Streptococcus

Front 1

Genus streptococcus

Back 1

a. Gram positive cocci in pairs or chains
b. Facultative and capnophilic
c. Fastidious

Front 2

Serology of strep

Back 2

a. Lancefield groupings
b. A-W

Front 3

Strep hemolysis

Back 3

a. β
b. α
c. γ

Front 4

S. pyogenes

Back 4

a. Associated with pyogenic infections
b. Catalase-negative
c. β hemolysis
d. Requires enriched medium (blood and serum)

Front 5

S. pyogenes epidemiology

Back 5

a. Asymptomatic URT and transient skin colonization
b. Person to person spread by respiratory droplets
c. Crowding facilitates spread
d. .5 deaths/yr due to GAS infections

Front 6

Patients with soft-tissue infections and bacteremia with s. progenies

Back 6

i. TSS

Front 7

5-15 y/o risk

Back 7

i. Pharyngitis

Front 8

2/5 y/o with poor hygiene

Back 8

i. Pyoderma

Front 9

Seasonal risk

Back 9

i. Pharyngitis--winter
ii. Pyoderma--summer

Front 10

S. pyogenes virulence

Back 10

a. Capsulated
b. LTA
c. M protein
d. M-like protein
e. F protein

Front 11

M-proteins in s. pyogenes

Back 11

a. >120 serotypes
b. Anchored in cell wall and extends to surface
c. Phagocytic resistance neutralized by M-protein antibody
d. Plasma fibrinogens binds to M-proteins

Front 12

Plasma fibrinogens binding to M-proteins causes....

Back 12

i. A prevention of complement activation and opsonization

Front 13

Increase of M-antibodies

Back 13

i. Protection from only that serotype

Front 14

S. pyogenes pharyngitis

Back 14

a. Strep throat
b. Primarily in 5-15y/o age group
c. Adults and very young also susceptible
d. Spreads via respiratory droplets and close contact

Front 15

Peak of s. pyogenes pharyngitis

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i. Winter

Front 16

Incubation period of s. pyogenes

Back 16

i. 1-4 days

Front 17

Symptoms of s. pyogenes pharyngitis

Back 17

i. Mild throat discomfort to severe swelling of pharyngeal mucosa with exudate

Front 18

Suppurative complications of s. pyogenes

Back 18

i. Peritonsillar or retropharyngeal abscess
ii. Rheumatic fever

Front 19

Non-suppurative complications of s. pyogenes

Back 19

i. Acute glomerular nephritis
ii. Suppuration rare due to timely antibiotic treatment

Front 20

What toxins produce scarlet fever?

Back 20

1. Pyrogenic exotoxins A, B, and C

Front 21

Toxin spread in scarlet fever

Back 21

1. Through the blood
2. Localizes in the skin
3. Induce a diffuse erythematous rash on upper chest

Front 22

Initial presentation of scarlet fever

Back 22

1. Tongue initially furred and red later
2. Rash spreads to extremities
3. Rash disappears in 5-7 days followed by desquamation
4. Disease is now rare

Front 23

Scarlet fever and subsequent s. pyogenes infection

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1. Rash not serious in scarlet fever, but signals infection by a harmful S. pyogenes

Front 24

Scarlet fever rash

Back 24

1. Discrete
2. Pinhead-sized
3. Desquamation follows

Front 25

Streptococcal impetigo/pyoderma

Back 25

i. More common in summer
ii. Most common in children w/ poor hygiene
iii. Skin colonization precedes clinical infection
iv. Minor trauma introduces GAS into skin

Front 26

Usual site of impetigo/pyoderma

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1. Around nose and mouth
2. Legs

Front 27

Progression of impetigo/pydoerma

Back 27

1. Vesicle→ pustule→ ruptures and crusts over
2. Lesion usually not painful and patients do not appear ill

Front 28

Culture of lesion in streptococcal impetigo/pyoderma

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1. Yields S. aureus and S. pyogenes

Front 29

Cellulitis

Back 29

i. Infection involving skin and subcutaneous tissues
ii. Infection due to traumatic/surgical wound or insect bite
iii. Often no entry site is apparent

Front 30

Ersyipelas

Back 30

i. A form of cellulitis
ii. Bright and red appearance of skin
iii. Usually on malar area of face
iv. Extends over bridge of nose to contralateral malar region
v. “Butterfly rash”

Front 31

Necrotizing fasciitis

Back 31

i. GAS responsible for ~60% of cases
ii. Starts like cellulitis→ gangrene, bullaes, and systemic signs
iii. Requires extensive debridement and antibiotic treatment
iv. Obstructed blood supply along the fascial planes

Front 32

Extensive necrosis

Back 32

1. Requires surgical exploration

Front 33

What is another name for necrotizing fasciitis?

