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Lecture 19 Flashcards

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1
Q

4 genera of pyogenic cocci

A

Staphylococcus
Streptococcus
Enterococcus
Neisseria
(Ness)

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2
Q

Pyogenic

A

Bacteria that stimulate the formation of pus

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3
Q

Pus caused by

A

Neutrophils

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4
Q

Staphylococcus characteristics

A

Gram positive, spherical cells, arranged in clusters
No spores or flagella
Common inhabitants (microbiota) of swim and mucus membranes

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5
Q

Staphylococcus species

A

Over 40,12 of them colonize humans, 3 of major medical importance

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6
Q

3 staphylococcus species of major medical importance

A

S. aureus
S. epidermidis
S. saprophyticus

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7
Q

S. Aureus

A

Primary pathogen, facultative anaerobe, catalase positive, 10-46°C but 37°C ideal makes it good on famines
* most resistant of non-endospore forming pathogens
Can with stand 7.5 - 10 percent salt, pH 4-10, drying (thick pg layer), resistant to some antibiotics (MRSA VRSA), heat up to 60°C

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8
Q

S. aureus virulence factors (6)

A

Protein A- causes antibodies to bind f(c) region so it doesn’t stimulate an immune response
Coagulase- enzyme that clots blood, restricts blood flow to area preventing neutrophil * used diagnostically to differentiate S. aureus from other staphylococci
Hyaluronidase- digests hyaluronic acid in the basement membrane of tissues to infect deeper since non-motile aka spreading factor
Staphylokinase- digests blood clots
Lipase- digests lipids and oils on skin as nutrition and to more easily colonize skin
Penicillinase- antibiotic resistance enzyme, inactivates beta-lactam ring

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9
Q

S. aureus exotoxins

A

Hemolysins- lyse red blood cells that contain lots of protein and iron to eat
Leukocidins - lyse white blood cells
Enterotoxins- exotoxins that act on GI tract inducing nausea, vomiting, diarrhea
Toxic shock syndrome toxin (tsst)- systemic effects fever, vomiting, rash, shock from major vasodilation BP drops brain doesn’t relieve enough blood

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10
Q

3 types staphylococcal diseases

A

Localized pyogenic, systemic, toxigenic infections

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11
Q

Localized staph aureus infections

A

Invades skin through wounds, follicles, and glands
Causes abcess/boils (inflamed lesion with a core of pus) which either go away on their own or need to be drained

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12
Q

Furuncle

A

Abscess resulting from an infected hair follicle

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13
Q

Carbuncle

A

Deeper access formed by an aggregation of furuncles

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14
Q

Impetigo

A

Localized S. aureus infection, infection of the epidermis characterized by honey-crusted skin lesions
Common in newborns and young children

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15
Q

Systemic staph aureus diseases

A

Usually caused by spreading from local cutaneous infection to other sites via bloodstream

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16
Q

Bacteremia

A

Systemic staph aureus infection, the presence of viable bacteria in the blood

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17
Q

Osteomyelitis

A

Systemic Staph aureus Infection of the bone creates pus inside bone

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18
Q

Endocarditis

A

Infection of inner heart lining and values
Can cause permanent valve damage and mur murs

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19
Q

3 toxigenic staph aureus diseases

A

Food intoxication, scalded skin syndrome, toxic shock syndrome

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20
Q

Food intoxication

A

Toxigenic staph aureus disease caused by hear stable enterotoxins produced by the bacteria, associated with foods rich in carbs like cream, pastries, potato salad, processed meats

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21
Q

Acute vomiting

A

Vomiting that occurs 1-6 hours after ingestion

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22
Q

Scalded skin syndrome

A

Toxigenic staph aureus disease, grows on skin and secretes exfoliative toxin causing upper skin layer separation
Young kids + newborns prone

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23
Q

Toxic shock syndrome

A

Toxigenic staph aureus disease, first identified through tampon use, causes fever, vomiting, rash, and shock
Some women have staph aureus in the vagina that release this

