of superficialskin

Contagious over own body andperson-to-person

(Strep pyogenes)

Front 125

Back 125

Cellulitis• Develop following deeper invasionby Group A Strep• Serious, life-threatening infection,can be accompanied by bacteremiaorsepsis• Skin infection involving deep tissues

Front 126

Describe this suppurative (pus-producing) disease:

Back 126

Scarlet feverIf infecting Group A Strep produces pyrogenic exotoxinsSpes (erythrogenic toxin), rash occurs unless patienthas antitoxic immunity

Rash not caused by organism directly

Front 127

____________ is considered the most common cause of necrotizing fasciitis.

Back 127

Group A strep

Front 128

Non-suppurativeGroup A Strepto0coccus(Streptococcus pyogenes) diseases:

Back 128

Post-streptococcalsequelae: Rheumatic feveror Acute glomerulonephritis

Front 129

Strep Group A:The most serious “delayed sequelae” type disease as it results indamage to the heart muscle and its valves

Back 129

Rheumatic feverOccurs 2-3 weeks after a throat Group A Strep infection• Patient has high ASO titer (also anti-hyaluronidase and/or anti-DNase)• Symptoms include fever, malaise, polyarthritis and inflammation of allparts of the heart leading to thick, deformed valves and perivasculargranulomas in the heartmuscle• Exact mechanism not known (thought to be a cross-reaction betweenstrep antibodies and heart tissue)

Front 130

Group B Streptococcus(Streptococcus agalactiae)

Colony morph:

Back 130

Flat, glossy, grayish-white, small zone beta hemolysis (can be gamma)

Front 131

Group B Streptococcus (Streptococcus agalactiae) "identification":

Back 131

• PYR = negative

• Sodium hippurate = positive

CAMP = positive

Front 132

Group B Streptococcus(Streptococcus agalactiae)• Invasive disease in the newborn

Back 132

Early-onset (less than 7 days old): most common, caused byvertical transmission from the mother.» Infection often presents as a pneumonia or meningitiswith bacteremia» Recommend all pregnant women be screened for group Bstreptococci at 35-37 weeks gestation– Late-onset (at least 7 days old): usually presents as meningitis

Front 133

GBS screening for pregnant women

Back 133

Todd-Hewitt and LIM broth

Strep B Carrot broth is available

Front 134

Group B Streptococcus(Streptococcus agalactiae)Disease states

Back 134

Adults– Vaginitis, postpartum fever and sepsis, endocarditis, urinarytract infections, upper respiratory disease, osteomyelitis, andwound infections

Front 135

Groups C, F, and G StreptococcusDisease states

Back 135

Occasionally implicated in bacteremia, endocarditis, woundinfections, meningitis, pneumonia, genitourinary tractinfections, post-partum sepsis and severe pharyngitis (especiallyGroup C Strep)

Front 136

Streptococcus pneumoniae(pneumococci) Colonial morphology

Back 136

Alpha hemolytic(checker or mucoid colonies)• Enzyme causes autolysis of cells, producedupon prolonged incubation which causes the sunken center

Front 137

Which strep is susceptible to optochin?

Back 137

s. pneumoniae

Front 138

Back 138

Streptococcus pneumoniae(pneumococci)

Lancet shaped cocci in pairs– seen best in clinical and broth specimens

Front 139

Most common cause of community acquiredbacterial pneumonia

Back 139

Streptococcus pneumoniae (pneumococci)

Front 140

Whcih strep organism is showing increased resistance to Penicillin G?

Back 140

Streptococcus pneumoniae(pneumococci)

*Key point *: A disk diffusion susceptibility testmust be performed using an oxacillin (1 ug) KBdisk to check for penicillin susceptibility. Theisolate is tested on Mueller-Hinton agar with 5%sheep’s blood and incubated in CO2.

Front 141

Viridans group (S. salivarius group, S. mitis group, S.anginosus group, S. sanguinus, S. mutans group, S.bovis group)

Colonial morphology :

Back 141

Tiny, gray, domed, alpha hemolysis (can vary in morphologies)– Basically, any alpha Strep that is not S. pneumoniae or Enterococcus is a SVG

Front 142

Viridans group (S. salivarius group, S. mitis group, S.anginosus group, S. sanguinus, S. mutans group, S.bovis group)

IDENTIFICATION

Back 142

Front 143

Most common cause of subacute bacterialendocarditis

Back 143

Viridans group (S. salivarius group, S. mitis group, S.anginosus group, S. mutans group, S. bovis group)

Front 144

Which strep Will grow in 40% bile and hydrolyzes esculin.

Back 144

Group D Streptococcus

Front 145

Group D Streptococcus is divided into two subgroups:

Back 145

Enterococcus sp.

non-Enterococcus

Front 146

S. bovis belongs to which group(s)

Back 146

Strep bovis is a Group D non-Enterococcus

Some people think they should be in the Viridans group (which is pretty much a group that is the catch-all for all strep that AREN'T beta-hemolytic streptococci, enterococci, or pneumococci)

Front 147

endocarditis from which organism is highly correlatedwith gastrointestinal carcinoma

Back 147

Group D Strep NOT Enterococcus (S.bovis)

Front 148

Important to distinguish Group D non-enterococcus from Enterococcus because... Group Dis sensitive to what?

Back 148

penicillin

Front 149

Enterococcus consists of 2 major species:

Back 149

faecalis (most common; 80% – 85%)

faecium (10%)

Front 150

Which of the following is more resistant to antibiotics:

Enterococcus

Group D Strep

Back 150

Enterococcus!

Front 151

Other Strep-like bacteria:

Just know that these exist... and that you can do tests to differentiate

Back 151

Aerococcus: opportunistic

Gamella:Normal flora of upper respiratory tract and GI tract

Lactococcus: dairy processing

Leuconostoc: sauerkraut

Pediococcus: Group D antigen, grows @45C

Abiotrophia: Requires Vitamin B6 or pyridoxal to grow, satellite growth aroundStaphylococcus aureus

Front 152

Back 152