Back 33

1. Hemolytic streptococcal gangrene

Front 34

Streptococcal TSS

Back 34

i. Likely in patients bacteremic with GAS

Front 35

Bacteremia causes....

Back 35

1. Pharyngitis→ rare
2. Cellulitis→ occasional
3. NF→ always

Front 36

streptococcal toxins in TSS

Back 36

1. Always involved
2. SpeA and SpeC-- super antigens

Front 37

Symptoms of streptococcal TSS

Back 37

1. Fever
2. Malaise
3. HT
4. Multiple organ failure

Front 38

Acute rheumatic fever and rheumatic heart disease

Back 38

i. 1-3 wk after acute illness
ii. Almost exclusively after a URT infection (pharyngitis)
iii. Less common in developed countries

Front 39

Rheumatogenic GAS

Back 39

1. Encapsulated and rich in M proteins

Front 40

Presentation of rheumatogenic GAS

Back 40

1. S/C nodules
2. Arthralgia
3. Frank arthritis

Front 41

Ig and rheumatogenic GAS

Back 41

1. Anti-M IgG cross-react with heart proteins
2. Produce pancarditis

Front 42

Prevention of rheumatogenic GAS

Back 42

1. Antibiotic prophylaxis needed to prevent subsequent GAS infection

Front 43

Acute glomerulonephritis

Back 43

i. Can be seen after pharyngitis and also after skin infections
ii. Only 4-5 M strains cause AGN, recurrences are unlikely
iii. Ag-Ab complexes on glomerular basement membrane
iv. Glomerular capillaries are filled with monocytes and PMNs

Front 44

Antibiotic prophylaxis for acute glomerulonephritis

Back 44

1. Not recommended

Front 45

Symptoms of AGN

Back 45

1. Acute inflammation
2. Hypertension
3. Hematuria
4. Proteinuria

Front 46

Identification of s. pyogenes

Back 46

1. Chains of cocci
2. Β-hemolytic
3. Catalase-negative

Front 47

PYR test in s. pyogenes

Back 47

1. Only streptococci that gives a positive test
2. Forms pink to cherry-red pigment

Front 48

A disk in s. pyogenes

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1. Bacitracin
2. S pyogenes is sensitive but S agalactiae is resistant

Front 49

P disk in s. pyogenes

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1. Optochin
2. Most viridian streptococci are α hemolytic
3. S. pneumoniae- sensitive
4. Other viridans-resistant

Front 50

Two immunogenic toxins of s. pyogenes

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1. Streptolyisn O
2. DNase B

Front 51

Group B strep

Back 51

a. Streptococcus agalactiae

Front 52

S. agalactiae characteristics

Back 52

1. Gram positive cocci
2. Long chains
3. β hemolytic

Front 53

S. agalactiae epidemiology

Back 53

1. Native to female urogenital tract and rectum
2. Women with genital colonization--risk for postpartum sepsis
3. Babies acquire from other or babies in nursery

Front 54

Nine capsular polysaccharide types of s. agalactiae

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a. Ia, Ib, II-VIII

Front 55

Most commonly capsular polysaccharides associated with disease

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i. Ia
ii. III
iii. V

Front 56

Affects of GBS on fetus

Back 56

1. Genital colonization increases risk of premature birth
2. Premature infants are at greater risk of disease

Front 57

GBS in men and non-pregnant women

Back 57

1. Disease usually in older and IC
2. Bacteremia, pneumonia, bone, skin and soft tissue infections
3. High mortality due to IC