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24
Q

Most important test for distinguishing staph aureus from other staphylococci

A

Catalase test, Also helps differentiate staph and streptococcus

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25
Coagulate test
Added to rabbit serum either clumps or does not Clumping = positive staph aureus Negative= other staphylococcus species or streptococcus
26
CNS
Coagulase negative staph
27
Streptococcus
Gram positive, spherical/ovoid, arranged in bead-like chains Non-spore forming non-motile Common inhabitants of throat and nasopharynx and sometimes skin Facultative anaerobes, catalase negative, fastidious needs enriched media, Small round colonies that are translucent or gray
28
Allows for differentiation of streptococci from staphylococci
Streptococci are catalase negative
29
Lancefield classification system
Rebecca craighill lancefield, based on cell wall carbohydrates displayed by each, 17 different alphabetical groups A to O
30
Group A strep
Strep pyogenes, primary human pathogen, 95% all streptococcal diseases
31
Gas
Group A strep
32
Group B
Streptococcus agalactiae, responsible for neonatal infections, some moms have it in birth canal Can cause neonatal meningitis and sepsis blood infection
33
Group D strep
Enterococcus from large intestine or fecal matter causes several human infections especially nosocomial infections and UTIs Feces contaminates bed pans, catheters, etc
34
Beta hemolytic
GAS, GBS, GCS
35
Alpha hemolysis
Incomplete hemolysis, strep pneumonie and viridans strep
36
Gamma hemolysis
No hemolysis, some GDS
37
Strep pyogenes/group A strep
Strict parasite, inhabits throat/nasopharynx sometimes skin mucus membranes Surface antigens: 1. C-carbohydrates unique technic acids used for Lance field, protects against lysozyme 2. M protein for fimbriae Exoenzymes: 1. Streptokinase 2. Hyaluronidase Exotoxins: 1. hemolysins 2. Erythrogenic toxin- exotoxin causes fever and rash in strep throat infections
38
Determine if impetigo caused by staph or strep
Catalase test or with microscope
39
Erysipelas
Infection in the dermis caused by a deep wound or incision Forms red hot rash via mast and releasing histamine
40
Streptococcal pharyngitis
Localized strep pyogenes Multiplies in tonsils or pharyngeal mucous membranes Causes redness, edema, extreme tenderness, painful swallowing, fever, headache Purulent exudate (pus) over the tonsils
41
Scarlet fever
Systemic strep pyogenes, lysogenic strain releases erythrogenic toxin causing systemic bright red rash over body (scariatina) and strawberry tongue
42
Rheumatic never
Systemic strep pyogenes, if bacteria enters the bloodstream it can attach to and damage heart valves leading to heart disease and murmurs
43
Necrotizing fascitis
Group A strep, flesh-eating bacteria, virulent group A toxins and enzymes that destroy tissues Strep pyogenes enters through a break in the skin Tissues destroyed in hours
44
Necrotizing fasciitis progression
Cellulitis with no clear margins+ painful develops, then bullae (large blisters) form after a few hours organism releasing toxins, then gangrene which is permanent tissue death, massive tissue necrosis, systemic symptoms, multi-system organ failure
45
Enterococcus/group D strep
Enterococcus faecalis and faecium found in large numbers in the large intestine, normal microbiota Cause opportunistic infections of the urinary tract, wounds and bacteremia Endogenous from own intestines
46
Risk for enterococcus/strep D
Patients who have been hospitalized for prolonged periods or treated with broad spectrum antibiotics that enterococci are resistant to like VRE
47
Viridans streptococci
Alpha hemolysis, most numerous resident of oral cavity, nasopharynx, GI tract, and skin Dental or surgical procedures can facilitate entrance
48
Strep mutans
Dental caries and tooth abscess, opportunistic
49
Subacute endocarditis
Blood borne bacteria settle and grow in inner heart lining and values
50
Viridans group can cause
Bacteremia, meningitis, and abdominal infection
51
Streptococcus pneumoniae/ pneumococcus
Significant human pathogen, 60-70% all bacterial pneumonias, a main cause bacterial meningitis, lancet shaped cells in diplococcus or short chains Humans principal reservoir carrying in nasopharynx