Front 58

GBS in pregnant women

Back 58

1. UTI during and immediately after pregnancy

Front 59

Puerperal sepsis in GBS

Back 59

a. Serious septiciemia during or shortly after childbirth
b. Rare due to improved hygiene during delivery

Front 60

GBS disease in newborns

Back 60

1. Major cause of neonatal meningitis
2. Acquired by aspiration of infected amniotic fluid
3. Few alveolar Mψ, poor PMN chemotaxis and phagocytosis
4. Low complement levels which are needed for GBS killing

Front 61

Early-onset GBS disease in newborns

Back 61

a. >5% motality due to better dx and supportive care
b. Clinical presentation
i. Bacteremia, pneumonia, and meningitis

Front 62

Late-onset GBS disease in newborns

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a. Acquired from infected mother or nosocomial
b. Bacteremia with meningitis

Front 63

Identification of s. agalactiae

Back 63

i. Catalase-negative
ii. β hemolytic
iii. Coccus

Front 64

Biochemical tests for s. agalactiae

Back 64

1. Hydrolysis of sodium hippurate (99% positive)
2. Hydrolysis of bile esculin (99-100% positive)
3. Bacitracin susceptibility (92% resistant)
4. CAMP test (98-100% positive)

Front 65

CAMP test for s. agalactiae

Back 65

1. Christie, Atkins, Munch, Petersen test
2. CAMP factor is a phospholipase
3. Causes synergistic hemolysis with S. aureus β-lysin

Front 66

Prevention of s. agalactiae

Back 66

i. Screen anogenital region @ 35-37 weeks of pregnancy
ii. Chemoprophylaxis for culture positive cases
iii. Treat women with history of GBS+ irrespective of test result

Front 67

Viridans streptococci

Back 67

a. Non-pyogenic
b. 5 groups
c. *Mitis, *anginosus, *salivarius, mutans, bovis
d. *-- Core of group

Front 68

Prevalence of viridans streptococci

Back 68

i. Oral cavity
ii. URT
iii. Female genital tract
iv. Can cause cavities

Front 69

Viridans spread to blood

Back 69

i. Through disruption of oral mucosa

Front 70

Important viridans

Back 70

i. S. mitis
ii. s. mutans
iii. s. salivarius
iv. s. sanguis

Front 71

Viridis

Back 71

i. Green
ii. Produce a green pigment on blood agar

Front 72

Mitis group

Back 72

1. Includes s. pneumonia and 12 other species

Front 73

S. pneumoniae characteristics

Back 73

a. Gram positive coccus (lancet shaped)
b. Diplococci (pairs)
c. Fastidious
d. Capsulated
e. Capnophilic
f. α hemolytic
g. Bile salt susceptible

Front 74

s. pneumoniae epidemiology

Back 74

i. Colonizes nasopharynx
ii. 5-10% of adults and 20-40% of children
iii. Mostly endogenous spread
iv. URT to middle ear, sinuses, meninges, lungs, and blood

Front 75

Colonization and migration of s. pneumoniae

Back 75

i. Colonization of URT is mediated by surface adhesins

Front 76

sIgA and s. pneumoniae

Back 76

i. SIgA trap bacteria in mucus and prevent migration to lower LRT
ii. Produce sIGA protease and pneumolysin (ply)

Front 77

Ply

Back 77

1. Kills ciliated epithelial cells and phagocytes
2. Lysis of host cells causes edema, hemorrhage, bacterial growth
3. Helps in penetration through epithelium into interstitium and blood

Front 78

S. pneumoniae removed from airways by...

Back 78

1. Ciliated epithelial cells

Front 79

Capsule of s. pneumoniae

Back 79

i. Primary virulence factor
ii. Non-encapsulated strains are almost harmless
iii. Inhibits phagocytosis and complement
iv. >90 serotypes

Front 80

Vaccines for s. pneumoniae

Back 80

1. Mixture of capsular polysaccharides

Front 81

Disease of s. pneumoniae

Back 81

i. Occur worldwide
ii. Frequently seen in co-infection with influenza

Front 82

Three major clinical diseases of s. pneumoniae

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i. Pneumonia
ii. Meningitis
iii. Otitis media