52
Streptococcus pneumoniae virulence factors
Pronounced capsule present in all pathogenic strains of strep pneumoniae, 90 different capsular types found with Quellung test, subunit vaccines target capsular strains
53
Quellung test
Capsular swelling test using antiserum specific for a capsule type, can be used to figure out strain patient has in lungs
54
Strep pneumoniae vaccine for infants
Prevnar 13 for infants, 13 capsules
55
Strep pneumoniae vaccine for adults
23 and older
56
What allows strep pneumoniae to enter lower respiratory tract
Presence of compromising factors that impair mucociliary motion, cough reflex, etc Once in the lungs the bacteria can evade non-specific host defenses like phagocytosis due to its large capsule
57
#1 cause strep pneumoniae
Ottis media, a middle ear infection that is very common in US children, pneumococcus gains access via the Eustachian tube (connects ear to throat)
58
Most susceptible to strep pneumoniae
Children under 2 because of shorter rustachian tube
59
Neisseria
Aerobic, gram negative diplococci with flattened adjacent sides, non-spore forming and no flagella, most opportunistic colonize mucous membranes, pathogenic ones are strict parasites
60
Pathogenic neisseria
Strict parasite, capsules and fimbriae as main virulence factors, very fastidious
61
Neisseria may be cultured on
Chocolate agar containing heated blood and/or hemoglobin for enrichmen, heating breaks open blood cells for them since they're non hemolyti
62
Selective media for neisseria
Thayer-martin agar containing 3 antibiotics that inhibit other microbes
63
2 primary pathogenic neisseria
Neisseria ghonorrhoeae Neisseria meningitidis
64
Neisseria gonorrhoeae
Aka gonococcus, eriological agent gonorrhea, one of top five STDs worldwide, strictly human infection, no more than 1-2 hours on formites, asymptomatic in 10% males and 50% females
65
Neisseria gonorrhoeae virulence factors
Fimbriae IgA protease- destroys the IgA secretary antibody on host mucosal surfaces Capsule blocks phagocytosis Endotoxin Los highly toxic
66
Gonorrhea in males
Infection mostly restricted to urethra causing urethritis (inflamed urethra) and painful urination Prolific pus production Could resolve on own, occasionally spread to prostate and epididymis leading to infertility
67
Gonorrhea in females
Primary site of infection is cervix but can be isolated from urethra, vagina, and rectum Vaginal discharge, painful urination, vaginitis, urethritis, and salpingitis (inflammation of the fallopian tubes) PID (pelvic inflammatory disease)
68
Gonorrhea in females can lead to
Infertility or ectopic pregnancies later in life due to scarring of fallopian tubes
69
Gonorrhea in new barns
Infected as pass through birth canal, eye inflammation, purulent conjunctivitis which can lead to blindness, prevented by prophylaxis afte birth using silver nitrate or other antibiotic drops Pregnant women should he screened
70
New cases gonorrhea each year
500,000 every year in US
71
Does prior infection provide long-term immunity for gonorrhea
No, lots of strains
72
Neisseria meningitidis
Aka meningococcus causes epidemic cerebrospinal meningitis, highest incidence kids under 5, 2nd most common cause in adults (after strep pneumoniae), human reservoir in nasopharyny, spreads within families and communities
73
Neisseria meningitidis virulence factors
Capsule, fimbriae, IgA protease, endotoxin LOS
74
Neisseria meningitidis transmission
Aerosolized respiratory droplets especially in crowded situations
75
Neisseria meningitidis entrance and progression of meningitis
Enters respiratory tract, crosses mucosal barrier, enters blood stream, bacteremia allows it to travel to brain and cross BBB, establish infection in meninges Headache, fever, nausea, vomiting, stiff neck Endotoxin release can cause hemorrhage and shock
76
Meningitis mortality
100% untreated, drops to 10% with treatment
77
Meningitis diagnosis
CSF specimen cultured or gram stand
78
Meningitis vaccine?
Meningococcal vaccine, subunit vaccine using capsular polysaccharides, recommended for all ages especially during outbreaks dermis, military base, etc Antibiotic prophylaxis for those with significant exposure to the sick

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