Front 83

S. pneumoniae pneumonia

Back 83

i. Often preceded by viral illness
ii. Viruses up-regulate adhesion factors in respiratory epithelium

Front 84

PG and TA in pneumonia

Back 84

1. PG and TA induce invasion
2. PG/TA also induce inflammatory cytokines (IL1, IL6, TN F)

Front 85

Symptoms of s. pneumoniae pneumonia

Back 85

1. Acute onset, high fever with rigors, productive cough
2. Pleural pain, dyspnea, tachypnea, tachycardia, sweats
3. PMNs and lance-shaped diplococcic in rusty sputum
4. Rusty sputum as blood leaks from capillaries

Front 86

Localization of pneumonia

Back 86

1. Only affects a section/lobe
2. No significant protease-- seldom destroys parenchyma
3. Consolidation is less obvious in dehydrated patients

Front 87

Otitis media symptoms

Back 87

1. Severe and continuous earache often with fever of 39C or more
2. Pain and fever more common than OM caused by other bacteria
3. Rare cases-- may spread from middle ear to cause meningitis

Front 88

Bacterial pathogens in OM

Back 88

1. Negative culture-- 33.7%
2. S. pneumonia-- 29.4%
3. Moraxella catarrhalis--25.2%
4. H. influenzae-- 20.5%

Front 89

Meningitis

Back 89

i. Most common cause in children and adults in US
ii. Severe neurological defects in survivors

Front 90

Predisposing conditions to meningitis

Back 90

1. Pneumonia
2. OM

Front 91

Fatality compared to other bacterial meningitis

Back 91

1. Higher

Front 92

Bacteremia/endocarditis from s. pneumoniae

Back 92

i. ~30% pneumonia and 80% meningitis patients are bacteremic
ii. Sub-acute endocarditis
iii. Common in those with previous damaged heart valves

Front 93

Identification of s. pneumoniae

Back 93

i. α hemolytic
ii. Lancet-shaped
iii. Gram positive
iv. Diplococcic
v. Catalase negative
vi. Bile soluble
vii. Optochin-sensitive
viii. TA in urine

Front 94

Enterococcus characteristics

Back 94

i. E. faecalis predominates
ii. Gram positive cocci (pairs and short chains)
iii. High salt, bile, temp, and antibiotic resistance

Front 95

Enterococcus epidemiology

Back 95

i. Enteric pathogen, can also colonize the GUT
ii. Most infections are endogenous
iii. Frequent cause of nosocomial infections
iv. Cross-infection in nosocomial settings

Front 96

Enterococcus virulence

Back 96

i. Many secreted factors, adhesins, and a dynamic genome
ii. Use of avoparcin-- a GP/growth promoter in animal husbandry
iii. Proliferaiton after antibiotic use--especially in those that target anaerobes/gram negative rods
iv. Loss of normal flora suppresses signals that control enterococci

Front 97

Enterococcus UTI

Back 97

i. Mainly nosocomial
ii. Significant cause of UTI
iii. Dysuria and pyuria
iv. Common in those with indwelling catheter or on broad antibiotics

Front 98

Peritonitis from enterococcus

Back 98

i. Abdominal swelling and tenderness after abdominal trauma or surgery
ii. Patients are typically acutely ill and febrile

Front 99

Endocarditis from enterococcus

Back 99

i. In patients with persistent bacteremia

Front 100

Identification of enterococcus

Back 100

i. High salt, bile, and temp tolerance
ii. Optochin resistant distinguishes it form s. pneumonia
iii. Do not lyse sheep RBCs (white colonies on blood agar)
iv. Usually lytic for human RBCs

Front 101

Anaerobic cocci

Back 101

a. Part of normal flora
b. Colonize oral cavity, GIT, genitourinary tract, and skin

Front 102

Anaerobic cocci in URT

Back 102

i. Sinusitis
ii. Pleuropulmonary infections

Front 103

Anaerobic cocci in GIT

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i. Intra-abdominal infections

Front 104

Anaerobic cocci in GUT

Back 104

i. Endometritis
ii. Pelvic abcesses
iii. Salpingitis

Front 105

Anaerobic cocci on skin

Back 105

i. Cellulitis
ii. Soft tissue infections